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Re: Line insn notes in modulo-sched
- From: Ayal Zaks <ZAKS at il dot ibm dot com>
- To: Steven Bosscher <stevenb dot gcc at gmail dot com>
- Cc: gcc at gcc dot gnu dot org, Jan Hubicka <jh at suse dot cz>
- Date: Tue, 14 Mar 2006 13:10:55 +0200
- Subject: Re: Line insn notes in modulo-sched
Steven Bosscher <email@example.com> wrote on 14/03/2006 01:32:09:
> Hi Ayal,
> The SMS implementation in GCC, in modulo-sched.c, uses line notes
> to find insn locations, see find_line_note. Why are you using
> line notes instead of insn locators? Line notes are on the list
> of Things That Should Not Be, and insn locators replace them. Is
> there a reason for modulo-sched to rely on loop notes, or is this
> just an oversight?
The idea was to reorder/duplicate each insn together with its line note (or
rather, reorder/duplicate an interval of insns starting from
node->first_note until the node->insn itself). Compared to haifa-sched's
scheme of saving the notes, reordering the insns, then restoring the notes.
The line notes are not used to find insn locations -- we carry them along
because we had to. If we no longer need to worry about keeping each line
note adjacent to its insn during scheduling, that would simplify things.
Line notes are also used to dump SMS statistics, but for that any locator
Not sure about "loop notes"?