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* [Bug middle-end/43861] New: -Os creates larger binaries than before in some cases (-falign-... options enabled)
@ 2010-04-22 23:48 rwahl at gmx dot de
2010-04-22 23:51 ` [Bug middle-end/43861] " pinskia at gmail dot com
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: rwahl at gmx dot de @ 2010-04-22 23:48 UTC (permalink / raw)
To: gcc-bugs
Hi,
I just noticed that some of my libraries are greater when compiled with gcc
4.4.3 instead of gcc 4.3.2. Diffing the output of "gcc --help=optimizers -Q
-Os" shows this in 4.3.2:
-falign-jumps [disabled]
-falign-labels [disabled]
-falign-loops [enabled]
and this for 4.4.3:
-falign-functions [enabled]
-falign-jumps [enabled]
-falign-labels [enabled]
-falign-loops [disabled]
when explicitely disabling the alignment options then the code size shrinks.
For libxml2 in my case from 704256 to 675584 bytes.
The manual says:
-Os disables the following optimization flags: -falign-functions
-falign-jumps -falign-loops -falign-labels -freorder-blocks
-freorder-blocks-and-partition -fprefetch-loop-arrays
-ftree-vect-loop-version
which is not true (even not for 4.3.2 since loop alignment was enabled). Some
other opts like -freorder-blocks is enabled as well.
So is this actually a bug or is the documentation outdated or even both?
--
Summary: -Os creates larger binaries than before in some cases (-
falign-... options enabled)
Product: gcc
Version: 4.4.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rwahl at gmx dot de
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43861
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Bug middle-end/43861] New: -Os creates larger binaries than before in some cases (-falign-... options enabled)
2010-04-22 23:48 [Bug middle-end/43861] New: -Os creates larger binaries than before in some cases (-falign-... options enabled) rwahl at gmx dot de
2010-04-22 23:51 ` [Bug middle-end/43861] " pinskia at gmail dot com
@ 2010-04-22 23:51 ` Andrew Pinski
2010-04-23 0:10 ` [Bug middle-end/43861] " rwahl at gmx dot de
2010-05-02 16:55 ` rwahl at gmx dot de
3 siblings, 0 replies; 5+ messages in thread
From: Andrew Pinski @ 2010-04-22 23:51 UTC (permalink / raw)
To: gcc-bugzilla; +Cc: gcc-bugs
Which target is this for?
Sent from my iPhone
On Apr 22, 2010, at 4:48 PM, "rwahl at gmx dot de" <gcc-bugzilla@gcc.gnu.org
> wrote:
> Hi,
>
> I just noticed that some of my libraries are greater when compiled
> with gcc
> 4.4.3 instead of gcc 4.3.2. Diffing the output of "gcc --
> help=optimizers -Q
> -Os" shows this in 4.3.2:
>
> -falign-jumps [disabled]
> -falign-labels [disabled]
> -falign-loops [enabled]
>
> and this for 4.4.3:
>
> -falign-functions [enabled]
> -falign-jumps [enabled]
> -falign-labels [enabled]
> -falign-loops [disabled]
>
> when explicitely disabling the alignment options then the code size
> shrinks.
> For libxml2 in my case from 704256 to 675584 bytes.
>
> The manual says:
>
> -Os disables the following optimization flags: -falign-functions
> -falign-jumps -falign-loops -falign-labels -freorder-
> blocks
> -freorder-blocks-and-partition -fprefetch-loop-arrays
> -ftree-vect-loop-version
>
> which is not true (even not for 4.3.2 since loop alignment was
> enabled). Some
> other opts like -freorder-blocks is enabled as well.
>
> So is this actually a bug or is the documentation outdated or even
> both?
>
>
> --
> Summary: -Os creates larger binaries than before in some
> cases (-
> falign-... options enabled)
> Product: gcc
> Version: 4.4.3
> Status: UNCONFIRMED
> Severity: normal
> Priority: P3
> Component: middle-end
> AssignedTo: unassigned at gcc dot gnu dot org
> ReportedBy: rwahl at gmx dot de
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43861
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/43861] -Os creates larger binaries than before in some cases (-falign-... options enabled)
2010-04-22 23:48 [Bug middle-end/43861] New: -Os creates larger binaries than before in some cases (-falign-... options enabled) rwahl at gmx dot de
@ 2010-04-22 23:51 ` pinskia at gmail dot com
2010-04-22 23:51 ` [Bug middle-end/43861] New: " Andrew Pinski
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gmail dot com @ 2010-04-22 23:51 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from pinskia at gmail dot com 2010-04-22 23:51 -------
Subject: Re: New: -Os creates larger binaries than before in some cases
(-falign-... options enabled)
Which target is this for?
Sent from my iPhone
On Apr 22, 2010, at 4:48 PM, "rwahl at gmx dot de" <gcc-bugzilla@gcc.gnu.org
> wrote:
> Hi,
>
> I just noticed that some of my libraries are greater when compiled
> with gcc
> 4.4.3 instead of gcc 4.3.2. Diffing the output of "gcc --
> help=optimizers -Q
> -Os" shows this in 4.3.2:
>
> -falign-jumps [disabled]
> -falign-labels [disabled]
> -falign-loops [enabled]
>
> and this for 4.4.3:
>
> -falign-functions [enabled]
> -falign-jumps [enabled]
> -falign-labels [enabled]
> -falign-loops [disabled]
>
> when explicitely disabling the alignment options then the code size
> shrinks.
> For libxml2 in my case from 704256 to 675584 bytes.
>
> The manual says:
>
> -Os disables the following optimization flags: -falign-functions
> -falign-jumps -falign-loops -falign-labels -freorder-
> blocks
> -freorder-blocks-and-partition -fprefetch-loop-arrays
> -ftree-vect-loop-version
>
> which is not true (even not for 4.3.2 since loop alignment was
> enabled). Some
> other opts like -freorder-blocks is enabled as well.
>
> So is this actually a bug or is the documentation outdated or even
> both?
>
>
> --
> Summary: -Os creates larger binaries than before in some
> cases (-
> falign-... options enabled)
> Product: gcc
> Version: 4.4.3
> Status: UNCONFIRMED
> Severity: normal
> Priority: P3
> Component: middle-end
> AssignedTo: unassigned at gcc dot gnu dot org
> ReportedBy: rwahl at gmx dot de
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43861
>
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43861
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/43861] -Os creates larger binaries than before in some cases (-falign-... options enabled)
2010-04-22 23:48 [Bug middle-end/43861] New: -Os creates larger binaries than before in some cases (-falign-... options enabled) rwahl at gmx dot de
2010-04-22 23:51 ` [Bug middle-end/43861] " pinskia at gmail dot com
2010-04-22 23:51 ` [Bug middle-end/43861] New: " Andrew Pinski
@ 2010-04-23 0:10 ` rwahl at gmx dot de
2010-05-02 16:55 ` rwahl at gmx dot de
3 siblings, 0 replies; 5+ messages in thread
From: rwahl at gmx dot de @ 2010-04-23 0:10 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from rwahl at gmx dot de 2010-04-23 00:10 -------
All my own cross compilers for ARM and x86 hosted on x86 and the native gcc in
Fedora 12 (x86) show this behavior.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43861
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/43861] -Os creates larger binaries than before in some cases (-falign-... options enabled)
2010-04-22 23:48 [Bug middle-end/43861] New: -Os creates larger binaries than before in some cases (-falign-... options enabled) rwahl at gmx dot de
` (2 preceding siblings ...)
2010-04-23 0:10 ` [Bug middle-end/43861] " rwahl at gmx dot de
@ 2010-05-02 16:55 ` rwahl at gmx dot de
3 siblings, 0 replies; 5+ messages in thread
From: rwahl at gmx dot de @ 2010-05-02 16:55 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from rwahl at gmx dot de 2010-05-02 16:55 -------
Created an attachment (id=20535)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20535&action=view)
Disable alignment when using -Os
The attached patch fixes the problem. It could be written in a more elegant way
by changing just opt1_max but this would modify the semantic of this variable
and it should be renamed accordingly.
On ARM the fix is probably a NOP because the default alignment seems to be 1
anyway but I haven't checked this.
The output of "gcc -Q --help=optimizers" seems to be broken for the alignment
options because on one hand these options are not boolean and on the other hand
falign-loops is reported as enabled when it has been disabled and vice versa.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43861
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2010-05-02 16:55 UTC | newest]
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2010-04-22 23:48 [Bug middle-end/43861] New: -Os creates larger binaries than before in some cases (-falign-... options enabled) rwahl at gmx dot de
2010-04-22 23:51 ` [Bug middle-end/43861] " pinskia at gmail dot com
2010-04-22 23:51 ` [Bug middle-end/43861] New: " Andrew Pinski
2010-04-23 0:10 ` [Bug middle-end/43861] " rwahl at gmx dot de
2010-05-02 16:55 ` rwahl at gmx dot de
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