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* [binutils-gdb] Fix incorrect .gdb_index with new DWARF scanner
@ 2022-10-21 16:13 Tom Tromey
0 siblings, 0 replies; only message in thread
From: Tom Tromey @ 2022-10-21 16:13 UTC (permalink / raw)
To: gdb-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=2afd002ac6acb01763d643686345cc0c6ad564bd
commit 2afd002ac6acb01763d643686345cc0c6ad564bd
Author: Tom Tromey <tromey@adacore.com>
Date: Mon Oct 17 12:21:10 2022 -0600
Fix incorrect .gdb_index with new DWARF scanner
PR symtab/29694 points out a regression caused by the new DWARF
scanner when the cc-with-gdb-index target board is used.
What happens here is that an older version of gdb will make an index
describing the "A" type as:
[737] A: 1 [global, type]
whereas the new gdb says:
[1008] A: 0 [global, type]
Here the old one is correct because the A in CU 0 is just a
declaration without a size:
<1><45>: Abbrev Number: 10 (DW_TAG_structure_type)
<46> DW_AT_name : A
<48> DW_AT_declaration : 1
<48> DW_AT_sibling : <0x6d>
This patch fixes the problem by introducing the idea of a "type
declaration". I think gdb still needs to recurse into these types,
searching for methods, but by marking the type itself as a
declaration, gdb can skip this type during lookups and when writing
the index.
Regression tested on x86-64 using the cc-with-gdb-index board.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29694
Diff:
---
gdb/dwarf2/cooked-index.h | 15 +++++++++++++++
gdb/dwarf2/index-write.c | 5 +++++
gdb/dwarf2/read.c | 22 ++++++++++++++--------
3 files changed, 34 insertions(+), 8 deletions(-)
diff --git a/gdb/dwarf2/cooked-index.h b/gdb/dwarf2/cooked-index.h
index f3c26480a81..2ea32781be5 100644
--- a/gdb/dwarf2/cooked-index.h
+++ b/gdb/dwarf2/cooked-index.h
@@ -48,6 +48,9 @@ enum cooked_index_flag_enum : unsigned char
IS_ENUM_CLASS = 4,
/* True if this entry uses the linkage name. */
IS_LINKAGE = 8,
+ /* True if this entry is just for the declaration of a type, not the
+ definition. */
+ IS_TYPE_DECLARATION = 16,
};
DEF_ENUM_FLAGS_TYPE (enum cooked_index_flag_enum, cooked_index_flag);
@@ -76,6 +79,10 @@ struct cooked_index_entry : public allocate_on_obstack
/* Return true if this entry matches SEARCH_FLAGS. */
bool matches (block_search_flags search_flags) const
{
+ /* Just reject type declarations. */
+ if ((flags & IS_TYPE_DECLARATION) != 0)
+ return false;
+
if ((search_flags & SEARCH_STATIC_BLOCK) != 0
&& (flags & IS_STATIC) != 0)
return true;
@@ -88,6 +95,10 @@ struct cooked_index_entry : public allocate_on_obstack
/* Return true if this entry matches DOMAIN. */
bool matches (domain_enum domain) const
{
+ /* Just reject type declarations. */
+ if ((flags & IS_TYPE_DECLARATION) != 0)
+ return false;
+
switch (domain)
{
case LABEL_DOMAIN:
@@ -106,6 +117,10 @@ struct cooked_index_entry : public allocate_on_obstack
/* Return true if this entry matches KIND. */
bool matches (enum search_domain kind) const
{
+ /* Just reject type declarations. */
+ if ((flags & IS_TYPE_DECLARATION) != 0)
+ return false;
+
switch (kind)
{
case VARIABLES_DOMAIN:
diff --git a/gdb/dwarf2/index-write.c b/gdb/dwarf2/index-write.c
index f592734addc..3d215a6307b 100644
--- a/gdb/dwarf2/index-write.c
+++ b/gdb/dwarf2/index-write.c
@@ -1167,6 +1167,11 @@ write_cooked_index (cooked_index_vector *table,
be redundant are rare and not worth supporting. */
continue;
}
+ else if ((entry->flags & IS_TYPE_DECLARATION) != 0)
+ {
+ /* Don't add type declarations to the index. */
+ continue;
+ }
gdb_index_symbol_kind kind;
if (entry->tag == DW_TAG_subprogram)
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 7de89dd5923..cde7a5bd01f 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -18191,14 +18191,20 @@ cooked_indexer::scan_attributes (dwarf2_per_cu_data *scanning_per_cu,
that is ok. Similarly, we allow an external variable without a
location; those are resolved via minimal symbols. */
if (is_declaration && !for_specification
- && !(abbrev->tag == DW_TAG_variable && (*flags & IS_STATIC) == 0)
- && !((abbrev->tag == DW_TAG_class_type
- || abbrev->tag == DW_TAG_structure_type
- || abbrev->tag == DW_TAG_union_type)
- && abbrev->has_children))
- {
- *linkage_name = nullptr;
- *name = nullptr;
+ && !(abbrev->tag == DW_TAG_variable && (*flags & IS_STATIC) == 0))
+ {
+ /* We always want to recurse into some types, but we may not
+ want to treat them as definitions. */
+ if ((abbrev->tag == DW_TAG_class_type
+ || abbrev->tag == DW_TAG_structure_type
+ || abbrev->tag == DW_TAG_union_type)
+ && abbrev->has_children)
+ *flags |= IS_TYPE_DECLARATION;
+ else
+ {
+ *linkage_name = nullptr;
+ *name = nullptr;
+ }
}
else if ((*name == nullptr
|| (*linkage_name == nullptr
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