https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88540
--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:9f8f37f5490076b10436993fb90d18092a960922 commit r14-2699-g9f8f37f5490076b10436993fb90d18092a960922 Author: Richard Biener <rguent...@suse.de> Date: Thu Jul 13 08:58:58 2023 +0200 tree-optimization/88540 - FP x > y ? x : y if-conversion without -ffast-math The following makes sure that FP x > y ? x : y style max/min operations are if-converted at the GIMPLE level. While we can neither match it to MAX_EXPR nor .FMAX as both have different semantics with IEEE than the ternary ?: operation we can make sure to maintain this form as a COND_EXPR so backends have the chance to match this to instructions their ISA offers. The patch does this in phiopt where we recognize min/max and instead of giving up when we have to honor NaNs we alter the generated code to a COND_EXPR. This resolves PR88540 and we can then SLP vectorize the min operation for its testcase. It also resolves part of the regressions observed with the change matching bit-inserts of bit-field-refs to vec_perm. Expansion from a COND_EXPR rather than from compare-and-branch gcc.target/i386/pr54855-9.c by producing extra moves while the corresponding min/max operations are now already synthesized by RTL expansion, register selection isn't optimal. This can be also provoked without this change by altering the operand order in the source. I have XFAILed that part of the test. PR tree-optimization/88540 * tree-ssa-phiopt.cc (minmax_replacement): Do not give up with NaNs but handle the simple case by if-converting to a COND_EXPR. * gcc.target/i386/pr88540.c: New testcase. * gcc.target/i386/pr54855-9.c: XFAIL check for redundant moves. * gcc.target/i386/pr54855-12.c: Adjust. * gcc.target/i386/pr54855-13.c: Likewise. * gcc.target/i386/pr110170.c: Likewise. * gcc.dg/tree-ssa/split-path-12.c: Likewise.
