[PATCH] D92762: [clang][AArch64][SVE] Avoid going through memory for coerced VLST arguments

[Cullen Rhodes via Phabricator via cfe-commits]

c-rhodes added inline comments.


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Comment at: clang/lib/CodeGen/CGCall.cpp:2671-2673
+      // See if this is a VLST coerced to a VLAT at the function boundary and
+      // the types match up. If so, use llvm.experimental.vector.extract to
+      // perform the conversion.
----------------
this is slightly confusing since the coercion done in TargetInfo is from fixed -> scalable so VLSTs are represented as scalable vectors in functions args/return, yet this is casting back to fixed in the function prolog using `llvm.experimental.vector.extract` like you mention in the commit message, could this comment clarify that?


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Comment at: clang/lib/CodeGen/CGCall.cpp:2674
+      // perform the conversion.
+      if (Ty->getAs<VectorType>()) {
+        auto *Coerced = Fn->getArg(FirstIRArg);
----------------
Do we want to check `VT->getVectorKind() == VectorType::SveFixedLengthDataVector` and `isa<llvm::ScalableVectorType>(Coerced->getType());`?


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Comment at: clang/lib/CodeGen/CGCall.cpp:2681
+            VecTyFrom->getElementType() == VecTyTo->getElementType()) {
+          llvm::Value *Zero = llvm::Constant::getNullValue(this->CGM.Int64Ty);
+
----------------
`this->` can be dropped?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D92762/new/

https://reviews.llvm.org/D92762