[Bug tree-optimization/36439] [4.3 Regression] very long compile-time in PRE building gimp-plugin-registry
------- Comment #14 from rguenther at suse dot de 2010-03-19 10:09 -------
Subject: Re: [4.3 Regression] very long
compile-time in PRE building gimp-plugin-registry
On Fri, 19 Mar 2010, kurt at garloff dot de wrote:
> ------- Comment #11 from kurt at garloff dot de 2010-03-19 00:34 -------
> (In reply to comment #10)
> > GCC 4.3.4 is being released, adjusting target milestone.
>
> Very non-scientific benchmark:
> Did compile latest gmic-1.3.4.0 on a 2xL5540 system (plenty of RAM) with make
> -j8 and compile flags:
> -O3 --param max-inline-insns-auto=200 -ffast-math -funroll-loops
> -ftree-vectorize
> Times (in seconds, user, elapsed):
> 4.3.5: 1263u, 377e
> w/ -fno-tree-pre: 755u, 202e
> 4.4.4: 1022u, 311e
> w/ -fno-tree-pre: 996u, 284e
> 4.5.0: 2325u, 615e
> w/ -fno-tree-pre: 1974u, 543e
>
> Note that this is in contrast to earlier observations that 4.4/4.5 did do much
> better than 4.3. Don't know whether that's caused by changed gmic code or
> whether we have regressed in 4.5. Let me know if you want me to pick one file
> that takes particularly long to compile and investigate further.
This bug was about PRE causing compile-time issues at -O2 which is
what was investigated and fixed for the testcases attached to this PR.
I see, for -O2 and the CImg.C testcase (just using openSUSE packages
from devel:gcc):
4.3.4 (r152973): stopped after 4min
4.4.2 (r155966): 68s
4.5.0 (r157384): 74s
also see PR43415 for a similar problem where I am about to commit a
patch.
If you can provide a testcase for plain -O3 [-ffast-math -funroll-loops]
being slow it would be appropriate to open a new bugreport for it.
Thanks,
Richard.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36439
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