On 8/16/19 2:09 PM, Jan Hubicka wrote: >> On Thu, Aug 15, 2019 at 4:17 PM Jan Hubicka <hubi...@ucw.cz> wrote: >>> >>>> On Tue, Aug 6, 2019 at 5:44 PM Martin Liska <mli...@suse.cz> wrote: >>>>> >>>>> >>>>> gcc/ChangeLog: >>>> >>>> So I suppose this isn't to call operand_equal_p on two FIELD_DECLs >>>> but to make two COMPONENT_REFs "more equal"? If so I then >>> >>> yes. The patch originates from my original patchset I believe and it is >>> what ICF does. >>>> I suggest to make this change "local" to the COMPONENT_REF handling. >>>> This also interacts with path-based disambiguation so you want to make >>>> sure to only make things equal here iff it wouldn't change the outcome >>>> of path-based analysis. Honza? >>> >>> Indeed this can be handled as part of COMPONENT_REF match. >>> Access path oracle here basically checks: >>> 1) that MEM_REF type matches (we want predicate for this) >>> 2) if it finds type match via same_type_for_tbaa and then it applies >>> the assumption about disjointness or overlap >>> >>> So I guess ideally we should >>> >>> 1) do matching part of COMPONENT_REF >>> 2) compare OFFSET, BIT_OFFSET >>> This establishes that the access has same semantics. >>> 3) for -fno-strict-aliasing be happy >>> 4) for -fstrict-aliaisng check if access path applies (we should export >>> predicate from tree-ssa-alias as discussed earlier) >>> 5) compare types by same_type_for_tbaa_p >> >> Ick. This smells like a layering violation to me. IMHO this extended >> equality handling should be handled with the overloading/callback >> and not in native operand_equal_p. Either on the level of the >> COMPONENT_REF itself (sounds like that would be needed) >> or the FIELD_DECL. Not sure if the above suggestions make >> it neccessary to look at more than a single COMPONENT_REF/FIELD_DECL >> in the access path. If so then watch out for quadraticness as >> operand_equal_p >> traverses a reference chain... > > I suppose we want to match whole access paths at once, since only having > the MEM_REF allows one to check whether access path oracle applies to > the given reference or not...
Doing that, can you please Honza point me to a function that should be used for it? Martin > > Honza >> >> Richard. >> >>> Honza
