From a0069ba0dbe797ae18354cdd00d84e40f68fb97d Mon Sep 17 00:00:00 2001 From: Simon Pilgrim Date: Sat, 12 Jan 2019 16:38:56 +0000 Subject: [PATCH] [X86] More aggressive shuffle mask widening in combineExtractWithShuffle Use demanded extract index to set most of the shuffle mask to undef, making it easier to widen and peek through. llvm-svn: 351013 --- llvm/lib/Target/X86/X86ISelLowering.cpp | 9 +++++++++ llvm/test/CodeGen/X86/and-load-fold.ll | 3 +-- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index 06802aac81e5..843d28758320 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -33691,6 +33691,15 @@ static SDValue combineExtractWithShuffle(SDNode *N, SelectionDAG &DAG, scaleShuffleMask(Scale, Mask, ScaledMask); Mask = std::move(ScaledMask); } else if ((Mask.size() % NumSrcElts) == 0) { + // Simplify Mask based on demanded element. + int ExtractIdx = (int)N->getConstantOperandVal(1); + int Scale = Mask.size() / NumSrcElts; + int Lo = Scale * ExtractIdx; + int Hi = Scale * (ExtractIdx + 1); + for (int i = 0, e = (int)Mask.size(); i != e; ++i) + if (i < Lo || Hi <= i) + Mask[i] = SM_SentinelUndef; + SmallVector WidenedMask; while (Mask.size() > NumSrcElts && canWidenShuffleElements(Mask, WidenedMask)) diff --git a/llvm/test/CodeGen/X86/and-load-fold.ll b/llvm/test/CodeGen/X86/and-load-fold.ll index 27520f88a3ff..367ef2a344a6 100644 --- a/llvm/test/CodeGen/X86/and-load-fold.ll +++ b/llvm/test/CodeGen/X86/and-load-fold.ll @@ -7,8 +7,7 @@ define i8 @foo(<4 x i8>* %V) { ; CHECK-LABEL: foo: ; CHECK: # %bb.0: ; CHECK-NEXT: movd {{.*#+}} xmm0 = mem[0],zero,zero,zero -; CHECK-NEXT: punpcklbw {{.*#+}} xmm0 = xmm0[0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7] -; CHECK-NEXT: pextrw $2, %xmm0, %eax +; CHECK-NEXT: pextrw $1, %xmm0, %eax ; CHECK-NEXT: andb $95, %al ; CHECK-NEXT: # kill: def $al killed $al killed $eax ; CHECK-NEXT: retq