[patch] Fix for PR gdb/11022

[ppluzhnikov@google.com (Paul Pluzhnikov)]

Greetings,

This patch requires my earlier observer patch:
  http://sourceware.org/ml/gdb-patches/2009-11/msg00563.html
fixes PR gdb/11022 and adds a test case for it.

Thanks,
--
Paul Pluzhnikov

gdb/ChangeLog:

2009-11-25  Paul Pluzhnikov  <ppluzhnikov@google.com>

	PR gdb/11022

	* breakpoint.c (invalidate_bp_value_on_memory_change):
	New function.
	(_initialize_breakpoint): Add it as memory change observer.


gdb/testsuite/ChangeLog:

2009-11-25  Paul Pluzhnikov  <ppluzhnikov@google.com>

	PR gdb/11022

	* gdb.base/pr11022.exp: New test.
	* gdb.base/pr11022.c: New test.

Index: breakpoint.c
===================================================================
RCS file: /cvs/src/src/gdb/breakpoint.c,v
retrieving revision 1.436
diff -u -p -u -r1.436 breakpoint.c
--- breakpoint.c	24 Nov 2009 21:37:52 -0000	1.436
+++ breakpoint.c	25 Nov 2009 23:34:39 -0000
@@ -9490,6 +9490,35 @@ show_breakpoint_cmd (char *args, int fro
 {
 }
 
+/* Invalidate last known value of any hardware watchpoint if
+   the memory which that value represents has been written to by
+   GDB itself.  */
+
+static void
+invalidate_bp_value_on_memory_change (CORE_ADDR addr, int len,
+				      const bfd_byte *data)
+{
+  struct breakpoint *bp;
+
+  ALL_BREAKPOINTS (bp)
+    if (bp->enable_state == bp_enabled
+	&& bp->type == bp_hardware_watchpoint
+	&& bp->val_valid && bp->val)
+      {
+	struct bp_location *loc;
+
+	for (loc = bp->loc; loc != NULL; loc = loc->next)
+	  if (loc->loc_type == bp_loc_hardware_watchpoint
+	      && loc->address + loc->length > addr
+	      && addr + len > loc->address)
+	    {
+	      value_free (bp->val);
+	      bp->val = NULL;
+	      bp->val_valid = 0;
+	    }
+      }
+}
+
 /* Use default_breakpoint_'s, or nothing if they aren't valid.  */
 
 struct symtabs_and_lines
@@ -10077,6 +10106,7 @@ _initialize_breakpoint (void)
 
   observer_attach_solib_unloaded (disable_breakpoints_in_unloaded_shlib);
   observer_attach_inferior_exit (clear_syscall_counts);
+  observer_attach_memory_changed (invalidate_bp_value_on_memory_change);
 
   breakpoint_chain = 0;
   /* Don't bother to call set_breakpoint_count.  $bpnum isn't useful
Index: testsuite/gdb.base/pr11022.c
===================================================================
RCS file: testsuite/gdb.base/pr11022.c
diff -N testsuite/gdb.base/pr11022.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/pr11022.c	25 Nov 2009 23:34:39 -0000
@@ -0,0 +1,32 @@
+/* This test is part of GDB, the GNU debugger.
+
+   Copyright 2009 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/>.
+   */
+
+int x;
+
+int
+main ()
+{
+  int i, j;
+
+  for (i = 0; i < 500; ++i) {
+    j = 0;  // break here
+    x = 42;
+    j = i;  // expect HW watchpoint stop
+  }
+  return 0;
+}
Index: testsuite/gdb.base/pr11022.exp
===================================================================
RCS file: testsuite/gdb.base/pr11022.exp
diff -N testsuite/gdb.base/pr11022.exp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/pr11022.exp	25 Nov 2009 23:34:39 -0000
@@ -0,0 +1,58 @@
+# Copyright 2009
+# 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/>.
+
+if $tracelevel then {
+    strace $tracelevel
+}
+
+if [target_info exists gdb,no_hardware_watchpoints] {
+    # This test requires HW watchpoints
+    untested pr11022.exp
+    return -1
+}
+
+set testfile "pr11022"
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+     untested pr11022.exp
+     return -1
+}
+
+# Start with a fresh gdb.
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+if ![runto_main] then {
+    fail "Can't run to main"
+    return 0
+}
+
+gdb_test "break [gdb_get_line_number "break here"]" \
+	".*Breakpoint.* at .*" \
+	"set breakpoint"
+
+gdb_test "watch x" ".*Hardware watchpoint.*" "set watchpoint"
+gdb_test "continue" ".*break here.*" "breakpoint hit"
+gdb_test "continue" ".*Hardware watchpoint.*Old value = 0.*New value = 42.*" \
+    "watchpoint hit"
+gdb_test "continue" ".*break here.*" "breakpoint hit 2"
+gdb_test "set var x = 1"
+gdb_test "continue" ".*Hardware watchpoint.*Old value = 1.*New value = 42.*" \
+    "watchpoint hit 2"