bcl5980 added a comment. In D125418#3759174 <https://reviews.llvm.org/D125418#3759174>, @efriedma wrote:
> 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). So, for the function: s64 f(int a): AArch64 CC: void f(x8, x0) X64 CC: void f(rcx[x0], rdx[x1]) AArch64 --> X64 we need to add instructions before blr mov x1, x0 mov x0, x8 It can match `iexit_thunk$cdecl$m64$i8` when we call extern function not a function pointer. > 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...) You are right. For now, I haven't tested too much case runtime. But it looks if a DLL import function pass to a function pointer, then call it will cause access violation. Based on the debug result, it should be exit thunk issue, MSVC generate wrong thunk type. 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
