Share regcache function regcache_raw_read_unsigned

This patch is in preparation for software single step support on ARM in
GDBServer. It adds a new shared function regcache_raw_read_unsigned and
regcache_raw_get_unsigned so that GDB and GDBServer can use the same call
to fetch a raw register into an integer.

No regressions, tested on ubuntu 14.04 ARMv7 and x86.
With gdbserver-{native,extended} / { -marm -mthumb }

gdb/ChangeLog:

	* Makefile.in (SFILES): Append common/common-regcache.c.
	(COMMON_OBS): Append common/common-regcache.o.
	(common-regcache.o): New rule.
	* common/common-regcache.h (register_status) New enum.
	(regcache_raw_read_unsigned): New declaration.
	* common/common-regcache.c: New file.
	* regcache.h (enum register_status): Move to common-regcache.h.
	(regcache_raw_read_unsigned): Likewise.
	(regcache_raw_get_unsigned): Likewise.

gdb/gdbserver/ChangeLog:

	* Makefile.in (SFILES): Append common/common-regcache.c.
	(OBS): Append common-regcache.o.
	(common-regcache.o): New rule.
	* regcache.c (init_register_cache): Initialize cache to
	REG_UNAVAILABLE.
	(regcache_raw_read_unsigned): New function.
	* regcache.h (REG_UNAVAILABLE, REG_VALID): Replaced by shared
	register_status enum.

1 files changed, 24 insertions, 2 deletions

diff --git a/gdb/gdbserver/regcache.c b/gdb/gdbserver/regcache.c
index b9311fe..c608bf3 100644
--- a/gdb/gdbserver/regcache.c
+++ b/gdb/gdbserver/regcache.c
@@ -145,8 +145,9 @@ init_register_cache (struct regcache *regcache,
 	= (unsigned char *) xcalloc (1, tdesc->registers_size);
       regcache->registers_owned = 1;
       regcache->register_status
-	= (unsigned char *) xcalloc (1, tdesc->num_registers);
-      gdb_assert (REG_UNAVAILABLE == 0);
+	= (unsigned char *) xmalloc (tdesc->num_registers);
+      memset ((void *) regcache->register_status, REG_UNAVAILABLE,
+	      tdesc->num_registers);
 #else
       gdb_assert_not_reached ("can't allocate memory from the heap");
 #endif
@@ -435,6 +436,27 @@ collect_register (struct regcache *regcache, int n, void *buf)
 	  register_size (regcache->tdesc, n));
 }
 
+enum register_status
+regcache_raw_read_unsigned (struct regcache *regcache, int regnum,
+			    ULONGEST *val)
+{
+  int size;
+
+  gdb_assert (regcache != NULL);
+  gdb_assert (regnum >= 0 && regnum < regcache->tdesc->num_registers);
+
+  size = register_size (regcache->tdesc, regnum);
+
+  if (size > (int) sizeof (ULONGEST))
+    error (_("That operation is not available on integers of more than"
+            "%d bytes."),
+          (int) sizeof (ULONGEST));
+
+  collect_register (regcache, regnum, val);
+
+  return REG_VALID;
+}
+
 #ifndef IN_PROCESS_AGENT
 
 void