InstCombinePHI.cpp revision 596aa123f46158639c836f1d53b89a9d7898c4b7
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" 15d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/ADT/STLExtras.h" 16d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/ADT/SmallPtrSet.h" 17cd6636c737a82949ad13db2d0d918af6424fb78bDuncan Sands#include "llvm/Analysis/InstructionSimplify.h" 180b8c9a80f20772c3793201ab5b251d3520b9cea3Chandler Carruth#include "llvm/IR/DataLayout.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); 3003fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 31db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *LHSType = LHSVal->getType(); 32db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *RHSType = RHSVal->getType(); 3303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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(); 4203fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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; 5703fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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(); 6403fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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; 7603fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 77f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Otherwise, this is safe to transform! 7803fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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 } 8903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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 } 9703fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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 } 11203fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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)); 13203fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 13303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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; 14303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 1444bd8217af3cf38f9fcce378fbc687162e28a7cf8Chris Lattner bool AllInBounds = true; 14503fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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(); 15403fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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; 16003fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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; 16503fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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; 17403fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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 } 18903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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; 19803fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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()); 20203fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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); 21003fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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 21703fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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); 22303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 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 } 22903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 230f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *Base = FixedOperands[0]; 23103fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach GetElementPtrInst *NewGEP = 2322eb40f6d86ab44e7e642ea665afb28604008d367Frits van Bommel GetElementPtrInst::Create(Base, makeArrayRef(FixedOperands).slice(1)); 2331521e91fc442b5c27d56118b45248e3d5707f7e2Chris Lattner if (AllInBounds) NewGEP->setIsInBounds(); 234a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman NewGEP->setDebugLoc(FirstInst->getDebugLoc()); 2354bd8217af3cf38f9fcce378fbc687162e28a7cf8Chris Lattner return NewGEP; 236f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 237f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 238f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 239f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// isSafeAndProfitableToSinkLoad - Return true if we know that it is safe to 240f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// sink the load out of the block that defines it. This means that it must be 241f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// obvious the value of the load is not changed from the point of the load to 242f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// the end of the block it is in. 243f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// 2447a2bdde0a0eebcd2125055e0eacaca040f0b766cChris Lattner/// Finally, it is safe, but not profitable, to sink a load targeting a 245f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// non-address-taken alloca. Doing so will cause us to not promote the alloca 246f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// to a register. 247f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnerstatic bool isSafeAndProfitableToSinkLoad(LoadInst *L) { 248f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner BasicBlock::iterator BBI = L, E = L->getParent()->end(); 24903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 250f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (++BBI; BBI != E; ++BBI) 251f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (BBI->mayWriteToMemory()) 252f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 25303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 254f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Check for non-address taken alloca. If not address-taken already, it isn't 255f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // profitable to do this xform. 256f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) { 257f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner bool isAddressTaken = false; 258f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); 259f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner UI != E; ++UI) { 26040119ceeecafdd6d47bd7bb7f520262858b931dfGabor Greif User *U = *UI; 26140119ceeecafdd6d47bd7bb7f520262858b931dfGabor Greif if (isa<LoadInst>(U)) continue; 26240119ceeecafdd6d47bd7bb7f520262858b931dfGabor Greif if (StoreInst *SI = dyn_cast<StoreInst>(U)) { 263f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If storing TO the alloca, then the address isn't taken. 264f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (SI->getOperand(1) == AI) continue; 265f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 266f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner isAddressTaken = true; 267f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner break; 268f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 26903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 270f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!isAddressTaken && AI->isStaticAlloca()) 271f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 272f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 27303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 274f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If this load is a load from a GEP with a constant offset from an alloca, 275f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // then we don't want to sink it. In its present form, it will be 276f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // load [constant stack offset]. Sinking it will cause us to have to 277f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // materialize the stack addresses in each predecessor in a register only to 278f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // do a shared load from register in the successor. 279f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(L->getOperand(0))) 280f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (AllocaInst *AI = dyn_cast<AllocaInst>(GEP->getOperand(0))) 281f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (AI->isStaticAlloca() && GEP->hasAllConstantIndices()) 282f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 28303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 284f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return true; 285f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 286f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 287f54e72962991005a3c0cc7dce0c550a14af90792Chris LattnerInstruction *InstCombiner::FoldPHIArgLoadIntoPHI(PHINode &PN) { 288f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LoadInst *FirstLI = cast<LoadInst>(PN.getIncomingValue(0)); 289cc4a0435b7ee34af2c64a6f7ee63642f56096d1bEli Friedman 290cc4a0435b7ee34af2c64a6f7ee63642f56096d1bEli Friedman // FIXME: This is overconservative; this transform is allowed in some cases 291cc4a0435b7ee34af2c64a6f7ee63642f56096d1bEli Friedman // for atomic operations. 292cc4a0435b7ee34af2c64a6f7ee63642f56096d1bEli Friedman if (FirstLI->isAtomic()) 293cc4a0435b7ee34af2c64a6f7ee63642f56096d1bEli Friedman return 0; 294cc4a0435b7ee34af2c64a6f7ee63642f56096d1bEli Friedman 295f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // When processing loads, we need to propagate two bits of information to the 296f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // sunk load: whether it is volatile, and what its alignment is. We currently 297f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // don't sink loads when some have their alignment specified and some don't. 298f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // visitLoadInst will propagate an alignment onto the load when TD is around, 299f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // and if TD isn't around, we can't handle the mixed case. 300f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner bool isVolatile = FirstLI->isVolatile(); 301f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned LoadAlignment = FirstLI->getAlignment(); 3024c5fb1a311a7a5e3ceb802f5b26329d30f2713b1Chris Lattner unsigned LoadAddrSpace = FirstLI->getPointerAddressSpace(); 30303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 304f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // We can't sink the load if the loaded value could be modified between the 305f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // load and the PHI. 306f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (FirstLI->getParent() != PN.getIncomingBlock(0) || 307f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner !isSafeAndProfitableToSinkLoad(FirstLI)) 308f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 30903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 310f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If the PHI is of volatile loads and the load block has multiple 311f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // successors, sinking it would remove a load of the volatile value from 312f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the path through the other successor. 31303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach if (isVolatile && 314f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner FirstLI->getParent()->getTerminator()->getNumSuccessors() != 1) 315f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 31603fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 317f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Check to see if all arguments are the same operation. 318f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { 319f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LoadInst *LI = dyn_cast<LoadInst>(PN.getIncomingValue(i)); 320f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!LI || !LI->hasOneUse()) 321f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 32203fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 32303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach // We can't sink the load if the loaded value could be modified between 324f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the load and the PHI. 325f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (LI->isVolatile() != isVolatile || 326f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LI->getParent() != PN.getIncomingBlock(i) || 3274c5fb1a311a7a5e3ceb802f5b26329d30f2713b1Chris Lattner LI->getPointerAddressSpace() != LoadAddrSpace || 328f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner !isSafeAndProfitableToSinkLoad(LI)) 329f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 33003fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 331f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If some of the loads have an alignment specified but not all of them, 332f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // we can't do the transformation. 333f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if ((LoadAlignment != 0) != (LI->getAlignment() != 0)) 334f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 33503fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 336f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LoadAlignment = std::min(LoadAlignment, LI->getAlignment()); 33703fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 338f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If the PHI is of volatile loads and the load block has multiple 339f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // successors, sinking it would remove a load of the volatile value from 340f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the path through the other successor. 341f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isVolatile && 342f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LI->getParent()->getTerminator()->getNumSuccessors() != 1) 343f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 344f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 34503fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 346f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Okay, they are all the same operation. Create a new PHI node of the 347f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // correct type, and PHI together all of the LHS's of the instructions. 348f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *NewPN = PHINode::Create(FirstLI->getOperand(0)->getType(), 3493ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad PN.getNumIncomingValues(), 350f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.getName()+".in"); 35103fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 352f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *InVal = FirstLI->getOperand(0); 353f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewPN->addIncoming(InVal, PN.getIncomingBlock(0)); 35403fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 355f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Add all operands to the new PHI. 356f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { 357f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *NewInVal = cast<LoadInst>(PN.getIncomingValue(i))->getOperand(0); 358f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (NewInVal != InVal) 359f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InVal = 0; 360f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i)); 361f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 36203fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 363f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *PhiVal; 364f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (InVal) { 365f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // The new PHI unions all of the same values together. This is really 366f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // common, so we handle it intelligently here for compile-time speed. 367f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PhiVal = InVal; 368f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner delete NewPN; 369f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } else { 370f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InsertNewInstBefore(NewPN, PN); 371f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PhiVal = NewPN; 372f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 37303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 374f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If this was a volatile load that we are merging, make sure to loop through 375f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // and mark all the input loads as non-volatile. If we don't do this, we will 376f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // insert a new volatile load and the old ones will not be deletable. 377f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isVolatile) 378f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) 379f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false); 38003fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 381a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman LoadInst *NewLI = new LoadInst(PhiVal, "", isVolatile, LoadAlignment); 382a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman NewLI->setDebugLoc(FirstLI->getDebugLoc()); 383a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman return NewLI; 384f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 385f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 386f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 387f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 388f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary" 389f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// operator and they all are only used by the PHI, PHI together their 390f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// inputs, and do the operation once, to the result of the PHI. 391f54e72962991005a3c0cc7dce0c550a14af90792Chris LattnerInstruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) { 392f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0)); 393f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 394f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isa<GetElementPtrInst>(FirstInst)) 395f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return FoldPHIArgGEPIntoPHI(PN); 396f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isa<LoadInst>(FirstInst)) 397f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return FoldPHIArgLoadIntoPHI(PN); 39803fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 399f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Scan the instruction, looking for input operations that can be folded away. 400f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If all input operands to the phi are the same instruction (e.g. a cast from 401f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the same type or "+42") we can pull the operation through the PHI, reducing 402f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // code size and simplifying code. 403f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Constant *ConstantOp = 0; 404db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *CastSrcTy = 0; 405c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner bool isNUW = false, isNSW = false, isExact = false; 40603fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 407f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isa<CastInst>(FirstInst)) { 408f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner CastSrcTy = FirstInst->getOperand(0)->getType(); 409f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 410f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Be careful about transforming integer PHIs. We don't want to pessimize 411f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the code by turning an i32 into an i1293. 4121df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (PN.getType()->isIntegerTy() && CastSrcTy->isIntegerTy()) { 413f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!ShouldChangeType(PN.getType(), CastSrcTy)) 414f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 415f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 416f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) { 41703fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach // Can fold binop, compare or shift here if the RHS is a constant, 418f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // otherwise call FoldPHIArgBinOpIntoPHI. 419f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1)); 420f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (ConstantOp == 0) 421f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return FoldPHIArgBinOpIntoPHI(PN); 42203fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 423c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (OverflowingBinaryOperator *BO = 424c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner dyn_cast<OverflowingBinaryOperator>(FirstInst)) { 425c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isNUW = BO->hasNoUnsignedWrap(); 426c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isNSW = BO->hasNoSignedWrap(); 427c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner } else if (PossiblyExactOperator *PEO = 428c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner dyn_cast<PossiblyExactOperator>(FirstInst)) 429c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isExact = PEO->isExact(); 430f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } else { 431f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; // Cannot fold this operation. 432f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 433f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 434f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Check to see if all arguments are the same operation. 435f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { 436f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i)); 437f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (I == 0 || !I->hasOneUse() || !I->isSameOperationAs(FirstInst)) 438f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 439f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (CastSrcTy) { 440f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (I->getOperand(0)->getType() != CastSrcTy) 441f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; // Cast operation must match. 442f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } else if (I->getOperand(1) != ConstantOp) { 443f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 444f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 44503fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 446c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isNUW) 447c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isNUW = cast<OverflowingBinaryOperator>(I)->hasNoUnsignedWrap(); 448c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isNSW) 449c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isNSW = cast<OverflowingBinaryOperator>(I)->hasNoSignedWrap(); 450c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isExact) 451c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner isExact = cast<PossiblyExactOperator>(I)->isExact(); 452f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 453f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 454f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Okay, they are all the same operation. Create a new PHI node of the 455f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // correct type, and PHI together all of the LHS's of the instructions. 456f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *NewPN = PHINode::Create(FirstInst->getOperand(0)->getType(), 4573ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad PN.getNumIncomingValues(), 458f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.getName()+".in"); 459f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 460f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *InVal = FirstInst->getOperand(0); 461f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewPN->addIncoming(InVal, PN.getIncomingBlock(0)); 462f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 463f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Add all operands to the new PHI. 464f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { 465f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0); 466f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (NewInVal != InVal) 467f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InVal = 0; 468f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i)); 469f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 470f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 471f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *PhiVal; 472f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (InVal) { 473f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // The new PHI unions all of the same values together. This is really 474f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // common, so we handle it intelligently here for compile-time speed. 475f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PhiVal = InVal; 476f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner delete NewPN; 477f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } else { 478f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InsertNewInstBefore(NewPN, PN); 479f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PhiVal = NewPN; 480f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 481f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 482f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Insert and return the new operation. 483a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman if (CastInst *FirstCI = dyn_cast<CastInst>(FirstInst)) { 484a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman CastInst *NewCI = CastInst::Create(FirstCI->getOpcode(), PhiVal, 485a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman PN.getType()); 486a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman NewCI->setDebugLoc(FirstInst->getDebugLoc()); 487a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman return NewCI; 488a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman } 48903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 490c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst)) { 491c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner BinOp = BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp); 492c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isNUW) BinOp->setHasNoUnsignedWrap(); 493c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isNSW) BinOp->setHasNoSignedWrap(); 494c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner if (isExact) BinOp->setIsExact(); 495a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman BinOp->setDebugLoc(FirstInst->getDebugLoc()); 496c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner return BinOp; 497c8cb8ef9c2d5e354db661022d707a19b3533c00eChris Lattner } 49803fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 499f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner CmpInst *CIOp = cast<CmpInst>(FirstInst); 500a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman CmpInst *NewCI = CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(), 501a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman PhiVal, ConstantOp); 502a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman NewCI->setDebugLoc(FirstInst->getDebugLoc()); 503a311c34d2af7c750f016ef5e4c41bee77a1dfac7Eli Friedman return NewCI; 504f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 505f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 506f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle 507f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// that is dead. 508f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnerstatic bool DeadPHICycle(PHINode *PN, 509f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) { 510f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PN->use_empty()) return true; 511f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!PN->hasOneUse()) return false; 512f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 513f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Remember this node, and if we find the cycle, return. 514f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!PotentiallyDeadPHIs.insert(PN)) 515f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return true; 51603fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 517f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Don't scan crazily complex things. 518f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PotentiallyDeadPHIs.size() == 16) 519f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 520f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 521f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *PU = dyn_cast<PHINode>(PN->use_back())) 522f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return DeadPHICycle(PU, PotentiallyDeadPHIs); 523f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 524f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 525f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 526f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 527f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// PHIsEqualValue - Return true if this phi node is always equal to 528f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// NonPhiInVal. This happens with mutually cyclic phi nodes like: 529f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// z = some value; x = phi (y, z); y = phi (x, z) 53003fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbachstatic bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal, 531f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallPtrSet<PHINode*, 16> &ValueEqualPHIs) { 532f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // See if we already saw this PHI node. 533f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!ValueEqualPHIs.insert(PN)) 534f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return true; 53503fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 536f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Don't scan crazily complex things. 537f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (ValueEqualPHIs.size() == 16) 538f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 53903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 540f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Scan the operands to see if they are either phi nodes or are equal to 541f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the value. 542f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 543f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *Op = PN->getIncomingValue(i); 544f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *OpPN = dyn_cast<PHINode>(Op)) { 545f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs)) 546f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 547f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } else if (Op != NonPhiInVal) 548f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return false; 549f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 55003fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 551f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return true; 552f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 553f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 554f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 555f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnernamespace { 556f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnerstruct PHIUsageRecord { 557f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned PHIId; // The ID # of the PHI (something determinstic to sort on) 558f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned Shift; // The amount shifted. 559f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *Inst; // The trunc instruction. 56003fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 561f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIUsageRecord(unsigned pn, unsigned Sh, Instruction *User) 562f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner : PHIId(pn), Shift(Sh), Inst(User) {} 56303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 564f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner bool operator<(const PHIUsageRecord &RHS) const { 565f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIId < RHS.PHIId) return true; 566f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIId > RHS.PHIId) return false; 567f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (Shift < RHS.Shift) return true; 568f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (Shift > RHS.Shift) return false; 569f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return Inst->getType()->getPrimitiveSizeInBits() < 570f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner RHS.Inst->getType()->getPrimitiveSizeInBits(); 571f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 572f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner}; 57303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 574f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnerstruct LoweredPHIRecord { 575f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *PN; // The PHI that was lowered. 576f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned Shift; // The amount shifted. 577f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned Width; // The width extracted. 57803fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 579db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner LoweredPHIRecord(PHINode *pn, unsigned Sh, Type *Ty) 580f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner : PN(pn), Shift(Sh), Width(Ty->getPrimitiveSizeInBits()) {} 58103fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 582f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Ctor form used by DenseMap. 583f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LoweredPHIRecord(PHINode *pn, unsigned Sh) 584f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner : PN(pn), Shift(Sh), Width(0) {} 585f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner}; 586f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 587f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 588f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattnernamespace llvm { 589f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner template<> 590f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner struct DenseMapInfo<LoweredPHIRecord> { 591f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner static inline LoweredPHIRecord getEmptyKey() { 592f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return LoweredPHIRecord(0, 0); 593f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 594f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner static inline LoweredPHIRecord getTombstoneKey() { 595f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return LoweredPHIRecord(0, 1); 596f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 597f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner static unsigned getHashValue(const LoweredPHIRecord &Val) { 598f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return DenseMapInfo<PHINode*>::getHashValue(Val.PN) ^ (Val.Shift>>3) ^ 599f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner (Val.Width>>3); 600f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 601f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner static bool isEqual(const LoweredPHIRecord &LHS, 602f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner const LoweredPHIRecord &RHS) { 603f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return LHS.PN == RHS.PN && LHS.Shift == RHS.Shift && 604f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner LHS.Width == RHS.Width; 605f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 606f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner }; 607f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner template <> 608f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner struct isPodLike<LoweredPHIRecord> { static const bool value = true; }; 609f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 610f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 611f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 612f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// SliceUpIllegalIntegerPHI - This is an integer PHI and we know that it has an 613f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// illegal type: see if it is only used by trunc or trunc(lshr) operations. If 614f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// so, we split the PHI into the various pieces being extracted. This sort of 615f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// thing is introduced when SROA promotes an aggregate to large integer values. 616f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// 617f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// TODO: The user of the trunc may be an bitcast to float/double/vector or an 618f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// inttoptr. We should produce new PHIs in the right type. 619f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner/// 620f54e72962991005a3c0cc7dce0c550a14af90792Chris LattnerInstruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &FirstPhi) { 621f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // PHIUsers - Keep track of all of the truncated values extracted from a set 622f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // of PHIs, along with their offset. These are the things we want to rewrite. 623f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallVector<PHIUsageRecord, 16> PHIUsers; 62403fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 625f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // PHIs are often mutually cyclic, so we keep track of a whole set of PHI 626f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // nodes which are extracted from. PHIsToSlice is a set we use to avoid 627f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // revisiting PHIs, PHIsInspected is a ordered list of PHIs that we need to 628f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // check the uses of (to ensure they are all extracts). 629f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallVector<PHINode*, 8> PHIsToSlice; 630f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallPtrSet<PHINode*, 8> PHIsInspected; 63103fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 632f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIsToSlice.push_back(&FirstPhi); 633f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIsInspected.insert(&FirstPhi); 63403fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 635f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned PHIId = 0; PHIId != PHIsToSlice.size(); ++PHIId) { 636f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *PN = PHIsToSlice[PHIId]; 63703fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 638f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Scan the input list of the PHI. If any input is an invoke, and if the 639f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // input is defined in the predecessor, then we won't be split the critical 640f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // edge which is required to insert a truncate. Because of this, we have to 641f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // bail out. 642f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 643f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner InvokeInst *II = dyn_cast<InvokeInst>(PN->getIncomingValue(i)); 644f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (II == 0) continue; 645f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (II->getParent() != PN->getIncomingBlock(i)) 646f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 64703fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 648f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If we have a phi, and if it's directly in the predecessor, then we have 649f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // a critical edge where we need to put the truncate. Since we can't 650f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // split the edge in instcombine, we have to bail out. 651f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 652f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 65303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 65403fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 655f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end(); 656f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner UI != E; ++UI) { 657f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *User = cast<Instruction>(*UI); 65803fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 659f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If the user is a PHI, inspect its uses recursively. 660f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *UserPN = dyn_cast<PHINode>(User)) { 661f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIsInspected.insert(UserPN)) 662f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIsToSlice.push_back(UserPN); 663f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 664f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 66503fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 666f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Truncates are always ok. 667f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isa<TruncInst>(User)) { 668f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIUsers.push_back(PHIUsageRecord(PHIId, 0, User)); 669f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 670f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 67103fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 672f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Otherwise it must be a lshr which can only be used by one trunc. 673f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (User->getOpcode() != Instruction::LShr || 674f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner !User->hasOneUse() || !isa<TruncInst>(User->use_back()) || 675f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner !isa<ConstantInt>(User->getOperand(1))) 676f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 67703fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 678f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned Shift = cast<ConstantInt>(User->getOperand(1))->getZExtValue(); 679f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIUsers.push_back(PHIUsageRecord(PHIId, Shift, User->use_back())); 680f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 681f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 68203fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 683f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If we have no users, they must be all self uses, just nuke the PHI. 684f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIUsers.empty()) 685f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return ReplaceInstUsesWith(FirstPhi, UndefValue::get(FirstPhi.getType())); 68603fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 687f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If this phi node is transformable, create new PHIs for all the pieces 688f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // extracted out of it. First, sort the users by their offset and size. 689f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner array_pod_sort(PHIUsers.begin(), PHIUsers.end()); 69003fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 691596aa123f46158639c836f1d53b89a9d7898c4b7Matt Arsenault DEBUG(dbgs() << "SLICING UP PHI: " << FirstPhi << '\n'; 692596aa123f46158639c836f1d53b89a9d7898c4b7Matt Arsenault for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i) 693596aa123f46158639c836f1d53b89a9d7898c4b7Matt Arsenault dbgs() << "AND USER PHI #" << i << ": " << *PHIsToSlice[i] << '\n'; 694596aa123f46158639c836f1d53b89a9d7898c4b7Matt Arsenault ); 69503fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 696f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // PredValues - This is a temporary used when rewriting PHI nodes. It is 697f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // hoisted out here to avoid construction/destruction thrashing. 698f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner DenseMap<BasicBlock*, Value*> PredValues; 69903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 700f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // ExtractedVals - Each new PHI we introduce is saved here so we don't 701f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // introduce redundant PHIs. 702f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner DenseMap<LoweredPHIRecord, PHINode*> ExtractedVals; 70303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 704f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned UserI = 0, UserE = PHIUsers.size(); UserI != UserE; ++UserI) { 705f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned PHIId = PHIUsers[UserI].PHIId; 706f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *PN = PHIsToSlice[PHIId]; 707f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned Offset = PHIUsers[UserI].Shift; 708db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *Ty = PHIUsers[UserI].Inst->getType(); 70903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 710f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *EltPHI; 71103fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 712f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If we've already lowered a user like this, reuse the previously lowered 713f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // value. 714f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if ((EltPHI = ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)]) == 0) { 71503fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 716f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Otherwise, Create the new PHI node for this user. 7173ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad EltPHI = PHINode::Create(Ty, PN->getNumIncomingValues(), 7183ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad PN->getName()+".off"+Twine(Offset), PN); 719f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner assert(EltPHI->getType() != PN->getType() && 720f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner "Truncate didn't shrink phi?"); 72103fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 722f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 723f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner BasicBlock *Pred = PN->getIncomingBlock(i); 724f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *&PredVal = PredValues[Pred]; 72503fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 726f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If we already have a value for this predecessor, reuse it. 727f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PredVal) { 728f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner EltPHI->addIncoming(PredVal, Pred); 729f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 730f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 731f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 732f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Handle the PHI self-reuse case. 733f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *InVal = PN->getIncomingValue(i); 734f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (InVal == PN) { 735f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PredVal = EltPHI; 736f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner EltPHI->addIncoming(PredVal, Pred); 737f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 738f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 73903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 740f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *InPHI = dyn_cast<PHINode>(PN)) { 741f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If the incoming value was a PHI, and if it was one of the PHIs we 742f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // already rewrote it, just use the lowered value. 743f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (Value *Res = ExtractedVals[LoweredPHIRecord(InPHI, Offset, Ty)]) { 744f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PredVal = Res; 745f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner EltPHI->addIncoming(PredVal, Pred); 746f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner continue; 747f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 748f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 74903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 750f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Otherwise, do an extract in the predecessor. 751f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Builder->SetInsertPoint(Pred, Pred->getTerminator()); 752f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *Res = InVal; 753f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (Offset) 754f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Res = Builder->CreateLShr(Res, ConstantInt::get(InVal->getType(), 755f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Offset), "extract"); 756f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Res = Builder->CreateTrunc(Res, Ty, "extract.t"); 757f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PredVal = Res; 758f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner EltPHI->addIncoming(Res, Pred); 75903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 760f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If the incoming value was a PHI, and if it was one of the PHIs we are 761f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // rewriting, we will ultimately delete the code we inserted. This 762f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // means we need to revisit that PHI to make sure we extract out the 763f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // needed piece. 764f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *OldInVal = dyn_cast<PHINode>(PN->getIncomingValue(i))) 765f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIsInspected.count(OldInVal)) { 766f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned RefPHIId = std::find(PHIsToSlice.begin(),PHIsToSlice.end(), 767f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner OldInVal)-PHIsToSlice.begin(); 76803fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach PHIUsers.push_back(PHIUsageRecord(RefPHIId, Offset, 769f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner cast<Instruction>(Res))); 770f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ++UserE; 771f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 772f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 773f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PredValues.clear(); 77403fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 775596aa123f46158639c836f1d53b89a9d7898c4b7Matt Arsenault DEBUG(dbgs() << " Made element PHI for offset " << Offset << ": " 776f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner << *EltPHI << '\n'); 777f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)] = EltPHI; 778f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 77903fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 780f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Replace the use of this piece with the PHI node. 781f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ReplaceInstUsesWith(*PHIUsers[UserI].Inst, EltPHI); 782f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 78303fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 784f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Replace all the remaining uses of the PHI nodes (self uses and the lshrs) 785f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // with undefs. 786f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *Undef = UndefValue::get(FirstPhi.getType()); 787f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i) 788f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ReplaceInstUsesWith(*PHIsToSlice[i], Undef); 789f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return ReplaceInstUsesWith(FirstPhi, Undef); 790f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner} 791f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 792f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// PHINode simplification 793f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner// 794f54e72962991005a3c0cc7dce0c550a14af90792Chris LattnerInstruction *InstCombiner::visitPHINode(PHINode &PN) { 795cd6636c737a82949ad13db2d0d918af6424fb78bDuncan Sands if (Value *V = SimplifyInstruction(&PN, TD)) 796f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return ReplaceInstUsesWith(PN, V); 797f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 798f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If all PHI operands are the same operation, pull them through the PHI, 799f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // reducing code size. 800f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (isa<Instruction>(PN.getIncomingValue(0)) && 801f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner isa<Instruction>(PN.getIncomingValue(1)) && 802f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner cast<Instruction>(PN.getIncomingValue(0))->getOpcode() == 803f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner cast<Instruction>(PN.getIncomingValue(1))->getOpcode() && 804f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // FIXME: The hasOneUse check will fail for PHIs that use the value more 805f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // than themselves more than once. 806f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.getIncomingValue(0)->hasOneUse()) 807f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (Instruction *Result = FoldPHIArgOpIntoPHI(PN)) 808f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return Result; 809f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 810f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If this is a trivial cycle in the PHI node graph, remove it. Basically, if 811f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // this PHI only has a single use (a PHI), and if that PHI only has one use (a 812f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // PHI)... break the cycle. 813f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PN.hasOneUse()) { 814f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Instruction *PHIUser = cast<Instruction>(PN.use_back()); 815f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) { 816f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs; 817f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PotentiallyDeadPHIs.insert(&PN); 818f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (DeadPHICycle(PU, PotentiallyDeadPHIs)) 819f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType())); 820f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 82103fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 822f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If this phi has a single use, and if that use just computes a value for 823f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the next iteration of a loop, delete the phi. This occurs with unused 824f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // induction variables, e.g. "for (int j = 0; ; ++j);". Detecting this 825f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // common case here is good because the only other things that catch this 826f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // are induction variable analysis (sometimes) and ADCE, which is only run 827f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // late. 828f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIUser->hasOneUse() && 829f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) && 830f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHIUser->use_back() == &PN) { 831f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType())); 832f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 833f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 834f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 835f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // We sometimes end up with phi cycles that non-obviously end up being the 836f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // same value, for example: 837f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // z = some value; x = phi (y, z); y = phi (x, z) 838f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // where the phi nodes don't necessarily need to be in the same block. Do a 839f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // quick check to see if the PHI node only contains a single non-phi value, if 840f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // so, scan to see if the phi cycle is actually equal to that value. 841f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner { 84286f72a8002ef6049d17ae8b9a536dee18b101fd0Frits van Bommel unsigned InValNo = 0, NumIncomingVals = PN.getNumIncomingValues(); 843f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Scan for the first non-phi operand. 84486f72a8002ef6049d17ae8b9a536dee18b101fd0Frits van Bommel while (InValNo != NumIncomingVals && 845f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner isa<PHINode>(PN.getIncomingValue(InValNo))) 846f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner ++InValNo; 847f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 84886f72a8002ef6049d17ae8b9a536dee18b101fd0Frits van Bommel if (InValNo != NumIncomingVals) { 8494130278fbee97b9cd1ea4069e9c666bbe89d61f9Jay Foad Value *NonPhiInVal = PN.getIncomingValue(InValNo); 85003fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 851f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // Scan the rest of the operands to see if there are any conflicts, if so 852f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // there is no need to recursively scan other phis. 85386f72a8002ef6049d17ae8b9a536dee18b101fd0Frits van Bommel for (++InValNo; InValNo != NumIncomingVals; ++InValNo) { 854f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *OpVal = PN.getIncomingValue(InValNo); 855f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal)) 856f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner break; 857f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 85803fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 859f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If we scanned over all operands, then we have one unique value plus 860f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // phi values. Scan PHI nodes to see if they all merge in each other or 861f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the value. 86286f72a8002ef6049d17ae8b9a536dee18b101fd0Frits van Bommel if (InValNo == NumIncomingVals) { 863f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner SmallPtrSet<PHINode*, 16> ValueEqualPHIs; 864f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs)) 865f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return ReplaceInstUsesWith(PN, NonPhiInVal); 866f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 867f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 868f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 869f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 870f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If there are multiple PHIs, sort their operands so that they all list 871f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // the blocks in the same order. This will help identical PHIs be eliminated 872f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // by other passes. Other passes shouldn't depend on this for correctness 873f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // however. 874f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PHINode *FirstPN = cast<PHINode>(PN.getParent()->begin()); 875f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (&PN != FirstPN) 876f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner for (unsigned i = 0, e = FirstPN->getNumIncomingValues(); i != e; ++i) { 877f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner BasicBlock *BBA = PN.getIncomingBlock(i); 878f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner BasicBlock *BBB = FirstPN->getIncomingBlock(i); 879f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (BBA != BBB) { 880f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *VA = PN.getIncomingValue(i); 881f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner unsigned j = PN.getBasicBlockIndex(BBB); 882f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner Value *VB = PN.getIncomingValue(j); 883f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.setIncomingBlock(i, BBB); 884f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.setIncomingValue(i, VB); 885f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.setIncomingBlock(j, BBA); 886f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner PN.setIncomingValue(j, VA); 887f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // NOTE: Instcombine normally would want us to "return &PN" if we 888f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // modified any of the operands of an instruction. However, since we 889f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // aren't adding or removing uses (just rearranging them) we don't do 890f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // this in this case. 891f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 892f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner } 893f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner 894f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // If this is an integer PHI and we know that it has an illegal type, see if 895f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // it is only used by trunc or trunc(lshr) operations. If so, we split the 896f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // PHI into the various pieces being extracted. This sort of thing is 897f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner // introduced when SROA promotes an aggregate to a single large integer type. 8981df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (PN.getType()->isIntegerTy() && TD && 899f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner !TD->isLegalInteger(PN.getType()->getPrimitiveSizeInBits())) 900f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner if (Instruction *Res = SliceUpIllegalIntegerPHI(PN)) 901f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return Res; 90203fceff6f69a0261a767aab8e62de8aa9301b86cJim Grosbach 903f54e72962991005a3c0cc7dce0c550a14af90792Chris Lattner return 0; 904eade00209447c07953a609b30666ce5f6d9f9864Benjamin Kramer} 905