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From: "vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
To: dwz@sourceware.org
Subject: [Bug default/27418] New: DW_FORM_implicit_const handling in
 checksum_die missing attribute hashing
Date: Sun, 14 Feb 2021 21:33:32 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D27418

            Bug ID: 27418
           Summary: DW_FORM_implicit_const handling in checksum_die
                    missing attribute hashing
           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: ---

This is something that I don't get:
...
        case DW_FORM_implicit_const:
          if (!handled && die->die_ck_state !=3D CK_BAD)
            {
              handled =3D true;
              die->u.p1.die_hash
                =3D iterative_hash_object (t->values[i], die->u.p1.die_hash=
);
            }
          break;
...

Normally, we have something like:
...
              s =3D t->attr[i].attr;
              die->u.p1.die_hash
                =3D iterative_hash_object (s, die->u.p1.die_hash);
              die->u.p1.die_hash
                =3D iterative_hash_object (value, die->u.p1.die_hash);
...
so we hash in both the attribute tag and the attribute value.

Why don't we hash in the attribute tag for DW_FORM_implicit_const?

This sound like a bug that makes hash collisions more likely.

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