File:  [gforth] / gforth / vmgen-ex / peephole.c
Revision 1.7: download - view: text, annotated - select for diffs
Mon Dec 31 19:02:25 2007 UTC (11 years, 10 months ago) by anton
Branches: MAIN
CVS tags: v0-7-0, HEAD
updated copyright year after changing license notice

    1: /* Peephole optimization routines and tables
    2: 
    3:   Copyright (C) 2001,2002,2003,2007 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 3
   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, see http://www.gnu.org/licenses/.
   19: */
   20: 
   21: #include <stdlib.h>
   22: #include "mini.h"
   23: 
   24: /* the numbers in this struct are primitive indices */
   25: typedef struct Combination {
   26:   int prefix;
   27:   int lastprim;
   28:   int combination_prim;
   29: } Combination;
   30: 
   31: Combination peephole_table[] = {
   32: #include "mini-peephole.i"
   33: #ifndef __GNUC__
   34:   {-1,-1,-1} /* unnecessary; just to shut up lcc if the file is empty */
   35: #endif
   36: };
   37: 
   38: int use_super = 1; /* turned off by option -p */
   39: 
   40: typedef struct Peeptable_entry {
   41:   struct Peeptable_entry *next;
   42:   Inst prefix;
   43:   Inst lastprim;
   44:   Inst combination_prim;
   45: } Peeptable_entry;
   46: 
   47: #define HASH_SIZE 1024
   48: #define hash(_i1,_i2) (((((Cell)(_i1))^((Cell)(_i2)))>>4)&(HASH_SIZE-1))
   49: 
   50: Cell peeptable;
   51: 
   52: Cell prepare_peephole_table(Inst insts[])
   53: {
   54:   Cell i;
   55:   Peeptable_entry **pt = (Peeptable_entry **)calloc(HASH_SIZE,sizeof(Peeptable_entry *));
   56: 
   57:   for (i=0; i<sizeof(peephole_table)/sizeof(peephole_table[0]); i++) {
   58:     Combination *c = &peephole_table[i];
   59:     Peeptable_entry *p = (Peeptable_entry *)malloc(sizeof(Peeptable_entry));
   60:     Cell h;
   61:     p->prefix =           insts[c->prefix];
   62:     p->lastprim =         insts[c->lastprim];
   63:     p->combination_prim = insts[c->combination_prim];
   64:     h = hash(p->prefix,p->lastprim);
   65:     p->next = pt[h];
   66:     pt[h] = p;
   67:   }
   68:   return (Cell)pt;
   69: }
   70: 
   71: void init_peeptable(void)
   72: {
   73:   peeptable = prepare_peephole_table(vm_prim);
   74: }
   75: 
   76: Inst peephole_opt(Inst inst1, Inst inst2, Cell peeptable)
   77: {
   78:   Peeptable_entry **pt = (Peeptable_entry **)peeptable;
   79:   Peeptable_entry *p;
   80: 
   81:   if (use_super == 0)
   82:       return 0;
   83:   for (p = pt[hash(inst1,inst2)]; p != NULL; p = p->next)
   84:     if (inst1 == p->prefix && inst2 == p->lastprim)
   85:       return p->combination_prim;
   86:   return NULL;
   87: }
   88: 
   89: Inst *last_compiled = NULL;
   90: 
   91: void gen_inst(Inst **vmcodepp, Inst i)
   92: {
   93:   if (last_compiled != NULL) {
   94:     Inst combo = peephole_opt(*last_compiled, i, peeptable);
   95:     if (combo != NULL) {
   96:       *last_compiled = combo;
   97:       return;
   98:     }
   99:   }
  100:   last_compiled = *vmcodepp;
  101:   **vmcodepp = i;
  102:   (*vmcodepp)++;
  103: }

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