From 822cb58d087ab67804037807e130273481b86137 Mon Sep 17 00:00:00 2001 From: Bob Wilson Date: Fri, 29 Oct 2010 22:03:05 +0000 Subject: Change instcombine's getShuffleMask to represent undef with negative values. This code had previously used 2*N, where N is the mask length, to represent undef. That is not safe because the shufflevector operands may have more than N elements -- they don't have to match the result type. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117721 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../InstCombine/InstCombineVectorOps.cpp | 76 ++++++++++------------ 1 file changed, 36 insertions(+), 40 deletions(-) (limited to 'lib/Transforms/InstCombine/InstCombineVectorOps.cpp') diff --git a/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/lib/Transforms/InstCombine/InstCombineVectorOps.cpp index 634add8..2ebaadb 100644 --- a/lib/Transforms/InstCombine/InstCombineVectorOps.cpp +++ b/lib/Transforms/InstCombine/InstCombineVectorOps.cpp @@ -53,22 +53,20 @@ static bool CheapToScalarize(Value *V, bool isConstant) { return false; } -/// Read and decode a shufflevector mask. -/// -/// It turns undef elements into values that are larger than the number of -/// elements in the input. -static std::vector getShuffleMask(const ShuffleVectorInst *SVI) { +/// getShuffleMask - Read and decode a shufflevector mask. +/// Turn undef elements into negative values. +static std::vector getShuffleMask(const ShuffleVectorInst *SVI) { unsigned NElts = SVI->getType()->getNumElements(); if (isa(SVI->getOperand(2))) - return std::vector(NElts, 0); + return std::vector(NElts, 0); if (isa(SVI->getOperand(2))) - return std::vector(NElts, 2*NElts); + return std::vector(NElts, -1); - std::vector Result; + std::vector Result; const ConstantVector *CP = cast(SVI->getOperand(2)); for (User::const_op_iterator i = CP->op_begin(), e = CP->op_end(); i!=e; ++i) if (isa(*i)) - Result.push_back(NElts*2); // undef -> 8 + Result.push_back(-1); // undef else Result.push_back(cast(*i)->getZExtValue()); return Result; @@ -109,14 +107,13 @@ static Value *FindScalarElement(Value *V, unsigned EltNo) { if (ShuffleVectorInst *SVI = dyn_cast(V)) { unsigned LHSWidth = - cast(SVI->getOperand(0)->getType())->getNumElements(); - unsigned InEl = getShuffleMask(SVI)[EltNo]; - if (InEl < LHSWidth) - return FindScalarElement(SVI->getOperand(0), InEl); - else if (InEl < LHSWidth*2) - return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth); - else + cast(SVI->getOperand(0)->getType())->getNumElements(); + int InEl = getShuffleMask(SVI)[EltNo]; + if (InEl < 0) return UndefValue::get(PTy->getElementType()); + if (InEl < (int)LHSWidth) + return FindScalarElement(SVI->getOperand(0), InEl); + return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth); } // Otherwise, we don't know. @@ -215,18 +212,18 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) { // If this is extracting an element from a shufflevector, figure out where // it came from and extract from the appropriate input element instead. if (ConstantInt *Elt = dyn_cast(EI.getOperand(1))) { - unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()]; + int SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()]; Value *Src; unsigned LHSWidth = - cast(SVI->getOperand(0)->getType())->getNumElements(); + cast(SVI->getOperand(0)->getType())->getNumElements(); - if (SrcIdx < LHSWidth) + if (SrcIdx < 0) + return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType())); + if (SrcIdx < (int)LHSWidth) Src = SVI->getOperand(0); - else if (SrcIdx < LHSWidth*2) { + else { SrcIdx -= LHSWidth; Src = SVI->getOperand(1); - } else { - return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType())); } return ExtractElementInst::Create(Src, ConstantInt::get(Type::getInt32Ty(EI.getContext()), @@ -440,7 +437,7 @@ Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) { Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) { Value *LHS = SVI.getOperand(0); Value *RHS = SVI.getOperand(1); - std::vector Mask = getShuffleMask(&SVI); + std::vector Mask = getShuffleMask(&SVI); bool MadeChange = false; @@ -472,12 +469,12 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) { // Remap any references to RHS to use LHS. std::vector Elts; for (unsigned i = 0, e = Mask.size(); i != e; ++i) { - if (Mask[i] >= 2*e) + if (Mask[i] < 0) Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext()))); else { - if ((Mask[i] >= e && isa(RHS)) || - (Mask[i] < e && isa(LHS))) { - Mask[i] = 2*e; // Turn into undef. + if ((Mask[i] >= (int)e && isa(RHS)) || + (Mask[i] < (int)e && isa(LHS))) { + Mask[i] = -1; // Turn into undef. Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext()))); } else { Mask[i] = Mask[i] % e; // Force to LHS. @@ -498,9 +495,9 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) { bool isLHSID = true, isRHSID = true; for (unsigned i = 0, e = Mask.size(); i != e; ++i) { - if (Mask[i] >= e*2) continue; // Ignore undef values. + if (Mask[i] < 0) continue; // Ignore undef values. // Is this an identity shuffle of the LHS value? - isLHSID &= (Mask[i] == i); + isLHSID &= (Mask[i] == (int)i); // Is this an identity shuffle of the RHS value? isRHSID &= (Mask[i]-e == i); @@ -521,19 +518,21 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) { // turning: (splat(splat)) -> splat. if (ShuffleVectorInst *LHSSVI = dyn_cast(LHS)) { if (isa(RHS)) { - std::vector LHSMask = getShuffleMask(LHSSVI); + std::vector LHSMask = getShuffleMask(LHSSVI); if (LHSMask.size() == Mask.size()) { - std::vector NewMask; + std::vector NewMask; bool isSplat = true; - unsigned SplatElt = 2 * Mask.size(); // undef + int SplatElt = -1; // undef for (unsigned i = 0, e = Mask.size(); i != e; ++i) { - unsigned MaskElt = 2 * e; // undef - if (Mask[i] < e) + int MaskElt; + if (Mask[i] < 0 || Mask[i] >= (int)e) + MaskElt = -1; // undef + else MaskElt = LHSMask[Mask[i]]; // Check if this could still be a splat. - if (MaskElt < 2*e) { - if (SplatElt < 2*e && SplatElt != MaskElt) + if (MaskElt >= 0) { + if (SplatElt >=0 && SplatElt != MaskElt) isSplat = false; SplatElt = MaskElt; } @@ -543,13 +542,10 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) { // If the result mask is equal to the src shuffle or this // shuffle mask, do the replacement. if (isSplat || NewMask == LHSMask || NewMask == Mask) { - unsigned LHSInNElts = - cast(LHSSVI->getOperand(0)->getType())-> - getNumElements(); std::vector Elts; const Type *Int32Ty = Type::getInt32Ty(SVI.getContext()); for (unsigned i = 0, e = NewMask.size(); i != e; ++i) { - if (NewMask[i] >= LHSInNElts*2) { + if (NewMask[i] < 0) { Elts.push_back(UndefValue::get(Int32Ty)); } else { Elts.push_back(ConstantInt::get(Int32Ty, NewMask[i])); -- cgit v1.1