On Fri, Apr 28, 2017 at 10:23 PM, Marc Glisse <marc.gli...@inria.fr> wrote: > On Fri, 28 Apr 2017, Richard Biener wrote: > >> On Fri, Apr 28, 2017 at 1:35 PM, Marc Glisse <marc.gli...@inria.fr> wrote: >>> >>> Hello, >>> >>> surprisingly, this did not cause any Wstrict-overflow failure. Some of it >>> sounds more like reassoc's job, but it is convenient to handle simple >>> cases >>> in match.pd. I think we could wait until there are reports of regressions >>> related to register pressure before adding single_use tests. >>> >>> For a std::vector<long> v, we now simplify v.size()==v.capacity() to a >>> single comparison (long)finish==(long)end_storage (I guess I could still >>> try >>> to drop the casts to consider it really done). Handling >>> v.size()<v.capacity() seems much harder, because of C++'s questionable >>> choice to use unsigned types. I may still be able to remove the >>> divisions, >>> I'll see if I can sprinkle some 'convert' in recent transformations. >>> >>> Bootstrap+regtest on powerpc64le-unknown-linux-gnu. >> >> >> +(for cmp (eq ne minus) >> >> Fat fingered 'minus' (in all places) or did you want to get fancy? >> (the transforms >> look valid even for cmp == minus) Maybe adjust comments to reflect this. > > > I started with just comparisons and then noticed that minus worked as well. > I'll adjust the comment and rename cmp to op as suggested by Jakub. I may > have to separate the minus case when I add converts in a future patch. > >> There are a few related cases in fold-const.c, namely X +- Y CMP X -> Y >> CMP 0, >> some of them also handling POINTER_PLUS_EXPR. So I wonder if you can >> handle pointer_plus like plus and maybe move those fold-const.c patterns. > > > You already added (T)(P + A) - (T)(P + B) -> (T)A - (T)B, so I'll have to > take care to avoid redundancy. Since it was meant for pointer_plus more than > plus, you used convert, not convert?, and it is currently not redundant with > my patch. If I integrate pointer_plus in the same transformation, I will > probably have to use :C instead of :c, and we will get 2 dead paths > (operand_equal_p on the first argument of one pointer_plus and the second > argument of another pointer_plus), it might be easier as a separate pattern.
Yes. Just spotted the few patterns in fold-const.c when searching for things doing the transform you add. Richard. > -- > Marc Glisse
