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.
