From 42d31c20a84af29b991d61eefec8d65378cf56f7 Mon Sep 17 00:00:00 2001 From: Sanjay Patel Date: Mon, 27 Aug 2018 22:41:44 +0000 Subject: [InstCombine] allow shuffle+binop canonicalization with widening shuffles This lines up with the behavior of an existing transform where if both operands of the binop are shuffled, we allow moving the binop before the shuffle regardless of whether the shuffle changes the size of the vector. llvm-svn: 340787 --- .../Transforms/InstCombine/InstructionCombining.cpp | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) (limited to 'llvm/lib/Transforms/InstCombine/InstructionCombining.cpp') diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index 99d3d478aaf..99874b31912 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -1393,7 +1393,10 @@ Instruction *InstCombiner::foldShuffledBinop(BinaryOperator &Inst) { if (match(&Inst, m_c_BinOp( m_OneUse(m_ShuffleVector(m_Value(V1), m_Undef(), m_Constant(Mask))), m_Constant(C))) && - V1->getType() == Inst.getType()) { + V1->getType()->getVectorNumElements() <= VWidth) { + assert(Inst.getType()->getScalarType() == V1->getType()->getScalarType() && + "Shuffle should not change scalar type"); + unsigned V1Width = V1->getType()->getVectorNumElements(); // Find constant NewC that has property: // shuffle(NewC, ShMask) = C // If such constant does not exist (example: ShMask=<0,0> and C=<1,2>) @@ -1402,14 +1405,21 @@ Instruction *InstCombiner::foldShuffledBinop(BinaryOperator &Inst) { SmallVector ShMask; ShuffleVectorInst::getShuffleMask(Mask, ShMask); SmallVector - NewVecC(VWidth, UndefValue::get(C->getType()->getScalarType())); + NewVecC(V1Width, UndefValue::get(C->getType()->getScalarType())); bool MayChange = true; for (unsigned I = 0; I < VWidth; ++I) { if (ShMask[I] >= 0) { - assert(ShMask[I] < (int)VWidth); + assert(ShMask[I] < (int)VWidth && "Not expecting narrowing shuffle"); Constant *CElt = C->getAggregateElement(I); Constant *NewCElt = NewVecC[ShMask[I]]; - if (!CElt || (!isa(NewCElt) && NewCElt != CElt)) { + // Bail out if: + // 1. The constant vector contains a constant expression. + // 2. The shuffle needs an element of the constant vector that can't + // be mapped to a new constant vector. + // 3. This is a widening shuffle that copies elements of V1 into the + // extended elements (extending with undef is allowed). + if (!CElt || (!isa(NewCElt) && NewCElt != CElt) || + I >= V1Width) { MayChange = false; break; } -- cgit v1.2.3