[llvm] [IR][REVEC] Define llvm.vector.broadcast intrinsic (PR #208212)

[Gaëtan Bossu via llvm-commits]

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@@ -4019,6 +4072,13 @@ bool DAGTypeLegalizer::SplitVectorOperand(SDNode *N, unsigned OpNo) {
   return false;
 }
 
+SDValue DAGTypeLegalizer::SplitVecOp_VECTOR_BROADCAST(SDNode *N) {
+  SDLoc DL(N);
+  SDValue SrcLo, SrcHi;
+  GetSplitVector(N->getOperand(0), SrcLo, SrcHi);
+  return buildSplitVectorBroadcast(DAG, DL, N->getValueType(0), SrcLo, SrcHi);
+}
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gbossu wrote:

Sorry the code was really not clear... Basically, that's expected that the hi half is ignored. `buildSplitVectorBroadcast` will produce two VT results. If we were to concatenate them, we'd get the wrong destination type. I've added comments.

https://github.com/llvm/llvm-project/pull/208212