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Re: [Bug middle-end/43861] 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So is this actually a bug or is the documentation outdated or even both?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




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