From: Tom de Vries <tdevries@suse.de>
To: gdb-patches@sourceware.org
Cc: Tom Tromey <tom@tromey.com>
Subject: [PATCH v2 2/2] [gdb/symtab] Fix off-by-one error in cooked_indexer::recurse
Date: Thu, 10 Aug 2023 18:07:58 +0200 [thread overview]
Message-ID: <20230810160758.9760-2-tdevries@suse.de> (raw)
In-Reply-To: <20230810160758.9760-1-tdevries@suse.de>
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
next prev parent reply other threads:[~2023-08-10 16:08 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-10 16:07 [PATCH v2 1/2] [gdb/symtab] Dump qualified name of cooked_index_entry Tom de Vries
2023-08-10 16:07 ` Tom de Vries [this message]
2023-08-10 17:46 ` [PATCH v2 2/2] [gdb/symtab] Fix off-by-one error in cooked_indexer::recurse Tom Tromey
2023-08-10 17:46 ` [PATCH v2 1/2] [gdb/symtab] Dump qualified name of cooked_index_entry Tom Tromey
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