----- Original Message -----
> From: "Jan Stancek" <[email protected]>
> To: [email protected]
> Cc: [email protected]
> Sent: Thursday, 21 August, 2014 4:45:10 PM
> Subject: Re: [LTP] [PATCH/RFC] profil01: don't use address of function
> > If we are in doubt, we should add a configure check and use it only when
> > available. And probably to default to &test_profil in all cases but
> > ppc64 BE which is known to fail.
>
> I'm trying one other idea:
>
> +static inline void *get_pc(void)
> +{
> + extern void *profil01_label;
> +
> + asm("profil01_label:");
> + return &profil01_label;
> +}
>
Both ways seem to work fine at least since gcc-4.1, and very first clang
released in LLVM 2.6 [1]:
# cat getpc.c
#include <stdio.h>
static inline void *get_pc(void)
{
extern void *profil01_label;
asm("profil01_label:");
return &profil01_label;
}
static void __attribute__ ((noinline)) *get_pc_gcc(void)
{
return __builtin_return_address(0);
}
int main()
{
printf("%p %p %p\n", get_pc(), get_pc_gcc(), &main);
}
# ./clang/llvm+clang-2.6-x86_64-linux/bin/clang -O2 getpc.c
# ./a.out
0x400534 0x400539 0x400530
Regards,
Jan
[1] http://llvm.org/releases/2.6/docs/ReleaseNotes.html
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