https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106719
Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jakub at gcc dot gnu.org --- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> --- The problem happens during split3. After the splitting but before find_many_sub_basic_blocks we have: ... (jump_insn 10027 10026 10021 2 (set (pc) (if_then_else (ne (reg:SI 2 x2 [100]) (const_int 0 [0])) (label_ref:DI 10022) (pc))) "pr106719.c":7:3 31 {*cbnesi1} (int_list:REG_BR_PROB 536868 (nil)) -> 10022) (note 10021 10027 10016 2 NOTE_INSN_EPILOGUE_BEG) (insn 10016 10021 10017 2 (use (reg:DI 30 x30)) "pr106719.c":9:1 -1 (nil)) (jump_insn 10017 10016 10018 2 (return) "pr106719.c":9:1 28 {*do_return} (nil) -> return) (barrier 10018 10017 10012) (note 10012 10018 10013 NOTE_INSN_DELETED) (note 10013 10012 0 NOTE_INSN_DELETED) at the end for -g0 (--param min-nondebug-insn-uid=10000), while for -g: (jump_insn 10027 10026 4 2 (set (pc) (if_then_else (ne (reg:SI 2 x2 [100]) (const_int 0 [0])) (label_ref:DI 10022) (pc))) "pr106719.c":7:3 31 {*cbnesi1} (int_list:REG_BR_PROB 536868 (nil)) -> 10022) (debug_insn 4 10027 5 2 (debug_marker) "pr106719.c":8:3 -1 (nil)) (debug_insn 5 4 10021 2 (var_location:DI psi (const:DI (plus:DI (symbol_ref:DI ("easi") [flags 0xc0] <var_decl 0x7fffea393f30 easi>) (const_int 1 [0x1])))) "pr106719.c":8:7 -1 (nil)) (note 10021 5 10016 2 NOTE_INSN_EPILOGUE_BEG) (insn 10016 10021 10017 2 (use (reg:DI 30 x30)) "pr106719.c":9:1 -1 (nil)) (jump_insn 10017 10016 10018 2 (return) "pr106719.c":9:1 28 {*do_return} (nil) -> return) (barrier 10018 10017 10012) (note 10012 10018 10013 NOTE_INSN_DELETED) (note 10013 10012 0 NOTE_INSN_DELETED) where jump_insn 10027 is the last one from splitting of (insn:TI 10009 10008 4 2 (parallel [ (set (mem/v:HI (reg/f:DI 0 x0 [94]) [-1 S2 A16]) (unspec_volatile:HI [ (not:HI (and:HI (mem/v:HI (reg/f:DI 0 x0 [94]) [-1 S2 A16]) (reg:HI 1 x1 [orig:98 esi ] [98]))) (const_int 0 [0]) ] UNSPECV_ATOMIC_OP)) (clobber (reg:CC 66 cc)) (clobber (reg:HI 3 x3 [99])) (clobber (reg:SI 2 x2 [100])) ]) "pr106719.c":7:3 4459 {atomic_nandhi} (expr_list:REG_DEAD (reg:HI 1 x1 [orig:98 esi ] [98]) (expr_list:REG_DEAD (reg/f:DI 0 x0 [94]) (expr_list:REG_UNUSED (reg:CC 66 cc) (expr_list:REG_UNUSED (reg:HI 3 x3 [99]) (expr_list:REG_UNUSED (reg:SI 2 x2 [100]) (nil))))))) So, I guess find_many_sub_basic_blocks doesn't ignore DEBUG_INSNs in decisions where to split the basic blocks or something, because we get: (jump_insn 10027 10026 10021 3 (set (pc) (if_then_else (ne (reg:SI 2 x2 [100]) (const_int 0 [0])) (label_ref:DI 10022) (pc))) "pr106719.c":7:3 31 {*cbnesi1} (int_list:REG_BR_PROB 536868 (nil)) -> 10022) (note 10021 10027 10029 NOTE_INSN_EPILOGUE_BEG) (note 10029 10021 10016 4 [bb 4] NOTE_INSN_BASIC_BLOCK) ... in the -g0 case and (jump_insn 10027 10026 10029 3 (set (pc) (if_then_else (ne (reg:SI 2 x2 [100]) (const_int 0 [0])) (label_ref:DI 10022) (pc))) "pr106719.c":7:3 31 {*cbnesi1} (int_list:REG_BR_PROB 536868 (nil)) -> 10022) (note 10029 10027 4 4 [bb 4] NOTE_INSN_BASIC_BLOCK) (debug_insn 4 10029 5 4 (debug_marker) "pr106719.c":8:3 -1 (nil)) (debug_insn 5 4 10021 4 (var_location:DI psi (const:DI (plus:DI (symbol_ref:DI ("easi") [flags 0xc0] <var_decl 0x7fffea393f30 easi>) (const_int 1 [0x1])))) "pr106719.c":8:7 -1 (nil)) (note 10021 5 10016 4 NOTE_INSN_EPILOGUE_BEG) with -g, i.e. appart from the DEBUG_INSNs NOTE_INSN_EPILOGUE_BEG and NOTE_INSN_BASIC_BLOCK notes got swapped.