[PATCH] D25524: [DAGCombine] Preserve shuffles when one of the vector operands is constant

[Simon Pilgrim via llvm-commits]

RKSimon added inline comments.


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Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:7754
         return SDValue(Op.getOperand(0));
-      if (ISD::isBuildVectorOfConstantSDNodes(Op.getNode()) ||
-          ISD::isBuildVectorOfConstantFPSDNodes(Op.getNode()))
+      if (isAnyConstantBuildVector(Op.getNode()))
         return DAG.getBitcast(VT, Op);
----------------
If possible, do this change (along with the addition of isAnyConstantBuildVector) as a separate NFC pre-commit?


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Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:13936
   // BUILD_VECTOR or SCALAR_TO_VECTOR into a single BUILD_VECTOR.
   if (Level < AfterLegalizeVectorOps && TLI.isTypeLegal(VT)) {
+    if (SDValue Res = combineShuffleOfScalars(SVN, DAG, TLI))
----------------
Remove the outer braces to match style guide.


Repository:
  rL LLVM

https://reviews.llvm.org/D25524