Good evening, Jay.
2011/1/12 Jay Cornwall <jay at jcornwall.me.uk>:> Hi,
>
> I've encountered a problem invoking LLVM-generated x86_64 code on
> Windows from MSVC-compiled code. There seems to be disagreement between
> the two compilers over the calling convention for passing a 12 or 16
> byte structure by value. e.g.
>
> struct aggregate { int a; int b; int c; int d; };
> int test(aggregate byVal) { ... }
>
> LLVM chooses to pass byVal with a and b packed into rcx and c and d
> packed into rdx. MSVC (8 here) instead passes a reference to the
> structure in rcx. My reading of the System V ABI spec is unclear,
> although Microsoft already deviate in their choice of fastcall registers
> so perhaps it is irrelevant.
I guess it might be a clang's issue.
ToT clang does not know Win64 calling conversion and it seems you saw
"amd64-like" cc.
> Should I file a bug for this?
You may file one though I have patches for it.
I will post patches for clang soon.
...Takumi