https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82692
Uroš Bizjak <ubizjak at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2017-10-24 Ever confirmed|0 |1 --- Comment #1 from Uroš Bizjak <ubizjak at gmail dot com> --- Happens in combine: (insn 7 6 8 2 (set (reg:CCFPU 17 flags) (compare:CCFPU (reg:DF 95) (reg/v:DF 91 [ x ]))) "pr82692.c":9 52 {*cmpiudf} (expr_list:REG_DEAD (reg:DF 95) (expr_list:REG_EQUAL (compare:CCFPU (const_double:DF 0.0 [0x0.0p+0]) (reg/v:DF 91 [ x ])) (nil)))) (insn 8 7 9 2 (set (reg:QI 94) (unlt:QI (reg:CCFPU 17 flags) (const_int 0 [0]))) "pr82692.c":9 664 {*setcc_qi} (expr_list:REG_DEAD (reg:CCFPU 17 flags) (nil))) (insn 9 8 10 2 (set (reg:CCZ 17 flags) (compare:CCZ (reg:QI 94) (const_int 0 [0]))) "pr82692.c":9 1 {*cmpqi_ccno_1} (expr_list:REG_DEAD (reg:QI 94) (nil))) combines to: Trying 8 -> 9: Failed to match this instruction: (set (reg:CCFPU 17 flags) (reg:CCFPU 17 flags)) Successfully matched this instruction: (set (pc) (if_then_else (ge (reg:CCFPU 17 flags) (const_int 0 [0])) (label_ref:DI 34) (pc))) Trying 7 -> 9: Successfully matched this instruction: (set (reg:CCFP 17 flags) (compare:CCFP (reg:DF 95) (reg/v:DF 91 [ x ]))) Successfully matched this instruction: (set (pc) (if_then_else (ge (reg:CCFP 17 flags) (const_int 0 [0])) (label_ref:DI 34) (pc)))