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Re: very confused about single_set
- From: Daniel Berlin <dberlin at dberlin dot org>
- To: Kenneth Zadeck <zadeck at naturalbridge dot com>
- Cc: Steven Bosscher <stevenb dot gcc at gmail dot com>, Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>, GCC <gcc at gcc dot gnu dot org>
- Date: Sun, 19 Feb 2006 10:22:55 -0500
- Subject: Re: very confused about single_set
- References: <43F88717.4090806@naturalbridge.com>
On Sun, 2006-02-19 at 09:56 -0500, Kenneth Zadeck wrote:
> Steven, Zdenek
>
> 1) single_set is built on top of single_set2.
Yes
> 2) single_set_2 uses REG_UNUSED notes.
Only if there are multiple sets.
> 3) tree-ssa-loop-ivops.c:seq_cost uses single_set.
This is because Zdenek builds RTL to determine target costs.
>
> I can find no indication that rtl dfa is run here to provide the
> information for single_set to produce the correct answer.
I don't understand what you mean.
Why does the DFA need to be run to produce the correct answer?
(Our ports use Deterministic Finite Automaton based schedulers, so
saying DFA is an ambiguous term at best)
Or do you mean DataFlow Analysis, in which case, i'm sure everyone
expects the notes are always up to date (even though they may not be).