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Re: "REG_FREQ (i) = 0;" needed for 3.3 branch?
- From: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
- To: Kazu Hirata <kazu at cs dot umass dot edu>
- Cc: jh at suse dot cz, gcc at gcc dot gnu dot org
- Date: Sat, 6 Sep 2003 13:23:02 +0200
- Subject: Re: "REG_FREQ (i) = 0;" needed for 3.3 branch?
- References: <20030902.210841.11604387.kazu@cs.umass.edu>
Hello,
> Do you think we need to backport to 3.3 branch the following patch,
> which zeros REG_FREQ (i)?
>
> http://gcc.gnu.org/ml/gcc/2002-12/msg01237.html
>
> 2002-12-20 Zdenek Dvorak <rakdver@atrey.karlin.mff.cuni.cz>
>
> * flow.c (allocate_reg_life_data): Reset REG_FREQ.
>
> The reason for asking you about this is that I just found out that PR
> 11576, which occurs only on 3.3 branch, could be fixed with your
> patch. (Actually, PR 11576 was applicable to mainline up until you
> installed the patch.)
the patch should not spoil anything; on the other hand it almost
certainly does not fix the real cause of the bug. The patch causes
that preferences somewhere in register allocator are a bit different
(more sane); but the produced code should be correct irrespectively of
this. Therefore I believe the patch just masks some bug in register
allocation/reload.
Zdenek