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Re: RTL alias analysis
- From: Mark Mitchell <mark at codesourcery dot com>
- To: Steven Bosscher <steven dot bosscher at gmail dot com>
- Cc: Richard Henderson <rth at redhat dot com>, Jan Hubicka <jh at suse dot cz>, gcc at gcc dot gnu dot org
- Date: Sun, 01 Jan 2006 10:22:56 -0800
- Subject: Re: RTL alias analysis
- References: <200512292242.17272.stevenb@suse.de> <200512292353.31258.stevenb@suse.de> <20051229225838.GE11833@kam.mff.cuni.cz> <200512300015.09257.stevenb@suse.de> <200601011821.49043.steven@gcc.gnu.org>
Steven Bosscher wrote:
> Hi rth,
>
> The stack space sharing you added to cfgexpand.c breaks RTL alias
> analysis.
>
> For example, the attached test case breaks for pentiumpro at -O2.
> The problem apparently is that the second store to c is moved up
> before before the load.
My guess at a solution is that when A (with alias set S_a) and B (with
alias set S_b) are given the same stack slot, we should create a new
alias set S_c which is a subset of both S_a and S_b, and give the
combined stack slot that aliase set.
--
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com
(650) 331-3385 x713