From a807aae2265fcbea4a04290c8dd739fe02dc1bea Mon Sep 17 00:00:00 2001 From: Eli Friedman Date: Sat, 18 Jul 2009 09:07:47 +0000 Subject: [PATCH] Canonicalize insert/extractelement from single-element vectors into bitcasts. It would also be possible to canonicalize the other way; does anyone have a preference? llvm-svn: 76300 --- .../Scalar/InstructionCombining.cpp | 22 ++++++++++++++----- .../Transforms/InstCombine/vec-single-elt.ll | 12 ++++++++++ 2 files changed, 28 insertions(+), 6 deletions(-) create mode 100644 llvm/test/Transforms/InstCombine/vec-single-elt.ll diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp index 060abc5ad085..0a5fc80952bd 100644 --- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp @@ -12366,13 +12366,18 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) { if (op0) return ReplaceInstUsesWith(EI, op0); } - + + unsigned VectorWidth = + cast(EI.getOperand(0)->getType())->getNumElements(); + + // Canonicalize extractelement from a vector of width 1 to a bitcast + if (VectorWidth == 1) + return new BitCastInst(EI.getOperand(0), EI.getType()); + // If extracting a specified index from the vector, see if we can recursively // find a previously computed scalar that was inserted into the vector. if (ConstantInt *IdxC = dyn_cast(EI.getOperand(1))) { unsigned IndexVal = IdxC->getZExtValue(); - unsigned VectorWidth = - cast(EI.getOperand(0)->getType())->getNumElements(); // If this is extracting an invalid index, turn this into undef, to avoid // crashing the code below. @@ -12382,7 +12387,7 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) { // This instruction only demands the single element from the input vector. // If the input vector has a single use, simplify it based on this use // property. - if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) { + if (EI.getOperand(0)->hasOneUse()) { APInt UndefElts(VectorWidth, 0); APInt DemandedMask(VectorWidth, 1 << IndexVal); if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0), @@ -12619,13 +12624,18 @@ Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) { // Inserting an undef or into an undefined place, remove this. if (isa(ScalarOp) || isa(IdxOp)) ReplaceInstUsesWith(IE, VecOp); - + + unsigned NumVectorElts = IE.getType()->getNumElements(); + + // Canonicalize insertelement into vector of width 1 to a bitcast + if (NumVectorElts == 1) + return new BitCastInst(IE.getOperand(1), IE.getType()); + // If the inserted element was extracted from some other vector, and if the // indexes are constant, try to turn this into a shufflevector operation. if (ExtractElementInst *EI = dyn_cast(ScalarOp)) { if (isa(EI->getOperand(1)) && isa(IdxOp) && EI->getOperand(0)->getType() == IE.getType()) { - unsigned NumVectorElts = IE.getType()->getNumElements(); unsigned ExtractedIdx = cast(EI->getOperand(1))->getZExtValue(); unsigned InsertedIdx = cast(IdxOp)->getZExtValue(); diff --git a/llvm/test/Transforms/InstCombine/vec-single-elt.ll b/llvm/test/Transforms/InstCombine/vec-single-elt.ll new file mode 100644 index 000000000000..45bca42c3e01 --- /dev/null +++ b/llvm/test/Transforms/InstCombine/vec-single-elt.ll @@ -0,0 +1,12 @@ +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep element +; insert/extractelement should canonicalize to bitcast + +define i64 @a(<1 x i64> %x) { + %r = extractelement <1 x i64> %x, i32 0 + ret i64 %r +} + +define <1 x i64> @b(i64 %x) { + %r = insertelement <1 x i64> undef, i64 %x, i32 0 + ret <1 x i64> %r +}