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Re: Fix PR 46297
- From: Richard Guenther <richard dot guenther at gmail dot com>
- To: Jeff Law <law at redhat dot com>
- Cc: gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Sat, 6 Nov 2010 21:20:19 +0100
- Subject: Re: Fix PR 46297
- References: <4CD579EE.firstname.lastname@example.org>
On Sat, Nov 6, 2010 at 4:53 PM, Jeff Law <email@example.com> wrote:
> ?The fundamental problem is some ports have embedded auto-inc addressing
> modes without REG_INC nodes. ?The improved reload optimizations were not
> accounting for the possibility of embedded auto-inc addressing, particularly
> for argument pushing.
> As a result the new optimization applied, but the offset we generated in the
> MEM was wrong due to the intervening autoinc addressing mode.
> While we could track the auto-incs, it's far easier to treat them as an
> unrecordable use/set which disables the optimization across the argument
> pushes. ? While we lose a few optimization opportunities, I suspect they
> definitely fall into the unmeasurable category.
> Bootstrapped & regression tested on i686-pc-linux-gnu.
Can we detect this in RTL checking and fixup the targets? Obviously not
for stage3 though.