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[Bug rtl-optimization/13931] [3.4/4.0/4.1 Regression] combiner much slower on big basic blocks
- From: "ian at airs dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 8 Oct 2005 05:04:36 -0000
- Subject: [Bug rtl-optimization/13931] [3.4/4.0/4.1 Regression] combiner much slower on big basic blocks
- References: <bug-13931-7849@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #33 from ian at airs dot com 2005-10-08 05:04 -------
I found the bug report which led to the patch which is the issue in this PR.
It starts here:
http://gcc.gnu.org/ml/gcc-patches/2003-05/msg00796.html
and ends with this patch:
http://gcc.gnu.org/ml/gcc-patches/2003-05/msg01358.html
I will try to recreate this problem. It looks like we should be able to fix
this specific type of problem without losing any speed. We should just should
not skip adding the REG_DEAD note if we don't directly set the register. It
actually looks like the code works that way anyhow, but with luck I will be
able to recreate the problem and figure out what is really happening.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13931