sample4.brg

%{
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
enum {
	ADDI=309, ADDRLP=295, ASGNI=53,
	CNSTI=21, CVCI=85, I0I=661, INDIRC=67
};

#define STATE_TYPE long
typedef struct tree {
	int op;
	struct tree *kids[2];
	int val;
	struct { STATE_TYPE state; } x;
} *NODEPTR_TYPE, *Tree;
#define LEFT_CHILD(p) ((p)->kids[0])
#define RIGHT_CHILD(p) ((p)->kids[1])
#define PANIC printf
#define STATE_LABEL(p) ((p)->x.state)

int OP_LABEL(NODEPTR_TYPE p) {
	switch (p->op) {
	case CNSTI:  if (p->val == 0) return 661 /* I0I */;
	default:     return p->op;
	}
}

static void burm_trace(NODEPTR_TYPE, int, int, int);
%}
%term ADDI=309 ADDRLP=295 ASGNI=53
%term CNSTI=21 CVCI=85 I0I=661 INDIRC=67
%%
stmt:	ASGNI(disp,reg) = 4 (1);
stmt:	reg = 5;
reg:	ADDI(reg,rc) = 6 (1);
reg:	CVCI(INDIRC(disp)) = 7 (1);
reg:	I0I = 8;
reg:	disp = 9 (1);
disp:	ADDI(reg,con) = 10;
disp:	ADDRLP = 11;
rc:	con = 12;
rc:	reg = 13;
con:	CNSTI = 14;
con:	I0I = 15;
%%

static int trace;

/* burm_trace - print trace message for matching p; decrement trace */
static void burm_trace(NODEPTR_TYPE p, int eruleno, int cost, int bestcost) {
	if (trace < 0)
		fprintf(stderr, "0x%p matched %s = %d with cost %d vs. %d\n", p,
			burm_string[eruleno], eruleno, cost, bestcost);
	else if (trace > 0 && cost < bestcost) {
		--trace;
		fprintf(stderr, "0x%p matched %s = %d with cost %d\n", p,
			burm_string[eruleno], eruleno, cost);
	}
}

/* dumpCover - print the matched cover for p */
static void dumpCover(Tree p, int goalnt, int indent) {
	int eruleno = burm_rule(p->x.state, goalnt);
	short *nts = burm_nts[eruleno];
	Tree kids[10];
	int i;

	for (i = 0; i < indent; i++)
		fprintf(stderr, " ");
	fprintf(stderr, "%s\n", burm_string[eruleno]);
	burm_kids(p, eruleno, kids);
	for (i = 0; nts[i]; i++)
		dumpCover(kids[i], nts[i], indent + 1);
}

static void gen(NODEPTR_TYPE p) {
	if (burm_label(p) == 0)
		fprintf(stderr, "no cover\n");
	else
		dumpCover(p, 1, 0);
}

static Tree tree(int op, Tree l, Tree r) {
	Tree t = malloc(sizeof *t);

	t->op = op;
	t->kids[0] = l; t->kids[1] = r;
	t->val = 0;
	t->x.state = 0;
	return t;
}

main(void) {
	Tree t;

	if (getenv("Trace"))
		trace = atoi(getenv("Trace"));
	printf("i = c + 4;\n");
	t = tree(ASGNI,
		tree(ADDRLP, 0, 0),
		tree(ADDI,
			tree(CVCI, tree(INDIRC, tree(ADDRLP, 0, 0), 0), 0),
			(t = tree(CNSTI, 0, 0), t->val = 4, t)
		)
	);
	gen(t);
	return 0;
}