* breakpoint.c (fetch_watchpoint_value): New function.

	(update_watchpoint): Set and clear val_valid.  Use
	fetch_watchpoint_value.  Handle unreadable values on the
	value chain.  Correct check for user-requested array watchpoints.
	(breakpoint_init_inferior): Clear val_valid.
	(watchpoint_value_print): New function.
	(print_it_typical): Use it.  Do not free or clear old_val.  Print
	watchpoints even if old_val == NULL.
	(watchpoint_check): Use fetch_watchpoint_value.  Check for values
	becoming readable or unreadable.
	(watch_command_1): Use fetch_watchpoint_value.  Set val_valid.
	(do_enable_watchpoint): Likewise.
	* breakpoint.h (struct breakpoint): Update comment for val.  Add
	val_valid.
	* NEWS: Mention watchpoints on inaccessible memory.

	* gdb.base/watchpoint.c (global_ptr, func4): New.
	(main): Call func4.
	* gdb.base/watchpoint.exp: Call test_inaccessible_watchpoint.
	(test_inaccessible_watchpoint): New.

	* gdb.texinfo (Set Watchpoints): Mention watchpoints on
	unreadable memory.  Delete obsolete SPARClite reference.

2 files changed, 15 insertions, 11 deletions

diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 95d94d9..6e68899 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,8 @@
+2008-03-03  Daniel Jacobowitz  <dan@codesourcery.com>
+
+	* gdb.texinfo (Set Watchpoints): Mention watchpoints on
+	unreadable memory.  Delete obsolete SPARClite reference.
+
 2008-02-28  Daniel Jacobowitz  <dan@codesourcery.com>
 
 	* gdb.texinfo (Starting): Mention always-running targets.
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index dfc6e81..1a0e9d2 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -3211,6 +3211,16 @@ expression can use any operators valid in the program's native
 language (@pxref{Languages}).
 @end itemize
 
+You can set a watchpoint on an expression even if the expression can
+not be evaluated yet.  For instance, you can set a watchpoint on
+@samp{*global_ptr} before @samp{global_ptr} is initialized.
+@value{GDBN} will stop when your program sets @samp{global_ptr} and
+the expression produces a valid value.  If the expression becomes
+valid in some other way than changing a variable (e.g.@: if the memory
+pointed to by @samp{*global_ptr} becomes readable as the result of a
+@code{malloc} call), @value{GDBN} may not stop until the next time
+the expression changes.
+
 @cindex software watchpoints
 @cindex hardware watchpoints
 Depending on your system, watchpoints may be implemented in software or
@@ -3338,17 +3348,6 @@ exhaust the resources available for hardware-assisted watchpoints.
 That's because @value{GDBN} needs to watch every variable in the
 expression with separately allocated resources.
 
-The SPARClite DSU will generate traps when a program accesses some data
-or instruction address that is assigned to the debug registers.  For the
-data addresses, DSU facilitates the @code{watch} command.  However the
-hardware breakpoint registers can only take two data watchpoints, and
-both watchpoints must be the same kind.  For example, you can set two
-watchpoints with @code{watch} commands, two with @code{rwatch} commands,
-@strong{or} two with @code{awatch} commands, but you cannot set one
-watchpoint with one command and the other with a different command.
-@value{GDBN} will reject the command if you try to mix watchpoints.
-Delete or disable unused watchpoint commands before setting new ones.
-
 If you call a function interactively using @code{print} or @code{call},
 any watchpoints you have set will be inactive until @value{GDBN} reaches another
 kind of breakpoint or the call completes.