On 4/29/19 9:58 PM, Prathamesh Kulkarni wrote: > On Tue, 30 Apr 2019 at 02:56, Jeff Law <l...@redhat.com> wrote: >> >> On 1/30/19 7:10 AM, Bárbara de Castro Fernandes wrote: >>> This patch simplifies the function tanh (x) * cosh (x) -> sinh (x). >>> This rule is derived from the relationship between hyperbolic >>> functions. >>> >>> I ran the tests and gfortran.dg/pr79966.f90 failed, but this failure >>> is unrelated to the patch (see >>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88711 for more >>> information). My architecture is x86_64. >>> >>> gcc/ChangeLog: >>> 2019-01-30 Bárbara Fernandes <barbara.fernan...@usp.br> >>> >>> * match.pd (tanh (x) * cosh (x)): New simplification rule. >>> >>> gcc/testsuite/ChangeLog: >>> 2019-01-30 Bárbara Fernandes <barbara.fernan...@usp.br> >>> >>> * tanhtimescosh.c: New test. >> So how does this behave for numbers extremely close to zero in practice >> and do we have to worry about overflow problems when cosh(x) gets large? > Hi Jeff, > Just curious, do we want to add math identities like above to match.pd ? I'd think so.
> In practice, I am not sure how often we'd see "tanh * cosh" instead > of sinh directly in source, We're often surprised when what ultimately shows up in sources :-) And a transformation that allows us to turn two transcendentals and a multiplication into a single transcendental is going to be a big win. > altho it seems we do simplify tan * cos -> sin. > In general, I suppose there are lot of identities we haven't added > because the likelihood of "match" part isn't high. Perhaps. I have to assume the submitter submitted this particular simplification for a reason. jeff
