https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111594
Bug ID: 111594 Summary: RISC-V: Failed to fold VEC_COND_EXPR and COND_LEN_ADD Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: juzhe.zhong at rivai dot ai Target Milestone: --- Consider this following case: #include <stdint.h> void single_loop_with_if_condition(uint64_t * restrict a, uint64_t * restrict b, int loop_size) { uint64_t result = 0; for (int i = 0; i < loop_size; i++) { if (b[i] <= a[i]) { result += a[i]; } } a[0] = result; } In ARM SVE: vect__ifc__33.15_48 = VEC_COND_EXPR <mask__18.14_46, vect__7.13_45, { 0, ... }>; vect__34.16_49 = .COND_ADD (loop_mask_41, vect_result_19.7_38, vect__ifc__33.15_48, vect_result_19.7_38); will be folded into: vect__34.16_49 = .COND_ADD (_50, vect_result_19.7_38, vect__7.13_45, vect_result_19.7_38); However, for RVV, if failed to fold VEC_COND_EXPR + COND_LEN_ADD. vect__ifc__44.30_96 = VEC_COND_EXPR <mask__43.29_94, vect__42.28_93, { 0, ... }>; vect__45.31_97 = .COND_LEN_ADD ({ -1, ... }, vect_result_35.22_78, vect__ifc__44.30_96, vect_result_35.22_78, _104, 0); I am not sure where to do this optimization?