Rename regcache_cooked_read_ftype and make a function_view

regcache_cooked_read_ftype can be converted to a function_view, which
allows us to use lambda functions and therefore avoid having to pass an
opaque pointer parameter.

Adjusting the fallouts showed that the "const regcache &" passed to the
readonly_detached_regcache constructor is cast to non-const in
do_cooked_read.  I changed the constructor parameter to be non-const.

Finally, I renamed the typedef from regcache_cooked_read_ftype to
register_read_ftype, since there is nothing that forces us to use it
only for regcaches nor cooked registers.

gdb/ChangeLog:

	* regcache.h (regcache_cooked_read_ftype): Rename to...
	(register_read_ftype): ...this, change type to function_view.
	(class reg_buffer) <save>: Remove src parameter.
	(readonly_detached_regcache) <readonly_detached_regcache>: Make
	parameter non-const in first overload.  Remove src parameter in
	second overload.
	* regcache.c (do_cooked_read): Remove.
	(readonly_detached_regcache::readonly_detached_regcache): Make
	parameter non-const, adjust call to other constructor.
	(reg_buffer::save): Remove src parameter.
	* frame.c (do_frame_register_read): Remove.
	(frame_save_as_regcache): Use lambda function.
	* ppc-linux-tdep.c (ppu2spu_unwind_register): Change type of src
	parameter to ppu2spu_data *.
	(ppu2spu_sniffer): Use lambda function.

gdb/ChangeLog

@@ -1,3 +1,21 @@
+2018-06-20  Simon Marchi  <simon.marchi@polymtl.ca>
+
+	* regcache.h (regcache_cooked_read_ftype): Rename to...
+	(register_read_ftype): ...this, change type to function_view.
+	(class reg_buffer) <save>: Remove src parameter.
+	(readonly_detached_regcache) <readonly_detached_regcache>: Make
+	parameter non-const in first overload.  Remove src parameter in
+	second overload.
+	* regcache.c (do_cooked_read): Remove.
+	(readonly_detached_regcache::readonly_detached_regcache): Make
+	parameter non-const, adjust call to other constructor.
+	(reg_buffer::save): Remove src parameter.
+	* frame.c (do_frame_register_read): Remove.
+	(frame_save_as_regcache): Use lambda function.
+	* ppc-linux-tdep.c (ppu2spu_unwind_register): Change type of src
+	parameter to ppu2spu_data *.
+	(ppu2spu_sniffer): Use lambda function.
+
 2018-06-20  Simon Marchi  <simon.marchi@polymtl.ca>
 
 	* record-full.c (record_full_target::insert_breakpoint): Remove

gdb/frame.c

@@ -1024,21 +1024,19 @@ get_frame_func (struct frame_info *this_frame)
   return pc;
 }
 
-static enum register_status
-do_frame_register_read (void *src, int regnum, gdb_byte *buf)
-{
-  if (!deprecated_frame_register_read ((struct frame_info *) src, regnum, buf))
-    return REG_UNAVAILABLE;
-  else
-    return REG_VALID;
-}
-
 std::unique_ptr<readonly_detached_regcache>
 frame_save_as_regcache (struct frame_info *this_frame)
 {
+  auto cooked_read = [this_frame] (int regnum, gdb_byte *buf)
+    {
+      if (!deprecated_frame_register_read (this_frame, regnum, buf))
+	return REG_UNAVAILABLE;
+      else
+	return REG_VALID;
+    };
+
   std::unique_ptr<readonly_detached_regcache> regcache
-    (new readonly_detached_regcache (get_frame_arch (this_frame),
-				     do_frame_register_read, this_frame));
+    (new readonly_detached_regcache (get_frame_arch (this_frame), cooked_read));
 
   return regcache;
 }

gdb/ppc-linux-tdep.c

@@ -1371,9 +1371,8 @@ struct ppu2spu_data
 };
 
 static enum register_status
-ppu2spu_unwind_register (void *src, int regnum, gdb_byte *buf)
+ppu2spu_unwind_register (ppu2spu_data *data, int regnum, gdb_byte *buf)
 {
-  struct ppu2spu_data *data = (struct ppu2spu_data *) src;
   enum bfd_endian byte_order = gdbarch_byte_order (data->gdbarch);
 
   if (regnum >= 0 && regnum < SPU_NUM_GPRS)
@@ -1435,12 +1434,14 @@ ppu2spu_sniffer (const struct frame_unwind *self,
 		       data.gprs, 0, sizeof data.gprs)
 	  == sizeof data.gprs)
 	{
+	  auto cooked_read = [&data] (int regnum, gdb_byte *buf)
+	    {
+	      return ppu2spu_unwind_register (&data, regnum, buf);
+	    };
 	  struct ppu2spu_cache *cache
 	    = FRAME_OBSTACK_CALLOC (1, struct ppu2spu_cache);
 	  std::unique_ptr<readonly_detached_regcache> regcache
-	    (new readonly_detached_regcache (data.gdbarch,
-					     ppu2spu_unwind_register,
-					     &data));
+	    (new readonly_detached_regcache (data.gdbarch, cooked_read));
 
 	  cache->frame_id = frame_id_build (base, func);
 	  cache->regcache = regcache.release ();

gdb/regcache.c

@@ -205,16 +205,12 @@ regcache::regcache (gdbarch *gdbarch, const address_space *aspace_)
   m_ptid = minus_one_ptid;
 }
 
-static enum register_status
-do_cooked_read (void *src, int regnum, gdb_byte *buf)
-{
-  struct regcache *regcache = (struct regcache *) src;
-
-  return regcache->cooked_read (regnum, buf);
-}
-
-readonly_detached_regcache::readonly_detached_regcache (const regcache &src)
-  : readonly_detached_regcache (src.arch (), do_cooked_read, (void *) &src)
+readonly_detached_regcache::readonly_detached_regcache (regcache &src)
+  : readonly_detached_regcache (src.arch (),
+				[&src] (int regnum, gdb_byte *buf)
+				  {
+				    return src.cooked_read (regnum, buf);
+				  })
 {
 }
 
@@ -264,8 +260,7 @@ reg_buffer::register_buffer (int regnum) const
 }
 
 void
-reg_buffer::save (regcache_cooked_read_ftype *cooked_read,
-		  void *src)
+reg_buffer::save (register_read_ftype cooked_read)
 {
   struct gdbarch *gdbarch = m_descr->gdbarch;
   int regnum;
@@ -284,7 +279,7 @@ reg_buffer::save (regcache_cooked_read_ftype *cooked_read,
       if (gdbarch_register_reggroup_p (gdbarch, regnum, save_reggroup))
 	{
 	  gdb_byte *dst_buf = register_buffer (regnum);
-	  enum register_status status = cooked_read (src, regnum, dst_buf);
+	  enum register_status status = cooked_read (regnum, dst_buf);
 
 	  gdb_assert (status != REG_UNKNOWN);
 

gdb/regcache.h

@@ -125,9 +125,8 @@ extern struct type *register_type (struct gdbarch *gdbarch, int regnum);
    
 extern int register_size (struct gdbarch *gdbarch, int regnum);
 
-typedef enum register_status (regcache_cooked_read_ftype) (void *src,
-							   int regnum,
-							   gdb_byte *buf);
+typedef gdb::function_view<register_status (int regnum, gdb_byte *buf)>
+  register_read_ftype;
 
 /* A (register_number, register_value) pair.  */
 
@@ -202,7 +201,7 @@ protected:
   /* 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);
+  void save (register_read_ftype cooked_read);
 
   struct regcache_descr *m_descr;
 
@@ -379,16 +378,14 @@ private:
 class readonly_detached_regcache : public readable_regcache
 {
 public:
-  readonly_detached_regcache (const regcache &src);
+  readonly_detached_regcache (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)
+  readonly_detached_regcache (gdbarch *gdbarch, register_read_ftype cooked_read)
     : readable_regcache (gdbarch, true)
   {
-    save (cooked_read, src);
+    save (cooked_read);
   }
 
   DISABLE_COPY_AND_ASSIGN (readonly_detached_regcache);