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Re: -O2 bug in gcc 3.2, 3.3 and 3.4 with 64 bit integers on x86

From: Andreas Schwab <schwab at suse dot de>
To: Anders Torger <torger at ludd dot luth dot se>
Cc: gcc-bugs at gcc dot gnu dot org
Date: Tue, 09 Nov 2004 17:26:59 +0100
Subject: Re: -O2 bug in gcc 3.2, 3.3 and 3.4 with 64 bit integers on x86
References: <200411091642.01430.torger@ludd.luth.se><je1xf39ft5.fsf@sykes.suse.de><200411091715.39696.torger@ludd.luth.se>

Anders Torger <torger@ludd.luth.se> writes:

> Compiler makes same mistake

Fix your code.

> the only difference is the warning

Which is the whole point.  Your example is violating the strict aliasing
rules and thus invoking undefined behaviour.

http://gcc.gnu.org/onlinedocs/gcc-3.4.3/gcc/Optimize-Options.html#index-fstrict_002daliasing-422

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
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"And now for something completely different."

Follow-Ups:
- Re: -O2 bug in gcc 3.2, 3.3 and 3.4 with 64 bit integers on x86
  - From: Anders Torger

References:
- -O2 bug in gcc 3.2, 3.3 and 3.4 with 64 bit integers on x86
  - From: Anders Torger
- Re: -O2 bug in gcc 3.2, 3.3 and 3.4 with 64 bit integers on x86
  - From: Andreas Schwab
- Re: -O2 bug in gcc 3.2, 3.3 and 3.4 with 64 bit integers on x86
  - From: Anders Torger

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