efriedma added a comment. The reason struct returns require register shuffling is that AArch64 passes the sret pointer in x8 (i.e. RAX), but the x64 calling convention expects in in RCX (i.e. x0).
Have you tried to see if the Microsoft-generated thunk actually works? I found at least one bug in MSVC thunk generation and reported it to Microsoft. (Microsoft didn't acknowledge the report, but that's a different story...) Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D125418/new/ https://reviews.llvm.org/D125418 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
