[Bug rtl-optimization/27437] [4.2 Regression]: -O3 regression due to SEE

[hjl at lucon dot org]

------- Comment #7 from hjl at lucon dot org  2006-05-05 15:49 -------
(In reply to comment #6)
> (In reply to comment #5)
> > There are several problems with the current SEE implementation:
> > 
> > 1. SEE uses NEXT_INSN/PREV_INSN to find adjacent insns to check if SEE
> > is safe. But with -g, NEXT_INSN/PREV_INSN may point to a NOTE:
> > 
> 
> That one is easy to fix.  Please post a patch to using
> next_nonnote_insn/prev_nonnote_insn instead.
> 
> And then the -O3 (without -g) is a different issue.
> 


You are right. Using next_nonnote_insn/prev_nonnote_insn won't solve  -O3
(without -g). One real problem is SEE can't determine if SEE is safe by just
looking at next_nonnote_insn/prev_nonnote_insn. The relevant insn may be a few
more insns away. Denis, do you have a patch to address this?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27437