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https://github.com/c64scene-ar/llvm-6502.git
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fe58be3733
An icmp may have pointer arguments, it isn't limited to integers or vectors of integers. This fixes PR21388. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220664 91177308-0d34-0410-b5e6-96231b3b80d8
1906 lines
78 KiB
C++
1906 lines
78 KiB
C++
//===- InstCombineCasts.cpp -----------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the visit functions for cast operations.
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//
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//===----------------------------------------------------------------------===//
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#include "InstCombine.h"
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#include "llvm/Analysis/ConstantFolding.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/PatternMatch.h"
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#include "llvm/Target/TargetLibraryInfo.h"
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using namespace llvm;
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using namespace PatternMatch;
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#define DEBUG_TYPE "instcombine"
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/// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
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/// expression. If so, decompose it, returning some value X, such that Val is
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/// X*Scale+Offset.
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///
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static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
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uint64_t &Offset) {
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if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
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Offset = CI->getZExtValue();
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Scale = 0;
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return ConstantInt::get(Val->getType(), 0);
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}
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if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
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// Cannot look past anything that might overflow.
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OverflowingBinaryOperator *OBI = dyn_cast<OverflowingBinaryOperator>(Val);
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if (OBI && !OBI->hasNoUnsignedWrap() && !OBI->hasNoSignedWrap()) {
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Scale = 1;
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Offset = 0;
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return Val;
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}
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if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
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if (I->getOpcode() == Instruction::Shl) {
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// This is a value scaled by '1 << the shift amt'.
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Scale = UINT64_C(1) << RHS->getZExtValue();
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Offset = 0;
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return I->getOperand(0);
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}
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if (I->getOpcode() == Instruction::Mul) {
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// This value is scaled by 'RHS'.
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Scale = RHS->getZExtValue();
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Offset = 0;
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return I->getOperand(0);
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}
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if (I->getOpcode() == Instruction::Add) {
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// We have X+C. Check to see if we really have (X*C2)+C1,
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// where C1 is divisible by C2.
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unsigned SubScale;
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Value *SubVal =
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DecomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
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Offset += RHS->getZExtValue();
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Scale = SubScale;
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return SubVal;
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}
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}
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}
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// Otherwise, we can't look past this.
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Scale = 1;
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Offset = 0;
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return Val;
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}
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/// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
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/// try to eliminate the cast by moving the type information into the alloc.
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Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
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AllocaInst &AI) {
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// This requires DataLayout to get the alloca alignment and size information.
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if (!DL) return nullptr;
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PointerType *PTy = cast<PointerType>(CI.getType());
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BuilderTy AllocaBuilder(*Builder);
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AllocaBuilder.SetInsertPoint(AI.getParent(), &AI);
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// Get the type really allocated and the type casted to.
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Type *AllocElTy = AI.getAllocatedType();
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Type *CastElTy = PTy->getElementType();
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if (!AllocElTy->isSized() || !CastElTy->isSized()) return nullptr;
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unsigned AllocElTyAlign = DL->getABITypeAlignment(AllocElTy);
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unsigned CastElTyAlign = DL->getABITypeAlignment(CastElTy);
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if (CastElTyAlign < AllocElTyAlign) return nullptr;
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// If the allocation has multiple uses, only promote it if we are strictly
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// increasing the alignment of the resultant allocation. If we keep it the
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// same, we open the door to infinite loops of various kinds.
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if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return nullptr;
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uint64_t AllocElTySize = DL->getTypeAllocSize(AllocElTy);
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uint64_t CastElTySize = DL->getTypeAllocSize(CastElTy);
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if (CastElTySize == 0 || AllocElTySize == 0) return nullptr;
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// If the allocation has multiple uses, only promote it if we're not
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// shrinking the amount of memory being allocated.
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uint64_t AllocElTyStoreSize = DL->getTypeStoreSize(AllocElTy);
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uint64_t CastElTyStoreSize = DL->getTypeStoreSize(CastElTy);
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if (!AI.hasOneUse() && CastElTyStoreSize < AllocElTyStoreSize) return nullptr;
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// See if we can satisfy the modulus by pulling a scale out of the array
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// size argument.
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unsigned ArraySizeScale;
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uint64_t ArrayOffset;
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Value *NumElements = // See if the array size is a decomposable linear expr.
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DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
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// If we can now satisfy the modulus, by using a non-1 scale, we really can
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// do the xform.
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if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
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(AllocElTySize*ArrayOffset ) % CastElTySize != 0) return nullptr;
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unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
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Value *Amt = nullptr;
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if (Scale == 1) {
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Amt = NumElements;
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} else {
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Amt = ConstantInt::get(AI.getArraySize()->getType(), Scale);
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// Insert before the alloca, not before the cast.
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Amt = AllocaBuilder.CreateMul(Amt, NumElements);
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}
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if (uint64_t Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
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Value *Off = ConstantInt::get(AI.getArraySize()->getType(),
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Offset, true);
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Amt = AllocaBuilder.CreateAdd(Amt, Off);
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}
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AllocaInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt);
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New->setAlignment(AI.getAlignment());
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New->takeName(&AI);
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New->setUsedWithInAlloca(AI.isUsedWithInAlloca());
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// If the allocation has multiple real uses, insert a cast and change all
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// things that used it to use the new cast. This will also hack on CI, but it
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// will die soon.
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if (!AI.hasOneUse()) {
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// New is the allocation instruction, pointer typed. AI is the original
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// allocation instruction, also pointer typed. Thus, cast to use is BitCast.
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Value *NewCast = AllocaBuilder.CreateBitCast(New, AI.getType(), "tmpcast");
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ReplaceInstUsesWith(AI, NewCast);
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}
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return ReplaceInstUsesWith(CI, New);
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}
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/// EvaluateInDifferentType - Given an expression that
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/// CanEvaluateTruncated or CanEvaluateSExtd returns true for, actually
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/// insert the code to evaluate the expression.
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Value *InstCombiner::EvaluateInDifferentType(Value *V, Type *Ty,
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bool isSigned) {
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if (Constant *C = dyn_cast<Constant>(V)) {
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C = ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
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// If we got a constantexpr back, try to simplify it with DL info.
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if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
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C = ConstantFoldConstantExpression(CE, DL, TLI);
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return C;
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}
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// Otherwise, it must be an instruction.
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Instruction *I = cast<Instruction>(V);
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Instruction *Res = nullptr;
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unsigned Opc = I->getOpcode();
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switch (Opc) {
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case Instruction::Add:
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case Instruction::Sub:
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case Instruction::Mul:
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case Instruction::And:
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case Instruction::Or:
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case Instruction::Xor:
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case Instruction::AShr:
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case Instruction::LShr:
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case Instruction::Shl:
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case Instruction::UDiv:
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case Instruction::URem: {
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Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
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Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
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Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
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break;
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}
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case Instruction::Trunc:
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case Instruction::ZExt:
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case Instruction::SExt:
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// If the source type of the cast is the type we're trying for then we can
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// just return the source. There's no need to insert it because it is not
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// new.
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if (I->getOperand(0)->getType() == Ty)
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return I->getOperand(0);
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// Otherwise, must be the same type of cast, so just reinsert a new one.
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// This also handles the case of zext(trunc(x)) -> zext(x).
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Res = CastInst::CreateIntegerCast(I->getOperand(0), Ty,
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Opc == Instruction::SExt);
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break;
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case Instruction::Select: {
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Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
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Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
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Res = SelectInst::Create(I->getOperand(0), True, False);
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break;
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}
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case Instruction::PHI: {
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PHINode *OPN = cast<PHINode>(I);
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PHINode *NPN = PHINode::Create(Ty, OPN->getNumIncomingValues());
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for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
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Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
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NPN->addIncoming(V, OPN->getIncomingBlock(i));
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}
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Res = NPN;
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break;
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}
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default:
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// TODO: Can handle more cases here.
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llvm_unreachable("Unreachable!");
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}
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Res->takeName(I);
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return InsertNewInstWith(Res, *I);
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}
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/// This function is a wrapper around CastInst::isEliminableCastPair. It
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/// simply extracts arguments and returns what that function returns.
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static Instruction::CastOps
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isEliminableCastPair(
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const CastInst *CI, ///< The first cast instruction
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unsigned opcode, ///< The opcode of the second cast instruction
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Type *DstTy, ///< The target type for the second cast instruction
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const DataLayout *DL ///< The target data for pointer size
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) {
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Type *SrcTy = CI->getOperand(0)->getType(); // A from above
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Type *MidTy = CI->getType(); // B from above
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// Get the opcodes of the two Cast instructions
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Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
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Instruction::CastOps secondOp = Instruction::CastOps(opcode);
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Type *SrcIntPtrTy = DL && SrcTy->isPtrOrPtrVectorTy() ?
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DL->getIntPtrType(SrcTy) : nullptr;
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Type *MidIntPtrTy = DL && MidTy->isPtrOrPtrVectorTy() ?
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DL->getIntPtrType(MidTy) : nullptr;
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Type *DstIntPtrTy = DL && DstTy->isPtrOrPtrVectorTy() ?
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DL->getIntPtrType(DstTy) : nullptr;
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unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
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DstTy, SrcIntPtrTy, MidIntPtrTy,
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DstIntPtrTy);
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// We don't want to form an inttoptr or ptrtoint that converts to an integer
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// type that differs from the pointer size.
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if ((Res == Instruction::IntToPtr && SrcTy != DstIntPtrTy) ||
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(Res == Instruction::PtrToInt && DstTy != SrcIntPtrTy))
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Res = 0;
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return Instruction::CastOps(Res);
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}
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/// ShouldOptimizeCast - Return true if the cast from "V to Ty" actually
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/// results in any code being generated and is interesting to optimize out. If
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/// the cast can be eliminated by some other simple transformation, we prefer
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/// to do the simplification first.
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bool InstCombiner::ShouldOptimizeCast(Instruction::CastOps opc, const Value *V,
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Type *Ty) {
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// Noop casts and casts of constants should be eliminated trivially.
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if (V->getType() == Ty || isa<Constant>(V)) return false;
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// If this is another cast that can be eliminated, we prefer to have it
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// eliminated.
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if (const CastInst *CI = dyn_cast<CastInst>(V))
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if (isEliminableCastPair(CI, opc, Ty, DL))
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return false;
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// If this is a vector sext from a compare, then we don't want to break the
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// idiom where each element of the extended vector is either zero or all ones.
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if (opc == Instruction::SExt && isa<CmpInst>(V) && Ty->isVectorTy())
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return false;
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return true;
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}
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/// @brief Implement the transforms common to all CastInst visitors.
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Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
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Value *Src = CI.getOperand(0);
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// Many cases of "cast of a cast" are eliminable. If it's eliminable we just
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// eliminate it now.
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if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
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if (Instruction::CastOps opc =
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isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), DL)) {
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// The first cast (CSrc) is eliminable so we need to fix up or replace
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// the second cast (CI). CSrc will then have a good chance of being dead.
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return CastInst::Create(opc, CSrc->getOperand(0), CI.getType());
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}
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}
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// If we are casting a select then fold the cast into the select
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if (SelectInst *SI = dyn_cast<SelectInst>(Src))
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if (Instruction *NV = FoldOpIntoSelect(CI, SI))
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return NV;
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// If we are casting a PHI then fold the cast into the PHI
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if (isa<PHINode>(Src)) {
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// We don't do this if this would create a PHI node with an illegal type if
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// it is currently legal.
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if (!Src->getType()->isIntegerTy() ||
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!CI.getType()->isIntegerTy() ||
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ShouldChangeType(CI.getType(), Src->getType()))
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if (Instruction *NV = FoldOpIntoPhi(CI))
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return NV;
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}
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return nullptr;
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}
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/// CanEvaluateTruncated - Return true if we can evaluate the specified
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/// expression tree as type Ty instead of its larger type, and arrive with the
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/// same value. This is used by code that tries to eliminate truncates.
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///
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/// Ty will always be a type smaller than V. We should return true if trunc(V)
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/// can be computed by computing V in the smaller type. If V is an instruction,
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/// then trunc(inst(x,y)) can be computed as inst(trunc(x),trunc(y)), which only
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/// makes sense if x and y can be efficiently truncated.
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///
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/// This function works on both vectors and scalars.
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///
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static bool CanEvaluateTruncated(Value *V, Type *Ty, InstCombiner &IC,
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Instruction *CxtI) {
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// We can always evaluate constants in another type.
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if (isa<Constant>(V))
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return true;
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Instruction *I = dyn_cast<Instruction>(V);
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if (!I) return false;
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Type *OrigTy = V->getType();
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// If this is an extension from the dest type, we can eliminate it, even if it
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// has multiple uses.
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if ((isa<ZExtInst>(I) || isa<SExtInst>(I)) &&
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I->getOperand(0)->getType() == Ty)
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return true;
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// We can't extend or shrink something that has multiple uses: doing so would
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// require duplicating the instruction in general, which isn't profitable.
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if (!I->hasOneUse()) return false;
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unsigned Opc = I->getOpcode();
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switch (Opc) {
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case Instruction::Add:
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case Instruction::Sub:
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case Instruction::Mul:
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case Instruction::And:
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case Instruction::Or:
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case Instruction::Xor:
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// These operators can all arbitrarily be extended or truncated.
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return CanEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) &&
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CanEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI);
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case Instruction::UDiv:
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case Instruction::URem: {
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// UDiv and URem can be truncated if all the truncated bits are zero.
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uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
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uint32_t BitWidth = Ty->getScalarSizeInBits();
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if (BitWidth < OrigBitWidth) {
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APInt Mask = APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth);
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if (IC.MaskedValueIsZero(I->getOperand(0), Mask, 0, CxtI) &&
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IC.MaskedValueIsZero(I->getOperand(1), Mask, 0, CxtI)) {
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return CanEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) &&
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CanEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI);
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}
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}
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break;
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}
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case Instruction::Shl:
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// If we are truncating the result of this SHL, and if it's a shift of a
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// constant amount, we can always perform a SHL in a smaller type.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
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uint32_t BitWidth = Ty->getScalarSizeInBits();
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if (CI->getLimitedValue(BitWidth) < BitWidth)
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return CanEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI);
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}
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break;
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case Instruction::LShr:
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// If this is a truncate of a logical shr, we can truncate it to a smaller
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// lshr iff we know that the bits we would otherwise be shifting in are
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// already zeros.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
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uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
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uint32_t BitWidth = Ty->getScalarSizeInBits();
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if (IC.MaskedValueIsZero(I->getOperand(0),
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APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth), 0, CxtI) &&
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CI->getLimitedValue(BitWidth) < BitWidth) {
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return CanEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI);
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}
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}
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break;
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case Instruction::Trunc:
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// trunc(trunc(x)) -> trunc(x)
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return true;
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case Instruction::ZExt:
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case Instruction::SExt:
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// trunc(ext(x)) -> ext(x) if the source type is smaller than the new dest
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// trunc(ext(x)) -> trunc(x) if the source type is larger than the new dest
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return true;
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case Instruction::Select: {
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SelectInst *SI = cast<SelectInst>(I);
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return CanEvaluateTruncated(SI->getTrueValue(), Ty, IC, CxtI) &&
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CanEvaluateTruncated(SI->getFalseValue(), Ty, IC, CxtI);
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}
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case Instruction::PHI: {
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// We can change a phi if we can change all operands. Note that we never
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// get into trouble with cyclic PHIs here because we only consider
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// instructions with a single use.
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PHINode *PN = cast<PHINode>(I);
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for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
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if (!CanEvaluateTruncated(PN->getIncomingValue(i), Ty, IC, CxtI))
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return false;
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return true;
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}
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default:
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// TODO: Can handle more cases here.
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break;
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}
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return false;
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}
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Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
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if (Instruction *Result = commonCastTransforms(CI))
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return Result;
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// See if we can simplify any instructions used by the input whose sole
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// purpose is to compute bits we don't care about.
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if (SimplifyDemandedInstructionBits(CI))
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|
return &CI;
|
|
|
|
Value *Src = CI.getOperand(0);
|
|
Type *DestTy = CI.getType(), *SrcTy = Src->getType();
|
|
|
|
// Attempt to truncate the entire input expression tree to the destination
|
|
// type. Only do this if the dest type is a simple type, don't convert the
|
|
// expression tree to something weird like i93 unless the source is also
|
|
// strange.
|
|
if ((DestTy->isVectorTy() || ShouldChangeType(SrcTy, DestTy)) &&
|
|
CanEvaluateTruncated(Src, DestTy, *this, &CI)) {
|
|
|
|
// If this cast is a truncate, evaluting in a different type always
|
|
// eliminates the cast, so it is always a win.
|
|
DEBUG(dbgs() << "ICE: EvaluateInDifferentType converting expression type"
|
|
" to avoid cast: " << CI << '\n');
|
|
Value *Res = EvaluateInDifferentType(Src, DestTy, false);
|
|
assert(Res->getType() == DestTy);
|
|
return ReplaceInstUsesWith(CI, Res);
|
|
}
|
|
|
|
// Canonicalize trunc x to i1 -> (icmp ne (and x, 1), 0), likewise for vector.
|
|
if (DestTy->getScalarSizeInBits() == 1) {
|
|
Constant *One = ConstantInt::get(Src->getType(), 1);
|
|
Src = Builder->CreateAnd(Src, One);
|
|
Value *Zero = Constant::getNullValue(Src->getType());
|
|
return new ICmpInst(ICmpInst::ICMP_NE, Src, Zero);
|
|
}
|
|
|
|
// Transform trunc(lshr (zext A), Cst) to eliminate one type conversion.
|
|
Value *A = nullptr; ConstantInt *Cst = nullptr;
|
|
if (Src->hasOneUse() &&
|
|
match(Src, m_LShr(m_ZExt(m_Value(A)), m_ConstantInt(Cst)))) {
|
|
// We have three types to worry about here, the type of A, the source of
|
|
// the truncate (MidSize), and the destination of the truncate. We know that
|
|
// ASize < MidSize and MidSize > ResultSize, but don't know the relation
|
|
// between ASize and ResultSize.
|
|
unsigned ASize = A->getType()->getPrimitiveSizeInBits();
|
|
|
|
// If the shift amount is larger than the size of A, then the result is
|
|
// known to be zero because all the input bits got shifted out.
|
|
if (Cst->getZExtValue() >= ASize)
|
|
return ReplaceInstUsesWith(CI, Constant::getNullValue(CI.getType()));
|
|
|
|
// Since we're doing an lshr and a zero extend, and know that the shift
|
|
// amount is smaller than ASize, it is always safe to do the shift in A's
|
|
// type, then zero extend or truncate to the result.
|
|
Value *Shift = Builder->CreateLShr(A, Cst->getZExtValue());
|
|
Shift->takeName(Src);
|
|
return CastInst::CreateIntegerCast(Shift, CI.getType(), false);
|
|
}
|
|
|
|
// Transform "trunc (and X, cst)" -> "and (trunc X), cst" so long as the dest
|
|
// type isn't non-native.
|
|
if (Src->hasOneUse() && isa<IntegerType>(Src->getType()) &&
|
|
ShouldChangeType(Src->getType(), CI.getType()) &&
|
|
match(Src, m_And(m_Value(A), m_ConstantInt(Cst)))) {
|
|
Value *NewTrunc = Builder->CreateTrunc(A, CI.getType(), A->getName()+".tr");
|
|
return BinaryOperator::CreateAnd(NewTrunc,
|
|
ConstantExpr::getTrunc(Cst, CI.getType()));
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// transformZExtICmp - Transform (zext icmp) to bitwise / integer operations
|
|
/// in order to eliminate the icmp.
|
|
Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI,
|
|
bool DoXform) {
|
|
// If we are just checking for a icmp eq of a single bit and zext'ing it
|
|
// to an integer, then shift the bit to the appropriate place and then
|
|
// cast to integer to avoid the comparison.
|
|
if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
|
|
const APInt &Op1CV = Op1C->getValue();
|
|
|
|
// zext (x <s 0) to i32 --> x>>u31 true if signbit set.
|
|
// zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
|
|
if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
|
|
(ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) {
|
|
if (!DoXform) return ICI;
|
|
|
|
Value *In = ICI->getOperand(0);
|
|
Value *Sh = ConstantInt::get(In->getType(),
|
|
In->getType()->getScalarSizeInBits()-1);
|
|
In = Builder->CreateLShr(In, Sh, In->getName()+".lobit");
|
|
if (In->getType() != CI.getType())
|
|
In = Builder->CreateIntCast(In, CI.getType(), false/*ZExt*/);
|
|
|
|
if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
|
|
Constant *One = ConstantInt::get(In->getType(), 1);
|
|
In = Builder->CreateXor(In, One, In->getName()+".not");
|
|
}
|
|
|
|
return ReplaceInstUsesWith(CI, In);
|
|
}
|
|
|
|
// zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
|
|
// zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
|
|
// zext (X == 1) to i32 --> X iff X has only the low bit set.
|
|
// zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
|
|
// zext (X != 0) to i32 --> X iff X has only the low bit set.
|
|
// zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
|
|
// zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
|
|
// zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
|
|
if ((Op1CV == 0 || Op1CV.isPowerOf2()) &&
|
|
// This only works for EQ and NE
|
|
ICI->isEquality()) {
|
|
// If Op1C some other power of two, convert:
|
|
uint32_t BitWidth = Op1C->getType()->getBitWidth();
|
|
APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
|
|
computeKnownBits(ICI->getOperand(0), KnownZero, KnownOne, 0, &CI);
|
|
|
|
APInt KnownZeroMask(~KnownZero);
|
|
if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
|
|
if (!DoXform) return ICI;
|
|
|
|
bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
|
|
if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
|
|
// (X&4) == 2 --> false
|
|
// (X&4) != 2 --> true
|
|
Constant *Res = ConstantInt::get(Type::getInt1Ty(CI.getContext()),
|
|
isNE);
|
|
Res = ConstantExpr::getZExt(Res, CI.getType());
|
|
return ReplaceInstUsesWith(CI, Res);
|
|
}
|
|
|
|
uint32_t ShiftAmt = KnownZeroMask.logBase2();
|
|
Value *In = ICI->getOperand(0);
|
|
if (ShiftAmt) {
|
|
// Perform a logical shr by shiftamt.
|
|
// Insert the shift to put the result in the low bit.
|
|
In = Builder->CreateLShr(In, ConstantInt::get(In->getType(),ShiftAmt),
|
|
In->getName()+".lobit");
|
|
}
|
|
|
|
if ((Op1CV != 0) == isNE) { // Toggle the low bit.
|
|
Constant *One = ConstantInt::get(In->getType(), 1);
|
|
In = Builder->CreateXor(In, One);
|
|
}
|
|
|
|
if (CI.getType() == In->getType())
|
|
return ReplaceInstUsesWith(CI, In);
|
|
return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/);
|
|
}
|
|
}
|
|
}
|
|
|
|
// icmp ne A, B is equal to xor A, B when A and B only really have one bit.
|
|
// It is also profitable to transform icmp eq into not(xor(A, B)) because that
|
|
// may lead to additional simplifications.
|
|
if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) {
|
|
if (IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) {
|
|
uint32_t BitWidth = ITy->getBitWidth();
|
|
Value *LHS = ICI->getOperand(0);
|
|
Value *RHS = ICI->getOperand(1);
|
|
|
|
APInt KnownZeroLHS(BitWidth, 0), KnownOneLHS(BitWidth, 0);
|
|
APInt KnownZeroRHS(BitWidth, 0), KnownOneRHS(BitWidth, 0);
|
|
computeKnownBits(LHS, KnownZeroLHS, KnownOneLHS, 0, &CI);
|
|
computeKnownBits(RHS, KnownZeroRHS, KnownOneRHS, 0, &CI);
|
|
|
|
if (KnownZeroLHS == KnownZeroRHS && KnownOneLHS == KnownOneRHS) {
|
|
APInt KnownBits = KnownZeroLHS | KnownOneLHS;
|
|
APInt UnknownBit = ~KnownBits;
|
|
if (UnknownBit.countPopulation() == 1) {
|
|
if (!DoXform) return ICI;
|
|
|
|
Value *Result = Builder->CreateXor(LHS, RHS);
|
|
|
|
// Mask off any bits that are set and won't be shifted away.
|
|
if (KnownOneLHS.uge(UnknownBit))
|
|
Result = Builder->CreateAnd(Result,
|
|
ConstantInt::get(ITy, UnknownBit));
|
|
|
|
// Shift the bit we're testing down to the lsb.
|
|
Result = Builder->CreateLShr(
|
|
Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros()));
|
|
|
|
if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
|
|
Result = Builder->CreateXor(Result, ConstantInt::get(ITy, 1));
|
|
Result->takeName(ICI);
|
|
return ReplaceInstUsesWith(CI, Result);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// CanEvaluateZExtd - Determine if the specified value can be computed in the
|
|
/// specified wider type and produce the same low bits. If not, return false.
|
|
///
|
|
/// If this function returns true, it can also return a non-zero number of bits
|
|
/// (in BitsToClear) which indicates that the value it computes is correct for
|
|
/// the zero extend, but that the additional BitsToClear bits need to be zero'd
|
|
/// out. For example, to promote something like:
|
|
///
|
|
/// %B = trunc i64 %A to i32
|
|
/// %C = lshr i32 %B, 8
|
|
/// %E = zext i32 %C to i64
|
|
///
|
|
/// CanEvaluateZExtd for the 'lshr' will return true, and BitsToClear will be
|
|
/// set to 8 to indicate that the promoted value needs to have bits 24-31
|
|
/// cleared in addition to bits 32-63. Since an 'and' will be generated to
|
|
/// clear the top bits anyway, doing this has no extra cost.
|
|
///
|
|
/// This function works on both vectors and scalars.
|
|
static bool CanEvaluateZExtd(Value *V, Type *Ty, unsigned &BitsToClear,
|
|
InstCombiner &IC, Instruction *CxtI) {
|
|
BitsToClear = 0;
|
|
if (isa<Constant>(V))
|
|
return true;
|
|
|
|
Instruction *I = dyn_cast<Instruction>(V);
|
|
if (!I) return false;
|
|
|
|
// If the input is a truncate from the destination type, we can trivially
|
|
// eliminate it.
|
|
if (isa<TruncInst>(I) && I->getOperand(0)->getType() == Ty)
|
|
return true;
|
|
|
|
// We can't extend or shrink something that has multiple uses: doing so would
|
|
// require duplicating the instruction in general, which isn't profitable.
|
|
if (!I->hasOneUse()) return false;
|
|
|
|
unsigned Opc = I->getOpcode(), Tmp;
|
|
switch (Opc) {
|
|
case Instruction::ZExt: // zext(zext(x)) -> zext(x).
|
|
case Instruction::SExt: // zext(sext(x)) -> sext(x).
|
|
case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x)
|
|
return true;
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
case Instruction::Add:
|
|
case Instruction::Sub:
|
|
case Instruction::Mul:
|
|
if (!CanEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI) ||
|
|
!CanEvaluateZExtd(I->getOperand(1), Ty, Tmp, IC, CxtI))
|
|
return false;
|
|
// These can all be promoted if neither operand has 'bits to clear'.
|
|
if (BitsToClear == 0 && Tmp == 0)
|
|
return true;
|
|
|
|
// If the operation is an AND/OR/XOR and the bits to clear are zero in the
|
|
// other side, BitsToClear is ok.
|
|
if (Tmp == 0 &&
|
|
(Opc == Instruction::And || Opc == Instruction::Or ||
|
|
Opc == Instruction::Xor)) {
|
|
// We use MaskedValueIsZero here for generality, but the case we care
|
|
// about the most is constant RHS.
|
|
unsigned VSize = V->getType()->getScalarSizeInBits();
|
|
if (IC.MaskedValueIsZero(I->getOperand(1),
|
|
APInt::getHighBitsSet(VSize, BitsToClear),
|
|
0, CxtI))
|
|
return true;
|
|
}
|
|
|
|
// Otherwise, we don't know how to analyze this BitsToClear case yet.
|
|
return false;
|
|
|
|
case Instruction::Shl:
|
|
// We can promote shl(x, cst) if we can promote x. Since shl overwrites the
|
|
// upper bits we can reduce BitsToClear by the shift amount.
|
|
if (ConstantInt *Amt = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
|
if (!CanEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI))
|
|
return false;
|
|
uint64_t ShiftAmt = Amt->getZExtValue();
|
|
BitsToClear = ShiftAmt < BitsToClear ? BitsToClear - ShiftAmt : 0;
|
|
return true;
|
|
}
|
|
return false;
|
|
case Instruction::LShr:
|
|
// We can promote lshr(x, cst) if we can promote x. This requires the
|
|
// ultimate 'and' to clear out the high zero bits we're clearing out though.
|
|
if (ConstantInt *Amt = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
|
if (!CanEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI))
|
|
return false;
|
|
BitsToClear += Amt->getZExtValue();
|
|
if (BitsToClear > V->getType()->getScalarSizeInBits())
|
|
BitsToClear = V->getType()->getScalarSizeInBits();
|
|
return true;
|
|
}
|
|
// Cannot promote variable LSHR.
|
|
return false;
|
|
case Instruction::Select:
|
|
if (!CanEvaluateZExtd(I->getOperand(1), Ty, Tmp, IC, CxtI) ||
|
|
!CanEvaluateZExtd(I->getOperand(2), Ty, BitsToClear, IC, CxtI) ||
|
|
// TODO: If important, we could handle the case when the BitsToClear are
|
|
// known zero in the disagreeing side.
|
|
Tmp != BitsToClear)
|
|
return false;
|
|
return true;
|
|
|
|
case Instruction::PHI: {
|
|
// We can change a phi if we can change all operands. Note that we never
|
|
// get into trouble with cyclic PHIs here because we only consider
|
|
// instructions with a single use.
|
|
PHINode *PN = cast<PHINode>(I);
|
|
if (!CanEvaluateZExtd(PN->getIncomingValue(0), Ty, BitsToClear, IC, CxtI))
|
|
return false;
|
|
for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
|
|
if (!CanEvaluateZExtd(PN->getIncomingValue(i), Ty, Tmp, IC, CxtI) ||
|
|
// TODO: If important, we could handle the case when the BitsToClear
|
|
// are known zero in the disagreeing input.
|
|
Tmp != BitsToClear)
|
|
return false;
|
|
return true;
|
|
}
|
|
default:
|
|
// TODO: Can handle more cases here.
|
|
return false;
|
|
}
|
|
}
|
|
|
|
Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
|
|
// If this zero extend is only used by a truncate, let the truncate be
|
|
// eliminated before we try to optimize this zext.
|
|
if (CI.hasOneUse() && isa<TruncInst>(CI.user_back()))
|
|
return nullptr;
|
|
|
|
// If one of the common conversion will work, do it.
|
|
if (Instruction *Result = commonCastTransforms(CI))
|
|
return Result;
|
|
|
|
// See if we can simplify any instructions used by the input whose sole
|
|
// purpose is to compute bits we don't care about.
|
|
if (SimplifyDemandedInstructionBits(CI))
|
|
return &CI;
|
|
|
|
Value *Src = CI.getOperand(0);
|
|
Type *SrcTy = Src->getType(), *DestTy = CI.getType();
|
|
|
|
// Attempt to extend the entire input expression tree to the destination
|
|
// type. Only do this if the dest type is a simple type, don't convert the
|
|
// expression tree to something weird like i93 unless the source is also
|
|
// strange.
|
|
unsigned BitsToClear;
|
|
if ((DestTy->isVectorTy() || ShouldChangeType(SrcTy, DestTy)) &&
|
|
CanEvaluateZExtd(Src, DestTy, BitsToClear, *this, &CI)) {
|
|
assert(BitsToClear < SrcTy->getScalarSizeInBits() &&
|
|
"Unreasonable BitsToClear");
|
|
|
|
// Okay, we can transform this! Insert the new expression now.
|
|
DEBUG(dbgs() << "ICE: EvaluateInDifferentType converting expression type"
|
|
" to avoid zero extend: " << CI);
|
|
Value *Res = EvaluateInDifferentType(Src, DestTy, false);
|
|
assert(Res->getType() == DestTy);
|
|
|
|
uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits()-BitsToClear;
|
|
uint32_t DestBitSize = DestTy->getScalarSizeInBits();
|
|
|
|
// If the high bits are already filled with zeros, just replace this
|
|
// cast with the result.
|
|
if (MaskedValueIsZero(Res,
|
|
APInt::getHighBitsSet(DestBitSize,
|
|
DestBitSize-SrcBitsKept),
|
|
0, &CI))
|
|
return ReplaceInstUsesWith(CI, Res);
|
|
|
|
// We need to emit an AND to clear the high bits.
|
|
Constant *C = ConstantInt::get(Res->getType(),
|
|
APInt::getLowBitsSet(DestBitSize, SrcBitsKept));
|
|
return BinaryOperator::CreateAnd(Res, C);
|
|
}
|
|
|
|
// If this is a TRUNC followed by a ZEXT then we are dealing with integral
|
|
// types and if the sizes are just right we can convert this into a logical
|
|
// 'and' which will be much cheaper than the pair of casts.
|
|
if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast
|
|
// TODO: Subsume this into EvaluateInDifferentType.
|
|
|
|
// Get the sizes of the types involved. We know that the intermediate type
|
|
// will be smaller than A or C, but don't know the relation between A and C.
|
|
Value *A = CSrc->getOperand(0);
|
|
unsigned SrcSize = A->getType()->getScalarSizeInBits();
|
|
unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
|
|
unsigned DstSize = CI.getType()->getScalarSizeInBits();
|
|
// If we're actually extending zero bits, then if
|
|
// SrcSize < DstSize: zext(a & mask)
|
|
// SrcSize == DstSize: a & mask
|
|
// SrcSize > DstSize: trunc(a) & mask
|
|
if (SrcSize < DstSize) {
|
|
APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
|
|
Constant *AndConst = ConstantInt::get(A->getType(), AndValue);
|
|
Value *And = Builder->CreateAnd(A, AndConst, CSrc->getName()+".mask");
|
|
return new ZExtInst(And, CI.getType());
|
|
}
|
|
|
|
if (SrcSize == DstSize) {
|
|
APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
|
|
return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(),
|
|
AndValue));
|
|
}
|
|
if (SrcSize > DstSize) {
|
|
Value *Trunc = Builder->CreateTrunc(A, CI.getType());
|
|
APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
|
|
return BinaryOperator::CreateAnd(Trunc,
|
|
ConstantInt::get(Trunc->getType(),
|
|
AndValue));
|
|
}
|
|
}
|
|
|
|
if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
|
|
return transformZExtICmp(ICI, CI);
|
|
|
|
BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
|
|
if (SrcI && SrcI->getOpcode() == Instruction::Or) {
|
|
// zext (or icmp, icmp) --> or (zext icmp), (zext icmp) if at least one
|
|
// of the (zext icmp) will be transformed.
|
|
ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
|
|
ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
|
|
if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
|
|
(transformZExtICmp(LHS, CI, false) ||
|
|
transformZExtICmp(RHS, CI, false))) {
|
|
Value *LCast = Builder->CreateZExt(LHS, CI.getType(), LHS->getName());
|
|
Value *RCast = Builder->CreateZExt(RHS, CI.getType(), RHS->getName());
|
|
return BinaryOperator::Create(Instruction::Or, LCast, RCast);
|
|
}
|
|
}
|
|
|
|
// zext(trunc(X) & C) -> (X & zext(C)).
|
|
Constant *C;
|
|
Value *X;
|
|
if (SrcI &&
|
|
match(SrcI, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Constant(C)))) &&
|
|
X->getType() == CI.getType())
|
|
return BinaryOperator::CreateAnd(X, ConstantExpr::getZExt(C, CI.getType()));
|
|
|
|
// zext((trunc(X) & C) ^ C) -> ((X & zext(C)) ^ zext(C)).
|
|
Value *And;
|
|
if (SrcI && match(SrcI, m_OneUse(m_Xor(m_Value(And), m_Constant(C)))) &&
|
|
match(And, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Specific(C)))) &&
|
|
X->getType() == CI.getType()) {
|
|
Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
|
|
return BinaryOperator::CreateXor(Builder->CreateAnd(X, ZC), ZC);
|
|
}
|
|
|
|
// zext (xor i1 X, true) to i32 --> xor (zext i1 X to i32), 1
|
|
if (SrcI && SrcI->hasOneUse() &&
|
|
SrcI->getType()->getScalarType()->isIntegerTy(1) &&
|
|
match(SrcI, m_Not(m_Value(X))) && (!X->hasOneUse() || !isa<CmpInst>(X))) {
|
|
Value *New = Builder->CreateZExt(X, CI.getType());
|
|
return BinaryOperator::CreateXor(New, ConstantInt::get(CI.getType(), 1));
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// transformSExtICmp - Transform (sext icmp) to bitwise / integer operations
|
|
/// in order to eliminate the icmp.
|
|
Instruction *InstCombiner::transformSExtICmp(ICmpInst *ICI, Instruction &CI) {
|
|
Value *Op0 = ICI->getOperand(0), *Op1 = ICI->getOperand(1);
|
|
ICmpInst::Predicate Pred = ICI->getPredicate();
|
|
|
|
// Don't bother if Op1 isn't of vector or integer type.
|
|
if (!Op1->getType()->isIntOrIntVectorTy())
|
|
return nullptr;
|
|
|
|
if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
|
|
// (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if negative
|
|
// (x >s -1) ? -1 : 0 -> not (ashr x, 31) -> all ones if positive
|
|
if ((Pred == ICmpInst::ICMP_SLT && Op1C->isNullValue()) ||
|
|
(Pred == ICmpInst::ICMP_SGT && Op1C->isAllOnesValue())) {
|
|
|
|
Value *Sh = ConstantInt::get(Op0->getType(),
|
|
Op0->getType()->getScalarSizeInBits()-1);
|
|
Value *In = Builder->CreateAShr(Op0, Sh, Op0->getName()+".lobit");
|
|
if (In->getType() != CI.getType())
|
|
In = Builder->CreateIntCast(In, CI.getType(), true/*SExt*/);
|
|
|
|
if (Pred == ICmpInst::ICMP_SGT)
|
|
In = Builder->CreateNot(In, In->getName()+".not");
|
|
return ReplaceInstUsesWith(CI, In);
|
|
}
|
|
}
|
|
|
|
if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
|
|
// If we know that only one bit of the LHS of the icmp can be set and we
|
|
// have an equality comparison with zero or a power of 2, we can transform
|
|
// the icmp and sext into bitwise/integer operations.
|
|
if (ICI->hasOneUse() &&
|
|
ICI->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){
|
|
unsigned BitWidth = Op1C->getType()->getBitWidth();
|
|
APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
|
|
computeKnownBits(Op0, KnownZero, KnownOne, 0, &CI);
|
|
|
|
APInt KnownZeroMask(~KnownZero);
|
|
if (KnownZeroMask.isPowerOf2()) {
|
|
Value *In = ICI->getOperand(0);
|
|
|
|
// If the icmp tests for a known zero bit we can constant fold it.
|
|
if (!Op1C->isZero() && Op1C->getValue() != KnownZeroMask) {
|
|
Value *V = Pred == ICmpInst::ICMP_NE ?
|
|
ConstantInt::getAllOnesValue(CI.getType()) :
|
|
ConstantInt::getNullValue(CI.getType());
|
|
return ReplaceInstUsesWith(CI, V);
|
|
}
|
|
|
|
if (!Op1C->isZero() == (Pred == ICmpInst::ICMP_NE)) {
|
|
// sext ((x & 2^n) == 0) -> (x >> n) - 1
|
|
// sext ((x & 2^n) != 2^n) -> (x >> n) - 1
|
|
unsigned ShiftAmt = KnownZeroMask.countTrailingZeros();
|
|
// Perform a right shift to place the desired bit in the LSB.
|
|
if (ShiftAmt)
|
|
In = Builder->CreateLShr(In,
|
|
ConstantInt::get(In->getType(), ShiftAmt));
|
|
|
|
// At this point "In" is either 1 or 0. Subtract 1 to turn
|
|
// {1, 0} -> {0, -1}.
|
|
In = Builder->CreateAdd(In,
|
|
ConstantInt::getAllOnesValue(In->getType()),
|
|
"sext");
|
|
} else {
|
|
// sext ((x & 2^n) != 0) -> (x << bitwidth-n) a>> bitwidth-1
|
|
// sext ((x & 2^n) == 2^n) -> (x << bitwidth-n) a>> bitwidth-1
|
|
unsigned ShiftAmt = KnownZeroMask.countLeadingZeros();
|
|
// Perform a left shift to place the desired bit in the MSB.
|
|
if (ShiftAmt)
|
|
In = Builder->CreateShl(In,
|
|
ConstantInt::get(In->getType(), ShiftAmt));
|
|
|
|
// Distribute the bit over the whole bit width.
|
|
In = Builder->CreateAShr(In, ConstantInt::get(In->getType(),
|
|
BitWidth - 1), "sext");
|
|
}
|
|
|
|
if (CI.getType() == In->getType())
|
|
return ReplaceInstUsesWith(CI, In);
|
|
return CastInst::CreateIntegerCast(In, CI.getType(), true/*SExt*/);
|
|
}
|
|
}
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// CanEvaluateSExtd - Return true if we can take the specified value
|
|
/// and return it as type Ty without inserting any new casts and without
|
|
/// changing the value of the common low bits. This is used by code that tries
|
|
/// to promote integer operations to a wider types will allow us to eliminate
|
|
/// the extension.
|
|
///
|
|
/// This function works on both vectors and scalars.
|
|
///
|
|
static bool CanEvaluateSExtd(Value *V, Type *Ty) {
|
|
assert(V->getType()->getScalarSizeInBits() < Ty->getScalarSizeInBits() &&
|
|
"Can't sign extend type to a smaller type");
|
|
// If this is a constant, it can be trivially promoted.
|
|
if (isa<Constant>(V))
|
|
return true;
|
|
|
|
Instruction *I = dyn_cast<Instruction>(V);
|
|
if (!I) return false;
|
|
|
|
// If this is a truncate from the dest type, we can trivially eliminate it.
|
|
if (isa<TruncInst>(I) && I->getOperand(0)->getType() == Ty)
|
|
return true;
|
|
|
|
// We can't extend or shrink something that has multiple uses: doing so would
|
|
// require duplicating the instruction in general, which isn't profitable.
|
|
if (!I->hasOneUse()) return false;
|
|
|
|
switch (I->getOpcode()) {
|
|
case Instruction::SExt: // sext(sext(x)) -> sext(x)
|
|
case Instruction::ZExt: // sext(zext(x)) -> zext(x)
|
|
case Instruction::Trunc: // sext(trunc(x)) -> trunc(x) or sext(x)
|
|
return true;
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
case Instruction::Add:
|
|
case Instruction::Sub:
|
|
case Instruction::Mul:
|
|
// These operators can all arbitrarily be extended if their inputs can.
|
|
return CanEvaluateSExtd(I->getOperand(0), Ty) &&
|
|
CanEvaluateSExtd(I->getOperand(1), Ty);
|
|
|
|
//case Instruction::Shl: TODO
|
|
//case Instruction::LShr: TODO
|
|
|
|
case Instruction::Select:
|
|
return CanEvaluateSExtd(I->getOperand(1), Ty) &&
|
|
CanEvaluateSExtd(I->getOperand(2), Ty);
|
|
|
|
case Instruction::PHI: {
|
|
// We can change a phi if we can change all operands. Note that we never
|
|
// get into trouble with cyclic PHIs here because we only consider
|
|
// instructions with a single use.
|
|
PHINode *PN = cast<PHINode>(I);
|
|
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
|
|
if (!CanEvaluateSExtd(PN->getIncomingValue(i), Ty)) return false;
|
|
return true;
|
|
}
|
|
default:
|
|
// TODO: Can handle more cases here.
|
|
break;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSExt(SExtInst &CI) {
|
|
// If this sign extend is only used by a truncate, let the truncate be
|
|
// eliminated before we try to optimize this sext.
|
|
if (CI.hasOneUse() && isa<TruncInst>(CI.user_back()))
|
|
return nullptr;
|
|
|
|
if (Instruction *I = commonCastTransforms(CI))
|
|
return I;
|
|
|
|
// See if we can simplify any instructions used by the input whose sole
|
|
// purpose is to compute bits we don't care about.
|
|
if (SimplifyDemandedInstructionBits(CI))
|
|
return &CI;
|
|
|
|
Value *Src = CI.getOperand(0);
|
|
Type *SrcTy = Src->getType(), *DestTy = CI.getType();
|
|
|
|
// Attempt to extend the entire input expression tree to the destination
|
|
// type. Only do this if the dest type is a simple type, don't convert the
|
|
// expression tree to something weird like i93 unless the source is also
|
|
// strange.
|
|
if ((DestTy->isVectorTy() || ShouldChangeType(SrcTy, DestTy)) &&
|
|
CanEvaluateSExtd(Src, DestTy)) {
|
|
// Okay, we can transform this! Insert the new expression now.
|
|
DEBUG(dbgs() << "ICE: EvaluateInDifferentType converting expression type"
|
|
" to avoid sign extend: " << CI);
|
|
Value *Res = EvaluateInDifferentType(Src, DestTy, true);
|
|
assert(Res->getType() == DestTy);
|
|
|
|
uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
|
|
uint32_t DestBitSize = DestTy->getScalarSizeInBits();
|
|
|
|
// If the high bits are already filled with sign bit, just replace this
|
|
// cast with the result.
|
|
if (ComputeNumSignBits(Res, 0, &CI) > DestBitSize - SrcBitSize)
|
|
return ReplaceInstUsesWith(CI, Res);
|
|
|
|
// We need to emit a shl + ashr to do the sign extend.
|
|
Value *ShAmt = ConstantInt::get(DestTy, DestBitSize-SrcBitSize);
|
|
return BinaryOperator::CreateAShr(Builder->CreateShl(Res, ShAmt, "sext"),
|
|
ShAmt);
|
|
}
|
|
|
|
// If this input is a trunc from our destination, then turn sext(trunc(x))
|
|
// into shifts.
|
|
if (TruncInst *TI = dyn_cast<TruncInst>(Src))
|
|
if (TI->hasOneUse() && TI->getOperand(0)->getType() == DestTy) {
|
|
uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
|
|
uint32_t DestBitSize = DestTy->getScalarSizeInBits();
|
|
|
|
// We need to emit a shl + ashr to do the sign extend.
|
|
Value *ShAmt = ConstantInt::get(DestTy, DestBitSize-SrcBitSize);
|
|
Value *Res = Builder->CreateShl(TI->getOperand(0), ShAmt, "sext");
|
|
return BinaryOperator::CreateAShr(Res, ShAmt);
|
|
}
|
|
|
|
if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
|
|
return transformSExtICmp(ICI, CI);
|
|
|
|
// If the input is a shl/ashr pair of a same constant, then this is a sign
|
|
// extension from a smaller value. If we could trust arbitrary bitwidth
|
|
// integers, we could turn this into a truncate to the smaller bit and then
|
|
// use a sext for the whole extension. Since we don't, look deeper and check
|
|
// for a truncate. If the source and dest are the same type, eliminate the
|
|
// trunc and extend and just do shifts. For example, turn:
|
|
// %a = trunc i32 %i to i8
|
|
// %b = shl i8 %a, 6
|
|
// %c = ashr i8 %b, 6
|
|
// %d = sext i8 %c to i32
|
|
// into:
|
|
// %a = shl i32 %i, 30
|
|
// %d = ashr i32 %a, 30
|
|
Value *A = nullptr;
|
|
// TODO: Eventually this could be subsumed by EvaluateInDifferentType.
|
|
ConstantInt *BA = nullptr, *CA = nullptr;
|
|
if (match(Src, m_AShr(m_Shl(m_Trunc(m_Value(A)), m_ConstantInt(BA)),
|
|
m_ConstantInt(CA))) &&
|
|
BA == CA && A->getType() == CI.getType()) {
|
|
unsigned MidSize = Src->getType()->getScalarSizeInBits();
|
|
unsigned SrcDstSize = CI.getType()->getScalarSizeInBits();
|
|
unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
|
|
Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
|
|
A = Builder->CreateShl(A, ShAmtV, CI.getName());
|
|
return BinaryOperator::CreateAShr(A, ShAmtV);
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
|
|
/// FitsInFPType - Return a Constant* for the specified FP constant if it fits
|
|
/// in the specified FP type without changing its value.
|
|
static Constant *FitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) {
|
|
bool losesInfo;
|
|
APFloat F = CFP->getValueAPF();
|
|
(void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
|
|
if (!losesInfo)
|
|
return ConstantFP::get(CFP->getContext(), F);
|
|
return nullptr;
|
|
}
|
|
|
|
/// LookThroughFPExtensions - If this is an fp extension instruction, look
|
|
/// through it until we get the source value.
|
|
static Value *LookThroughFPExtensions(Value *V) {
|
|
if (Instruction *I = dyn_cast<Instruction>(V))
|
|
if (I->getOpcode() == Instruction::FPExt)
|
|
return LookThroughFPExtensions(I->getOperand(0));
|
|
|
|
// If this value is a constant, return the constant in the smallest FP type
|
|
// that can accurately represent it. This allows us to turn
|
|
// (float)((double)X+2.0) into x+2.0f.
|
|
if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
|
|
if (CFP->getType() == Type::getPPC_FP128Ty(V->getContext()))
|
|
return V; // No constant folding of this.
|
|
// See if the value can be truncated to half and then reextended.
|
|
if (Value *V = FitsInFPType(CFP, APFloat::IEEEhalf))
|
|
return V;
|
|
// See if the value can be truncated to float and then reextended.
|
|
if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle))
|
|
return V;
|
|
if (CFP->getType()->isDoubleTy())
|
|
return V; // Won't shrink.
|
|
if (Value *V = FitsInFPType(CFP, APFloat::IEEEdouble))
|
|
return V;
|
|
// Don't try to shrink to various long double types.
|
|
}
|
|
|
|
return V;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) {
|
|
if (Instruction *I = commonCastTransforms(CI))
|
|
return I;
|
|
// If we have fptrunc(OpI (fpextend x), (fpextend y)), we would like to
|
|
// simpilify this expression to avoid one or more of the trunc/extend
|
|
// operations if we can do so without changing the numerical results.
|
|
//
|
|
// The exact manner in which the widths of the operands interact to limit
|
|
// what we can and cannot do safely varies from operation to operation, and
|
|
// is explained below in the various case statements.
|
|
BinaryOperator *OpI = dyn_cast<BinaryOperator>(CI.getOperand(0));
|
|
if (OpI && OpI->hasOneUse()) {
|
|
Value *LHSOrig = LookThroughFPExtensions(OpI->getOperand(0));
|
|
Value *RHSOrig = LookThroughFPExtensions(OpI->getOperand(1));
|
|
unsigned OpWidth = OpI->getType()->getFPMantissaWidth();
|
|
unsigned LHSWidth = LHSOrig->getType()->getFPMantissaWidth();
|
|
unsigned RHSWidth = RHSOrig->getType()->getFPMantissaWidth();
|
|
unsigned SrcWidth = std::max(LHSWidth, RHSWidth);
|
|
unsigned DstWidth = CI.getType()->getFPMantissaWidth();
|
|
switch (OpI->getOpcode()) {
|
|
default: break;
|
|
case Instruction::FAdd:
|
|
case Instruction::FSub:
|
|
// For addition and subtraction, the infinitely precise result can
|
|
// essentially be arbitrarily wide; proving that double rounding
|
|
// will not occur because the result of OpI is exact (as we will for
|
|
// FMul, for example) is hopeless. However, we *can* nonetheless
|
|
// frequently know that double rounding cannot occur (or that it is
|
|
// innocuous) by taking advantage of the specific structure of
|
|
// infinitely-precise results that admit double rounding.
|
|
//
|
|
// Specifically, if OpWidth >= 2*DstWdith+1 and DstWidth is sufficient
|
|
// to represent both sources, we can guarantee that the double
|
|
// rounding is innocuous (See p50 of Figueroa's 2000 PhD thesis,
|
|
// "A Rigorous Framework for Fully Supporting the IEEE Standard ..."
|
|
// for proof of this fact).
|
|
//
|
|
// Note: Figueroa does not consider the case where DstFormat !=
|
|
// SrcFormat. It's possible (likely even!) that this analysis
|
|
// could be tightened for those cases, but they are rare (the main
|
|
// case of interest here is (float)((double)float + float)).
|
|
if (OpWidth >= 2*DstWidth+1 && DstWidth >= SrcWidth) {
|
|
if (LHSOrig->getType() != CI.getType())
|
|
LHSOrig = Builder->CreateFPExt(LHSOrig, CI.getType());
|
|
if (RHSOrig->getType() != CI.getType())
|
|
RHSOrig = Builder->CreateFPExt(RHSOrig, CI.getType());
|
|
Instruction *RI =
|
|
BinaryOperator::Create(OpI->getOpcode(), LHSOrig, RHSOrig);
|
|
RI->copyFastMathFlags(OpI);
|
|
return RI;
|
|
}
|
|
break;
|
|
case Instruction::FMul:
|
|
// For multiplication, the infinitely precise result has at most
|
|
// LHSWidth + RHSWidth significant bits; if OpWidth is sufficient
|
|
// that such a value can be exactly represented, then no double
|
|
// rounding can possibly occur; we can safely perform the operation
|
|
// in the destination format if it can represent both sources.
|
|
if (OpWidth >= LHSWidth + RHSWidth && DstWidth >= SrcWidth) {
|
|
if (LHSOrig->getType() != CI.getType())
|
|
LHSOrig = Builder->CreateFPExt(LHSOrig, CI.getType());
|
|
if (RHSOrig->getType() != CI.getType())
|
|
RHSOrig = Builder->CreateFPExt(RHSOrig, CI.getType());
|
|
Instruction *RI =
|
|
BinaryOperator::CreateFMul(LHSOrig, RHSOrig);
|
|
RI->copyFastMathFlags(OpI);
|
|
return RI;
|
|
}
|
|
break;
|
|
case Instruction::FDiv:
|
|
// For division, we use again use the bound from Figueroa's
|
|
// dissertation. I am entirely certain that this bound can be
|
|
// tightened in the unbalanced operand case by an analysis based on
|
|
// the diophantine rational approximation bound, but the well-known
|
|
// condition used here is a good conservative first pass.
|
|
// TODO: Tighten bound via rigorous analysis of the unbalanced case.
|
|
if (OpWidth >= 2*DstWidth && DstWidth >= SrcWidth) {
|
|
if (LHSOrig->getType() != CI.getType())
|
|
LHSOrig = Builder->CreateFPExt(LHSOrig, CI.getType());
|
|
if (RHSOrig->getType() != CI.getType())
|
|
RHSOrig = Builder->CreateFPExt(RHSOrig, CI.getType());
|
|
Instruction *RI =
|
|
BinaryOperator::CreateFDiv(LHSOrig, RHSOrig);
|
|
RI->copyFastMathFlags(OpI);
|
|
return RI;
|
|
}
|
|
break;
|
|
case Instruction::FRem:
|
|
// Remainder is straightforward. Remainder is always exact, so the
|
|
// type of OpI doesn't enter into things at all. We simply evaluate
|
|
// in whichever source type is larger, then convert to the
|
|
// destination type.
|
|
if (LHSWidth < SrcWidth)
|
|
LHSOrig = Builder->CreateFPExt(LHSOrig, RHSOrig->getType());
|
|
else if (RHSWidth <= SrcWidth)
|
|
RHSOrig = Builder->CreateFPExt(RHSOrig, LHSOrig->getType());
|
|
Value *ExactResult = Builder->CreateFRem(LHSOrig, RHSOrig);
|
|
if (Instruction *RI = dyn_cast<Instruction>(ExactResult))
|
|
RI->copyFastMathFlags(OpI);
|
|
return CastInst::CreateFPCast(ExactResult, CI.getType());
|
|
}
|
|
|
|
// (fptrunc (fneg x)) -> (fneg (fptrunc x))
|
|
if (BinaryOperator::isFNeg(OpI)) {
|
|
Value *InnerTrunc = Builder->CreateFPTrunc(OpI->getOperand(1),
|
|
CI.getType());
|
|
Instruction *RI = BinaryOperator::CreateFNeg(InnerTrunc);
|
|
RI->copyFastMathFlags(OpI);
|
|
return RI;
|
|
}
|
|
}
|
|
|
|
// (fptrunc (select cond, R1, Cst)) -->
|
|
// (select cond, (fptrunc R1), (fptrunc Cst))
|
|
SelectInst *SI = dyn_cast<SelectInst>(CI.getOperand(0));
|
|
if (SI &&
|
|
(isa<ConstantFP>(SI->getOperand(1)) ||
|
|
isa<ConstantFP>(SI->getOperand(2)))) {
|
|
Value *LHSTrunc = Builder->CreateFPTrunc(SI->getOperand(1),
|
|
CI.getType());
|
|
Value *RHSTrunc = Builder->CreateFPTrunc(SI->getOperand(2),
|
|
CI.getType());
|
|
return SelectInst::Create(SI->getOperand(0), LHSTrunc, RHSTrunc);
|
|
}
|
|
|
|
IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI.getOperand(0));
|
|
if (II) {
|
|
switch (II->getIntrinsicID()) {
|
|
default: break;
|
|
case Intrinsic::fabs: {
|
|
// (fptrunc (fabs x)) -> (fabs (fptrunc x))
|
|
Value *InnerTrunc = Builder->CreateFPTrunc(II->getArgOperand(0),
|
|
CI.getType());
|
|
Type *IntrinsicType[] = { CI.getType() };
|
|
Function *Overload =
|
|
Intrinsic::getDeclaration(CI.getParent()->getParent()->getParent(),
|
|
II->getIntrinsicID(), IntrinsicType);
|
|
|
|
Value *Args[] = { InnerTrunc };
|
|
return CallInst::Create(Overload, Args, II->getName());
|
|
}
|
|
}
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFPExt(CastInst &CI) {
|
|
return commonCastTransforms(CI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
|
|
Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
|
|
if (!OpI)
|
|
return commonCastTransforms(FI);
|
|
|
|
// fptoui(uitofp(X)) --> X
|
|
// fptoui(sitofp(X)) --> X
|
|
// This is safe if the intermediate type has enough bits in its mantissa to
|
|
// accurately represent all values of X. For example, do not do this with
|
|
// i64->float->i64. This is also safe for sitofp case, because any negative
|
|
// 'X' value would cause an undefined result for the fptoui.
|
|
if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
|
|
OpI->getOperand(0)->getType() == FI.getType() &&
|
|
(int)FI.getType()->getScalarSizeInBits() < /*extra bit for sign */
|
|
OpI->getType()->getFPMantissaWidth())
|
|
return ReplaceInstUsesWith(FI, OpI->getOperand(0));
|
|
|
|
return commonCastTransforms(FI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
|
|
Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
|
|
if (!OpI)
|
|
return commonCastTransforms(FI);
|
|
|
|
// fptosi(sitofp(X)) --> X
|
|
// fptosi(uitofp(X)) --> X
|
|
// This is safe if the intermediate type has enough bits in its mantissa to
|
|
// accurately represent all values of X. For example, do not do this with
|
|
// i64->float->i64. This is also safe for sitofp case, because any negative
|
|
// 'X' value would cause an undefined result for the fptoui.
|
|
if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
|
|
OpI->getOperand(0)->getType() == FI.getType() &&
|
|
(int)FI.getType()->getScalarSizeInBits() <=
|
|
OpI->getType()->getFPMantissaWidth())
|
|
return ReplaceInstUsesWith(FI, OpI->getOperand(0));
|
|
|
|
return commonCastTransforms(FI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
|
|
return commonCastTransforms(CI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
|
|
return commonCastTransforms(CI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) {
|
|
// If the source integer type is not the intptr_t type for this target, do a
|
|
// trunc or zext to the intptr_t type, then inttoptr of it. This allows the
|
|
// cast to be exposed to other transforms.
|
|
|
|
if (DL) {
|
|
unsigned AS = CI.getAddressSpace();
|
|
if (CI.getOperand(0)->getType()->getScalarSizeInBits() !=
|
|
DL->getPointerSizeInBits(AS)) {
|
|
Type *Ty = DL->getIntPtrType(CI.getContext(), AS);
|
|
if (CI.getType()->isVectorTy()) // Handle vectors of pointers.
|
|
Ty = VectorType::get(Ty, CI.getType()->getVectorNumElements());
|
|
|
|
Value *P = Builder->CreateZExtOrTrunc(CI.getOperand(0), Ty);
|
|
return new IntToPtrInst(P, CI.getType());
|
|
}
|
|
}
|
|
|
|
if (Instruction *I = commonCastTransforms(CI))
|
|
return I;
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint)
|
|
Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
|
|
Value *Src = CI.getOperand(0);
|
|
|
|
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
|
|
// If casting the result of a getelementptr instruction with no offset, turn
|
|
// this into a cast of the original pointer!
|
|
if (GEP->hasAllZeroIndices() &&
|
|
// If CI is an addrspacecast and GEP changes the poiner type, merging
|
|
// GEP into CI would undo canonicalizing addrspacecast with different
|
|
// pointer types, causing infinite loops.
|
|
(!isa<AddrSpaceCastInst>(CI) ||
|
|
GEP->getType() == GEP->getPointerOperand()->getType())) {
|
|
// Changing the cast operand is usually not a good idea but it is safe
|
|
// here because the pointer operand is being replaced with another
|
|
// pointer operand so the opcode doesn't need to change.
|
|
Worklist.Add(GEP);
|
|
CI.setOperand(0, GEP->getOperand(0));
|
|
return &CI;
|
|
}
|
|
|
|
if (!DL)
|
|
return commonCastTransforms(CI);
|
|
|
|
// If the GEP has a single use, and the base pointer is a bitcast, and the
|
|
// GEP computes a constant offset, see if we can convert these three
|
|
// instructions into fewer. This typically happens with unions and other
|
|
// non-type-safe code.
|
|
unsigned AS = GEP->getPointerAddressSpace();
|
|
unsigned OffsetBits = DL->getPointerSizeInBits(AS);
|
|
APInt Offset(OffsetBits, 0);
|
|
BitCastInst *BCI = dyn_cast<BitCastInst>(GEP->getOperand(0));
|
|
if (GEP->hasOneUse() &&
|
|
BCI &&
|
|
GEP->accumulateConstantOffset(*DL, Offset)) {
|
|
// Get the base pointer input of the bitcast, and the type it points to.
|
|
Value *OrigBase = BCI->getOperand(0);
|
|
SmallVector<Value*, 8> NewIndices;
|
|
if (FindElementAtOffset(OrigBase->getType(),
|
|
Offset.getSExtValue(),
|
|
NewIndices)) {
|
|
// If we were able to index down into an element, create the GEP
|
|
// and bitcast the result. This eliminates one bitcast, potentially
|
|
// two.
|
|
Value *NGEP = cast<GEPOperator>(GEP)->isInBounds() ?
|
|
Builder->CreateInBoundsGEP(OrigBase, NewIndices) :
|
|
Builder->CreateGEP(OrigBase, NewIndices);
|
|
NGEP->takeName(GEP);
|
|
|
|
if (isa<BitCastInst>(CI))
|
|
return new BitCastInst(NGEP, CI.getType());
|
|
assert(isa<PtrToIntInst>(CI));
|
|
return new PtrToIntInst(NGEP, CI.getType());
|
|
}
|
|
}
|
|
}
|
|
|
|
return commonCastTransforms(CI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitPtrToInt(PtrToIntInst &CI) {
|
|
// If the destination integer type is not the intptr_t type for this target,
|
|
// do a ptrtoint to intptr_t then do a trunc or zext. This allows the cast
|
|
// to be exposed to other transforms.
|
|
|
|
if (!DL)
|
|
return commonPointerCastTransforms(CI);
|
|
|
|
Type *Ty = CI.getType();
|
|
unsigned AS = CI.getPointerAddressSpace();
|
|
|
|
if (Ty->getScalarSizeInBits() == DL->getPointerSizeInBits(AS))
|
|
return commonPointerCastTransforms(CI);
|
|
|
|
Type *PtrTy = DL->getIntPtrType(CI.getContext(), AS);
|
|
if (Ty->isVectorTy()) // Handle vectors of pointers.
|
|
PtrTy = VectorType::get(PtrTy, Ty->getVectorNumElements());
|
|
|
|
Value *P = Builder->CreatePtrToInt(CI.getOperand(0), PtrTy);
|
|
return CastInst::CreateIntegerCast(P, Ty, /*isSigned=*/false);
|
|
}
|
|
|
|
/// OptimizeVectorResize - This input value (which is known to have vector type)
|
|
/// is being zero extended or truncated to the specified vector type. Try to
|
|
/// replace it with a shuffle (and vector/vector bitcast) if possible.
|
|
///
|
|
/// The source and destination vector types may have different element types.
|
|
static Instruction *OptimizeVectorResize(Value *InVal, VectorType *DestTy,
|
|
InstCombiner &IC) {
|
|
// We can only do this optimization if the output is a multiple of the input
|
|
// element size, or the input is a multiple of the output element size.
|
|
// Convert the input type to have the same element type as the output.
|
|
VectorType *SrcTy = cast<VectorType>(InVal->getType());
|
|
|
|
if (SrcTy->getElementType() != DestTy->getElementType()) {
|
|
// The input types don't need to be identical, but for now they must be the
|
|
// same size. There is no specific reason we couldn't handle things like
|
|
// <4 x i16> -> <4 x i32> by bitcasting to <2 x i32> but haven't gotten
|
|
// there yet.
|
|
if (SrcTy->getElementType()->getPrimitiveSizeInBits() !=
|
|
DestTy->getElementType()->getPrimitiveSizeInBits())
|
|
return nullptr;
|
|
|
|
SrcTy = VectorType::get(DestTy->getElementType(), SrcTy->getNumElements());
|
|
InVal = IC.Builder->CreateBitCast(InVal, SrcTy);
|
|
}
|
|
|
|
// Now that the element types match, get the shuffle mask and RHS of the
|
|
// shuffle to use, which depends on whether we're increasing or decreasing the
|
|
// size of the input.
|
|
SmallVector<uint32_t, 16> ShuffleMask;
|
|
Value *V2;
|
|
|
|
if (SrcTy->getNumElements() > DestTy->getNumElements()) {
|
|
// If we're shrinking the number of elements, just shuffle in the low
|
|
// elements from the input and use undef as the second shuffle input.
|
|
V2 = UndefValue::get(SrcTy);
|
|
for (unsigned i = 0, e = DestTy->getNumElements(); i != e; ++i)
|
|
ShuffleMask.push_back(i);
|
|
|
|
} else {
|
|
// If we're increasing the number of elements, shuffle in all of the
|
|
// elements from InVal and fill the rest of the result elements with zeros
|
|
// from a constant zero.
|
|
V2 = Constant::getNullValue(SrcTy);
|
|
unsigned SrcElts = SrcTy->getNumElements();
|
|
for (unsigned i = 0, e = SrcElts; i != e; ++i)
|
|
ShuffleMask.push_back(i);
|
|
|
|
// The excess elements reference the first element of the zero input.
|
|
for (unsigned i = 0, e = DestTy->getNumElements()-SrcElts; i != e; ++i)
|
|
ShuffleMask.push_back(SrcElts);
|
|
}
|
|
|
|
return new ShuffleVectorInst(InVal, V2,
|
|
ConstantDataVector::get(V2->getContext(),
|
|
ShuffleMask));
|
|
}
|
|
|
|
static bool isMultipleOfTypeSize(unsigned Value, Type *Ty) {
|
|
return Value % Ty->getPrimitiveSizeInBits() == 0;
|
|
}
|
|
|
|
static unsigned getTypeSizeIndex(unsigned Value, Type *Ty) {
|
|
return Value / Ty->getPrimitiveSizeInBits();
|
|
}
|
|
|
|
/// CollectInsertionElements - V is a value which is inserted into a vector of
|
|
/// VecEltTy. Look through the value to see if we can decompose it into
|
|
/// insertions into the vector. See the example in the comment for
|
|
/// OptimizeIntegerToVectorInsertions for the pattern this handles.
|
|
/// The type of V is always a non-zero multiple of VecEltTy's size.
|
|
/// Shift is the number of bits between the lsb of V and the lsb of
|
|
/// the vector.
|
|
///
|
|
/// This returns false if the pattern can't be matched or true if it can,
|
|
/// filling in Elements with the elements found here.
|
|
static bool CollectInsertionElements(Value *V, unsigned Shift,
|
|
SmallVectorImpl<Value*> &Elements,
|
|
Type *VecEltTy, InstCombiner &IC) {
|
|
assert(isMultipleOfTypeSize(Shift, VecEltTy) &&
|
|
"Shift should be a multiple of the element type size");
|
|
|
|
// Undef values never contribute useful bits to the result.
|
|
if (isa<UndefValue>(V)) return true;
|
|
|
|
// If we got down to a value of the right type, we win, try inserting into the
|
|
// right element.
|
|
if (V->getType() == VecEltTy) {
|
|
// Inserting null doesn't actually insert any elements.
|
|
if (Constant *C = dyn_cast<Constant>(V))
|
|
if (C->isNullValue())
|
|
return true;
|
|
|
|
unsigned ElementIndex = getTypeSizeIndex(Shift, VecEltTy);
|
|
if (IC.getDataLayout()->isBigEndian())
|
|
ElementIndex = Elements.size() - ElementIndex - 1;
|
|
|
|
// Fail if multiple elements are inserted into this slot.
|
|
if (Elements[ElementIndex])
|
|
return false;
|
|
|
|
Elements[ElementIndex] = V;
|
|
return true;
|
|
}
|
|
|
|
if (Constant *C = dyn_cast<Constant>(V)) {
|
|
// Figure out the # elements this provides, and bitcast it or slice it up
|
|
// as required.
|
|
unsigned NumElts = getTypeSizeIndex(C->getType()->getPrimitiveSizeInBits(),
|
|
VecEltTy);
|
|
// If the constant is the size of a vector element, we just need to bitcast
|
|
// it to the right type so it gets properly inserted.
|
|
if (NumElts == 1)
|
|
return CollectInsertionElements(ConstantExpr::getBitCast(C, VecEltTy),
|
|
Shift, Elements, VecEltTy, IC);
|
|
|
|
// Okay, this is a constant that covers multiple elements. Slice it up into
|
|
// pieces and insert each element-sized piece into the vector.
|
|
if (!isa<IntegerType>(C->getType()))
|
|
C = ConstantExpr::getBitCast(C, IntegerType::get(V->getContext(),
|
|
C->getType()->getPrimitiveSizeInBits()));
|
|
unsigned ElementSize = VecEltTy->getPrimitiveSizeInBits();
|
|
Type *ElementIntTy = IntegerType::get(C->getContext(), ElementSize);
|
|
|
|
for (unsigned i = 0; i != NumElts; ++i) {
|
|
unsigned ShiftI = Shift+i*ElementSize;
|
|
Constant *Piece = ConstantExpr::getLShr(C, ConstantInt::get(C->getType(),
|
|
ShiftI));
|
|
Piece = ConstantExpr::getTrunc(Piece, ElementIntTy);
|
|
if (!CollectInsertionElements(Piece, ShiftI, Elements, VecEltTy, IC))
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
if (!V->hasOneUse()) return false;
|
|
|
|
Instruction *I = dyn_cast<Instruction>(V);
|
|
if (!I) return false;
|
|
switch (I->getOpcode()) {
|
|
default: return false; // Unhandled case.
|
|
case Instruction::BitCast:
|
|
return CollectInsertionElements(I->getOperand(0), Shift,
|
|
Elements, VecEltTy, IC);
|
|
case Instruction::ZExt:
|
|
if (!isMultipleOfTypeSize(
|
|
I->getOperand(0)->getType()->getPrimitiveSizeInBits(),
|
|
VecEltTy))
|
|
return false;
|
|
return CollectInsertionElements(I->getOperand(0), Shift,
|
|
Elements, VecEltTy, IC);
|
|
case Instruction::Or:
|
|
return CollectInsertionElements(I->getOperand(0), Shift,
|
|
Elements, VecEltTy, IC) &&
|
|
CollectInsertionElements(I->getOperand(1), Shift,
|
|
Elements, VecEltTy, IC);
|
|
case Instruction::Shl: {
|
|
// Must be shifting by a constant that is a multiple of the element size.
|
|
ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1));
|
|
if (!CI) return false;
|
|
Shift += CI->getZExtValue();
|
|
if (!isMultipleOfTypeSize(Shift, VecEltTy)) return false;
|
|
return CollectInsertionElements(I->getOperand(0), Shift,
|
|
Elements, VecEltTy, IC);
|
|
}
|
|
|
|
}
|
|
}
|
|
|
|
|
|
/// OptimizeIntegerToVectorInsertions - If the input is an 'or' instruction, we
|
|
/// may be doing shifts and ors to assemble the elements of the vector manually.
|
|
/// Try to rip the code out and replace it with insertelements. This is to
|
|
/// optimize code like this:
|
|
///
|
|
/// %tmp37 = bitcast float %inc to i32
|
|
/// %tmp38 = zext i32 %tmp37 to i64
|
|
/// %tmp31 = bitcast float %inc5 to i32
|
|
/// %tmp32 = zext i32 %tmp31 to i64
|
|
/// %tmp33 = shl i64 %tmp32, 32
|
|
/// %ins35 = or i64 %tmp33, %tmp38
|
|
/// %tmp43 = bitcast i64 %ins35 to <2 x float>
|
|
///
|
|
/// Into two insertelements that do "buildvector{%inc, %inc5}".
|
|
static Value *OptimizeIntegerToVectorInsertions(BitCastInst &CI,
|
|
InstCombiner &IC) {
|
|
// We need to know the target byte order to perform this optimization.
|
|
if (!IC.getDataLayout()) return nullptr;
|
|
|
|
VectorType *DestVecTy = cast<VectorType>(CI.getType());
|
|
Value *IntInput = CI.getOperand(0);
|
|
|
|
SmallVector<Value*, 8> Elements(DestVecTy->getNumElements());
|
|
if (!CollectInsertionElements(IntInput, 0, Elements,
|
|
DestVecTy->getElementType(), IC))
|
|
return nullptr;
|
|
|
|
// If we succeeded, we know that all of the element are specified by Elements
|
|
// or are zero if Elements has a null entry. Recast this as a set of
|
|
// insertions.
|
|
Value *Result = Constant::getNullValue(CI.getType());
|
|
for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
|
|
if (!Elements[i]) continue; // Unset element.
|
|
|
|
Result = IC.Builder->CreateInsertElement(Result, Elements[i],
|
|
IC.Builder->getInt32(i));
|
|
}
|
|
|
|
return Result;
|
|
}
|
|
|
|
|
|
/// OptimizeIntToFloatBitCast - See if we can optimize an integer->float/double
|
|
/// bitcast. The various long double bitcasts can't get in here.
|
|
static Instruction *OptimizeIntToFloatBitCast(BitCastInst &CI,InstCombiner &IC){
|
|
// We need to know the target byte order to perform this optimization.
|
|
if (!IC.getDataLayout()) return nullptr;
|
|
|
|
Value *Src = CI.getOperand(0);
|
|
Type *DestTy = CI.getType();
|
|
|
|
// If this is a bitcast from int to float, check to see if the int is an
|
|
// extraction from a vector.
|
|
Value *VecInput = nullptr;
|
|
// bitcast(trunc(bitcast(somevector)))
|
|
if (match(Src, m_Trunc(m_BitCast(m_Value(VecInput)))) &&
|
|
isa<VectorType>(VecInput->getType())) {
|
|
VectorType *VecTy = cast<VectorType>(VecInput->getType());
|
|
unsigned DestWidth = DestTy->getPrimitiveSizeInBits();
|
|
|
|
if (VecTy->getPrimitiveSizeInBits() % DestWidth == 0) {
|
|
// If the element type of the vector doesn't match the result type,
|
|
// bitcast it to be a vector type we can extract from.
|
|
if (VecTy->getElementType() != DestTy) {
|
|
VecTy = VectorType::get(DestTy,
|
|
VecTy->getPrimitiveSizeInBits() / DestWidth);
|
|
VecInput = IC.Builder->CreateBitCast(VecInput, VecTy);
|
|
}
|
|
|
|
unsigned Elt = 0;
|
|
if (IC.getDataLayout()->isBigEndian())
|
|
Elt = VecTy->getPrimitiveSizeInBits() / DestWidth - 1;
|
|
return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(Elt));
|
|
}
|
|
}
|
|
|
|
// bitcast(trunc(lshr(bitcast(somevector), cst))
|
|
ConstantInt *ShAmt = nullptr;
|
|
if (match(Src, m_Trunc(m_LShr(m_BitCast(m_Value(VecInput)),
|
|
m_ConstantInt(ShAmt)))) &&
|
|
isa<VectorType>(VecInput->getType())) {
|
|
VectorType *VecTy = cast<VectorType>(VecInput->getType());
|
|
unsigned DestWidth = DestTy->getPrimitiveSizeInBits();
|
|
if (VecTy->getPrimitiveSizeInBits() % DestWidth == 0 &&
|
|
ShAmt->getZExtValue() % DestWidth == 0) {
|
|
// If the element type of the vector doesn't match the result type,
|
|
// bitcast it to be a vector type we can extract from.
|
|
if (VecTy->getElementType() != DestTy) {
|
|
VecTy = VectorType::get(DestTy,
|
|
VecTy->getPrimitiveSizeInBits() / DestWidth);
|
|
VecInput = IC.Builder->CreateBitCast(VecInput, VecTy);
|
|
}
|
|
|
|
unsigned Elt = ShAmt->getZExtValue() / DestWidth;
|
|
if (IC.getDataLayout()->isBigEndian())
|
|
Elt = VecTy->getPrimitiveSizeInBits() / DestWidth - 1 - Elt;
|
|
return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(Elt));
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
|
|
// If the operands are integer typed then apply the integer transforms,
|
|
// otherwise just apply the common ones.
|
|
Value *Src = CI.getOperand(0);
|
|
Type *SrcTy = Src->getType();
|
|
Type *DestTy = CI.getType();
|
|
|
|
// Get rid of casts from one type to the same type. These are useless and can
|
|
// be replaced by the operand.
|
|
if (DestTy == Src->getType())
|
|
return ReplaceInstUsesWith(CI, Src);
|
|
|
|
if (PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
|
|
PointerType *SrcPTy = cast<PointerType>(SrcTy);
|
|
Type *DstElTy = DstPTy->getElementType();
|
|
Type *SrcElTy = SrcPTy->getElementType();
|
|
|
|
// If we are casting a alloca to a pointer to a type of the same
|
|
// size, rewrite the allocation instruction to allocate the "right" type.
|
|
// There is no need to modify malloc calls because it is their bitcast that
|
|
// needs to be cleaned up.
|
|
if (AllocaInst *AI = dyn_cast<AllocaInst>(Src))
|
|
if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
|
|
return V;
|
|
|
|
// If the source and destination are pointers, and this cast is equivalent
|
|
// to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
|
|
// This can enhance SROA and other transforms that want type-safe pointers.
|
|
Constant *ZeroUInt =
|
|
Constant::getNullValue(Type::getInt32Ty(CI.getContext()));
|
|
unsigned NumZeros = 0;
|
|
while (SrcElTy != DstElTy &&
|
|
isa<CompositeType>(SrcElTy) && !SrcElTy->isPointerTy() &&
|
|
SrcElTy->getNumContainedTypes() /* not "{}" */) {
|
|
SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
|
|
++NumZeros;
|
|
}
|
|
|
|
// If we found a path from the src to dest, create the getelementptr now.
|
|
if (SrcElTy == DstElTy) {
|
|
SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
|
|
return GetElementPtrInst::CreateInBounds(Src, Idxs);
|
|
}
|
|
}
|
|
|
|
// Try to optimize int -> float bitcasts.
|
|
if ((DestTy->isFloatTy() || DestTy->isDoubleTy()) && isa<IntegerType>(SrcTy))
|
|
if (Instruction *I = OptimizeIntToFloatBitCast(CI, *this))
|
|
return I;
|
|
|
|
if (VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
|
|
if (DestVTy->getNumElements() == 1 && !SrcTy->isVectorTy()) {
|
|
Value *Elem = Builder->CreateBitCast(Src, DestVTy->getElementType());
|
|
return InsertElementInst::Create(UndefValue::get(DestTy), Elem,
|
|
Constant::getNullValue(Type::getInt32Ty(CI.getContext())));
|
|
// FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
|
|
}
|
|
|
|
if (isa<IntegerType>(SrcTy)) {
|
|
// If this is a cast from an integer to vector, check to see if the input
|
|
// is a trunc or zext of a bitcast from vector. If so, we can replace all
|
|
// the casts with a shuffle and (potentially) a bitcast.
|
|
if (isa<TruncInst>(Src) || isa<ZExtInst>(Src)) {
|
|
CastInst *SrcCast = cast<CastInst>(Src);
|
|
if (BitCastInst *BCIn = dyn_cast<BitCastInst>(SrcCast->getOperand(0)))
|
|
if (isa<VectorType>(BCIn->getOperand(0)->getType()))
|
|
if (Instruction *I = OptimizeVectorResize(BCIn->getOperand(0),
|
|
cast<VectorType>(DestTy), *this))
|
|
return I;
|
|
}
|
|
|
|
// If the input is an 'or' instruction, we may be doing shifts and ors to
|
|
// assemble the elements of the vector manually. Try to rip the code out
|
|
// and replace it with insertelements.
|
|
if (Value *V = OptimizeIntegerToVectorInsertions(CI, *this))
|
|
return ReplaceInstUsesWith(CI, V);
|
|
}
|
|
}
|
|
|
|
if (VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) {
|
|
if (SrcVTy->getNumElements() == 1) {
|
|
// If our destination is not a vector, then make this a straight
|
|
// scalar-scalar cast.
|
|
if (!DestTy->isVectorTy()) {
|
|
Value *Elem =
|
|
Builder->CreateExtractElement(Src,
|
|
Constant::getNullValue(Type::getInt32Ty(CI.getContext())));
|
|
return CastInst::Create(Instruction::BitCast, Elem, DestTy);
|
|
}
|
|
|
|
// Otherwise, see if our source is an insert. If so, then use the scalar
|
|
// component directly.
|
|
if (InsertElementInst *IEI =
|
|
dyn_cast<InsertElementInst>(CI.getOperand(0)))
|
|
return CastInst::Create(Instruction::BitCast, IEI->getOperand(1),
|
|
DestTy);
|
|
}
|
|
}
|
|
|
|
if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
|
|
// Okay, we have (bitcast (shuffle ..)). Check to see if this is
|
|
// a bitcast to a vector with the same # elts.
|
|
if (SVI->hasOneUse() && DestTy->isVectorTy() &&
|
|
DestTy->getVectorNumElements() == SVI->getType()->getNumElements() &&
|
|
SVI->getType()->getNumElements() ==
|
|
SVI->getOperand(0)->getType()->getVectorNumElements()) {
|
|
BitCastInst *Tmp;
|
|
// If either of the operands is a cast from CI.getType(), then
|
|
// evaluating the shuffle in the casted destination's type will allow
|
|
// us to eliminate at least one cast.
|
|
if (((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(0))) &&
|
|
Tmp->getOperand(0)->getType() == DestTy) ||
|
|
((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(1))) &&
|
|
Tmp->getOperand(0)->getType() == DestTy)) {
|
|
Value *LHS = Builder->CreateBitCast(SVI->getOperand(0), DestTy);
|
|
Value *RHS = Builder->CreateBitCast(SVI->getOperand(1), DestTy);
|
|
// Return a new shuffle vector. Use the same element ID's, as we
|
|
// know the vector types match #elts.
|
|
return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
|
|
}
|
|
}
|
|
}
|
|
|
|
if (SrcTy->isPointerTy())
|
|
return commonPointerCastTransforms(CI);
|
|
return commonCastTransforms(CI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitAddrSpaceCast(AddrSpaceCastInst &CI) {
|
|
// If the destination pointer element type is not the same as the source's
|
|
// first do a bitcast to the destination type, and then the addrspacecast.
|
|
// This allows the cast to be exposed to other transforms.
|
|
Value *Src = CI.getOperand(0);
|
|
PointerType *SrcTy = cast<PointerType>(Src->getType()->getScalarType());
|
|
PointerType *DestTy = cast<PointerType>(CI.getType()->getScalarType());
|
|
|
|
Type *DestElemTy = DestTy->getElementType();
|
|
if (SrcTy->getElementType() != DestElemTy) {
|
|
Type *MidTy = PointerType::get(DestElemTy, SrcTy->getAddressSpace());
|
|
if (VectorType *VT = dyn_cast<VectorType>(CI.getType())) {
|
|
// Handle vectors of pointers.
|
|
MidTy = VectorType::get(MidTy, VT->getNumElements());
|
|
}
|
|
|
|
Value *NewBitCast = Builder->CreateBitCast(Src, MidTy);
|
|
return new AddrSpaceCastInst(NewBitCast, CI.getType());
|
|
}
|
|
|
|
return commonPointerCastTransforms(CI);
|
|
}
|