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Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
From: |
Paul Eggert |
Subject: |
Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..." |
Date: |
Sat, 30 Dec 2006 22:08:57 -0800 |
User-agent: |
Gnus/5.1008 (Gnus v5.10.8) Emacs/21.4 (gnu/linux) |
Robert Dewar <address@hidden> writes:
> Of course there is a way out that satisfies both
> sides here, and that is to declare that gcc code
> should adhere to the standard *including* LIA
> and then make sure the default mode of gcc is
> LIA compliant.
Yes, this should solve the problem. The idea is that -O2
would assume wrapv semantics. It's fine with me if higher
optimization levels disable -fwrapv by default.
As I understand it the principal argument against this
change is that the performance of some numeric programs
would be adversely affected. But like you, I doubt whether
it'd affect GCC's performance much, nor would it much affect
the performance of glibc, coreutils, etc., etc.
Also, as I understand it this change shouldn't affect gcc's
SPEC benchmark scores, since they're typically done with -O3
or better.
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", (continued)
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Kenner, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Vincent Lefevre, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Robert Dewar, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Kenner, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Robert Dewar, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Vincent Lefevre, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Kenner, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Robert Dewar, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Gabriel Dos Reis, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Robert Dewar, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...",
Paul Eggert <=
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Steven Bosscher, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Paul Eggert, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Kenner, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Robert Dewar, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Kenner, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Robert Dewar, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Daniel Berlin, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Guenther, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Daniel Berlin, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Paul Eggert, 2006/12/31