Annotation of gforth/vmgen-ex2/peephole.c, revision 1.1

1.1     ! anton       1: /* Peephole optimization routines and tables
        !             2: 
        !             3:   Copyright (C) 2001 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: };
        !            35: 
        !            36: int use_super = 1;
        !            37: 
        !            38: typedef struct Peeptable_entry {
        !            39:   struct Peeptable_entry *next;
        !            40:   Label prefix;
        !            41:   Label lastprim;
        !            42:   Label combination_prim;
        !            43: } Peeptable_entry;
        !            44: 
        !            45: #define HASH_SIZE 1024
        !            46: #define hash(_i1,_i2) (((((long)(_i1))^((long)(_i2)))>>4)&(HASH_SIZE-1))
        !            47: 
        !            48: struct Peeptable_entry **peeptable;
        !            49: 
        !            50: Peeptable_entry **prepare_peephole_table(Label insts[])
        !            51: {
        !            52:   long i;
        !            53:   Peeptable_entry **pt = (Peeptable_entry **)calloc(HASH_SIZE,sizeof(Peeptable_entry *));
        !            54: 
        !            55:   for (i=0; i<sizeof(peephole_table)/sizeof(peephole_table[0]); i++) {
        !            56:     Combination *c = &peephole_table[i];
        !            57:     Peeptable_entry *p = (Peeptable_entry *)malloc(sizeof(Peeptable_entry));
        !            58:     long h;
        !            59:     p->prefix =           insts[c->prefix];
        !            60:     p->lastprim =         insts[c->lastprim];
        !            61:     p->combination_prim = insts[c->combination_prim];
        !            62:     h = hash((p->prefix),(p->lastprim));
        !            63:     p->next = pt[h];
        !            64:     pt[h] = p;
        !            65:   }
        !            66:   return pt;
        !            67: }
        !            68: 
        !            69: void init_peeptable(void)
        !            70: {
        !            71:   peeptable = prepare_peephole_table(vm_prim);
        !            72: }
        !            73: 
        !            74: Label peephole_opt(Label inst1, Label inst2, Peeptable_entry **peeptable)
        !            75: {
        !            76:   Peeptable_entry **pt = (Peeptable_entry **)peeptable;
        !            77:   Peeptable_entry *p;
        !            78: 
        !            79:   if (use_super == 0)
        !            80:       return NULL;
        !            81:   for (p = pt[hash(inst1,inst2)]; p != NULL; p = p->next)
        !            82:     if (inst1 == p->prefix && inst2 == p->lastprim)
        !            83:       return p->combination_prim;
        !            84:   return NULL;
        !            85: }
        !            86: 
        !            87: Inst *last_compiled = NULL;
        !            88: 
        !            89: void gen_inst(Inst **vmcodepp, Label i)
        !            90: {
        !            91:   if (last_compiled != NULL) {
        !            92:     Label combo = peephole_opt((*last_compiled).inst, i, peeptable);
        !            93:     if (combo != NULL) {
        !            94:       (*last_compiled).inst = combo;
        !            95:       return;
        !            96:     }
        !            97:   }
        !            98:   last_compiled = *vmcodepp;
        !            99:   (**vmcodepp).inst = i;
        !           100:   (*vmcodepp)++;
        !           101: }

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