On Wed, Nov 14, 2018 at 7:41 AM Richard Biener <richard.guent...@gmail.com> wrote: > > On Tue, Nov 13, 2018 at 10:25 PM Giuliano Augusto Faulin Belinassi > <giuliano.belina...@usp.br> wrote: > > > > Only do the optimization if flag_signed_zeros && > > !flag_finite_math_only is set, as suggested in the previous iteration. > > > > Before, the patch did the optimization even when -fno-signed-zeros and > > -ffinite-math-only was set. This could generate badly incorrect > > results for targets that do not support infinite or signed zeros. > > How's the result wrong if there are no signed zeros? Note that -ffast-math > enables -fno-signed-zeros for example. So both of your check look > backwards.
Indeed. After plotting the graph of both functions, it is very clear that this check isn't required. Sorry about that. > Also the support for signed zeros and infs/nans should be guarded with > > !HONOR_SIGNED_ZEROS (type) && !HONOR_NANS (type) && !HONOR_INFINITIES (type) > > which then means there's no difference between -0. and 0. and there are no > NaNs or Infs in the inputs and ouptut NaNs or Infs need not be produced. There can be NaNs and Infinities. For NaNs, take any input that is outside the [-1, 1] line. For Infinities, take x = -1, or x = 1. I think these must be 'honored' as to ensure compatibility with the original expression. so I must check for !HONOR_SIGNED_ZEROS (type) && HONOR_NANS (type) && HONOR_INFINITIES (type) that is correct? Also, is it safe to remove the !finite_math_only with this, as now it is stated that the type supports infinity and NaNs? However, I am not sure if it is OK to remove unsafe-math-optimizations even if it enables finite_math_only because of the 2 ULP error. As stated in the first iteration, the user can be using a very precise math library that yields 0 ULP. > Richard. > > > I also updated the tests with the proper flags. > > > > gcc/ChangeLog > > 2018-11-13 Giuliano Belinassi <giuliano.belina...@usp.br> > > > > * match.pd (sinh (atanh (x))): New simplification rules. > > (cosh (atanh (x))): Likewise. > > > > gcc/testsuite/ChangeLog > > 2018-11-13 Giuliano Belinassi <giuliano.belina...@usp.br> > > > > * gcc.dg/sinhatanh-1.c: New test. > > * gcc.dg/sinhatanh-2.c: New test. > > > > There are no tests in trunk that seems to be breaking because of this patch.
