[Bug default/27213] New: alt_clear_dups: Assertion `child->die_dup == NULL' failed.

[Bug default/27213] New: alt_clear_dups: Assertion `child->die_dup == NULL' failed.

[jakub at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27213

            Bug ID: 27213
           Summary: alt_clear_dups: Assertion `child->die_dup == NULL'
                    failed.
           Product: dwz
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: default
          Assignee: nobody at sourceware dot org
          Reporter: jakub at redhat dot com
                CC: dwz at sourceware dot org
  Target Milestone: ---

Created attachment 13137
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13137&action=edit
tarball with g++ gcc ar nm built with DWARF5 .debug_info and .debug_line

for i in g++ gcc ar nm; do cp -af $i.orig $i; done; rm -f gcc.dwz; ./dwz -m
gcc.dwz g++ gcc ar nm
dwz: dwz.c:15837: alt_clear_dups: Assertion `child->die_dup == NULL' failed.
Aborted (core dumped)

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[Bug default/27213] alt_clear_dups: Assertion `child->die_dup == NULL' failed.

[mark at klomp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27213

Mark Wielaard <mark at klomp dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mark at klomp dot org

--- Comment #1 from Mark Wielaard <mark at klomp dot org> ---
It doesn't help with this case. But reviewing the code I found that there was
at least one place where we didn't hash the DW_FORM_implicit_const value in
checksum_die meaning that two DIEs which only differed in an attribute (which
we didn't already handle specially) using a DW_FORM_implicit_const with a
different value (maybe a DW_AT_byte_size) could possibly hash to the same
value.

diff --git a/dwz.c b/dwz.c
index 308bcba..e556dfb 100644
--- a/dwz.c
+++ b/dwz.c
@@ -3580,7 +3580,11 @@ checksum_die (DSO *dso, dw_cu_ref cu, dw_die_ref
top_die, dw_die_ref die)
          ptr += ptr_size;
          break;
        case DW_FORM_flag_present:
+         break;
        case DW_FORM_implicit_const:
+         if (! handled)
+           die->u.p1.die_hash
+             = iterative_hash_object (t->values[i], die->u.p1.die_hash);
          break;
        case DW_FORM_flag:
        case DW_FORM_data1:

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[Bug default/27213] alt_clear_dups: Assertion `child->die_dup == NULL' failed.

[jakub at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27213

--- Comment #2 from Jakub Jelinek <jakub at redhat dot com> ---
Apparently the #27212 fix also fixes the Assertion failure.

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[Bug default/27213] alt_clear_dups: Assertion `child->die_dup == NULL' failed.

[jakub at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27213

--- Comment #3 from Jakub Jelinek <jakub at redhat dot com> ---
(In reply to Mark Wielaard from comment #1)
> It doesn't help with this case. But reviewing the code I found that there
> was at least one place where we didn't hash the DW_FORM_implicit_const value
> in checksum_die meaning that two DIEs which only differed in an attribute
> (which we didn't already handle specially) using a DW_FORM_implicit_const
> with a different value (maybe a DW_AT_byte_size) could possibly hash to the
> same value.
> 
> diff --git a/dwz.c b/dwz.c
> index 308bcba..e556dfb 100644
> --- a/dwz.c
> +++ b/dwz.c
> @@ -3580,7 +3580,11 @@ checksum_die (DSO *dso, dw_cu_ref cu, dw_die_ref
> top_die, dw_die_ref die)
>           ptr += ptr_size;
>           break;
>         case DW_FORM_flag_present:
> +         break;
>         case DW_FORM_implicit_const:
> +         if (! handled)
> +           die->u.p1.die_hash
> +             = iterative_hash_object (t->values[i], die->u.p1.die_hash);
>           break;
>         case DW_FORM_flag:
>         case DW_FORM_data1:

As for this patch, I agree that something should be done about it,
but wonder if it shouldn't be
          if (!handled && die->die_ck_state != CK_BAD)
            {
              handled = true;
              die->u.p1.die_hash
                = iterative_hash_object (t->values[i], die->u.p1.die_hash);
            }

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[Bug default/27213] alt_clear_dups: Assertion `child->die_dup == NULL' failed.

[jakub at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27213

--- Comment #4 from Jakub Jelinek <jakub at redhat dot com> ---
Another thing I'm worried about, where in die_eq_1 we compare the
DW_FORM_implicit_const values?
I wonder about:
        case DW_FORM_flag_present:
          break;
        case DW_FORM_implicit_const:
          if ((!ignore_locus || old_ptr1)
              && t1->values[i] != t2->values[j])
            FAIL;
          break;
in die_eq_1.

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[Bug default/27213] alt_clear_dups: Assertion `child->die_dup == NULL' failed.

[jakub at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27213

--- Comment #5 from Jakub Jelinek <jakub at redhat dot com> ---
So:
diff --git a/dwz.c b/dwz.c
index 308bcba..a6ea5ec 100644
--- a/dwz.c
+++ b/dwz.c
@@ -3580,7 +3580,14 @@ checksum_die (DSO *dso, dw_cu_ref cu, dw_die_ref
top_die, dw_die_ref die)
          ptr += ptr_size;
          break;
        case DW_FORM_flag_present:
+         break;
        case DW_FORM_implicit_const:
+         if (!handled && die->die_ck_state != CK_BAD)
+           {
+             handled = true;
+             die->u.p1.die_hash
+               = iterative_hash_object (t->values[i], die->u.p1.die_hash);
+           }
          break;
        case DW_FORM_flag:
        case DW_FORM_data1:
@@ -4837,7 +4844,11 @@ die_eq_1 (dw_cu_ref cu1, dw_cu_ref cu2,
          ptr2 += ptr_size;
          break;
        case DW_FORM_flag_present:
+         break;
        case DW_FORM_implicit_const:
+         if ((!ignore_locus || old_ptr1)
+             && t1->values[i] != t2->values[j])
+           FAIL;
          break;
        case DW_FORM_flag:
        case DW_FORM_data1:
@@ -10456,19 +10467,18 @@ build_abbrevs_for_die (htab_t h, dw_cu_ref cu,
dw_die_ref die,
                    case DW_FORM_data4: value = read_32 (ptr); break;
                    case DW_FORM_data8: value = read_64 (ptr); break;
                    case DW_FORM_udata: value = read_uleb128 (ptr); break;
-                   case DW_FORM_implicit_const: break;
+                   case DW_FORM_implicit_const:
+                     value = reft->values[i];
+                     break;
                    default:
                      error (0, 0, "Unhandled %s for %s",
                             get_DW_FORM_str (form),
                             get_DW_AT_str (reft->attr[i].attr));
                      return 1;
                    }
-                 /* Note that the value is only used for calculating the
-                    DIE size and possibly change form. Doesn't change the
-                    implicit_const from or value.  */
+                 value = line_htab_lookup (refcu, value);
                  if (form != DW_FORM_implicit_const)
                    {
-                     value = line_htab_lookup (refcu, value);
                      if (value <= 0xff)
                        {
                          form = DW_FORM_data1;
@@ -10488,7 +10498,7 @@ build_abbrevs_for_die (htab_t h, dw_cu_ref cu,
dw_die_ref die,
                  t->attr[j].attr = reft->attr[i].attr;
                  t->attr[j].form = form;
                  if (form == DW_FORM_implicit_const)
-                   t->values[j] = reft->values[i];
+                   t->values[j] = value;
                  j++;
                  continue;
                }
@@ -12088,10 +12098,8 @@ write_die (unsigned char *ptr, dw_cu_ref cu,
dw_die_ref die,
                  update = true;
                  break;
                case DW_FORM_implicit_const:
-                 /* Negative means, already transformed.  */
-                 if (reft->values[i] >= 0)
-                   update = true;
-                 value = reft->values[i];
+                 /* DW_FORM_implicit_const should have been updated
+                    already when computing abbrevs.  */
                  break;
                default: abort ();
                }
@@ -12104,9 +12112,6 @@ write_die (unsigned char *ptr, dw_cu_ref cu, dw_die_ref
die,
                    case DW_FORM_data2: write_16 (ptr, value); break;
                    case DW_FORM_data4: write_32 (ptr, value); break;
                    case DW_FORM_udata: write_uleb128 (ptr, value); break;
-                   case DW_FORM_implicit_const:
-                     reft->values[i] = -value; /* Note, negated.  */
-                     break;
                    default: abort ();
                    }
                }
as the full patch?

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[Bug default/27213] alt_clear_dups: Assertion `child->die_dup == NULL' failed.

[mark at klomp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27213

--- Comment #6 from Mark Wielaard <mark at klomp dot org> ---
(In reply to Jakub Jelinek from comment #3)
> As for this patch, I agree that something should be done about it,
> but wonder if it shouldn't be
>           if (!handled && die->die_ck_state != CK_BAD)
>             {
>               handled = true;
>               die->u.p1.die_hash
>                 = iterative_hash_object (t->values[i], die->u.p1.die_hash);
>             }

Yes, checking for CK_BAD is correct. Thanks.

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[Bug default/27213] alt_clear_dups: Assertion `child->die_dup == NULL' failed.

[mark at klomp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27213

--- Comment #7 from Mark Wielaard <mark at klomp dot org> ---
(In reply to Jakub Jelinek from comment #4)
> Another thing I'm worried about, where in die_eq_1 we compare the
> DW_FORM_implicit_const values?
> I wonder about:
>         case DW_FORM_flag_present:
>           break;
>         case DW_FORM_implicit_const:
>           if ((!ignore_locus || old_ptr1)
>               && t1->values[i] != t2->values[j])
>             FAIL;
>           break;
> in die_eq_1.

Yes, I was just looking at that one. It would make checksum_die and die_eq
agree with each other. Looks correct.

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[Bug default/27213] alt_clear_dups: Assertion `child->die_dup == NULL' failed.

[jakub at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27213

--- Comment #8 from Jakub Jelinek <jakub at redhat dot com> ---
author  Jakub Jelinek <jakub@redhat.com>        
        Thu, 21 Jan 2021 07:43:08 +0000 (08:43 +0100)
committer       Jakub Jelinek <jakub@redhat.com>        
        Thu, 21 Jan 2021 07:43:08 +0000 (08:43 +0100)
commit  47af8da7c8533924e96d1dbd97625b6a4dc35855
tree    4a924fd99e9ee98dcc4125836309dff06de39b19        tree
parent  40d5efd4edc52a7d2ed02f8400a9beb129053271        commit | diff
Assorted DW_FORM_implicit_const fixes

The problem is I think that write_abbrev is always called before write_info,
and the remapping of the DW_AT_decl_file/DW_AT_call_file DW_FORM_implicit_const
is done only in write_die which is called either recursively or from
write_info/write_types.  Which means the DW_FORM_implicit_const value encoded
in the abbrev was never updated.

Other fixes include hashing the DW_FORM_implicit_const value in checksum_die
and more importantly comparing the values in die_eq_1.

2021-01-21  Jakub Jelinek  <jakub@redhat.com>

PR dwz/27212
PR dwz/27213
* dwz.c (checksum_die): For DW_FORM_implicit_const hash t->values[i].
(die_eq_1): For DW_FORM_implicit_const compare t?->values[?].
(build_abbrevs_for_die): For DW_FORM_implicit_const on DW_AT_*_file
call line_htab_lookup too and store the result into t->values[j].
Otherwise, handle even file ids larger than 32-bit.
(write_die): For DW_FORM_implicit_const on DW_AT_*_file just j++
and continue, don't call line_htab_lookup nor adjust anything.
Simplify.
(alt_clear_dups): Fix function comment.

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[Bug default/27213] alt_clear_dups: Assertion `child->die_dup == NULL' failed.

[mark at klomp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27213

Mark Wielaard <mark at klomp dot org> changed:

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

--- Comment #9 from Mark Wielaard <mark at klomp dot org> ---
Fixed by the commit from comment #8.

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