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15cd93d05e
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.
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README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.