lburg.c

lcc,一个可变目标c语言编译器的源码

        p->reached = 1;
	for (r = p->rules; r; r = r->decode)
		reach(r->pattern);
}

/* emitcase - emit one case in function state */
static void emitcase(Term p, int ntnumber) {
	Rule r;

	print("%1case %d: /* %S */\n", p->esn, p);
	switch (p->arity) {
	case 0: case -1:
		break;
	case 1:
		print("%2%Plabel(LEFT_CHILD(a));\n");
		break;
	case 2:
		print("%2%Plabel(LEFT_CHILD(a));\n");
		print("%2%Plabel(RIGHT_CHILD(a));\n");
		break;
	default: assert(0);
	}
	for (r = p->rules; r; r = r->next) {
		char *indent = "\t\t\0";
		switch (p->arity) {
		case 0: case -1:
			print("%2/* %R */\n", r);
			if (r->cost == -1) {
				print("%2c = %s;\n", r->code);
				emitrecord("\t\t", r, "c", 0);
			} else
				emitrecord("\t\t", r, r->code, 0);
			break;
		case 1:
			if (r->pattern->nterms > 1) {
				print("%2if (%1/* %R */\n", r);
				emittest(r->pattern->left, "LEFT_CHILD(a)", " ");
				print("%2) {\n");
				indent = "\t\t\t";
			} else
				print("%2/* %R */\n", r);
			if (r->pattern->nterms == 2 && r->pattern->left
			&&  r->pattern->right == NULL)
				emitrecalc(indent, r->pattern->op, r->pattern->left->op);
			print("%sc = ", indent);
			emitcost(r->pattern->left, "LEFT_CHILD(a)");
			print("%s;\n", r->code);
			emitrecord(indent, r, "c", 0);
			if (indent[2])
				print("%2}\n");
			break;
		case 2:
			if (r->pattern->nterms > 1) {
				print("%2if (%1/* %R */\n", r);
				emittest(r->pattern->left,  "LEFT_CHILD(a)",
					r->pattern->right->nterms ? " && " : " ");
				emittest(r->pattern->right, "RIGHT_CHILD(a)", " ");
				print("%2) {\n");
				indent = "\t\t\t";
			} else
				print("%2/* %R */\n", r);
			print("%sc = ", indent);
			emitcost(r->pattern->left,  "LEFT_CHILD(a)");
			emitcost(r->pattern->right, "RIGHT_CHILD(a)");
			print("%s;\n", r->code);
			emitrecord(indent, r, "c", 0);
			if (indent[2])
				print("%2}\n");
			break;
		default: assert(0);
		}
	}
	print("%2break;\n");
}

/* emitclosure - emit the closure functions */
static void emitclosure(Nonterm nts) {
	Nonterm p;

	for (p = nts; p; p = p->link)
		if (p->chain)
			print("static void %Pclosure_%S(NODEPTR_TYPE, int);\n", p);
	print("\n");
	for (p = nts; p; p = p->link)
		if (p->chain) {
			Rule r;
			print("static void %Pclosure_%S(NODEPTR_TYPE a, int c) {\n"
"%1struct %Pstate *p = STATE_LABEL(a);\n", p);
			for (r = p->chain; r; r = r->chain)
				emitrecord("\t", r, "c", r->cost);
			print("}\n\n");
		}
}

/* emitcost - emit cost computation for tree t */
static void emitcost(Tree t, char *v) {
	Nonterm p = t->op;

	if (p->kind == TERM) {
		if (t->left)
			emitcost(t->left,  stringf("LEFT_CHILD(%s)",  v));
		if (t->right)
			emitcost(t->right, stringf("RIGHT_CHILD(%s)", v));
	} else
		print("((struct %Pstate *)(%s->x.state))->cost[%P%S_NT] + ", v, p);
}

/* emitdefs - emit nonterminal defines and data structures */
static void emitdefs(Nonterm nts, int ntnumber) {
	Nonterm p;

	for (p = nts; p; p = p->link)
		print("#define %P%S_NT %d\n", p, p->number);
	print("\n");
	print("static char *%Pntname[] = {\n%10,\n");
	for (p = nts; p; p = p->link)
		print("%1\"%S\",\n", p);
	print("%10\n};\n\n");
}

/* emitheader - emit initial definitions */
static void emitheader(void) {
	time_t timer = time(NULL);

	print("/*\ngenerated at %sby %s\n*/\n", ctime(&timer), rcsid);
	print("static void %Pkids(NODEPTR_TYPE, int, NODEPTR_TYPE[]);\n");
	print("static void %Plabel(NODEPTR_TYPE);\n");
	print("static int %Prule(void*, int);\n\n");
}

/* computekids - compute paths to kids in tree t */
static char *computekids(Tree t, char *v, char *bp, int *ip) {
	Term p = t->op;

	if (p->kind == NONTERM) {
		sprintf(bp, "\t\tkids[%d] = %s;\n", (*ip)++, v);
		bp += strlen(bp);
	} else if (p->arity > 0) {
		bp = computekids(t->left, stringf("LEFT_CHILD(%s)", v), bp, ip);
		if (p->arity == 2)
			bp = computekids(t->right, stringf("RIGHT_CHILD(%s)", v), bp, ip);
	}
	return bp;
}

/* emitkids - emit _kids */
static void emitkids(Rule rules, int nrules) {
	int i;
	Rule r, *rc = alloc((nrules + 1 + 1)*sizeof *rc);
	char **str  = alloc((nrules + 1 + 1)*sizeof *str);

	for (i = 0, r = rules; r; r = r->link) {
		int j = 0;
		char buf[1024], *bp = buf;
		*computekids(r->pattern, "p", bp, &j) = 0;
		for (j = 0; str[j] && strcmp(str[j], buf); j++)
			;
		if (str[j] == NULL)
			str[j] = strcpy(alloc(strlen(buf) + 1), buf);
		r->kids = rc[j];
		rc[j] = r;
	}
	print("static void %Pkids(NODEPTR_TYPE p, int eruleno, NODEPTR_TYPE kids[]) {\n"
"%1if (!p)\n%2fatal(\"%Pkids\", \"Null tree\\n\", 0);\n"
"%1if (!kids)\n%2fatal(\"%Pkids\", \"Null kids\\n\", 0);\n"
"%1switch (eruleno) {\n");
	for (i = 0; (r = rc[i]) != NULL; i++) {
		for ( ; r; r = r->kids)
			print("%1case %d: /* %R */\n", r->ern, r);
		print("%s%2break;\n", str[i]);
	}
	print("%1default:\n%2fatal(\"%Pkids\", \"Bad rule number %%d\\n\", eruleno);\n%1}\n}\n\n");
}

/* emitlabel - emit label function */
static void emitlabel(Term terms, Nonterm start, int ntnumber) {
	int i;
	Term p;

	print("static void %Plabel(NODEPTR_TYPE a) {\n%1int c;\n"
"%1struct %Pstate *p;\n\n"
"%1if (!a)\n%2fatal(\"%Plabel\", \"Null tree\\n\", 0);\n");
	print("%1STATE_LABEL(a) = p = allocate(sizeof *p, FUNC);\n"
"%1p->rule._stmt = 0;\n");
	for (i = 1; i <= ntnumber; i++)
		print("%1p->cost[%d] =\n", i);
	print("%20x7fff;\n%1switch (OP_LABEL(a)) {\n");
	for (p = terms; p; p = p->link)
		emitcase(p, ntnumber);
	print("%1default:\n"
"%2fatal(\"%Plabel\", \"Bad terminal %%d\\n\", OP_LABEL(a));\n%1}\n}\n\n");
}

/* computents - fill in bp with _nts vector for tree t */
static char *computents(Tree t, char *bp) {
	if (t) {
		Nonterm p = t->op;
		if (p->kind == NONTERM) {
			sprintf(bp, "%s_%s_NT, ", prefix, p->name);
			bp += strlen(bp);
		} else
			bp = computents(t->right, computents(t->left,  bp));
	}
	return bp;
}

/* emitnts - emit _nts ragged array */
static void emitnts(Rule rules, int nrules) {
	Rule r;
	int i, j, *nts = alloc((nrules + 1)*sizeof *nts);
	char **str = alloc((nrules + 1)*sizeof *str);

	for (i = 0, r = rules; r; r = r->link) {
		char buf[1024];
		*computents(r->pattern, buf) = 0;
		for (j = 0; str[j] && strcmp(str[j], buf); j++)
			;
		if (str[j] == NULL) {
			print("static short %Pnts_%d[] = { %s0 };\n", j, buf);
			str[j] = strcpy(alloc(strlen(buf) + 1), buf);
		}
		nts[i++] = j;
	}
	print("\nstatic short *%Pnts[] = {\n");
	for (i = j = 0, r = rules; r; r = r->link) {
		for ( ; j < r->ern; j++)
			print("%10,%1/* %d */\n", j);
		print("%1%Pnts_%d,%1/* %d */\n", nts[i++], j++);
	}
	print("};\n\n");
}

/* emitrecalc - emit code that tests for recalculation of INDIR?(VREGP) */
static void emitrecalc(char *pre, Term root, Term kid) {
	if (root->kind == TERM && strncmp(root->name, "INDIR", 5) == 0
	&&   kid->kind == TERM &&  strcmp(kid->name,  "VREGP"   ) == 0) {
		Nonterm p;
		print("%sif (mayrecalc(a)) {\n", pre);
		print("%s%1struct %Pstate *q = a->syms[RX]->u.t.cse->x.state;\n", pre);
		for (p = nts; p; p = p->link) {
			print("%s%1if (q->cost[%P%S_NT] == 0) {\n", pre, p);
			print("%s%2p->cost[%P%S_NT] = 0;\n", pre, p);
			print("%s%2p->rule.%P%S = q->rule.%P%S;\n", pre, p, p);
			print("%s%1}\n", pre);
		}
		print("%s}\n", pre);
	}
}

/* emitrecord - emit code that tests for a winning match of rule r */
static void emitrecord(char *pre, Rule r, char *c, int cost) {
	if (Tflag)
		print("%s%Ptrace(a, %d, %s + %d, p->cost[%P%S_NT]);\n",
			pre, r->ern, c, cost, r->lhs);
	print("%sif (", pre);
	print("%s + %d < p->cost[%P%S_NT]) {\n"
"%s%1p->cost[%P%S_NT] = %s + %d;\n%s%1p->rule.%P%S = %d;\n",
		c, cost, r->lhs, pre, r->lhs, c, cost, pre, r->lhs,
		r->packed);
	if (r->lhs->chain)
		print("%s%1%Pclosure_%S(a, %s + %d);\n", pre, r->lhs, c, cost);
	print("%s}\n", pre);
}

/* emitrule - emit decoding vectors and _rule */
static void emitrule(Nonterm nts) {
	Nonterm p;

	for (p = nts; p; p = p->link) {
		Rule r;
		print("static short %Pdecode_%S[] = {\n%10,\n", p);
		for (r = p->rules; r; r = r->decode)
			print("%1%d,\n", r->ern);
		print("};\n\n");
	}
	print("static int %Prule(void *state, int goalnt) {\n"
"%1if (goalnt < 1 || goalnt > %d)\n%2fatal(\"%Prule\", \"Bad goal nonterminal %%d\\n\", goalnt);\n"
"%1if (!state)\n%2return 0;\n%1switch (goalnt) {\n", ntnumber);
	for (p = nts; p; p = p->link)
		print("%1case %P%S_NT:"
"%1return %Pdecode_%S[((struct %Pstate *)state)->rule.%P%S];\n", p, p, p);
	print("%1default:\n%2fatal(\"%Prule\", \"Bad goal nonterminal %%d\\n\", goalnt);\n%2return 0;\n%1}\n}\n\n");
}

/* emitstring - emit arrays of templates, instruction flags, and rules */
static void emitstring(Rule rules) {
	Rule r;

	print("static char *%Ptemplates[] = {\n");
	print("/* 0 */%10,\n");
	for (r = rules; r; r = r->link)
		print("/* %d */%1\"%s\",%1/* %R */\n", r->ern, r->template, r);
	print("};\n");
	print("\nstatic char %Pisinstruction[] = {\n");
	print("/* 0 */%10,\n");
	for (r = rules; r; r = r->link) {
		int len = strlen(r->template);
		print("/* %d */%1%d,%1/* %s */\n", r->ern,
			len >= 2 && r->template[len-2] == '\\' && r->template[len-1] == 'n',
			r->template);
	}
	print("};\n");
	print("\nstatic char *%Pstring[] = {\n");
	print("/* 0 */%10,\n");
	for (r = rules; r; r = r->link)
		print("/* %d */%1\"%R\",\n", r->ern, r);
	print("};\n\n");
}

/* emitstruct - emit the definition of the state structure */
static void emitstruct(Nonterm nts, int ntnumber) {
	print("struct %Pstate {\n%1short cost[%d];\n%1struct {\n", ntnumber + 1);
	for ( ; nts; nts = nts->link) {
		int n = 1, m = nts->lhscount;
		while ((m >>= 1) != 0)
			n++;		
		print("%2unsigned int %P%S:%d;\n", nts, n);
	}
	print("%1} rule;\n};\n\n");
}

/* emittest - emit clause for testing a match */
static void emittest(Tree t, char *v, char *suffix) {
	Term p = t->op;

	if (p->kind == TERM) {
		print("%3%s->op == %d%s/* %S */\n", v, p->esn,
			t->nterms > 1 ? " && " : suffix, p);
		if (t->left)
			emittest(t->left, stringf("LEFT_CHILD(%s)",  v),
				t->right && t->right->nterms ? " && " : suffix);
		if (t->right)
			emittest(t->right, stringf("RIGHT_CHILD(%s)", v), suffix);
	}
}