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* [binutils-gdb] [gdb/symtab] Handle struct decl with DW_AT_signature
@ 2020-04-28 4:12 Tom de Vries
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From: Tom de Vries @ 2020-04-28 4:12 UTC (permalink / raw)
To: gdb-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=15cd93d05e8e84644acc8bbeaa3d5f4280cc5159
commit 15cd93d05e8e84644acc8bbeaa3d5f4280cc5159
Author: Tom de Vries <tdevries@suse.de>
Date: Tue Apr 28 06:12:35 2020 +0200
[gdb/symtab] Handle struct decl with DW_AT_signature
Consider a test-case with sources 36.c:
...
struct s { int i; };
extern void f (void);
int main (void) {
struct s a;
f ();
return 0;
}
...
and 36b.c:
...
struct s { int j; };
void f (void) {
struct s b;
}
...
compiled like this:
...
$ gcc 36.c 36b.c -g
...
It contains DWARF like this:
...
<0><d2>: Abbrev Number: 1 (DW_TAG_compile_unit)
<d8> DW_AT_name : 36.c
<1><f4>: Abbrev Number: 2 (DW_TAG_structure_type)
<f5> DW_AT_name : s
<2><fe>: Abbrev Number: 3 (DW_TAG_member)
<ff> DW_AT_name : i
<1><110>: Abbrev Number: 5 (DW_TAG_subprogram)
<111> DW_AT_name : main
<2><12d>: Abbrev Number: 6 (DW_TAG_variable)
<12e> DW_AT_name : a
<132> DW_AT_type : <0xf4>
<0><146>: Abbrev Number: 1 (DW_TAG_compile_unit)
<14c> DW_AT_name : 36b.c
<1><168>: Abbrev Number: 2 (DW_TAG_structure_type)
<169> DW_AT_name : s
<2><172>: Abbrev Number: 3 (DW_TAG_member)
<173> DW_AT_name : j
<1><184>: Abbrev Number: 5 (DW_TAG_subprogram)
<185> DW_AT_name : f
<2><19b>: Abbrev Number: 6 (DW_TAG_variable)
<19c> DW_AT_name : b
<1a0> DW_AT_type : <0x168>
...
And when printing "struct s", we get first a random one (with int j), and then
context-specific ones (with int i in main, and int j in f):
...
$ gdb -batch a.out \
-ex "ptype struct s" \
-ex start \
-ex "ptype struct s" \
-ex "break f" -ex continue \
-ex "ptype struct s" \
| grep "int [ij];"
int j;
int i;
int j;
...
Same for -readnow.
However, if we use -fdebug-types-section:
...
$ gcc 36.c 36b.c -g -fdebug-types-section
...
we get:
...
$ gdb ... | grep "int [ij];"
int j;
int i;
int i;
$ gdb -readnow ... | grep "int [ij];"
int j;
int j;
int j;
...
This is due to the fact that both "struct s" DIEs have been moved to the
.debug_types section:
...
Compilation Unit @ offset 0x0:
Signature: 0xfd1462823bb6f7b7
<0><17>: Abbrev Number: 1 (DW_TAG_type_unit)
<1><1d>: Abbrev Number: 2 (DW_TAG_structure_type)
<1e> DW_AT_name : s
<2><27>: Abbrev Number: 3 (DW_TAG_member)
<28> DW_AT_name : i
Compilation Unit @ offset 0x3a:
Signature: 0x534310fbefba324d
<0><51>: Abbrev Number: 1 (DW_TAG_type_unit)
<1><57>: Abbrev Number: 2 (DW_TAG_structure_type)
<58> DW_AT_name : s
<2><61>: Abbrev Number: 3 (DW_TAG_member)
<62> DW_AT_name : j
...
and there's no longer a "struct s" DIE in the 36.c and
and 36b.c CUs to specify which "struct s" belongs in the CU. This is gcc
PR90232.
However, using a tentative patch for gcc that adds these DIEs (according to
DWARF standard: If the complete declaration of a type has been placed in a
separate type unit, an incomplete declaration of that type in the compilation
unit may provide the unique 64-bit signature of the type using a
DW_AT_signature attribute):
...
<0><d2>: Abbrev Number: 5 (DW_TAG_compile_unit)
<d8> DW_AT_name : 36.c
+ <1><f4>: Abbrev Number: 6 (DW_TAG_structure_type)
+ <f5> DW_AT_name : s
+ <f7> DW_AT_signature : signature: 0xfd1462823bb6f7b7
+ <ff> DW_AT_declaration : 1
<0><13c>: Abbrev Number: 5 (DW_TAG_compile_unit)
<142> DW_AT_name : 36b.c
+ <1><15e>: Abbrev Number: 6 (DW_TAG_structure_type)
+ <15f> DW_AT_name : s
+ <161> DW_AT_signature : signature: 0x534310fbefba324d
+ <169> DW_AT_declaration : 1
...
still does not help, because they're declarations, so new_symbol is not called
for them in process_structure_scope.
Fix this by calling new_symbol for these decls.
Build and tested on x86_64-linux.
Also tested with target board enabling by default -fdebug-types-section
-gdwarf-4, and with gcc with aforementioned tentative patch. In this
configuration, the patch reduces number of FAILs from 2888 to 238.
gdb/ChangeLog:
2020-04-28 Tom de Vries <tdevries@suse.de>
* dwarf2/read.c (process_structure_scope): Add symbol for struct decl
with DW_AT_signature.
gdb/testsuite/ChangeLog:
2020-04-28 Tom de Vries <tdevries@suse.de>
* gdb.dwarf2/main-foo.c: New test.
* gdb.dwarf2/struct-with-sig.exp: New file.
Diff:
---
gdb/ChangeLog | 5 +
gdb/dwarf2/read.c | 3 +-
gdb/testsuite/ChangeLog | 5 +
gdb/testsuite/gdb.dwarf2/main-foo.c | 34 +++++++
gdb/testsuite/gdb.dwarf2/struct-with-sig.exp | 141 +++++++++++++++++++++++++++
5 files changed, 187 insertions(+), 1 deletion(-)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 78b3ed80244..76f6cf78961 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-28 Tom de Vries <tdevries@suse.de>
+
+ * dwarf2/read.c (process_structure_scope): Add symbol for struct decl
+ with DW_AT_signature.
+
2020-04-27 Simon Marchi <simon.marchi@efficios.com>
* configure.ac: Remove check for fs_base/gs_base in
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 976261372bc..82564edd7b2 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -15748,7 +15748,8 @@ process_structure_scope (struct die_info *die, struct dwarf2_cu *cu)
these DIEs are identified by the fact that they have no byte_size
attribute, and a declaration attribute. */
if (dwarf2_attr (die, DW_AT_byte_size, cu) != NULL
- || !die_is_declaration (die, cu))
+ || !die_is_declaration (die, cu)
+ || dwarf2_attr (die, DW_AT_signature, cu) != NULL)
{
struct symbol *sym = new_symbol (die, type, cu);
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 366ecc29edc..2fef7c587ee 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-28 Tom de Vries <tdevries@suse.de>
+
+ * gdb.dwarf2/main-foo.c: New test.
+ * gdb.dwarf2/struct-with-sig.exp: New file.
+
2020-04-25 Tom de Vries <tdevries@suse.de>
* boards/debug-types.exp: New file.
diff --git a/gdb/testsuite/gdb.dwarf2/main-foo.c b/gdb/testsuite/gdb.dwarf2/main-foo.c
new file mode 100644
index 00000000000..82d7b1f40ed
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/main-foo.c
@@ -0,0 +1,34 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2020 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+/* Dummy foo function. */
+
+void
+foo (void)
+{
+ asm ("foo_label: .globl foo_label");
+}
+
+/* Dummy main function. */
+
+int
+main()
+{
+ asm ("main_label: .globl main_label");
+ foo ();
+ return 0;
+}
diff --git a/gdb/testsuite/gdb.dwarf2/struct-with-sig.exp b/gdb/testsuite/gdb.dwarf2/struct-with-sig.exp
new file mode 100644
index 00000000000..1ce013dfea6
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/struct-with-sig.exp
@@ -0,0 +1,141 @@
+# Copyright 2020 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+ return 0
+}
+
+standard_testfile main-foo.c .S
+
+# Make some DWARF for the test.
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+ global srcdir subdir srcfile
+
+ lassign [function_range main ${srcdir}/${subdir}/${srcfile}] \
+ main_start main_length
+
+ lassign [function_range foo ${srcdir}/${subdir}/${srcfile}] \
+ foo_start foo_length
+
+ cu {} {
+ compile_unit {
+ {DW_AT_language @DW_LANG_C}
+ {DW_AT_name main.c}
+ } {
+ structure_type {
+ {name s}
+ {signature 0x0000000000000001 ref_sig8}
+ {declaration 1 flag}
+ }
+ DW_TAG_subprogram {
+ {name "main"}
+ {low_pc $main_start addr}
+ {high_pc "$main_start + $main_length" addr}
+ }
+ }
+ }
+
+ cu {} {
+ compile_unit {
+ {DW_AT_language @DW_LANG_C}
+ {DW_AT_name foo.c}
+ } {
+ structure_type {
+ {name s}
+ {signature 0x0000000000000002 ref_sig8}
+ {declaration 1 flag}
+ }
+ DW_TAG_subprogram {
+ {name "foo"}
+ {low_pc $foo_start addr}
+ {high_pc "$foo_start + $foo_length" addr}
+ }
+ }
+ }
+
+ tu {} 0x0000000000000001 the_type_i {
+ type_unit {} {
+ declare_labels int_type
+
+ the_type_i: structure_type {
+ {name s}
+ {byte_size 4 sdata}
+ } {
+ member {
+ {name i}
+ {type :$int_type}
+ }
+ }
+ int_type: base_type {
+ {name int}
+ {encoding @DW_ATE_signed}
+ {byte_size 4 sdata}
+ }
+ }
+ }
+
+ tu {} 0x0000000000000002 the_type_j {
+ type_unit {} {
+ declare_labels int_type
+
+ the_type_j: structure_type {
+ {name s}
+ {byte_size 4 sdata}
+ } {
+ member {
+ {name j}
+ {type :$int_type}
+ }
+ }
+ int_type: base_type {
+ {name int}
+ {encoding @DW_ATE_signed}
+ {byte_size 4 sdata}
+ }
+ }
+ }
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} \
+ [list $srcfile $asm_file] {nodebug}] } {
+ return -1
+}
+
+set struct_s_i_re \
+ [multi_line \
+ "type = struct s {" \
+ " int i;" \
+ "}"]
+set struct_s_j_re \
+ [multi_line \
+ "type = struct s {" \
+ " int j;" \
+ "}"]
+
+if ![runto_main] {
+ return -1
+}
+
+gdb_test "ptype struct s" $struct_s_i_re \
+ "struct s with int i"
+
+gdb_breakpoint "foo"
+gdb_continue_to_breakpoint "foo"
+
+gdb_test "ptype struct s" $struct_s_j_re \
+ "struct s with int j"
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