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From: "krebbel at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug libffi/56033] FAIL: libffi.call/cls_struct_va1.c on powerpc-*-* and sparc-sun-solaris2* with -m64
Date: Mon, 08 Apr 2013 11:19:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56033

Andreas Krebbel <krebbel at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |krebbel at gcc dot gnu.org

--- Comment #5 from Andreas Krebbel <krebbel at gcc dot gnu.org> 2013-04-08 11:19:16 UTC ---
Confirmed for s390x.

Looks like an endianess issue to me. In cls_struct_va1.c the void pointer to
the return value is cast to an int pointer before writing to it:

static void
test_fn (ffi_cif* cif __UNUSED__, void* resp,
     void** args, void* userdata __UNUSED__)
{
...
  * (int*) resp = 42;
}

But the pointer later on is expected to point to a register size value.

There are also testcases which do it differently (e.g. closure_fn0.c). They
cast the pointer to the return value to ffi_arg* before accessing it. ffi_arg
is defined to be a register size type. From the documentation I cannot tell
which one is supposed to be correct.

static void
closure_test_fn0(ffi_cif* cif __UNUSED__, void* resp, void** args,
         void* userdata)
{
  *(ffi_arg*)resp = ...
}

Btw. for both examples the return type is defined as &ffi_type_sint in
ffi_prep_cif