Class readonly_detached_regcache

This patch adds a new class (type) for readonly regcache, which is
created via regcache::save.  readonly_detached_regcache inherits
readable_regcache.

gdb:

2018-02-21  Yao Qi  <yao.qi@linaro.org>

	* dummy-frame.c (dummy_frame_cache) <prev_regcache>: Use
	readonly_detached_regcache.
	(dummy_frame_prev_register): Use regcache->cooked_read.
	* frame.c (frame_save_as_regcache): Change return type.
	(frame_pop): Update.
	* frame.h (frame_save_as_regcache): Update declaration.
	* inferior.h (get_infcall_suspend_state_regcache): Update
	declaration.
	* infrun.c (infcall_suspend_state) <registers>: use
	readonly_detached_regcache.
	(save_infcall_suspend_state): Don't use regcache_dup.
	(get_infcall_suspend_state_regcache): Change return type.
	* linux-fork.c (struct fork_info) <savedregs>: Change to
	readonly_detached_regcache.
	<pc>: New field.
	(fork_save_infrun_state): Don't use regcache_dup.
	(info_checkpoints_command): Adjust.
	* mi/mi-main.c (register_changed_p): Update declaration.
	(mi_cmd_data_list_changed_registers): Use
	readonly_detached_regcache.
	(register_changed_p): Change parameter type to
	readonly_detached_regcache.
	* ppc-linux-tdep.c (ppu2spu_cache) <regcache>: Use
	readonly_detached_regcache.
	(ppu2spu_sniffer): Construct a new readonly_detached_regcache.
	* regcache.c (readonly_detached_regcache::readonly_detached_regcache):
	New.
	(regcache::save): Move it to reg_buffer.
	(regcache::restore): Change parameter type.
	(regcache_dup): Remove.
	* regcache.h (reg_buffer) <save>: New method.
	(readonly_detached_regcache): New class.
	* spu-tdep.c (spu2ppu_cache) <regcache>: Use
	readonly_detached_regcache.
	(spu2ppu_sniffer): Construct a new readonly_detached_regcache.

1 files changed, 33 insertions, 11 deletions

diff --git a/gdb/regcache.h b/gdb/regcache.h
index a4ca2ec..4ad0060 100644
--- a/gdb/regcache.h
+++ b/gdb/regcache.h
@@ -243,6 +243,11 @@ protected:
 
   gdb_byte *register_buffer (int regnum) const;
 
+  /* Save a register cache.  The set of registers saved into the
+     regcache determined by the save_reggroup.  COOKED_READ returns
+     zero iff the register's value can't be returned.  */
+  void save (regcache_cooked_read_ftype *cooked_read, void *src);
+
   struct regcache_descr *m_descr;
 
   bool m_has_pseudo;
@@ -250,6 +255,8 @@ protected:
   gdb_byte *m_registers;
   /* Register cache status.  */
   signed char *m_register_status;
+
+  friend class regcache;
 };
 
 /* An abstract class which only has methods doing read.  */
@@ -284,6 +291,8 @@ protected:
 				  bool is_raw);
 };
 
+class readonly_detached_regcache;
+
 /* The register cache for storing raw register values.  */
 
 class regcache : public readable_regcache
@@ -307,15 +316,11 @@ public:
     return m_aspace;
   }
 
-/* Save/restore 'this' regcache.  The set of registers saved /
-   restored into the regcache determined by the save_reggroup /
-   restore_reggroup respectively.  COOKED_READ returns zero iff the
-   register's value can't be returned.  */
-  void save (regcache_cooked_read_ftype *cooked_read, void *src);
-
-  /* Writes to regcache will go through to the target.  SRC is a
+  /* Restore 'this' regcache.  The set of registers restored into
+     the regcache determined by the restore_reggroup.
+     Writes to regcache will go through to the target.  SRC is a
      read-only register cache.  */
-  void restore (struct regcache *src);
+  void restore (readonly_detached_regcache *src);
 
   void cooked_write (int regnum, const gdb_byte *buf);
 
@@ -413,9 +418,26 @@ private:
   registers_changed_ptid (ptid_t ptid);
 };
 
-/* Duplicate the contents of a register cache to a read-only register
-   cache.  The operation is pass-through.  */
-extern struct regcache *regcache_dup (struct regcache *regcache);
+class readonly_detached_regcache : public readable_regcache
+{
+public:
+  readonly_detached_regcache (const regcache &src);
+
+  /* Create a readonly regcache by getting contents from COOKED_READ.  */
+
+  readonly_detached_regcache (gdbarch *gdbarch,
+			      regcache_cooked_read_ftype *cooked_read,
+			      void *src)
+    : readable_regcache (gdbarch, true)
+  {
+    save (cooked_read, src);
+  }
+
+  DISABLE_COPY_AND_ASSIGN (readonly_detached_regcache);
+
+  void raw_update (int regnum) override
+  {}
+};
 
 extern void registers_changed (void);
 extern void registers_changed_ptid (ptid_t);