https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63411
amker at gcc dot gnu.org changed:
What |Removed |Added
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CC| |amker at gcc dot gnu.org
--- Comment #4 from amker at gcc dot gnu.org ---
(In reply to Oleg Endo from comment #3)
> (In reply to bin.cheng from comment #2)
> > > bt/s .L3
> > > mov r1,r2
> > > add #3,r2 <<< wrong struct offset '3'
> > But r2 is initialized with [.L14] which is _OAM3+3, so the offset actually
> > is 6 here, No?
>
> Ouch. Yes. Sorry for the fuzz.
> On SH this is a performance regression (it can do only displacements that
> are scaled by the access size), but not a wrong-code regression.
We saw similar problems on arm too. Problem is IVOPT's model doesn't know the
detail of target addressing mode. This is should be fixed by improving
function get_address_cost, but that's just difficult to expose every target
details to middle end, especially we need to keep it simple and fast.
