Add name canonicalization for C
PR symtab/29105 shows a number of situations where symbol lookup can
result in the expansion of too many CUs.
What happens is that lookup_signed_typename will try to look up a type
like "signed int". In cooked_index_functions::expand_symtabs_matching,
when looping over languages, the C++ case will canonicalize this type
name to be "int" instead. Then this method will proceed to expand
every CU that has an entry for "int" -- i.e., nearly all of them. A
crucial component of this is that the caller, objfile::lookup_symbol,
does not do this canonicalization, so when it tries to find the symbol
for "signed int", it fails -- causing the loop to continue.
This patch fixes the problem by introducing name canonicalization for
C. The idea here is that, by making C and C++ agree on the canonical
name when a symbol name can have multiple spellings, we avoid the bad
behavior in objfile::lookup_symbol (and any other such code -- I don't
know if there is any).
Unlike C++, C only has a few situations where canonicalization is
needed. And, in particular, due to the lack of overloading (thus
avoiding any issues in linespec) and due to the way c-exp.y works, I
think that no canonicalization is needed during symbol lookup -- only
during symtab construction. This explains why lookup_name_info is not
touched.
The stabs reader is modified on a "best effort" basis.
The DWARF reader needed one small tweak in dwarf2_name to avoid a
regression in dw2-unusual-field-names.exp. I think this is adequately
explained by the comment, but basically this is a scenario that should
not occur in real code, only the gdb test suite.
lookup_signed_typename is simplified. It used to search for two
different type names, but now gdb can search just for the canonical
form.
gdb.dwarf2/enum-type.exp needed a small tweak, because the
canonicalizer turns "unsigned integer" into "unsigned int integer".
It seems better here to use the correct C type name.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29105
Tested-by: Simon Marchi <simark@simark.ca>
Reviewed-by: Andrew Burgess <aburgess@redhat.com>
diff --git a/gdb/c-lang.c b/gdb/c-lang.c
index e15541f..46c0da0 100644
--- a/gdb/c-lang.c
+++ b/gdb/c-lang.c
@@ -727,6 +727,20 @@ c_is_string_type_p (struct type *type)
+/* See c-lang.h. */
+
+gdb::unique_xmalloc_ptr<char>
+c_canonicalize_name (const char *name)
+{
+ if (strchr (name, ' ') != nullptr
+ || streq (name, "signed")
+ || streq (name, "unsigned"))
+ return cp_canonicalize_string (name);
+ return nullptr;
+}
+
+
+
void
c_language_arch_info (struct gdbarch *gdbarch,
struct language_arch_info *lai)
diff --git a/gdb/c-lang.h b/gdb/c-lang.h
index 9351567..652f147 100644
--- a/gdb/c-lang.h
+++ b/gdb/c-lang.h
@@ -167,4 +167,9 @@ extern std::string cplus_compute_program (compile_instance *inst,
const struct block *expr_block,
CORE_ADDR expr_pc);
+/* Return the canonical form of the C symbol NAME. If NAME is already
+ canonical, return nullptr. */
+
+extern gdb::unique_xmalloc_ptr<char> c_canonicalize_name (const char *name);
+
#endif /* !defined (C_LANG_H) */
diff --git a/gdb/dbxread.c b/gdb/dbxread.c
index b0047cf..ae726bd 100644
--- a/gdb/dbxread.c
+++ b/gdb/dbxread.c
@@ -48,6 +48,7 @@
#include "complaints.h"
#include "cp-abi.h"
#include "cp-support.h"
+#include "c-lang.h"
#include "psympriv.h"
#include "block.h"
#include "aout/aout64.h"
@@ -1444,6 +1445,18 @@ read_dbx_symtab (minimal_symbol_reader &reader,
new_name.get ());
}
}
+ else if (psymtab_language == language_c)
+ {
+ std::string name (namestring, p - namestring);
+ gdb::unique_xmalloc_ptr<char> new_name
+ = c_canonicalize_name (name.c_str ());
+ if (new_name != nullptr)
+ {
+ sym_len = strlen (new_name.get ());
+ sym_name = obstack_strdup (&objfile->objfile_obstack,
+ new_name.get ());
+ }
+ }
if (sym_len == 0)
{
diff --git a/gdb/dwarf2/cooked-index.c b/gdb/dwarf2/cooked-index.c
index a580d54..0aa026c 100644
--- a/gdb/dwarf2/cooked-index.c
+++ b/gdb/dwarf2/cooked-index.c
@@ -21,6 +21,7 @@
#include "dwarf2/cooked-index.h"
#include "dwarf2/read.h"
#include "cp-support.h"
+#include "c-lang.h"
#include "ada-lang.h"
#include "split-name.h"
#include <algorithm>
@@ -210,14 +211,17 @@ cooked_index::do_finalize ()
m_names.push_back (std::move (canon_name));
}
}
- else if (entry->per_cu->lang () == language_cplus)
+ else if (entry->per_cu->lang () == language_cplus
+ || entry->per_cu->lang () == language_c)
{
void **slot = htab_find_slot (seen_names.get (), entry,
INSERT);
if (*slot == nullptr)
{
gdb::unique_xmalloc_ptr<char> canon_name
- = cp_canonicalize_string (entry->name);
+ = (entry->per_cu->lang () == language_cplus
+ ? cp_canonicalize_string (entry->name)
+ : c_canonicalize_name (entry->name));
if (canon_name == nullptr)
entry->canonical = entry->name;
else
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index aa13d42..032e20a 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -22014,7 +22014,10 @@ static const char *
dwarf2_canonicalize_name (const char *name, struct dwarf2_cu *cu,
struct objfile *objfile)
{
- if (name && cu->lang () == language_cplus)
+ if (name == nullptr)
+ return name;
+
+ if (cu->lang () == language_cplus)
{
gdb::unique_xmalloc_ptr<char> canon_name
= cp_canonicalize_string (name);
@@ -22022,6 +22025,14 @@ dwarf2_canonicalize_name (const char *name, struct dwarf2_cu *cu,
if (canon_name != nullptr)
name = objfile->intern (canon_name.get ());
}
+ else if (cu->lang () == language_c)
+ {
+ gdb::unique_xmalloc_ptr<char> canon_name
+ = c_canonicalize_name (name);
+
+ if (canon_name != nullptr)
+ name = objfile->intern (canon_name.get ());
+ }
return name;
}
@@ -22050,6 +22061,11 @@ dwarf2_name (struct die_info *die, struct dwarf2_cu *cu)
switch (die->tag)
{
+ /* A member's name should not be canonicalized. This is a bit
+ of a hack, in that normally it should not be possible to run
+ into this situation; however, the dw2-unusual-field-names.exp
+ test creates custom DWARF that does. */
+ case DW_TAG_member:
case DW_TAG_compile_unit:
case DW_TAG_partial_unit:
/* Compilation units have a DW_AT_name that is a filename, not
diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
index 5e8a486..2166257 100644
--- a/gdb/gdbtypes.c
+++ b/gdb/gdbtypes.c
@@ -1729,15 +1729,9 @@ lookup_unsigned_typename (const struct language_defn *language,
struct type *
lookup_signed_typename (const struct language_defn *language, const char *name)
{
- struct type *t;
- char *uns = (char *) alloca (strlen (name) + 8);
-
- strcpy (uns, "signed ");
- strcpy (uns + 7, name);
- t = lookup_typename (language, uns, NULL, 1);
- /* If we don't find "signed FOO" just try again with plain "FOO". */
- if (t != NULL)
- return t;
+ /* In C and C++, "char" and "signed char" are distinct types. */
+ if (streq (name, "char"))
+ name = "signed char";
return lookup_typename (language, name, NULL, 0);
}
diff --git a/gdb/stabsread.c b/gdb/stabsread.c
index 6124435..74d0885 100644
--- a/gdb/stabsread.c
+++ b/gdb/stabsread.c
@@ -736,11 +736,13 @@ define_symbol (CORE_ADDR valu, const char *string, int desc, int type,
if (sym->language () == language_cplus)
{
- char *name = (char *) alloca (p - string + 1);
-
- memcpy (name, string, p - string);
- name[p - string] = '\0';
- new_name = cp_canonicalize_string (name);
+ std::string name (string, p - string);
+ new_name = cp_canonicalize_string (name.c_str ());
+ }
+ else if (sym->language () == language_c)
+ {
+ std::string name (string, p - string);
+ new_name = c_canonicalize_name (name.c_str ());
}
if (new_name != nullptr)
sym->compute_and_set_names (new_name.get (), true, objfile->per_bfd);
@@ -1592,12 +1594,18 @@ read_type (const char **pp, struct objfile *objfile)
type_name = NULL;
if (get_current_subfile ()->language == language_cplus)
{
- char *name = (char *) alloca (p - *pp + 1);
-
- memcpy (name, *pp, p - *pp);
- name[p - *pp] = '\0';
-
- gdb::unique_xmalloc_ptr<char> new_name = cp_canonicalize_string (name);
+ std::string name (*pp, p - *pp);
+ gdb::unique_xmalloc_ptr<char> new_name
+ = cp_canonicalize_string (name.c_str ());
+ if (new_name != nullptr)
+ type_name = obstack_strdup (&objfile->objfile_obstack,
+ new_name.get ());
+ }
+ else if (get_current_subfile ()->language == language_c)
+ {
+ std::string name (*pp, p - *pp);
+ gdb::unique_xmalloc_ptr<char> new_name
+ = c_canonicalize_name (name.c_str ());
if (new_name != nullptr)
type_name = obstack_strdup (&objfile->objfile_obstack,
new_name.get ());
diff --git a/gdb/testsuite/gdb.dwarf2/enum-type.exp b/gdb/testsuite/gdb.dwarf2/enum-type.exp
index ed8e3a3..983b415 100644
--- a/gdb/testsuite/gdb.dwarf2/enum-type.exp
+++ b/gdb/testsuite/gdb.dwarf2/enum-type.exp
@@ -37,13 +37,13 @@
integer_label: DW_TAG_base_type {
{DW_AT_byte_size 4 DW_FORM_sdata}
{DW_AT_encoding @DW_ATE_signed}
- {DW_AT_name integer}
+ {DW_AT_name int}
}
uinteger_label: DW_TAG_base_type {
{DW_AT_byte_size 4 DW_FORM_sdata}
{DW_AT_encoding @DW_ATE_unsigned}
- {DW_AT_name {unsigned integer}}
+ {DW_AT_name {unsigned int}}
}
DW_TAG_enumeration_type {
@@ -79,5 +79,5 @@
gdb_test "ptype enum EU" "type = enum EU {TWO = 2}" \
"ptype EU in enum C"
gdb_test_no_output "set lang c++"
-gdb_test "ptype enum EU" "type = enum EU : unsigned integer {TWO = 2}" \
+gdb_test "ptype enum EU" "type = enum EU : unsigned int {TWO = 2}" \
"ptype EU in C++"
