[llvm] [VP] IR expansion for bitreverse/bswap (PR #68504)

[Simon Pilgrim via llvm-commits]

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@@ -702,7 +702,17 @@ Value *CachingVPExpander::expandPredication(VPIntrinsic &VPI) {
   case Intrinsic::vp_fneg: {
     Value *NewNegOp = Builder.CreateFNeg(VPI.getOperand(0), VPI.getName());
     replaceOperation(*NewNegOp, VPI);
-    return NewNegOp;  
+    return NewNegOp;
+  }
+  case Intrinsic::vp_bswap:
+  case Intrinsic::vp_bitreverse: {
+    Value *Op = VPI.getOperand(0);
+    Function *Fn = Intrinsic::getDeclaration(
+        VPI.getModule(), VPI.getFunctionalIntrinsicID().value(),
+        {VPI.getType()});
+    Value *NewOp = Builder.CreateCall(Fn, {Op}, VPI.getName());
+    replaceOperation(*NewOp, VPI);
+    return NewOp;
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RKSimon wrote:

Maybe worth moving this to expandPredicationToIntCall and adding unary handling?

https://github.com/llvm/llvm-project/pull/68504