[Bug default/24204] [dwz, low-mem] Couldn't find DIE referenced by DW_OP_GNU_implicit_pointer

[Bug default/24204] [dwz, low-mem] Couldn't find DIE referenced by DW_OP_GNU_implicit_pointer

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=24204

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
Patch submitted: https://sourceware.org/ml/dwz/2019-q1/msg00020.html

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[Bug default/24204] [dwz, low-mem] Couldn't find DIE referenced by DW_OP_GNU_implicit_pointer

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=24204

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at redhat dot com

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
AFAIU, the problem is as follows:

During the first low-mem phase in read_debug_info, we're supposed to read in
all the intercu-referenced DIES, such that they're available during the second
phase.

But in read_debug_info, we're just skipping over the DW_FORM_exprloc that
points to the location list that contains the DW_OP_GNU_implicit_pointer
reference to the DW_TAG_dwarf_procedure DIE:
...
                case DW_FORM_exprloc:
                  len = read_uleb128 (ptr);
                  form = DW_FORM_block1;
                  break;
...

And consequently, when we try to access the DIE in checksum_die, it's not
available.

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[Bug default/24204] New: [dwz, low-mem] Couldn't find DIE referenced by DW_OP_GNU_implicit_pointer

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=24204

            Bug ID: 24204
           Summary: [dwz, low-mem] Couldn't find DIE referenced by
                    DW_OP_GNU_implicit_pointer
           Product: dwz
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: default
          Assignee: nobody at sourceware dot org
          Reporter: vries at gcc dot gnu.org
                CC: dwz at sourceware dot org
  Target Milestone: ---

Using the cc1 from pr24195, and the tentative fix we produce cc1.2:
...
$ dwz -l 0 cc1 -o cc1.2
...

Then with master we run into:
...
$ dwz -l 0 cc1.2
dwz: cc1: Couldn't find DIE referenced by DW_OP_GNU_implicit_pointer
...

Using a more detailed error message, we get:
...
dwz: cc1: Couldn't find DIE@0x800 referenced by DW_OP_GNU_implicit_pointer in
DIE@0x369186
...

The die is:
...
 <12><369186>: Abbrev Number: 3 (DW_TAG_formal_parameter)
    <369187>   DW_AT_abstract_origin: <0xecc97>
    <36918b>   DW_AT_location    : 0x4ee259 (location list)
    <36918f>   DW_AT_GNU_locviews: 0x4ee255
...

Referring to locviews and location list:
...
    004ee255 v000000000000004 v000000000000001 location view pair
    004ee257 v000000000000000 v000000000000000 location view pair

    004ee259 v000000000000004 v000000000000001 views at 004ee255 for:
             0000000000876020 000000000087602b (DW_OP_GNU_implicit_pointer:
<0x800> 0)
    004ee271 v000000000000000 v000000000000000 views at 004ee257 for:
             0000000000587ca8 0000000000587cb0 (DW_OP_GNU_implicit_pointer:
<0x800> 0)
    004ee289 <End of list>
...

which refer to DIE:
...
 <1><800>: Abbrev Number: 112 (DW_TAG_dwarf_procedure)
    <801>   DW_AT_location    : 21 byte block: 9e 13 66 69 72 73 74 5f 69 6d 6d
5f 75 73 65 5f 73 74 6d 74 0    (DW_OP_implicit_value 19 byte block: 66 69 72
73 74 5f 69 6d 6d 5f 75 73 65 5f 73 74 6d 74 0 )
...

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[Bug default/24204] [dwz, low-mem] Couldn't find DIE referenced by DW_OP_GNU_implicit_pointer

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=24204

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
https://sourceware.org/git/?p=dwz.git;a=commit;h=bf6ad3abd3a61fe6972b08e238b2b3bdf507e971

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