* [PATCH] Update changes.html about -Wno-aggressive-loop-optimizations
@ 2013-03-22 10:28 Jakub Jelinek
2013-03-22 10:34 ` Richard Biener
0 siblings, 1 reply; 2+ messages in thread
From: Jakub Jelinek @ 2013-03-22 10:28 UTC (permalink / raw)
To: Richard Biener; +Cc: gcc-patches
Hi!
This new warning switch hasn't been mentioned in changes.html, the following
patch fixes that. Is this ok, or do you have better wording?
--- htdocs/gcc-4.8/changes.html 14 Mar 2013 01:13:56 -0000 1.108
+++ htdocs/gcc-4.8/changes.html 22 Mar 2013 10:22:37 -0000
@@ -32,7 +32,12 @@ the number of iterations of loops using
standards. This may cause non-conforming programs to no longer work as
expected, such as SPEC CPU 2006 464.h264ref and 416.gamess. A new
option, <code>-fno-aggressive-loop-optimizations</code>, was added
-to disable this aggressive analysis.</p>
+to disable this aggressive analysis. In some loops that have known
+constant number of iterations, but undefined behavior is known to occur
+in the loop before reaching or during the last iteration, GCC will warn
+about the undefined behavior in the loop instead of deriving lower upper
+bound of the number of iterations for the loop. The warning
+can be disabled with <code>-Wno-aggressive-loop-optimizations</code>.</p>
<p>On ARM, a bug has been fixed in GCC's implementation of the AAPCS
rules for the layout of vectors that could lead to wrong code being
Jakub
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] Update changes.html about -Wno-aggressive-loop-optimizations
2013-03-22 10:28 [PATCH] Update changes.html about -Wno-aggressive-loop-optimizations Jakub Jelinek
@ 2013-03-22 10:34 ` Richard Biener
0 siblings, 0 replies; 2+ messages in thread
From: Richard Biener @ 2013-03-22 10:34 UTC (permalink / raw)
To: Jakub Jelinek; +Cc: gcc-patches
On Fri, 22 Mar 2013, Jakub Jelinek wrote:
> Hi!
>
> This new warning switch hasn't been mentioned in changes.html, the following
> patch fixes that. Is this ok, or do you have better wording?
No, looks ok to me.
Richard.
> --- htdocs/gcc-4.8/changes.html 14 Mar 2013 01:13:56 -0000 1.108
> +++ htdocs/gcc-4.8/changes.html 22 Mar 2013 10:22:37 -0000
> @@ -32,7 +32,12 @@ the number of iterations of loops using
> standards. This may cause non-conforming programs to no longer work as
> expected, such as SPEC CPU 2006 464.h264ref and 416.gamess. A new
> option, <code>-fno-aggressive-loop-optimizations</code>, was added
> -to disable this aggressive analysis.</p>
> +to disable this aggressive analysis. In some loops that have known
> +constant number of iterations, but undefined behavior is known to occur
> +in the loop before reaching or during the last iteration, GCC will warn
> +about the undefined behavior in the loop instead of deriving lower upper
> +bound of the number of iterations for the loop. The warning
> +can be disabled with <code>-Wno-aggressive-loop-optimizations</code>.</p>
>
> <p>On ARM, a bug has been fixed in GCC's implementation of the AAPCS
> rules for the layout of vectors that could lead to wrong code being
>
> Jakub
>
>
--
Richard Biener <rguenther@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend
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