WL#2001: Optimize stored procedure code.

Added a simple optimizer that shortcuts jumps and skip unused instructions.


sql/sp.cc:
  Optimize the code after parsing.
sql/sp_head.cc:
  Added a simple optimizer that shortcuts jumps and skip unused instructions.
sql/sp_head.h:
  Added a simple optimizer that shortcuts jumps and skip unused instructions.

sql/sp.cc

@@ -292,6 +292,7 @@ db_find_routine(THD *thd, int type, sp_name *name, sp_head **sphp)
       *sphp= thd->lex->sphead;
       (*sphp)->set_info((char *)definer, (uint)strlen(definer),
 			created, modified, &chistics, sql_mode);
+      (*sphp)->optimize();
     }
     thd->lex->sql_command= oldcmd;
     thd->variables.sql_mode= old_sql_mode;

sql/sp_head.cc

@@ -317,22 +317,26 @@ sp_head::create(THD *thd)
 
   DBUG_PRINT("info", ("type: %d name: %s params: %s body: %s",
 		      m_type, m_name.str, m_params.str, m_body.str));
+
 #ifndef DBUG_OFF
-  String s;
-  sp_instr *i;
-  uint ip= 0;
-  while ((i = get_instr(ip)))
+  optimize();
   {
-    char buf[8];
+    String s;
+    sp_instr *i;
+    uint ip= 0;
+    while ((i = get_instr(ip)))
+    {
+      char buf[8];
 
-    sprintf(buf, "%4u: ", ip);
-    s.append(buf);
-    i->print(&s);
-    s.append('\n');
-    ip+= 1;
+      sprintf(buf, "%4u: ", ip);
+      s.append(buf);
+      i->print(&s);
+      s.append('\n');
+      ip+= 1;
+    }
+    s.append('\0');
+    DBUG_PRINT("info", ("Code %s\n%s", m_qname.str, s.ptr()));
   }
-  s.append('\0');
-  DBUG_PRINT("info", ("Code %s\n%s", m_qname.str, s.ptr()));
 #endif
 
   if (m_type == TYPE_ENUM_FUNCTION)
@@ -981,6 +985,58 @@ sp_head::show_create_function(THD *thd)
   thd->variables.sql_mode= old_sql_mode;
   DBUG_RETURN(res);
 }
+
+void
+sp_head::optimize()
+{
+  List<sp_instr> bp;
+  sp_instr *i;
+  uint src, dst;
+
+  opt_mark(0);
+
+  bp.empty();
+  src= dst= 0;
+  while ((i= get_instr(src)))
+  {
+    if (! i->marked)
+    {
+      delete i;
+      src+= 1;
+    }
+    else
+    {
+      if (src != dst)
+      {
+	sp_instr *ibp;
+	List_iterator_fast<sp_instr> li(bp);
+
+	set_dynamic(&m_instr, (gptr)&i, dst);
+	while ((ibp= li++))
+	{
+	  sp_instr_jump *ji= static_cast<sp_instr_jump *>(ibp);
+	  if (ji->m_dest == src)
+	    ji->m_dest= dst;
+	}
+      }
+      i->opt_move(dst, &bp);
+      src+= 1;
+      dst+= 1;
+    }
+  }
+  m_instr.elements= dst;
+  bp.empty();
+}
+
+void
+sp_head::opt_mark(uint ip)
+{
+  sp_instr *i;
+
+  while ((i= get_instr(ip)) && !i->marked)
+    ip= i->opt_mark(this);
+}
+
 // ------------------------------------------------------------------
 
 //
@@ -1091,6 +1147,42 @@ sp_instr_jump::print(String *str)
   str->qs_append(m_dest);
 }
 
+uint
+sp_instr_jump::opt_mark(sp_head *sp)
+{
+  marked= 1;
+  m_dest= opt_shortcut_jump(sp);
+  m_optdest= sp->get_instr(m_dest);
+  return m_dest;
+}
+
+uint
+sp_instr_jump::opt_shortcut_jump(sp_head *sp)
+{
+  uint dest= m_dest;
+  sp_instr *i;
+
+  while ((i= sp->get_instr(dest)))
+  {
+    uint ndest= i->opt_shortcut_jump(sp);
+
+    if (ndest == dest)
+      break;
+    dest= ndest;
+  }
+  return dest;
+}
+
+void
+sp_instr_jump::opt_move(uint dst, List<sp_instr> *bp)
+{
+  if (m_dest > m_ip)
+    bp->push_back(this);	// Forward
+  else if (m_optdest)
+    m_dest= m_optdest->m_ip;	// Backward
+  m_ip= dst;
+}
+
 //
 // sp_instr_jump_if
 //
@@ -1120,6 +1212,21 @@ sp_instr_jump_if::print(String *str)
   m_expr->print(str);
 }
 
+uint
+sp_instr_jump_if::opt_mark(sp_head *sp)
+{
+  sp_instr *i;
+
+  marked= 1;
+  if ((i= sp->get_instr(m_dest)))
+  {
+    m_dest= i->opt_shortcut_jump(sp);
+    m_optdest= sp->get_instr(m_dest);
+  }
+  sp->opt_mark(m_dest);
+  return m_ip+1;
+}
+
 //
 // sp_instr_jump_if_not
 //
@@ -1149,6 +1256,21 @@ sp_instr_jump_if_not::print(String *str)
   m_expr->print(str);
 }
 
+uint
+sp_instr_jump_if_not::opt_mark(sp_head *sp)
+{
+  sp_instr *i;
+
+  marked= 1;
+  if ((i= sp->get_instr(m_dest)))
+  {
+    m_dest= i->opt_shortcut_jump(sp);
+    m_optdest= sp->get_instr(m_dest);
+  }
+  sp->opt_mark(m_dest);
+  return m_ip+1;
+}
+
 //
 // sp_instr_freturn
 //
@@ -1206,6 +1328,21 @@ sp_instr_hpush_jump::print(String *str)
   str->qs_append(m_handler);
 }
 
+uint
+sp_instr_hpush_jump::opt_mark(sp_head *sp)
+{
+  sp_instr *i;
+
+  marked= 1;
+  if ((i= sp->get_instr(m_dest)))
+  {
+    m_dest= i->opt_shortcut_jump(sp);
+    m_optdest= sp->get_instr(m_dest);
+  }
+  sp->opt_mark(m_dest);
+  return m_ip+1;
+}
+
 //
 // sp_instr_hpop
 //

sql/sp_head.h

@@ -201,6 +201,20 @@ class sp_head :private Item_arena
 
   void restore_thd_mem_root(THD *thd);
 
+  void optimize();
+  void opt_mark(uint ip);
+
+  inline sp_instr *
+  get_instr(uint i)
+  {
+    sp_instr *ip;
+
+    if (i < m_instr.elements)
+      get_dynamic(&m_instr, (gptr)&ip, i);
+    else
+      ip= NULL;
+    return ip;
+  }
 
 private:
 
@@ -218,18 +232,6 @@ class sp_head :private Item_arena
   } bp_t;
   List<bp_t> m_backpatch;	// Instructions needing backpatching
 
-  inline sp_instr *
-  get_instr(uint i)
-  {
-    sp_instr *ip;
-
-    if (i < m_instr.elements)
-      get_dynamic(&m_instr, (gptr)&ip, i);
-    else
-      ip= NULL;
-    return ip;
-  }
-
   int
   execute(THD *thd);
 
@@ -247,11 +249,13 @@ class sp_instr : public Sql_alloc
 
 public:
 
+  uint marked;
   Item *free_list;              // My Items
+  uint m_ip;			// My index
 
   // Should give each a name or type code for debugging purposes?
   sp_instr(uint ip)
-    :Sql_alloc(), free_list(0), m_ip(ip)
+    :Sql_alloc(), marked(0), free_list(0), m_ip(ip)
   {}
 
   virtual ~sp_instr()
@@ -265,9 +269,24 @@ class sp_instr : public Sql_alloc
 
   virtual void print(String *str) = 0;
 
-protected:
+  virtual void set_destination(uint dest)
+  {}
 
-  uint m_ip;			// My index
+  virtual uint opt_mark(sp_head *sp)
+  {
+    marked= 1;
+    return m_ip+1;
+  }
+
+  virtual uint opt_shortcut_jump(sp_head *sp)
+  {
+    return m_ip;
+  }
+
+  virtual void opt_move(uint dst, List<sp_instr> *ibp)
+  {
+    m_ip= dst;
+  }
 
 }; // class sp_instr : public Sql_alloc
 
@@ -349,12 +368,14 @@ class sp_instr_jump : public sp_instr
 
 public:
 
+  uint m_dest;			// Where we will go
+
   sp_instr_jump(uint ip)
-    : sp_instr(ip), m_dest(0)
+    : sp_instr(ip), m_dest(0), m_optdest(0)
   {}
 
   sp_instr_jump(uint ip, uint dest)
-    : sp_instr(ip), m_dest(dest)
+    : sp_instr(ip), m_dest(dest), m_optdest(0)
   {}
 
   virtual ~sp_instr_jump()
@@ -364,6 +385,12 @@ class sp_instr_jump : public sp_instr
 
   virtual void print(String *str);
 
+  virtual uint opt_mark(sp_head *sp);
+
+  virtual uint opt_shortcut_jump(sp_head *sp);
+
+  virtual void opt_move(uint dst, List<sp_instr> *ibp);
+
   virtual void
   set_destination(uint dest)
   {
@@ -373,7 +400,7 @@ class sp_instr_jump : public sp_instr
 
 protected:
 
-  int m_dest;			// Where we will go
+  sp_instr *m_optdest;		// Used during optimization
 
 }; // class sp_instr_jump : public sp_instr
 
@@ -400,6 +427,13 @@ class sp_instr_jump_if : public sp_instr_jump
 
   virtual void print(String *str);
 
+  virtual uint opt_mark(sp_head *sp);
+
+  virtual uint opt_shortcut_jump(sp_head *sp)
+  {
+    return m_ip;
+  }
+
 private:
 
   Item *m_expr;			// The condition
@@ -429,6 +463,13 @@ class sp_instr_jump_if_not : public sp_instr_jump
 
   virtual void print(String *str);
 
+  virtual uint opt_mark(sp_head *sp);
+
+  virtual uint opt_shortcut_jump(sp_head *sp)
+  {
+    return m_ip;
+  }
+
 private:
 
   Item *m_expr;			// The condition
@@ -454,6 +495,12 @@ class sp_instr_freturn : public sp_instr
 
   virtual void print(String *str);
 
+  virtual uint opt_mark(sp_head *sp)
+  {
+    marked= 1;
+    return UINT_MAX;
+  }
+
 protected:
 
   Item *m_value;
@@ -485,6 +532,13 @@ class sp_instr_hpush_jump : public sp_instr_jump
 
   virtual void print(String *str);
 
+  virtual uint opt_mark(sp_head *sp);
+
+  virtual uint opt_shortcut_jump(sp_head *sp)
+  {
+    return m_ip;
+  }
+
   inline void add_condition(struct sp_cond_type *cond)
   {
     m_cond.push_front(cond);
@@ -543,6 +597,12 @@ class sp_instr_hreturn : public sp_instr
 
   virtual void print(String *str);
 
+  virtual uint opt_mark(sp_head *sp)
+  {
+    marked= 1;
+    return UINT_MAX;
+  }
+
 private:
 
   uint m_frame;
@@ -700,6 +760,12 @@ class sp_instr_error : public sp_instr
 
   virtual void print(String *str);
 
+  virtual uint opt_mark(sp_head *sp)
+  {
+    marked= 1;
+    return UINT_MAX;
+  }
+
 private:
 
   int m_errcode;