x86 debug address register clarifications

The loop macro ALL_DEBUG_REGISTERS does not iterate over the status or
control registers, so its name is misleading.  This commit renames it
as ALL_DEBUG_ADDRESS_REGISTERS and updates all uses.  This commit also
updates its loop conditions to an equivalent but better form, and
makes two functions use it that had previously hardwired the loop.
A comment on a related field in the x86_debug_reg_state structure is
also updated to reflect that the field refers specifically to address
registers only.

gdb/ChangeLog:

	* nat/x86-dregs.h (ALL_DEBUG_REGISTERS): Renamed as...
	(ALL_DEBUG_ADDRESS_REGISTERS): New macro.  All uses updated.
	Loop conditions	changed to equivalent form.
	(struct x86_debug_reg_state): Updated dr_ref_count comment.
	* x86-linux-nat.c (x86_linux_prepare_to_resume): Use
	ALL_DEBUG_ADDRESS_REGISTERS.

gdb/gdbserver/ChangeLog:

	* linux-x86-low.c (x86_linux_prepare_to_resume): Use
	ALL_DEBUG_ADDRESS_REGISTERS.

1 files changed, 4 insertions, 3 deletions

diff --git a/gdb/nat/x86-dregs.h b/gdb/nat/x86-dregs.h
index fb179a5..aebcbce 100644
--- a/gdb/nat/x86-dregs.h
+++ b/gdb/nat/x86-dregs.h
@@ -85,12 +85,13 @@ struct x86_debug_reg_state
   CORE_ADDR dr_mirror[DR_NADDR];
   unsigned dr_status_mirror, dr_control_mirror;
 
-  /* Reference counts for each debug register.  */
+  /* Reference counts for each debug address register.  */
   int dr_ref_count[DR_NADDR];
 };
 
-/* A macro to loop over all debug registers.  */
-#define ALL_DEBUG_REGISTERS(i)	for (i = 0; i < DR_NADDR; i++)
+/* A macro to loop over all debug address registers.  */
+#define ALL_DEBUG_ADDRESS_REGISTERS(i) \
+  for (i = DR_FIRSTADDR; i <= DR_LASTADDR; i++)
 
 /* Insert a watchpoint to watch a memory region which starts at
    address ADDR and whose length is LEN bytes.  Watch memory accesses