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/* Peephole optimization routines and tables
Copyright (C) 2001,2002,2003,2007 Free Software Foundation, Inc.
This file is part of Gforth.
Gforth is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation, either version 3
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, see http://www.gnu.org/licenses/.
*/
#include <stdlib.h>
#include "mini.h"
/* the numbers in this struct are primitive indices */
typedef struct Combination {
int prefix;
int lastprim;
int combination_prim;
} Combination;
Combination peephole_table[] = {
#include "mini-peephole.i"
#ifndef __GNUC__
{-1,-1,-1} /* unnecessary; just to shut up lcc if the file is empty */
#endif
};
int use_super = 1; /* turned off by option -p */
typedef struct Peeptable_entry {
struct Peeptable_entry *next;
Label prefix;
Label lastprim;
Label combination_prim;
} Peeptable_entry;
#define HASH_SIZE 1024
#define hash(_i1,_i2) (((((long)(_i1))^((long)(_i2)))>>4)&(HASH_SIZE-1))
struct Peeptable_entry **peeptable;
Peeptable_entry **prepare_peephole_table(Label insts[])
{
long i;
Peeptable_entry **pt = (Peeptable_entry **)calloc(HASH_SIZE,sizeof(Peeptable_entry *));
for (i=0; i<sizeof(peephole_table)/sizeof(peephole_table[0]); i++) {
Combination *c = &peephole_table[i];
Peeptable_entry *p = (Peeptable_entry *)malloc(sizeof(Peeptable_entry));
long h;
p->prefix = insts[c->prefix];
p->lastprim = insts[c->lastprim];
p->combination_prim = insts[c->combination_prim];
h = hash((p->prefix),(p->lastprim));
p->next = pt[h];
pt[h] = p;
}
return pt;
}
void init_peeptable(void)
{
peeptable = prepare_peephole_table(vm_prim);
}
Label peephole_opt(Label inst1, Label inst2, Peeptable_entry **peeptable)
{
Peeptable_entry **pt = (Peeptable_entry **)peeptable;
Peeptable_entry *p;
if (use_super == 0)
return NULL;
for (p = pt[hash(inst1,inst2)]; p != NULL; p = p->next)
if (inst1 == p->prefix && inst2 == p->lastprim)
return p->combination_prim;
return NULL;
}
Inst *last_compiled = NULL;
void gen_inst(Inst **vmcodepp, Label i)
{
if (last_compiled != NULL) {
Label combo = peephole_opt((*last_compiled).inst, i, peeptable);
if (combo != NULL) {
(*last_compiled).inst = combo;
return;
}
}
last_compiled = *vmcodepp;
(**vmcodepp).inst = i;
(*vmcodepp)++;
}
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