[llvm-branch-commits] [llvm] 821a51a - [X86][AVX] combineX86ShuffleChainWithExtract - widen to at least original root size. NFCI.

[Simon Pilgrim via llvm-branch-commits]

Author: Simon Pilgrim
Date: 2021-01-25T13:45:37Z
New Revision: 821a51a9cacfac7da8b34ccc0498d316471f1dbc

URL: https://github.com/llvm/llvm-project/commit/821a51a9cacfac7da8b34ccc0498d316471f1dbc
DIFF: https://github.com/llvm/llvm-project/commit/821a51a9cacfac7da8b34ccc0498d316471f1dbc.diff

LOG: [X86][AVX] combineX86ShuffleChainWithExtract - widen to at least original root size. NFCI.

We're relying on the source inputs for shuffle combining having already been widened to the root size (otherwise the offset logic falls over) - we're going to be supporting different sized shuffle inputs soon, so we need to explicitly make the minimum widened width the original root size.

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86ISelLowering.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index d2a07e7364dd..ae73a32a5d9a 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -35997,12 +35997,16 @@ static SDValue combineX86ShuffleChainWithExtract(
   if (NumInputs == 0)
     return SDValue();
 
+  EVT RootVT = Root.getValueType();
+  unsigned RootSizeInBits = RootVT.getSizeInBits();
+  assert((RootSizeInBits % NumMaskElts) == 0 && "Unexpected root shuffle mask");
+
   SmallVector<SDValue, 4> WideInputs(Inputs.begin(), Inputs.end());
   SmallVector<unsigned, 4> Offsets(NumInputs, 0);
 
   // Peek through subvectors.
   // TODO: Support inter-mixed EXTRACT_SUBVECTORs + BITCASTs?
-  unsigned WideSizeInBits = WideInputs[0].getValueSizeInBits();
+  unsigned WideSizeInBits = RootSizeInBits;
   for (unsigned i = 0; i != NumInputs; ++i) {
     SDValue &Src = WideInputs[i];
     unsigned &Offset = Offsets[i];
@@ -36025,8 +36029,6 @@ static SDValue combineX86ShuffleChainWithExtract(
   if (llvm::all_of(Offsets, [](unsigned Offset) { return Offset == 0; }))
     return SDValue();
 
-  EVT RootVT = Root.getValueType();
-  unsigned RootSizeInBits = RootVT.getSizeInBits();
   unsigned Scale = WideSizeInBits / RootSizeInBits;
   assert((WideSizeInBits % RootSizeInBits) == 0 &&
          "Unexpected subvector extraction");