[PATCH v4 02/10] Make gdbserver reg_defs a vector of objects

[alan dot hayward at arm dot com]

From: Alan Hayward <alan.hayward@arm.com>

Following a suggestion from Philipp, this patch changes reg_defs in
gdbserver tdesc so that it is a vector of objects instead of a vector
of pointers. Updated uses of reg_defs to use references.

This change reduces the number of small hunks allocated when building
reg_defs.

find_register_by_number() is only used by regcache, therefore I made
it a static function and moved it earlier in the file so that find_regno()
could use it. The eventual plan is to replace this with accessor functions
in a common tdesc class.

Alan.

2018-03-21  Alan Hayward  <alan.hayward@arm.com>

gdb/gdbserver/
	* regcache.c (find_register_by_number): Make static and return a ref.
	(find_regno): Use find_register_by_number
	(register_size): Use references.
	(register_data): Likewise.
	* regcache.h (struct reg): Remove declaration.
	* tdesc.c (target_desc::~target_desc): Remove free calls.
	(target_desc::operator==): Use references.
	(init_target_desc): Likewise.
	(tdesc_create_reg): Use references and resize in a single call.
	* tdesc.h (struct target_desc): Replace pointer with object.
---
 gdb/gdbserver/regcache.c | 27 +++++++++++----------------
 gdb/gdbserver/regcache.h |  4 ----
 gdb/gdbserver/tdesc.c    | 30 ++++++++++++++----------------
 gdb/gdbserver/tdesc.h    |  2 +-
 4 files changed, 26 insertions(+), 37 deletions(-)

diff --git a/gdb/gdbserver/regcache.c b/gdb/gdbserver/regcache.c
index 1bb15900dd..df5b9e9dd2 100644
--- a/gdb/gdbserver/regcache.c
+++ b/gdb/gdbserver/regcache.c
@@ -196,6 +196,13 @@ regcache_cpy (struct regcache *dst, struct regcache *src)
   dst->registers_valid = src->registers_valid;
 }
 
+/* Return a reference to the description of register ``n''.  */
+
+static const struct reg &
+find_register_by_number (const struct target_desc *tdesc, int n)
+{
+  return tdesc->reg_defs[n];
+}
 
 #ifndef IN_PROCESS_AGENT
 
@@ -243,25 +250,13 @@ int
 find_regno (const struct target_desc *tdesc, const char *name)
 {
   for (int i = 0; i < tdesc->reg_defs.size (); ++i)
-    {
-      struct reg *reg = tdesc->reg_defs[i];
+    if (strcmp (name, find_register_by_number (tdesc, i).name) == 0)
+      return i;
 
-      if (strcmp (name, reg->name) == 0)
-	return i;
-    }
   internal_error (__FILE__, __LINE__, "Unknown register %s requested",
 		  name);
 }
 
-#endif
-
-struct reg *
-find_register_by_number (const struct target_desc *tdesc, int n)
-{
-  return tdesc->reg_defs[n];
-}
-
-#ifndef IN_PROCESS_AGENT
 static void
 free_register_cache_thread (struct thread_info *thread)
 {
@@ -292,7 +287,7 @@ register_cache_size (const struct target_desc *tdesc)
 int
 register_size (const struct target_desc *tdesc, int n)
 {
-  return find_register_by_number (tdesc, n)->size / 8;
+  return find_register_by_number (tdesc, n).size / 8;
 }
 
 /* See common/common-regcache.h.  */
@@ -307,7 +302,7 @@ static unsigned char *
 register_data (struct regcache *regcache, int n, int fetch)
 {
   return (regcache->registers
-	  + find_register_by_number (regcache->tdesc, n)->offset / 8);
+	  + find_register_by_number (regcache->tdesc, n).offset / 8);
 }
 
 /* Supply register N, whose contents are stored in BUF, to REGCACHE.
diff --git a/gdb/gdbserver/regcache.h b/gdb/gdbserver/regcache.h
index 3a75ce3fe1..6ff13084b0 100644
--- a/gdb/gdbserver/regcache.h
+++ b/gdb/gdbserver/regcache.h
@@ -94,10 +94,6 @@ void registers_from_string (struct regcache *regcache, char *buf);
 
 void regcache_write_pc (struct regcache *regcache, CORE_ADDR pc);
 
-/* Return a pointer to the description of register ``n''.  */
-
-struct reg *find_register_by_number (const struct target_desc *tdesc, int n);
-
 int register_cache_size (const struct target_desc *tdesc);
 
 int register_size (const struct target_desc *tdesc, int n);
diff --git a/gdb/gdbserver/tdesc.c b/gdb/gdbserver/tdesc.c
index e50a848e2f..8e68a27c7c 100644
--- a/gdb/gdbserver/tdesc.c
+++ b/gdb/gdbserver/tdesc.c
@@ -25,9 +25,6 @@ target_desc::~target_desc ()
 {
   int i;
 
-  for (reg *reg : reg_defs)
-    xfree (reg);
-
   xfree ((char *) arch);
   xfree ((char *) osabi);
 
@@ -45,10 +42,10 @@ bool target_desc::operator== (const target_desc &other) const
 
   for (int i = 0; i < reg_defs.size (); ++i)
     {
-      struct reg *reg = reg_defs[i];
-      struct reg *reg2 = other.reg_defs[i];
+      struct reg reg = reg_defs[i];
+      struct reg reg2 = other.reg_defs[i];
 
-      if (reg != reg2 && *reg != *reg2)
+      if (&reg != &reg2 && reg != reg2)
 	return false;
     }
 
@@ -72,10 +69,10 @@ init_target_desc (struct target_desc *tdesc)
 {
   int offset = 0;
 
-  for (reg *reg : tdesc->reg_defs)
+  for (reg &reg : tdesc->reg_defs)
     {
-      reg->offset = offset;
-      offset += reg->size;
+      reg.offset = offset;
+      offset += reg.size;
     }
 
   tdesc->registers_size = offset / 8;
@@ -240,24 +237,25 @@ tdesc_create_reg (struct tdesc_feature *feature, const char *name,
 		  int bitsize, const char *type)
 {
   struct target_desc *tdesc = (struct target_desc *) feature;
+  int current_size = tdesc->reg_defs.size ();
 
-  while (tdesc->reg_defs.size () < regnum)
-    {
-      struct reg *reg = XCNEW (struct reg);
+  tdesc->reg_defs.resize (regnum != 0 ? regnum + 1 : current_size + 1);
 
+  while (current_size < regnum)
+    {
+      struct reg *reg = &tdesc->reg_defs[current_size];
       reg->name = "";
       reg->size = 0;
-      tdesc->reg_defs.push_back (reg);
+      current_size++;
     }
 
   gdb_assert (regnum == 0
-	      || regnum == tdesc->reg_defs.size ());
+	      || regnum + 1 == tdesc->reg_defs.size ());
 
-  struct reg *reg = XCNEW (struct reg);
+  struct reg *reg = &tdesc->reg_defs.back ();
 
   reg->name = name;
   reg->size = bitsize;
-  tdesc->reg_defs.push_back (reg);
 }
 
 /* See common/tdesc.h.  */
diff --git a/gdb/gdbserver/tdesc.h b/gdb/gdbserver/tdesc.h
index 4513ea7423..a62544341c 100644
--- a/gdb/gdbserver/tdesc.h
+++ b/gdb/gdbserver/tdesc.h
@@ -34,7 +34,7 @@ struct target_desc : tdesc_feature
 {
   /* A vector of elements of register definitions that
      describe the inferior's register set.  */
-  std::vector<struct reg *> reg_defs;
+  std::vector<struct reg> reg_defs;
 
   /* The register cache size, in bytes.  */
   int registers_size;
-- 
2.14.3 (Apple Git-98)