[X86] In lowerVectorShuffleAsBroadcast, make peeking through CONCAT_VECTORS work correctly if we already walked through a bitcast that changed the element size.

The CONCAT_VECTORS case was using the original mask element count to determine how to adjust the broadcast index. But if we looked through a bitcast the original mask size doesn't tell us anything about the concat_vectors.

This patch switchs to using the concat_vectors input element count directly instead.

Differential Revision: https://reviews.llvm.org/D53823

llvm-svn: 345626

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index da5340a050b..9acae2cab22 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -11238,7 +11238,8 @@ static SDValue lowerVectorShuffleAsBroadcast(const SDLoc &DL, MVT VT,
       continue;
     }
     case ISD::CONCAT_VECTORS: {
-      int OperandSize = Mask.size() / V.getNumOperands();
+      int OperandSize =
+          V.getOperand(0).getSimpleValueType().getVectorNumElements();
       V = V.getOperand(BroadcastIdx / OperandSize);
       BroadcastIdx %= OperandSize;
       continue;