Re: ping Zdenek's patch for 17428

[Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>]

Hello,

> > Zdenek has a patch:
> > http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02116.html
> >
> > which fixes 17428 and 17491.  It looks very safe, but has apparently
> > not been reviewed.
> 
> The change to value-prof.c is obviously acceptable, but my feeling
> is that the change to safe_insert_insn_on_edge is probably far to
> big a hammer.  To work around the reload failure of a prefetch insn,
> do we really need to spill and restore every hard register that's
> live over that edge.  On PowerPC, this spills any altivec registers
> in use, on x86, this spills any x87, MMX and SSE registers, etc...

I believe that most of the time no hard register at all should be live
at the point where the insertion happens.  This is the reason why I did
not want to make things more complicated than necessary.  Simply
disabling the optimization in case any hard reg is live at the point
would IMHO work as well.

Zdenek