This is test code for the bug:

long long __divdi3(long long a, long long b)
{
        return a + b;
}

f()
{
        volatile int x = 1;
        long long a1 = 4, a2 = 2;
        /*long long a = __divdi3(a1, a2);*/
        long long a = a1 / a2;
        if (x != 1) abort();
        return a;
}

main()
{
        return f();
}

compile it with -fomit-frame-pointer -mrtd flags. When you run it, it fails in Abort function, because value of variable `x' changed because stack pointer is incorrect in function f.

When you look at assembler, you see that __divdi3 exits with ret $16 and there's additional addl $16, %esp after calling __divdi3.

Mikulas

I can confirm this on the mainline (20030805).

Most likely the same bug as PR 12769.

There's a similar issue with trying to override certain builtins calling convention with -mrtd in effect.  Consider

 extern void* __attribute__((__cdecl__)) memcpy(void*, void*, __SIZE_TYPE__);

we even after seeing this decl emit calls to memcpy with -mrtd ABI out of
emit_block_move_via_libcall.

*** Bug 22017 has been marked as a duplicate of this bug. ***

Author: ktietz
Date: Mon Apr 11 17:44:04 2011
New Revision: 172268

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=172268
Log:
2011-04-11  Kai Tietz  <ktietz@redhat.com>

	PR target/9601
	PR target/11772
	* config/i386/i386-protos.h (ix86_get_callcvt): New prototype.
	* config/i386/i386.c (ix86_handle_cconv_attribute): Adjust
	comment.
	(ix86_is_msabi_thiscall): Removed.
	(ix86_is_type_thiscall): Likewise.
	(ix86_get_callcvt): New function.
	(ix86_comp_type_attributes): Simplify check.
	(ix86_function_regparm): Use ix86_get_callcvt for calling
	convention attribute checks.
	(ix86_return_pops_args): Likewise.
	(ix86_static_chain): Likewise.
	(x86_this_parameter): Likewise.
	(x86_output_mi_thunk): Likewise.
	(ix86_function_type_abi): Optimize check for types without attributes.
	* config/i386/i386.h (IX86_CALLCVT_CDECL, IX86_CALLCVT_STDCALL,
	IX86_CALLCVT_FASTCALL, IX86_CALLCVT_THISCALL, IX86_CALLCVT_REGPARM,
	IX86_CALLCVT_SSEREGPARM): New macros to represent calling convention
	by flag-values.
	(IX86_BASE_CALLCVT): Helper macro.
	* config/i386/netware.c (i386_nlm_maybe_mangle_decl_assembler_name):
	Use ix86_get_callcvt for calling convention attribute checks and avoid
	symbol-decoration for stdcall in TARGET_RTD case.
	* config/i386/winnt.c (i386_pe_maybe_mangle_decl_assembler_name):
	Likewise.
	(gen_stdcall_or_fastcall_suffix): Adjust ident and use DECL_ORIGIN
	for declaration.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/i386/i386-protos.h
    trunk/gcc/config/i386/i386.c
    trunk/gcc/config/i386/i386.h
    trunk/gcc/config/i386/netware.c
    trunk/gcc/config/i386/winnt.c

Fixed.