handle DW_AT_type on an enumeration
Commit Message
DWARF allows an enumeration type to have a DW_AT_type. GDB doesn't
recognize this, but there is a patch to change GCC to emit it, and a
DWARF proposal to further allow an enum type with a DW_AT_type to omit
the DW_AT_byte_size. This patch changes gdb to implement this.
Built and regtested on x86-64 Fedora 20.
2014-03-27 Tom Tromey <tromey@redhat.com>
* dwarf2read.c (read_enumeration_type): Handle DW_AT_type.
2014-03-27 Tom Tromey <tromey@redhat.com>
* gdb.dwarf2/enum-type.exp: New file.
---
gdb/ChangeLog | 4 +++
gdb/dwarf2read.c | 22 +++++++++++++
gdb/testsuite/ChangeLog | 4 +++
gdb/testsuite/gdb.dwarf2/enum-type.exp | 60 ++++++++++++++++++++++++++++++++++
4 files changed, 90 insertions(+)
create mode 100644 gdb/testsuite/gdb.dwarf2/enum-type.exp
Comments
On Thu, 2014-03-27 at 10:14 -0600, Tom Tromey wrote:
> DWARF allows an enumeration type to have a DW_AT_type. GDB doesn't
> recognize this, but there is a patch to change GCC to emit it, and a
> DWARF proposal to further allow an enum type with a DW_AT_type to omit
> the DW_AT_byte_size. This patch changes gdb to implement this.
Note that neither the gcc patch nor the DWARF spec clarification have
been accepted yet. But I do think consensus is that this is the proper
way to do things.
> Built and regtested on x86-64 Fedora 20.
I build and did a make check against GCC with this patch applied:
http://gcc.gnu.org/ml/gcc-patches/2014-03/msg01448.html
And saw no regressions (and the new test passes) on RHEL6 x86_64.
> @@ -13247,6 +13255,20 @@ read_enumeration_type (struct die_info *die, struct dwarf2_cu *cu)
> /* Finish the creation of this type by using the enum's children. */
> update_enumeration_type_from_children (die, type, cu);
You might want to add a comment here that you are still calling
update_enumeration_type_from_children to guess the TYPE_FLAG_ENUM even
though you will drop the TYPE_UNSIGNED guess later. At least I was a
little confused at first why you still called
update_enumeration_type_from_children in case you already knew the type.
Cheers,
Mark
@@ -13226,6 +13226,14 @@ read_enumeration_type (struct die_info *die, struct dwarf2_cu *cu)
if (name != NULL)
TYPE_TAG_NAME (type) = name;
+ attr = dwarf2_attr (die, DW_AT_type, cu);
+ if (attr != NULL)
+ {
+ struct type *underlying_type = die_type (die, cu);
+
+ TYPE_TARGET_TYPE (type) = underlying_type;
+ }
+
attr = dwarf2_attr (die, DW_AT_byte_size, cu);
if (attr)
{
@@ -13247,6 +13255,20 @@ read_enumeration_type (struct die_info *die, struct dwarf2_cu *cu)
/* Finish the creation of this type by using the enum's children. */
update_enumeration_type_from_children (die, type, cu);
+ /* If this type has an underlying type that is not a stub, then we
+ may use its attributes. We always use the "unsigned" attribute
+ in this situation, because ordinarily we guess whether the type
+ is unsigned -- but the guess can be wrong and the underlying type
+ can tell us the reality. However, we defer to a local size
+ attribute if one exists, because this lets the compiler override
+ the underlying type if needed. */
+ if (TYPE_TARGET_TYPE (type) != NULL && !TYPE_STUB (TYPE_TARGET_TYPE (type)))
+ {
+ TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TYPE_TARGET_TYPE (type));
+ if (TYPE_LENGTH (type) == 0)
+ TYPE_LENGTH (type) = TYPE_LENGTH (TYPE_TARGET_TYPE (type));
+ }
+
return set_die_type (die, type, cu);
}
new file mode 100644
@@ -0,0 +1,60 @@
+# Copyright 2014 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.c enum-type-dw.S
+
+# Make some DWARF for the test.
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+ cu {} {
+ DW_TAG_compile_unit {
+ {DW_AT_language @DW_LANG_C}
+ {DW_AT_name enum-type-dw.c}
+ {DW_AT_comp_dir /tmp}
+ } {
+ declare_labels integer_label array_elt_label array_label \
+ big_array_label
+
+ integer_label: DW_TAG_base_type {
+ {DW_AT_byte_size 4 DW_FORM_sdata}
+ {DW_AT_encoding @DW_ATE_signed}
+ {DW_AT_name integer}
+ }
+
+ DW_TAG_enumeration_type {
+ {DW_AT_name E}
+ {DW_AT_type :$integer_label}
+ } {
+ DW_TAG_enumerator {
+ {DW_AT_name ONE}
+ {DW_AT_const_value 1}
+ }
+ }
+ }
+ }
+}
+
+if { [prepare_for_testing ${testfile}.exp ${testfile} \
+ [list $srcfile $asm_file] {nodebug}] } {
+ return -1
+}
+
+gdb_test "print sizeof(enum E)" " = 4"