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Re: [PATCH][2/n] alias.c TLC
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Richard Guenther <rguenther at suse dot de>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 15 Jun 2012 11:08:29 -0700
- Subject: Re: [PATCH][2/n] alias.c TLC
- References: <Pine.LNX.4.64.1206111629390.29541@jbgna.fhfr.qr>
On Mon, Jun 11, 2012 at 7:32 AM, Richard Guenther <rguenther@suse.de> wrote:
>
> This makes ao_ref_from_mem less conservative if either MEM_OFFSET or
> MEM_SIZE is not set. ?From other alias.c code and
> set_mem_attributes_minus_bitpos one has to conclude that MEM_EXPR
> is always conservatively correct (it only can cover a larger memory
> area) and the MEM_OFFSET / MEM_SIZE pair can refine it. ?Thus,
> we can make ao_ref_from_mem less conservative when, for example,
> faced with variable array accesses which set_mem_attributes_minus_bitpos
> ends up representing with an unknown MEM_OFFSET.
>
> Bootstrap and regtest running on x86_64-unknown-linux-gnu.
>
> Richard.
>
> 2012-06-11 ?Richard Guenther ?<rguenther@suse.de>
>
> ? ? ? ?* emit-rtl.c (set_mem_attributes_minus_bitpos): Remove dead code.
> ? ? ? ?* alias.c (ao_ref_from_mem): MEM_EXPR is conservative, MEM_OFFSET
> ? ? ? ?and MEM_SIZE only refines it. ?Reflect that and be less conservative
> ? ? ? ?if either of the latter is not known.
>
This caused:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53688
--
H.J.