2010-12-15  Yao Qi  <yao@codesourcery.com>

	* arm-tdep.c (arm_user_register_name): New.
	(arm_gdbarch_init): Install arm_user_register_nam on gdbarch hook
	user_register_name.

diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index 636c1de..618f82f 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -2918,6 +2918,27 @@ arm_neon_quad_type (struct gdbarch *gdbarch)
   return tdep->neon_quad_type;
 }
 
+static int
+arm_user_register_name (struct gdbarch *gdbarch, const char *regname, int len)
+{
+  if ((len < 0 && strcmp ("fp", regname))
+      || (len == strlen ("fp")
+	  && strncmp ("fp", regname, len) == 0))
+    {
+      /* `fp' register means different registers on ARM and Thumb.  Return
+	 the correct `fp' register number according the state of current
+	 frame.  */
+      struct frame_info *frame = get_selected_frame (NULL);
+      if (arm_frame_is_thumb (frame))
+	return THUMB_FP_REGNUM;
+      else
+	return ARM_FP_REGNUM;
+    }
+  else
+    /* Leave search to other registers to default implementation.  */
+    return default_user_register_name (gdbarch, regname, len);
+}
+
 /* Return the GDB type object for the "standard" data type of data in
    register N.  */
 
@@ -7462,6 +7483,7 @@ arm_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   set_gdbarch_pc_regnum (gdbarch, ARM_PC_REGNUM);
   set_gdbarch_num_regs (gdbarch, ARM_NUM_REGS);
   set_gdbarch_register_type (gdbarch, arm_register_type);
+  set_gdbarch_user_register_name (gdbarch, arm_user_register_name);
 
   /* This "info float" is FPA-specific.  Use the generic version if we
      do not have FPA.  */