https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93806
--- Comment #47 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by hongtao Liu <liuho...@gcc.gnu.org>: https://gcc.gnu.org/g:77a50c772771f681085922b493922516c3c03e9a commit r14-2085-g77a50c772771f681085922b493922516c3c03e9a Author: liuhongt <hongtao....@intel.com> Date: Sun Jun 25 11:35:09 2023 +0800 Don't use intermiediate type for FIX_TRUNC_EXPR when ftrapping-math. > > Hmm, good question. GENERIC has a direct truncation to unsigned char > > for example, the C standard generally says if the integral part cannot > > be represented then the behavior is undefined. So I think we should be > > safe here (0x1.0p32 doesn't fit an int). > > We should be following Annex F (unspecified value plus "invalid" exception > for out-of-range floating-to-integer conversions rather than undefined > behavior). But we don't achieve that very well at present (see bug 93806 > comments 27-29 for examples of how such conversions produce wobbly > values). That would mean guarding this with !flag_trapping_math would be the appropriate thing to do. gcc/ChangeLog: PR tree-optimization/110371 PR tree-optimization/110018 * tree-vect-stmts.cc (vectorizable_conversion): Don't use intermiediate type for FIX_TRUNC_EXPR when ftrapping-math. gcc/testsuite/ChangeLog: * gcc.target/i386/pr110018-1.c: Add -fno-trapping-math to dg-options. * gcc.target/i386/pr110018-2.c: Ditto.
