[Bug tree-optimization/30052] [4.2 Regression] points-to analysis slow and memory hungry

["rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>]

------- Comment #61 from rguenther at suse dot de  2008-06-11 08:07 -------
Subject: Re:  [4.2 Regression] points-to analysis
 slow and memory hungry

On Tue, 10 Jun 2008, giovannibajo at libero dot it wrote:

> ------- Comment #60 from giovannibajo at libero dot it  2008-06-10 17:26 -------
> If a knowledgable GCC developer could suggest *any* workaround at -O1 for this
> bug in 4.2 (including disabling whatever alias analysys causes the problem), it
> might be proposed as a fix within distros at least.

You can try if --param max-fields-for-field-sensitive=0 improves the
situation.

Other than that, try, in 
tree-ssa-structalias.c:create_variable_info_for remove the
make_constraint_from_escaped and make_constraint_to_escaped calls for
the is_global cases.  Note that you need to adjust find_what_p_points_to
to include escaped variables if escaped_id is set in the solution and
that call clobbering will need similar adjustments (and remember
escaped_id includes all globals implicitly).  The problem with the
sipQt testcase is that it has 10000s of global vars it creates
constraints for, even though they are unused.

Richard. 


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30052