https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112600
--- Comment #13 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Uros Bizjak <u...@gcc.gnu.org>: https://gcc.gnu.org/g:de05e44b2ad9638d04173393b1eae3c38b2c3864 commit r15-1113-gde05e44b2ad9638d04173393b1eae3c38b2c3864 Author: Uros Bizjak <ubiz...@gmail.com> Date: Sat Jun 8 12:17:11 2024 +0200 i386: Implement .SAT_ADD for unsigned scalar integers [PR112600] The following testcase: unsigned add_sat(unsigned x, unsigned y) { unsigned z; return __builtin_add_overflow(x, y, &z) ? -1u : z; } currently compiles (-O2) to: add_sat: addl %esi, %edi jc .L3 movl %edi, %eax ret .L3: orl $-1, %eax ret We can expand through usadd{m}3 optab to use carry flag from the addition and generate branchless code using SBB instruction implementing: unsigned res = x + y; res |= -(res < x); add_sat: addl %esi, %edi sbbl %eax, %eax orl %edi, %eax ret PR target/112600 gcc/ChangeLog: * config/i386/i386.md (usadd<mode>3): New expander. (x86_mov<mode>cc_0_m1_neg): Use SWI mode iterator. gcc/testsuite/ChangeLog: * gcc.target/i386/pr112600-a.c: New test.
