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Date: Fri, 28 Mar 2003 22:26:00 -0000
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From: Falk Hueffner <falk.hueffner@student.uni-tuebingen.de>
Subject: Re: optimization/10258: byteswapping code fails in -O2
Reply-To: Falk Hueffner <falk.hueffner@student.uni-tuebingen.de>
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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