[PATCH 7/7]: Regcache: Refactor raw_set_cached_value

gdb/frame.c

@@ -1021,13 +1021,12 @@ struct regcache *
 frame_save_as_regcache (struct frame_info *this_frame)
 {
   struct address_space *aspace = get_frame_address_space (this_frame);
-  struct regcache *regcache = regcache_xmalloc (get_frame_arch (this_frame),
-						aspace);
-  struct cleanup *cleanups = make_cleanup_regcache_xfree (regcache);
+  regcache *backup = new regcache (get_frame_arch (this_frame), aspace);
+  struct cleanup *cleanups = make_cleanup_regcache_delete (backup);
 
-  regcache_save (regcache, do_frame_register_read, this_frame);
+  backup->save (do_frame_register_read, this_frame);
   discard_cleanups (cleanups);
-  return regcache;
+  return backup;
 }
 
 void
@@ -1063,7 +1062,7 @@ frame_pop (struct frame_info *this_frame)
      trying to extract the old values from the current regcache while
      at the same time writing new values into that same cache.  */
   scratch = frame_save_as_regcache (prev_frame);
-  cleanups = make_cleanup_regcache_xfree (scratch);
+  cleanups = make_cleanup_regcache_delete (scratch);
 
   /* FIXME: cagney/2003-03-16: It should be possible to tell the
      target's register cache that it is about to be hit with a burst
@@ -1073,9 +1072,8 @@ frame_pop (struct frame_info *this_frame)
      Unfortunately, they don't implement it.  Their lack of a formal
      definition can lead to targets writing back bogus values
      (arguably a bug in the target code mind).  */
-  /* Now copy those saved registers into the current regcache.
-     Here, regcache_cpy() calls regcache_restore().  */
-  regcache_cpy (get_current_regcache (), scratch);
+  /* Now copy those saved registers into the current regcache.  */
+  scratch->restore_to (get_current_regcache ());
   do_cleanups (cleanups);
 
   /* We've made right mess of GDB's local state, just discard

gdb/gdbarch-selftests.c

@@ -27,11 +27,11 @@ namespace selftests {
 
 /* A read-write regcache which doesn't write the target.  */
 
-class regcache_test : public regcache
+class regcache_test : public target_regcache
 {
 public:
   explicit regcache_test (struct gdbarch *gdbarch)
-    : regcache (gdbarch, NULL, false)
+    : target_regcache (gdbarch, NULL)
   {
     set_ptid (inferior_ptid);
 
@@ -40,7 +40,8 @@ public:
 
   void raw_write (int regnum, const gdb_byte *buf) override
   {
-    raw_set_cached_value (regnum, buf);
+    /* Bypass writing to the target.  */
+    regcache::raw_write (regnum, buf);
   }
 };
 

gdb/infcmd.c

@@ -1602,8 +1602,8 @@ advance_command (char *arg, int from_tty)
 struct value *
 get_return_value (struct value *function, struct type *value_type)
 {
-  regcache stop_regs (regcache::readonly, *get_current_regcache ());
-  struct gdbarch *gdbarch = stop_regs.arch ();
+  regcache *stop_regs = get_current_regcache ()->dup ();
+  struct gdbarch *gdbarch = stop_regs->arch ();
   struct value *value;
 
   value_type = check_typedef (value_type);
@@ -1623,7 +1623,7 @@ get_return_value (struct value *function, struct type *value_type)
     case RETURN_VALUE_ABI_RETURNS_ADDRESS:
     case RETURN_VALUE_ABI_PRESERVES_ADDRESS:
       value = allocate_value (value_type);
-      gdbarch_return_value (gdbarch, function, value_type, &stop_regs,
+      gdbarch_return_value (gdbarch, function, value_type, stop_regs,
 			    value_contents_raw (value), NULL);
       break;
     case RETURN_VALUE_STRUCT_CONVENTION:
@@ -1633,6 +1633,7 @@ get_return_value (struct value *function, struct type *value_type)
       internal_error (__FILE__, __LINE__, _("bad switch"));
     }
 
+  delete stop_regs;
   return value;
 }
 

gdb/infrun.c

@@ -8911,7 +8911,7 @@ save_infcall_suspend_state (void)
 
   inf_state->stop_pc = stop_pc;
 
-  inf_state->registers = regcache_dup (regcache);
+  inf_state->registers = regcache->dup ();
 
   return inf_state;
 }
@@ -8922,7 +8922,7 @@ void
 restore_infcall_suspend_state (struct infcall_suspend_state *inf_state)
 {
   struct thread_info *tp = inferior_thread ();
-  struct regcache *regcache = get_current_regcache ();
+  target_regcache *regcache = get_current_regcache ();
   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 
   tp->suspend = inf_state->thread_suspend;
@@ -8942,7 +8942,7 @@ restore_infcall_suspend_state (struct infcall_suspend_state *inf_state)
      (and perhaps other times).  */
   if (target_has_execution)
     /* NB: The register write goes through to the target.  */
-    regcache_cpy (regcache, inf_state->registers);
+    inf_state->registers->restore_to (regcache);
 
   discard_infcall_suspend_state (inf_state);
 }
@@ -8963,7 +8963,7 @@ make_cleanup_restore_infcall_suspend_state
 void
 discard_infcall_suspend_state (struct infcall_suspend_state *inf_state)
 {
-  regcache_xfree (inf_state->registers);
+  delete inf_state->registers;
   xfree (inf_state->siginfo_data);
   xfree (inf_state);
 }

gdb/jit.c

@@ -1125,7 +1125,7 @@ jit_unwind_reg_set_impl (struct gdb_unwind_callbacks *cb, int dwarf_regnum,
       return;
     }
 
-  regcache_raw_set_cached_value (priv->regcache, gdb_reg, value->value);
+  priv->regcache->raw_supply (gdb_reg, value->value);
   value->free (value);
 }
 
@@ -1168,7 +1168,7 @@ jit_dealloc_cache (struct frame_info *this_frame, void *cache)
   struct jit_unwind_private *priv_data = (struct jit_unwind_private *) cache;
 
   gdb_assert (priv_data->regcache != NULL);
-  regcache_xfree (priv_data->regcache);
+  delete priv_data->regcache;
   xfree (priv_data);
 }
 
@@ -1206,7 +1206,7 @@ jit_frame_sniffer (const struct frame_unwind *self,
 
   *cache = XCNEW (struct jit_unwind_private);
   priv_data = (struct jit_unwind_private *) *cache;
-  priv_data->regcache = regcache_xmalloc (gdbarch, aspace);
+  priv_data->regcache = new regcache (gdbarch, aspace, false);
   priv_data->this_frame = this_frame;
 
   callbacks.priv_data = priv_data;

gdb/linux-fork.c

@@ -129,7 +129,7 @@ free_fork (struct fork_info *fp)
   if (fp)
     {
       if (fp->savedregs)
-	regcache_xfree (fp->savedregs);
+	delete fp->savedregs;
       if (fp->filepos)
 	xfree (fp->filepos);
       xfree (fp);
@@ -264,7 +264,7 @@ fork_load_infrun_state (struct fork_info *fp)
   linux_nat_switch_fork (fp->ptid);
 
   if (fp->savedregs && fp->clobber_regs)
-    regcache_cpy (get_current_regcache (), fp->savedregs);
+     fp->savedregs->restore_to (get_current_regcache ());
 
   registers_changed ();
   reinit_frame_cache ();
@@ -295,9 +295,9 @@ fork_save_infrun_state (struct fork_info *fp, int clobber_regs)
   DIR *d;
 
   if (fp->savedregs)
-    regcache_xfree (fp->savedregs);
+    delete fp->savedregs;
 
-  fp->savedregs = regcache_dup (get_current_regcache ());
+  fp->savedregs = get_current_regcache ()->dup ();
   fp->clobber_regs = clobber_regs;
 
   if (clobber_regs)

gdb/mi/mi-main.c

@@ -1051,7 +1051,7 @@ mi_cmd_data_list_changed_registers (const char *command, char **argv, int argc)
 
   prev_regs = this_regs;
   this_regs = frame_save_as_regcache (get_selected_frame (NULL));
-  cleanup = make_cleanup_regcache_xfree (prev_regs);
+  cleanup = make_cleanup_regcache_delete (prev_regs);
 
   /* Note that the test for a valid register must include checking the
      gdbarch_register_name because gdbarch_num_regs may be allocated

gdb/ppc-linux-tdep.c

@@ -1364,13 +1364,13 @@ ppu2spu_sniffer (const struct frame_unwind *self,
 	    = FRAME_OBSTACK_CALLOC (1, struct ppu2spu_cache);
 
 	  struct address_space *aspace = get_frame_address_space (this_frame);
-	  struct regcache *regcache = regcache_xmalloc (data.gdbarch, aspace);
-	  struct cleanup *cleanups = make_cleanup_regcache_xfree (regcache);
-	  regcache_save (regcache, ppu2spu_unwind_register, &data);
+	  regcache *backup = new regcache (data.gdbarch, aspace);
+	  struct cleanup *cleanups = make_cleanup_regcache_delete (backup);
+	  backup->save (ppu2spu_unwind_register, &data);
 	  discard_cleanups (cleanups);
 
 	  cache->frame_id = frame_id_build (base, func);
-	  cache->regcache = regcache;
+	  cache->regcache = backup;
 	  *this_prologue_cache = cache;
 	  return 1;
 	}
@@ -1383,7 +1383,7 @@ static void
 ppu2spu_dealloc_cache (struct frame_info *self, void *this_cache)
 {
   struct ppu2spu_cache *cache = (struct ppu2spu_cache *) this_cache;
-  regcache_xfree (cache->regcache);
+  delete cache->regcache;
 }
 
 static const struct frame_unwind ppu2spu_unwind = {

gdb/regcache.c

@@ -189,25 +189,36 @@ regcache_register_size (const struct regcache *regcache, int n)
 }
 
 regcache::regcache (gdbarch *gdbarch, address_space *aspace_,
-		    bool readonly_p_)
+		    bool readonly_p_, bool allocate_registers)
   : m_aspace (aspace_), m_readonly_p (readonly_p_)
 {
   gdb_assert (gdbarch != NULL);
   m_descr = regcache_descr (gdbarch);
 
-  if (m_readonly_p)
+  if (allocate_registers)
     {
+      /* Need extra space to store the additional cooked registers for when
+	 the detached regcache is used to save a regcache.  */
       m_registers = XCNEWVEC (gdb_byte, m_descr->sizeof_cooked_registers);
-      m_register_status = XCNEWVEC (signed char,
-				    m_descr->sizeof_cooked_register_status);
-    }
-  else
-    {
-      m_registers = XCNEWVEC (gdb_byte, m_descr->sizeof_raw_registers);
-      m_register_status = XCNEWVEC (signed char,
-				    m_descr->sizeof_raw_register_status);
     }
+
+  /* All status' are initialised to REG_UNKNOWN.  */
+  m_register_status = XCNEWVEC (signed char,
+				m_descr->sizeof_cooked_register_status);
+}
+
+target_regcache::target_regcache (gdbarch *gdbarch, address_space *aspace_)
+  : regcache (gdbarch, aspace_, false, false)
+{
+  /* Only allocate the raw registers - cooked registers are not cached.
+     Note that the register status is still fully allocated, to allow the
+     checking of the state of any register.  */
+  m_registers = XCNEWVEC (gdb_byte, m_descr->sizeof_raw_registers);
+
   m_ptid = minus_one_ptid;
+
+  /* A target_regcache should never be readonly.  */
+  gdb_assert (!m_readonly_p);
 }
 
 static enum register_status
@@ -218,13 +229,6 @@ do_cooked_read (void *src, int regnum, gdb_byte *buf)
   return regcache_cooked_read (regcache, regnum, buf);
 }
 
-regcache::regcache (readonly_t, const regcache &src)
-  : regcache (src.arch (), src.aspace (), true)
-{
-  gdb_assert (!src.m_readonly_p);
-  save (do_cooked_read, (void *) &src);
-}
-
 gdbarch *
 regcache::arch () const
 {
@@ -241,31 +245,18 @@ regcache_get_ptid (const struct regcache *regcache)
   return regcache->ptid ();
 }
 
-struct regcache *
-regcache_xmalloc (struct gdbarch *gdbarch, struct address_space *aspace)
-{
-  return new regcache (gdbarch, aspace);
-}
-
-void
-regcache_xfree (struct regcache *regcache)
-{
-  if (regcache == NULL)
-    return;
-
-  delete regcache;
-}
-
 static void
-do_regcache_xfree (void *data)
+do_regcache_delete (void *data)
 {
-  regcache_xfree ((struct regcache *) data);
+  if (data == NULL)
+    return;
+  delete (regcache *) data;
 }
 
 struct cleanup *
-make_cleanup_regcache_xfree (struct regcache *regcache)
+make_cleanup_regcache_delete (struct regcache *regcache)
 {
-  return make_cleanup (do_regcache_xfree, regcache);
+  return make_cleanup (do_regcache_delete, regcache);
 }
 
 /* Cleanup routines for invalidating a register.  */
@@ -317,23 +308,11 @@ regcache::register_buffer (int regnum) const
 }
 
 void
-regcache_save (struct regcache *regcache,
-	       regcache_cooked_read_ftype *cooked_read, void *src)
-{
-  regcache->save (cooked_read, src);
-}
-
-void
-regcache::save (regcache_cooked_read_ftype *cooked_read,
-		void *src)
+regcache::save (regcache_cooked_read_ftype *cooked_read, void *src)
 {
   struct gdbarch *gdbarch = m_descr->gdbarch;
   int regnum;
 
-  /* The DST should be `read-only', if it wasn't then the save would
-     end up trying to write the register values back out to the
-     target.  */
-  gdb_assert (m_readonly_p);
   /* Clear the dest.  */
   memset (m_registers, 0, m_descr->sizeof_cooked_registers);
   memset (m_register_status, 0, m_descr->sizeof_cooked_register_status);
@@ -359,15 +338,14 @@ regcache::save (regcache_cooked_read_ftype *cooked_read,
 }
 
 void
-regcache::restore (struct regcache *src)
+regcache::restore_to (target_regcache *dst)
 {
   struct gdbarch *gdbarch = m_descr->gdbarch;
   int regnum;
+  gdb_assert (dst != NULL);
+  gdb_assert (dst->m_descr->gdbarch == m_descr->gdbarch);
+  gdb_assert (dst != this);
 
-  /* The dst had better not be read-only.  If it is, the `restore'
-     doesn't make much sense.  */
-  gdb_assert (!m_readonly_p);
-  gdb_assert (src->m_readonly_p);
   /* Copy over any registers, being careful to only restore those that
      were both saved and need to be restored.  The full [0 .. gdbarch_num_regs
      + gdbarch_num_pseudo_regs) range is checked since some architectures need
@@ -376,27 +354,33 @@ regcache::restore (struct regcache *src)
     {
       if (gdbarch_register_reggroup_p (gdbarch, regnum, restore_reggroup))
 	{
-	  if (src->m_register_status[regnum] == REG_VALID)
-	    cooked_write (regnum, src->register_buffer (regnum));
+	  if (m_register_status[regnum] == REG_VALID)
+	    dst->cooked_write (regnum, register_buffer (regnum));
 	}
     }
 }
 
-void
-regcache_cpy (struct regcache *dst, struct regcache *src)
+/* Duplicate detached regcache to a detached regcache.  */
+regcache*
+regcache::dup (bool readonly_p)
 {
-  gdb_assert (src != NULL && dst != NULL);
-  gdb_assert (src->m_descr->gdbarch == dst->m_descr->gdbarch);
-  gdb_assert (src != dst);
-  gdb_assert (src->m_readonly_p && !dst->m_readonly_p);
+  regcache *new_regcache = new regcache (arch (), aspace (), readonly_p);
 
-  dst->restore (src);
+  memcpy (new_regcache->m_registers, m_registers,
+	  m_descr->sizeof_cooked_registers);
+  memcpy (new_regcache->m_register_status, m_register_status,
+	  m_descr->sizeof_cooked_register_status);
+
+  return new_regcache;
 }
 
-struct regcache *
-regcache_dup (struct regcache *src)
+/* Duplicate a target_regcache to a detached regcache.  */
+regcache*
+target_regcache::dup (bool readonly_p)
 {
-  return new regcache (regcache::readonly, *src);
+  regcache *new_regcache = new regcache (arch (), aspace (), readonly_p);
+  new_regcache->save (do_cooked_read, (void *) this);
+  return new_regcache;
 }
 
 enum register_status
@@ -410,14 +394,17 @@ enum register_status
 regcache::get_register_status (int regnum) const
 {
   gdb_assert (regnum >= 0);
-  if (m_readonly_p)
-    gdb_assert (regnum < m_descr->nr_cooked_registers);
-  else
-    gdb_assert (regnum < m_descr->nr_raw_registers);
-
+  gdb_assert (regnum < m_descr->nr_cooked_registers);
   return (enum register_status) m_register_status[regnum];
 }
 
+enum register_status
+target_regcache::get_register_status (int regnum) const
+{
+  gdb_assert (regnum < m_descr->nr_raw_registers);
+  return regcache::get_register_status (regnum);
+}
+
 void
 regcache_invalidate (struct regcache *regcache, int regnum)
 {
@@ -440,25 +427,25 @@ regcache::invalidate (int regnum)
    recording if the register values have been changed (eg. by the
    user).  Therefore all registers must be written back to the
    target when appropriate.  */
-std::forward_list<regcache *> regcache::current_regcache;
+std::forward_list<target_regcache *> target_regcache::current_regcache;
 
-struct regcache *
+target_regcache *
 get_thread_arch_aspace_regcache (ptid_t ptid, struct gdbarch *gdbarch,
 				 struct address_space *aspace)
 {
-  for (const auto &regcache : regcache::current_regcache)
+  for (const auto &regcache : target_regcache::current_regcache)
     if (ptid_equal (regcache->ptid (), ptid) && regcache->arch () == gdbarch)
       return regcache;
 
-  regcache *new_regcache = new regcache (gdbarch, aspace, false);
+  target_regcache *new_regcache = new target_regcache (gdbarch, aspace);
 
-  regcache::current_regcache.push_front (new_regcache);
+  target_regcache::current_regcache.push_front (new_regcache);
   new_regcache->set_ptid (ptid);
 
   return new_regcache;
 }
 
-struct regcache *
+target_regcache *
 get_thread_arch_regcache (ptid_t ptid, struct gdbarch *gdbarch)
 {
   struct address_space *aspace;
@@ -479,7 +466,7 @@ get_thread_arch_regcache (ptid_t ptid, struct gdbarch *gdbarch)
 static ptid_t current_thread_ptid;
 static struct gdbarch *current_thread_arch;
 
-struct regcache *
+target_regcache *
 get_thread_regcache (ptid_t ptid)
 {
   if (!current_thread_arch || !ptid_equal (current_thread_ptid, ptid))
@@ -491,7 +478,7 @@ get_thread_regcache (ptid_t ptid)
   return get_thread_arch_regcache (ptid, current_thread_arch);
 }
 
-struct regcache *
+target_regcache *
 get_current_regcache (void)
 {
   return get_thread_regcache (inferior_ptid);
@@ -502,7 +489,7 @@ get_current_regcache (void)
 struct regcache *
 get_thread_regcache_for_ptid (ptid_t ptid)
 {
-  return get_thread_regcache (ptid);
+  return (struct regcache*) get_thread_regcache (ptid);
 }
 
 /* Observer for the target_changed event.  */
@@ -516,9 +503,9 @@ regcache_observer_target_changed (struct target_ops *target)
 /* Update global variables old ptids to hold NEW_PTID if they were
    holding OLD_PTID.  */
 void
-regcache::regcache_thread_ptid_changed (ptid_t old_ptid, ptid_t new_ptid)
+target_regcache::regcache_thread_ptid_changed (ptid_t old_ptid, ptid_t new_ptid)
 {
-  for (auto &regcache : regcache::current_regcache)
+  for (auto &regcache : target_regcache::current_regcache)
     {
       if (ptid_equal (regcache->ptid (), old_ptid))
 	regcache->set_ptid (new_ptid);
@@ -539,15 +526,15 @@ regcache::regcache_thread_ptid_changed (ptid_t old_ptid, ptid_t new_ptid)
 void
 registers_changed_ptid (ptid_t ptid)
 {
-  for (auto oit = regcache::current_regcache.before_begin (),
+  for (auto oit = target_regcache::current_regcache.before_begin (),
 	 it = std::next (oit);
-       it != regcache::current_regcache.end ();
+       it != target_regcache::current_regcache.end ();
        )
     {
       if (ptid_match ((*it)->ptid (), ptid))
 	{
 	  delete *it;
-	  it = regcache::current_regcache.erase_after (oit);
+	  it = target_regcache::current_regcache.erase_after (oit);
 	}
       else
 	oit = it++;
@@ -589,16 +576,14 @@ regcache_raw_update (struct regcache *regcache, int regnum)
 }
 
 void
-regcache::raw_update (int regnum)
+target_regcache::raw_update (int regnum)
 {
   gdb_assert (regnum >= 0 && regnum < m_descr->nr_raw_registers);
 
   /* Make certain that the register cache is up-to-date with respect
-     to the current thread.  This switching shouldn't be necessary
-     only there is still only one target side register cache.  Sigh!
-     On the bright side, at least there is a regcache object.  */
+     to the current thread.  */
 
-  if (!m_readonly_p && get_register_status (regnum) == REG_UNKNOWN)
+  if (get_register_status (regnum) == REG_UNKNOWN)
     {
       target_fetch_registers (this, regnum);
 
@@ -618,17 +603,19 @@ regcache_raw_read (struct regcache *regcache, int regnum, gdb_byte *buf)
 
 enum register_status
 regcache::raw_read (int regnum, gdb_byte *buf)
+{
+  return raw_get_cached_reg (regnum, buf);
+}
+
+enum register_status
+target_regcache::raw_read (int regnum, gdb_byte *buf)
 {
   gdb_assert (buf != NULL);
+
+  /* Read register value from the target into the regcache.  */
   raw_update (regnum);
 
-  if (m_register_status[regnum] != REG_VALID)
-    memset (buf, 0, m_descr->sizeof_register[regnum]);
-  else
-    memcpy (buf, register_buffer (regnum),
-	    m_descr->sizeof_register[regnum]);
-
-  return (enum register_status) m_register_status[regnum];
+  return raw_get_cached_reg (regnum, buf);
 }
 
 enum register_status
@@ -719,8 +706,7 @@ regcache::cooked_read (int regnum, gdb_byte *buf)
   gdb_assert (regnum < m_descr->nr_cooked_registers);
   if (regnum < m_descr->nr_raw_registers)
     return raw_read (regnum, buf);
-  else if (m_readonly_p
-	   && m_register_status[regnum] != REG_UNKNOWN)
+  else if (m_register_status[regnum] != REG_UNKNOWN)
     {
       /* Read-only register cache, perhaps the cooked value was
 	 cached?  */
@@ -772,7 +758,7 @@ regcache::cooked_read_value (int regnum)
   gdb_assert (regnum < m_descr->nr_cooked_registers);
 
   if (regnum < m_descr->nr_raw_registers
-      || (m_readonly_p && m_register_status[regnum] != REG_UNKNOWN)
+      || m_register_status[regnum] != REG_UNKNOWN
       || !gdbarch_pseudo_register_read_value_p (m_descr->gdbarch))
     {
       struct value *result;
@@ -859,21 +845,42 @@ regcache_cooked_write_unsigned (struct regcache *regcache, int regnum,
   regcache->cooked_write (regnum, val);
 }
 
-/* See regcache.h.  */
-
 void
-regcache_raw_set_cached_value (struct regcache *regcache, int regnum,
-			       const gdb_byte *buf)
+regcache::raw_set_cached_reg (int regnum, const gdb_byte *buf)
 {
-  regcache->raw_set_cached_value (regnum, buf);
+  gdb_assert (regnum >= 0 && regnum < m_descr->nr_raw_registers);
+  gdb_assert (!m_readonly_p);
+
+  if (buf)
+    {
+      memcpy (register_buffer (regnum), buf, m_descr->sizeof_register[regnum]);
+      m_register_status[regnum] = REG_VALID;
+    }
+  else
+    {
+      /* This memset not strictly necessary, but better than garbage
+	 in case the register value manages to escape somewhere (due
+	 to a bug, no less).  */
+      memset (register_buffer (regnum), 0, m_descr->sizeof_register[regnum]);
+      m_register_status[regnum] = REG_UNAVAILABLE;
+    }
+
+  gdb_assert (regnum >= 0 && regnum < m_descr->nr_raw_registers);
 }
 
-void
-regcache::raw_set_cached_value (int regnum, const gdb_byte *buf)
+enum register_status
+regcache::raw_get_cached_reg (int regnum, gdb_byte *buf) const
 {
-  memcpy (register_buffer (regnum), buf,
-	  m_descr->sizeof_register[regnum]);
-  m_register_status[regnum] = REG_VALID;
+  gdb_assert (regnum >= 0 && regnum < m_descr->nr_raw_registers);
+  gdb_assert (buf != NULL);
+
+  if (m_register_status[regnum] != REG_VALID)
+    memset (buf, 0, m_descr->sizeof_register[regnum]);
+  else
+    memcpy (buf, register_buffer (regnum),
+	    m_descr->sizeof_register[regnum]);
+
+  return (enum register_status) m_register_status[regnum];
 }
 
 void
@@ -886,12 +893,24 @@ regcache_raw_write (struct regcache *regcache, int regnum,
 
 void
 regcache::raw_write (int regnum, const gdb_byte *buf)
+{
+  gdb_assert (regnum >= 0 && regnum < m_descr->nr_raw_registers);
+
+  /* On the sparc, writing %g0 is a no-op, so we don't even want to
+     change the registers array if something writes to this register.  */
+  if (gdbarch_cannot_store_register (arch (), regnum))
+    return;
+
+  raw_set_cached_reg (regnum, buf);
+}
+
+void
+target_regcache::raw_write (int regnum, const gdb_byte *buf)
 {
   struct cleanup *old_chain;
 
   gdb_assert (buf != NULL);
   gdb_assert (regnum >= 0 && regnum < m_descr->nr_raw_registers);
-  gdb_assert (!m_readonly_p);
 
   /* On the sparc, writing %g0 is a no-op, so we don't even want to
      change the registers array if something writes to this register.  */
@@ -906,7 +925,7 @@ regcache::raw_write (int regnum, const gdb_byte *buf)
     return;
 
   target_prepare_to_store (this);
-  raw_set_cached_value (regnum, buf);
+  raw_set_cached_reg (regnum, buf);
 
   /* Register a cleanup function for invalidating the register after it is
      written, in case of a failure.  */
@@ -1065,28 +1084,7 @@ regcache_raw_supply (struct regcache *regcache, int regnum, const void *buf)
 void
 regcache::raw_supply (int regnum, const void *buf)
 {
-  void *regbuf;
-  size_t size;
-
-  gdb_assert (regnum >= 0 && regnum < m_descr->nr_raw_registers);
-  gdb_assert (!m_readonly_p);
-
-  regbuf = register_buffer (regnum);
-  size = m_descr->sizeof_register[regnum];
-
-  if (buf)
-    {
-      memcpy (regbuf, buf, size);
-      m_register_status[regnum] = REG_VALID;
-    }
-  else
-    {
-      /* This memset not strictly necessary, but better than garbage
-	 in case the register value manages to escape somewhere (due
-	 to a bug, no less).  */
-      memset (regbuf, 0, size);
-      m_register_status[regnum] = REG_UNAVAILABLE;
-    }
+  raw_set_cached_reg (regnum, (const gdb_byte*) buf);
 }
 
 /* Supply register REGNUM to REGCACHE.  Value to supply is an integer stored at
@@ -1146,15 +1144,7 @@ regcache_raw_collect (const struct regcache *regcache, int regnum, void *buf)
 void
 regcache::raw_collect (int regnum, void *buf) const
 {
-  const void *regbuf;
-  size_t size;
-
-  gdb_assert (buf != NULL);
-  gdb_assert (regnum >= 0 && regnum < m_descr->nr_raw_registers);
-
-  regbuf = register_buffer (regnum);
-  size = m_descr->sizeof_register[regnum];
-  memcpy (buf, regbuf, size);
+  raw_get_cached_reg (regnum, (gdb_byte*) buf);
 }
 
 /* Transfer a single or all registers belonging to a certain register
@@ -1668,7 +1658,7 @@ maintenance_print_remote_registers (char *args, int from_tty)
 
 namespace selftests {
 
-class regcache_access : public regcache
+class regcache_access : public target_regcache
 {
 public:
 
@@ -1677,8 +1667,8 @@ public:
   static size_t
   current_regcache_size ()
   {
-    return std::distance (regcache::current_regcache.begin (),
-			  regcache::current_regcache.end ());
+    return std::distance (target_regcache::current_regcache.begin (),
+			  target_regcache::current_regcache.end ());
   }
 };
 
@@ -1692,7 +1682,7 @@ current_regcache_test (void)
 
   /* Get regcache from ptid1, a new regcache is added to
      current_regcache.  */
-  regcache *regcache = get_thread_arch_aspace_regcache (ptid1,
+  target_regcache *regcache = get_thread_arch_aspace_regcache (ptid1,
 							target_gdbarch (),
 							NULL);
 
@@ -1745,7 +1735,8 @@ _initialize_regcache (void)
     = gdbarch_data_register_post_init (init_regcache_descr);
 
   observer_attach_target_changed (regcache_observer_target_changed);
-  observer_attach_thread_ptid_changed (regcache::regcache_thread_ptid_changed);
+  observer_attach_thread_ptid_changed
+    (target_regcache::regcache_thread_ptid_changed);
 
   add_com ("flushregs", class_maintenance, reg_flush_command,
 	   _("Force gdb to flush its register cache (maintainer command)"));

gdb/regcache.h

@@ -24,21 +24,19 @@
 #include <forward_list>
 
 struct regcache;
+class target_regcache;
 struct regset;
 struct gdbarch;
 struct address_space;
 
-extern struct regcache *get_current_regcache (void);
-extern struct regcache *get_thread_regcache (ptid_t ptid);
-extern struct regcache *get_thread_arch_regcache (ptid_t, struct gdbarch *);
-extern struct regcache *get_thread_arch_aspace_regcache (ptid_t,
+extern target_regcache *get_current_regcache (void);
+extern target_regcache *get_thread_regcache (ptid_t ptid);
+extern target_regcache *get_thread_arch_regcache (ptid_t, struct gdbarch *);
+extern target_regcache *get_thread_arch_aspace_regcache (ptid_t,
 							 struct gdbarch *,
 							 struct address_space *);
 
-void regcache_xfree (struct regcache *regcache);
-struct cleanup *make_cleanup_regcache_xfree (struct regcache *regcache);
-struct regcache *regcache_xmalloc (struct gdbarch *gdbarch,
-				   struct address_space *aspace);
+struct cleanup *make_cleanup_regcache_delete (regcache *regcache);
 
 /* Return REGCACHE's ptid.  */
 
@@ -81,14 +79,6 @@ extern void regcache_raw_write_unsigned (struct regcache *regcache,
 extern LONGEST regcache_raw_get_signed (struct regcache *regcache,
 					int regnum);
 
-/* Set a raw register's value in the regcache's buffer.  Unlike
-   regcache_raw_write, this is not write-through.  The intention is
-   allowing to change the buffer contents of a read-only regcache
-   allocated with regcache_xmalloc.  */
-
-extern void regcache_raw_set_cached_value
-  (struct regcache *regcache, int regnum, const gdb_byte *buf);
-
 /* Partial transfer of raw registers.  These perform read, modify,
    write style operations.  The read variant returns the status of the
    register.  */
@@ -211,20 +201,10 @@ extern struct type *register_type (struct gdbarch *gdbarch, int regnum);
    
 extern int register_size (struct gdbarch *gdbarch, int regnum);
 
-
-/* Save/restore a register cache.  The set of registers saved /
-   restored into the DST regcache determined by the save_reggroup /
-   restore_reggroup respectively.  COOKED_READ returns zero iff the
-   register's value can't be returned.  */
-
 typedef enum register_status (regcache_cooked_read_ftype) (void *src,
 							   int regnum,
 							   gdb_byte *buf);
 
-extern void regcache_save (struct regcache *dst,
-			   regcache_cooked_read_ftype *cooked_read,
-			   void *cooked_read_context);
-
 enum regcache_dump_what
 {
   regcache_dump_none, regcache_dump_raw,
@@ -240,30 +220,20 @@ typedef struct cached_reg
   gdb_byte *data;
 } cached_reg_t;
 
-/* The register cache for storing raw register values.  */
+
+/* A register cache.  This is not connected to a target - reads and writes will
+   not be passed through to a target and ptid is unset.  */
 
 class regcache
 {
 public:
-  regcache (gdbarch *gdbarch, address_space *aspace_)
-    : regcache (gdbarch, aspace_, true)
-  {}
-
-  struct readonly_t {};
-  static constexpr readonly_t readonly {};
-
-  /* Create a readonly regcache from a non-readonly regcache.  */
-  regcache (readonly_t, const regcache &src);
+  regcache (gdbarch *gdbarch, address_space *aspace_, bool readonly_p_ = true,
+	    bool allocate_registers = true);
 
   regcache (const regcache &) = delete;
   void operator= (const regcache &) = delete;
 
-  /* class regcache is only extended in unit test, so only mark it
-     virtual when selftest is enabled.  */
-#if GDB_SELF_TEST
-  virtual
-#endif
-  ~regcache ()
+  virtual ~regcache ()
   {
     xfree (m_registers);
     xfree (m_register_status);
@@ -276,19 +246,22 @@ public:
     return m_aspace;
   }
 
+  /* Duplicate self into a new regcache.  */
+  virtual regcache* dup (bool readonly_p = true);
+
+  /* Copy the register contents from a target_regcache to self.
+     All cooked registers are read and cached.  */
   void save (regcache_cooked_read_ftype *cooked_read, void *src);
 
+  /* Copy register contents to a target_regcache. All cached cooked registers
+     are also restored.  */
+  void restore_to (target_regcache *dst);
+
   enum register_status cooked_read (int regnum, gdb_byte *buf);
   void cooked_write (int regnum, const gdb_byte *buf);
 
-  enum register_status raw_read (int regnum, gdb_byte *buf);
-
-  /* class regcache is only extended in unit test, so only mark it
-     virtual when selftest is enabled.  */
-#if GDB_SELF_TEST
-  virtual
-#endif
-  void raw_write (int regnum, const gdb_byte *buf);
+  virtual enum register_status raw_read (int regnum, gdb_byte *buf);
+  virtual void raw_write (int regnum, const gdb_byte *buf);
 
   template<typename T, typename = RequireLongest<T>>
   enum register_status raw_read (int regnum, T *val);
@@ -304,7 +277,7 @@ public:
   template<typename T, typename = RequireLongest<T>>
   void cooked_write (int regnum, T val);
 
-  void raw_update (int regnum);
+  virtual void raw_update (int regnum) {}
 
   void raw_collect (int regnum, void *buf) const;
 
@@ -318,9 +291,7 @@ public:
 
   void raw_supply_zeroed (int regnum);
 
-  enum register_status get_register_status (int regnum) const;
-
-  void raw_set_cached_value (int regnum, const gdb_byte *buf);
+  virtual enum register_status get_register_status (int regnum) const;
 
   void invalidate (int regnum);
 
@@ -344,40 +315,23 @@ public:
 
   void dump (ui_file *file, enum regcache_dump_what what_to_dump);
 
-  ptid_t ptid () const
+  virtual ptid_t ptid () const
   {
-    return m_ptid;
-  }
-
-  void set_ptid (const ptid_t ptid)
-  {
-    this->m_ptid = ptid;
+    /* Ptid of a non-target regcache is always -1.  */
+    return (ptid_t) -1;
   }
 
 /* Dump the contents of a register from the register cache to the target
    debug.  */
   void debug_print_register (const char *func, int regno);
 
-  static void regcache_thread_ptid_changed (ptid_t old_ptid, ptid_t new_ptid);
 protected:
-  regcache (gdbarch *gdbarch, address_space *aspace_, bool readonly_p_);
 
-  static std::forward_list<regcache *> current_regcache;
-
-private:
   gdb_byte *register_buffer (int regnum) const;
 
-  void restore (struct regcache *src);
-
-  enum register_status xfer_part (int regnum, int offset, int len, void *in,
-				  const void *out,
-				  decltype (regcache_raw_read) read,
-				  decltype (regcache_raw_write) write);
-
-  void transfer_regset (const struct regset *regset,
-			struct regcache *out_regcache,
-			int regnum, const void *in_buf,
-			void *out_buf, size_t size) const;
+  /* Get/Set the cached contents of the regcache.  */
+  void raw_set_cached_reg (int regnum, const gdb_byte *buf);
+  enum register_status raw_get_cached_reg (int regnum, gdb_byte *buf) const;
 
   struct regcache_descr *m_descr;
 
@@ -389,37 +343,86 @@ private:
      full [0 .. gdbarch_num_regs + gdbarch_num_pseudo_regs) while a read/write
      register cache can only hold [0 .. gdbarch_num_regs).  */
   gdb_byte *m_registers;
+
   /* Register cache status.  */
   signed char *m_register_status;
-  /* Is this a read-only cache?  A read-only cache is used for saving
-     the target's register state (e.g, across an inferior function
-     call or just before forcing a function return).  A read-only
-     cache can only be updated via the methods regcache_dup() and
-     regcache_cpy().  The actual contents are determined by the
-     reggroup_save and reggroup_restore methods.  */
+
+  /* A read-only cache can not change it's register contents, except from
+     an target_regcache via the save () method.
+     A target_regcache cache can never be read-only.  */
   bool m_readonly_p;
-  /* If this is a read-write cache, which thread's registers is
-     it connected to?  */
-  ptid_t m_ptid;
 
-  friend struct regcache *
-  get_thread_arch_aspace_regcache (ptid_t ptid, struct gdbarch *gdbarch,
-				   struct address_space *aspace);
+private:
 
-  friend void
-  registers_changed_ptid (ptid_t ptid);
+  enum register_status xfer_part (int regnum, int offset, int len, void *in,
+				  const void *out,
+				  decltype (regcache_raw_read) read,
+				  decltype (regcache_raw_write) write);
+
+  void transfer_regset (const struct regset *regset,
+			struct regcache *out_regcache,
+			int regnum, const void *in_buf,
+			void *out_buf, size_t size) const;
+
+private:
 
-  friend void
-  regcache_cpy (struct regcache *dst, struct regcache *src);
 };
 
-/* 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);
 
-/* Writes to DEST will go through to the target.  SRC is a read-only
-   register cache.  */
-extern void regcache_cpy (struct regcache *dest, struct regcache *src);
+/* A register cache attached to a target.  Reads and writes of register values
+   will be passed through to the target and ptid can be set.  */
+
+class target_regcache : public regcache
+{
+public:
+
+  target_regcache (const target_regcache &) = delete;
+  void operator= (const target_regcache &) = delete;
+
+  /* Cannot be called on a target_regcache.  */
+  void save (regcache_cooked_read_ftype *cooked_read, void *src) = delete;
+  void restore_to (target_regcache *dst) = delete;
+
+  /* Duplicate self into a new regcache.  Result is not a target_regcache.  */
+  regcache* dup (bool readonly_p = true);
+
+  /* Overridden regcache methods.  These versions will pass the read/write
+     through to the target.  */
+  enum register_status raw_read (int regnum, gdb_byte *buf);
+  virtual void raw_write (int regnum, const gdb_byte *buf);
+  void raw_update (int regnum);
+  enum register_status get_register_status (int regnum) const;
+
+  ptid_t ptid () const
+  {
+    return m_ptid;
+  }
+
+  static void regcache_thread_ptid_changed (ptid_t old_ptid,
+					    ptid_t new_ptid);
+
+protected:
+
+  /* Constructor is only called via get_thread_arch_aspace_regcache.  */
+  target_regcache (gdbarch *gdbarch, address_space *aspace_);
+
+  void set_ptid (const ptid_t ptid)
+  {
+    this->m_ptid = ptid;
+  }
+
+  static std::forward_list<target_regcache *> current_regcache;
+
+private:
+
+  /* The thread the cache is connected to, or -1 if not attached.  */
+  ptid_t m_ptid;
+
+  friend struct target_regcache * get_thread_arch_aspace_regcache
+    (ptid_t ptid, struct gdbarch *gdbarch, struct address_space *aspace);
+
+  friend void registers_changed_ptid (ptid_t ptid);
+};
 
 extern void registers_changed (void);
 extern void registers_changed_ptid (ptid_t);

gdb/spu-tdep.c

@@ -1275,7 +1275,7 @@ spu2ppu_sniffer (const struct frame_unwind *self,
 	{
 	  struct regcache *regcache;
 	  regcache = get_thread_arch_regcache (inferior_ptid, target_gdbarch ());
-	  cache->regcache = regcache_dup (regcache);
+	  cache->regcache = regcache->dup ();
 	  *this_prologue_cache = cache;
 	  return 1;
 	}
@@ -1288,7 +1288,7 @@ static void
 spu2ppu_dealloc_cache (struct frame_info *self, void *this_cache)
 {
   struct spu2ppu_cache *cache = (struct spu2ppu_cache *) this_cache;
-  regcache_xfree (cache->regcache);
+  delete cache->regcache;
 }
 
 static const struct frame_unwind spu2ppu_unwind = {