[Bug middle-end/29256] [4.2/4.3 regression] loop performance regression

[rakdver at kam dot mff dot cuni dot cz]

------- Comment #21 from rakdver at kam dot mff dot cuni dot cz  2008-01-11 04:44 -------
Subject: Re:  [4.2/4.3 regression] loop performance regression

> Is the testcase gcc.dg/tree-ssa/loop-19.c supposed to work with -fpic/-fPIC?

not necessarily; with -fpic, both memory accesses are fully
strength-reduced, which seems to be the correct thing to do; however,

> I'm getting failures on mainline and 4.2 with x86_64, and only on 4.2 with
> i686.  Mainline i686 seems to work though.

the difference in the costs of the two variants is so small that you
will basically get one of them at random.  This test is not intended to
be run with -fpic.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29256