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Re: Remove all CSE skip blocks code
- From: Roger Sayle <roger at eyesopen dot com>
- To: Steven Bosscher <stevenb dot gcc at gmail dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 21 Nov 2006 16:14:51 -0700 (MST)
- Subject: Re: Remove all CSE skip blocks code
On Tue, 21 Nov 2006, Steven Bosscher wrote:
> * cse.c (enum taken): Remove PATH_AROUND.
> (addr_affects_sp_p, invalidate_skipped_set,
> invalidate_skipped_block): Remove.
> (cse_end_of_basic_block): Remove skip_blocks and related code.
> (cse_main): Don't test for flag_cse_skip_blocks.
> Update cse_end_of_basic_block call.
> (cse_basic_block): Likewise. Remove PATH_AROUND case. Remove
> code to lengthen the path if a jump was simplified.
This is OK for mainline, thanks. I think we can defer a decision on
the -fcse-skip-blocks for a little while, until we see how things
progress with the CSE rewrite. We might end up with a "pseudos live
at start" implementation that provides functionality equivalent to
path following. In which case, it might make sense to retain the
historical option names. Alternatively, future stage 1 changes may
deprecate other CSE/GCSE command line options, and it may make sense
to decide upon their fate at the same time. As long as we have a
consistent strategy (and documentation) going into stage 2, I'm happy
to let things diverge temporarily in the meantime.
I'm not sure I agree with Richard's proposal of deprecating this command
line option for 4.2, where this option still does something useful. Even
if it will go away. I think we'll probably keep it as a no-op with a
deprecated warning for 4.3, and then remove it for 4.4 (as with Zdenek's