Vectorize gdbserver x86 debug register accessors

This commit makes gdbserver access the x86 debug register accessor
functions via the same function vector as GDB proper.  This removes
a chunk of conditional code that was previously in i386-{nat,low}.h
and leaves a single macro as the only GDB/gdbserver difference in
nat/i386-dregs.c.

gdb/
2014-06-20  Gary Benson  <gbenson@redhat.com>

	* i386-nat.h (debug_hw_points): Moved to nat/i386-dregs.c.
	(i386_dr_low_type): Moved to nat/i386-dregs.h.
	(i386_dr_low): Likewise.
	(i386_dr_low_can_set_addr): Moved to nat/i386-dregs.c.
	(i386_dr_low_set_addr): Likewise.
	(i386_dr_low_get_addr): Likewise.
	(i386_dr_low_can_set_control): Likewise.
	(i386_dr_low_set_control): Likewise.
	(i386_dr_low_get_control): Likewise.
	(i386_dr_low_get_status): Likewise.
	(i386_get_debug_register_length): Likewise.
	* nat/i386-dregs.h (i386_dr_low_type): Moved from i386-nat.h.
	(i386_dr_low): Likewise.
	* nat/i386-dregs.c (i386-low.h): Remove include.
	(i386-nat.h): Likewise.
	(nat/i386-dregs.h): New include.
	(i386_dr_low_can_set_addr): Moved from i386-nat.h.
	(i386_dr_low_set_addr): Likewise.
	(i386_dr_low_get_addr): Likewise.
	(i386_dr_low_can_set_control): Likewise.
	(i386_dr_low_set_control): Likewise.
	(i386_dr_low_get_control): Likewise.
	(i386_dr_low_get_status): Likewise.
	(i386_get_debug_register_length): Likewise.
	(debug_hw_points): Likewise.

gdb/gdbserver/
2014-06-20  Gary Benson  <gbenson@redhat.com>

	* i386-low.h (i386_dr_low_can_set_addr): Removed.
	(i386_dr_low_set_addr): Likewise.
	(i386_dr_low_get_addr): Likewise.
	(i386_dr_low_can_set_control): Likewise.
	(i386_dr_low_set_control): Likewise.
	(i386_dr_low_get_control): Likewise.
	(i386_dr_low_get_status): Likewise.
	(i386_get_debug_register_length): Likewise.
	* linux-x86-low.c (i386_dr_low_set_addr):
	Changed signature.  Made static.
	(i386_dr_low_get_addr): Likewise.
	(i386_dr_low_set_control): Likewise.
	(i386_dr_low_get_control): Likewise.
	(i386_dr_low_get_status): Likewise.
	(i386_dr_low): New global variable.
	* win32-i386-low.c (i386_dr_low_set_addr):
	Changed signature.  Made static.
	(i386_dr_low_get_addr): Likewise.
	(i386_dr_low_set_control): Likewise.
	(i386_dr_low_get_control): Likewise.
	(i386_dr_low_get_status): Likewise.
	(i386_dr_low): New global variable.

2 files changed, 65 insertions, 3 deletions

diff --git a/gdb/nat/i386-dregs.c b/gdb/nat/i386-dregs.c
index 0067a90..e7d1620 100644
--- a/gdb/nat/i386-dregs.c
+++ b/gdb/nat/i386-dregs.c
@@ -19,12 +19,11 @@
 
 #ifdef GDBSERVER
 #include "server.h"
-#include "i386-low.h"
 #else
 #include "defs.h"
-#include "i386-nat.h"
 #include "inferior.h"
 #endif
+#include "nat/i386-dregs.h"
 
 /* Support for hardware watchpoints and breakpoints using the i386
    debug registers.
@@ -37,6 +36,35 @@
    The functions below implement debug registers sharing by reference
    counts, and allow to watch regions up to 16 bytes long.  */
 
+/* Accessor macros for low-level function vector.  */
+
+/* Can we update the inferior's debug registers?  */
+#define i386_dr_low_can_set_addr() (i386_dr_low.set_addr != NULL)
+
+/* Update the inferior's debug register REGNUM from STATE.  */
+#define i386_dr_low_set_addr(new_state, i) \
+  (i386_dr_low.set_addr ((i), (new_state)->dr_mirror[(i)]))
+
+/* Return the inferior's debug register REGNUM.  */
+#define i386_dr_low_get_addr(i) (i386_dr_low.get_addr ((i)))
+
+/* Can we update the inferior's DR7 control register?  */
+#define i386_dr_low_can_set_control() (i386_dr_low.set_control != NULL)
+
+/* Update the inferior's DR7 debug control register from STATE.  */
+#define i386_dr_low_set_control(new_state) \
+  (i386_dr_low.set_control ((new_state)->dr_control_mirror))
+
+/* Return the value of the inferior's DR7 debug control register.  */
+#define i386_dr_low_get_control() (i386_dr_low.get_control ())
+
+/* Return the value of the inferior's DR6 debug status register.  */
+#define i386_dr_low_get_status() (i386_dr_low.get_status ())
+
+/* Return the debug register size, in bytes.  */
+#define i386_get_debug_register_length() \
+  (i386_dr_low.debug_register_length)
+
 /* Support for 8-byte wide hw watchpoints.  */
 #define TARGET_HAS_DR_LEN_8 (i386_get_debug_register_length () == 8)
 
@@ -147,8 +175,11 @@
 /* Types of operations supported by i386_handle_nonaligned_watchpoint.  */
 typedef enum { WP_INSERT, WP_REMOVE, WP_COUNT } i386_wp_op_t;
 
-/* Print debugging messages.  */
 #ifndef GDBSERVER
+/* Whether or not to print the mirrored debug registers.  */
+extern int debug_hw_points;
+
+/* Print debugging messages.  */
 #define debug_printf(fmt, args...) \
   fprintf_unfiltered (gdb_stdlog, fmt, ##args);
 #endif
diff --git a/gdb/nat/i386-dregs.h b/gdb/nat/i386-dregs.h
index 58029ef..16edf63 100644
--- a/gdb/nat/i386-dregs.h
+++ b/gdb/nat/i386-dregs.h
@@ -35,6 +35,37 @@
 /* Forward declaration.  */
 enum target_hw_bp_type;
 
+/* Low-level function vector.  */
+
+struct i386_dr_low_type
+  {
+    /* Set the debug control (DR7) register to a given value for
+       all LWPs.  May be NULL if the debug control register cannot
+       be set.  */
+    void (*set_control) (unsigned long);
+
+    /* Put an address into one debug register for all LWPs.  May
+       be NULL if debug registers cannot be set*/
+    void (*set_addr) (int, CORE_ADDR);
+
+    /* Return the address in a given debug register of the current
+       LWP.  */
+    CORE_ADDR (*get_addr) (int);
+
+    /* Return the value of the debug status (DR6) register for
+       current LWP.  */
+    unsigned long (*get_status) (void);
+
+    /* Return the value of the debug control (DR7) register for
+       current LWP.  */
+    unsigned long (*get_control) (void);
+
+    /* Number of bytes used for debug registers (4 or 8).  */
+    int debug_register_length;
+  };
+
+extern struct i386_dr_low_type i386_dr_low;
+
 /* Debug registers' indices.  */
 #define DR_FIRSTADDR 0
 #define DR_LASTADDR  3