[RFA/Ada] Breakpoints on task bodies

[Joel Brobecker <brobecker at adacore dot com>]

Hello,

This is something that Tom and I discussed on IRC.

Consider the following declaration:

    package Pck is
       task Dummy_Task is
          entry Start;
       end Dummy_Task;
    end Pck;

Inserting a breakpoint on the body of that task does not currently
work:

    (gdb) b pck.dummy_task
    "pck.dummy_task" is not a function
    Make breakpoint pending on future shared library load? (y or [n]) n

What happens here is that the compiler generates two symbols:

  (a) Symbol `pck__dummy_task' which is a *variable* referencing
      the task;

  (b) Symbol `pck__dummy_taskTKB' which is the subprogram implementing
      the body of the task.

The symbol lookup only finds the variable before of the TKB suffix in
the subprogram name. This patch fixes the problem by adjusting the
ada-lang.c:is_name_suffix routine to recognize "TKB" suffixes.  But
that's not enough, because the search in the symtab is performed via
the block dictionary, using a hashing algorithm. So, for the search
to find `pck__dummy_taskTKB', I had to modify the hashing function
to ignore TKB suffixes as well.

gdb/ChangeLog:

        * ada-lang.c (is_name_suffix): Add handling of "TKB" suffixes.
        Update function documentation.
        * dictionary.c (dict_hash): Ignore "TKB" suffixes in hash
        computation.

gdb/testsuite/ChangeLog:

        * gdb.ada/task_bp: New testcase.

Tested on x86_64-linux, no regression.
OK to commit?

---
 gdb/ada-lang.c                        |    6 +++
 gdb/dictionary.c                      |   11 +++++
 gdb/testsuite/gdb.ada/task_bp.exp     |   68 +++++++++++++++++++++++++++++++++
 gdb/testsuite/gdb.ada/task_bp/foo.adb |   20 ++++++++++
 gdb/testsuite/gdb.ada/task_bp/pck.adb |   21 ++++++++++
 gdb/testsuite/gdb.ada/task_bp/pck.ads |   20 ++++++++++
 6 files changed, 146 insertions(+), 0 deletions(-)
 create mode 100644 gdb/testsuite/gdb.ada/task_bp.exp
 create mode 100644 gdb/testsuite/gdb.ada/task_bp/foo.adb
 create mode 100644 gdb/testsuite/gdb.ada/task_bp/pck.adb
 create mode 100644 gdb/testsuite/gdb.ada/task_bp/pck.ads

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 1ee16a3..5829f6c 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -5106,6 +5106,7 @@ ada_lookup_symbol_nonlocal (const char *name,
 
    [.$][0-9]+       [nested subprogram suffix, on platforms such as GNU/Linux]
    ___[0-9]+        [nested subprogram suffix, on platforms such as HP/UX]
+   TKB              [subprogram suffix for task bodies]
    _E[0-9]+[bs]$    [protected object entry suffixes]
    (X[nb]*)?((\$|__)[0-9](_?[0-9]+)|___(JM|LJM|X([FDBUP].*|R[^T]?)))?$
 
@@ -5151,6 +5152,11 @@ is_name_suffix (const char *str)
         return 1;
     }
 
+  /* "TKB" suffixes are used for subprograms implementing task bodies.  */
+
+  if (strcmp (str, "TKB") == 0)
+    return 1;
+
 #if 0
   /* FIXME: brobecker/2005-09-23: Protected Object subprograms end
      with a N at the end.  Unfortunately, the compiler uses the same
diff --git a/gdb/dictionary.c b/gdb/dictionary.c
index 8142d29..7c451d2 100644
--- a/gdb/dictionary.c
+++ b/gdb/dictionary.c
@@ -801,6 +801,17 @@ dict_hash (const char *string0)
   hash = 0;
   while (*string)
     {
+      /* Ignore "TKB" suffixes.
+
+	 These are used by Ada for subprograms implementing a task body.
+	 For instance for a task T inside package Pck, the name of the
+	 subprogram implementing T's body is `pck__tTKB'.  We need to
+	 ignore the "TKB" suffix because searches for this task body
+	 subprogram are going to be performed using `pck__t' (the encoded
+	 version of the natural name `pck.t').  */
+      if (strcmp (string, "TKB") == 0)
+	return hash;
+
       switch (*string)
 	{
 	case '$':
diff --git a/gdb/testsuite/gdb.ada/task_bp.exp b/gdb/testsuite/gdb.ada/task_bp.exp
new file mode 100644
index 0000000..3d07ad6
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/task_bp.exp
@@ -0,0 +1,68 @@
+# Copyright 2011 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+load_lib "ada.exp"
+
+set testdir "task_bp"
+set testfile "${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 [list debug]] != "" } {
+  return -1
+}
+
+# Insert a breakpoint at LOC, and run the program expecting us to
+# reach that breakpoint.
+#
+# LOC is expected to be a linespec referencing the body of task
+# Pck.Dummy_Task (the purpose is to test all the variations of
+# these equivalent linespecs).
+#
+# MSG is just a string that's used to qualify the name of the tests
+# that are executed inside that procedure.  The purpose to be able
+# to call that function multiple times with the same linespec, in
+# order to test one given linespec under multiple conditions.
+
+proc test_bp { loc msg } {
+   gdb_test "break $loc" \
+     "Breakpoint \[0-9\]+ at 0x\[0-9a-fA-F\]+: file .*pck.adb, line \[0-9\]+\." \
+     "break $loc - $msg"
+
+   gdb_run_cmd
+   gdb_test "" \
+     "Breakpoint \[0-9\]+, pck\\.dummy_task (.*)" \
+     "run to $loc - $msg"
+}
+
+set all_linespecs { "pck.dummy_task" "dummy_task"
+                    "pck.adb:pck.dummy_task" "pck.adb:dummy_task"}
+
+# First, test the linespecs when the associated symtab hasn't been
+# expanded yet.
+
+foreach linespec $all_linespecs {
+    clean_restart ${testfile}
+    test_bp $linespec "from psymtab"
+}
+
+# Now, do the same, but with the associated symtab already expanded.
+
+foreach linespec $all_linespecs {
+    clean_restart ${testfile}
+    gdb_test "list pck.adb:1" ".*" "expanding symtab for $linespec"
+    test_bp $linespec "from full symtab"
+}
diff --git a/gdb/testsuite/gdb.ada/task_bp/foo.adb b/gdb/testsuite/gdb.ada/task_bp/foo.adb
new file mode 100644
index 0000000..98919a9
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/task_bp/foo.adb
@@ -0,0 +1,20 @@
+--  Copyright 2011 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
+begin
+   Dummy_Task.Start;
+end Foo;
diff --git a/gdb/testsuite/gdb.ada/task_bp/pck.adb b/gdb/testsuite/gdb.ada/task_bp/pck.adb
new file mode 100644
index 0000000..0b1a15c
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/task_bp/pck.adb
@@ -0,0 +1,21 @@
+--  Copyright 2011 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
+   task body Dummy_Task is
+   begin
+      accept Start;
+   end Dummy_Task;
+end Pck;
diff --git a/gdb/testsuite/gdb.ada/task_bp/pck.ads b/gdb/testsuite/gdb.ada/task_bp/pck.ads
new file mode 100644
index 0000000..37460ed
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/task_bp/pck.ads
@@ -0,0 +1,20 @@
+--  Copyright 2011 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 Pck is
+   task Dummy_Task is
+      entry Start;
+   end Dummy_Task;
+end Pck;
-- 
1.7.1