[llvm] f611158 - [SelectionDAG] Better ISD::ANY_EXTEND/ISD::ANY_EXTEND_VECTOR_INREG ComputeKnownBits support

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2020-01-17T11:37:58Z
New Revision: f61115835085fb8a563091f9bbc1c2e7fc5425c2

URL: https://github.com/llvm/llvm-project/commit/f61115835085fb8a563091f9bbc1c2e7fc5425c2
DIFF: https://github.com/llvm/llvm-project/commit/f61115835085fb8a563091f9bbc1c2e7fc5425c2.diff

LOG: [SelectionDAG] Better ISD::ANY_EXTEND/ISD::ANY_EXTEND_VECTOR_INREG ComputeKnownBits support

Add DemandedElts handling to ISD::ANY_EXTEND and add missing ISD::ANY_EXTEND_VECTOR_INREG handling. Despite the lack of test changes this code IS being used - its just that the ANY_EXTEND ops are legalized later on (typically to ZERO_EXTEND equivalents) so we typically manage to combine later on.

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 313e07b5fdd6..1522075c67f8 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3099,8 +3099,15 @@ KnownBits SelectionDAG::computeKnownBits(SDValue Op, const APInt &DemandedElts,
     Known = Known.sext(BitWidth);
     break;
   }
+  case ISD::ANY_EXTEND_VECTOR_INREG: {
+    EVT InVT = Op.getOperand(0).getValueType();
+    APInt InDemandedElts = DemandedElts.zextOrSelf(InVT.getVectorNumElements());
+    Known = computeKnownBits(Op.getOperand(0), InDemandedElts, Depth + 1);
+    Known = Known.zext(BitWidth, false /* ExtendedBitsAreKnownZero */);
+    break;
+  }
   case ISD::ANY_EXTEND: {
-    Known = computeKnownBits(Op.getOperand(0), Depth+1);
+    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
     Known = Known.zext(BitWidth, false /* ExtendedBitsAreKnownZero */);
     break;
   }