src/luac/opt.c

   1 /*
   2 ** $Id: opt.c,v 1.22 2000/10/31 16:57:23 lhf Exp $
   3 ** optimize bytecodes
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10
  11 #include "luac.h"
  12
  13 static int MapConstant(Hash* t, int j, const TObject* key)
  14 {
  15  const TObject* o=luaH_get(L,t,key);
  16  if (ttype(o)==LUA_TNUMBER)
  17   return (int) nvalue(o);
  18  else
  19  {
  20   TObject val;
  21   ttype(&val)=LUA_TNUMBER;
  22   nvalue(&val)=j;
  23   *luaH_set(L,t,key)=val;
  24   LUA_ASSERT(j>=0,"MapConstant returns negative!");
  25   return j;
  26  }
  27 }
  28
  29 static int MapConstants(Proto* tf, Hash* map)
  30 {
  31  int i,j,k,n,m=0;
  32  TObject o;
  33  j=0; n=tf->nknum; ttype(&o)=LUA_TNUMBER;
  34  for (i=0; i<n; i++)
  35  {
  36   nvalue(&o)=tf->knum[i];
  37   k=MapConstant(map,j,&o);
  38   if (k==j) j++;
  39  }
  40  m=j;
  41  j=0; n=tf->nkstr; ttype(&o)=LUA_TSTRING;
  42  for (i=0; i<n; i++)
  43  {
  44   tsvalue(&o)=tf->kstr[i];
  45   k=MapConstant(map,j,&o);
  46   if (k==j) j++;
  47  }
  48  return m+j;
  49 }
  50
  51 static void PackConstants(Proto* tf, Hash* map)
  52 {
  53  int i,j,k,n;
  54  TObject o;
  55 #ifdef DEBUG
  56  printf("%p before pack nknum=%d nkstr=%d\n",tf,tf->nknum,tf->nkstr);
  57 #endif
  58  j=0; n=tf->nknum; ttype(&o)=LUA_TNUMBER;
  59  for (i=0; i<n; i++)
  60  {
  61   nvalue(&o)=tf->knum[i];
  62   k=MapConstant(map,-1,&o);
  63   if (k==j) tf->knum[j++]=tf->knum[i];
  64  }
  65  tf->nknum=j;
  66  j=0; n=tf->nkstr; ttype(&o)=LUA_TSTRING;
  67  for (i=0; i<n; i++)
  68  {
  69   tsvalue(&o)=tf->kstr[i];
  70   k=MapConstant(map,-1,&o);
  71   if (k==j) tf->kstr[j++]=tf->kstr[i];
  72  }
  73  tf->nkstr=j;
  74 #ifdef DEBUG
  75  printf("%p after  pack nknum=%d nkstr=%d\n",tf,tf->nknum,tf->nkstr);
  76 #endif
  77 }
  78
  79 static void OptConstants(Proto* tf)
  80 {
  81  Instruction* p;
  82  int n=tf->nknum+tf->nkstr;
  83  Hash* map=luaH_new(L,n);
  84  int m=MapConstants(tf,map);
  85 #ifdef DEBUG
  86  printf("%p n=%d m=%d %s\n",tf,n,m,(m==n)?"nothing to optimize":"yes!");
  87 #endif
  88  if (m==n) return;
  89  for (p=tf->code;; p++)
  90  {
  91   Instruction i=*p;
  92   int op=GET_OPCODE(i);
  93   switch (op)
  94   {
  95    TObject o;
  96    int j,k;
  97    case OP_PUSHNUM: case OP_PUSHNEGNUM:
  98     j=GETARG_U(i);
  99     ttype(&o)=LUA_TNUMBER; nvalue(&o)=tf->knum[j];
 100     k=MapConstant(map,-1,&o);
 101     if (k!=j) *p=CREATE_U(op,k);
 102     break;
 103    case OP_PUSHSTRING: case OP_GETGLOBAL: case OP_GETDOTTED:
 104    case OP_PUSHSELF:   case OP_SETGLOBAL:
 105     j=GETARG_U(i);
 106     ttype(&o)=LUA_TSTRING; tsvalue(&o)=tf->kstr[j];
 107     k=MapConstant(map,-1,&o);
 108     if (k!=j) *p=CREATE_U(op,k);
 109     break;
 110    case OP_END:
 111     PackConstants(tf,map);
 112     luaH_free(L,map);
 113     return;
 114    default:
 115     break;
 116   }
 117  }
 118 }
 119
 120 #define OptFunction luaU_optchunk
 121
 122 void OptFunction(Proto* tf)
 123 {
 124  int i,n=tf->nkproto;
 125  OptConstants(tf);
 126  for (i=0; i<n; i++) OptFunction(tf->kproto[i]);
 127 }