Implement some agent expressions for Ada

Ada historically has not implemented agent expressions, and some Ada
constructs probably cannot reasonably be converted to agent
expressions.  However, a subset of simple operations can be, and this
patch represents a first step in that direction.

On one internal AdaCore test case, this improves the performance of a
conditional breakpoint from 5 minutes to 5 seconds.

The main tricky part in this patch is ensuring the converted
expressions detect the cases that will not work.  This is done by
examining the code in the corresponding evaluation methods.

1 files changed, 20 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.ada/ax-ada/prog.adb b/gdb/testsuite/gdb.ada/ax-ada/prog.adb
new file mode 100644
index 0000000..3852711
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/ax-ada/prog.adb
@@ -0,0 +1,20 @@
+--  Copyright 2023 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/>.
+
+procedure Prog is
+   Variable : Integer := 23;
+begin
+   null; -- START
+end Prog;