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[Bug libstdc++/5625] [mips] exception unwinding creates invalid pointer on mips
- From: "cgd at broadcom dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 5 Feb 2004 06:25:19 -0000
- Subject: [Bug libstdc++/5625] [mips] exception unwinding creates invalid pointer on mips
- References: <20020207120601.5625.emaste@sandvine.com>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From cgd at broadcom dot com 2004-02-05 06:25 -------
Subject: Re: [mips] exception unwinding creates
invalid pointer on mips
At 5 Feb 2004 02:45:07 -0000, wilson at gcc dot gnu dot org wrote:
> This patch changes the MIPS backend to use DImode for Pmode when generating
> 64-bit ILP32 code, instead of SImode as it currently does.
I'm a bit concerned about this comment, because SImode values in
registers on MIPS should be in their properly sign-extended forms.
If they aren't, patterns like addsi3 (-> addu) will not work properly
under all conditions. (addu and other 32-bit arithmetic ops are
UNPREDICTABLE if operands don't have bits 63:32 matching bit 31, i.e.,
if they're not sign extended. mipsisa64 sim should be reporting that,
as I believe you've noticed.)
Sorry if i manage to help get bug closed prematurely. That's what
happens when a PHB tries to do real work. 8-)
chris
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=5625