Date: Mon, 11 Nov 2002 21:41:42 +0900 From: TOMITA Yoshinori <yoshint@flab.fujitsu.co.jp> To: FreeBSD-current@FreeBSD.ORG Subject: gcc 3.2.1 optimization bug ? Message-ID: <ywlvg34jn21.fsf@cerberus.proc.flab.fujitsu.co.jp>
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For the source code below, compiling gcc -O2/-O3 seem to produce
incorrect code.
-----------------------------------
#include <stdio.h>
int main(int argc, char* argv[])
{
unsigned int x = 0x12345678;
unsigned short tmp;
printf("%x\n", x);
tmp = ((unsigned short *)&x)[0];
((unsigned short *)&x)[0] = ((unsigned short *)&x)[1];
((unsigned short *)&x)[1] = tmp;
printf("%x\n", x);
return 0;
}
-----------------------------------
% gcc -O1 a.c
% ./a.out
12345678
56781234
% gcc -O2 a.c
% ./a.out
12345678
12341234
% gcc -v
Using built-in specs.
Configured with: FreeBSD/i386 system compiler
Thread model: posix
gcc version 3.2.1 [FreeBSD] 20021009 (prerelease)
Is this a gcc bug or the source code problem ?
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