[PATCH] D60349: [COFF, ARM64] Fix ABI implementation of struct returns

[Oliver Stannard (Linaro) via Phabricator via cfe-commits]

ostannard requested changes to this revision.
ostannard added a comment.
This revision now requires changes to proceed.

The document you linked in the LLVM change (https://docs.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions?view=vs-2019#return-values) says that small POD types are returned directly in X0 or X0 and X1, but this looks like it will always return them indirectly. I think we also need to check the size of the type, and fall back the the plain C ABI for small types.



================
Comment at: lib/CodeGen/MicrosoftCXXABI.cpp:1060
+  // Note: The "inreg" attribute is used to signal that the struct return
+  // should be in X0.
+  bool sretInX0 = (CGM.getTarget().getTriple().getArch() ==
----------------
Nit: this will use X1 for functions with a this parameter, not X0.


================
Comment at: lib/CodeGen/MicrosoftCXXABI.cpp:1062
+  bool sretInX0 = (CGM.getTarget().getTriple().getArch() ==
+                   llvm::Triple::aarch64) && !RD->isPOD();
+
----------------
This should also check aarch64_be.


Repository:
  rC Clang

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  https://reviews.llvm.org/D60349/new/

https://reviews.llvm.org/D60349