ValueTracking.cpp revision c14bc77315ac4867f16c1585181b41919339eb3c
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 } 432173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 433173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 434173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::SRem: 435173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { 436cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands APInt RA = Rem->getValue().abs(); 437cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands if (RA.isPowerOf2()) { 438cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands APInt LowBits = RA - 1; 439173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2 = LowBits | APInt::getSignBit(BitWidth); 440173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD, 441173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 442173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 443cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // The low bits of the first operand are unchanged by the srem. 444cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownZero = KnownZero2 & LowBits; 445cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownOne = KnownOne2 & LowBits; 446cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands 447cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // If the first operand is non-negative or has all low bits zero, then 448cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // the upper bits are all zero. 449173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero2[BitWidth-1] || ((KnownZero2 & LowBits) == LowBits)) 450cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownZero |= ~LowBits; 451173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 452cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // If the first operand is negative and not all low bits are zero, then 453cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // the upper bits are all one. 454cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands if (KnownOne2[BitWidth-1] && ((KnownOne2 & LowBits) != 0)) 455cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownOne |= ~LowBits; 456cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands 457cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownZero &= Mask; 458cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownOne &= Mask; 459173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 460ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 461173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 462173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 463c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky 464c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky // The sign bit is the LHS's sign bit, except when the result of the 465c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky // remainder is zero. 466c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky if (Mask.isNegative() && KnownZero.isNonNegative()) { 467c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky APInt Mask2 = APInt::getSignBit(BitWidth); 468c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0); 469c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky ComputeMaskedBits(I->getOperand(0), Mask2, LHSKnownZero, LHSKnownOne, TD, 470c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky Depth+1); 471c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky // If it's known zero, our sign bit is also zero. 472c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky if (LHSKnownZero.isNegative()) 473c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky KnownZero |= LHSKnownZero; 474c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky } 475c14bc77315ac4867f16c1585181b41919339eb3cNick Lewycky 476173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 477173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::URem: { 478173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { 479173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt RA = Rem->getValue(); 480173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (RA.isPowerOf2()) { 481173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt LowBits = (RA - 1); 482173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2 = LowBits & Mask; 483173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= ~LowBits & Mask; 484173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, TD, 485173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 486ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 487173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 488173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 489173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 490173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 491173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Since the result is less than or equal to either operand, any leading 492173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // zero bits in either operand must also exist in the result. 493173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt AllOnes = APInt::getAllOnesValue(BitWidth); 494173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), AllOnes, KnownZero, KnownOne, 495173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TD, Depth+1); 496173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), AllOnes, KnownZero2, KnownOne2, 497173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TD, Depth+1); 498173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 49979abedb83a4dd7d3583c7ca6df8283079acc3ba5Chris Lattner unsigned Leaders = std::max(KnownZero.countLeadingOnes(), 500173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero2.countLeadingOnes()); 5017a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownOne.clearAllBits(); 502173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getHighBitsSet(BitWidth, Leaders) & Mask; 503173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 504173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 505173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 506a276c603b82a11b0bf0b59f0517a69e4b63adeabVictor Hernandez case Instruction::Alloca: { 5077b929dad59785f62a66f7c58615082f98441e95eVictor Hernandez AllocaInst *AI = cast<AllocaInst>(V); 508173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned Align = AI->getAlignment(); 509a276c603b82a11b0bf0b59f0517a69e4b63adeabVictor Hernandez if (Align == 0 && TD) 510a276c603b82a11b0bf0b59f0517a69e4b63adeabVictor Hernandez Align = TD->getABITypeAlignment(AI->getType()->getElementType()); 511173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 512173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Align > 0) 513173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = Mask & APInt::getLowBitsSet(BitWidth, 514173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner CountTrailingZeros_32(Align)); 515173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 516173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 517173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::GetElementPtr: { 518173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Analyze all of the subscripts of this getelementptr instruction 519173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // to determine if we can prove known low zero bits. 520173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt LocalMask = APInt::getAllOnesValue(BitWidth); 521173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt LocalKnownZero(BitWidth, 0), LocalKnownOne(BitWidth, 0); 522173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), LocalMask, 523173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LocalKnownZero, LocalKnownOne, TD, Depth+1); 524173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned TrailZ = LocalKnownZero.countTrailingOnes(); 525173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 526173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner gep_type_iterator GTI = gep_type_begin(I); 527173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i, ++GTI) { 528173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *Index = I->getOperand(i); 529173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (const StructType *STy = dyn_cast<StructType>(*GTI)) { 530173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Handle struct member offset arithmetic. 531173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!TD) return; 532173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner const StructLayout *SL = TD->getStructLayout(STy); 533173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned Idx = cast<ConstantInt>(Index)->getZExtValue(); 534173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner uint64_t Offset = SL->getElementOffset(Idx); 535173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TrailZ = std::min(TrailZ, 536173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner CountTrailingZeros_64(Offset)); 537173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } else { 538173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Handle array index arithmetic. 539173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner const Type *IndexedTy = GTI.getIndexedType(); 540173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!IndexedTy->isSized()) return; 5416de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman unsigned GEPOpiBits = Index->getType()->getScalarSizeInBits(); 542777d2306b36816a53bc1ae1244c0dc7d998ae691Duncan Sands uint64_t TypeSize = TD ? TD->getTypeAllocSize(IndexedTy) : 1; 543173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LocalMask = APInt::getAllOnesValue(GEPOpiBits); 544173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LocalKnownZero = LocalKnownOne = APInt(GEPOpiBits, 0); 545173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(Index, LocalMask, 546173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LocalKnownZero, LocalKnownOne, TD, Depth+1); 547173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TrailZ = std::min(TrailZ, 54879abedb83a4dd7d3583c7ca6df8283079acc3ba5Chris Lattner unsigned(CountTrailingZeros_64(TypeSize) + 54979abedb83a4dd7d3583c7ca6df8283079acc3ba5Chris Lattner LocalKnownZero.countTrailingOnes())); 550173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 551173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 552173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 553173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getLowBitsSet(BitWidth, TrailZ) & Mask; 554173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 555173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 556173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::PHI: { 557173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner PHINode *P = cast<PHINode>(I); 558173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Handle the case of a simple two-predecessor recurrence PHI. 559173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // There's a lot more that could theoretically be done here, but 560173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // this is sufficient to catch some interesting cases. 561173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (P->getNumIncomingValues() == 2) { 562173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner for (unsigned i = 0; i != 2; ++i) { 563173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *L = P->getIncomingValue(i); 564173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *R = P->getIncomingValue(!i); 565ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman Operator *LU = dyn_cast<Operator>(L); 566173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!LU) 567173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner continue; 568ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman unsigned Opcode = LU->getOpcode(); 569173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Check for operations that have the property that if 570173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // both their operands have low zero bits, the result 571173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // will have low zero bits. 572173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Opcode == Instruction::Add || 573173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Opcode == Instruction::Sub || 574173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Opcode == Instruction::And || 575173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Opcode == Instruction::Or || 576173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Opcode == Instruction::Mul) { 577173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *LL = LU->getOperand(0); 578173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *LR = LU->getOperand(1); 579173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Find a recurrence. 580173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (LL == I) 581173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner L = LR; 582173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner else if (LR == I) 583173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner L = LL; 584173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner else 585173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 586173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Ok, we have a PHI of the form L op= R. Check for low 587173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // zero bits. 588173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2 = APInt::getAllOnesValue(BitWidth); 589173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(R, Mask2, KnownZero2, KnownOne2, TD, Depth+1); 590173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask2 = APInt::getLowBitsSet(BitWidth, 591173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero2.countTrailingOnes()); 592c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene 593c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene // We need to take the minimum number of known bits 594c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene APInt KnownZero3(KnownZero), KnownOne3(KnownOne); 595c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene ComputeMaskedBits(L, Mask2, KnownZero3, KnownOne3, TD, Depth+1); 596c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene 597173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = Mask & 598173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt::getLowBitsSet(BitWidth, 599c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene std::min(KnownZero2.countTrailingOnes(), 600c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene KnownZero3.countTrailingOnes())); 601173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 602173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 603173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 604173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 6059004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman 6063b739d278c87f8ac22b5dc368b319fa278347b2fNick Lewycky // Unreachable blocks may have zero-operand PHI nodes. 6073b739d278c87f8ac22b5dc368b319fa278347b2fNick Lewycky if (P->getNumIncomingValues() == 0) 6083b739d278c87f8ac22b5dc368b319fa278347b2fNick Lewycky return; 6093b739d278c87f8ac22b5dc368b319fa278347b2fNick Lewycky 6109004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // Otherwise take the unions of the known bit sets of the operands, 6119004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // taking conservative care to avoid excessive recursion. 6129004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman if (Depth < MaxDepth - 1 && !KnownZero && !KnownOne) { 6139004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownZero = APInt::getAllOnesValue(BitWidth); 6149004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownOne = APInt::getAllOnesValue(BitWidth); 6159004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman for (unsigned i = 0, e = P->getNumIncomingValues(); i != e; ++i) { 6169004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // Skip direct self references. 6179004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman if (P->getIncomingValue(i) == P) continue; 6189004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman 6199004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownZero2 = APInt(BitWidth, 0); 6209004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownOne2 = APInt(BitWidth, 0); 6219004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // Recurse, but cap the recursion to one level, because we don't 6229004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // want to waste time spinning around in loops. 6239004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman ComputeMaskedBits(P->getIncomingValue(i), KnownZero | KnownOne, 6249004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownZero2, KnownOne2, TD, MaxDepth-1); 6259004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownZero &= KnownZero2; 6269004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownOne &= KnownOne2; 6279004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // If all bits have been ruled out, there's no need to check 6289004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // more operands. 6299004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman if (!KnownZero && !KnownOne) 6309004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman break; 6319004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman } 6329004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman } 633173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 634173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 635173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Call: 636173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) { 637173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner switch (II->getIntrinsicID()) { 638173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner default: break; 639173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Intrinsic::ctpop: 640173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Intrinsic::ctlz: 641173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Intrinsic::cttz: { 642173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned LowBits = Log2_32(BitWidth)+1; 643173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getHighBitsSet(BitWidth, BitWidth - LowBits); 644173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 645173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 646173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 647173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 648173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 649173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 650173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner} 651173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 652d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// ComputeSignBit - Determine whether the sign bit is known to be zero or 653d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// one. Convenience wrapper around ComputeMaskedBits. 654d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sandsvoid llvm::ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne, 655d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands const TargetData *TD, unsigned Depth) { 656d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands unsigned BitWidth = getBitWidth(V->getType(), TD); 657d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (!BitWidth) { 658d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands KnownZero = false; 659d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands KnownOne = false; 660d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return; 661d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 662d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt ZeroBits(BitWidth, 0); 663d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt OneBits(BitWidth, 0); 664d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeMaskedBits(V, APInt::getSignBit(BitWidth), ZeroBits, OneBits, TD, 665d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands Depth); 666d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands KnownOne = OneBits[BitWidth - 1]; 667d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands KnownZero = ZeroBits[BitWidth - 1]; 668d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands} 669d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 670d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// isPowerOfTwo - Return true if the given value is known to have exactly one 671d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// bit set when defined. For vectors return true if every element is known to 672d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// be a power of two when defined. Supports values with integer or pointer 673d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// types and vectors of integers. 674d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sandsbool llvm::isPowerOfTwo(Value *V, const TargetData *TD, unsigned Depth) { 675d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) 676464a4f349c95a25d06d709e79d7df21fbbb155e2Duncan Sands return CI->getValue().isPowerOf2(); 677d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // TODO: Handle vector constants. 678d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 679d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // 1 << X is clearly a power of two if the one is not shifted off the end. If 680d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // it is shifted off the end then the result is undefined. 681d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (match(V, m_Shl(m_One(), m_Value()))) 682d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 683d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 684d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // (signbit) >>l X is clearly a power of two if the one is not shifted off the 685d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // bottom. If it is shifted off the bottom then the result is undefined. 68693c780288df9631d11f996b010b2212a8b44d4d3Duncan Sands if (match(V, m_LShr(m_SignBit(), m_Value()))) 687d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 688d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 689d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // The remaining tests are all recursive, so bail out if we hit the limit. 690d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (Depth++ == MaxDepth) 691d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return false; 692d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 693d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (ZExtInst *ZI = dyn_cast<ZExtInst>(V)) 694d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return isPowerOfTwo(ZI->getOperand(0), TD, Depth); 695d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 696d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (SelectInst *SI = dyn_cast<SelectInst>(V)) 697d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return isPowerOfTwo(SI->getTrueValue(), TD, Depth) && 698d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands isPowerOfTwo(SI->getFalseValue(), TD, Depth); 699d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 7003dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky // An exact divide or right shift can only shift off zero bits, so the result 701da834093b73ff67ede909f2ac616e0703ac6ce8eNick Lewycky // is a power of two only if the first operand is a power of two. 7023dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky if (match(V, m_Shr(m_Value(), m_Value())) || 7033dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky match(V, m_IDiv(m_Value(), m_Value()))) { 7043dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky BinaryOperator *BO = cast<BinaryOperator>(V); 7053dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky if (BO->isExact()) 7063dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky return isPowerOfTwo(BO->getOperand(0), TD, Depth); 7073dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky } 7083dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky 709d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return false; 710d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands} 711d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 712d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// isKnownNonZero - Return true if the given value is known to be non-zero 713d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// when defined. For vectors return true if every element is known to be 714d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// non-zero when defined. Supports values with integer or pointer type and 715d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands/// vectors of integers. 716d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sandsbool llvm::isKnownNonZero(Value *V, const TargetData *TD, unsigned Depth) { 717d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (Constant *C = dyn_cast<Constant>(V)) { 718d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (C->isNullValue()) 719d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return false; 720d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (isa<ConstantInt>(C)) 721d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // Must be non-zero due to null test above. 722d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 723d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // TODO: Handle vectors 724d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return false; 725d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 726d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 727d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // The remaining tests are all recursive, so bail out if we hit the limit. 728d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (Depth++ == MaxDepth) 729d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return false; 730d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 731d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands unsigned BitWidth = getBitWidth(V->getType(), TD); 732d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 733d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // X | Y != 0 if X != 0 or Y != 0. 734d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands Value *X = 0, *Y = 0; 735d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (match(V, m_Or(m_Value(X), m_Value(Y)))) 736d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return isKnownNonZero(X, TD, Depth) || isKnownNonZero(Y, TD, Depth); 737d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 738d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // ext X != 0 if X != 0. 739d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (isa<SExtInst>(V) || isa<ZExtInst>(V)) 740d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return isKnownNonZero(cast<Instruction>(V)->getOperand(0), TD, Depth); 741d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 7429136782d273cd45b6f19a7d0cc0d146d0791bac9Duncan Sands // shl X, Y != 0 if X is odd. Note that the value of the shift is undefined 743d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // if the lowest bit is shifted off the end. 744d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (BitWidth && match(V, m_Shl(m_Value(X), m_Value(Y)))) { 7453dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky // shl nuw can't remove any non-zero bits. 7463dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky BinaryOperator *BO = cast<BinaryOperator>(V); 7473dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky if (BO->hasNoUnsignedWrap()) 7483dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky return isKnownNonZero(X, TD, Depth); 7493dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky 750d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt KnownZero(BitWidth, 0); 751d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt KnownOne(BitWidth, 0); 7529136782d273cd45b6f19a7d0cc0d146d0791bac9Duncan Sands ComputeMaskedBits(X, APInt(BitWidth, 1), KnownZero, KnownOne, TD, Depth); 753d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (KnownOne[0]) 754d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 755d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 7569136782d273cd45b6f19a7d0cc0d146d0791bac9Duncan Sands // shr X, Y != 0 if X is negative. Note that the value of the shift is not 757d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // defined if the sign bit is shifted off the end. 758d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands else if (match(V, m_Shr(m_Value(X), m_Value(Y)))) { 7593dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky // shr exact can only shift out zero bits. 7603dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky BinaryOperator *BO = cast<BinaryOperator>(V); 7613dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky if (BO->isExact()) 7623dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky return isKnownNonZero(X, TD, Depth); 7633dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky 764d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands bool XKnownNonNegative, XKnownNegative; 765d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeSignBit(X, XKnownNonNegative, XKnownNegative, TD, Depth); 766d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (XKnownNegative) 767d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 768d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 7693dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky // div exact can only produce a zero if the dividend is zero. 7703dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky else if (match(V, m_IDiv(m_Value(X), m_Value()))) { 7713dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky BinaryOperator *BO = cast<BinaryOperator>(V); 7723dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky if (BO->isExact()) 7733dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky return isKnownNonZero(X, TD, Depth); 7743dfd98744c1f6e6c5d13e419b63ac69894ae84cfNick Lewycky } 775d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // X + Y. 776d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands else if (match(V, m_Add(m_Value(X), m_Value(Y)))) { 777d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands bool XKnownNonNegative, XKnownNegative; 778d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands bool YKnownNonNegative, YKnownNegative; 779d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeSignBit(X, XKnownNonNegative, XKnownNegative, TD, Depth); 780d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeSignBit(Y, YKnownNonNegative, YKnownNegative, TD, Depth); 781d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 782d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // If X and Y are both non-negative (as signed values) then their sum is not 783227fba11ca168225d913d1cea94a05b883092e76Duncan Sands // zero unless both X and Y are zero. 784d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (XKnownNonNegative && YKnownNonNegative) 785227fba11ca168225d913d1cea94a05b883092e76Duncan Sands if (isKnownNonZero(X, TD, Depth) || isKnownNonZero(Y, TD, Depth)) 786227fba11ca168225d913d1cea94a05b883092e76Duncan Sands return true; 787d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 788d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // If X and Y are both negative (as signed values) then their sum is not 789d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // zero unless both X and Y equal INT_MIN. 790d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (BitWidth && XKnownNegative && YKnownNegative) { 791d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt KnownZero(BitWidth, 0); 792d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt KnownOne(BitWidth, 0); 793d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt Mask = APInt::getSignedMaxValue(BitWidth); 794d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // The sign bit of X is set. If some other bit is set then X is not equal 795d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // to INT_MIN. 796d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeMaskedBits(X, Mask, KnownZero, KnownOne, TD, Depth); 797d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if ((KnownOne & Mask) != 0) 798d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 799d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // The sign bit of Y is set. If some other bit is set then Y is not equal 800d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // to INT_MIN. 801d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeMaskedBits(Y, Mask, KnownZero, KnownOne, TD, Depth); 802d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if ((KnownOne & Mask) != 0) 803d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 804d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 805d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 806d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // The sum of a non-negative number and a power of two is not zero. 807d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (XKnownNonNegative && isPowerOfTwo(Y, TD, Depth)) 808d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 809d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (YKnownNonNegative && isPowerOfTwo(X, TD, Depth)) 810d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 811d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 812d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands // (C ? X : Y) != 0 if X != 0 and Y != 0. 813d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands else if (SelectInst *SI = dyn_cast<SelectInst>(V)) { 814d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (isKnownNonZero(SI->getTrueValue(), TD, Depth) && 815d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands isKnownNonZero(SI->getFalseValue(), TD, Depth)) 816d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return true; 817d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands } 818d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 819d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands if (!BitWidth) return false; 820d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt KnownZero(BitWidth, 0); 821d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands APInt KnownOne(BitWidth, 0); 822d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands ComputeMaskedBits(V, APInt::getAllOnesValue(BitWidth), KnownZero, KnownOne, 823d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands TD, Depth); 824d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands return KnownOne != 0; 825d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands} 826d70d1a5c44609af091f6fc3e29193f9f4756a74fDuncan Sands 827173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use 828173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// this predicate to simplify operations downstream. Mask is known to be zero 829173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// for bits that V cannot have. 830cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// 831cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// This function is defined on values with integer type, values with pointer 832cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// type (but only if TD is non-null), and vectors of integers. In the case 833cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// where V is a vector, the mask, known zero, and known one values are the 834cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// same width as the vector element, and the bit is set only if it is true 835cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// for all of the elements in the vector. 836173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattnerbool llvm::MaskedValueIsZero(Value *V, const APInt &Mask, 837846a2f2703f6bb894098274964faf5dce0b68c4dDan Gohman const TargetData *TD, unsigned Depth) { 838173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero(Mask.getBitWidth(), 0), KnownOne(Mask.getBitWidth(), 0); 839173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth); 840173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 841173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return (KnownZero & Mask) == Mask; 842173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner} 843173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 844173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 845173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 846173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// ComputeNumSignBits - Return the number of times the sign bit of the 847173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// register is replicated into the other bits. We know that at least 1 bit 848173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// is always equal to the sign bit (itself), but other cases can give us 849173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// information. For example, immediately after an "ashr X, 2", we know that 850173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// the top 3 bits are all equal to each other, so we return 3. 851173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// 852173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// 'Op' must have a scalar integer type. 853173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// 854846a2f2703f6bb894098274964faf5dce0b68c4dDan Gohmanunsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD, 855846a2f2703f6bb894098274964faf5dce0b68c4dDan Gohman unsigned Depth) { 856b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands assert((TD || V->getType()->isIntOrIntVectorTy()) && 857bd5ce52740700bb482fb2b5a03bce781acbf2941Dan Gohman "ComputeNumSignBits requires a TargetData object to operate " 858bd5ce52740700bb482fb2b5a03bce781acbf2941Dan Gohman "on non-integer values!"); 8596de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman const Type *Ty = V->getType(); 860bd5ce52740700bb482fb2b5a03bce781acbf2941Dan Gohman unsigned TyBits = TD ? TD->getTypeSizeInBits(V->getType()->getScalarType()) : 861bd5ce52740700bb482fb2b5a03bce781acbf2941Dan Gohman Ty->getScalarSizeInBits(); 862173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned Tmp, Tmp2; 863173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned FirstAnswer = 1; 864173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 865d82e511aec0ea27ddd4c1e504b37f689796e965fChris Lattner // Note that ConstantInt is handled by the general ComputeMaskedBits case 866d82e511aec0ea27ddd4c1e504b37f689796e965fChris Lattner // below. 867d82e511aec0ea27ddd4c1e504b37f689796e965fChris Lattner 868173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Depth == 6) 869173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return 1; // Limit search depth. 870173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 871ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman Operator *U = dyn_cast<Operator>(V); 872ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman switch (Operator::getOpcode(V)) { 873173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner default: break; 874173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::SExt: 87569a008075b29fbe0644ccbeecf1418ef8cca5e24Mon P Wang Tmp = TyBits - U->getOperand(0)->getType()->getScalarSizeInBits(); 876173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return ComputeNumSignBits(U->getOperand(0), TD, Depth+1) + Tmp; 877173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 878173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::AShr: 879173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 880173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // ashr X, C -> adds C sign bits. 881173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *C = dyn_cast<ConstantInt>(U->getOperand(1))) { 882173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp += C->getZExtValue(); 883173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp > TyBits) Tmp = TyBits; 884173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 8859a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman // vector ashr X, <C, C, C, C> -> adds C sign bits 8869a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman if (ConstantVector *C = dyn_cast<ConstantVector>(U->getOperand(1))) { 8879a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman if (ConstantInt *CI = dyn_cast_or_null<ConstantInt>(C->getSplatValue())) { 8889a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman Tmp += CI->getZExtValue(); 8899a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman if (Tmp > TyBits) Tmp = TyBits; 8909a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman } 8919a3dc552022e0e034ef34da889f6ceb9de260c96Nate Begeman } 892173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return Tmp; 893173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Shl: 894173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *C = dyn_cast<ConstantInt>(U->getOperand(1))) { 895173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // shl destroys sign bits. 896173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 897173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (C->getZExtValue() >= TyBits || // Bad shift. 898173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner C->getZExtValue() >= Tmp) break; // Shifted all sign bits out. 899173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return Tmp - C->getZExtValue(); 900173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 901173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 902173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::And: 903173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Or: 904173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Xor: // NOT is handled here. 905173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Logical binary ops preserve the number of sign bits at the worst. 906173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 907173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp != 1) { 908173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); 909173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner FirstAnswer = std::min(Tmp, Tmp2); 910173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // We computed what we know about the sign bits as our first 911173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // answer. Now proceed to the generic code that uses 912173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // ComputeMaskedBits, and pick whichever answer is better. 913173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 914173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 915173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 916173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Select: 917173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); 918173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp == 1) return 1; // Early out. 919173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp2 = ComputeNumSignBits(U->getOperand(2), TD, Depth+1); 920173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return std::min(Tmp, Tmp2); 921173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 922173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Add: 923173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Add can have at most one carry bit. Thus we know that the output 924173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // is, at worst, one more bit than the inputs. 925173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 926173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp == 1) return 1; // Early out. 927173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 928173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Special case decrementing a value (ADD X, -1): 9290001e56f15215ae4bc5fffb82eec5c4828b888f0Dan Gohman if (ConstantInt *CRHS = dyn_cast<ConstantInt>(U->getOperand(1))) 930173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (CRHS->isAllOnesValue()) { 931173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0); 932173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask = APInt::getAllOnesValue(TyBits); 933173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(U->getOperand(0), Mask, KnownZero, KnownOne, TD, 934173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 935173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 936173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If the input is known to be 0 or 1, the output is 0/-1, which is all 937173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // sign bits set. 938173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if ((KnownZero | APInt(TyBits, 1)) == Mask) 939173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return TyBits; 940173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 941173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If we are subtracting one from a positive number, there is no carry 942173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // out of the result. 943173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero.isNegative()) 944173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return Tmp; 945173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 946173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 947173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); 948173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp2 == 1) return 1; 9498d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner return std::min(Tmp, Tmp2)-1; 950173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 951173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Sub: 952173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); 953173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp2 == 1) return 1; 954173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 955173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Handle NEG. 956173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *CLHS = dyn_cast<ConstantInt>(U->getOperand(0))) 957173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (CLHS->isNullValue()) { 958173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0); 959173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask = APInt::getAllOnesValue(TyBits); 960173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(U->getOperand(1), Mask, KnownZero, KnownOne, 961173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TD, Depth+1); 962173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If the input is known to be 0 or 1, the output is 0/-1, which is all 963173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // sign bits set. 964173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if ((KnownZero | APInt(TyBits, 1)) == Mask) 965173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return TyBits; 966173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 967173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If the input is known to be positive (the sign bit is known clear), 968173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // the output of the NEG has the same number of sign bits as the input. 969173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero.isNegative()) 970173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return Tmp2; 971173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 972173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Otherwise, we treat this like a SUB. 973173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 974173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 975173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Sub can have at most one carry bit. Thus we know that the output 976173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // is, at worst, one more bit than the inputs. 977173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 978173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp == 1) return 1; // Early out. 9798d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner return std::min(Tmp, Tmp2)-1; 9808d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner 9818d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner case Instruction::PHI: { 9828d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner PHINode *PN = cast<PHINode>(U); 9838d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner // Don't analyze large in-degree PHIs. 9848d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner if (PN->getNumIncomingValues() > 4) break; 9858d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner 9868d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner // Take the minimum of all incoming values. This can't infinitely loop 9878d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner // because of our depth threshold. 9888d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner Tmp = ComputeNumSignBits(PN->getIncomingValue(0), TD, Depth+1); 9898d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) { 9908d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner if (Tmp == 1) return Tmp; 9918d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner Tmp = std::min(Tmp, 9920af20d847ac89f797d613a8a4fc3e7127ccb0b36Evan Cheng ComputeNumSignBits(PN->getIncomingValue(i), TD, Depth+1)); 9938d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner } 9948d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner return Tmp; 9958d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner } 9968d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner 997173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Trunc: 998173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // FIXME: it's tricky to do anything useful for this, but it is an important 999173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // case for targets like X86. 1000173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 1001173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 1002173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 1003173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Finally, if we can prove that the top bits of the result are 0's or 1's, 1004173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // use this information. 1005173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0); 1006173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask = APInt::getAllOnesValue(TyBits); 1007173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth); 1008173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 1009173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero.isNegative()) { // sign bit is 0 1010173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask = KnownZero; 1011173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } else if (KnownOne.isNegative()) { // sign bit is 1; 1012173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask = KnownOne; 1013173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } else { 1014173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Nothing known. 1015173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return FirstAnswer; 1016173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 1017173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 1018173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Okay, we know that the sign bit in Mask is set. Use CLZ to determine 1019173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // the number of identical bits in the top of the input value. 1020173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask = ~Mask; 1021173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask <<= Mask.getBitWidth()-TyBits; 1022173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Return # leading zeros. We use 'min' here in case Val was zero before 1023173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // shifting. We don't want to return '64' as for an i32 "0". 1024173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return std::max(FirstAnswer, std::min(TyBits, Mask.countLeadingZeros())); 1025173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner} 1026833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 10272b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez/// ComputeMultiple - This function computes the integer multiple of Base that 10282b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez/// equals V. If successful, it returns true and returns the multiple in 10293dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman/// Multiple. If unsuccessful, it returns false. It looks 10302b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez/// through SExt instructions only if LookThroughSExt is true. 10312b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandezbool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, 10323dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman bool LookThroughSExt, unsigned Depth) { 10332b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez const unsigned MaxDepth = 6; 10342b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10353dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman assert(V && "No Value?"); 10362b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez assert(Depth <= MaxDepth && "Limit Search Depth"); 1037b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands assert(V->getType()->isIntegerTy() && "Not integer or pointer type!"); 10382b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10392b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez const Type *T = V->getType(); 10402b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10413dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman ConstantInt *CI = dyn_cast<ConstantInt>(V); 10422b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10432b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Base == 0) 10442b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return false; 10452b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10462b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Base == 1) { 10472b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = V; 10482b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 10492b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 10502b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10512b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez ConstantExpr *CO = dyn_cast<ConstantExpr>(V); 10522b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Constant *BaseVal = ConstantInt::get(T, Base); 10532b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (CO && CO == BaseVal) { 10542b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // Multiple is 1. 10552b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = ConstantInt::get(T, 1); 10562b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 10572b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 10582b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10592b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (CI && CI->getZExtValue() % Base == 0) { 10602b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = ConstantInt::get(T, CI->getZExtValue() / Base); 10612b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 10622b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 10632b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10642b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Depth == MaxDepth) return false; // Limit search depth. 10652b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10662b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Operator *I = dyn_cast<Operator>(V); 10672b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (!I) return false; 10682b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10692b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez switch (I->getOpcode()) { 10702b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez default: break; 107111fe72661dac17efa1564ef6fc212acae4f0c07eChris Lattner case Instruction::SExt: 10722b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (!LookThroughSExt) return false; 10732b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // otherwise fall through to ZExt 107411fe72661dac17efa1564ef6fc212acae4f0c07eChris Lattner case Instruction::ZExt: 10753dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman return ComputeMultiple(I->getOperand(0), Base, Multiple, 10763dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman LookThroughSExt, Depth+1); 10772b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez case Instruction::Shl: 10782b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez case Instruction::Mul: { 10792b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Value *Op0 = I->getOperand(0); 10802b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Value *Op1 = I->getOperand(1); 10812b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10822b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (I->getOpcode() == Instruction::Shl) { 10832b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1); 10842b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (!Op1CI) return false; 10852b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // Turn Op0 << Op1 into Op0 * 2^Op1 10862b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez APInt Op1Int = Op1CI->getValue(); 10872b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez uint64_t BitToSet = Op1Int.getLimitedValue(Op1Int.getBitWidth() - 1); 1088a99793c5ea24dd3839f4925b89b1f6acfcb24604Jay Foad APInt API(Op1Int.getBitWidth(), 0); 10897a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad API.setBit(BitToSet); 1090a99793c5ea24dd3839f4925b89b1f6acfcb24604Jay Foad Op1 = ConstantInt::get(V->getContext(), API); 10912b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 10922b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 10932b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Value *Mul0 = NULL; 1094e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (ComputeMultiple(Op0, Base, Mul0, LookThroughSExt, Depth+1)) { 1095e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Constant *Op1C = dyn_cast<Constant>(Op1)) 1096e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Constant *MulC = dyn_cast<Constant>(Mul0)) { 1097e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Op1C->getType()->getPrimitiveSizeInBits() < 1098e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC->getType()->getPrimitiveSizeInBits()) 1099e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Op1C = ConstantExpr::getZExt(Op1C, MulC->getType()); 1100e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Op1C->getType()->getPrimitiveSizeInBits() > 1101e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC->getType()->getPrimitiveSizeInBits()) 1102e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC = ConstantExpr::getZExt(MulC, Op1C->getType()); 1103e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner 1104e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner // V == Base * (Mul0 * Op1), so return (Mul0 * Op1) 1105e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Multiple = ConstantExpr::getMul(MulC, Op1C); 1106e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner return true; 1107e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner } 11082b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 11092b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (ConstantInt *Mul0CI = dyn_cast<ConstantInt>(Mul0)) 11102b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Mul0CI->getValue() == 1) { 11112b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // V == Base * Op1, so return Op1 11122b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = Op1; 11132b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 11142b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11152b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11162b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 1117e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Value *Mul1 = NULL; 1118e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (ComputeMultiple(Op1, Base, Mul1, LookThroughSExt, Depth+1)) { 1119e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Constant *Op0C = dyn_cast<Constant>(Op0)) 1120e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Constant *MulC = dyn_cast<Constant>(Mul1)) { 1121e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Op0C->getType()->getPrimitiveSizeInBits() < 1122e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC->getType()->getPrimitiveSizeInBits()) 1123e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Op0C = ConstantExpr::getZExt(Op0C, MulC->getType()); 1124e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Op0C->getType()->getPrimitiveSizeInBits() > 1125e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC->getType()->getPrimitiveSizeInBits()) 1126e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC = ConstantExpr::getZExt(MulC, Op0C->getType()); 1127e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner 1128e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner // V == Base * (Mul1 * Op0), so return (Mul1 * Op0) 1129e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Multiple = ConstantExpr::getMul(MulC, Op0C); 1130e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner return true; 1131e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner } 11322b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 11332b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (ConstantInt *Mul1CI = dyn_cast<ConstantInt>(Mul1)) 11342b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Mul1CI->getValue() == 1) { 11352b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // V == Base * Op0, so return Op0 11362b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = Op0; 11372b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 11382b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11392b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11402b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11412b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 11422b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 11432b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // We could not determine if V is a multiple of Base. 11442b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return false; 11452b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez} 11462b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 1147833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// CannotBeNegativeZero - Return true if we can prove that the specified FP 1148833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// value is never equal to -0.0. 1149833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// 1150833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// NOTE: this function will need to be revisited when we support non-default 1151833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// rounding modes! 1152833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// 1153833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattnerbool llvm::CannotBeNegativeZero(const Value *V, unsigned Depth) { 1154833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (const ConstantFP *CFP = dyn_cast<ConstantFP>(V)) 1155833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return !CFP->getValueAPF().isNegZero(); 1156833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1157833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (Depth == 6) 1158833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return 1; // Limit search depth. 1159833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1160ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman const Operator *I = dyn_cast<Operator>(V); 1161833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (I == 0) return false; 1162833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1163833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner // (add x, 0.0) is guaranteed to return +0.0, not -0.0. 1164ae3a0be92e33bc716722aa600983fc1535acb122Dan Gohman if (I->getOpcode() == Instruction::FAdd && 1165833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner isa<ConstantFP>(I->getOperand(1)) && 1166833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner cast<ConstantFP>(I->getOperand(1))->isNullValue()) 1167833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return true; 1168833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1169833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner // sitofp and uitofp turn into +0.0 for zero. 1170833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (isa<SIToFPInst>(I) || isa<UIToFPInst>(I)) 1171833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return true; 1172833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1173833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) 1174833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner // sqrt(-0.0) = -0.0, no other negative results are possible. 1175833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (II->getIntrinsicID() == Intrinsic::sqrt) 117671339c965ca6268b9bff91213364783c3d06f666Gabor Greif return CannotBeNegativeZero(II->getArgOperand(0), Depth+1); 1177833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1178833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (const CallInst *CI = dyn_cast<CallInst>(I)) 1179833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (const Function *F = CI->getCalledFunction()) { 1180833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (F->isDeclaration()) { 1181f0443c1eb44d737d9bd78962932fc80f74c6113cDaniel Dunbar // abs(x) != -0.0 1182f0443c1eb44d737d9bd78962932fc80f74c6113cDaniel Dunbar if (F->getName() == "abs") return true; 11839d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen // fabs[lf](x) != -0.0 11849d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen if (F->getName() == "fabs") return true; 11859d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen if (F->getName() == "fabsf") return true; 11869d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen if (F->getName() == "fabsl") return true; 11879d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen if (F->getName() == "sqrt" || F->getName() == "sqrtf" || 11889d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen F->getName() == "sqrtl") 118971339c965ca6268b9bff91213364783c3d06f666Gabor Greif return CannotBeNegativeZero(CI->getArgOperand(0), Depth+1); 1190833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner } 1191833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner } 1192833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1193833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return false; 1194833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner} 1195833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 1196bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner/// isBytewiseValue - If the specified value can be set by repeating the same 1197bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner/// byte in memory, return the i8 value that it is represented with. This is 1198bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner/// true for all i8 values obviously, but is also true for i32 0, i32 -1, 1199bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner/// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated 1200bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner/// byte store (e.g. i16 0x1234), return null. 1201bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris LattnerValue *llvm::isBytewiseValue(Value *V) { 1202bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // All byte-wide stores are splatable, even of arbitrary variables. 1203bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (V->getType()->isIntegerTy(8)) return V; 120441bfbb0a8776674c486682cbf2aa80f15abfef68Chris Lattner 120541bfbb0a8776674c486682cbf2aa80f15abfef68Chris Lattner // Handle 'null' ConstantArrayZero etc. 120641bfbb0a8776674c486682cbf2aa80f15abfef68Chris Lattner if (Constant *C = dyn_cast<Constant>(V)) 120741bfbb0a8776674c486682cbf2aa80f15abfef68Chris Lattner if (C->isNullValue()) 120841bfbb0a8776674c486682cbf2aa80f15abfef68Chris Lattner return Constant::getNullValue(Type::getInt8Ty(V->getContext())); 1209bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1210bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // Constant float and double values can be handled as integer values if the 1211bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // corresponding integer value is "byteable". An important case is 0.0. 1212bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) { 1213bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (CFP->getType()->isFloatTy()) 1214bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner V = ConstantExpr::getBitCast(CFP, Type::getInt32Ty(V->getContext())); 1215bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (CFP->getType()->isDoubleTy()) 1216bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner V = ConstantExpr::getBitCast(CFP, Type::getInt64Ty(V->getContext())); 1217bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // Don't handle long double formats, which have strange constraints. 1218bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner } 1219bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1220bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // We can handle constant integers that are power of two in size and a 1221bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // multiple of 8 bits. 1222bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 1223bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner unsigned Width = CI->getBitWidth(); 1224bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (isPowerOf2_32(Width) && Width > 8) { 1225bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // We can handle this value if the recursive binary decomposition is the 1226bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // same at all levels. 1227bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner APInt Val = CI->getValue(); 1228bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner APInt Val2; 1229bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner while (Val.getBitWidth() != 8) { 1230bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner unsigned NextWidth = Val.getBitWidth()/2; 1231bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner Val2 = Val.lshr(NextWidth); 1232bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner Val2 = Val2.trunc(Val.getBitWidth()/2); 1233bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner Val = Val.trunc(Val.getBitWidth()/2); 1234bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1235bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // If the top/bottom halves aren't the same, reject it. 1236bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (Val != Val2) 1237bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return 0; 1238bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner } 1239bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return ConstantInt::get(V->getContext(), Val); 1240bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner } 1241bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner } 1242bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1243bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // A ConstantArray is splatable if all its members are equal and also 1244bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // splatable. 1245bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (ConstantArray *CA = dyn_cast<ConstantArray>(V)) { 1246bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (CA->getNumOperands() == 0) 1247bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return 0; 1248bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1249bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner Value *Val = isBytewiseValue(CA->getOperand(0)); 1250bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (!Val) 1251bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return 0; 1252bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1253bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner for (unsigned I = 1, E = CA->getNumOperands(); I != E; ++I) 1254bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner if (CA->getOperand(I-1) != CA->getOperand(I)) 1255bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return 0; 1256bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1257bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return Val; 1258bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner } 1259bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1260bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // Conceptually, we could handle things like: 1261bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // %a = zext i8 %X to i16 1262bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // %b = shl i16 %a, 8 1263bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // %c = or i16 %a, %b 1264bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // but until there is an example that actually needs this, it doesn't seem 1265bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner // worth worrying about. 1266bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner return 0; 1267bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner} 1268bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1269bb89710dddf967199dfc56e8bf5d28b0003f2ee6Chris Lattner 1270b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// This is the recursive version of BuildSubAggregate. It takes a few different 1271b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// arguments. Idxs is the index within the nested struct From that we are 1272b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// looking at now (which is of type IndexedType). IdxSkip is the number of 1273b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// indices from Idxs that should be left out when inserting into the resulting 1274b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// struct. To is the result struct built so far, new insertvalue instructions 1275b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// build on that. 12767db949df789383acce98ef072f08794fdd5bd04eDan Gohmanstatic Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType, 12777db949df789383acce98ef072f08794fdd5bd04eDan Gohman SmallVector<unsigned, 10> &Idxs, 12787db949df789383acce98ef072f08794fdd5bd04eDan Gohman unsigned IdxSkip, 12797db949df789383acce98ef072f08794fdd5bd04eDan Gohman Instruction *InsertBefore) { 1280b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman const llvm::StructType *STy = llvm::dyn_cast<llvm::StructType>(IndexedType); 1281b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (STy) { 12820a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Save the original To argument so we can modify it 12830a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman Value *OrigTo = To; 1284b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // General case, the type indexed by Idxs is a struct 1285b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { 1286b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Process each struct element recursively 1287b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman Idxs.push_back(i); 12880a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman Value *PrevTo = To; 1289710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip, 1290ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky InsertBefore); 1291b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman Idxs.pop_back(); 12920a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman if (!To) { 12930a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Couldn't find any inserted value for this index? Cleanup 12940a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman while (PrevTo != OrigTo) { 12950a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman InsertValueInst* Del = cast<InsertValueInst>(PrevTo); 12960a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman PrevTo = Del->getAggregateOperand(); 12970a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman Del->eraseFromParent(); 12980a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman } 12990a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Stop processing elements 13000a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman break; 13010a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman } 1302b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } 13030a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // If we succesfully found a value for each of our subaggregates 13040a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman if (To) 13050a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman return To; 1306b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } 13070a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Base case, the type indexed by SourceIdxs is not a struct, or not all of 13080a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // the struct's elements had a value that was inserted directly. In the latter 13090a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // case, perhaps we can't determine each of the subelements individually, but 13100a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // we might be able to find the complete struct somewhere. 13110a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman 13120a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Find the value that is at that particular spot 1313ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky Value *V = FindInsertedValue(From, Idxs.begin(), Idxs.end()); 13140a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman 13150a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman if (!V) 13160a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman return NULL; 13170a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman 13180a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Insert the value in the new (sub) aggregrate 13190a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman return llvm::InsertValueInst::Create(To, V, Idxs.begin() + IdxSkip, 13200a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman Idxs.end(), "tmp", InsertBefore); 1321b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman} 1322b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1323b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// This helper takes a nested struct and extracts a part of it (which is again a 1324b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// struct) into a new value. For example, given the struct: 1325b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// { a, { b, { c, d }, e } } 1326b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// and the indices "1, 1" this returns 1327b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// { c, d }. 1328b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// 13290a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// It does this by inserting an insertvalue for each element in the resulting 13300a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// struct, as opposed to just inserting a single struct. This will only work if 13310a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// each of the elements of the substruct are known (ie, inserted into From by an 13320a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// insertvalue instruction somewhere). 1333b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// 13340a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// All inserted insertvalue instructions are inserted before InsertBefore 13357db949df789383acce98ef072f08794fdd5bd04eDan Gohmanstatic Value *BuildSubAggregate(Value *From, const unsigned *idx_begin, 1336ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky const unsigned *idx_end, 13377db949df789383acce98ef072f08794fdd5bd04eDan Gohman Instruction *InsertBefore) { 1338977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman assert(InsertBefore && "Must have someplace to insert!"); 1339710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman const Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(), 1340710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman idx_begin, 1341710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman idx_end); 13429e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson Value *To = UndefValue::get(IndexedType); 1343b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman SmallVector<unsigned, 10> Idxs(idx_begin, idx_end); 1344b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman unsigned IdxSkip = Idxs.size(); 1345b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1346ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore); 1347b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman} 1348b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1349710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman/// FindInsertedValue - Given an aggregrate and an sequence of indices, see if 1350710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman/// the scalar value indexed is already around as a register, for example if it 1351710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman/// were inserted directly into the aggregrate. 13520a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman/// 13530a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman/// If InsertBefore is not null, this function will duplicate (modified) 13540a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman/// insertvalues when a part of a nested struct is extracted. 1355b23d5adbc8230167e711070b9298985de4580f30Matthijs KooijmanValue *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin, 1356ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky const unsigned *idx_end, Instruction *InsertBefore) { 1357b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Nothing to index? Just return V then (this is useful at the end of our 1358b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // recursion) 1359b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (idx_begin == idx_end) 1360b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman return V; 1361b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // We have indices, so V should have an indexable type 13621df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands assert((V->getType()->isStructTy() || V->getType()->isArrayTy()) 1363b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman && "Not looking at a struct or array?"); 1364b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman assert(ExtractValueInst::getIndexedType(V->getType(), idx_begin, idx_end) 1365b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman && "Invalid indices for type?"); 1366b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman const CompositeType *PTy = cast<CompositeType>(V->getType()); 136776f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson 1368b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (isa<UndefValue>(V)) 13699e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson return UndefValue::get(ExtractValueInst::getIndexedType(PTy, 1370b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman idx_begin, 1371b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman idx_end)); 1372b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman else if (isa<ConstantAggregateZero>(V)) 1373a7235ea7245028a0723e8ab7fd011386b3900777Owen Anderson return Constant::getNullValue(ExtractValueInst::getIndexedType(PTy, 137476f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson idx_begin, 137576f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson idx_end)); 1376b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman else if (Constant *C = dyn_cast<Constant>(V)) { 1377b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (isa<ConstantArray>(C) || isa<ConstantStruct>(C)) 1378b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Recursively process this constant 137976f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson return FindInsertedValue(C->getOperand(*idx_begin), idx_begin + 1, 1380ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky idx_end, InsertBefore); 1381b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } else if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) { 1382b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Loop the indices for the insertvalue instruction in parallel with the 1383b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // requested indices 1384b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman const unsigned *req_idx = idx_begin; 1385710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman for (const unsigned *i = I->idx_begin(), *e = I->idx_end(); 1386710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman i != e; ++i, ++req_idx) { 13879954c76f2c89ab3c70bfe8222534621a86f9085aDuncan Sands if (req_idx == idx_end) { 1388977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman if (InsertBefore) 13890a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // The requested index identifies a part of a nested aggregate. Handle 13900a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // this specially. For example, 13910a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %A = insertvalue { i32, {i32, i32 } } undef, i32 10, 1, 0 13920a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %B = insertvalue { i32, {i32, i32 } } %A, i32 11, 1, 1 13930a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %C = extractvalue {i32, { i32, i32 } } %B, 1 13940a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // This can be changed into 13950a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %A = insertvalue {i32, i32 } undef, i32 10, 0 13960a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %C = insertvalue {i32, i32 } %A, i32 11, 1 13970a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // which allows the unused 0,0 element from the nested struct to be 13980a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // removed. 1399ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky return BuildSubAggregate(V, idx_begin, req_idx, InsertBefore); 1400977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman else 1401977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman // We can't handle this without inserting insertvalues 1402977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman return 0; 14039954c76f2c89ab3c70bfe8222534621a86f9085aDuncan Sands } 1404b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1405b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // This insert value inserts something else than what we are looking for. 1406b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // See if the (aggregrate) value inserted into has the value we are 1407b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // looking for, then. 1408b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (*req_idx != *i) 1409710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman return FindInsertedValue(I->getAggregateOperand(), idx_begin, idx_end, 1410ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky InsertBefore); 1411b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } 1412b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // If we end up here, the indices of the insertvalue match with those 1413b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // requested (though possibly only partially). Now we recursively look at 1414b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // the inserted value, passing any remaining indices. 1415710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman return FindInsertedValue(I->getInsertedValueOperand(), req_idx, idx_end, 1416ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky InsertBefore); 1417b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } else if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) { 1418b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // If we're extracting a value from an aggregrate that was extracted from 1419b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // something else, we can extract from that something else directly instead. 1420b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // However, we will need to chain I's indices with the requested indices. 1421b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1422b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Calculate the number of indices required 1423b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman unsigned size = I->getNumIndices() + (idx_end - idx_begin); 1424b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Allocate some space to put the new indices in 14253faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman SmallVector<unsigned, 5> Idxs; 14263faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman Idxs.reserve(size); 1427b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Add indices from the extract value instruction 1428710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman for (const unsigned *i = I->idx_begin(), *e = I->idx_end(); 14293faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman i != e; ++i) 14303faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman Idxs.push_back(*i); 1431b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1432b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Add requested indices 14333faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman for (const unsigned *i = idx_begin, *e = idx_end; i != e; ++i) 14343faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman Idxs.push_back(*i); 1435b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 14363faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman assert(Idxs.size() == size 1437710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman && "Number of indices added not correct?"); 1438b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 14393faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman return FindInsertedValue(I->getAggregateOperand(), Idxs.begin(), Idxs.end(), 1440ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky InsertBefore); 1441b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } 1442b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Otherwise, we don't know (such as, extracting from a function return value 1443b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // or load instruction) 1444b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman return 0; 1445b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman} 14460ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 1447ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner/// GetPointerBaseWithConstantOffset - Analyze the specified pointer to see if 1448ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner/// it can be expressed as a base pointer plus a constant offset. Return the 1449ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner/// base and offset to the caller. 1450ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris LattnerValue *llvm::GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset, 1451ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner const TargetData &TD) { 1452ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner Operator *PtrOp = dyn_cast<Operator>(Ptr); 1453ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (PtrOp == 0) return Ptr; 1454ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1455ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // Just look through bitcasts. 1456ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (PtrOp->getOpcode() == Instruction::BitCast) 1457ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner return GetPointerBaseWithConstantOffset(PtrOp->getOperand(0), Offset, TD); 1458ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1459ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // If this is a GEP with constant indices, we can look through it. 1460ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner GEPOperator *GEP = dyn_cast<GEPOperator>(PtrOp); 1461ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (GEP == 0 || !GEP->hasAllConstantIndices()) return Ptr; 1462ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1463ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner gep_type_iterator GTI = gep_type_begin(GEP); 1464ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner for (User::op_iterator I = GEP->idx_begin(), E = GEP->idx_end(); I != E; 1465ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner ++I, ++GTI) { 1466ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner ConstantInt *OpC = cast<ConstantInt>(*I); 1467ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (OpC->isZero()) continue; 1468ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1469ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // Handle a struct and array indices which add their offset to the pointer. 1470ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (const StructType *STy = dyn_cast<StructType>(*GTI)) { 1471ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); 1472ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner } else { 1473ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); 1474ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner Offset += OpC->getSExtValue()*Size; 1475ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner } 1476ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner } 1477ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1478ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // Re-sign extend from the pointer size if needed to get overflow edge cases 1479ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // right. 1480ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner unsigned PtrSize = TD.getPointerSizeInBits(); 1481ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (PtrSize < 64) 1482ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner Offset = (Offset << (64-PtrSize)) >> (64-PtrSize); 1483ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1484ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner return GetPointerBaseWithConstantOffset(GEP->getPointerOperand(), Offset, TD); 1485ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner} 1486ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1487ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 14880ff39b3feb10477c224138156941234f5fa46f58Evan Cheng/// GetConstantStringInfo - This function computes the length of a 14890ff39b3feb10477c224138156941234f5fa46f58Evan Cheng/// null-terminated C string pointed to by V. If successful, it returns true 14900ff39b3feb10477c224138156941234f5fa46f58Evan Cheng/// and returns the string in Str. If unsuccessful, it returns false. 14910a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohmanbool llvm::GetConstantStringInfo(const Value *V, std::string &Str, 14920a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman uint64_t Offset, 14930582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling bool StopAtNul) { 14940582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling // If V is NULL then return false; 14950582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (V == NULL) return false; 14960ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 14970ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Look through bitcast instructions. 14980a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman if (const BitCastInst *BCI = dyn_cast<BitCastInst>(V)) 14990582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return GetConstantStringInfo(BCI->getOperand(0), Str, Offset, StopAtNul); 15000582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling 15010ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // If the value is not a GEP instruction nor a constant expression with a 15020ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // GEP instruction, then return false because ConstantArray can't occur 15030ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // any other way 15040a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const User *GEP = 0; 15050a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) { 15060ff39b3feb10477c224138156941234f5fa46f58Evan Cheng GEP = GEPI; 15070a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 15080ff39b3feb10477c224138156941234f5fa46f58Evan Cheng if (CE->getOpcode() == Instruction::BitCast) 15090582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return GetConstantStringInfo(CE->getOperand(0), Str, Offset, StopAtNul); 15100582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (CE->getOpcode() != Instruction::GetElementPtr) 15110582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15120ff39b3feb10477c224138156941234f5fa46f58Evan Cheng GEP = CE; 15130ff39b3feb10477c224138156941234f5fa46f58Evan Cheng } 15140ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15150ff39b3feb10477c224138156941234f5fa46f58Evan Cheng if (GEP) { 15160ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Make sure the GEP has exactly three arguments. 15170582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (GEP->getNumOperands() != 3) 15180582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15190582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling 15200ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Make sure the index-ee is a pointer to array of i8. 15210ff39b3feb10477c224138156941234f5fa46f58Evan Cheng const PointerType *PT = cast<PointerType>(GEP->getOperand(0)->getType()); 15220ff39b3feb10477c224138156941234f5fa46f58Evan Cheng const ArrayType *AT = dyn_cast<ArrayType>(PT->getElementType()); 1523b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands if (AT == 0 || !AT->getElementType()->isIntegerTy(8)) 15240582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15250ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15260ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Check to make sure that the first operand of the GEP is an integer and 15270ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // has value 0 so that we are sure we're indexing into the initializer. 15280a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const ConstantInt *FirstIdx = dyn_cast<ConstantInt>(GEP->getOperand(1)); 15290582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (FirstIdx == 0 || !FirstIdx->isZero()) 15300582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15310ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15320ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // If the second index isn't a ConstantInt, then this is a variable index 15330ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // into the array. If this occurs, we can't say anything meaningful about 15340ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // the string. 15350ff39b3feb10477c224138156941234f5fa46f58Evan Cheng uint64_t StartIdx = 0; 15360a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman if (const ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2))) 15370ff39b3feb10477c224138156941234f5fa46f58Evan Cheng StartIdx = CI->getZExtValue(); 15380582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling else 15390582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15400582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return GetConstantStringInfo(GEP->getOperand(0), Str, StartIdx+Offset, 15410ff39b3feb10477c224138156941234f5fa46f58Evan Cheng StopAtNul); 15420ff39b3feb10477c224138156941234f5fa46f58Evan Cheng } 15430ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15440ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // The GEP instruction, constant or instruction, must reference a global 15450ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // variable that is a constant and is initialized. The referenced constant 15460ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // initializer is the array that we'll use for optimization. 15470a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const GlobalVariable* GV = dyn_cast<GlobalVariable>(V); 15488255573835970e7130ba93271972172fb335f2ecDan Gohman if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer()) 15490582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15500a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const Constant *GlobalInit = GV->getInitializer(); 15510ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15520ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Handle the ConstantAggregateZero case 15530582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (isa<ConstantAggregateZero>(GlobalInit)) { 15540ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // This is a degenerate case. The initializer is constant zero so the 15550ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // length of the string must be zero. 15560582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling Str.clear(); 15570582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return true; 15580582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling } 15590ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15600ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Must be a Constant Array 15610a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit); 1562b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands if (Array == 0 || !Array->getType()->getElementType()->isIntegerTy(8)) 15630582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15640ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15650ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Get the number of elements in the array 15660ff39b3feb10477c224138156941234f5fa46f58Evan Cheng uint64_t NumElts = Array->getType()->getNumElements(); 15670ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15680582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (Offset > NumElts) 15690582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15700ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 15710ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Traverse the constant array from 'Offset' which is the place the GEP refers 15720ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // to in the array. 15730582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling Str.reserve(NumElts-Offset); 15740ff39b3feb10477c224138156941234f5fa46f58Evan Cheng for (unsigned i = Offset; i != NumElts; ++i) { 15750a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const Constant *Elt = Array->getOperand(i); 15760a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const ConstantInt *CI = dyn_cast<ConstantInt>(Elt); 15770582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (!CI) // This array isn't suitable, non-int initializer. 15780582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 15790ff39b3feb10477c224138156941234f5fa46f58Evan Cheng if (StopAtNul && CI->isZero()) 15800582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return true; // we found end of string, success! 15810582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling Str += (char)CI->getZExtValue(); 15820ff39b3feb10477c224138156941234f5fa46f58Evan Cheng } 15830582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling 15840ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // The array isn't null terminated, but maybe this is a memcpy, not a strcpy. 15850582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return true; 15860ff39b3feb10477c224138156941234f5fa46f58Evan Cheng} 158725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 158825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher// These next two are very similar to the above, but also look through PHI 158925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher// nodes. 159025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher// TODO: See if we can integrate these two together. 159125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 159225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher/// GetStringLengthH - If we can compute the length of the string pointed to by 159325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher/// the specified pointer, return 'len+1'. If we can't, return 0. 159425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopherstatic uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) { 159525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Look through noop bitcast instructions. 159625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (BitCastInst *BCI = dyn_cast<BitCastInst>(V)) 159725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return GetStringLengthH(BCI->getOperand(0), PHIs); 159825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 159925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If this is a PHI node, there are two cases: either we have already seen it 160025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // or we haven't. 160125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (PHINode *PN = dyn_cast<PHINode>(V)) { 160225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!PHIs.insert(PN)) 160325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return ~0ULL; // already in the set. 160425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 160525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If it was new, see if all the input strings are the same length. 160625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t LenSoFar = ~0ULL; 160725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 160825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs); 160925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len == 0) return 0; // Unknown length -> unknown. 161025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 161125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len == ~0ULL) continue; 161225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 161325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len != LenSoFar && LenSoFar != ~0ULL) 161425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; // Disagree -> unknown. 161525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher LenSoFar = Len; 161625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 161725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 161825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Success, all agree. 161925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return LenSoFar; 162025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 162125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 162225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y) 162325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (SelectInst *SI = dyn_cast<SelectInst>(V)) { 162425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs); 162525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len1 == 0) return 0; 162625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs); 162725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len2 == 0) return 0; 162825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len1 == ~0ULL) return Len2; 162925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len2 == ~0ULL) return Len1; 163025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len1 != Len2) return 0; 163125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return Len1; 163225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 163325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 163425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If the value is not a GEP instruction nor a constant expression with a 163525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // GEP instruction, then return unknown. 163625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher User *GEP = 0; 163725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) { 163825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher GEP = GEPI; 163925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 164025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (CE->getOpcode() != Instruction::GetElementPtr) 164125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 164225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher GEP = CE; 164325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } else { 164425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 164525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 164625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 164725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Make sure the GEP has exactly three arguments. 164825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (GEP->getNumOperands() != 3) 164925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 165025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 165125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Check to make sure that the first operand of the GEP is an integer and 165225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // has value 0 so that we are sure we're indexing into the initializer. 165325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) { 165425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!Idx->isZero()) 165525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 165625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } else 165725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 165825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 165925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If the second index isn't a ConstantInt, then this is a variable index 166025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // into the array. If this occurs, we can't say anything meaningful about 166125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // the string. 166225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t StartIdx = 0; 166325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2))) 166425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher StartIdx = CI->getZExtValue(); 166525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher else 166625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 166725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 166825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // The GEP instruction, constant or instruction, must reference a global 166925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // variable that is a constant and is initialized. The referenced constant 167025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // initializer is the array that we'll use for optimization. 167125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)); 167225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!GV || !GV->isConstant() || !GV->hasInitializer() || 167325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher GV->mayBeOverridden()) 167425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 167525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher Constant *GlobalInit = GV->getInitializer(); 167625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 167725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Handle the ConstantAggregateZero case, which is a degenerate case. The 167825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // initializer is constant zero so the length of the string must be zero. 167925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (isa<ConstantAggregateZero>(GlobalInit)) 168025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 1; // Len = 0 offset by 1. 168125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 168225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Must be a Constant Array 168325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit); 168425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!Array || !Array->getType()->getElementType()->isIntegerTy(8)) 168525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return false; 168625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 168725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Get the number of elements in the array 168825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t NumElts = Array->getType()->getNumElements(); 168925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 169025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Traverse the constant array from StartIdx (derived above) which is 169125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // the place the GEP refers to in the array. 169225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher for (unsigned i = StartIdx; i != NumElts; ++i) { 169325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher Constant *Elt = Array->getOperand(i); 169425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher ConstantInt *CI = dyn_cast<ConstantInt>(Elt); 169525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!CI) // This array isn't suitable, non-int initializer. 169625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 169725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (CI->isZero()) 169825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return i-StartIdx+1; // We found end of string, success! 169925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 170025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 170125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; // The array isn't null terminated, conservatively return 'unknown'. 170225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher} 170325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 170425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher/// GetStringLength - If we can compute the length of the string pointed to by 170525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher/// the specified pointer, return 'len+1'. If we can't, return 0. 170625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopheruint64_t llvm::GetStringLength(Value *V) { 170725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!V->getType()->isPointerTy()) return 0; 170825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 170925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher SmallPtrSet<PHINode*, 32> PHIs; 171025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t Len = GetStringLengthH(V, PHIs); 171125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return 171225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // an empty string as a length. 171325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return Len == ~0ULL ? 1 : Len; 171425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher} 17155034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman 1716bd1801b5553c8be3960255a92738464e0010b6f6Dan GohmanValue * 1717bd1801b5553c8be3960255a92738464e0010b6f6Dan Gohmanllvm::GetUnderlyingObject(Value *V, const TargetData *TD, unsigned MaxLookup) { 17185034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman if (!V->getType()->isPointerTy()) 17195034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman return V; 17205034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) { 17215034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { 17225034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman V = GEP->getPointerOperand(); 17235034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } else if (Operator::getOpcode(V) == Instruction::BitCast) { 17245034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman V = cast<Operator>(V)->getOperand(0); 17255034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { 17265034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman if (GA->mayBeOverridden()) 17275034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman return V; 17285034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman V = GA->getAliasee(); 17295034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } else { 1730c01895c7db4c4d8883dd4c31427c42cdae356567Dan Gohman // See if InstructionSimplify knows any relevant tricks. 1731c01895c7db4c4d8883dd4c31427c42cdae356567Dan Gohman if (Instruction *I = dyn_cast<Instruction>(V)) 1732bd1801b5553c8be3960255a92738464e0010b6f6Dan Gohman // TODO: Aquire a DominatorTree and use it. 1733bd1801b5553c8be3960255a92738464e0010b6f6Dan Gohman if (Value *Simplified = SimplifyInstruction(I, TD, 0)) { 1734c01895c7db4c4d8883dd4c31427c42cdae356567Dan Gohman V = Simplified; 1735c01895c7db4c4d8883dd4c31427c42cdae356567Dan Gohman continue; 1736c01895c7db4c4d8883dd4c31427c42cdae356567Dan Gohman } 1737c01895c7db4c4d8883dd4c31427c42cdae356567Dan Gohman 17385034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman return V; 17395034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } 17405034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman assert(V->getType()->isPointerTy() && "Unexpected operand type!"); 17415034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } 17425034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman return V; 17435034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman} 1744