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

[Paul Walker via llvm-commits]

=?utf-8?q?Gaëtan?= Bossu <gaetan.bossu at arm.com>,
=?utf-8?q?Gaëtan?= Bossu <gaetan.bossu at arm.com>,
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=?utf-8?q?Gaëtan?= Bossu <gaetan.bossu at arm.com>,
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In-Reply-To: <llvm.org/llvm/llvm-project/pull/208212 at github.com>


================
@@ -8261,6 +8293,33 @@ SDValue DAGTypeLegalizer::WidenVecOp_CONCAT_VECTORS(SDNode *N) {
   return DAG.getBuildVector(VT, dl, Ops);
 }
 
+SDValue DAGTypeLegalizer::WidenVecOp_VECTOR_REPEAT(SDNode *N) {
+  SDLoc DL(N);
+  EVT VT = N->getValueType(0);
+  SDValue Src = N->getOperand(0);
+  EVT SrcVT = Src.getValueType();
+  EVT WidenedSrcVT = TLI.getTypeToTransformTo(*DAG.getContext(), SrcVT);
+
+  if (!WidenedSrcVT.getVectorElementCount().hasKnownScalarFactor(
+          SrcVT.getVectorElementCount()))
+    report_fatal_error(
+        "Cannot widen VECTOR_REPEAT operand to an ElementCount that's not "
+        "a multiple of the input ElementCount.");
+
+  // Repeat the original source because the extra lanes of its widened value
+  // are unspecified.
+  unsigned NumConcat =
+      WidenedSrcVT.getVectorElementCount().getKnownScalarFactor(
+          SrcVT.getVectorElementCount());
+  SmallVector<SDValue, 8> Ops(NumConcat, Src);
+  SDValue WidenedSrc = DAG.getNode(ISD::CONCAT_VECTORS, DL, WidenedSrcVT, Ops);
+  EVT WidenedVT = VT.changeVectorElementCount(
+      *DAG.getContext(),
+      ElementCount::getScalable(WidenedSrcVT.getVectorMinNumElements()));
----------------
paulwalker-arm wrote:

```suggestion
      ElementCount::getScalable(WidenedSrcVT.getVectorNumElements()));
```
At this point WidenedSrcVT must be a fixed-length vector. 

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