https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51492
--- Comment #19 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Pan Li <pa...@gcc.gnu.org>: https://gcc.gnu.org/g:52b0536710ff3f3ace72ab00ce9ef6c630cd1183 commit r15-576-g52b0536710ff3f3ace72ab00ce9ef6c630cd1183 Author: Pan Li <pan2...@intel.com> Date: Wed May 15 10:14:05 2024 +0800 Internal-fn: Support new IFN SAT_ADD for unsigned scalar int This patch would like to add the middle-end presentation for the saturation add. Aka set the result of add to the max when overflow. It will take the pattern similar as below. SAT_ADD (x, y) => (x + y) | (-(TYPE)((TYPE)(x + y) < x)) Take uint8_t as example, we will have: * SAT_ADD (1, 254) => 255. * SAT_ADD (1, 255) => 255. * SAT_ADD (2, 255) => 255. * SAT_ADD (255, 255) => 255. Given below example for the unsigned scalar integer uint64_t: uint64_t sat_add_u64 (uint64_t x, uint64_t y) { return (x + y) | (- (uint64_t)((uint64_t)(x + y) < x)); } Before this patch: uint64_t sat_add_uint64_t (uint64_t x, uint64_t y) { long unsigned int _1; _Bool _2; long unsigned int _3; long unsigned int _4; uint64_t _7; long unsigned int _10; __complex__ long unsigned int _11; ;; basic block 2, loop depth 0 ;; pred: ENTRY _11 = .ADD_OVERFLOW (x_5(D), y_6(D)); _1 = REALPART_EXPR <_11>; _10 = IMAGPART_EXPR <_11>; _2 = _10 != 0; _3 = (long unsigned int) _2; _4 = -_3; _7 = _1 | _4; return _7; ;; succ: EXIT } After this patch: uint64_t sat_add_uint64_t (uint64_t x, uint64_t y) { uint64_t _7; ;; basic block 2, loop depth 0 ;; pred: ENTRY _7 = .SAT_ADD (x_5(D), y_6(D)); [tail call] return _7; ;; succ: EXIT } The below tests are passed for this patch: 1. The riscv fully regression tests. 3. The x86 bootstrap tests. 4. The x86 fully regression tests. PR target/51492 PR target/112600 gcc/ChangeLog: * internal-fn.cc (commutative_binary_fn_p): Add type IFN_SAT_ADD to the return true switch case(s). * internal-fn.def (SAT_ADD): Add new signed optab SAT_ADD. * match.pd: Add unsigned SAT_ADD match(es). * optabs.def (OPTAB_NL): Remove fixed-point limitation for us/ssadd. * tree-ssa-math-opts.cc (gimple_unsigned_integer_sat_add): New extern func decl generated in match.pd match. (match_saturation_arith): New func impl to match the saturation arith. (math_opts_dom_walker::after_dom_children): Try match saturation arith when IOR expr. Signed-off-by: Pan Li <pan2...@intel.com>