[PATCH v2 1/2] [gdb/symtab] Dump qualified name of cooked_index_entry

[PATCH v2 1/2] [gdb/symtab] Dump qualified name of cooked_index_entry

[Tom de Vries]

When doing "maint print objfiles" for the exec of test-case
gdb.dwarf2/pr13961.exp, we get:
...
    [25] ((cooked_index_entry *) 0x37b25d0)
    name:       foo
    canonical:  foo
    DWARF tag:  DW_TAG_class_type
    flags:      0x0 []
    DIE offset: 0x2a
    parent:     ((cooked_index_entry *) 0)

    [26] ((cooked_index_entry *) 0x37b2630)
    name:       foo
    canonical:  foo
    DWARF tag:  DW_TAG_class_type
    flags:      0x0 []
    DIE offset: 0x25
    parent:     ((cooked_index_entry *) 0x37b25d0) [foo]
...

By following the parent links in the text, we can conclude that the qualified
name of DIE 0x25 is foo::foo (which is incorrect, that's PR symtab/30739).

But it's not evident, and also hard to verify in a test-case.

Add dumping of the qualified name, such that we have:
...
    [25] ((cooked_index_entry *) 0x333b5d0)
    name:       foo
    canonical:  foo
    qualified:  foo
    DWARF tag:  DW_TAG_class_type
    flags:      0x0 []
    DIE offset: 0x2a
    parent:     ((cooked_index_entry *) 0)

    [26] ((cooked_index_entry *) 0x333b630)
    name:       foo
    canonical:  foo
    qualified:  foo::foo
    DWARF tag:  DW_TAG_class_type
    flags:      0x0 []
    DIE offset: 0x25
    parent:     ((cooked_index_entry *) 0x333b5d0) [foo]
...

Tested on x86_64-linux.
---
 gdb/dwarf2/cooked-index.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gdb/dwarf2/cooked-index.c b/gdb/dwarf2/cooked-index.c
index 92ef0e35c5e..351f0016402 100644
--- a/gdb/dwarf2/cooked-index.c
+++ b/gdb/dwarf2/cooked-index.c
@@ -565,6 +565,8 @@ cooked_index::get_main () const
 void
 cooked_index::dump (gdbarch *arch) const
 {
+  auto_obstack temp_storage;
+
   /* Ensure the index is done building.  */
   this->wait ();
 
@@ -579,6 +581,7 @@ cooked_index::dump (gdbarch *arch) const
       gdb_printf ("    [%zu] ((cooked_index_entry *) %p)\n", i++, entry);
       gdb_printf ("    name:       %s\n", entry->name);
       gdb_printf ("    canonical:  %s\n", entry->canonical);
+      gdb_printf ("    qualified:  %s\n", entry->full_name (&temp_storage, false));
       gdb_printf ("    DWARF tag:  %s\n", dwarf_tag_name (entry->tag));
       gdb_printf ("    flags:      %s\n", to_string (entry->flags).c_str ());
       gdb_printf ("    DIE offset: 0x%" PRIx64 "\n",

base-commit: 67bed49ec852aee39172fc867a89ec78c4903883
-- 
2.35.3

[PATCH v2 2/2] [gdb/symtab] Fix off-by-one error in cooked_indexer::recurse

[Tom de Vries]

Test-case gdb.dwarf2/pr13961.exp contains:
...
 <1><25>: Abbrev Number: 8 (DW_TAG_class_type)
    <26>   DW_AT_specification: <0x2a>
 <1><2a>: Abbrev Number: 2 (DW_TAG_class_type)
    <2b>   DW_AT_name        : foo
    <2f>   DW_AT_byte_size   : 4
    <30>   DW_AT_decl_file   : 1
    <31>   DW_AT_decl_line   : 1
    <32>   DW_AT_sibling     : <0x44>
...

The DIE at 0x25 contains an intra-CU forward reference, and is deferred during
DIE indexing in the cooked_index, by adding it to m_deferred_entries.

The resulting cooked index entries are:
...
        [25] ((cooked_index_entry *) 0x333b5d0)
        name:       foo
        canonical:  foo
        qualified:  foo
        DWARF tag:  DW_TAG_class_type
        flags:      0x0 []
        DIE offset: 0x2a
        parent:     ((cooked_index_entry *) 0)

        [26] ((cooked_index_entry *) 0x333b630)
        name:       foo
        canonical:  foo
        qualified:  foo::foo
        DWARF tag:  DW_TAG_class_type
        flags:      0x0 []
        DIE offset: 0x25
        parent:     ((cooked_index_entry *) 0x333b5d0) [foo]
...

Notice that 0x2a is the parent of 0x25, and that this is why the qualified
name of 0x25 is "foo::foo", which is incorrect, it's supposed to be "foo".

The parent is set here in cooked_indexer::make_index:
...
  for (const auto &entry : m_deferred_entries)
    {
      void *obj = m_die_range_map.find (entry.spec_offset);
      cooked_index_entry *parent = static_cast<cooked_index_entry *> (obj);
      m_index_storage->add (entry.die_offset, entry.tag, entry.flags,
			    entry.name, parent, m_per_cu);
    }
...
and AFAICT, we store in m_die_range_map the parent of the respective
spec_offset DIE (though that's not clear from the comment describing it).

So, the root cause of this is that when we lookup the parent for DIE 0x25, we get
m_die_range_map.find (0x2a) == 0x2a.

This is an off-by-one error, fixed in cooked_indexer::recurse by:
...
-      CORE_ADDR start = form_addr (parent_entry->die_offset,
+      CORE_ADDR start = form_addr (parent_entry->die_offset + 1,
...
which gives us:
...
    [12] ((cooked_index_entry *) 0x41e21f0)
    name:       foo
    canonical:  foo
    qualified:  foo
    DWARF tag:  DW_TAG_class_type
    flags:      0x0 []
    DIE offset: 0x25
    parent:     ((cooked_index_entry *) 0)

    [13] ((cooked_index_entry *) 0x41e2190)
    name:       foo
    canonical:  foo
    qualified:  foo
    DWARF tag:  DW_TAG_class_type
    flags:      0x0 []
    DIE offset: 0x2a
    parent:     ((cooked_index_entry *) 0)
...

Tested on x86_64-linux.

PR symtab/30739
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30739
---
 gdb/dwarf2/read.c                    |  4 +++-
 gdb/testsuite/gdb.dwarf2/pr13961.exp | 10 ++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index dd4fac52ca8..a64f82bd24a 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -16477,7 +16477,9 @@ cooked_indexer::recurse (cutu_reader *reader,
 
   if (parent_entry != nullptr)
     {
-      CORE_ADDR start = form_addr (parent_entry->die_offset,
+      /* Both start and end are inclusive, so use both "+ 1" and "- 1" to
+	 limit the range to the children of parent_entry.  */
+      CORE_ADDR start = form_addr (parent_entry->die_offset + 1,
 				   reader->cu->per_cu->is_dwz);
       CORE_ADDR end = form_addr (sect_offset (info_ptr - 1 - reader->buffer),
 				 reader->cu->per_cu->is_dwz);
diff --git a/gdb/testsuite/gdb.dwarf2/pr13961.exp b/gdb/testsuite/gdb.dwarf2/pr13961.exp
index 63c25954b7a..08c38aa3833 100644
--- a/gdb/testsuite/gdb.dwarf2/pr13961.exp
+++ b/gdb/testsuite/gdb.dwarf2/pr13961.exp
@@ -34,3 +34,13 @@ gdb_test "break -q main" "Breakpoint.*at.*"
 
 # If we get this far gdb didn't crash.
 pass $testfile
+
+# Regression test for PR symtab/30739.
+gdb_test_multiple "maint print objfiles $binfile" "no foo::foo" {
+    -re -wrap "\r\n *qualified: *foo::foo\r\n.*" {
+	fail $gdb_test_name
+    }
+    -re -wrap "" {
+	pass $gdb_test_name
+    }
+}
-- 
2.35.3

Re: [PATCH v2 2/2] [gdb/symtab] Fix off-by-one error in cooked_indexer::recurse

[Tom Tromey]

>>>>> "Tom" == Tom de Vries via Gdb-patches <gdb-patches@sourceware.org> writes:

...
Tom> PR symtab/30739
Tom> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30739

Thanks again.
Approved-By: Tom Tromey <tom@tromey.com>

Tom

Re: [PATCH v2 1/2] [gdb/symtab] Dump qualified name of cooked_index_entry

[Tom Tromey]

>>>>> "Tom" == Tom de Vries via Gdb-patches <gdb-patches@sourceware.org> writes:

Tom> But it's not evident, and also hard to verify in a test-case.

Tom> Add dumping of the qualified name, such that we have:
...

Seems reasonable to me.
Approved-By: Tom Tromey <tom@tromey.com>

Tom