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Re: decrement and branch optimization broken?
- To: gcc at gcc dot gnu dot org, zippel at linux-m68k dot org
- Subject: Re: decrement and branch optimization broken?
- From: Jan Hubicka <jh at suse dot cz>
- Date: Fri, 27 Jul 2001 17:05:59 +0200
Hi,
gcc now does have new dbra code in loop.c. You may see i386 loop instruction
about how to generate them correctly (note that using loop instruction on i386
in gcc3.0 causes bootstrap failure, so there may be bug lurking around - I would
suggest you first stabilize bootstrap and then try this).
I still think combine should be able to produce the instruction in the
sequence you point out.
I would suggest you to add debug_rtx (pat) to recog_for_combine and see if it
does not construct slightly different pattern. If not write minimal example,
break point try_combine and try to figure out where combine gets to wrong
track.
Honza