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From: Ben Harris <bjh21@netbsd.org> To: nobody@gcc.gnu.org Cc: gcc-prs@gcc.gnu.org Subject: Re: optimization/4733: Incorrect code when aliasing double and struct on ARM -O2 Date: Mon, 29 Oct 2001 10:16:00 -0000 [thread overview] Message-ID: <20011029181604.4259.qmail@sourceware.cygnus.com> (raw) The following reply was made to PR optimization/4733; it has been noted by GNATS. From: Ben Harris <bjh21@netbsd.org> To: <Richard.Earnshaw@arm.com> Cc: <gcc-gnats@gcc.gnu.org> Subject: Re: optimization/4733: Incorrect code when aliasing double and struct on ARM -O2 Date: Mon, 29 Oct 2001 18:08:14 +0000 (GMT) On Mon, 29 Oct 2001, Richard Earnshaw wrote: > Nope, this code violates the ANSI memory aliasing rules. Ah yes, I'd tried -fno-strict-aliasing on 2.95.3, but not on 20011023. Thanks. > According to > ANSI, the only way to do this portably is to memcpy between the types; Yeah, that works. The code it produces isn't all that wonderful, though: ... mov r3, sp stmia r3, {r0-r1} ldmia r3, {r0, r1} add r2, sp, #8 stmia r2, {r0, r1} mov r2, #2032 ldrh r3, [sp, #14] @ movhi ... -- Ben Harris <bjh21@netbsd.org> Portmaster, NetBSD/arm26 <URL: http://www.netbsd.org/Ports/arm26/ >
next reply other threads:[~2001-10-29 10:16 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2001-10-29 10:16 Ben Harris [this message] -- strict thread matches above, loose matches on Subject: below -- 2002-02-04 13:29 toon 2001-10-29 9:56 Richard Earnshaw 2001-10-29 9:26 bjh21
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