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.

gdb/gdbserver/ChangeLog

@@ -1,3 +1,14 @@
+2015-12-18  Antoine Tremblay  <antoine.tremblay@ericsson.com>
+
+	* 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.
+
 2015-12-18  Antoine Tremblay  <antoine.tremblay@ericsson.com>
 
 	* linux-aarch64-low.c (the_low_targets): Rename

gdb/gdbserver/Makefile.in

@@ -181,7 +181,7 @@ SFILES=	$(srcdir)/gdbreplay.c $(srcdir)/inferiors.c $(srcdir)/dll.c \
 	$(srcdir)/common/common-exceptions.c $(srcdir)/symbol.c \
 	$(srcdir)/common/btrace-common.c \
 	$(srcdir)/common/fileio.c $(srcdir)/nat/linux-namespaces.c \
-	$(srcdir)/arch/arm.c
+	$(srcdir)/arch/arm.c $(srcdir)/common/common-regcache.c
 
 DEPFILES = @GDBSERVER_DEPFILES@
 
@@ -195,7 +195,7 @@ OBS = agent.o ax.o inferiors.o regcache.o remote-utils.o server.o signals.o \
       mem-break.o hostio.o event-loop.o tracepoint.o xml-utils.o \
       common-utils.o ptid.o buffer.o format.o filestuff.o dll.o notif.o \
       tdesc.o print-utils.o rsp-low.o errors.o common-debug.o cleanups.o \
-      common-exceptions.o symbol.o btrace-common.o fileio.o \
+      common-exceptions.o symbol.o btrace-common.o fileio.o common-regcache.o \
       $(XML_BUILTIN) $(DEPFILES) $(LIBOBJS)
 GDBREPLAY_OBS = gdbreplay.o version.o
 GDBSERVER_LIBS = @GDBSERVER_LIBS@
@@ -583,6 +583,9 @@ waitstatus.o: ../target/waitstatus.c
 fileio.o: ../common/fileio.c
 	$(COMPILE) $<
 	$(POSTCOMPILE)
+common-regcache.o: ../common/common-regcache.c
+	$(COMPILE) $<
+	$(POSTCOMPILE)
 
 # Arch object files rules form ../arch
 

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

gdb/gdbserver/regcache.h

@@ -24,13 +24,6 @@
 struct thread_info;
 struct target_desc;
 
-/* The register exists, it has a value, but we don't know what it is.
-   Used when inspecting traceframes.  */
-#define REG_UNAVAILABLE 0
-
-/* We know the register's value (and we have it cached).  */
-#define REG_VALID 1
-
 /* The data for the register cache.  Note that we have one per
    inferior; this is primarily for simplicity, as the performance
    benefit is minimal.  */