[X86][SSE] SimplifyDemandedVectorEltsForTargetNode - simplify PSHUFB masks

Attempt to simplify PSHUFB masks (even non-constant ones) - we should probably be able to simplify other variable shuffles as well as the need arises.

llvm-svn: 343919

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 02999f26d6c..cb4eea7d009 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -31755,6 +31755,15 @@ bool X86TargetLowering::SimplifyDemandedVectorEltsForTargetNode(
       return true;
     break;
   }
+  case X86ISD::PSHUFB: {
+    // TODO - simplify other variable shuffle masks.
+    SDValue Mask = Op.getOperand(1);
+    APInt MaskUndef, MaskZero;
+    if (SimplifyDemandedVectorElts(Mask, DemandedElts, MaskUndef, MaskZero, TLO,
+                                   Depth + 1))
+      return true;
+    break;
+  }
   }
 
   // Simplify target shuffles.