This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug middle-end/47602] Permit inline asm to clobber PIC register
- From: "ebotcazou at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 4 Feb 2011 15:23:33 +0000
- Subject: [Bug middle-end/47602] Permit inline asm to clobber PIC register
- Auto-submitted: auto-generated
- References: <bug-47602-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47602
--- Comment #13 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-02-04 15:23:22 UTC ---
> In what way are we helping them by forcing them to know about it? How does
> that help them write inline assembler which, e.g., uses the cpuid instruction,
> or makes a kernel system call which passes a parameter in %ebx?
In these cases, that won't probably help them indeed. But, in other cases,
like someone wanting to write very efficiently a hot loop in asm for a library,
making it explicit that the %ebx register is not freely available like the
others might help him to find the most efficient approach. Maybe we could just
warn though.