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[Bug middle-end/23488] [4.1/4.2 Regression] GCSE load PRE does not work with non sets
- From: "dann at godzilla dot ics dot uci dot edu" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 3 Mar 2006 02:14:32 -0000
- Subject: [Bug middle-end/23488] [4.1/4.2 Regression] GCSE load PRE does not work with non sets
- References: <bug-23488-1008@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #18 from dann at godzilla dot ics dot uci dot edu 2006-03-03 02:14 -------
(In reply to comment #17)
> (In reply to comment #5)
> > It's strange that the load(*) does not get optimized, given that it's in the
> > same BB as the store that precedes it...
> >
> > movl %eax, result.1282
> > (*) movl result.1282, %eax
>
> This is because the copying of the trace is happening at the very end of the
> optimization phase so it does not optimized at all.
Right, the copying happens in .bbro (as shown in PR26537).
gcc-4.0 did the same kind of copying in .bbro, but it did not generate the
redundant mov.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23488