[PATCH] D42090: [DAGCombiner] Add a DAG combine to turn a splat build_vector where the splat elemnt is a bitcast from a vector type into a concat_vector

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


================
Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:14953
+  if (SDValue Splat = cast<BuildVectorSDNode>(N)->getSplatValue()) {
+    if (Splat.getOpcode() == ISD::BITCAST) {
+      EVT SrcVT = Splat.getOperand(0).getValueType();
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spatel wrote:
> Might want to use 'peekThroughBitcast' here...although that reminds me that I still need to figure out if we can remove the loop in there yet.
I thought about that, but I would have to still verify that at least one bitcast had existed. My assumption is that if there were multiple bitcasts, they would be combined and cause this user to get re-evaluated right?


https://reviews.llvm.org/D42090