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Re: [PATCH] Omit frame pointer and fix %ebp by default on x86 (take 3)
- From: "Giovanni Bajo" <giovannibajo at libero dot it>
- To: "Roger Sayle" <roger at eyesopen dot com>
- Cc: <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 16 Aug 2004 03:35:56 +0200
- Subject: Re: [PATCH] Omit frame pointer and fix %ebp by default on x86 (take 3)
- References: <Pine.LNX.4.44.0408151758510.8952-100000@www.eyesopen.com>
Roger Sayle wrote:
> The second point is that we update both fixed_regs and call_used_regs.
> The cause of the failures mentioned above is caused by the fact that
> reload assumes that call_used_regs is a superset of fixed_regs, and
> so just modifying fixed_regs leads to a few additional testsuite
> failures.
So, why don't you add a runtime sanity check in debug builds so that others
won't be fooled by this?
See also: http://gcc.gnu.org/ml/gcc-patches/2004-06/msg00247.html, which was
submitted after a subtle miscompilation that took weeks to be isolated and
fixed.
Giovanni Bajo