[llvm] 91720ee - [X86] combineX86ShufflesRecursively - fix use after move warning. NFCI.

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2020-09-20T14:06:50+01:00
New Revision: 91720ee561b2da4161df6abaddfd8a677aebb504

URL: https://github.com/llvm/llvm-project/commit/91720ee561b2da4161df6abaddfd8a677aebb504
DIFF: https://github.com/llvm/llvm-project/commit/91720ee561b2da4161df6abaddfd8a677aebb504.diff

LOG: [X86] combineX86ShufflesRecursively - fix use after move warning. NFCI.

After moving WidenedMask is in an undefined state, so reduce scope of the variable so its reinitialized every iteration - we should still retain any memory allocation savings.

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 6ad912892a73..3a4f09bc6c9f 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -36147,8 +36147,10 @@ static SDValue combineX86ShufflesRecursively(
     // elements, and shrink them to the half-width mask. It does this in a loop
     // so it will reduce the size of the mask to the minimal width mask which
     // performs an equivalent shuffle.
-    SmallVector<int, 64> WidenedMask;
-    while (Mask.size() > 1 && canWidenShuffleElements(Mask, WidenedMask)) {
+    while (Mask.size() > 1) {
+      SmallVector<int, 64> WidenedMask;
+      if (!canWidenShuffleElements(Mask, WidenedMask))
+        break;
       Mask = std::move(WidenedMask);
     }