[PATCH] D120553: [DAG] SelectionDAG::isSplatValue - add initial BITCAST handling

[Phoebe Wang via Phabricator via llvm-commits]

pengfei added a comment.

The IR in the tests neither shows bitcast nor small element vector. Are they generated during the lowering? Do we have specific tests for the patch?



================
Comment at: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:2645
+    unsigned SrcBitWidth = SrcVT.getScalarSizeInBits();
+    unsigned BitWidth = V.getScalarValueSizeInBits();
+
----------------
nit: `VT.getScalarSizeInBits()`


================
Comment at: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:2652
+
+    if (BitWidth == SrcBitWidth)
+      return isSplatValue(Src, DemandedElts, UndefElts, Depth + 1);
----------------
Why do we need a bitcast if both `SrcVT` and `VT` are integer and have the same width? Don't `SrcVT == VT`?


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https://reviews.llvm.org/D120553