>Number:         22313
>Category:       bin
>Synopsis:       gcc3 fails with -O2 and bswap64()
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jul 31 02:29:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     Geoff C. Wing
>Release:        NetBSD 1.6U
>Organization:
>Environment:
System: NetBSD g.primenet.com.au 1.6U NetBSD 1.6U (G) #0: Mon Jul 28 12:42:54 EST 2003 gcw@g.primenet.com.au:/usr/netbsd/src/sys/arch/i386/compile/G i386
Architecture: i386
Machine: i386
>Description:
	gcc 3.3.1 20030720 (prerelease) fails in optimising mixed 32 & 64 bit
	data types on i386

	% fortune
	!07/11 PDP a ni deppart m'I  !pleH
	% fortune
	!07/11 PDP a ni deppart m'I  !pleH

	Seems to be caused by -fstrict-aliasing

	Using -O1 and the other flags specified in the -O2 section of the
	manual works.


>How-To-Repeat:

------------------------------------------------------------
#include <stdio.h>
#include <sys/types.h>
#include <machine/bswap.h>

u_int64_t a_bswap64(u_int64_t);	/* copy of bswap64() function */

main()
{
  u_int64_t a;
  u_int8_t *b = (u_int8_t *)(void *)&a;
  int i;

  a = bswap64(1);
  printf("%lld\n", a);
  for (i = 0; i < sizeof(a) / sizeof(u_int8_t); i++)
	printf("%d:%d\n", i, b[i]);
}

u_int64_t
a_bswap64(x)
u_int64_t x;
{
	u_int32_t *p = (u_int32_t*)(void *)&x;
	u_int32_t t;

	t = bswap32(p[0]);
	p[0] = bswap32(p[1]);
	p[1] = t;
	return x;
}
------------------------------------------------------------

>Fix:
	?
>Release-Note:
>Audit-Trail:
>Unformatted: