ValueTracking.cpp revision 14b2a59301e9e4065c7b9b07a0c68462b6037a4f
1173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner//===- ValueTracking.cpp - Walk computations to compute properties --------===// 2173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner// 3173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner// The LLVM Compiler Infrastructure 4173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner// 5173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner// This file is distributed under the University of Illinois Open Source 6173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner// License. See LICENSE.TXT for details. 7173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner// 8173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner//===----------------------------------------------------------------------===// 9173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner// 10173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner// This file contains routines that help analyze properties that chains of 11173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner// computations have. 12173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner// 13173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner//===----------------------------------------------------------------------===// 14173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 15173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner#include "llvm/Analysis/ValueTracking.h" 16243712720ad1da144d4376bdd854d81260c1beaaDan Gohman#include "llvm/Analysis/InstructionSimplify.h" 17173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner#include "llvm/Constants.h" 18173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner#include "llvm/Instructions.h" 190ff39b3feb10477c224138156941234f5fa46f58Evan Cheng#include "llvm/GlobalVariable.h" 20307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman#include "llvm/GlobalAlias.h" 21173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner#include "llvm/IntrinsicInst.h" 2276f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson#include "llvm/LLVMContext.h" 23ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman#include "llvm/Operator.h" 240582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling#include "llvm/Target/TargetData.h" 25173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner#include "llvm/Support/GetElementPtrTypeIterator.h" 26173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner#include "llvm/Support/MathExtras.h" 27d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands#include "llvm/Support/PatternMatch.h" 2825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher#include "llvm/ADT/SmallPtrSet.h" 2932a9e7a2654c4aab2e617fbe53140492b3d38066Chris Lattner#include <cstring> 30173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattnerusing namespace llvm; 31d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sandsusing namespace llvm::PatternMatch; 32d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 33d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sandsconst unsigned MaxDepth = 6; 34d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 35d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// getBitWidth - Returns the bitwidth of the given scalar or pointer type (if 36d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// unknown returns 0). For vector types, returns the element type's bitwidth. 37d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sandsstatic unsigned getBitWidth(const Type *Ty, const TargetData *TD) { 38d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (unsigned BitWidth = Ty->getScalarSizeInBits()) 39d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return BitWidth; 40d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands assert(isa<PointerType>(Ty) && "Expected a pointer type!"); 41d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return TD ? TD->getPointerSizeInBits() : 0; 42d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands} 43173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 44173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// ComputeMaskedBits - Determine which of the bits specified in Mask are 45173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// known to be either zero or one and return them in the KnownZero/KnownOne 46173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// bit sets. This code only analyzes bits in Mask, in order to short-circuit 47173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// processing. 48173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// NOTE: we cannot consider 'undef' to be "IsZero" here. The problem is that 49173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// we cannot optimize based on the assumption that it is zero without changing 50173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// it to be an explicit zero. If we don't change it to zero, other code could 51173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// optimized based on the contradictory assumption that it is non-zero. 52173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// Because instcombine aggressively folds operations with undef args anyway, 53173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// this won't lose us code quality. 54cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// 55cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// This function is defined on values with integer type, values with pointer 56cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// type (but only if TD is non-null), and vectors of integers. In the case 57cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// where V is a vector, the mask, known zero, and known one values are the 58cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// same width as the vector element, and the bit is set only if it is true 59cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// for all of the elements in the vector. 60173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattnervoid llvm::ComputeMaskedBits(Value *V, const APInt &Mask, 61173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt &KnownZero, APInt &KnownOne, 62846a2f2703f6bb894098274964faf5dce0b68c4dDan Gohman const TargetData *TD, unsigned Depth) { 63173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert(V && "No Value?"); 649004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman assert(Depth <= MaxDepth && "Limit Search Depth"); 6579abedb83a4dd7d3583c7ca6df8283079acc3ba5Chris Lattner unsigned BitWidth = Mask.getBitWidth(); 661df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands assert((V->getType()->isIntOrIntVectorTy() || V->getType()->isPointerTy()) 67b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands && "Not integer or pointer type!"); 686de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman assert((!TD || 696de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman TD->getTypeSizeInBits(V->getType()->getScalarType()) == BitWidth) && 70b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands (!V->getType()->isIntOrIntVectorTy() || 716de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman V->getType()->getScalarSizeInBits() == BitWidth) && 72173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero.getBitWidth() == BitWidth && 73173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne.getBitWidth() == BitWidth && 74173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner "V, Mask, KnownOne and KnownZero should have same BitWidth"); 75173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 76173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 77173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // We know all of the bits for a constant! 78173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne = CI->getValue() & Mask; 79173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = ~KnownOne & Mask; 80173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 81173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 826de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman // Null and aggregate-zero are all-zeros. 836de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman if (isa<ConstantPointerNull>(V) || 846de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman isa<ConstantAggregateZero>(V)) { 857a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownOne.clearAllBits(); 86173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = Mask; 87173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 88173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 896de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman // Handle a constant vector by taking the intersection of the known bits of 906de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman // each element. 916de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman if (ConstantVector *CV = dyn_cast<ConstantVector>(V)) { 927a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownZero.setAllBits(); KnownOne.setAllBits(); 936de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) { 946de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman APInt KnownZero2(BitWidth, 0), KnownOne2(BitWidth, 0); 956de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman ComputeMaskedBits(CV->getOperand(i), Mask, KnownZero2, KnownOne2, 966de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman TD, Depth); 976de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman KnownZero &= KnownZero2; 986de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman KnownOne &= KnownOne2; 996de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman } 1006de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman return; 1016de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman } 102173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // The address of an aligned GlobalValue has trailing zeros. 103173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { 104173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned Align = GV->getAlignment(); 105004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman if (Align == 0 && TD && GV->getType()->getElementType()->isSized()) { 106004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman const Type *ObjectType = GV->getType()->getElementType(); 107004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman // If the object is defined in the current Module, we'll be giving 108004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman // it the preferred alignment. Otherwise, we have to assume that it 109004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman // may only have the minimum ABI alignment. 110004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman if (!GV->isDeclaration() && !GV->mayBeOverridden()) 111004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman Align = TD->getPrefTypeAlignment(ObjectType); 112004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman else 113004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman Align = TD->getABITypeAlignment(ObjectType); 114004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman } 115173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Align > 0) 116173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = Mask & APInt::getLowBitsSet(BitWidth, 117173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner CountTrailingZeros_32(Align)); 118173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner else 1197a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownZero.clearAllBits(); 1207a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownOne.clearAllBits(); 121173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 122173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 123307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman // A weak GlobalAlias is totally unknown. A non-weak GlobalAlias has 124307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman // the bits of its aliasee. 125307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { 126307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman if (GA->mayBeOverridden()) { 1277a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownZero.clearAllBits(); KnownOne.clearAllBits(); 128307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman } else { 129307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman ComputeMaskedBits(GA->getAliasee(), Mask, KnownZero, KnownOne, 130307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman TD, Depth+1); 131307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman } 132307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman return; 133307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman } 134173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 1357a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownZero.clearAllBits(); KnownOne.clearAllBits(); // Start out not knowing anything. 136173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 1379004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman if (Depth == MaxDepth || Mask == 0) 138173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; // Limit search depth. 139173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 140ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman Operator *I = dyn_cast<Operator>(V); 141173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!I) return; 142173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 143173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero2(KnownZero), KnownOne2(KnownOne); 144ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman switch (I->getOpcode()) { 145173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner default: break; 146173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::And: { 147173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If either the LHS or the RHS are Zero, the result is zero. 148173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, TD, Depth+1); 149173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2(Mask & ~KnownZero); 150173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD, 151173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 152173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 153173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); 154173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 155173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Output known-1 bits are only known if set in both the LHS & RHS. 156173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne &= KnownOne2; 157173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Output known-0 are known to be clear if zero in either the LHS | RHS. 158173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= KnownZero2; 159173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 160173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 161173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Or: { 162173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, TD, Depth+1); 163173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2(Mask & ~KnownOne); 164173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD, 165173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 166173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 167173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); 168173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 169173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Output known-0 bits are only known if clear in both the LHS & RHS. 170173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero &= KnownZero2; 171173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Output known-1 are known to be set if set in either the LHS | RHS. 172173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne |= KnownOne2; 173173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 174173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 175173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Xor: { 176173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, TD, Depth+1); 177173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, TD, 178173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 179173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 180173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); 181173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 182173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Output known-0 bits are known if clear or set in both the LHS & RHS. 183173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2); 184173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Output known-1 are known to be set if set in only one of the LHS, RHS. 185173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2); 186173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = KnownZeroOut; 187173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 188173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 189173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Mul: { 190173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2 = APInt::getAllOnesValue(BitWidth); 191173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), Mask2, KnownZero, KnownOne, TD,Depth+1); 192173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD, 193173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 194173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 195173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); 196173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 197173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If low bits are zero in either operand, output low known-0 bits. 198173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Also compute a conserative estimate for high known-0 bits. 199173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // More trickiness is possible, but this is sufficient for the 200173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // interesting case of alignment computation. 2017a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownOne.clearAllBits(); 202173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned TrailZ = KnownZero.countTrailingOnes() + 203173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero2.countTrailingOnes(); 204173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned LeadZ = std::max(KnownZero.countLeadingOnes() + 205173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero2.countLeadingOnes(), 206173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner BitWidth) - BitWidth; 207173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 208173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TrailZ = std::min(TrailZ, BitWidth); 209173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LeadZ = std::min(LeadZ, BitWidth); 210173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getLowBitsSet(BitWidth, TrailZ) | 211173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt::getHighBitsSet(BitWidth, LeadZ); 212173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero &= Mask; 213173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 214173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 215173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::UDiv: { 216173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // For the purposes of computing leading zeros we can conservatively 217173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // treat a udiv as a logical right shift by the power of 2 known to 218173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // be less than the denominator. 219173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt AllOnes = APInt::getAllOnesValue(BitWidth); 220173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), 221173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner AllOnes, KnownZero2, KnownOne2, TD, Depth+1); 222173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned LeadZ = KnownZero2.countLeadingOnes(); 223173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 2247a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownOne2.clearAllBits(); 2257a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownZero2.clearAllBits(); 226173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), 227173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner AllOnes, KnownZero2, KnownOne2, TD, Depth+1); 228173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned RHSUnknownLeadingOnes = KnownOne2.countLeadingZeros(); 229173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (RHSUnknownLeadingOnes != BitWidth) 230173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LeadZ = std::min(BitWidth, 231173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LeadZ + BitWidth - RHSUnknownLeadingOnes - 1); 232173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 233173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getHighBitsSet(BitWidth, LeadZ) & Mask; 234173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 235173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 236173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Select: 237173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(2), Mask, KnownZero, KnownOne, TD, Depth+1); 238173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), Mask, KnownZero2, KnownOne2, TD, 239173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 240173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 241173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); 242173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 243173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Only known if known in both the LHS and RHS. 244173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne &= KnownOne2; 245173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero &= KnownZero2; 246173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 247173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::FPTrunc: 248173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::FPExt: 249173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::FPToUI: 250173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::FPToSI: 251173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::SIToFP: 252173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::UIToFP: 253173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; // Can't work with floating point. 254173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::PtrToInt: 255173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::IntToPtr: 256173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // We can't handle these if we don't know the pointer size. 257173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!TD) return; 258173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // FALL THROUGH and handle them the same as zext/trunc. 259173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::ZExt: 260173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Trunc: { 261b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner const Type *SrcTy = I->getOperand(0)->getType(); 262b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner 263b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner unsigned SrcBitWidth; 264173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Note that we handle pointer operands here because of inttoptr/ptrtoint 265173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // which fall through here. 2661df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (SrcTy->isPointerTy()) 267b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner SrcBitWidth = TD->getTypeSizeInBits(SrcTy); 268b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner else 269b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner SrcBitWidth = SrcTy->getScalarSizeInBits(); 270b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner 27140f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad APInt MaskIn = Mask.zextOrTrunc(SrcBitWidth); 27240f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownZero = KnownZero.zextOrTrunc(SrcBitWidth); 27340f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownOne = KnownOne.zextOrTrunc(SrcBitWidth); 274173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, TD, 275173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 27640f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownZero = KnownZero.zextOrTrunc(BitWidth); 27740f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownOne = KnownOne.zextOrTrunc(BitWidth); 278173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Any top bits are known to be zero. 279173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (BitWidth > SrcBitWidth) 280173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth); 281173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 282173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 283173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::BitCast: { 284173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner const Type *SrcTy = I->getOperand(0)->getType(); 2851df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if ((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && 2860dabb0b177089202dae485d085ed15bd41ef29e6Chris Lattner // TODO: For now, not handling conversions like: 2870dabb0b177089202dae485d085ed15bd41ef29e6Chris Lattner // (bitcast i64 %x to <2 x i32>) 2881df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands !I->getType()->isVectorTy()) { 289173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, TD, 290173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 291173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 292173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 293173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 294173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 295173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::SExt: { 296173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Compute the bits in the result that are not present in the input. 297b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits(); 298173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 29940f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad APInt MaskIn = Mask.trunc(SrcBitWidth); 30040f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownZero = KnownZero.trunc(SrcBitWidth); 30140f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownOne = KnownOne.trunc(SrcBitWidth); 302173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, TD, 303173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 304173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 30540f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownZero = KnownZero.zext(BitWidth); 30640f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownOne = KnownOne.zext(BitWidth); 307173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 308173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If the sign bit of the input is known set or clear, then we know the 309173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // top bits of the result. 310173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero[SrcBitWidth-1]) // Input sign bit known zero 311173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth); 312173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner else if (KnownOne[SrcBitWidth-1]) // Input sign bit known set 313173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth); 314173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 315173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 316173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Shl: 317173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0 318173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { 319173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner uint64_t ShiftAmt = SA->getLimitedValue(BitWidth); 320173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2(Mask.lshr(ShiftAmt)); 321173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, TD, 322173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 323173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 324173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero <<= ShiftAmt; 325173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne <<= ShiftAmt; 326173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt); // low bits known 0 327173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 328173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 329173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 330173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::LShr: 331173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0 332173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { 333173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Compute the new bits that are at the top now. 334173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner uint64_t ShiftAmt = SA->getLimitedValue(BitWidth); 335173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 336173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Unsigned shift right. 337173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2(Mask.shl(ShiftAmt)); 338173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero,KnownOne, TD, 339173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 340ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 341173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APIntOps::lshr(KnownZero, ShiftAmt); 342173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne = APIntOps::lshr(KnownOne, ShiftAmt); 343173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // high bits known zero. 344173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= APInt::getHighBitsSet(BitWidth, ShiftAmt); 345173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 346173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 347173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 348173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::AShr: 349173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // (ashr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0 350173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { 351173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Compute the new bits that are at the top now. 35243b40a4620c155c73ac71b48472ea2411d7c35daChris Lattner uint64_t ShiftAmt = SA->getLimitedValue(BitWidth-1); 353173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 354173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Signed shift right. 355173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2(Mask.shl(ShiftAmt)); 356173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, TD, 357173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 358ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 359173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APIntOps::lshr(KnownZero, ShiftAmt); 360173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne = APIntOps::lshr(KnownOne, ShiftAmt); 361173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 362173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt)); 363173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero[BitWidth-ShiftAmt-1]) // New bits are known zero. 364173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= HighBits; 365173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner else if (KnownOne[BitWidth-ShiftAmt-1]) // New bits are known one. 366173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne |= HighBits; 367173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 368173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 369173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 370173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Sub: { 371173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *CLHS = dyn_cast<ConstantInt>(I->getOperand(0))) { 372173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // We know that the top bits of C-X are clear if X contains less bits 373173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // than C (i.e. no wrap-around can happen). For example, 20-X is 374173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // positive if we can prove that X is >= 0 and < 16. 375173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!CLHS->getValue().isNegative()) { 376173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned NLZ = (CLHS->getValue()+1).countLeadingZeros(); 377173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // NLZ can't be BitWidth with no sign bit 378173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt MaskV = APInt::getHighBitsSet(BitWidth, NLZ+1); 379173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), MaskV, KnownZero2, KnownOne2, 380173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TD, Depth+1); 381173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 382173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If all of the MaskV bits are known to be zero, then we know the 383173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // output top bits are zero, because we now know that the output is 384173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // from [0-C]. 385173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if ((KnownZero2 & MaskV) == MaskV) { 386173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned NLZ2 = CLHS->getValue().countLeadingZeros(); 387173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Top bits known zero. 388173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getHighBitsSet(BitWidth, NLZ2) & Mask; 389173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 390173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 391173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 392173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 393173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // fall through 394173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Add: { 395ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky // If one of the operands has trailing zeros, then the bits that the 3963925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // other operand has in those bit positions will be preserved in the 3973925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // result. For an add, this works with either operand. For a subtract, 3983925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // this only works if the known zeros are in the right operand. 3993925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0); 4003925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman APInt Mask2 = APInt::getLowBitsSet(BitWidth, 4013925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman BitWidth - Mask.countLeadingZeros()); 4023925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman ComputeMaskedBits(I->getOperand(0), Mask2, LHSKnownZero, LHSKnownOne, TD, 403173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 4043925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman assert((LHSKnownZero & LHSKnownOne) == 0 && 4053925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman "Bits known to be one AND zero?"); 4063925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman unsigned LHSKnownZeroOut = LHSKnownZero.countTrailingOnes(); 407173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 408173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), Mask2, KnownZero2, KnownOne2, TD, 409173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 410173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); 4113925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman unsigned RHSKnownZeroOut = KnownZero2.countTrailingOnes(); 412173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 4133925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // Determine which operand has more trailing zeros, and use that 4143925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // many bits from the other operand. 4153925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman if (LHSKnownZeroOut > RHSKnownZeroOut) { 416ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman if (I->getOpcode() == Instruction::Add) { 4173925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman APInt Mask = APInt::getLowBitsSet(BitWidth, LHSKnownZeroOut); 4183925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman KnownZero |= KnownZero2 & Mask; 4193925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman KnownOne |= KnownOne2 & Mask; 4203925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman } else { 4213925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // If the known zeros are in the left operand for a subtract, 4223925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // fall back to the minimum known zeros in both operands. 4233925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman KnownZero |= APInt::getLowBitsSet(BitWidth, 4243925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman std::min(LHSKnownZeroOut, 4253925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman RHSKnownZeroOut)); 4263925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman } 4273925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman } else if (RHSKnownZeroOut >= LHSKnownZeroOut) { 4283925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman APInt Mask = APInt::getLowBitsSet(BitWidth, RHSKnownZeroOut); 4293925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman KnownZero |= LHSKnownZero & Mask; 4303925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman KnownOne |= LHSKnownOne & Mask; 4313925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman } 432b69050a94c1c9266ab048a79c8375e5b14d87c72Nick Lewycky 433b69050a94c1c9266ab048a79c8375e5b14d87c72Nick Lewycky // Are we still trying to solve for the sign bit? 43414b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer if (Mask.isNegative() && !KnownZero.isNegative() && !KnownOne.isNegative()){ 435b69050a94c1c9266ab048a79c8375e5b14d87c72Nick Lewycky OverflowingBinaryOperator *OBO = cast<OverflowingBinaryOperator>(I); 436b69050a94c1c9266ab048a79c8375e5b14d87c72Nick Lewycky if (OBO->hasNoSignedWrap()) { 43714b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer if (I->getOpcode() == Instruction::Add) { 43814b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer // Adding two positive numbers can't wrap into negative 43914b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer if (LHSKnownZero.isNegative() && KnownZero2.isNegative()) 44014b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer KnownZero |= APInt::getSignBit(BitWidth); 44114b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer // and adding two negative numbers can't wrap into positive. 44214b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer else if (LHSKnownOne.isNegative() && KnownOne2.isNegative()) 44314b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer KnownOne |= APInt::getSignBit(BitWidth); 44414b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer } else { 44514b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer // Subtracting a negative number from a positive one can't wrap 44614b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer if (LHSKnownZero.isNegative() && KnownOne2.isNegative()) 44714b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer KnownZero |= APInt::getSignBit(BitWidth); 44814b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer // neither can subtracting a positive number from a negative one. 44914b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer else if (LHSKnownOne.isNegative() && KnownZero2.isNegative()) 45014b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer KnownOne |= APInt::getSignBit(BitWidth); 45114b2a59301e9e4065c7b9b07a0c68462b6037a4fBenjamin Kramer } 452b69050a94c1c9266ab048a79c8375e5b14d87c72Nick Lewycky } 453b69050a94c1c9266ab048a79c8375e5b14d87c72Nick Lewycky } 454b69050a94c1c9266ab048a79c8375e5b14d87c72Nick Lewycky 455173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 456173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 457173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::SRem: 458173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { 459cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands APInt RA = Rem->getValue().abs(); 460cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands if (RA.isPowerOf2()) { 461cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands APInt LowBits = RA - 1; 462173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2 = LowBits | APInt::getSignBit(BitWidth); 463173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD, 464173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 465173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 466cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // The low bits of the first operand are unchanged by the srem. 467cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownZero = KnownZero2 & LowBits; 468cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownOne = KnownOne2 & LowBits; 469cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands 470cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // If the first operand is non-negative or has all low bits zero, then 471cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // the upper bits are all zero. 472173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero2[BitWidth-1] || ((KnownZero2 & LowBits) == LowBits)) 473cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownZero |= ~LowBits; 474173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 475cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // If the first operand is negative and not all low bits are zero, then 476cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // the upper bits are all one. 477cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands if (KnownOne2[BitWidth-1] && ((KnownOne2 & LowBits) != 0)) 478cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownOne |= ~LowBits; 479cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands 480cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownZero &= Mask; 481cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownOne &= Mask; 482173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 483ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 484173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 485173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 486c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky 487c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky // The sign bit is the LHS's sign bit, except when the result of the 488c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky // remainder is zero. 489c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky if (Mask.isNegative() && KnownZero.isNonNegative()) { 490c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky APInt Mask2 = APInt::getSignBit(BitWidth); 491c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0); 492c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky ComputeMaskedBits(I->getOperand(0), Mask2, LHSKnownZero, LHSKnownOne, TD, 493c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky Depth+1); 494c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky // If it's known zero, our sign bit is also zero. 495c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky if (LHSKnownZero.isNegative()) 496c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky KnownZero |= LHSKnownZero; 497c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky } 498c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky 499173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 500173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::URem: { 501173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { 502173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt RA = Rem->getValue(); 503173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (RA.isPowerOf2()) { 504173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt LowBits = (RA - 1); 505173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2 = LowBits & Mask; 506173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= ~LowBits & Mask; 507173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, TD, 508173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 509ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 510173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 511173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 512173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 513173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 514173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Since the result is less than or equal to either operand, any leading 515173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // zero bits in either operand must also exist in the result. 516173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt AllOnes = APInt::getAllOnesValue(BitWidth); 517173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), AllOnes, KnownZero, KnownOne, 518173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TD, Depth+1); 519173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), AllOnes, KnownZero2, KnownOne2, 520173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TD, Depth+1); 521173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 52279abedb83a4dd7d3583c7ca6df8283079acc3ba5Chris Lattner unsigned Leaders = std::max(KnownZero.countLeadingOnes(), 523173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero2.countLeadingOnes()); 5247a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownOne.clearAllBits(); 525173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getHighBitsSet(BitWidth, Leaders) & Mask; 526173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 527173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 528173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 529a276c603b82a11b0bf0b59f0517a69e4b63adeabVictor Hernandez case Instruction::Alloca: { 5307b929dad59785f62a66f7c58615082f98441e95eVictor Hernandez AllocaInst *AI = cast<AllocaInst>(V); 531173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned Align = AI->getAlignment(); 532a276c603b82a11b0bf0b59f0517a69e4b63adeabVictor Hernandez if (Align == 0 && TD) 533a276c603b82a11b0bf0b59f0517a69e4b63adeabVictor Hernandez Align = TD->getABITypeAlignment(AI->getType()->getElementType()); 534173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 535173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Align > 0) 536173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = Mask & APInt::getLowBitsSet(BitWidth, 537173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner CountTrailingZeros_32(Align)); 538173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 539173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 540173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::GetElementPtr: { 541173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Analyze all of the subscripts of this getelementptr instruction 542173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // to determine if we can prove known low zero bits. 543173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt LocalMask = APInt::getAllOnesValue(BitWidth); 544173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt LocalKnownZero(BitWidth, 0), LocalKnownOne(BitWidth, 0); 545173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), LocalMask, 546173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LocalKnownZero, LocalKnownOne, TD, Depth+1); 547173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned TrailZ = LocalKnownZero.countTrailingOnes(); 548173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 549173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner gep_type_iterator GTI = gep_type_begin(I); 550173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i, ++GTI) { 551173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *Index = I->getOperand(i); 552173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (const StructType *STy = dyn_cast<StructType>(*GTI)) { 553173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Handle struct member offset arithmetic. 554173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!TD) return; 555173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner const StructLayout *SL = TD->getStructLayout(STy); 556173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned Idx = cast<ConstantInt>(Index)->getZExtValue(); 557173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner uint64_t Offset = SL->getElementOffset(Idx); 558173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TrailZ = std::min(TrailZ, 559173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner CountTrailingZeros_64(Offset)); 560173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } else { 561173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Handle array index arithmetic. 562173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner const Type *IndexedTy = GTI.getIndexedType(); 563173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!IndexedTy->isSized()) return; 5646de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman unsigned GEPOpiBits = Index->getType()->getScalarSizeInBits(); 565777d2306b36816a53bc1ae1244c0dc7d998ae691Duncan Sands uint64_t TypeSize = TD ? TD->getTypeAllocSize(IndexedTy) : 1; 566173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LocalMask = APInt::getAllOnesValue(GEPOpiBits); 567173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LocalKnownZero = LocalKnownOne = APInt(GEPOpiBits, 0); 568173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(Index, LocalMask, 569173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LocalKnownZero, LocalKnownOne, TD, Depth+1); 570173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TrailZ = std::min(TrailZ, 57179abedb83a4dd7d3583c7ca6df8283079acc3ba5Chris Lattner unsigned(CountTrailingZeros_64(TypeSize) + 57279abedb83a4dd7d3583c7ca6df8283079acc3ba5Chris Lattner LocalKnownZero.countTrailingOnes())); 573173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 574173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 575173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 576173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getLowBitsSet(BitWidth, TrailZ) & Mask; 577173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 578173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 579173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::PHI: { 580173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner PHINode *P = cast<PHINode>(I); 581173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Handle the case of a simple two-predecessor recurrence PHI. 582173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // There's a lot more that could theoretically be done here, but 583173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // this is sufficient to catch some interesting cases. 584173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (P->getNumIncomingValues() == 2) { 585173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner for (unsigned i = 0; i != 2; ++i) { 586173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *L = P->getIncomingValue(i); 587173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *R = P->getIncomingValue(!i); 588ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman Operator *LU = dyn_cast<Operator>(L); 589173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!LU) 590173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner continue; 591ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman unsigned Opcode = LU->getOpcode(); 592173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Check for operations that have the property that if 593173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // both their operands have low zero bits, the result 594173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // will have low zero bits. 595173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Opcode == Instruction::Add || 596173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Opcode == Instruction::Sub || 597173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Opcode == Instruction::And || 598173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Opcode == Instruction::Or || 599173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Opcode == Instruction::Mul) { 600173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *LL = LU->getOperand(0); 601173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *LR = LU->getOperand(1); 602173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Find a recurrence. 603173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (LL == I) 604173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner L = LR; 605173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner else if (LR == I) 606173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner L = LL; 607173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner else 608173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 609173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Ok, we have a PHI of the form L op= R. Check for low 610173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // zero bits. 611173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2 = APInt::getAllOnesValue(BitWidth); 612173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(R, Mask2, KnownZero2, KnownOne2, TD, Depth+1); 613173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask2 = APInt::getLowBitsSet(BitWidth, 614173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero2.countTrailingOnes()); 615c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene 616c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene // We need to take the minimum number of known bits 617c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene APInt KnownZero3(KnownZero), KnownOne3(KnownOne); 618c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene ComputeMaskedBits(L, Mask2, KnownZero3, KnownOne3, TD, Depth+1); 619c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene 620173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = Mask & 621173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt::getLowBitsSet(BitWidth, 622c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene std::min(KnownZero2.countTrailingOnes(), 623c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene KnownZero3.countTrailingOnes())); 624173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 625173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 626173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 627173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 6289004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman 6293b739d278c87f8ac22b5dc368b319fa278347b2fNick Lewycky // Unreachable blocks may have zero-operand PHI nodes. 6303b739d278c87f8ac22b5dc368b319fa278347b2fNick Lewycky if (P->getNumIncomingValues() == 0) 6313b739d278c87f8ac22b5dc368b319fa278347b2fNick Lewycky return; 6323b739d278c87f8ac22b5dc368b319fa278347b2fNick Lewycky 6339004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // Otherwise take the unions of the known bit sets of the operands, 6349004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // taking conservative care to avoid excessive recursion. 6359004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman if (Depth < MaxDepth - 1 && !KnownZero && !KnownOne) { 636606199fb85d1c8407615e575b5e8bb5c71be27bdDuncan Sands // Skip if every incoming value references to ourself. 637606199fb85d1c8407615e575b5e8bb5c71be27bdDuncan Sands if (P->hasConstantValue() == P) 638606199fb85d1c8407615e575b5e8bb5c71be27bdDuncan Sands break; 639606199fb85d1c8407615e575b5e8bb5c71be27bdDuncan Sands 6409004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownZero = APInt::getAllOnesValue(BitWidth); 6419004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownOne = APInt::getAllOnesValue(BitWidth); 6429004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman for (unsigned i = 0, e = P->getNumIncomingValues(); i != e; ++i) { 6439004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // Skip direct self references. 6449004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman if (P->getIncomingValue(i) == P) continue; 6459004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman 6469004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownZero2 = APInt(BitWidth, 0); 6479004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownOne2 = APInt(BitWidth, 0); 6489004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // Recurse, but cap the recursion to one level, because we don't 6499004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // want to waste time spinning around in loops. 6509004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman ComputeMaskedBits(P->getIncomingValue(i), KnownZero | KnownOne, 6519004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownZero2, KnownOne2, TD, MaxDepth-1); 6529004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownZero &= KnownZero2; 6539004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownOne &= KnownOne2; 6549004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // If all bits have been ruled out, there's no need to check 6559004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // more operands. 6569004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman if (!KnownZero && !KnownOne) 6579004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman break; 6589004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman } 6599004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman } 660173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 661173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 662173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Call: 663173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) { 664173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner switch (II->getIntrinsicID()) { 665173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner default: break; 666173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Intrinsic::ctpop: 667173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Intrinsic::ctlz: 668173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Intrinsic::cttz: { 669173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned LowBits = Log2_32(BitWidth)+1; 670173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getHighBitsSet(BitWidth, BitWidth - LowBits); 671173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 672173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 673173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 674173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 675173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 676173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 677173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner} 678173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 679d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// ComputeSignBit - Determine whether the sign bit is known to be zero or 680d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// one. Convenience wrapper around ComputeMaskedBits. 681d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sandsvoid llvm::ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne, 682d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands const TargetData *TD, unsigned Depth) { 683d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands unsigned BitWidth = getBitWidth(V->getType(), TD); 684d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (!BitWidth) { 685d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands KnownZero = false; 686d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands KnownOne = false; 687d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return; 688d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 689d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt ZeroBits(BitWidth, 0); 690d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt OneBits(BitWidth, 0); 691d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeMaskedBits(V, APInt::getSignBit(BitWidth), ZeroBits, OneBits, TD, 692d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands Depth); 693d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands KnownOne = OneBits[BitWidth - 1]; 694d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands KnownZero = ZeroBits[BitWidth - 1]; 695d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands} 696d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 697d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// isPowerOfTwo - Return true if the given value is known to have exactly one 698d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// bit set when defined. For vectors return true if every element is known to 699d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// be a power of two when defined. Supports values with integer or pointer 700d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// types and vectors of integers. 701d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sandsbool llvm::isPowerOfTwo(Value *V, const TargetData *TD, unsigned Depth) { 702d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) 703464a4f349c95a25d06d709e79d7df21fbbb155e2Duncan Sands return CI->getValue().isPowerOf2(); 704d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // TODO: Handle vector constants. 705d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 706d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // 1 << X is clearly a power of two if the one is not shifted off the end. If 707d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // it is shifted off the end then the result is undefined. 708d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (match(V, m_Shl(m_One(), m_Value()))) 709d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 710d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 711d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // (signbit) >>l X is clearly a power of two if the one is not shifted off the 712d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // bottom. If it is shifted off the bottom then the result is undefined. 71393c780288df9631d11f996b010b2212a8b44d4d3Duncan Sands if (match(V, m_LShr(m_SignBit(), m_Value()))) 714d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 715d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 716d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // The remaining tests are all recursive, so bail out if we hit the limit. 717d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (Depth++ == MaxDepth) 718d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return false; 719d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 720d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (ZExtInst *ZI = dyn_cast<ZExtInst>(V)) 721d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return isPowerOfTwo(ZI->getOperand(0), TD, Depth); 722d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 723d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (SelectInst *SI = dyn_cast<SelectInst>(V)) 724d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return isPowerOfTwo(SI->getTrueValue(), TD, Depth) && 725d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands isPowerOfTwo(SI->getFalseValue(), TD, Depth); 726d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 7273dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky // An exact divide or right shift can only shift off zero bits, so the result 728da834093b73ff67ede909f2ac616e0703ac6ce8eNick Lewycky // is a power of two only if the first operand is a power of two. 7293dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky if (match(V, m_Shr(m_Value(), m_Value())) || 7303dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky match(V, m_IDiv(m_Value(), m_Value()))) { 7313dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky BinaryOperator *BO = cast<BinaryOperator>(V); 7323dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky if (BO->isExact()) 7333dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky return isPowerOfTwo(BO->getOperand(0), TD, Depth); 7343dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky } 7353dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky 736d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return false; 737d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands} 738d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 739d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// isKnownNonZero - Return true if the given value is known to be non-zero 740d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// when defined. For vectors return true if every element is known to be 741d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// non-zero when defined. Supports values with integer or pointer type and 742d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// vectors of integers. 743d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sandsbool llvm::isKnownNonZero(Value *V, const TargetData *TD, unsigned Depth) { 744d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (Constant *C = dyn_cast<Constant>(V)) { 745d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (C->isNullValue()) 746d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return false; 747d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (isa<ConstantInt>(C)) 748d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // Must be non-zero due to null test above. 749d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 750d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // TODO: Handle vectors 751d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return false; 752d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 753d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 754d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // The remaining tests are all recursive, so bail out if we hit the limit. 755d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (Depth++ == MaxDepth) 756d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return false; 757d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 758d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands unsigned BitWidth = getBitWidth(V->getType(), TD); 759d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 760d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // X | Y != 0 if X != 0 or Y != 0. 761d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands Value *X = 0, *Y = 0; 762d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (match(V, m_Or(m_Value(X), m_Value(Y)))) 763d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return isKnownNonZero(X, TD, Depth) || isKnownNonZero(Y, TD, Depth); 764d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 765d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // ext X != 0 if X != 0. 766d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (isa<SExtInst>(V) || isa<ZExtInst>(V)) 767d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return isKnownNonZero(cast<Instruction>(V)->getOperand(0), TD, Depth); 768d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 7699136782d273cd45b6f19a7d0cc0d146d0791bac9Duncan Sands // shl X, Y != 0 if X is odd. Note that the value of the shift is undefined 770d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // if the lowest bit is shifted off the end. 771d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (BitWidth && match(V, m_Shl(m_Value(X), m_Value(Y)))) { 7723dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky // shl nuw can't remove any non-zero bits. 7733dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky BinaryOperator *BO = cast<BinaryOperator>(V); 7743dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky if (BO->hasNoUnsignedWrap()) 7753dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky return isKnownNonZero(X, TD, Depth); 7763dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky 777d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt KnownZero(BitWidth, 0); 778d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt KnownOne(BitWidth, 0); 7799136782d273cd45b6f19a7d0cc0d146d0791bac9Duncan Sands ComputeMaskedBits(X, APInt(BitWidth, 1), KnownZero, KnownOne, TD, Depth); 780d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (KnownOne[0]) 781d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 782d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 7839136782d273cd45b6f19a7d0cc0d146d0791bac9Duncan Sands // shr X, Y != 0 if X is negative. Note that the value of the shift is not 784d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // defined if the sign bit is shifted off the end. 785d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands else if (match(V, m_Shr(m_Value(X), m_Value(Y)))) { 7863dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky // shr exact can only shift out zero bits. 7873dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky BinaryOperator *BO = cast<BinaryOperator>(V); 7883dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky if (BO->isExact()) 7893dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky return isKnownNonZero(X, TD, Depth); 7903dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky 791d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands bool XKnownNonNegative, XKnownNegative; 792d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeSignBit(X, XKnownNonNegative, XKnownNegative, TD, Depth); 793d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (XKnownNegative) 794d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 795d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 7963dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky // div exact can only produce a zero if the dividend is zero. 7973dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky else if (match(V, m_IDiv(m_Value(X), m_Value()))) { 7983dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky BinaryOperator *BO = cast<BinaryOperator>(V); 7993dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky if (BO->isExact()) 8003dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky return isKnownNonZero(X, TD, Depth); 8013dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky } 802d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // X + Y. 803d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands else if (match(V, m_Add(m_Value(X), m_Value(Y)))) { 804d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands bool XKnownNonNegative, XKnownNegative; 805d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands bool YKnownNonNegative, YKnownNegative; 806d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeSignBit(X, XKnownNonNegative, XKnownNegative, TD, Depth); 807d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeSignBit(Y, YKnownNonNegative, YKnownNegative, TD, Depth); 808d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 809d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // If X and Y are both non-negative (as signed values) then their sum is not 810227fba11ca168225d913d1cea94a05b883092e76Duncan Sands // zero unless both X and Y are zero. 811d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (XKnownNonNegative && YKnownNonNegative) 812227fba11ca168225d913d1cea94a05b883092e76Duncan Sands if (isKnownNonZero(X, TD, Depth) || isKnownNonZero(Y, TD, Depth)) 813227fba11ca168225d913d1cea94a05b883092e76Duncan Sands return true; 814d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 815d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // If X and Y are both negative (as signed values) then their sum is not 816d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // zero unless both X and Y equal INT_MIN. 817d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (BitWidth && XKnownNegative && YKnownNegative) { 818d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt KnownZero(BitWidth, 0); 819d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt KnownOne(BitWidth, 0); 820d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt Mask = APInt::getSignedMaxValue(BitWidth); 821d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // The sign bit of X is set. If some other bit is set then X is not equal 822d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // to INT_MIN. 823d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeMaskedBits(X, Mask, KnownZero, KnownOne, TD, Depth); 824d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if ((KnownOne & Mask) != 0) 825d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 826d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // The sign bit of Y is set. If some other bit is set then Y is not equal 827d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // to INT_MIN. 828d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeMaskedBits(Y, Mask, KnownZero, KnownOne, TD, Depth); 829d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if ((KnownOne & Mask) != 0) 830d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 831d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 832d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 833d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // The sum of a non-negative number and a power of two is not zero. 834d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (XKnownNonNegative && isPowerOfTwo(Y, TD, Depth)) 835d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 836d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (YKnownNonNegative && isPowerOfTwo(X, TD, Depth)) 837d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 838d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 839d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // (C ? X : Y) != 0 if X != 0 and Y != 0. 840d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands else if (SelectInst *SI = dyn_cast<SelectInst>(V)) { 841d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (isKnownNonZero(SI->getTrueValue(), TD, Depth) && 842d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands isKnownNonZero(SI->getFalseValue(), TD, Depth)) 843d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 844d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 845d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 846d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (!BitWidth) return false; 847d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt KnownZero(BitWidth, 0); 848d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt KnownOne(BitWidth, 0); 849d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeMaskedBits(V, APInt::getAllOnesValue(BitWidth), KnownZero, KnownOne, 850d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands TD, Depth); 851d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return KnownOne != 0; 852d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands} 853d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 854173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use 855173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// this predicate to simplify operations downstream. Mask is known to be zero 856173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// for bits that V cannot have. 857cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// 858cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// This function is defined on values with integer type, values with pointer 859cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// type (but only if TD is non-null), and vectors of integers. In the case 860cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// where V is a vector, the mask, known zero, and known one values are the 861cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// same width as the vector element, and the bit is set only if it is true 862cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// for all of the elements in the vector. 863173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattnerbool llvm::MaskedValueIsZero(Value *V, const APInt &Mask, 864846a2f2703f6bb894098274964faf5dce0b68c4dDan Gohman const TargetData *TD, unsigned Depth) { 865173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero(Mask.getBitWidth(), 0), KnownOne(Mask.getBitWidth(), 0); 866173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth); 867173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 868173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return (KnownZero & Mask) == Mask; 869173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner} 870173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 871173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 872173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 873173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// ComputeNumSignBits - Return the number of times the sign bit of the 874173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// register is replicated into the other bits. We know that at least 1 bit 875173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// is always equal to the sign bit (itself), but other cases can give us 876173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// information. For example, immediately after an "ashr X, 2", we know that 877173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// the top 3 bits are all equal to each other, so we return 3. 878173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// 879173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// 'Op' must have a scalar integer type. 880173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// 881846a2f2703f6bb894098274964faf5dce0b68c4dDan Gohmanunsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD, 882846a2f2703f6bb894098274964faf5dce0b68c4dDan Gohman unsigned Depth) { 883b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands assert((TD || V->getType()->isIntOrIntVectorTy()) && 884bd5ce52740700bb482fb2b5a03bce781acbf2941Dan Gohman "ComputeNumSignBits requires a TargetData object to operate " 885bd5ce52740700bb482fb2b5a03bce781acbf2941Dan Gohman "on non-integer values!"); 8866de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman const Type *Ty = V->getType(); 887bd5ce52740700bb482fb2b5a03bce781acbf2941Dan Gohman unsigned TyBits = TD ? TD->getTypeSizeInBits(V->getType()->getScalarType()) : 888bd5ce52740700bb482fb2b5a03bce781acbf2941Dan Gohman Ty->getScalarSizeInBits(); 889173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned Tmp, Tmp2; 890173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned FirstAnswer = 1; 891173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 892d82e511aec0ea27ddd4c1e504b37f689796e965fChris Lattner // Note that ConstantInt is handled by the general ComputeMaskedBits case 893d82e511aec0ea27ddd4c1e504b37f689796e965fChris Lattner // below. 894d82e511aec0ea27ddd4c1e504b37f689796e965fChris Lattner 895173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Depth == 6) 896173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return 1; // Limit search depth. 897173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 898ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman Operator *U = dyn_cast<Operator>(V); 899ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman switch (Operator::getOpcode(V)) { 900173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner default: break; 901173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::SExt: 90269a008075b29fbe0644ccbeecf1418ef8cca5e24Mon P Wang Tmp = TyBits - U->getOperand(0)->getType()->getScalarSizeInBits(); 903173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return ComputeNumSignBits(U->getOperand(0), TD, Depth+1) + Tmp; 904173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 905173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::AShr: 906173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 907173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // ashr X, C -> adds C sign bits. 908173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *C = dyn_cast<ConstantInt>(U->getOperand(1))) { 909173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp += C->getZExtValue(); 910173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp > TyBits) Tmp = TyBits; 911173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 9129a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman // vector ashr X, <C, C, C, C> -> adds C sign bits 9139a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman if (ConstantVector *C = dyn_cast<ConstantVector>(U->getOperand(1))) { 9149a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman if (ConstantInt *CI = dyn_cast_or_null<ConstantInt>(C->getSplatValue())) { 9159a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman Tmp += CI->getZExtValue(); 9169a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman if (Tmp > TyBits) Tmp = TyBits; 9179a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman } 9189a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman } 919173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return Tmp; 920173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Shl: 921173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *C = dyn_cast<ConstantInt>(U->getOperand(1))) { 922173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // shl destroys sign bits. 923173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 924173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (C->getZExtValue() >= TyBits || // Bad shift. 925173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner C->getZExtValue() >= Tmp) break; // Shifted all sign bits out. 926173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return Tmp - C->getZExtValue(); 927173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 928173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 929173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::And: 930173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Or: 931173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Xor: // NOT is handled here. 932173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Logical binary ops preserve the number of sign bits at the worst. 933173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 934173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp != 1) { 935173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); 936173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner FirstAnswer = std::min(Tmp, Tmp2); 937173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // We computed what we know about the sign bits as our first 938173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // answer. Now proceed to the generic code that uses 939173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // ComputeMaskedBits, and pick whichever answer is better. 940173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 941173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 942173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 943173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Select: 944173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); 945173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp == 1) return 1; // Early out. 946173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp2 = ComputeNumSignBits(U->getOperand(2), TD, Depth+1); 947173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return std::min(Tmp, Tmp2); 948173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 949173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Add: 950173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Add can have at most one carry bit. Thus we know that the output 951173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // is, at worst, one more bit than the inputs. 952173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 953173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp == 1) return 1; // Early out. 954173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 955173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Special case decrementing a value (ADD X, -1): 9560001e56f15215ae4bc5fffb82eec5c4828b888f0Dan Gohman if (ConstantInt *CRHS = dyn_cast<ConstantInt>(U->getOperand(1))) 957173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (CRHS->isAllOnesValue()) { 958173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0); 959173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask = APInt::getAllOnesValue(TyBits); 960173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(U->getOperand(0), Mask, KnownZero, KnownOne, TD, 961173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 962173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 963173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If the input is known to be 0 or 1, the output is 0/-1, which is all 964173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // sign bits set. 965173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if ((KnownZero | APInt(TyBits, 1)) == Mask) 966173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return TyBits; 967173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 968173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If we are subtracting one from a positive number, there is no carry 969173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // out of the result. 970173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero.isNegative()) 971173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return Tmp; 972173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 973173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 974173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); 975173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp2 == 1) return 1; 9768d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner return std::min(Tmp, Tmp2)-1; 977173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 978173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Sub: 979173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); 980173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp2 == 1) return 1; 981173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 982173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Handle NEG. 983173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *CLHS = dyn_cast<ConstantInt>(U->getOperand(0))) 984173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (CLHS->isNullValue()) { 985173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0); 986173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask = APInt::getAllOnesValue(TyBits); 987173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(U->getOperand(1), Mask, KnownZero, KnownOne, 988173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TD, Depth+1); 989173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If the input is known to be 0 or 1, the output is 0/-1, which is all 990173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // sign bits set. 991173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if ((KnownZero | APInt(TyBits, 1)) == Mask) 992173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return TyBits; 993173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 994173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If the input is known to be positive (the sign bit is known clear), 995173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // the output of the NEG has the same number of sign bits as the input. 996173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero.isNegative()) 997173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return Tmp2; 998173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 999173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Otherwise, we treat this like a SUB. 1000173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 1001173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 1002173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Sub can have at most one carry bit. Thus we know that the output 1003173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // is, at worst, one more bit than the inputs. 1004173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 1005173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp == 1) return 1; // Early out. 10068d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner return std::min(Tmp, Tmp2)-1; 10078d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner 10088d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner case Instruction::PHI: { 10098d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner PHINode *PN = cast<PHINode>(U); 10108d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner // Don't analyze large in-degree PHIs. 10118d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner if (PN->getNumIncomingValues() > 4) break; 10128d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner 10138d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner // Take the minimum of all incoming values. This can't infinitely loop 10148d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner // because of our depth threshold. 10158d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner Tmp = ComputeNumSignBits(PN->getIncomingValue(0), TD, Depth+1); 10168d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) { 10178d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner if (Tmp == 1) return Tmp; 10188d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner Tmp = std::min(Tmp, 10190af20d847ac89f797d613a8a4fc3e7127ccb0b36Evan Cheng ComputeNumSignBits(PN->getIncomingValue(i), TD, Depth+1)); 10208d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner } 10218d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner return Tmp; 10228d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner } 10238d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner 1024173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Trunc: 1025173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // FIXME: it's tricky to do anything useful for this, but it is an important 1026173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // case for targets like X86. 1027173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 1028173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 1029173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 1030173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Finally, if we can prove that the top bits of the result are 0's or 1's, 1031173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // use this information. 1032173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0); 1033173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask = APInt::getAllOnesValue(TyBits); 1034173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth); 1035173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 1036173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero.isNegative()) { // sign bit is 0 1037173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask = KnownZero; 1038173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } else if (KnownOne.isNegative()) { // sign bit is 1; 1039173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask = KnownOne; 1040173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } else { 1041173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Nothing known. 1042173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return FirstAnswer; 1043173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 1044173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 1045173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Okay, we know that the sign bit in Mask is set. Use CLZ to determine 1046173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // the number of identical bits in the top of the input value. 1047173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask = ~Mask; 1048173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask <<= Mask.getBitWidth()-TyBits; 1049173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Return # leading zeros. We use 'min' here in case Val was zero before 1050173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // shifting. We don't want to return '64' as for an i32 "0". 1051173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return std::max(FirstAnswer, std::min(TyBits, Mask.countLeadingZeros())); 1052173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner} 1053833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 10542b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez/// ComputeMultiple - This function computes the integer multiple of Base that 10552b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez/// equals V. If successful, it returns true and returns the multiple in 10563dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman/// Multiple. If unsuccessful, it returns false. It looks 10572b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez/// through SExt instructions only if LookThroughSExt is true. 10582b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandezbool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, 10593dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman bool LookThroughSExt, unsigned Depth) { 10602b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez const unsigned MaxDepth = 6; 10612b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10623dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman assert(V && "No Value?"); 10632b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez assert(Depth <= MaxDepth && "Limit Search Depth"); 1064b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands assert(V->getType()->isIntegerTy() && "Not integer or pointer type!"); 10652b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10662b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez const Type *T = V->getType(); 10672b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10683dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman ConstantInt *CI = dyn_cast<ConstantInt>(V); 10692b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10702b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Base == 0) 10712b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return false; 10722b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10732b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Base == 1) { 10742b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = V; 10752b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 10762b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 10772b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10782b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez ConstantExpr *CO = dyn_cast<ConstantExpr>(V); 10792b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Constant *BaseVal = ConstantInt::get(T, Base); 10802b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (CO && CO == BaseVal) { 10812b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // Multiple is 1. 10822b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = ConstantInt::get(T, 1); 10832b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 10842b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 10852b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10862b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (CI && CI->getZExtValue() % Base == 0) { 10872b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = ConstantInt::get(T, CI->getZExtValue() / Base); 10882b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 10892b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 10902b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10912b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Depth == MaxDepth) return false; // Limit search depth. 10922b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10932b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Operator *I = dyn_cast<Operator>(V); 10942b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (!I) return false; 10952b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10962b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez switch (I->getOpcode()) { 10972b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez default: break; 109811fe72661dac17efa1564ef6fc212acae4f0c07eChris Lattner case Instruction::SExt: 10992b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (!LookThroughSExt) return false; 11002b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // otherwise fall through to ZExt 110111fe72661dac17efa1564ef6fc212acae4f0c07eChris Lattner case Instruction::ZExt: 11023dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman return ComputeMultiple(I->getOperand(0), Base, Multiple, 11033dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman LookThroughSExt, Depth+1); 11042b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez case Instruction::Shl: 11052b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez case Instruction::Mul: { 11062b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Value *Op0 = I->getOperand(0); 11072b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Value *Op1 = I->getOperand(1); 11082b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 11092b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (I->getOpcode() == Instruction::Shl) { 11102b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1); 11112b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (!Op1CI) return false; 11122b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // Turn Op0 << Op1 into Op0 * 2^Op1 11132b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez APInt Op1Int = Op1CI->getValue(); 11142b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez uint64_t BitToSet = Op1Int.getLimitedValue(Op1Int.getBitWidth() - 1); 1115a99793c5ea24dd3839f4925b89b1f6acfcb24604Jay Foad APInt API(Op1Int.getBitWidth(), 0); 11167a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad API.setBit(BitToSet); 1117a99793c5ea24dd3839f4925b89b1f6acfcb24604Jay Foad Op1 = ConstantInt::get(V->getContext(), API); 11182b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11192b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 11202b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Value *Mul0 = NULL; 1121e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (ComputeMultiple(Op0, Base, Mul0, LookThroughSExt, Depth+1)) { 1122e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Constant *Op1C = dyn_cast<Constant>(Op1)) 1123e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Constant *MulC = dyn_cast<Constant>(Mul0)) { 1124e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Op1C->getType()->getPrimitiveSizeInBits() < 1125e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC->getType()->getPrimitiveSizeInBits()) 1126e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Op1C = ConstantExpr::getZExt(Op1C, MulC->getType()); 1127e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Op1C->getType()->getPrimitiveSizeInBits() > 1128e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC->getType()->getPrimitiveSizeInBits()) 1129e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC = ConstantExpr::getZExt(MulC, Op1C->getType()); 1130e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner 1131e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner // V == Base * (Mul0 * Op1), so return (Mul0 * Op1) 1132e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Multiple = ConstantExpr::getMul(MulC, Op1C); 1133e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner return true; 1134e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner } 11352b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 11362b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (ConstantInt *Mul0CI = dyn_cast<ConstantInt>(Mul0)) 11372b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Mul0CI->getValue() == 1) { 11382b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // V == Base * Op1, so return Op1 11392b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = Op1; 11402b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 11412b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11422b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11432b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 1144e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Value *Mul1 = NULL; 1145e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (ComputeMultiple(Op1, Base, Mul1, LookThroughSExt, Depth+1)) { 1146e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Constant *Op0C = dyn_cast<Constant>(Op0)) 1147e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Constant *MulC = dyn_cast<Constant>(Mul1)) { 1148e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Op0C->getType()->getPrimitiveSizeInBits() < 1149e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC->getType()->getPrimitiveSizeInBits()) 1150e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Op0C = ConstantExpr::getZExt(Op0C, MulC->getType()); 1151e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Op0C->getType()->getPrimitiveSizeInBits() > 1152e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC->getType()->getPrimitiveSizeInBits()) 1153e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC = ConstantExpr::getZExt(MulC, Op0C->getType()); 1154e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner 1155e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner // V == Base * (Mul1 * Op0), so return (Mul1 * Op0) 1156e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Multiple = ConstantExpr::getMul(MulC, Op0C); 1157e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner return true; 1158e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner } 11592b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 11602b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (ConstantInt *Mul1CI = dyn_cast<ConstantInt>(Mul1)) 11612b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Mul1CI->getValue() == 1) { 11622b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // V == Base * Op0, so return Op0 11632b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = Op0; 11642b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 11652b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11662b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11672b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11682b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11692b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 11702b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // We could not determine if V is a multiple of Base. 11712b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return false; 11722b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez} 11732b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 1174833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// CannotBeNegativeZero - Return true if we can prove that the specified FP 1175833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// value is never equal to -0.0. 1176833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// 1177833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// NOTE: this function will need to be revisited when we support non-default 1178833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// rounding modes! 1179833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// 1180833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattnerbool llvm::CannotBeNegativeZero(const Value *V, unsigned Depth) { 1181833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (const ConstantFP *CFP = dyn_cast<ConstantFP>(V)) 1182833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return !CFP->getValueAPF().isNegZero(); 1183833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1184833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (Depth == 6) 1185833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return 1; // Limit search depth. 1186833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1187ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman const Operator *I = dyn_cast<Operator>(V); 1188833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (I == 0) return false; 1189833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1190833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner // (add x, 0.0) is guaranteed to return +0.0, not -0.0. 1191ae3a0be92e33bc716722aa600983fc1535acb122Dan Gohman if (I->getOpcode() == Instruction::FAdd && 1192833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner isa<ConstantFP>(I->getOperand(1)) && 1193833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner cast<ConstantFP>(I->getOperand(1))->isNullValue()) 1194833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return true; 1195833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1196833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner // sitofp and uitofp turn into +0.0 for zero. 1197833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (isa<SIToFPInst>(I) || isa<UIToFPInst>(I)) 1198833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return true; 1199833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1200833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) 1201833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner // sqrt(-0.0) = -0.0, no other negative results are possible. 1202833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (II->getIntrinsicID() == Intrinsic::sqrt) 120371339c965ca6268b9bff91213364783c3d06f666Gabor Greif return CannotBeNegativeZero(II->getArgOperand(0), Depth+1); 1204833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1205833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (const CallInst *CI = dyn_cast<CallInst>(I)) 1206833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (const Function *F = CI->getCalledFunction()) { 1207833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (F->isDeclaration()) { 1208f0443c1eb44d737d9bd78962932fc80f74c6113cDaniel Dunbar // abs(x) != -0.0 1209f0443c1eb44d737d9bd78962932fc80f74c6113cDaniel Dunbar if (F->getName() == "abs") return true; 12109d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen // fabs[lf](x) != -0.0 12119d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen if (F->getName() == "fabs") return true; 12129d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen if (F->getName() == "fabsf") return true; 12139d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen if (F->getName() == "fabsl") return true; 12149d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen if (F->getName() == "sqrt" || F->getName() == "sqrtf" || 12159d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen F->getName() == "sqrtl") 121671339c965ca6268b9bff91213364783c3d06f666Gabor Greif return CannotBeNegativeZero(CI->getArgOperand(0), Depth+1); 1217833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner } 1218833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner } 1219833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1220833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return false; 1221833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner} 1222833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1223bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner/// isBytewiseValue - If the specified value can be set by repeating the same 1224bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner/// byte in memory, return the i8 value that it is represented with. This is 1225bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner/// true for all i8 values obviously, but is also true for i32 0, i32 -1, 1226bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner/// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated 1227bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner/// byte store (e.g. i16 0x1234), return null. 1228bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris LattnerValue *llvm::isBytewiseValue(Value *V) { 1229bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // All byte-wide stores are splatable, even of arbitrary variables. 1230bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (V->getType()->isIntegerTy(8)) return V; 123141bfbb0a8776674c486682cbf2aa80f15abfef68Chris Lattner 123241bfbb0a8776674c486682cbf2aa80f15abfef68Chris Lattner // Handle 'null' ConstantArrayZero etc. 123341bfbb0a8776674c486682cbf2aa80f15abfef68Chris Lattner if (Constant *C = dyn_cast<Constant>(V)) 123441bfbb0a8776674c486682cbf2aa80f15abfef68Chris Lattner if (C->isNullValue()) 123541bfbb0a8776674c486682cbf2aa80f15abfef68Chris Lattner return Constant::getNullValue(Type::getInt8Ty(V->getContext())); 1236bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1237bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // Constant float and double values can be handled as integer values if the 1238bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // corresponding integer value is "byteable". An important case is 0.0. 1239bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) { 1240bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (CFP->getType()->isFloatTy()) 1241bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner V = ConstantExpr::getBitCast(CFP, Type::getInt32Ty(V->getContext())); 1242bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (CFP->getType()->isDoubleTy()) 1243bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner V = ConstantExpr::getBitCast(CFP, Type::getInt64Ty(V->getContext())); 1244bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // Don't handle long double formats, which have strange constraints. 1245bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner } 1246bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1247bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // We can handle constant integers that are power of two in size and a 1248bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // multiple of 8 bits. 1249bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 1250bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner unsigned Width = CI->getBitWidth(); 1251bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (isPowerOf2_32(Width) && Width > 8) { 1252bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // We can handle this value if the recursive binary decomposition is the 1253bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // same at all levels. 1254bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner APInt Val = CI->getValue(); 1255bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner APInt Val2; 1256bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner while (Val.getBitWidth() != 8) { 1257bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner unsigned NextWidth = Val.getBitWidth()/2; 1258bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner Val2 = Val.lshr(NextWidth); 1259bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner Val2 = Val2.trunc(Val.getBitWidth()/2); 1260bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner Val = Val.trunc(Val.getBitWidth()/2); 1261bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1262bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // If the top/bottom halves aren't the same, reject it. 1263bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (Val != Val2) 1264bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return 0; 1265bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner } 1266bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return ConstantInt::get(V->getContext(), Val); 1267bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner } 1268bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner } 1269bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1270bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // A ConstantArray is splatable if all its members are equal and also 1271bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // splatable. 1272bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (ConstantArray *CA = dyn_cast<ConstantArray>(V)) { 1273bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (CA->getNumOperands() == 0) 1274bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return 0; 1275bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1276bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner Value *Val = isBytewiseValue(CA->getOperand(0)); 1277bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (!Val) 1278bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return 0; 1279bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1280bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner for (unsigned I = 1, E = CA->getNumOperands(); I != E; ++I) 1281bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (CA->getOperand(I-1) != CA->getOperand(I)) 1282bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return 0; 1283bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1284bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return Val; 1285bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner } 1286bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1287bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // Conceptually, we could handle things like: 1288bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // %a = zext i8 %X to i16 1289bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // %b = shl i16 %a, 8 1290bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // %c = or i16 %a, %b 1291bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // but until there is an example that actually needs this, it doesn't seem 1292bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // worth worrying about. 1293bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return 0; 1294bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner} 1295bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1296bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1297b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// This is the recursive version of BuildSubAggregate. It takes a few different 1298b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// arguments. Idxs is the index within the nested struct From that we are 1299b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// looking at now (which is of type IndexedType). IdxSkip is the number of 1300b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// indices from Idxs that should be left out when inserting into the resulting 1301b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// struct. To is the result struct built so far, new insertvalue instructions 1302b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// build on that. 13037db949df789383acce98ef072f08794fdd5bd04eDan Gohmanstatic Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType, 13047db949df789383acce98ef072f08794fdd5bd04eDan Gohman SmallVector<unsigned, 10> &Idxs, 13057db949df789383acce98ef072f08794fdd5bd04eDan Gohman unsigned IdxSkip, 13067db949df789383acce98ef072f08794fdd5bd04eDan Gohman Instruction *InsertBefore) { 1307b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman const llvm::StructType *STy = llvm::dyn_cast<llvm::StructType>(IndexedType); 1308b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (STy) { 13090a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Save the original To argument so we can modify it 13100a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman Value *OrigTo = To; 1311b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // General case, the type indexed by Idxs is a struct 1312b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { 1313b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Process each struct element recursively 1314b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman Idxs.push_back(i); 13150a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman Value *PrevTo = To; 1316710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip, 1317ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky InsertBefore); 1318b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman Idxs.pop_back(); 13190a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman if (!To) { 13200a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Couldn't find any inserted value for this index? Cleanup 13210a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman while (PrevTo != OrigTo) { 13220a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman InsertValueInst* Del = cast<InsertValueInst>(PrevTo); 13230a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman PrevTo = Del->getAggregateOperand(); 13240a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman Del->eraseFromParent(); 13250a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman } 13260a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Stop processing elements 13270a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman break; 13280a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman } 1329b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } 13300a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // If we succesfully found a value for each of our subaggregates 13310a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman if (To) 13320a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman return To; 1333b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } 13340a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Base case, the type indexed by SourceIdxs is not a struct, or not all of 13350a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // the struct's elements had a value that was inserted directly. In the latter 13360a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // case, perhaps we can't determine each of the subelements individually, but 13370a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // we might be able to find the complete struct somewhere. 13380a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman 13390a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Find the value that is at that particular spot 1340ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky Value *V = FindInsertedValue(From, Idxs.begin(), Idxs.end()); 13410a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman 13420a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman if (!V) 13430a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman return NULL; 13440a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman 13450a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Insert the value in the new (sub) aggregrate 13460a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman return llvm::InsertValueInst::Create(To, V, Idxs.begin() + IdxSkip, 13470a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman Idxs.end(), "tmp", InsertBefore); 1348b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman} 1349b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1350b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// This helper takes a nested struct and extracts a part of it (which is again a 1351b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// struct) into a new value. For example, given the struct: 1352b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// { a, { b, { c, d }, e } } 1353b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// and the indices "1, 1" this returns 1354b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// { c, d }. 1355b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// 13560a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// It does this by inserting an insertvalue for each element in the resulting 13570a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// struct, as opposed to just inserting a single struct. This will only work if 13580a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// each of the elements of the substruct are known (ie, inserted into From by an 13590a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// insertvalue instruction somewhere). 1360b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// 13610a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// All inserted insertvalue instructions are inserted before InsertBefore 13627db949df789383acce98ef072f08794fdd5bd04eDan Gohmanstatic Value *BuildSubAggregate(Value *From, const unsigned *idx_begin, 1363ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky const unsigned *idx_end, 13647db949df789383acce98ef072f08794fdd5bd04eDan Gohman Instruction *InsertBefore) { 1365977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman assert(InsertBefore && "Must have someplace to insert!"); 1366710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman const Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(), 1367710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman idx_begin, 1368710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman idx_end); 13699e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson Value *To = UndefValue::get(IndexedType); 1370b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman SmallVector<unsigned, 10> Idxs(idx_begin, idx_end); 1371b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman unsigned IdxSkip = Idxs.size(); 1372b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1373ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore); 1374b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman} 1375b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1376710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman/// FindInsertedValue - Given an aggregrate and an sequence of indices, see if 1377710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman/// the scalar value indexed is already around as a register, for example if it 1378710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman/// were inserted directly into the aggregrate. 13790a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman/// 13800a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman/// If InsertBefore is not null, this function will duplicate (modified) 13810a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman/// insertvalues when a part of a nested struct is extracted. 1382b23d5adbc8230167e711070b9298985de4580f30Matthijs KooijmanValue *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin, 1383ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky const unsigned *idx_end, Instruction *InsertBefore) { 1384b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Nothing to index? Just return V then (this is useful at the end of our 1385b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // recursion) 1386b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (idx_begin == idx_end) 1387b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman return V; 1388b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // We have indices, so V should have an indexable type 13891df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands assert((V->getType()->isStructTy() || V->getType()->isArrayTy()) 1390b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman && "Not looking at a struct or array?"); 1391b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman assert(ExtractValueInst::getIndexedType(V->getType(), idx_begin, idx_end) 1392b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman && "Invalid indices for type?"); 1393b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman const CompositeType *PTy = cast<CompositeType>(V->getType()); 139476f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson 1395b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (isa<UndefValue>(V)) 13969e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson return UndefValue::get(ExtractValueInst::getIndexedType(PTy, 1397b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman idx_begin, 1398b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman idx_end)); 1399b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman else if (isa<ConstantAggregateZero>(V)) 1400a7235ea7245028a0723e8ab7fd011386b3900777Owen Anderson return Constant::getNullValue(ExtractValueInst::getIndexedType(PTy, 140176f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson idx_begin, 140276f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson idx_end)); 1403b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman else if (Constant *C = dyn_cast<Constant>(V)) { 1404b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (isa<ConstantArray>(C) || isa<ConstantStruct>(C)) 1405b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Recursively process this constant 140676f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson return FindInsertedValue(C->getOperand(*idx_begin), idx_begin + 1, 1407ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky idx_end, InsertBefore); 1408b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } else if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) { 1409b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Loop the indices for the insertvalue instruction in parallel with the 1410b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // requested indices 1411b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman const unsigned *req_idx = idx_begin; 1412710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman for (const unsigned *i = I->idx_begin(), *e = I->idx_end(); 1413710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman i != e; ++i, ++req_idx) { 14149954c76f2c89ab3c70bfe8222534621a86f9085aDuncan Sands if (req_idx == idx_end) { 1415977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman if (InsertBefore) 14160a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // The requested index identifies a part of a nested aggregate. Handle 14170a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // this specially. For example, 14180a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %A = insertvalue { i32, {i32, i32 } } undef, i32 10, 1, 0 14190a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %B = insertvalue { i32, {i32, i32 } } %A, i32 11, 1, 1 14200a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %C = extractvalue {i32, { i32, i32 } } %B, 1 14210a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // This can be changed into 14220a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %A = insertvalue {i32, i32 } undef, i32 10, 0 14230a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %C = insertvalue {i32, i32 } %A, i32 11, 1 14240a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // which allows the unused 0,0 element from the nested struct to be 14250a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // removed. 1426ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky return BuildSubAggregate(V, idx_begin, req_idx, InsertBefore); 1427977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman else 1428977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman // We can't handle this without inserting insertvalues 1429977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman return 0; 14309954c76f2c89ab3c70bfe8222534621a86f9085aDuncan Sands } 1431b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1432b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // This insert value inserts something else than what we are looking for. 1433b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // See if the (aggregrate) value inserted into has the value we are 1434b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // looking for, then. 1435b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (*req_idx != *i) 1436710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman return FindInsertedValue(I->getAggregateOperand(), idx_begin, idx_end, 1437ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky InsertBefore); 1438b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } 1439b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // If we end up here, the indices of the insertvalue match with those 1440b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // requested (though possibly only partially). Now we recursively look at 1441b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // the inserted value, passing any remaining indices. 1442710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman return FindInsertedValue(I->getInsertedValueOperand(), req_idx, idx_end, 1443ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky InsertBefore); 1444b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } else if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) { 1445b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // If we're extracting a value from an aggregrate that was extracted from 1446b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // something else, we can extract from that something else directly instead. 1447b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // However, we will need to chain I's indices with the requested indices. 1448b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1449b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Calculate the number of indices required 1450b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman unsigned size = I->getNumIndices() + (idx_end - idx_begin); 1451b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Allocate some space to put the new indices in 14523faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman SmallVector<unsigned, 5> Idxs; 14533faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman Idxs.reserve(size); 1454b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Add indices from the extract value instruction 1455710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman for (const unsigned *i = I->idx_begin(), *e = I->idx_end(); 14563faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman i != e; ++i) 14573faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman Idxs.push_back(*i); 1458b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1459b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Add requested indices 14603faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman for (const unsigned *i = idx_begin, *e = idx_end; i != e; ++i) 14613faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman Idxs.push_back(*i); 1462b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 14633faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman assert(Idxs.size() == size 1464710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman && "Number of indices added not correct?"); 1465b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 14663faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman return FindInsertedValue(I->getAggregateOperand(), Idxs.begin(), Idxs.end(), 1467ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky InsertBefore); 1468b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } 1469b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Otherwise, we don't know (such as, extracting from a function return value 1470b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // or load instruction) 1471b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman return 0; 1472b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman} 14730ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 1474ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner/// GetPointerBaseWithConstantOffset - Analyze the specified pointer to see if 1475ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner/// it can be expressed as a base pointer plus a constant offset. Return the 1476ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner/// base and offset to the caller. 1477ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris LattnerValue *llvm::GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset, 1478ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner const TargetData &TD) { 1479ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner Operator *PtrOp = dyn_cast<Operator>(Ptr); 1480ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (PtrOp == 0) return Ptr; 1481ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1482ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // Just look through bitcasts. 1483ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (PtrOp->getOpcode() == Instruction::BitCast) 1484ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner return GetPointerBaseWithConstantOffset(PtrOp->getOperand(0), Offset, TD); 1485ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1486ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // If this is a GEP with constant indices, we can look through it. 1487ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner GEPOperator *GEP = dyn_cast<GEPOperator>(PtrOp); 1488ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (GEP == 0 || !GEP->hasAllConstantIndices()) return Ptr; 1489ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1490ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner gep_type_iterator GTI = gep_type_begin(GEP); 1491ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner for (User::op_iterator I = GEP->idx_begin(), E = GEP->idx_end(); I != E; 1492ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner ++I, ++GTI) { 1493ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner ConstantInt *OpC = cast<ConstantInt>(*I); 1494ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (OpC->isZero()) continue; 1495ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1496ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // Handle a struct and array indices which add their offset to the pointer. 1497ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (const StructType *STy = dyn_cast<StructType>(*GTI)) { 1498ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); 1499ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner } else { 1500ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); 1501ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner Offset += OpC->getSExtValue()*Size; 1502ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner } 1503ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner } 1504ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1505ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // Re-sign extend from the pointer size if needed to get overflow edge cases 1506ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // right. 1507ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner unsigned PtrSize = TD.getPointerSizeInBits(); 1508ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (PtrSize < 64) 1509ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner Offset = (Offset << (64-PtrSize)) >> (64-PtrSize); 1510ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1511ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner return GetPointerBaseWithConstantOffset(GEP->getPointerOperand(), Offset, TD); 1512ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner} 1513ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1514ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 15150ff39b3feb10477c224138156941234f5fa46f58Evan Cheng/// GetConstantStringInfo - This function computes the length of a 15160ff39b3feb10477c224138156941234f5fa46f58Evan Cheng/// null-terminated C string pointed to by V. If successful, it returns true 15170ff39b3feb10477c224138156941234f5fa46f58Evan Cheng/// and returns the string in Str. If unsuccessful, it returns false. 15180a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohmanbool llvm::GetConstantStringInfo(const Value *V, std::string &Str, 15190a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman uint64_t Offset, 15200582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling bool StopAtNul) { 15210582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling // If V is NULL then return false; 15220582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (V == NULL) return false; 15230ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15240ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Look through bitcast instructions. 15250a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman if (const BitCastInst *BCI = dyn_cast<BitCastInst>(V)) 15260582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return GetConstantStringInfo(BCI->getOperand(0), Str, Offset, StopAtNul); 15270582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling 15280ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // If the value is not a GEP instruction nor a constant expression with a 15290ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // GEP instruction, then return false because ConstantArray can't occur 15300ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // any other way 15310a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const User *GEP = 0; 15320a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) { 15330ff39b3feb10477c224138156941234f5fa46f58Evan Cheng GEP = GEPI; 15340a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 15350ff39b3feb10477c224138156941234f5fa46f58Evan Cheng if (CE->getOpcode() == Instruction::BitCast) 15360582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return GetConstantStringInfo(CE->getOperand(0), Str, Offset, StopAtNul); 15370582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (CE->getOpcode() != Instruction::GetElementPtr) 15380582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15390ff39b3feb10477c224138156941234f5fa46f58Evan Cheng GEP = CE; 15400ff39b3feb10477c224138156941234f5fa46f58Evan Cheng } 15410ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15420ff39b3feb10477c224138156941234f5fa46f58Evan Cheng if (GEP) { 15430ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Make sure the GEP has exactly three arguments. 15440582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (GEP->getNumOperands() != 3) 15450582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15460582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling 15470ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Make sure the index-ee is a pointer to array of i8. 15480ff39b3feb10477c224138156941234f5fa46f58Evan Cheng const PointerType *PT = cast<PointerType>(GEP->getOperand(0)->getType()); 15490ff39b3feb10477c224138156941234f5fa46f58Evan Cheng const ArrayType *AT = dyn_cast<ArrayType>(PT->getElementType()); 1550b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands if (AT == 0 || !AT->getElementType()->isIntegerTy(8)) 15510582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15520ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15530ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Check to make sure that the first operand of the GEP is an integer and 15540ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // has value 0 so that we are sure we're indexing into the initializer. 15550a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const ConstantInt *FirstIdx = dyn_cast<ConstantInt>(GEP->getOperand(1)); 15560582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (FirstIdx == 0 || !FirstIdx->isZero()) 15570582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15580ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15590ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // If the second index isn't a ConstantInt, then this is a variable index 15600ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // into the array. If this occurs, we can't say anything meaningful about 15610ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // the string. 15620ff39b3feb10477c224138156941234f5fa46f58Evan Cheng uint64_t StartIdx = 0; 15630a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman if (const ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2))) 15640ff39b3feb10477c224138156941234f5fa46f58Evan Cheng StartIdx = CI->getZExtValue(); 15650582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling else 15660582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15670582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return GetConstantStringInfo(GEP->getOperand(0), Str, StartIdx+Offset, 15680ff39b3feb10477c224138156941234f5fa46f58Evan Cheng StopAtNul); 15690ff39b3feb10477c224138156941234f5fa46f58Evan Cheng } 15700ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15710ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // The GEP instruction, constant or instruction, must reference a global 15720ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // variable that is a constant and is initialized. The referenced constant 15730ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // initializer is the array that we'll use for optimization. 15740a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const GlobalVariable* GV = dyn_cast<GlobalVariable>(V); 15758255573835970e7130ba93271972172fb335f2ecDan Gohman if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer()) 15760582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15770a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const Constant *GlobalInit = GV->getInitializer(); 15780ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15790ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Handle the ConstantAggregateZero case 15800582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (isa<ConstantAggregateZero>(GlobalInit)) { 15810ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // This is a degenerate case. The initializer is constant zero so the 15820ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // length of the string must be zero. 15830582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling Str.clear(); 15840582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return true; 15850582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling } 15860ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15870ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Must be a Constant Array 15880a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit); 1589b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands if (Array == 0 || !Array->getType()->getElementType()->isIntegerTy(8)) 15900582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15910ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15920ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Get the number of elements in the array 15930ff39b3feb10477c224138156941234f5fa46f58Evan Cheng uint64_t NumElts = Array->getType()->getNumElements(); 15940ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15950582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (Offset > NumElts) 15960582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15970ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15980ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Traverse the constant array from 'Offset' which is the place the GEP refers 15990ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // to in the array. 16000582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling Str.reserve(NumElts-Offset); 16010ff39b3feb10477c224138156941234f5fa46f58Evan Cheng for (unsigned i = Offset; i != NumElts; ++i) { 16020a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const Constant *Elt = Array->getOperand(i); 16030a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const ConstantInt *CI = dyn_cast<ConstantInt>(Elt); 16040582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (!CI) // This array isn't suitable, non-int initializer. 16050582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 16060ff39b3feb10477c224138156941234f5fa46f58Evan Cheng if (StopAtNul && CI->isZero()) 16070582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return true; // we found end of string, success! 16080582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling Str += (char)CI->getZExtValue(); 16090ff39b3feb10477c224138156941234f5fa46f58Evan Cheng } 16100582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling 16110ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // The array isn't null terminated, but maybe this is a memcpy, not a strcpy. 16120582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return true; 16130ff39b3feb10477c224138156941234f5fa46f58Evan Cheng} 161425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 161525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher// These next two are very similar to the above, but also look through PHI 161625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher// nodes. 161725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher// TODO: See if we can integrate these two together. 161825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 161925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher/// GetStringLengthH - If we can compute the length of the string pointed to by 162025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher/// the specified pointer, return 'len+1'. If we can't, return 0. 162125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopherstatic uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) { 162225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Look through noop bitcast instructions. 162325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (BitCastInst *BCI = dyn_cast<BitCastInst>(V)) 162425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return GetStringLengthH(BCI->getOperand(0), PHIs); 162525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 162625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If this is a PHI node, there are two cases: either we have already seen it 162725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // or we haven't. 162825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (PHINode *PN = dyn_cast<PHINode>(V)) { 162925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!PHIs.insert(PN)) 163025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return ~0ULL; // already in the set. 163125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 163225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If it was new, see if all the input strings are the same length. 163325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t LenSoFar = ~0ULL; 163425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 163525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs); 163625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len == 0) return 0; // Unknown length -> unknown. 163725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 163825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len == ~0ULL) continue; 163925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 164025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len != LenSoFar && LenSoFar != ~0ULL) 164125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; // Disagree -> unknown. 164225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher LenSoFar = Len; 164325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 164425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 164525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Success, all agree. 164625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return LenSoFar; 164725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 164825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 164925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y) 165025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (SelectInst *SI = dyn_cast<SelectInst>(V)) { 165125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs); 165225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len1 == 0) return 0; 165325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs); 165425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len2 == 0) return 0; 165525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len1 == ~0ULL) return Len2; 165625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len2 == ~0ULL) return Len1; 165725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len1 != Len2) return 0; 165825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return Len1; 165925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 166025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 166125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If the value is not a GEP instruction nor a constant expression with a 166225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // GEP instruction, then return unknown. 166325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher User *GEP = 0; 166425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) { 166525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher GEP = GEPI; 166625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 166725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (CE->getOpcode() != Instruction::GetElementPtr) 166825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 166925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher GEP = CE; 167025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } else { 167125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 167225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 167325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 167425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Make sure the GEP has exactly three arguments. 167525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (GEP->getNumOperands() != 3) 167625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 167725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 167825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Check to make sure that the first operand of the GEP is an integer and 167925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // has value 0 so that we are sure we're indexing into the initializer. 168025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) { 168125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!Idx->isZero()) 168225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 168325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } else 168425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 168525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 168625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If the second index isn't a ConstantInt, then this is a variable index 168725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // into the array. If this occurs, we can't say anything meaningful about 168825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // the string. 168925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t StartIdx = 0; 169025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2))) 169125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher StartIdx = CI->getZExtValue(); 169225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher else 169325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 169425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 169525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // The GEP instruction, constant or instruction, must reference a global 169625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // variable that is a constant and is initialized. The referenced constant 169725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // initializer is the array that we'll use for optimization. 169825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)); 169925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!GV || !GV->isConstant() || !GV->hasInitializer() || 170025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher GV->mayBeOverridden()) 170125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 170225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher Constant *GlobalInit = GV->getInitializer(); 170325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 170425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Handle the ConstantAggregateZero case, which is a degenerate case. The 170525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // initializer is constant zero so the length of the string must be zero. 170625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (isa<ConstantAggregateZero>(GlobalInit)) 170725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 1; // Len = 0 offset by 1. 170825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 170925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Must be a Constant Array 171025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit); 171125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!Array || !Array->getType()->getElementType()->isIntegerTy(8)) 171225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return false; 171325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 171425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Get the number of elements in the array 171525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t NumElts = Array->getType()->getNumElements(); 171625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 171725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Traverse the constant array from StartIdx (derived above) which is 171825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // the place the GEP refers to in the array. 171925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher for (unsigned i = StartIdx; i != NumElts; ++i) { 172025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher Constant *Elt = Array->getOperand(i); 172125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher ConstantInt *CI = dyn_cast<ConstantInt>(Elt); 172225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!CI) // This array isn't suitable, non-int initializer. 172325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 172425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (CI->isZero()) 172525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return i-StartIdx+1; // We found end of string, success! 172625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 172725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 172825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; // The array isn't null terminated, conservatively return 'unknown'. 172925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher} 173025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 173125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher/// GetStringLength - If we can compute the length of the string pointed to by 173225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher/// the specified pointer, return 'len+1'. If we can't, return 0. 173325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopheruint64_t llvm::GetStringLength(Value *V) { 173425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!V->getType()->isPointerTy()) return 0; 173525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 173625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher SmallPtrSet<PHINode*, 32> PHIs; 173725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t Len = GetStringLengthH(V, PHIs); 173825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return 173925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // an empty string as a length. 174025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return Len == ~0ULL ? 1 : Len; 174125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher} 17425034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman 1743bd1801b5553c8be3960255a92738464e0010b6f6Dan GohmanValue * 1744bd1801b5553c8be3960255a92738464e0010b6f6Dan Gohmanllvm::GetUnderlyingObject(Value *V, const TargetData *TD, unsigned MaxLookup) { 17455034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman if (!V->getType()->isPointerTy()) 17465034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman return V; 17475034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) { 17485034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { 17495034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman V = GEP->getPointerOperand(); 17505034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } else if (Operator::getOpcode(V) == Instruction::BitCast) { 17515034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman V = cast<Operator>(V)->getOperand(0); 17525034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { 17535034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman if (GA->mayBeOverridden()) 17545034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman return V; 17555034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman V = GA->getAliasee(); 17565034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } else { 1757c01895c7db4c4d8883dd4c31427c42cdae356567Dan Gohman // See if InstructionSimplify knows any relevant tricks. 1758c01895c7db4c4d8883dd4c31427c42cdae356567Dan Gohman if (Instruction *I = dyn_cast<Instruction>(V)) 1759bd1801b5553c8be3960255a92738464e0010b6f6Dan Gohman // TODO: Aquire a DominatorTree and use it. 1760bd1801b5553c8be3960255a92738464e0010b6f6Dan Gohman if (Value *Simplified = SimplifyInstruction(I, TD, 0)) { 1761c01895c7db4c4d8883dd4c31427c42cdae356567Dan Gohman V = Simplified; 1762c01895c7db4c4d8883dd4c31427c42cdae356567Dan Gohman continue; 1763c01895c7db4c4d8883dd4c31427c42cdae356567Dan Gohman } 1764c01895c7db4c4d8883dd4c31427c42cdae356567Dan Gohman 17655034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman return V; 17665034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } 17675034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman assert(V->getType()->isPointerTy() && "Unexpected operand type!"); 17685034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } 17695034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman return V; 17705034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman} 1771