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.

2 files changed, 60 insertions, 0 deletions

diff --git a/gdb/common/common-regcache.c b/gdb/common/common-regcache.c
new file mode 100644
index 0000000..9ee1102
--- /dev/null
+++ b/gdb/common/common-regcache.c
@@ -0,0 +1,36 @@
+/* Cache and manage the values of registers for GDB, the GNU debugger.
+
+   Copyright (C) 2015 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "common-defs.h"
+#include "common-regcache.h"
+
+/* Return the register's value or throw if it's not available.  */
+
+ULONGEST
+regcache_raw_get_unsigned (struct regcache *regcache, int regnum)
+{
+  ULONGEST value;
+  enum register_status status;
+
+  status = regcache_raw_read_unsigned (regcache, regnum, &value);
+  if (status == REG_UNAVAILABLE)
+    throw_error (NOT_AVAILABLE_ERROR,
+		 _("Register %d is not available"), regnum);
+  return value;
+}
diff --git a/gdb/common/common-regcache.h b/gdb/common/common-regcache.h
index c470603..97c186c 100644
--- a/gdb/common/common-regcache.h
+++ b/gdb/common/common-regcache.h
@@ -22,6 +22,24 @@
 
 /* This header is a stopgap until we have an independent regcache.  */
 
+enum register_status
+  {
+    /* The register value is not in the cache, and we don't know yet
+       whether it's available in the target (or traceframe).  */
+    REG_UNKNOWN = 0,
+
+    /* The register value is valid and cached.  */
+    REG_VALID = 1,
+
+    /* The register value is unavailable.  E.g., we're inspecting a
+       traceframe, and this register wasn't collected.  Note that this
+       is different a different "unavailable" from saying the register
+       does not exist in the target's architecture --- in that case,
+       the target should have given us a target description that does
+       not include the register in the first place.  */
+    REG_UNAVAILABLE = -1
+  };
+
 /* Return a pointer to the register cache associated with the
    thread specified by PTID.  This function must be provided by
    the client.  */
@@ -38,4 +56,10 @@ extern int regcache_register_size (const struct regcache *regcache, int n);
 
 extern CORE_ADDR regcache_read_pc (struct regcache *regcache);
 
+/* Read a raw register into a unsigned integer.  */
+extern enum register_status regcache_raw_read_unsigned
+  (struct regcache *regcache, int regnum, ULONGEST *val);
+
+ULONGEST regcache_raw_get_unsigned (struct regcache *regcache, int regnum);
+
 #endif /* COMMON_REGCACHE_H */