ValueTracking.cpp revision 5034dd318a9dfa0dc45a3ac01e58e60f2aa2498d
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" 16173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner#include "llvm/Constants.h" 17173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner#include "llvm/Instructions.h" 180ff39b3feb10477c224138156941234f5fa46f58Evan Cheng#include "llvm/GlobalVariable.h" 19307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman#include "llvm/GlobalAlias.h" 20173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner#include "llvm/IntrinsicInst.h" 2176f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson#include "llvm/LLVMContext.h" 22ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman#include "llvm/Operator.h" 230582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling#include "llvm/Target/TargetData.h" 24173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner#include "llvm/Support/GetElementPtrTypeIterator.h" 25173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner#include "llvm/Support/MathExtras.h" 2625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher#include "llvm/ADT/SmallPtrSet.h" 2732a9e7a2654c4aab2e617fbe53140492b3d38066Chris Lattner#include <cstring> 28173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattnerusing namespace llvm; 29173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 30173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// ComputeMaskedBits - Determine which of the bits specified in Mask are 31173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// known to be either zero or one and return them in the KnownZero/KnownOne 32173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// bit sets. This code only analyzes bits in Mask, in order to short-circuit 33173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// processing. 34173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// NOTE: we cannot consider 'undef' to be "IsZero" here. The problem is that 35173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// we cannot optimize based on the assumption that it is zero without changing 36173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// it to be an explicit zero. If we don't change it to zero, other code could 37173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// optimized based on the contradictory assumption that it is non-zero. 38173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// Because instcombine aggressively folds operations with undef args anyway, 39173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// this won't lose us code quality. 40cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// 41cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// This function is defined on values with integer type, values with pointer 42cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// type (but only if TD is non-null), and vectors of integers. In the case 43cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// where V is a vector, the mask, known zero, and known one values are the 44cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// same width as the vector element, and the bit is set only if it is true 45cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// for all of the elements in the vector. 46173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattnervoid llvm::ComputeMaskedBits(Value *V, const APInt &Mask, 47173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt &KnownZero, APInt &KnownOne, 48846a2f2703f6bb894098274964faf5dce0b68c4dDan Gohman const TargetData *TD, unsigned Depth) { 499004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman const unsigned MaxDepth = 6; 50173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert(V && "No Value?"); 519004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman assert(Depth <= MaxDepth && "Limit Search Depth"); 5279abedb83a4dd7d3583c7ca6df8283079acc3ba5Chris Lattner unsigned BitWidth = Mask.getBitWidth(); 531df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands assert((V->getType()->isIntOrIntVectorTy() || V->getType()->isPointerTy()) 54b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands && "Not integer or pointer type!"); 556de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman assert((!TD || 566de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman TD->getTypeSizeInBits(V->getType()->getScalarType()) == BitWidth) && 57b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands (!V->getType()->isIntOrIntVectorTy() || 586de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman V->getType()->getScalarSizeInBits() == BitWidth) && 59173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero.getBitWidth() == BitWidth && 60173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne.getBitWidth() == BitWidth && 61173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner "V, Mask, KnownOne and KnownZero should have same BitWidth"); 62173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 63173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 64173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // We know all of the bits for a constant! 65173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne = CI->getValue() & Mask; 66173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = ~KnownOne & Mask; 67173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 68173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 696de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman // Null and aggregate-zero are all-zeros. 706de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman if (isa<ConstantPointerNull>(V) || 716de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman isa<ConstantAggregateZero>(V)) { 727a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownOne.clearAllBits(); 73173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = Mask; 74173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 75173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 766de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman // Handle a constant vector by taking the intersection of the known bits of 776de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman // each element. 786de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman if (ConstantVector *CV = dyn_cast<ConstantVector>(V)) { 797a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownZero.setAllBits(); KnownOne.setAllBits(); 806de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) { 816de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman APInt KnownZero2(BitWidth, 0), KnownOne2(BitWidth, 0); 826de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman ComputeMaskedBits(CV->getOperand(i), Mask, KnownZero2, KnownOne2, 836de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman TD, Depth); 846de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman KnownZero &= KnownZero2; 856de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman KnownOne &= KnownOne2; 866de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman } 876de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman return; 886de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman } 89173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // The address of an aligned GlobalValue has trailing zeros. 90173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { 91173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned Align = GV->getAlignment(); 92004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman if (Align == 0 && TD && GV->getType()->getElementType()->isSized()) { 93004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman const Type *ObjectType = GV->getType()->getElementType(); 94004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman // If the object is defined in the current Module, we'll be giving 95004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman // it the preferred alignment. Otherwise, we have to assume that it 96004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman // may only have the minimum ABI alignment. 97004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman if (!GV->isDeclaration() && !GV->mayBeOverridden()) 98004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman Align = TD->getPrefTypeAlignment(ObjectType); 99004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman else 100004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman Align = TD->getABITypeAlignment(ObjectType); 101004072508bfc66159ca09be26f06b8b05c1bac4eDan Gohman } 102173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Align > 0) 103173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = Mask & APInt::getLowBitsSet(BitWidth, 104173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner CountTrailingZeros_32(Align)); 105173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner else 1067a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownZero.clearAllBits(); 1077a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownOne.clearAllBits(); 108173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 109173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 110307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman // A weak GlobalAlias is totally unknown. A non-weak GlobalAlias has 111307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman // the bits of its aliasee. 112307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { 113307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman if (GA->mayBeOverridden()) { 1147a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownZero.clearAllBits(); KnownOne.clearAllBits(); 115307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman } else { 116307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman ComputeMaskedBits(GA->getAliasee(), Mask, KnownZero, KnownOne, 117307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman TD, Depth+1); 118307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman } 119307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman return; 120307a7c48f15b087663b60d600d23afffb9e211e6Dan Gohman } 121173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 1227a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownZero.clearAllBits(); KnownOne.clearAllBits(); // Start out not knowing anything. 123173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 1249004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman if (Depth == MaxDepth || Mask == 0) 125173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; // Limit search depth. 126173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 127ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman Operator *I = dyn_cast<Operator>(V); 128173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!I) return; 129173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 130173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero2(KnownZero), KnownOne2(KnownOne); 131ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman switch (I->getOpcode()) { 132173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner default: break; 133173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::And: { 134173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If either the LHS or the RHS are Zero, the result is zero. 135173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, TD, Depth+1); 136173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2(Mask & ~KnownZero); 137173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD, 138173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 139173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 140173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); 141173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 142173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Output known-1 bits are only known if set in both the LHS & RHS. 143173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne &= KnownOne2; 144173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Output known-0 are known to be clear if zero in either the LHS | RHS. 145173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= KnownZero2; 146173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 147173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 148173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Or: { 149173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, TD, Depth+1); 150173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2(Mask & ~KnownOne); 151173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD, 152173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 153173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 154173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); 155173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 156173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Output known-0 bits are only known if clear in both the LHS & RHS. 157173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero &= KnownZero2; 158173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Output known-1 are known to be set if set in either the LHS | RHS. 159173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne |= KnownOne2; 160173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 161173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 162173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Xor: { 163173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, TD, Depth+1); 164173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask, 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 known if clear or set in both the LHS & RHS. 170173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2); 171173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Output known-1 are known to be set if set in only one of the LHS, RHS. 172173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2); 173173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = KnownZeroOut; 174173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 175173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 176173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Mul: { 177173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2 = APInt::getAllOnesValue(BitWidth); 178173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), Mask2, KnownZero, KnownOne, TD,Depth+1); 179173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD, 180173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 181173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 182173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); 183173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 184173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If low bits are zero in either operand, output low known-0 bits. 185173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Also compute a conserative estimate for high known-0 bits. 186173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // More trickiness is possible, but this is sufficient for the 187173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // interesting case of alignment computation. 1887a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownOne.clearAllBits(); 189173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned TrailZ = KnownZero.countTrailingOnes() + 190173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero2.countTrailingOnes(); 191173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned LeadZ = std::max(KnownZero.countLeadingOnes() + 192173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero2.countLeadingOnes(), 193173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner BitWidth) - BitWidth; 194173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 195173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TrailZ = std::min(TrailZ, BitWidth); 196173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LeadZ = std::min(LeadZ, BitWidth); 197173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getLowBitsSet(BitWidth, TrailZ) | 198173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt::getHighBitsSet(BitWidth, LeadZ); 199173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero &= Mask; 200173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 201173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 202173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::UDiv: { 203173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // For the purposes of computing leading zeros we can conservatively 204173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // treat a udiv as a logical right shift by the power of 2 known to 205173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // be less than the denominator. 206173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt AllOnes = APInt::getAllOnesValue(BitWidth); 207173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), 208173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner AllOnes, KnownZero2, KnownOne2, TD, Depth+1); 209173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned LeadZ = KnownZero2.countLeadingOnes(); 210173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 2117a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownOne2.clearAllBits(); 2127a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownZero2.clearAllBits(); 213173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), 214173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner AllOnes, KnownZero2, KnownOne2, TD, Depth+1); 215173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned RHSUnknownLeadingOnes = KnownOne2.countLeadingZeros(); 216173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (RHSUnknownLeadingOnes != BitWidth) 217173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LeadZ = std::min(BitWidth, 218173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LeadZ + BitWidth - RHSUnknownLeadingOnes - 1); 219173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 220173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getHighBitsSet(BitWidth, LeadZ) & Mask; 221173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 222173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 223173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Select: 224173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(2), Mask, KnownZero, KnownOne, TD, Depth+1); 225173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), Mask, KnownZero2, KnownOne2, TD, 226173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 227173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 228173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); 229173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 230173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Only known if known in both the LHS and RHS. 231173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne &= KnownOne2; 232173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero &= KnownZero2; 233173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 234173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::FPTrunc: 235173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::FPExt: 236173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::FPToUI: 237173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::FPToSI: 238173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::SIToFP: 239173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::UIToFP: 240173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; // Can't work with floating point. 241173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::PtrToInt: 242173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::IntToPtr: 243173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // We can't handle these if we don't know the pointer size. 244173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!TD) return; 245173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // FALL THROUGH and handle them the same as zext/trunc. 246173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::ZExt: 247173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Trunc: { 248b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner const Type *SrcTy = I->getOperand(0)->getType(); 249b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner 250b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner unsigned SrcBitWidth; 251173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Note that we handle pointer operands here because of inttoptr/ptrtoint 252173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // which fall through here. 2531df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (SrcTy->isPointerTy()) 254b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner SrcBitWidth = TD->getTypeSizeInBits(SrcTy); 255b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner else 256b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner SrcBitWidth = SrcTy->getScalarSizeInBits(); 257b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner 25840f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad APInt MaskIn = Mask.zextOrTrunc(SrcBitWidth); 25940f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownZero = KnownZero.zextOrTrunc(SrcBitWidth); 26040f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownOne = KnownOne.zextOrTrunc(SrcBitWidth); 261173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, TD, 262173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 26340f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownZero = KnownZero.zextOrTrunc(BitWidth); 26440f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownOne = KnownOne.zextOrTrunc(BitWidth); 265173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Any top bits are known to be zero. 266173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (BitWidth > SrcBitWidth) 267173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth); 268173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 269173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 270173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::BitCast: { 271173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner const Type *SrcTy = I->getOperand(0)->getType(); 2721df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if ((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && 2730dabb0b177089202dae485d085ed15bd41ef29e6Chris Lattner // TODO: For now, not handling conversions like: 2740dabb0b177089202dae485d085ed15bd41ef29e6Chris Lattner // (bitcast i64 %x to <2 x i32>) 2751df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands !I->getType()->isVectorTy()) { 276173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, TD, 277173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 278173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 279173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 280173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 281173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 282173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::SExt: { 283173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Compute the bits in the result that are not present in the input. 284b9a4ddbbcd668a94fe945f0648010c281e272889Chris Lattner unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits(); 285173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 28640f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad APInt MaskIn = Mask.trunc(SrcBitWidth); 28740f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownZero = KnownZero.trunc(SrcBitWidth); 28840f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownOne = KnownOne.trunc(SrcBitWidth); 289173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, TD, 290173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 291173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 29240f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownZero = KnownZero.zext(BitWidth); 29340f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad KnownOne = KnownOne.zext(BitWidth); 294173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 295173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If the sign bit of the input is known set or clear, then we know the 296173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // top bits of the result. 297173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero[SrcBitWidth-1]) // Input sign bit known zero 298173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth); 299173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner else if (KnownOne[SrcBitWidth-1]) // Input sign bit known set 300173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth); 301173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 302173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 303173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Shl: 304173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0 305173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { 306173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner uint64_t ShiftAmt = SA->getLimitedValue(BitWidth); 307173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2(Mask.lshr(ShiftAmt)); 308173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, TD, 309173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 310173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 311173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero <<= ShiftAmt; 312173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne <<= ShiftAmt; 313173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt); // low bits known 0 314173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 315173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 316173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 317173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::LShr: 318173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0 319173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { 320173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Compute the new bits that are at the top now. 321173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner uint64_t ShiftAmt = SA->getLimitedValue(BitWidth); 322173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 323173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Unsigned shift right. 324173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2(Mask.shl(ShiftAmt)); 325173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero,KnownOne, TD, 326173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 327ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 328173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APIntOps::lshr(KnownZero, ShiftAmt); 329173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne = APIntOps::lshr(KnownOne, ShiftAmt); 330173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // high bits known zero. 331173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= APInt::getHighBitsSet(BitWidth, ShiftAmt); 332173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 333173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 334173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 335173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::AShr: 336173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // (ashr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0 337173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { 338173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Compute the new bits that are at the top now. 339173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner uint64_t ShiftAmt = SA->getLimitedValue(BitWidth); 340173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 341173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Signed shift right. 342173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2(Mask.shl(ShiftAmt)); 343173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, TD, 344173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 345ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 346173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APIntOps::lshr(KnownZero, ShiftAmt); 347173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne = APIntOps::lshr(KnownOne, ShiftAmt); 348173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 349173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt)); 350173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero[BitWidth-ShiftAmt-1]) // New bits are known zero. 351173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= HighBits; 352173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner else if (KnownOne[BitWidth-ShiftAmt-1]) // New bits are known one. 353173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownOne |= HighBits; 354173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 355173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 356173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 357173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Sub: { 358173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *CLHS = dyn_cast<ConstantInt>(I->getOperand(0))) { 359173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // We know that the top bits of C-X are clear if X contains less bits 360173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // than C (i.e. no wrap-around can happen). For example, 20-X is 361173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // positive if we can prove that X is >= 0 and < 16. 362173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!CLHS->getValue().isNegative()) { 363173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned NLZ = (CLHS->getValue()+1).countLeadingZeros(); 364173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // NLZ can't be BitWidth with no sign bit 365173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt MaskV = APInt::getHighBitsSet(BitWidth, NLZ+1); 366173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), MaskV, KnownZero2, KnownOne2, 367173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TD, Depth+1); 368173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 369173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If all of the MaskV bits are known to be zero, then we know the 370173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // output top bits are zero, because we now know that the output is 371173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // from [0-C]. 372173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if ((KnownZero2 & MaskV) == MaskV) { 373173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned NLZ2 = CLHS->getValue().countLeadingZeros(); 374173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Top bits known zero. 375173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getHighBitsSet(BitWidth, NLZ2) & Mask; 376173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 377173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 378173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 379173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 380173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // fall through 381173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Add: { 382ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky // If one of the operands has trailing zeros, then the bits that the 3833925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // other operand has in those bit positions will be preserved in the 3843925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // result. For an add, this works with either operand. For a subtract, 3853925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // this only works if the known zeros are in the right operand. 3863925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0); 3873925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman APInt Mask2 = APInt::getLowBitsSet(BitWidth, 3883925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman BitWidth - Mask.countLeadingZeros()); 3893925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman ComputeMaskedBits(I->getOperand(0), Mask2, LHSKnownZero, LHSKnownOne, TD, 390173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 3913925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman assert((LHSKnownZero & LHSKnownOne) == 0 && 3923925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman "Bits known to be one AND zero?"); 3933925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman unsigned LHSKnownZeroOut = LHSKnownZero.countTrailingOnes(); 394173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 395173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), Mask2, KnownZero2, KnownOne2, TD, 396173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 397173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); 3983925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman unsigned RHSKnownZeroOut = KnownZero2.countTrailingOnes(); 399173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 4003925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // Determine which operand has more trailing zeros, and use that 4013925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // many bits from the other operand. 4023925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman if (LHSKnownZeroOut > RHSKnownZeroOut) { 403ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman if (I->getOpcode() == Instruction::Add) { 4043925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman APInt Mask = APInt::getLowBitsSet(BitWidth, LHSKnownZeroOut); 4053925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman KnownZero |= KnownZero2 & Mask; 4063925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman KnownOne |= KnownOne2 & Mask; 4073925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman } else { 4083925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // If the known zeros are in the left operand for a subtract, 4093925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman // fall back to the minimum known zeros in both operands. 4103925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman KnownZero |= APInt::getLowBitsSet(BitWidth, 4113925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman std::min(LHSKnownZeroOut, 4123925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman RHSKnownZeroOut)); 4133925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman } 4143925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman } else if (RHSKnownZeroOut >= LHSKnownZeroOut) { 4153925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman APInt Mask = APInt::getLowBitsSet(BitWidth, RHSKnownZeroOut); 4163925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman KnownZero |= LHSKnownZero & Mask; 4173925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman KnownOne |= LHSKnownOne & Mask; 4183925043af0ecf1f0a6158c5007c1186797a252cbDan Gohman } 419173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return; 420173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 421173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::SRem: 422173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { 423cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands APInt RA = Rem->getValue().abs(); 424cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands if (RA.isPowerOf2()) { 425cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands APInt LowBits = RA - 1; 426173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2 = LowBits | APInt::getSignBit(BitWidth); 427173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD, 428173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 429173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 430cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // The low bits of the first operand are unchanged by the srem. 431cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownZero = KnownZero2 & LowBits; 432cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownOne = KnownOne2 & LowBits; 433cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands 434cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // If the first operand is non-negative or has all low bits zero, then 435cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // the upper bits are all zero. 436173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero2[BitWidth-1] || ((KnownZero2 & LowBits) == LowBits)) 437cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownZero |= ~LowBits; 438173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 439cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // If the first operand is negative and not all low bits are zero, then 440cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands // the upper bits are all one. 441cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands if (KnownOne2[BitWidth-1] && ((KnownOne2 & LowBits) != 0)) 442cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownOne |= ~LowBits; 443cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands 444cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownZero &= Mask; 445cfd54181a44db5ac75cd4a7d0a3c6a199ab01c29Duncan Sands KnownOne &= Mask; 446173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 447ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 448173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 449173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 450173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 451173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::URem: { 452173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { 453173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt RA = Rem->getValue(); 454173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (RA.isPowerOf2()) { 455173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt LowBits = (RA - 1); 456173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2 = LowBits & Mask; 457173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero |= ~LowBits & Mask; 458173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, TD, 459173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 460ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 461173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 462173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 463173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 464173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 465173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Since the result is less than or equal to either operand, any leading 466173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // zero bits in either operand must also exist in the result. 467173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt AllOnes = APInt::getAllOnesValue(BitWidth); 468173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), AllOnes, KnownZero, KnownOne, 469173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TD, Depth+1); 470173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(1), AllOnes, KnownZero2, KnownOne2, 471173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TD, Depth+1); 472173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 47379abedb83a4dd7d3583c7ca6df8283079acc3ba5Chris Lattner unsigned Leaders = std::max(KnownZero.countLeadingOnes(), 474173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero2.countLeadingOnes()); 4757a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad KnownOne.clearAllBits(); 476173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getHighBitsSet(BitWidth, Leaders) & Mask; 477173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 478173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 479173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 480a276c603b82a11b0bf0b59f0517a69e4b63adeabVictor Hernandez case Instruction::Alloca: { 4817b929dad59785f62a66f7c58615082f98441e95eVictor Hernandez AllocaInst *AI = cast<AllocaInst>(V); 482173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned Align = AI->getAlignment(); 483a276c603b82a11b0bf0b59f0517a69e4b63adeabVictor Hernandez if (Align == 0 && TD) 484a276c603b82a11b0bf0b59f0517a69e4b63adeabVictor Hernandez Align = TD->getABITypeAlignment(AI->getType()->getElementType()); 485173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 486173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Align > 0) 487173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = Mask & APInt::getLowBitsSet(BitWidth, 488173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner CountTrailingZeros_32(Align)); 489173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 490173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 491173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::GetElementPtr: { 492173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Analyze all of the subscripts of this getelementptr instruction 493173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // to determine if we can prove known low zero bits. 494173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt LocalMask = APInt::getAllOnesValue(BitWidth); 495173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt LocalKnownZero(BitWidth, 0), LocalKnownOne(BitWidth, 0); 496173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(I->getOperand(0), LocalMask, 497173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LocalKnownZero, LocalKnownOne, TD, Depth+1); 498173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned TrailZ = LocalKnownZero.countTrailingOnes(); 499173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 500173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner gep_type_iterator GTI = gep_type_begin(I); 501173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i, ++GTI) { 502173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *Index = I->getOperand(i); 503173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (const StructType *STy = dyn_cast<StructType>(*GTI)) { 504173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Handle struct member offset arithmetic. 505173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!TD) return; 506173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner const StructLayout *SL = TD->getStructLayout(STy); 507173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned Idx = cast<ConstantInt>(Index)->getZExtValue(); 508173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner uint64_t Offset = SL->getElementOffset(Idx); 509173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TrailZ = std::min(TrailZ, 510173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner CountTrailingZeros_64(Offset)); 511173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } else { 512173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Handle array index arithmetic. 513173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner const Type *IndexedTy = GTI.getIndexedType(); 514173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!IndexedTy->isSized()) return; 5156de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman unsigned GEPOpiBits = Index->getType()->getScalarSizeInBits(); 516777d2306b36816a53bc1ae1244c0dc7d998ae691Duncan Sands uint64_t TypeSize = TD ? TD->getTypeAllocSize(IndexedTy) : 1; 517173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LocalMask = APInt::getAllOnesValue(GEPOpiBits); 518173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LocalKnownZero = LocalKnownOne = APInt(GEPOpiBits, 0); 519173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(Index, LocalMask, 520173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner LocalKnownZero, LocalKnownOne, TD, Depth+1); 521173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TrailZ = std::min(TrailZ, 52279abedb83a4dd7d3583c7ca6df8283079acc3ba5Chris Lattner unsigned(CountTrailingZeros_64(TypeSize) + 52379abedb83a4dd7d3583c7ca6df8283079acc3ba5Chris Lattner LocalKnownZero.countTrailingOnes())); 524173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 525173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 526173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 527173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getLowBitsSet(BitWidth, TrailZ) & Mask; 528173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 529173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 530173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::PHI: { 531173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner PHINode *P = cast<PHINode>(I); 532173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Handle the case of a simple two-predecessor recurrence PHI. 533173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // There's a lot more that could theoretically be done here, but 534173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // this is sufficient to catch some interesting cases. 535173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (P->getNumIncomingValues() == 2) { 536173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner for (unsigned i = 0; i != 2; ++i) { 537173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *L = P->getIncomingValue(i); 538173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *R = P->getIncomingValue(!i); 539ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman Operator *LU = dyn_cast<Operator>(L); 540173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (!LU) 541173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner continue; 542ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman unsigned Opcode = LU->getOpcode(); 543173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Check for operations that have the property that if 544173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // both their operands have low zero bits, the result 545173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // will have low zero bits. 546173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Opcode == Instruction::Add || 547173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Opcode == Instruction::Sub || 548173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Opcode == Instruction::And || 549173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Opcode == Instruction::Or || 550173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Opcode == Instruction::Mul) { 551173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *LL = LU->getOperand(0); 552173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Value *LR = LU->getOperand(1); 553173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Find a recurrence. 554173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (LL == I) 555173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner L = LR; 556173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner else if (LR == I) 557173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner L = LL; 558173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner else 559173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 560173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Ok, we have a PHI of the form L op= R. Check for low 561173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // zero bits. 562173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask2 = APInt::getAllOnesValue(BitWidth); 563173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(R, Mask2, KnownZero2, KnownOne2, TD, Depth+1); 564173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask2 = APInt::getLowBitsSet(BitWidth, 565173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero2.countTrailingOnes()); 566c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene 567c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene // We need to take the minimum number of known bits 568c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene APInt KnownZero3(KnownZero), KnownOne3(KnownOne); 569c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene ComputeMaskedBits(L, Mask2, KnownZero3, KnownOne3, TD, Depth+1); 570c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene 571173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = Mask & 572173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt::getLowBitsSet(BitWidth, 573c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene std::min(KnownZero2.countTrailingOnes(), 574c714f1309049b2fd9e4ab68c8a7b480c63a4be0cDavid Greene KnownZero3.countTrailingOnes())); 575173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 576173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 577173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 578173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 5799004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman 5809004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // Otherwise take the unions of the known bit sets of the operands, 5819004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // taking conservative care to avoid excessive recursion. 5829004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman if (Depth < MaxDepth - 1 && !KnownZero && !KnownOne) { 5839004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownZero = APInt::getAllOnesValue(BitWidth); 5849004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownOne = APInt::getAllOnesValue(BitWidth); 5859004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman for (unsigned i = 0, e = P->getNumIncomingValues(); i != e; ++i) { 5869004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // Skip direct self references. 5879004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman if (P->getIncomingValue(i) == P) continue; 5889004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman 5899004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownZero2 = APInt(BitWidth, 0); 5909004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownOne2 = APInt(BitWidth, 0); 5919004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // Recurse, but cap the recursion to one level, because we don't 5929004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // want to waste time spinning around in loops. 5939004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman ComputeMaskedBits(P->getIncomingValue(i), KnownZero | KnownOne, 5949004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownZero2, KnownOne2, TD, MaxDepth-1); 5959004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownZero &= KnownZero2; 5969004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman KnownOne &= KnownOne2; 5979004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // If all bits have been ruled out, there's no need to check 5989004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman // more operands. 5999004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman if (!KnownZero && !KnownOne) 6009004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman break; 6019004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman } 6029004c8afd4bf7b3f27f4a4f8fd069379afa97c83Dan Gohman } 603173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 604173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 605173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Call: 606173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) { 607173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner switch (II->getIntrinsicID()) { 608173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner default: break; 609173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Intrinsic::ctpop: 610173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Intrinsic::ctlz: 611173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Intrinsic::cttz: { 612173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned LowBits = Log2_32(BitWidth)+1; 613173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner KnownZero = APInt::getHighBitsSet(BitWidth, BitWidth - LowBits); 614173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 615173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 616173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 617173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 618173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 619173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 620173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner} 621173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 622173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use 623173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// this predicate to simplify operations downstream. Mask is known to be zero 624173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// for bits that V cannot have. 625cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// 626cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// This function is defined on values with integer type, values with pointer 627cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// type (but only if TD is non-null), and vectors of integers. In the case 628cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// where V is a vector, the mask, known zero, and known one values are the 629cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// same width as the vector element, and the bit is set only if it is true 630cf5128ec01f45d2bf7eadc20b253cb44486e473fChris Lattner/// for all of the elements in the vector. 631173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattnerbool llvm::MaskedValueIsZero(Value *V, const APInt &Mask, 632846a2f2703f6bb894098274964faf5dce0b68c4dDan Gohman const TargetData *TD, unsigned Depth) { 633173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero(Mask.getBitWidth(), 0), KnownOne(Mask.getBitWidth(), 0); 634173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth); 635173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 636173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return (KnownZero & Mask) == Mask; 637173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner} 638173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 639173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 640173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 641173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// ComputeNumSignBits - Return the number of times the sign bit of the 642173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// register is replicated into the other bits. We know that at least 1 bit 643173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// is always equal to the sign bit (itself), but other cases can give us 644173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// information. For example, immediately after an "ashr X, 2", we know that 645173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// the top 3 bits are all equal to each other, so we return 3. 646173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// 647173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// 'Op' must have a scalar integer type. 648173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner/// 649846a2f2703f6bb894098274964faf5dce0b68c4dDan Gohmanunsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD, 650846a2f2703f6bb894098274964faf5dce0b68c4dDan Gohman unsigned Depth) { 651b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands assert((TD || V->getType()->isIntOrIntVectorTy()) && 652bd5ce52740700bb482fb2b5a03bce781acbf2941Dan Gohman "ComputeNumSignBits requires a TargetData object to operate " 653bd5ce52740700bb482fb2b5a03bce781acbf2941Dan Gohman "on non-integer values!"); 6546de29f8d960505421d61c80cdb738e16720b6c0eDan Gohman const Type *Ty = V->getType(); 655bd5ce52740700bb482fb2b5a03bce781acbf2941Dan Gohman unsigned TyBits = TD ? TD->getTypeSizeInBits(V->getType()->getScalarType()) : 656bd5ce52740700bb482fb2b5a03bce781acbf2941Dan Gohman Ty->getScalarSizeInBits(); 657173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned Tmp, Tmp2; 658173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner unsigned FirstAnswer = 1; 659173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 660d82e511aec0ea27ddd4c1e504b37f689796e965fChris Lattner // Note that ConstantInt is handled by the general ComputeMaskedBits case 661d82e511aec0ea27ddd4c1e504b37f689796e965fChris Lattner // below. 662d82e511aec0ea27ddd4c1e504b37f689796e965fChris Lattner 663173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Depth == 6) 664173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return 1; // Limit search depth. 665173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 666ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman Operator *U = dyn_cast<Operator>(V); 667ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman switch (Operator::getOpcode(V)) { 668173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner default: break; 669173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::SExt: 67069a008075b29fbe0644ccbeecf1418ef8cca5e24Mon P Wang Tmp = TyBits - U->getOperand(0)->getType()->getScalarSizeInBits(); 671173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return ComputeNumSignBits(U->getOperand(0), TD, Depth+1) + Tmp; 672173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 673173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::AShr: 674173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 675173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // ashr X, C -> adds C sign bits. 676173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *C = dyn_cast<ConstantInt>(U->getOperand(1))) { 677173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp += C->getZExtValue(); 678173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp > TyBits) Tmp = TyBits; 679173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 680173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return Tmp; 681173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Shl: 682173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *C = dyn_cast<ConstantInt>(U->getOperand(1))) { 683173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // shl destroys sign bits. 684173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 685173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (C->getZExtValue() >= TyBits || // Bad shift. 686173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner C->getZExtValue() >= Tmp) break; // Shifted all sign bits out. 687173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return Tmp - C->getZExtValue(); 688173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 689173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 690173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::And: 691173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Or: 692173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Xor: // NOT is handled here. 693173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Logical binary ops preserve the number of sign bits at the worst. 694173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 695173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp != 1) { 696173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); 697173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner FirstAnswer = std::min(Tmp, Tmp2); 698173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // We computed what we know about the sign bits as our first 699173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // answer. Now proceed to the generic code that uses 700173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // ComputeMaskedBits, and pick whichever answer is better. 701173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 702173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 703173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 704173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Select: 705173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); 706173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp == 1) return 1; // Early out. 707173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp2 = ComputeNumSignBits(U->getOperand(2), TD, Depth+1); 708173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return std::min(Tmp, Tmp2); 709173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 710173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Add: 711173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Add can have at most one carry bit. Thus we know that the output 712173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // is, at worst, one more bit than the inputs. 713173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 714173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp == 1) return 1; // Early out. 715173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 716173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Special case decrementing a value (ADD X, -1): 7170001e56f15215ae4bc5fffb82eec5c4828b888f0Dan Gohman if (ConstantInt *CRHS = dyn_cast<ConstantInt>(U->getOperand(1))) 718173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (CRHS->isAllOnesValue()) { 719173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0); 720173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask = APInt::getAllOnesValue(TyBits); 721173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(U->getOperand(0), Mask, KnownZero, KnownOne, TD, 722173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Depth+1); 723173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 724173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If the input is known to be 0 or 1, the output is 0/-1, which is all 725173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // sign bits set. 726173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if ((KnownZero | APInt(TyBits, 1)) == Mask) 727173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return TyBits; 728173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 729173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If we are subtracting one from a positive number, there is no carry 730173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // out of the result. 731173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero.isNegative()) 732173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return Tmp; 733173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 734173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 735173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); 736173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp2 == 1) return 1; 7378d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner return std::min(Tmp, Tmp2)-1; 738173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 739173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Sub: 740173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); 741173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp2 == 1) return 1; 742173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 743173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Handle NEG. 744173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (ConstantInt *CLHS = dyn_cast<ConstantInt>(U->getOperand(0))) 745173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (CLHS->isNullValue()) { 746173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0); 747173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask = APInt::getAllOnesValue(TyBits); 748173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(U->getOperand(1), Mask, KnownZero, KnownOne, 749173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner TD, Depth+1); 750173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If the input is known to be 0 or 1, the output is 0/-1, which is all 751173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // sign bits set. 752173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if ((KnownZero | APInt(TyBits, 1)) == Mask) 753173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return TyBits; 754173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 755173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // If the input is known to be positive (the sign bit is known clear), 756173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // the output of the NEG has the same number of sign bits as the input. 757173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero.isNegative()) 758173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return Tmp2; 759173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 760173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Otherwise, we treat this like a SUB. 761173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 762173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 763173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Sub can have at most one carry bit. Thus we know that the output 764173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // is, at worst, one more bit than the inputs. 765173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); 766173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (Tmp == 1) return 1; // Early out. 7678d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner return std::min(Tmp, Tmp2)-1; 7688d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner 7698d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner case Instruction::PHI: { 7708d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner PHINode *PN = cast<PHINode>(U); 7718d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner // Don't analyze large in-degree PHIs. 7728d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner if (PN->getNumIncomingValues() > 4) break; 7738d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner 7748d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner // Take the minimum of all incoming values. This can't infinitely loop 7758d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner // because of our depth threshold. 7768d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner Tmp = ComputeNumSignBits(PN->getIncomingValue(0), TD, Depth+1); 7778d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) { 7788d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner if (Tmp == 1) return Tmp; 7798d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner Tmp = std::min(Tmp, 7800af20d847ac89f797d613a8a4fc3e7127ccb0b36Evan Cheng ComputeNumSignBits(PN->getIncomingValue(i), TD, Depth+1)); 7818d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner } 7828d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner return Tmp; 7838d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner } 7848d10f9d4a836907d7bf048be507787a9233959c9Chris Lattner 785173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner case Instruction::Trunc: 786173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // FIXME: it's tricky to do anything useful for this, but it is an important 787173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // case for targets like X86. 788173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner break; 789173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 790173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 791173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Finally, if we can prove that the top bits of the result are 0's or 1's, 792173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // use this information. 793173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0); 794173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner APInt Mask = APInt::getAllOnesValue(TyBits); 795173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth); 796173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 797173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner if (KnownZero.isNegative()) { // sign bit is 0 798173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask = KnownZero; 799173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } else if (KnownOne.isNegative()) { // sign bit is 1; 800173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask = KnownOne; 801173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } else { 802173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Nothing known. 803173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return FirstAnswer; 804173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner } 805173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner 806173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Okay, we know that the sign bit in Mask is set. Use CLZ to determine 807173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // the number of identical bits in the top of the input value. 808173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask = ~Mask; 809173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner Mask <<= Mask.getBitWidth()-TyBits; 810173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // Return # leading zeros. We use 'min' here in case Val was zero before 811173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner // shifting. We don't want to return '64' as for an i32 "0". 812173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner return std::max(FirstAnswer, std::min(TyBits, Mask.countLeadingZeros())); 813173234a68fb6ece106e77da443d87f09d5906cb9Chris Lattner} 814833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 8152b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez/// ComputeMultiple - This function computes the integer multiple of Base that 8162b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez/// equals V. If successful, it returns true and returns the multiple in 8173dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman/// Multiple. If unsuccessful, it returns false. It looks 8182b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez/// through SExt instructions only if LookThroughSExt is true. 8192b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandezbool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, 8203dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman bool LookThroughSExt, unsigned Depth) { 8212b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez const unsigned MaxDepth = 6; 8222b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8233dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman assert(V && "No Value?"); 8242b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez assert(Depth <= MaxDepth && "Limit Search Depth"); 825b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands assert(V->getType()->isIntegerTy() && "Not integer or pointer type!"); 8262b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8272b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez const Type *T = V->getType(); 8282b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8293dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman ConstantInt *CI = dyn_cast<ConstantInt>(V); 8302b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8312b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Base == 0) 8322b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return false; 8332b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8342b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Base == 1) { 8352b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = V; 8362b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 8372b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 8382b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8392b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez ConstantExpr *CO = dyn_cast<ConstantExpr>(V); 8402b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Constant *BaseVal = ConstantInt::get(T, Base); 8412b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (CO && CO == BaseVal) { 8422b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // Multiple is 1. 8432b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = ConstantInt::get(T, 1); 8442b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 8452b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 8462b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8472b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (CI && CI->getZExtValue() % Base == 0) { 8482b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = ConstantInt::get(T, CI->getZExtValue() / Base); 8492b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 8502b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 8512b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8522b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Depth == MaxDepth) return false; // Limit search depth. 8532b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8542b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Operator *I = dyn_cast<Operator>(V); 8552b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (!I) return false; 8562b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8572b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez switch (I->getOpcode()) { 8582b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez default: break; 85911fe72661dac17efa1564ef6fc212acae4f0c07eChris Lattner case Instruction::SExt: 8602b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (!LookThroughSExt) return false; 8612b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // otherwise fall through to ZExt 86211fe72661dac17efa1564ef6fc212acae4f0c07eChris Lattner case Instruction::ZExt: 8633dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman return ComputeMultiple(I->getOperand(0), Base, Multiple, 8643dbb9e64d6e9d1e8bf16f75ebe4fe59ffdf93dd3Dan Gohman LookThroughSExt, Depth+1); 8652b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez case Instruction::Shl: 8662b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez case Instruction::Mul: { 8672b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Value *Op0 = I->getOperand(0); 8682b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Value *Op1 = I->getOperand(1); 8692b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8702b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (I->getOpcode() == Instruction::Shl) { 8712b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1); 8722b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (!Op1CI) return false; 8732b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // Turn Op0 << Op1 into Op0 * 2^Op1 8742b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez APInt Op1Int = Op1CI->getValue(); 8752b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez uint64_t BitToSet = Op1Int.getLimitedValue(Op1Int.getBitWidth() - 1); 876a99793c5ea24dd3839f4925b89b1f6acfcb24604Jay Foad APInt API(Op1Int.getBitWidth(), 0); 8777a874ddda037349184fbeb22838cc11a1a9bb78fJay Foad API.setBit(BitToSet); 878a99793c5ea24dd3839f4925b89b1f6acfcb24604Jay Foad Op1 = ConstantInt::get(V->getContext(), API); 8792b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 8802b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8812b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Value *Mul0 = NULL; 882e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (ComputeMultiple(Op0, Base, Mul0, LookThroughSExt, Depth+1)) { 883e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Constant *Op1C = dyn_cast<Constant>(Op1)) 884e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Constant *MulC = dyn_cast<Constant>(Mul0)) { 885e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Op1C->getType()->getPrimitiveSizeInBits() < 886e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC->getType()->getPrimitiveSizeInBits()) 887e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Op1C = ConstantExpr::getZExt(Op1C, MulC->getType()); 888e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Op1C->getType()->getPrimitiveSizeInBits() > 889e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC->getType()->getPrimitiveSizeInBits()) 890e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC = ConstantExpr::getZExt(MulC, Op1C->getType()); 891e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner 892e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner // V == Base * (Mul0 * Op1), so return (Mul0 * Op1) 893e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Multiple = ConstantExpr::getMul(MulC, Op1C); 894e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner return true; 895e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner } 8962b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 8972b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (ConstantInt *Mul0CI = dyn_cast<ConstantInt>(Mul0)) 8982b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Mul0CI->getValue() == 1) { 8992b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // V == Base * Op1, so return Op1 9002b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = Op1; 9012b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 9022b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 9032b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 9042b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 905e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Value *Mul1 = NULL; 906e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (ComputeMultiple(Op1, Base, Mul1, LookThroughSExt, Depth+1)) { 907e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Constant *Op0C = dyn_cast<Constant>(Op0)) 908e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Constant *MulC = dyn_cast<Constant>(Mul1)) { 909e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Op0C->getType()->getPrimitiveSizeInBits() < 910e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC->getType()->getPrimitiveSizeInBits()) 911e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Op0C = ConstantExpr::getZExt(Op0C, MulC->getType()); 912e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner if (Op0C->getType()->getPrimitiveSizeInBits() > 913e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC->getType()->getPrimitiveSizeInBits()) 914e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner MulC = ConstantExpr::getZExt(MulC, Op0C->getType()); 915e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner 916e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner // V == Base * (Mul1 * Op0), so return (Mul1 * Op0) 917e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner Multiple = ConstantExpr::getMul(MulC, Op0C); 918e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner return true; 919e971131695ac41afd56e82facddccc2807aa9bbdChris Lattner } 9202b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 9212b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (ConstantInt *Mul1CI = dyn_cast<ConstantInt>(Mul1)) 9222b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez if (Mul1CI->getValue() == 1) { 9232b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // V == Base * Op0, so return Op0 9242b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez Multiple = Op0; 9252b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return true; 9262b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 9272b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 9282b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 9292b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez } 9302b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 9312b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez // We could not determine if V is a multiple of Base. 9322b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez return false; 9332b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez} 9342b6705f5e7c7624bd7fe486298c400f1afc15f6cVictor Hernandez 935833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// CannotBeNegativeZero - Return true if we can prove that the specified FP 936833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// value is never equal to -0.0. 937833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// 938833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// NOTE: this function will need to be revisited when we support non-default 939833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// rounding modes! 940833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner/// 941833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattnerbool llvm::CannotBeNegativeZero(const Value *V, unsigned Depth) { 942833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (const ConstantFP *CFP = dyn_cast<ConstantFP>(V)) 943833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return !CFP->getValueAPF().isNegZero(); 944833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 945833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (Depth == 6) 946833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return 1; // Limit search depth. 947833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 948ca178908c8dc2303a1fb54a8a93bab0f0b964e11Dan Gohman const Operator *I = dyn_cast<Operator>(V); 949833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (I == 0) return false; 950833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 951833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner // (add x, 0.0) is guaranteed to return +0.0, not -0.0. 952ae3a0be92e33bc716722aa600983fc1535acb122Dan Gohman if (I->getOpcode() == Instruction::FAdd && 953833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner isa<ConstantFP>(I->getOperand(1)) && 954833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner cast<ConstantFP>(I->getOperand(1))->isNullValue()) 955833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return true; 956833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 957833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner // sitofp and uitofp turn into +0.0 for zero. 958833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (isa<SIToFPInst>(I) || isa<UIToFPInst>(I)) 959833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return true; 960833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 961833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) 962833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner // sqrt(-0.0) = -0.0, no other negative results are possible. 963833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (II->getIntrinsicID() == Intrinsic::sqrt) 96471339c965ca6268b9bff91213364783c3d06f666Gabor Greif return CannotBeNegativeZero(II->getArgOperand(0), Depth+1); 965833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 966833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (const CallInst *CI = dyn_cast<CallInst>(I)) 967833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (const Function *F = CI->getCalledFunction()) { 968833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner if (F->isDeclaration()) { 969f0443c1eb44d737d9bd78962932fc80f74c6113cDaniel Dunbar // abs(x) != -0.0 970f0443c1eb44d737d9bd78962932fc80f74c6113cDaniel Dunbar if (F->getName() == "abs") return true; 9719d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen // fabs[lf](x) != -0.0 9729d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen if (F->getName() == "fabs") return true; 9739d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen if (F->getName() == "fabsf") return true; 9749d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen if (F->getName() == "fabsl") return true; 9759d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen if (F->getName() == "sqrt" || F->getName() == "sqrtf" || 9769d06175a15a61b977ebbabd0d9cc738ebfa7870cDale Johannesen F->getName() == "sqrtl") 97771339c965ca6268b9bff91213364783c3d06f666Gabor Greif return CannotBeNegativeZero(CI->getArgOperand(0), Depth+1); 978833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner } 979833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner } 980833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 981833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner return false; 982833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner} 983833f25d79ee28f1049f9177c3d2f4c9fbad6f643Chris Lattner 984b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// This is the recursive version of BuildSubAggregate. It takes a few different 985b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// arguments. Idxs is the index within the nested struct From that we are 986b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// looking at now (which is of type IndexedType). IdxSkip is the number of 987b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// indices from Idxs that should be left out when inserting into the resulting 988b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// struct. To is the result struct built so far, new insertvalue instructions 989b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// build on that. 9907db949df789383acce98ef072f08794fdd5bd04eDan Gohmanstatic Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType, 9917db949df789383acce98ef072f08794fdd5bd04eDan Gohman SmallVector<unsigned, 10> &Idxs, 9927db949df789383acce98ef072f08794fdd5bd04eDan Gohman unsigned IdxSkip, 9937db949df789383acce98ef072f08794fdd5bd04eDan Gohman Instruction *InsertBefore) { 994b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman const llvm::StructType *STy = llvm::dyn_cast<llvm::StructType>(IndexedType); 995b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (STy) { 9960a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Save the original To argument so we can modify it 9970a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman Value *OrigTo = To; 998b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // General case, the type indexed by Idxs is a struct 999b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { 1000b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Process each struct element recursively 1001b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman Idxs.push_back(i); 10020a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman Value *PrevTo = To; 1003710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip, 1004ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky InsertBefore); 1005b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman Idxs.pop_back(); 10060a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman if (!To) { 10070a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Couldn't find any inserted value for this index? Cleanup 10080a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman while (PrevTo != OrigTo) { 10090a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman InsertValueInst* Del = cast<InsertValueInst>(PrevTo); 10100a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman PrevTo = Del->getAggregateOperand(); 10110a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman Del->eraseFromParent(); 10120a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman } 10130a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Stop processing elements 10140a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman break; 10150a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman } 1016b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } 10170a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // If we succesfully found a value for each of our subaggregates 10180a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman if (To) 10190a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman return To; 1020b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } 10210a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Base case, the type indexed by SourceIdxs is not a struct, or not all of 10220a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // the struct's elements had a value that was inserted directly. In the latter 10230a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // case, perhaps we can't determine each of the subelements individually, but 10240a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // we might be able to find the complete struct somewhere. 10250a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman 10260a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Find the value that is at that particular spot 1027ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky Value *V = FindInsertedValue(From, Idxs.begin(), Idxs.end()); 10280a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman 10290a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman if (!V) 10300a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman return NULL; 10310a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman 10320a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // Insert the value in the new (sub) aggregrate 10330a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman return llvm::InsertValueInst::Create(To, V, Idxs.begin() + IdxSkip, 10340a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman Idxs.end(), "tmp", InsertBefore); 1035b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman} 1036b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1037b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// This helper takes a nested struct and extracts a part of it (which is again a 1038b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// struct) into a new value. For example, given the struct: 1039b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// { a, { b, { c, d }, e } } 1040b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// and the indices "1, 1" this returns 1041b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// { c, d }. 1042b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// 10430a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// It does this by inserting an insertvalue for each element in the resulting 10440a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// struct, as opposed to just inserting a single struct. This will only work if 10450a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// each of the elements of the substruct are known (ie, inserted into From by an 10460a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// insertvalue instruction somewhere). 1047b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman// 10480a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman// All inserted insertvalue instructions are inserted before InsertBefore 10497db949df789383acce98ef072f08794fdd5bd04eDan Gohmanstatic Value *BuildSubAggregate(Value *From, const unsigned *idx_begin, 1050ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky const unsigned *idx_end, 10517db949df789383acce98ef072f08794fdd5bd04eDan Gohman Instruction *InsertBefore) { 1052977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman assert(InsertBefore && "Must have someplace to insert!"); 1053710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman const Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(), 1054710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman idx_begin, 1055710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman idx_end); 10569e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson Value *To = UndefValue::get(IndexedType); 1057b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman SmallVector<unsigned, 10> Idxs(idx_begin, idx_end); 1058b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman unsigned IdxSkip = Idxs.size(); 1059b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1060ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore); 1061b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman} 1062b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1063710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman/// FindInsertedValue - Given an aggregrate and an sequence of indices, see if 1064710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman/// the scalar value indexed is already around as a register, for example if it 1065710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman/// were inserted directly into the aggregrate. 10660a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman/// 10670a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman/// If InsertBefore is not null, this function will duplicate (modified) 10680a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman/// insertvalues when a part of a nested struct is extracted. 1069b23d5adbc8230167e711070b9298985de4580f30Matthijs KooijmanValue *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin, 1070ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky const unsigned *idx_end, Instruction *InsertBefore) { 1071b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Nothing to index? Just return V then (this is useful at the end of our 1072b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // recursion) 1073b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (idx_begin == idx_end) 1074b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman return V; 1075b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // We have indices, so V should have an indexable type 10761df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands assert((V->getType()->isStructTy() || V->getType()->isArrayTy()) 1077b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman && "Not looking at a struct or array?"); 1078b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman assert(ExtractValueInst::getIndexedType(V->getType(), idx_begin, idx_end) 1079b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman && "Invalid indices for type?"); 1080b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman const CompositeType *PTy = cast<CompositeType>(V->getType()); 108176f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson 1082b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (isa<UndefValue>(V)) 10839e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson return UndefValue::get(ExtractValueInst::getIndexedType(PTy, 1084b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman idx_begin, 1085b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman idx_end)); 1086b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman else if (isa<ConstantAggregateZero>(V)) 1087a7235ea7245028a0723e8ab7fd011386b3900777Owen Anderson return Constant::getNullValue(ExtractValueInst::getIndexedType(PTy, 108876f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson idx_begin, 108976f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson idx_end)); 1090b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman else if (Constant *C = dyn_cast<Constant>(V)) { 1091b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (isa<ConstantArray>(C) || isa<ConstantStruct>(C)) 1092b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Recursively process this constant 109376f600b205606a055ec35e7d3fd1a99602329d67Owen Anderson return FindInsertedValue(C->getOperand(*idx_begin), idx_begin + 1, 1094ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky idx_end, InsertBefore); 1095b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } else if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) { 1096b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Loop the indices for the insertvalue instruction in parallel with the 1097b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // requested indices 1098b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman const unsigned *req_idx = idx_begin; 1099710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman for (const unsigned *i = I->idx_begin(), *e = I->idx_end(); 1100710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman i != e; ++i, ++req_idx) { 11019954c76f2c89ab3c70bfe8222534621a86f9085aDuncan Sands if (req_idx == idx_end) { 1102977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman if (InsertBefore) 11030a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // The requested index identifies a part of a nested aggregate. Handle 11040a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // this specially. For example, 11050a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %A = insertvalue { i32, {i32, i32 } } undef, i32 10, 1, 0 11060a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %B = insertvalue { i32, {i32, i32 } } %A, i32 11, 1, 1 11070a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %C = extractvalue {i32, { i32, i32 } } %B, 1 11080a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // This can be changed into 11090a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %A = insertvalue {i32, i32 } undef, i32 10, 0 11100a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // %C = insertvalue {i32, i32 } %A, i32 11, 1 11110a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // which allows the unused 0,0 element from the nested struct to be 11120a9aaf46bee75540db16603dd60f7d3bc597842dMatthijs Kooijman // removed. 1113ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky return BuildSubAggregate(V, idx_begin, req_idx, InsertBefore); 1114977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman else 1115977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman // We can't handle this without inserting insertvalues 1116977289121996f0afb781592f92a4aee1be3010feMatthijs Kooijman return 0; 11179954c76f2c89ab3c70bfe8222534621a86f9085aDuncan Sands } 1118b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1119b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // This insert value inserts something else than what we are looking for. 1120b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // See if the (aggregrate) value inserted into has the value we are 1121b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // looking for, then. 1122b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman if (*req_idx != *i) 1123710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman return FindInsertedValue(I->getAggregateOperand(), idx_begin, idx_end, 1124ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky InsertBefore); 1125b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } 1126b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // If we end up here, the indices of the insertvalue match with those 1127b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // requested (though possibly only partially). Now we recursively look at 1128b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // the inserted value, passing any remaining indices. 1129710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman return FindInsertedValue(I->getInsertedValueOperand(), req_idx, idx_end, 1130ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky InsertBefore); 1131b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } else if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) { 1132b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // If we're extracting a value from an aggregrate that was extracted from 1133b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // something else, we can extract from that something else directly instead. 1134b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // However, we will need to chain I's indices with the requested indices. 1135b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1136b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Calculate the number of indices required 1137b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman unsigned size = I->getNumIndices() + (idx_end - idx_begin); 1138b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Allocate some space to put the new indices in 11393faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman SmallVector<unsigned, 5> Idxs; 11403faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman Idxs.reserve(size); 1141b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Add indices from the extract value instruction 1142710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman for (const unsigned *i = I->idx_begin(), *e = I->idx_end(); 11433faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman i != e; ++i) 11443faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman Idxs.push_back(*i); 1145b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 1146b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Add requested indices 11473faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman for (const unsigned *i = idx_begin, *e = idx_end; i != e; ++i) 11483faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman Idxs.push_back(*i); 1149b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 11503faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman assert(Idxs.size() == size 1151710eb236e67dc021c51ef5cb5d2eb8768840895aMatthijs Kooijman && "Number of indices added not correct?"); 1152b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman 11533faf9df08ff389028050bfbccbef571061bf7cc1Matthijs Kooijman return FindInsertedValue(I->getAggregateOperand(), Idxs.begin(), Idxs.end(), 1154ae3d802953b5209e7e9530cd5b5d4e457a6974dcNick Lewycky InsertBefore); 1155b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman } 1156b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // Otherwise, we don't know (such as, extracting from a function return value 1157b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman // or load instruction) 1158b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman return 0; 1159b23d5adbc8230167e711070b9298985de4580f30Matthijs Kooijman} 11600ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 1161ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner/// GetPointerBaseWithConstantOffset - Analyze the specified pointer to see if 1162ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner/// it can be expressed as a base pointer plus a constant offset. Return the 1163ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner/// base and offset to the caller. 1164ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris LattnerValue *llvm::GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset, 1165ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner const TargetData &TD) { 1166ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner Operator *PtrOp = dyn_cast<Operator>(Ptr); 1167ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (PtrOp == 0) return Ptr; 1168ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1169ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // Just look through bitcasts. 1170ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (PtrOp->getOpcode() == Instruction::BitCast) 1171ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner return GetPointerBaseWithConstantOffset(PtrOp->getOperand(0), Offset, TD); 1172ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1173ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // If this is a GEP with constant indices, we can look through it. 1174ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner GEPOperator *GEP = dyn_cast<GEPOperator>(PtrOp); 1175ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (GEP == 0 || !GEP->hasAllConstantIndices()) return Ptr; 1176ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1177ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner gep_type_iterator GTI = gep_type_begin(GEP); 1178ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner for (User::op_iterator I = GEP->idx_begin(), E = GEP->idx_end(); I != E; 1179ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner ++I, ++GTI) { 1180ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner ConstantInt *OpC = cast<ConstantInt>(*I); 1181ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (OpC->isZero()) continue; 1182ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1183ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // Handle a struct and array indices which add their offset to the pointer. 1184ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (const StructType *STy = dyn_cast<StructType>(*GTI)) { 1185ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); 1186ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner } else { 1187ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); 1188ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner Offset += OpC->getSExtValue()*Size; 1189ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner } 1190ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner } 1191ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1192ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // Re-sign extend from the pointer size if needed to get overflow edge cases 1193ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner // right. 1194ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner unsigned PtrSize = TD.getPointerSizeInBits(); 1195ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner if (PtrSize < 64) 1196ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner Offset = (Offset << (64-PtrSize)) >> (64-PtrSize); 1197ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1198ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner return GetPointerBaseWithConstantOffset(GEP->getPointerOperand(), Offset, TD); 1199ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner} 1200ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 1201ed58a6f96f605901adc0df3ca76499d52b2d1a1aChris Lattner 12020ff39b3feb10477c224138156941234f5fa46f58Evan Cheng/// GetConstantStringInfo - This function computes the length of a 12030ff39b3feb10477c224138156941234f5fa46f58Evan Cheng/// null-terminated C string pointed to by V. If successful, it returns true 12040ff39b3feb10477c224138156941234f5fa46f58Evan Cheng/// and returns the string in Str. If unsuccessful, it returns false. 12050a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohmanbool llvm::GetConstantStringInfo(const Value *V, std::string &Str, 12060a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman uint64_t Offset, 12070582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling bool StopAtNul) { 12080582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling // If V is NULL then return false; 12090582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (V == NULL) return false; 12100ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 12110ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Look through bitcast instructions. 12120a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman if (const BitCastInst *BCI = dyn_cast<BitCastInst>(V)) 12130582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return GetConstantStringInfo(BCI->getOperand(0), Str, Offset, StopAtNul); 12140582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling 12150ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // If the value is not a GEP instruction nor a constant expression with a 12160ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // GEP instruction, then return false because ConstantArray can't occur 12170ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // any other way 12180a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const User *GEP = 0; 12190a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) { 12200ff39b3feb10477c224138156941234f5fa46f58Evan Cheng GEP = GEPI; 12210a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 12220ff39b3feb10477c224138156941234f5fa46f58Evan Cheng if (CE->getOpcode() == Instruction::BitCast) 12230582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return GetConstantStringInfo(CE->getOperand(0), Str, Offset, StopAtNul); 12240582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (CE->getOpcode() != Instruction::GetElementPtr) 12250582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 12260ff39b3feb10477c224138156941234f5fa46f58Evan Cheng GEP = CE; 12270ff39b3feb10477c224138156941234f5fa46f58Evan Cheng } 12280ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 12290ff39b3feb10477c224138156941234f5fa46f58Evan Cheng if (GEP) { 12300ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Make sure the GEP has exactly three arguments. 12310582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (GEP->getNumOperands() != 3) 12320582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 12330582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling 12340ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Make sure the index-ee is a pointer to array of i8. 12350ff39b3feb10477c224138156941234f5fa46f58Evan Cheng const PointerType *PT = cast<PointerType>(GEP->getOperand(0)->getType()); 12360ff39b3feb10477c224138156941234f5fa46f58Evan Cheng const ArrayType *AT = dyn_cast<ArrayType>(PT->getElementType()); 1237b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands if (AT == 0 || !AT->getElementType()->isIntegerTy(8)) 12380582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 12390ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 12400ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Check to make sure that the first operand of the GEP is an integer and 12410ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // has value 0 so that we are sure we're indexing into the initializer. 12420a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const ConstantInt *FirstIdx = dyn_cast<ConstantInt>(GEP->getOperand(1)); 12430582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (FirstIdx == 0 || !FirstIdx->isZero()) 12440582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 12450ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 12460ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // If the second index isn't a ConstantInt, then this is a variable index 12470ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // into the array. If this occurs, we can't say anything meaningful about 12480ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // the string. 12490ff39b3feb10477c224138156941234f5fa46f58Evan Cheng uint64_t StartIdx = 0; 12500a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman if (const ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2))) 12510ff39b3feb10477c224138156941234f5fa46f58Evan Cheng StartIdx = CI->getZExtValue(); 12520582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling else 12530582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 12540582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return GetConstantStringInfo(GEP->getOperand(0), Str, StartIdx+Offset, 12550ff39b3feb10477c224138156941234f5fa46f58Evan Cheng StopAtNul); 12560ff39b3feb10477c224138156941234f5fa46f58Evan Cheng } 12570ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 12580ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // The GEP instruction, constant or instruction, must reference a global 12590ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // variable that is a constant and is initialized. The referenced constant 12600ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // initializer is the array that we'll use for optimization. 12610a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const GlobalVariable* GV = dyn_cast<GlobalVariable>(V); 12628255573835970e7130ba93271972172fb335f2ecDan Gohman if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer()) 12630582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 12640a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const Constant *GlobalInit = GV->getInitializer(); 12650ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 12660ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Handle the ConstantAggregateZero case 12670582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (isa<ConstantAggregateZero>(GlobalInit)) { 12680ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // This is a degenerate case. The initializer is constant zero so the 12690ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // length of the string must be zero. 12700582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling Str.clear(); 12710582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return true; 12720582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling } 12730ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 12740ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Must be a Constant Array 12750a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit); 1276b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands if (Array == 0 || !Array->getType()->getElementType()->isIntegerTy(8)) 12770582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 12780ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 12790ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Get the number of elements in the array 12800ff39b3feb10477c224138156941234f5fa46f58Evan Cheng uint64_t NumElts = Array->getType()->getNumElements(); 12810ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 12820582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (Offset > NumElts) 12830582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 12840ff39b3feb10477c224138156941234f5fa46f58Evan Cheng 12850ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // Traverse the constant array from 'Offset' which is the place the GEP refers 12860ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // to in the array. 12870582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling Str.reserve(NumElts-Offset); 12880ff39b3feb10477c224138156941234f5fa46f58Evan Cheng for (unsigned i = Offset; i != NumElts; ++i) { 12890a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const Constant *Elt = Array->getOperand(i); 12900a60fa33210202a38a59ae3ea8681216f234ce51Dan Gohman const ConstantInt *CI = dyn_cast<ConstantInt>(Elt); 12910582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling if (!CI) // This array isn't suitable, non-int initializer. 12920582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return false; 12930ff39b3feb10477c224138156941234f5fa46f58Evan Cheng if (StopAtNul && CI->isZero()) 12940582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return true; // we found end of string, success! 12950582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling Str += (char)CI->getZExtValue(); 12960ff39b3feb10477c224138156941234f5fa46f58Evan Cheng } 12970582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling 12980ff39b3feb10477c224138156941234f5fa46f58Evan Cheng // The array isn't null terminated, but maybe this is a memcpy, not a strcpy. 12990582ae99ba75a556d6ff63b254da327d32ba036fBill Wendling return true; 13000ff39b3feb10477c224138156941234f5fa46f58Evan Cheng} 130125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 130225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher// These next two are very similar to the above, but also look through PHI 130325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher// nodes. 130425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher// TODO: See if we can integrate these two together. 130525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 130625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher/// GetStringLengthH - If we can compute the length of the string pointed to by 130725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher/// the specified pointer, return 'len+1'. If we can't, return 0. 130825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopherstatic uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) { 130925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Look through noop bitcast instructions. 131025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (BitCastInst *BCI = dyn_cast<BitCastInst>(V)) 131125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return GetStringLengthH(BCI->getOperand(0), PHIs); 131225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 131325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If this is a PHI node, there are two cases: either we have already seen it 131425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // or we haven't. 131525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (PHINode *PN = dyn_cast<PHINode>(V)) { 131625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!PHIs.insert(PN)) 131725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return ~0ULL; // already in the set. 131825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 131925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If it was new, see if all the input strings are the same length. 132025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t LenSoFar = ~0ULL; 132125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 132225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs); 132325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len == 0) return 0; // Unknown length -> unknown. 132425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 132525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len == ~0ULL) continue; 132625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 132725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len != LenSoFar && LenSoFar != ~0ULL) 132825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; // Disagree -> unknown. 132925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher LenSoFar = Len; 133025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 133125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 133225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Success, all agree. 133325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return LenSoFar; 133425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 133525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 133625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y) 133725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (SelectInst *SI = dyn_cast<SelectInst>(V)) { 133825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs); 133925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len1 == 0) return 0; 134025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs); 134125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len2 == 0) return 0; 134225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len1 == ~0ULL) return Len2; 134325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len2 == ~0ULL) return Len1; 134425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (Len1 != Len2) return 0; 134525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return Len1; 134625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 134725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 134825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If the value is not a GEP instruction nor a constant expression with a 134925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // GEP instruction, then return unknown. 135025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher User *GEP = 0; 135125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) { 135225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher GEP = GEPI; 135325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 135425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (CE->getOpcode() != Instruction::GetElementPtr) 135525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 135625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher GEP = CE; 135725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } else { 135825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 135925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 136025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 136125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Make sure the GEP has exactly three arguments. 136225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (GEP->getNumOperands() != 3) 136325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 136425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 136525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Check to make sure that the first operand of the GEP is an integer and 136625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // has value 0 so that we are sure we're indexing into the initializer. 136725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) { 136825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!Idx->isZero()) 136925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 137025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } else 137125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 137225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 137325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If the second index isn't a ConstantInt, then this is a variable index 137425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // into the array. If this occurs, we can't say anything meaningful about 137525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // the string. 137625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t StartIdx = 0; 137725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2))) 137825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher StartIdx = CI->getZExtValue(); 137925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher else 138025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 138125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 138225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // The GEP instruction, constant or instruction, must reference a global 138325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // variable that is a constant and is initialized. The referenced constant 138425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // initializer is the array that we'll use for optimization. 138525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)); 138625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!GV || !GV->isConstant() || !GV->hasInitializer() || 138725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher GV->mayBeOverridden()) 138825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 138925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher Constant *GlobalInit = GV->getInitializer(); 139025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 139125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Handle the ConstantAggregateZero case, which is a degenerate case. The 139225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // initializer is constant zero so the length of the string must be zero. 139325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (isa<ConstantAggregateZero>(GlobalInit)) 139425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 1; // Len = 0 offset by 1. 139525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 139625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Must be a Constant Array 139725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit); 139825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!Array || !Array->getType()->getElementType()->isIntegerTy(8)) 139925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return false; 140025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 140125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Get the number of elements in the array 140225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t NumElts = Array->getType()->getNumElements(); 140325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 140425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // Traverse the constant array from StartIdx (derived above) which is 140525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // the place the GEP refers to in the array. 140625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher for (unsigned i = StartIdx; i != NumElts; ++i) { 140725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher Constant *Elt = Array->getOperand(i); 140825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher ConstantInt *CI = dyn_cast<ConstantInt>(Elt); 140925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!CI) // This array isn't suitable, non-int initializer. 141025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; 141125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (CI->isZero()) 141225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return i-StartIdx+1; // We found end of string, success! 141325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher } 141425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 141525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return 0; // The array isn't null terminated, conservatively return 'unknown'. 141625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher} 141725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 141825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher/// GetStringLength - If we can compute the length of the string pointed to by 141925ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher/// the specified pointer, return 'len+1'. If we can't, return 0. 142025ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopheruint64_t llvm::GetStringLength(Value *V) { 142125ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher if (!V->getType()->isPointerTy()) return 0; 142225ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher 142325ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher SmallPtrSet<PHINode*, 32> PHIs; 142425ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher uint64_t Len = GetStringLengthH(V, PHIs); 142525ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return 142625ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher // an empty string as a length. 142725ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher return Len == ~0ULL ? 1 : Len; 142825ec483cfca8d3a3ba8728a4a126e04b92789069Eric Christopher} 14295034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman 14305034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan GohmanValue *llvm::GetUnderlyingObject(Value *V, unsigned MaxLookup) { 14315034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman if (!V->getType()->isPointerTy()) 14325034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman return V; 14335034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) { 14345034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { 14355034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman V = GEP->getPointerOperand(); 14365034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } else if (Operator::getOpcode(V) == Instruction::BitCast) { 14375034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman V = cast<Operator>(V)->getOperand(0); 14385034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { 14395034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman if (GA->mayBeOverridden()) 14405034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman return V; 14415034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman V = GA->getAliasee(); 14425034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } else { 14435034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman return V; 14445034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } 14455034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman assert(V->getType()->isPointerTy() && "Unexpected operand type!"); 14465034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman } 14475034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman return V; 14485034dd318a9dfa0dc45a3ac01e58e60f2aa2498dDan Gohman} 1449