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

[Benjamin Maxwell via llvm-commits]

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


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@@ -17583,6 +17603,52 @@ SDValue AArch64TargetLowering::LowerEXTRACT_SUBVECTOR(SDValue Op,
   return SDValue();
 }
 
+SDValue AArch64TargetLowering::LowerVECTOR_BROADCAST(SDValue Op,
+                                                     SelectionDAG &DAG) const {
+  SDLoc DL(Op);
+  EVT VT = Op.getValueType();
+  assert(VT.isScalableVector() &&
+         "Custom lowering expected for scalable vectors only.");
+
+  if (isPackedVectorType(VT, DAG)) {
+    SDValue Src = Op.getOperand(0);
+    EVT SrcVT = Src.getValueType();
+    if (ElementCount::isKnownGE(VT.getVectorElementCount(),
+                                SrcVT.getVectorElementCount()))
+      return Op;
----------------
MacDue wrote:

nit: Add a comment that this is legal (and uses the ISEL patterns). 

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