https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109008
--- Comment #49 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:44f80a370b76fd1564e280f08d6640d0f641d487 commit r13-6580-g44f80a370b76fd1564e280f08d6640d0f641d487 Author: Jakub Jelinek <ja...@redhat.com> Date: Fri Mar 10 12:40:23 2023 +0100 range-op-float: Extend lhs by 0.5ulp rather than 1ulp if not -frounding-math [PR109008] This patch, incremental to the just posted one, improves the reverse operation ranges significantly by widening just by 0.5ulp in each direction rather than 1ulp. Again, REAL_VALUE_TYPE has both wider exponent range and wider mantissa precision (160 bits) than any supported type, this patch uses the latter property. The patch doesn't do it if -frounding-math, because then the rounding can be +-1ulp in each direction depending on the rounding mode which we don't know, or for IBM double double because that type is just weird and we can't trust in sane properties. I've performed testing of these 2 patches on 300000 random tests as with yesterday's patch, exact numbers are in the PR, but I see very significant improvement in the precision of the ranges while keeping it conservatively correct. 2023-03-10 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/109008 * range-op-float.cc (float_widen_lhs_range): If not -frounding-math and not IBM double double format, extend lhs range just by 0.5ulp rather than 1ulp in each direction.
