[Bug target/106719] [10/11/12/13 Regression] '-fcompare-debug' failure w/ -O2 since r10-6038-ge5e07b68187b9a

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

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.