[PATCH] D104187: [DAGCombine] reduceBuildVecToShuffle(): sort input vectors by decreasing size

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added a comment.

A few nits but the premise seems sound - did you encounter real world cases that led you to this?



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Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:19121
+      } else {
+        assert(InVT2Size <= InVT1Size);
         // VecIn1 is wider than the output, and we have another, possibly
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assert message


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Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:19270
+  return std::distance(Range.begin(), I);
+}
+
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Move this inside reduceBuildVecToShuffle?


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Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:19416
+    unsigned Idx = getFirstIndexOf(SortedVecIn, VecIn[SourceVectorIndex]);
+    assert(Idx > 0 && Idx < SortedVecIn.size());
+    assert(VecIn[SourceVectorIndex] == SortedVecIn[Idx] && "Remapping failure");
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assert message (or merge asserts)


Repository:
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  https://reviews.llvm.org/D104187/new/

https://reviews.llvm.org/D104187