[llvm] b375f28 - [X86][AVX] lowerShuffleAsLanePermuteAndSHUFP - only set the demanded elements of the lane mask.

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2020-01-12T09:41:40Z
New Revision: b375f28b0ec1129a4b94770a9c55ba49222ea1dd

URL: https://github.com/llvm/llvm-project/commit/b375f28b0ec1129a4b94770a9c55ba49222ea1dd
DIFF: https://github.com/llvm/llvm-project/commit/b375f28b0ec1129a4b94770a9c55ba49222ea1dd.diff

LOG: [X86][AVX] lowerShuffleAsLanePermuteAndSHUFP - only set the demanded elements of the lane mask.

Fixes an cyclic dependency issue with an upcoming patch where getVectorShuffle canonicalizes masks with splat build vector sources.

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 073b78b6ae67..c7a42b15cb0c 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -14907,8 +14907,7 @@ static SDValue lowerShuffleAsLanePermuteAndSHUFP(const SDLoc &DL, MVT VT,
       continue;
     int LaneBase = i & ~1;
     auto &LaneMask = (i & 1) ? RHSMask : LHSMask;
-    LaneMask[LaneBase + 0] = (M & ~1);
-    LaneMask[LaneBase + 1] = (M & ~1) + 1;
+    LaneMask[LaneBase + (M & 1)] = M;
     SHUFPMask |= (M & 1) << i;
   }