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Re: Reload Issue -- I can't believe we haven't hit this before

On Tue, 2005-04-19 at 21:36 +0200, Eric Botcazou wrote:
> > > For 3.3 and 3.4, this was "fixed" by not recording memory equivalences
> > > that have the infamous RTX_UNCHANGING_P flag set.
> >
> > Also a possibility.  Making the equivalent change (!MEM_READONLY_P)
> > appears to do the trick for mainline.
> 
> Yes, but that's of course not optimal, unnecessary spills are generated.
True.  That's one of the reasons why I mentioned the possibility
of finding these insns and simply removing them.

Think about it for a while -- given a SET where the SET_SRC is a 
pseudo which did not get a hard register and is equivalenced to
a read-only memory location, then the SET must be dead as it
can only be setting the memory location to the value already
in the memory location.

jeff
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