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Re: enabling -O2 with gcc 2.96 and later

To: "Martin v. Loewis" <martin at loewis dot home dot cs dot tu-berlin dot de>
Subject: Re: enabling -O2 with gcc 2.96 and later
From: Gabriel Dos Reis <gdr at sourceware dot cygnus dot com>
Date: 18 Dec 1999 01:28:30 +0100
Cc: oliva at lsd dot ic dot unicamp dot br, pedwards at jaj dot com, libstdc++ at sourceware dot cygnus dot com
Organization: None.
References: <199912171814.NAA05999@jaj.com> <oriu1xl6t2.fsf@benta.lsd.ic.unicamp.br> <199912172317.AAA01111@loewis.home.cs.tu-berlin.de>
Reply-To: libstdc++ at sourceware dot cygnus dot com

"Martin v. Loewis" <martin@loewis.home.cs.tu-berlin.de> writes:

| > No offense intended, but so is this second attempt, IMHO :-)
| > 
| > How about:
| > 
| > AC_EGREP_CPP([ok], [
| > #if (__GNUC__ == 2 && __GNUC_MINOR__ > 95) || __GNUC__ > 2
| > ok
| > #fi
| > ], [OPTLEVEL='-O2'], [OPTLEVEL=])
| > AC_SUBST(OPTLEVEL)
| 
| I did not follow this closely, but I think checking version numbers in
| autoconf is morally wrong. 

Please, can you expand on this?

| ... What is the reason not to use -O2 in
| earlier versions? Something is miscompiled? 

Compiling v-3 with gcc-2.95.2 -g -O2 produces an ICE.

-- Gaby

Follow-Ups:
- Re: enabling -O2 with gcc 2.96 and later
  - From: Alexandre Oliva
- Re: enabling -O2 with gcc 2.96 and later
  - From: Martin v. Loewis

References:
- enabling -O2 with gcc 2.96 and later
  - From: Phil Edwards
- Re: enabling -O2 with gcc 2.96 and later
  - From: Alexandre Oliva
- Re: enabling -O2 with gcc 2.96 and later
  - From: Martin v. Loewis

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