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Re: Patch to rtx_varies_p to improve pic code on PA
- To: dave at hiauly1 dot hia dot nrc dot ca (John David Anglin)
- Subject: Re: Patch to rtx_varies_p to improve pic code on PA
- From: "John David Anglin" <dave at hiauly1 dot hia dot nrc dot ca>
- Date: Sat, 17 Mar 2001 00:50:03 -0500 (EST)
- Cc: gcc-patches at gcc dot gnu dot org
> 2001-03-09 John David Anglin <dave@hiauly1.hia.nrc.ca>
>
> * explow.c (stabilize): Call rtx_varies_p instead of rtx_unstable_p.
> * regmove.c (stable_and_no_regs_but_for_p): Likewise.
> * rtlanal.c (rtx_varies_p): Treat an unchanging register operand as
> constant for alias analysis. Treat the pic offset table register as
> constant even when PIC_OFFSET_TABLE_REG_CALL_CLOBBERED is defined.
> Update comments.
In looking at test results with and without this patch, I see that that the
patch does in fact eliminate at least one failing test case under i686
linux. For example, compare these results:
<http://gcc.gnu.org/ml/gcc-testresults/2001-03/msg00243.html>
and
<http://gcc.gnu.org/ml/gcc-testresults/2001-03/msg00245.html>.
I don't see any failures of 20001226-1.c with the patch installed.
Dave
--
J. David Anglin dave.anglin@nrc.ca
National Research Council of Canada (613) 990-0752 (FAX: 952-6605)