Re: Your change to can_use_hardware_watchpoint breaks hw wp

[Eli Zaretskii <eliz@gnu.org>]

> Could you please tell me what bug your patch tried to fix?

It fixes two problems:

 - the previous code used a macro that only looked at the watched
   region's size, whereas some platforms, like x86, need to know the
   address itself as well, because the alignment of the address is
   important in order to compute how many debug registers are
   required to watch the region.  Hence the new macro,
   TARGET_REGION_OK_FOR_HW_WATCHPOINT.

 - the other problem, which I'm guessing is the one that caused you
   grief, is that the old code would simply ignore values on the value
   chain that were not in memory, when checking whether the expression
   can be watched with hardware watchpoints.  By contrast, when the
   time came to actually insert the watchpoints, any value that is not
   in memory would cause GDB to fail to insert the watchpoint.  The
   change made GDB's behavior consistent, in that it would not even
   try hardware watchpoints if some value on the value chain is not in
   memory.

The latter issue was discussed on this list under the subject "Code in
can_use_hardware_watchpoint()" starting on 15 Aug.  The conclusion was
that the change was a Good Thing.