InstCombinePHI.cpp revision db125cfaf57cc83e7dd7453de2d509bc8efd0e5e
1f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner//===- InstCombinePHI.cpp -------------------------------------------------===// 2f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// 3f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// The LLVM Compiler Infrastructure 4f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// 5f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// This file is distributed under the University of Illinois Open Source 6f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// License. See LICENSE.TXT for details. 7f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// 8f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner//===----------------------------------------------------------------------===// 9f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// 10f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// This file implements the visitPHINode function. 11f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// 12f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner//===----------------------------------------------------------------------===// 13f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 14f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner#include "InstCombine.h" 15cd6636c737a82949ad13db2d0d918af6424fb78bDuncan Sands#include "llvm/Analysis/InstructionSimplify.h" 16f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner#include "llvm/Target/TargetData.h" 17f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner#include "llvm/ADT/SmallPtrSet.h" 18f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner#include "llvm/ADT/STLExtras.h" 19f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnerusing namespace llvm; 20f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 21f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// FoldPHIArgBinOpIntoPHI - If we have something like phi [add (a,b), add(a,c)] 22f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// and if a/b/c and the add's all have a single use, turn this into a phi 23f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// and a single binop. 24f54e72962991005a3c0cc7dce0c550a14af90792Chris LattnerInstruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) { 25f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0)); 26f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner assert(isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)); 27f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned Opc = FirstInst->getOpcode(); 28f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *LHSVal = FirstInst->getOperand(0); 29f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *RHSVal = FirstInst->getOperand(1); 30f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 31db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *LHSType = LHSVal->getType(); 32db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *RHSType = RHSVal->getType(); 33f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 34c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner bool isNUW = false, isNSW = false, isExact = false; 35c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (OverflowingBinaryOperator *BO = 36c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner dyn_cast<OverflowingBinaryOperator>(FirstInst)) { 37c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isNUW = BO->hasNoUnsignedWrap(); 38c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isNSW = BO->hasNoSignedWrap(); 39c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner } else if (PossiblyExactOperator *PEO = 40c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner dyn_cast<PossiblyExactOperator>(FirstInst)) 41c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isExact = PEO->isExact(); 42c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner 43f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Scan to see if all operands are the same opcode, and all have one use. 44f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) { 45f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i)); 46f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!I || I->getOpcode() != Opc || !I->hasOneUse() || 47f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Verify type of the LHS matches so we don't fold cmp's of different 48c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner // types. 49f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner I->getOperand(0)->getType() != LHSType || 50f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner I->getOperand(1)->getType() != RHSType) 51f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 52f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 53f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If they are CmpInst instructions, check their predicates 54c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (CmpInst *CI = dyn_cast<CmpInst>(I)) 55c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (CI->getPredicate() != cast<CmpInst>(FirstInst)->getPredicate()) 56f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 57f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 58c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isNUW) 59c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isNUW = cast<OverflowingBinaryOperator>(I)->hasNoUnsignedWrap(); 60c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isNSW) 61c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isNSW = cast<OverflowingBinaryOperator>(I)->hasNoSignedWrap(); 62c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isExact) 63c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isExact = cast<PossiblyExactOperator>(I)->isExact(); 64c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner 65f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Keep track of which operand needs a phi node. 66f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (I->getOperand(0) != LHSVal) LHSVal = 0; 67f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (I->getOperand(1) != RHSVal) RHSVal = 0; 68f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 69f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 70f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If both LHS and RHS would need a PHI, don't do this transformation, 71f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // because it would increase the number of PHIs entering the block, 72f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // which leads to higher register pressure. This is especially 73f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // bad when the PHIs are in the header of a loop. 74f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!LHSVal && !RHSVal) 75f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 76f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 77f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Otherwise, this is safe to transform! 78f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 79f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *InLHS = FirstInst->getOperand(0); 80f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *InRHS = FirstInst->getOperand(1); 81f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *NewLHS = 0, *NewRHS = 0; 82f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (LHSVal == 0) { 833ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad NewLHS = PHINode::Create(LHSType, PN.getNumIncomingValues(), 84f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner FirstInst->getOperand(0)->getName() + ".pn"); 85f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0)); 86f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InsertNewInstBefore(NewLHS, PN); 87f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LHSVal = NewLHS; 88f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 89f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 90f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (RHSVal == 0) { 913ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad NewRHS = PHINode::Create(RHSType, PN.getNumIncomingValues(), 92f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner FirstInst->getOperand(1)->getName() + ".pn"); 93f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0)); 94f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InsertNewInstBefore(NewRHS, PN); 95f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner RHSVal = NewRHS; 96f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 97f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 98f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Add all operands to the new PHIs. 99f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (NewLHS || NewRHS) { 100f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { 101f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *InInst = cast<Instruction>(PN.getIncomingValue(i)); 102f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (NewLHS) { 103f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *NewInLHS = InInst->getOperand(0); 104f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i)); 105f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 106f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (NewRHS) { 107f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *NewInRHS = InInst->getOperand(1); 108f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i)); 109f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 110f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 111f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 112f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 113a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst)) { 114a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman CmpInst *NewCI = CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(), 115a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman LHSVal, RHSVal); 116a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman NewCI->setDebugLoc(FirstInst->getDebugLoc()); 117a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman return NewCI; 118a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman } 119a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman 120c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner BinaryOperator *BinOp = cast<BinaryOperator>(FirstInst); 121c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner BinaryOperator *NewBinOp = 122c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner BinaryOperator::Create(BinOp->getOpcode(), LHSVal, RHSVal); 123c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isNUW) NewBinOp->setHasNoUnsignedWrap(); 124c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isNSW) NewBinOp->setHasNoSignedWrap(); 125c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isExact) NewBinOp->setIsExact(); 126a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman NewBinOp->setDebugLoc(FirstInst->getDebugLoc()); 127c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner return NewBinOp; 128f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 129f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 130f54e72962991005a3c0cc7dce0c550a14af90792Chris LattnerInstruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) { 131f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner GetElementPtrInst *FirstInst =cast<GetElementPtrInst>(PN.getIncomingValue(0)); 132f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 133f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallVector<Value*, 16> FixedOperands(FirstInst->op_begin(), 134f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner FirstInst->op_end()); 135f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // This is true if all GEP bases are allocas and if all indices into them are 136f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // constants. 137f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner bool AllBasePointersAreAllocas = true; 138f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 139f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // We don't want to replace this phi if the replacement would require 140f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // more than one phi, which leads to higher register pressure. This is 141f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // especially bad when the PHIs are in the header of a loop. 142f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner bool NeededPhi = false; 143f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 1444bd8217af3cf38f9fcce378fbc687162e28a7cf8Chris Lattner bool AllInBounds = true; 1454bd8217af3cf38f9fcce378fbc687162e28a7cf8Chris Lattner 146f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Scan to see if all operands are the same opcode, and all have one use. 147f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) { 148f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner GetElementPtrInst *GEP= dyn_cast<GetElementPtrInst>(PN.getIncomingValue(i)); 149f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!GEP || !GEP->hasOneUse() || GEP->getType() != FirstInst->getType() || 150f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner GEP->getNumOperands() != FirstInst->getNumOperands()) 151f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 152f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 1534bd8217af3cf38f9fcce378fbc687162e28a7cf8Chris Lattner AllInBounds &= GEP->isInBounds(); 1544bd8217af3cf38f9fcce378fbc687162e28a7cf8Chris Lattner 155f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Keep track of whether or not all GEPs are of alloca pointers. 156f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (AllBasePointersAreAllocas && 157f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner (!isa<AllocaInst>(GEP->getOperand(0)) || 158f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner !GEP->hasAllConstantIndices())) 159f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner AllBasePointersAreAllocas = false; 160f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 161f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Compare the operand lists. 162f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned op = 0, e = FirstInst->getNumOperands(); op != e; ++op) { 163f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (FirstInst->getOperand(op) == GEP->getOperand(op)) 164f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 165f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 166f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Don't merge two GEPs when two operands differ (introducing phi nodes) 167f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // if one of the PHIs has a constant for the index. The index may be 168f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // substantially cheaper to compute for the constants, so making it a 169f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // variable index could pessimize the path. This also handles the case 170f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // for struct indices, which must always be constant. 171f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isa<ConstantInt>(FirstInst->getOperand(op)) || 172f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner isa<ConstantInt>(GEP->getOperand(op))) 173f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 174f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 175f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (FirstInst->getOperand(op)->getType() !=GEP->getOperand(op)->getType()) 176f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 177f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 178f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If we already needed a PHI for an earlier operand, and another operand 179f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // also requires a PHI, we'd be introducing more PHIs than we're 180f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // eliminating, which increases register pressure on entry to the PHI's 181f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // block. 182f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (NeededPhi) 183f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 184f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 185f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner FixedOperands[op] = 0; // Needs a PHI. 186f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NeededPhi = true; 187f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 188f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 189f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 190f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If all of the base pointers of the PHI'd GEPs are from allocas, don't 191f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // bother doing this transformation. At best, this will just save a bit of 192f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // offset calculation, but all the predecessors will have to materialize the 193f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // stack address into a register anyway. We'd actually rather *clone* the 194f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // load up into the predecessors so that we have a load of a gep of an alloca, 195f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // which can usually all be folded into the load. 196f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (AllBasePointersAreAllocas) 197f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 198f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 199f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Otherwise, this is safe to transform. Insert PHI nodes for each operand 200f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // that is variable. 201f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallVector<PHINode*, 16> OperandPhis(FixedOperands.size()); 202f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 203f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner bool HasAnyPHIs = false; 204f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 0, e = FixedOperands.size(); i != e; ++i) { 205f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (FixedOperands[i]) continue; // operand doesn't need a phi. 206f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *FirstOp = FirstInst->getOperand(i); 2073ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad PHINode *NewPN = PHINode::Create(FirstOp->getType(), e, 208f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner FirstOp->getName()+".pn"); 209f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InsertNewInstBefore(NewPN, PN); 210f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 211f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewPN->addIncoming(FirstOp, PN.getIncomingBlock(0)); 212f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner OperandPhis[i] = NewPN; 213f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner FixedOperands[i] = NewPN; 214f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner HasAnyPHIs = true; 215f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 216f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 217f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 218f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Add all operands to the new PHIs. 219f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (HasAnyPHIs) { 220f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { 221f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner GetElementPtrInst *InGEP =cast<GetElementPtrInst>(PN.getIncomingValue(i)); 222f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner BasicBlock *InBB = PN.getIncomingBlock(i); 223f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 224f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned op = 0, e = OperandPhis.size(); op != e; ++op) 225f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *OpPhi = OperandPhis[op]) 226f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner OpPhi->addIncoming(InGEP->getOperand(op), InBB); 227f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 228f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 229f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 230f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *Base = FixedOperands[0]; 2314bd8217af3cf38f9fcce378fbc687162e28a7cf8Chris Lattner GetElementPtrInst *NewGEP = 232f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner GetElementPtrInst::Create(Base, FixedOperands.begin()+1, 233f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner FixedOperands.end()); 2341521e91fc442b5c27d56118b45248e3d5707f7e2Chris Lattner if (AllInBounds) NewGEP->setIsInBounds(); 235a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman NewGEP->setDebugLoc(FirstInst->getDebugLoc()); 2364bd8217af3cf38f9fcce378fbc687162e28a7cf8Chris Lattner return NewGEP; 237f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 238f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 239f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 240f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// isSafeAndProfitableToSinkLoad - Return true if we know that it is safe to 241f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// sink the load out of the block that defines it. This means that it must be 242f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// obvious the value of the load is not changed from the point of the load to 243f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// the end of the block it is in. 244f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// 2457a2bdde0a0eebcd2125055e0eacaca040f0b766cChris Lattner/// Finally, it is safe, but not profitable, to sink a load targeting a 246f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// non-address-taken alloca. Doing so will cause us to not promote the alloca 247f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// to a register. 248f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnerstatic bool isSafeAndProfitableToSinkLoad(LoadInst *L) { 249f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner BasicBlock::iterator BBI = L, E = L->getParent()->end(); 250f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 251f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (++BBI; BBI != E; ++BBI) 252f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (BBI->mayWriteToMemory()) 253f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 254f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 255f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Check for non-address taken alloca. If not address-taken already, it isn't 256f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // profitable to do this xform. 257f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) { 258f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner bool isAddressTaken = false; 259f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); 260f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner UI != E; ++UI) { 26140119ceeecafdd6d47bd7bb7f520262858b931dfGabor Greif User *U = *UI; 26240119ceeecafdd6d47bd7bb7f520262858b931dfGabor Greif if (isa<LoadInst>(U)) continue; 26340119ceeecafdd6d47bd7bb7f520262858b931dfGabor Greif if (StoreInst *SI = dyn_cast<StoreInst>(U)) { 264f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If storing TO the alloca, then the address isn't taken. 265f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (SI->getOperand(1) == AI) continue; 266f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 267f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner isAddressTaken = true; 268f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner break; 269f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 270f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 271f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!isAddressTaken && AI->isStaticAlloca()) 272f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 273f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 274f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 275f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If this load is a load from a GEP with a constant offset from an alloca, 276f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // then we don't want to sink it. In its present form, it will be 277f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // load [constant stack offset]. Sinking it will cause us to have to 278f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // materialize the stack addresses in each predecessor in a register only to 279f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // do a shared load from register in the successor. 280f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(L->getOperand(0))) 281f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (AllocaInst *AI = dyn_cast<AllocaInst>(GEP->getOperand(0))) 282f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (AI->isStaticAlloca() && GEP->hasAllConstantIndices()) 283f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 284f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 285f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return true; 286f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 287f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 288f54e72962991005a3c0cc7dce0c550a14af90792Chris LattnerInstruction *InstCombiner::FoldPHIArgLoadIntoPHI(PHINode &PN) { 289f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LoadInst *FirstLI = cast<LoadInst>(PN.getIncomingValue(0)); 290f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 291f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // When processing loads, we need to propagate two bits of information to the 292f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // sunk load: whether it is volatile, and what its alignment is. We currently 293f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // don't sink loads when some have their alignment specified and some don't. 294f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // visitLoadInst will propagate an alignment onto the load when TD is around, 295f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // and if TD isn't around, we can't handle the mixed case. 296f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner bool isVolatile = FirstLI->isVolatile(); 297f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned LoadAlignment = FirstLI->getAlignment(); 2984c5fb1a311a7a5e3ceb802f5b26329d30f2713b1Chris Lattner unsigned LoadAddrSpace = FirstLI->getPointerAddressSpace(); 299f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 300f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // We can't sink the load if the loaded value could be modified between the 301f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // load and the PHI. 302f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (FirstLI->getParent() != PN.getIncomingBlock(0) || 303f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner !isSafeAndProfitableToSinkLoad(FirstLI)) 304f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 305f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 306f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If the PHI is of volatile loads and the load block has multiple 307f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // successors, sinking it would remove a load of the volatile value from 308f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the path through the other successor. 309f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isVolatile && 310f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner FirstLI->getParent()->getTerminator()->getNumSuccessors() != 1) 311f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 312f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 313f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Check to see if all arguments are the same operation. 314f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { 315f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LoadInst *LI = dyn_cast<LoadInst>(PN.getIncomingValue(i)); 316f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!LI || !LI->hasOneUse()) 317f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 318f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 319f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // We can't sink the load if the loaded value could be modified between 320f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the load and the PHI. 321f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (LI->isVolatile() != isVolatile || 322f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LI->getParent() != PN.getIncomingBlock(i) || 3234c5fb1a311a7a5e3ceb802f5b26329d30f2713b1Chris Lattner LI->getPointerAddressSpace() != LoadAddrSpace || 324f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner !isSafeAndProfitableToSinkLoad(LI)) 325f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 326f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 327f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If some of the loads have an alignment specified but not all of them, 328f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // we can't do the transformation. 329f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if ((LoadAlignment != 0) != (LI->getAlignment() != 0)) 330f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 331f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 332f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LoadAlignment = std::min(LoadAlignment, LI->getAlignment()); 333f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 334f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If the PHI is of volatile loads and the load block has multiple 335f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // successors, sinking it would remove a load of the volatile value from 336f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the path through the other successor. 337f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isVolatile && 338f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LI->getParent()->getTerminator()->getNumSuccessors() != 1) 339f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 340f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 341f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 342f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Okay, they are all the same operation. Create a new PHI node of the 343f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // correct type, and PHI together all of the LHS's of the instructions. 344f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *NewPN = PHINode::Create(FirstLI->getOperand(0)->getType(), 3453ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad PN.getNumIncomingValues(), 346f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.getName()+".in"); 347f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 348f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *InVal = FirstLI->getOperand(0); 349f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewPN->addIncoming(InVal, PN.getIncomingBlock(0)); 350f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 351f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Add all operands to the new PHI. 352f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { 353f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *NewInVal = cast<LoadInst>(PN.getIncomingValue(i))->getOperand(0); 354f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (NewInVal != InVal) 355f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InVal = 0; 356f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i)); 357f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 358f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 359f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *PhiVal; 360f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (InVal) { 361f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // The new PHI unions all of the same values together. This is really 362f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // common, so we handle it intelligently here for compile-time speed. 363f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PhiVal = InVal; 364f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner delete NewPN; 365f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } else { 366f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InsertNewInstBefore(NewPN, PN); 367f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PhiVal = NewPN; 368f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 369f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 370f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If this was a volatile load that we are merging, make sure to loop through 371f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // and mark all the input loads as non-volatile. If we don't do this, we will 372f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // insert a new volatile load and the old ones will not be deletable. 373f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isVolatile) 374f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) 375f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false); 376f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 377a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman LoadInst *NewLI = new LoadInst(PhiVal, "", isVolatile, LoadAlignment); 378a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman NewLI->setDebugLoc(FirstLI->getDebugLoc()); 379a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman return NewLI; 380f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 381f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 382f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 383f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 384f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary" 385f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// operator and they all are only used by the PHI, PHI together their 386f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// inputs, and do the operation once, to the result of the PHI. 387f54e72962991005a3c0cc7dce0c550a14af90792Chris LattnerInstruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) { 388f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0)); 389f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 390f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isa<GetElementPtrInst>(FirstInst)) 391f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return FoldPHIArgGEPIntoPHI(PN); 392f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isa<LoadInst>(FirstInst)) 393f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return FoldPHIArgLoadIntoPHI(PN); 394f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 395f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Scan the instruction, looking for input operations that can be folded away. 396f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If all input operands to the phi are the same instruction (e.g. a cast from 397f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the same type or "+42") we can pull the operation through the PHI, reducing 398f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // code size and simplifying code. 399f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Constant *ConstantOp = 0; 400db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *CastSrcTy = 0; 401c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner bool isNUW = false, isNSW = false, isExact = false; 402f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 403f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isa<CastInst>(FirstInst)) { 404f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner CastSrcTy = FirstInst->getOperand(0)->getType(); 405f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 406f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Be careful about transforming integer PHIs. We don't want to pessimize 407f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the code by turning an i32 into an i1293. 4081df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (PN.getType()->isIntegerTy() && CastSrcTy->isIntegerTy()) { 409f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!ShouldChangeType(PN.getType(), CastSrcTy)) 410f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 411f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 412f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) { 413f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Can fold binop, compare or shift here if the RHS is a constant, 414f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // otherwise call FoldPHIArgBinOpIntoPHI. 415f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1)); 416f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (ConstantOp == 0) 417f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return FoldPHIArgBinOpIntoPHI(PN); 418c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner 419c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (OverflowingBinaryOperator *BO = 420c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner dyn_cast<OverflowingBinaryOperator>(FirstInst)) { 421c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isNUW = BO->hasNoUnsignedWrap(); 422c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isNSW = BO->hasNoSignedWrap(); 423c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner } else if (PossiblyExactOperator *PEO = 424c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner dyn_cast<PossiblyExactOperator>(FirstInst)) 425c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isExact = PEO->isExact(); 426f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } else { 427f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; // Cannot fold this operation. 428f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 429f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 430f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Check to see if all arguments are the same operation. 431f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { 432f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i)); 433f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (I == 0 || !I->hasOneUse() || !I->isSameOperationAs(FirstInst)) 434f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 435f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (CastSrcTy) { 436f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (I->getOperand(0)->getType() != CastSrcTy) 437f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; // Cast operation must match. 438f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } else if (I->getOperand(1) != ConstantOp) { 439f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 440f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 441c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner 442c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isNUW) 443c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isNUW = cast<OverflowingBinaryOperator>(I)->hasNoUnsignedWrap(); 444c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isNSW) 445c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isNSW = cast<OverflowingBinaryOperator>(I)->hasNoSignedWrap(); 446c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isExact) 447c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isExact = cast<PossiblyExactOperator>(I)->isExact(); 448f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 449f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 450f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Okay, they are all the same operation. Create a new PHI node of the 451f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // correct type, and PHI together all of the LHS's of the instructions. 452f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *NewPN = PHINode::Create(FirstInst->getOperand(0)->getType(), 4533ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad PN.getNumIncomingValues(), 454f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.getName()+".in"); 455f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 456f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *InVal = FirstInst->getOperand(0); 457f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewPN->addIncoming(InVal, PN.getIncomingBlock(0)); 458f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 459f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Add all operands to the new PHI. 460f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { 461f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0); 462f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (NewInVal != InVal) 463f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InVal = 0; 464f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i)); 465f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 466f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 467f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *PhiVal; 468f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (InVal) { 469f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // The new PHI unions all of the same values together. This is really 470f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // common, so we handle it intelligently here for compile-time speed. 471f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PhiVal = InVal; 472f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner delete NewPN; 473f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } else { 474f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InsertNewInstBefore(NewPN, PN); 475f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PhiVal = NewPN; 476f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 477f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 478f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Insert and return the new operation. 479a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman if (CastInst *FirstCI = dyn_cast<CastInst>(FirstInst)) { 480a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman CastInst *NewCI = CastInst::Create(FirstCI->getOpcode(), PhiVal, 481a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman PN.getType()); 482a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman NewCI->setDebugLoc(FirstInst->getDebugLoc()); 483a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman return NewCI; 484a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman } 485f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 486c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst)) { 487c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner BinOp = BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp); 488c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isNUW) BinOp->setHasNoUnsignedWrap(); 489c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isNSW) BinOp->setHasNoSignedWrap(); 490c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isExact) BinOp->setIsExact(); 491a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman BinOp->setDebugLoc(FirstInst->getDebugLoc()); 492c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner return BinOp; 493c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner } 494f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 495f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner CmpInst *CIOp = cast<CmpInst>(FirstInst); 496a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman CmpInst *NewCI = CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(), 497a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman PhiVal, ConstantOp); 498a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman NewCI->setDebugLoc(FirstInst->getDebugLoc()); 499a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman return NewCI; 500f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 501f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 502f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle 503f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// that is dead. 504f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnerstatic bool DeadPHICycle(PHINode *PN, 505f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) { 506f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PN->use_empty()) return true; 507f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!PN->hasOneUse()) return false; 508f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 509f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Remember this node, and if we find the cycle, return. 510f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!PotentiallyDeadPHIs.insert(PN)) 511f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return true; 512f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 513f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Don't scan crazily complex things. 514f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PotentiallyDeadPHIs.size() == 16) 515f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 516f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 517f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *PU = dyn_cast<PHINode>(PN->use_back())) 518f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return DeadPHICycle(PU, PotentiallyDeadPHIs); 519f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 520f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 521f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 522f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 523f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// PHIsEqualValue - Return true if this phi node is always equal to 524f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// NonPhiInVal. This happens with mutually cyclic phi nodes like: 525f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// z = some value; x = phi (y, z); y = phi (x, z) 526f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnerstatic bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal, 527f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallPtrSet<PHINode*, 16> &ValueEqualPHIs) { 528f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // See if we already saw this PHI node. 529f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!ValueEqualPHIs.insert(PN)) 530f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return true; 531f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 532f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Don't scan crazily complex things. 533f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (ValueEqualPHIs.size() == 16) 534f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 535f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 536f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Scan the operands to see if they are either phi nodes or are equal to 537f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the value. 538f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 539f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *Op = PN->getIncomingValue(i); 540f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *OpPN = dyn_cast<PHINode>(Op)) { 541f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs)) 542f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 543f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } else if (Op != NonPhiInVal) 544f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 545f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 546f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 547f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return true; 548f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 549f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 550f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 551f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnernamespace { 552f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnerstruct PHIUsageRecord { 553f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned PHIId; // The ID # of the PHI (something determinstic to sort on) 554f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned Shift; // The amount shifted. 555f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *Inst; // The trunc instruction. 556f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 557f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIUsageRecord(unsigned pn, unsigned Sh, Instruction *User) 558f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner : PHIId(pn), Shift(Sh), Inst(User) {} 559f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 560f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner bool operator<(const PHIUsageRecord &RHS) const { 561f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIId < RHS.PHIId) return true; 562f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIId > RHS.PHIId) return false; 563f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (Shift < RHS.Shift) return true; 564f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (Shift > RHS.Shift) return false; 565f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return Inst->getType()->getPrimitiveSizeInBits() < 566f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner RHS.Inst->getType()->getPrimitiveSizeInBits(); 567f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 568f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner}; 569f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 570f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnerstruct LoweredPHIRecord { 571f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *PN; // The PHI that was lowered. 572f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned Shift; // The amount shifted. 573f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned Width; // The width extracted. 574f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 575db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner LoweredPHIRecord(PHINode *pn, unsigned Sh, Type *Ty) 576f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner : PN(pn), Shift(Sh), Width(Ty->getPrimitiveSizeInBits()) {} 577f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 578f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Ctor form used by DenseMap. 579f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LoweredPHIRecord(PHINode *pn, unsigned Sh) 580f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner : PN(pn), Shift(Sh), Width(0) {} 581f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner}; 582f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 583f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 584f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnernamespace llvm { 585f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner template<> 586f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner struct DenseMapInfo<LoweredPHIRecord> { 587f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner static inline LoweredPHIRecord getEmptyKey() { 588f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return LoweredPHIRecord(0, 0); 589f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 590f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner static inline LoweredPHIRecord getTombstoneKey() { 591f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return LoweredPHIRecord(0, 1); 592f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 593f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner static unsigned getHashValue(const LoweredPHIRecord &Val) { 594f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return DenseMapInfo<PHINode*>::getHashValue(Val.PN) ^ (Val.Shift>>3) ^ 595f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner (Val.Width>>3); 596f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 597f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner static bool isEqual(const LoweredPHIRecord &LHS, 598f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner const LoweredPHIRecord &RHS) { 599f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return LHS.PN == RHS.PN && LHS.Shift == RHS.Shift && 600f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LHS.Width == RHS.Width; 601f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 602f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner }; 603f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner template <> 604f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner struct isPodLike<LoweredPHIRecord> { static const bool value = true; }; 605f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 606f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 607f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 608f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// SliceUpIllegalIntegerPHI - This is an integer PHI and we know that it has an 609f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// illegal type: see if it is only used by trunc or trunc(lshr) operations. If 610f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// so, we split the PHI into the various pieces being extracted. This sort of 611f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// thing is introduced when SROA promotes an aggregate to large integer values. 612f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// 613f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// TODO: The user of the trunc may be an bitcast to float/double/vector or an 614f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// inttoptr. We should produce new PHIs in the right type. 615f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// 616f54e72962991005a3c0cc7dce0c550a14af90792Chris LattnerInstruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &FirstPhi) { 617f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // PHIUsers - Keep track of all of the truncated values extracted from a set 618f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // of PHIs, along with their offset. These are the things we want to rewrite. 619f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallVector<PHIUsageRecord, 16> PHIUsers; 620f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 621f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // PHIs are often mutually cyclic, so we keep track of a whole set of PHI 622f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // nodes which are extracted from. PHIsToSlice is a set we use to avoid 623f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // revisiting PHIs, PHIsInspected is a ordered list of PHIs that we need to 624f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // check the uses of (to ensure they are all extracts). 625f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallVector<PHINode*, 8> PHIsToSlice; 626f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallPtrSet<PHINode*, 8> PHIsInspected; 627f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 628f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIsToSlice.push_back(&FirstPhi); 629f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIsInspected.insert(&FirstPhi); 630f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 631f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned PHIId = 0; PHIId != PHIsToSlice.size(); ++PHIId) { 632f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *PN = PHIsToSlice[PHIId]; 633f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 634f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Scan the input list of the PHI. If any input is an invoke, and if the 635f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // input is defined in the predecessor, then we won't be split the critical 636f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // edge which is required to insert a truncate. Because of this, we have to 637f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // bail out. 638f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 639f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InvokeInst *II = dyn_cast<InvokeInst>(PN->getIncomingValue(i)); 640f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (II == 0) continue; 641f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (II->getParent() != PN->getIncomingBlock(i)) 642f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 643f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 644f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If we have a phi, and if it's directly in the predecessor, then we have 645f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // a critical edge where we need to put the truncate. Since we can't 646f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // split the edge in instcombine, we have to bail out. 647f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 648f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 649f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 650f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 651f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end(); 652f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner UI != E; ++UI) { 653f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *User = cast<Instruction>(*UI); 654f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 655f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If the user is a PHI, inspect its uses recursively. 656f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *UserPN = dyn_cast<PHINode>(User)) { 657f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIsInspected.insert(UserPN)) 658f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIsToSlice.push_back(UserPN); 659f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 660f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 661f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 662f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Truncates are always ok. 663f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isa<TruncInst>(User)) { 664f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIUsers.push_back(PHIUsageRecord(PHIId, 0, User)); 665f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 666f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 667f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 668f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Otherwise it must be a lshr which can only be used by one trunc. 669f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (User->getOpcode() != Instruction::LShr || 670f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner !User->hasOneUse() || !isa<TruncInst>(User->use_back()) || 671f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner !isa<ConstantInt>(User->getOperand(1))) 672f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 673f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 674f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned Shift = cast<ConstantInt>(User->getOperand(1))->getZExtValue(); 675f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIUsers.push_back(PHIUsageRecord(PHIId, Shift, User->use_back())); 676f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 677f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 678f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 679f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If we have no users, they must be all self uses, just nuke the PHI. 680f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIUsers.empty()) 681f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return ReplaceInstUsesWith(FirstPhi, UndefValue::get(FirstPhi.getType())); 682f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 683f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If this phi node is transformable, create new PHIs for all the pieces 684f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // extracted out of it. First, sort the users by their offset and size. 685f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner array_pod_sort(PHIUsers.begin(), PHIUsers.end()); 686f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 687f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner DEBUG(errs() << "SLICING UP PHI: " << FirstPhi << '\n'; 688f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i) 689f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner errs() << "AND USER PHI #" << i << ": " << *PHIsToSlice[i] <<'\n'; 690f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ); 691f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 692f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // PredValues - This is a temporary used when rewriting PHI nodes. It is 693f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // hoisted out here to avoid construction/destruction thrashing. 694f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner DenseMap<BasicBlock*, Value*> PredValues; 695f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 696f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // ExtractedVals - Each new PHI we introduce is saved here so we don't 697f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // introduce redundant PHIs. 698f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner DenseMap<LoweredPHIRecord, PHINode*> ExtractedVals; 699f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 700f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned UserI = 0, UserE = PHIUsers.size(); UserI != UserE; ++UserI) { 701f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned PHIId = PHIUsers[UserI].PHIId; 702f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *PN = PHIsToSlice[PHIId]; 703f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned Offset = PHIUsers[UserI].Shift; 704db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *Ty = PHIUsers[UserI].Inst->getType(); 705f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 706f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *EltPHI; 707f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 708f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If we've already lowered a user like this, reuse the previously lowered 709f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // value. 710f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if ((EltPHI = ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)]) == 0) { 711f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 712f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Otherwise, Create the new PHI node for this user. 7133ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad EltPHI = PHINode::Create(Ty, PN->getNumIncomingValues(), 7143ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad PN->getName()+".off"+Twine(Offset), PN); 715f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner assert(EltPHI->getType() != PN->getType() && 716f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner "Truncate didn't shrink phi?"); 717f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 718f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 719f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner BasicBlock *Pred = PN->getIncomingBlock(i); 720f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *&PredVal = PredValues[Pred]; 721f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 722f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If we already have a value for this predecessor, reuse it. 723f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PredVal) { 724f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner EltPHI->addIncoming(PredVal, Pred); 725f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 726f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 727f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 728f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Handle the PHI self-reuse case. 729f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *InVal = PN->getIncomingValue(i); 730f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (InVal == PN) { 731f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PredVal = EltPHI; 732f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner EltPHI->addIncoming(PredVal, Pred); 733f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 734f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 735f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 736f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *InPHI = dyn_cast<PHINode>(PN)) { 737f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If the incoming value was a PHI, and if it was one of the PHIs we 738f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // already rewrote it, just use the lowered value. 739f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (Value *Res = ExtractedVals[LoweredPHIRecord(InPHI, Offset, Ty)]) { 740f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PredVal = Res; 741f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner EltPHI->addIncoming(PredVal, Pred); 742f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 743f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 744f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 745f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 746f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Otherwise, do an extract in the predecessor. 747f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Builder->SetInsertPoint(Pred, Pred->getTerminator()); 748f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *Res = InVal; 749f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (Offset) 750f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Res = Builder->CreateLShr(Res, ConstantInt::get(InVal->getType(), 751f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Offset), "extract"); 752f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Res = Builder->CreateTrunc(Res, Ty, "extract.t"); 753f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PredVal = Res; 754f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner EltPHI->addIncoming(Res, Pred); 755f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 756f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If the incoming value was a PHI, and if it was one of the PHIs we are 757f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // rewriting, we will ultimately delete the code we inserted. This 758f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // means we need to revisit that PHI to make sure we extract out the 759f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // needed piece. 760f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *OldInVal = dyn_cast<PHINode>(PN->getIncomingValue(i))) 761f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIsInspected.count(OldInVal)) { 762f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned RefPHIId = std::find(PHIsToSlice.begin(),PHIsToSlice.end(), 763f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner OldInVal)-PHIsToSlice.begin(); 764f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIUsers.push_back(PHIUsageRecord(RefPHIId, Offset, 765f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner cast<Instruction>(Res))); 766f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ++UserE; 767f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 768f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 769f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PredValues.clear(); 770f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 771f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner DEBUG(errs() << " Made element PHI for offset " << Offset << ": " 772f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner << *EltPHI << '\n'); 773f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)] = EltPHI; 774f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 775f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 776f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Replace the use of this piece with the PHI node. 777f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ReplaceInstUsesWith(*PHIUsers[UserI].Inst, EltPHI); 778f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 779f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 780f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Replace all the remaining uses of the PHI nodes (self uses and the lshrs) 781f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // with undefs. 782f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *Undef = UndefValue::get(FirstPhi.getType()); 783f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i) 784f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ReplaceInstUsesWith(*PHIsToSlice[i], Undef); 785f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return ReplaceInstUsesWith(FirstPhi, Undef); 786f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 787f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 788f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// PHINode simplification 789f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// 790f54e72962991005a3c0cc7dce0c550a14af90792Chris LattnerInstruction *InstCombiner::visitPHINode(PHINode &PN) { 791cd6636c737a82949ad13db2d0d918af6424fb78bDuncan Sands if (Value *V = SimplifyInstruction(&PN, TD)) 792f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return ReplaceInstUsesWith(PN, V); 793f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 794f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If all PHI operands are the same operation, pull them through the PHI, 795f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // reducing code size. 796f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isa<Instruction>(PN.getIncomingValue(0)) && 797f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner isa<Instruction>(PN.getIncomingValue(1)) && 798f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner cast<Instruction>(PN.getIncomingValue(0))->getOpcode() == 799f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner cast<Instruction>(PN.getIncomingValue(1))->getOpcode() && 800f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // FIXME: The hasOneUse check will fail for PHIs that use the value more 801f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // than themselves more than once. 802f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.getIncomingValue(0)->hasOneUse()) 803f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (Instruction *Result = FoldPHIArgOpIntoPHI(PN)) 804f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return Result; 805f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 806f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If this is a trivial cycle in the PHI node graph, remove it. Basically, if 807f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // this PHI only has a single use (a PHI), and if that PHI only has one use (a 808f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // PHI)... break the cycle. 809f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PN.hasOneUse()) { 810f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *PHIUser = cast<Instruction>(PN.use_back()); 811f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) { 812f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs; 813f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PotentiallyDeadPHIs.insert(&PN); 814f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (DeadPHICycle(PU, PotentiallyDeadPHIs)) 815f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType())); 816f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 817f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 818f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If this phi has a single use, and if that use just computes a value for 819f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the next iteration of a loop, delete the phi. This occurs with unused 820f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // induction variables, e.g. "for (int j = 0; ; ++j);". Detecting this 821f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // common case here is good because the only other things that catch this 822f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // are induction variable analysis (sometimes) and ADCE, which is only run 823f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // late. 824f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIUser->hasOneUse() && 825f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) && 826f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIUser->use_back() == &PN) { 827f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType())); 828f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 829f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 830f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 831f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // We sometimes end up with phi cycles that non-obviously end up being the 832f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // same value, for example: 833f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // z = some value; x = phi (y, z); y = phi (x, z) 834f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // where the phi nodes don't necessarily need to be in the same block. Do a 835f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // quick check to see if the PHI node only contains a single non-phi value, if 836f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // so, scan to see if the phi cycle is actually equal to that value. 837f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner { 83886f72a8002ef6049d17ae8b9a536dee18b101fd0Frits van Bommel unsigned InValNo = 0, NumIncomingVals = PN.getNumIncomingValues(); 839f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Scan for the first non-phi operand. 84086f72a8002ef6049d17ae8b9a536dee18b101fd0Frits van Bommel while (InValNo != NumIncomingVals && 841f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner isa<PHINode>(PN.getIncomingValue(InValNo))) 842f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ++InValNo; 843f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 84486f72a8002ef6049d17ae8b9a536dee18b101fd0Frits van Bommel if (InValNo != NumIncomingVals) { 8454130278fbee97b9cd1ea4069e9c666bbe89d61f9Jay Foad Value *NonPhiInVal = PN.getIncomingValue(InValNo); 846f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 847f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Scan the rest of the operands to see if there are any conflicts, if so 848f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // there is no need to recursively scan other phis. 84986f72a8002ef6049d17ae8b9a536dee18b101fd0Frits van Bommel for (++InValNo; InValNo != NumIncomingVals; ++InValNo) { 850f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *OpVal = PN.getIncomingValue(InValNo); 851f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal)) 852f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner break; 853f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 854f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 855f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If we scanned over all operands, then we have one unique value plus 856f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // phi values. Scan PHI nodes to see if they all merge in each other or 857f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the value. 85886f72a8002ef6049d17ae8b9a536dee18b101fd0Frits van Bommel if (InValNo == NumIncomingVals) { 859f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallPtrSet<PHINode*, 16> ValueEqualPHIs; 860f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs)) 861f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return ReplaceInstUsesWith(PN, NonPhiInVal); 862f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 863f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 864f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 865f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 866f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If there are multiple PHIs, sort their operands so that they all list 867f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the blocks in the same order. This will help identical PHIs be eliminated 868f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // by other passes. Other passes shouldn't depend on this for correctness 869f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // however. 870f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *FirstPN = cast<PHINode>(PN.getParent()->begin()); 871f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (&PN != FirstPN) 872f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 0, e = FirstPN->getNumIncomingValues(); i != e; ++i) { 873f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner BasicBlock *BBA = PN.getIncomingBlock(i); 874f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner BasicBlock *BBB = FirstPN->getIncomingBlock(i); 875f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (BBA != BBB) { 876f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *VA = PN.getIncomingValue(i); 877f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned j = PN.getBasicBlockIndex(BBB); 878f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *VB = PN.getIncomingValue(j); 879f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.setIncomingBlock(i, BBB); 880f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.setIncomingValue(i, VB); 881f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.setIncomingBlock(j, BBA); 882f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.setIncomingValue(j, VA); 883f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // NOTE: Instcombine normally would want us to "return &PN" if we 884f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // modified any of the operands of an instruction. However, since we 885f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // aren't adding or removing uses (just rearranging them) we don't do 886f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // this in this case. 887f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 888f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 889f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 890f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If this is an integer PHI and we know that it has an illegal type, see if 891f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // it is only used by trunc or trunc(lshr) operations. If so, we split the 892f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // PHI into the various pieces being extracted. This sort of thing is 893f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // introduced when SROA promotes an aggregate to a single large integer type. 8941df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (PN.getType()->isIntegerTy() && TD && 895f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner !TD->isLegalInteger(PN.getType()->getPrimitiveSizeInBits())) 896f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (Instruction *Res = SliceUpIllegalIntegerPHI(PN)) 897f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return Res; 898f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 899f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 900eade00209447c07953a609b30666ce5f6d9f9864Benjamin Kramer} 901