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From: Falk Hueffner <falk.hueffner@student.uni-tuebingen.de>
To: nobody@gcc.gnu.org
Cc: gcc-prs@gcc.gnu.org,
Subject: Re: optimization/10258: byteswapping code fails in -O2
Date: Fri, 28 Mar 2003 22:26:00 -0000	[thread overview]
Message-ID: <20030328221600.24971.qmail@sources.redhat.com> (raw)

The following reply was made to PR optimization/10258; it has been noted by GNATS.

From: Falk Hueffner <falk.hueffner@student.uni-tuebingen.de>
To: warren_baird@cimmetry.com
Cc: gcc-gnats@gcc.gnu.org
Subject: Re: optimization/10258: byteswapping code fails in -O2
Date: 28 Mar 2003 23:15:44 +0100

 warren_baird@cimmetry.com writes:
 
 > FLOAT swapFLOAT(FLOAT f)
 > {
 > 	FLOAT ret;
 > 	DWORD* pDW = (DWORD*)&ret;
 > 	*pDW = BYTESWAP_DWORD(*(DWORD*)&f);
 
 You're violating aliasing constraints here
 
 > 	printf("0x%08X 0x%08X\n", *(long *)&f1, *(long *)&sf1);
 
 and here. So this is not a gcc bug. Please read the documentation of
 -fstrict-aliasing.
 
 -- 
 	Falk


             reply	other threads:[~2003-03-28 22:16 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-03-28 22:26 Falk Hueffner [this message]
  -- strict thread matches above, loose matches on Subject: below --
2003-03-31 17:20 bangerth
2003-03-31 16:26 Warren_Baird
2003-03-28 22:16 bangerth
2003-03-28 22:14 warren_baird

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