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[commit/Ada] Handle reference to array descriptors
- From: Joel Brobecker <brobecker at adacore dot com>
- To: gdb-patches at sourceware dot org
- Cc: Joel Brobecker <brobecker at adacore dot com>
- Date: Wed, 29 Feb 2012 11:33:33 -0800
- Subject: [commit/Ada] Handle reference to array descriptors
This patch is to help handle aliased array variables, such as:
type Bounded is array (Integer range <>) of Integer;
function New_Bounded (Low, High : Integer) return Bounded;
BT : aliased Bounded := New_Bounded (Low => 1, High => 3);
In that case, the compiler describes variable "BT" as a reference
to a thin pointer, and GDB is unable to print its value:
(gdb) p bt
$1 =
The problems starts when ada_value_print deconstructs the struct
value into contents and address in order to call val_print. It
turns out in this case that "bt" is not an lval. In the debug
information, this variable's location is described as:
.uleb128 0xd # (DIE (0xe0) DW_TAG_variable)
.ascii "bt\0" # DW_AT_name
[...]
.byte 0x6 # DW_AT_location
.byte 0x91 # DW_OP_fbreg
.sleb128 -56
.byte 0x6 # DW_OP_deref
.byte 0x23 # DW_OP_plus_uconst
.uleb128 0x8
.byte 0x9f # DW_OP_stack_value
So, when ada_value_print passes the bt's (value) address, it passes
in effect a meaningless address. The problem continues shortly after
when ada_val_print_1 re-creates the value from the contents and address.
The value has become an lval_memory, with a null address.
As a result, we trigger a memory error later on, while trying to
read the array bounds in order to transform our value into a simple
array.
To avoid the problem entirely, the fix is to coerce references before
transforming array descriptors into simple arrays.
gdb/ChangeLog:
* ada-valprint.c (ada_val_print_1): If our value is a reference
to an array descriptor, dereference it before converting it
to a simple array.
gdb/testsuite/ChangeLog:
* gdb.ada/aliased_array: New testcase.
Tested on x86_64-linux. Checked in.
---
gdb/ChangeLog | 6 ++++
gdb/ada-valprint.c | 4 +++
gdb/testsuite/ChangeLog | 4 +++
gdb/testsuite/gdb.ada/aliased_array.exp | 36 +++++++++++++++++++++++++++
gdb/testsuite/gdb.ada/aliased_array/foo.adb | 22 ++++++++++++++++
gdb/testsuite/gdb.ada/aliased_array/pck.adb | 30 ++++++++++++++++++++++
gdb/testsuite/gdb.ada/aliased_array/pck.ads | 21 +++++++++++++++
7 files changed, 123 insertions(+), 0 deletions(-)
create mode 100644 gdb/testsuite/gdb.ada/aliased_array.exp
create mode 100644 gdb/testsuite/gdb.ada/aliased_array/foo.adb
create mode 100644 gdb/testsuite/gdb.ada/aliased_array/pck.adb
create mode 100644 gdb/testsuite/gdb.ada/aliased_array/pck.ads
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 064efa2..d09ed94 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
2012-02-29 Joel Brobecker <brobecker@adacore.com>
+ * ada-valprint.c (ada_val_print_1): If our value is a reference
+ to an array descriptor, dereference it before converting it
+ to a simple array.
+
+2012-02-29 Joel Brobecker <brobecker@adacore.com>
+
* ada-lang.c (ada_to_fixed_value): Call unwrap_value before
creating fixed value.
(ada_value_ind, ada_coerce_ref, assign_component)
diff --git a/gdb/ada-valprint.c b/gdb/ada-valprint.c
index f43f3e3..5cb2f98 100644
--- a/gdb/ada-valprint.c
+++ b/gdb/ada-valprint.c
@@ -689,6 +689,10 @@ ada_val_print_1 (struct type *type, const gdb_byte *valaddr,
struct value *val;
val = value_from_contents_and_address (type, valaddr + offset, address);
+ /* If this is a reference, coerce it now. This helps taking care
+ of the case where ADDRESS is meaningless because original_value
+ was not an lval. */
+ val = coerce_ref (val);
if (TYPE_CODE (type) == TYPE_CODE_TYPEDEF) /* array access type. */
val = ada_coerce_to_simple_array_ptr (val);
else
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 8a144bc..af77953 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,9 @@
2012-02-29 Joel Brobecker <brobecker@adacore.com>
+ * gdb.ada/aliased_array: New testcase.
+
+2012-02-29 Joel Brobecker <brobecker@adacore.com>
+
* gdb.ada/whatis_array_val: New testcase.
2012-02-29 Jan Kratochvil <jan.kratochvil@redhat.com>
diff --git a/gdb/testsuite/gdb.ada/aliased_array.exp b/gdb/testsuite/gdb.ada/aliased_array.exp
new file mode 100644
index 0000000..9fe30df
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/aliased_array.exp
@@ -0,0 +1,36 @@
+# Copyright 2012 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 "ada.exp"
+
+if { [skip_ada_tests] } { return -1 }
+
+set testdir "aliased_array"
+set testfile "${testdir}/foo"
+set srcfile ${srcdir}/${subdir}/${testfile}.adb
+set binfile ${objdir}/${subdir}/${testfile}
+
+file mkdir ${objdir}/${subdir}/${testdir}
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable {debug}] != ""} {
+ return -1
+}
+
+clean_restart ${testfile}
+
+set bp_location [gdb_get_line_number "STOP" ${testdir}/foo.adb]
+runto "foo.adb:$bp_location"
+
+gdb_test "print bt" " = \\(1, 2, 3\\)"
+
diff --git a/gdb/testsuite/gdb.ada/aliased_array/foo.adb b/gdb/testsuite/gdb.ada/aliased_array/foo.adb
new file mode 100644
index 0000000..28acc87
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/aliased_array/foo.adb
@@ -0,0 +1,22 @@
+-- Copyright 2012 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/>.
+
+with Pck; use Pck;
+procedure Foo is
+ BT : aliased Bounded := New_Bounded (Low => 1, High => 3);
+begin
+ Do_Nothing (BT'Address); -- STOP
+end Foo;
+
diff --git a/gdb/testsuite/gdb.ada/aliased_array/pck.adb b/gdb/testsuite/gdb.ada/aliased_array/pck.adb
new file mode 100644
index 0000000..29de743
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/aliased_array/pck.adb
@@ -0,0 +1,30 @@
+-- Copyright 2012 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/>.
+
+package body Pck is
+ function New_Bounded (Low, High : Integer) return Bounded is
+ Result : Bounded (Low .. High);
+ begin
+ for J in Low .. High loop
+ Result (J) := J;
+ end loop;
+ return Result;
+ end New_Bounded;
+
+ procedure Do_Nothing (A : System.Address) is
+ begin
+ null;
+ end Do_Nothing;
+end Pck;
diff --git a/gdb/testsuite/gdb.ada/aliased_array/pck.ads b/gdb/testsuite/gdb.ada/aliased_array/pck.ads
new file mode 100644
index 0000000..bfff520
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/aliased_array/pck.ads
@@ -0,0 +1,21 @@
+-- Copyright 2012 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/>.
+
+with System;
+package Pck is
+ type Bounded is array (Integer range <>) of Integer;
+ function New_Bounded (Low, High : Integer) return Bounded;
+ procedure Do_Nothing (A : System.Address);
+end Pck;
--
1.7.1