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From: Zack Weinberg <zack@codesourcery.com>
To: martin@xemacs.org
Cc: gcc@gcc.gnu.org
Subject: Re: More embarrassing failures to optimize
Date: Sun, 05 Jan 2003 18:51:00 -0000	[thread overview]
Message-ID: <87of6vh233.fsf@egil.codesourcery.com> (raw)
In-Reply-To: <15895.61324.872456.502039@wobble.local> (Martin Buchholz's message of "Sun, 5 Jan 2003 00:40:44 -0800")

Martin Buchholz <martin@xemacs.org> writes:

> void f3 ()
> {
>   Bool t (true), f (false);
>
>   assert (t); assert (! f);
>   assert (t); assert (! f);
> }
>
> is "optimized" to
>
> 	xorl	%edx, %edx
> 	subl	$12, %esp
> 	testb	%dl, %dl
> 	jne	.L52
> 	addl	$12, %esp
> 	ret
> .L52:
> 	pushl	$_ZZ2f3vE19__PRETTY_FUNCTION__
> 	pushl	$42
> 	pushl	$.LC0
> 	pushl	$.LC2
> 	call	__assert_fail
>
> Note that the resulting code contains exactly one branch, not two or
> four.

I suspect this is the same underlying problem that causes
gcc.c-torture/execute/builtin-constant.c to fail.  This was discussed
at some length in the thread starting at
http://gcc.gnu.org/ml/gcc-patches/2002-11/msg00235.html - it's
nontrivial to fix.

You might want to try these embarrassing failures against the tree-ssa
branch.

zw

  reply	other threads:[~2003-01-05 18:41 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-01-05 10:44 Martin Buchholz
2003-01-05 18:51 ` Zack Weinberg [this message]
2003-01-05 23:01   ` Martin Buchholz
2003-01-05 23:11     ` Zack Weinberg

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