File:  [gforth] / gforth / vmgen-ex / peephole.c
Revision 1.4: download - view: text, annotated - select for diffs
Sun Mar 9 15:17:09 2003 UTC (17 years, 1 month ago) by anton
Branches: MAIN
CVS tags: v0-6-1, v0-6-0, HEAD
updated copyright years

    1: /* Peephole optimization routines and tables
    2: 
    3:   Copyright (C) 2001,2002 Free Software Foundation, Inc.
    4: 
    5:   This file is part of Gforth.
    6: 
    7:   Gforth is free software; you can redistribute it and/or
    8:   modify it under the terms of the GNU General Public License
    9:   as published by the Free Software Foundation; either version 2
   10:   of the License, or (at your option) any later version.
   11: 
   12:   This program is distributed in the hope that it will be useful,
   13:   but WITHOUT ANY WARRANTY; without even the implied warranty of
   14:   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   15:   GNU General Public License for more details.
   16: 
   17:   You should have received a copy of the GNU General Public License
   18:   along with this program; if not, write to the Free Software
   19:   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
   20: */
   21: 
   22: #include <stdlib.h>
   23: #include "mini.h"
   24: 
   25: /* the numbers in this struct are primitive indices */
   26: typedef struct Combination {
   27:   int prefix;
   28:   int lastprim;
   29:   int combination_prim;
   30: } Combination;
   31: 
   32: Combination peephole_table[] = {
   33: #include "mini-peephole.i"
   34: #ifndef __GNUC__
   35:   {-1,-1,-1} /* unnecessary; just to shut up lcc if the file is empty */
   36: #endif
   37: };
   38: 
   39: int use_super = 1; /* turned off by option -p */
   40: 
   41: typedef struct Peeptable_entry {
   42:   struct Peeptable_entry *next;
   43:   Inst prefix;
   44:   Inst lastprim;
   45:   Inst combination_prim;
   46: } Peeptable_entry;
   47: 
   48: #define HASH_SIZE 1024
   49: #define hash(_i1,_i2) (((((Cell)(_i1))^((Cell)(_i2)))>>4)&(HASH_SIZE-1))
   50: 
   51: Cell peeptable;
   52: 
   53: Cell prepare_peephole_table(Inst insts[])
   54: {
   55:   Cell i;
   56:   Peeptable_entry **pt = (Peeptable_entry **)calloc(HASH_SIZE,sizeof(Peeptable_entry *));
   57: 
   58:   for (i=0; i<sizeof(peephole_table)/sizeof(peephole_table[0]); i++) {
   59:     Combination *c = &peephole_table[i];
   60:     Peeptable_entry *p = (Peeptable_entry *)malloc(sizeof(Peeptable_entry));
   61:     Cell h;
   62:     p->prefix =           insts[c->prefix];
   63:     p->lastprim =         insts[c->lastprim];
   64:     p->combination_prim = insts[c->combination_prim];
   65:     h = hash(p->prefix,p->lastprim);
   66:     p->next = pt[h];
   67:     pt[h] = p;
   68:   }
   69:   return (Cell)pt;
   70: }
   71: 
   72: void init_peeptable(void)
   73: {
   74:   peeptable = prepare_peephole_table(vm_prim);
   75: }
   76: 
   77: Inst peephole_opt(Inst inst1, Inst inst2, Cell peeptable)
   78: {
   79:   Peeptable_entry **pt = (Peeptable_entry **)peeptable;
   80:   Peeptable_entry *p;
   81: 
   82:   if (use_super == 0)
   83:       return 0;
   84:   for (p = pt[hash(inst1,inst2)]; p != NULL; p = p->next)
   85:     if (inst1 == p->prefix && inst2 == p->lastprim)
   86:       return p->combination_prim;
   87:   return NULL;
   88: }
   89: 
   90: Inst *last_compiled = NULL;
   91: 
   92: void gen_inst(Inst **vmcodepp, Inst i)
   93: {
   94:   if (last_compiled != NULL) {
   95:     Inst combo = peephole_opt(*last_compiled, i, peeptable);
   96:     if (combo != NULL) {
   97:       *last_compiled = combo;
   98:       return;
   99:     }
  100:   }
  101:   last_compiled = *vmcodepp;
  102:   **vmcodepp = i;
  103:   (*vmcodepp)++;
  104: }

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