[Bug debug/68860] [6/7 regression] FAIL: gcc.dg/guality/pr36728-1.c -flto -O3 -g line 16/7 arg1 == 1

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68860

--- Comment #15 from Richard Biener <rguenth at gcc dot gnu.org> ---
So with LTO early debug I now get proper debug decls but still no locations for
the parameters

 <1><1ff>: Abbrev Number: 10 (DW_TAG_subprogram)
    <200>   DW_AT_abstract_origin: <0x28b>
    <204>   DW_AT_low_pc      : 0x400570
    <20c>   DW_AT_high_pc     : 0x47
    <214>   DW_AT_frame_base  : 1 byte block: 9c        (DW_OP_call_frame_cfa)
    <216>   DW_AT_GNU_all_call_sites: 1
 <2><216>: Abbrev Number: 11 (DW_TAG_formal_parameter)
    <217>   DW_AT_abstract_origin: <0x2dc>
    <21b>   DW_AT_location    : 0x37 (location list)
 <2><21f>: Abbrev Number: 4 (DW_TAG_formal_parameter)
    <220>   DW_AT_abstract_origin: <0x2d1>
 <2><224>: Abbrev Number: 4 (DW_TAG_formal_parameter)
    <225>   DW_AT_abstract_origin: <0x2c6>
...

vs. non-LTO -O2:

 <1><282>: Abbrev Number: 13 (DW_TAG_subprogram)
    <283>   DW_AT_abstract_origin: <0x1fa>
    <287>   DW_AT_low_pc      : 0x400570
    <28f>   DW_AT_high_pc     : 0x47
    <297>   DW_AT_frame_base  : 1 byte block: 9c        (DW_OP_call_frame_cfa)
    <299>   DW_AT_GNU_all_call_sites: 1
 <2><299>: Abbrev Number: 14 (DW_TAG_formal_parameter)
    <29a>   DW_AT_abstract_origin: <0x24c>
    <29e>   DW_AT_location    : 0x37 (location list)
 <2><2a2>: Abbrev Number: 15 (DW_TAG_formal_parameter)
    <2a3>   DW_AT_abstract_origin: <0x241>
    <2a7>   DW_AT_location    : 6 byte block: fa e6 0 0 0 9f   
(DW_OP_GNU_parameter_ref: <0x241>; DW_OP_stack_value)


the .optimized GIMPLE looks the same (and early LTO debug does stream
DECL_ABSTRACT_ORIGIN).  var-tracking only has NOTE_INSN_VAR_LOCATION for arg7
though.  Initial RTL looks the same:

;; # DEBUG arg2 s=> arg2

(debug_insn 8 7 0 (var_location:SI arg2 (const_int 0 [0]) [uninit]) -1
     (nil))
...

Looks like var-tracking misses to add all

(note 63 62 64 2 (var_location arg1 (debug_parameter_ref:SI arg1))
NOTE_INSN_VAR_LOCATION)
(note 64 63 65 2 (var_location arg2 (debug_parameter_ref:SI arg2))
NOTE_INSN_VAR_LOCATION)
(note 65 64 66 2 (var_location arg3 (debug_parameter_ref:SI arg3))
NOTE_INSN_VAR_LOCATION)
(note 66 65 67 2 (var_location arg4 (debug_parameter_ref:SI arg4))
NOTE_INSN_VAR_LOCATION)
(note 67 66 68 2 (var_location arg5 (debug_parameter_ref:SI arg5))
NOTE_INSN_VAR_LOCATION)
(note 68 67 44 2 (var_location arg6 (debug_parameter_ref:SI arg6))
NOTE_INSN_VAR_LOCATION)

ah, because DECL_HAS_DEBUG_ARGS_P and friends has not been LTOed yet.