stmt.c

lcc,一个可变目标c语言编译器的源码

#include "c.h"

static char rcsid[] = "$Id: stmt.c,v 1.1 2002/08/28 23:12:46 drh Exp $";

#define SWSIZE 512

#define den(i,j) ((j-buckets[i]+1.0)/(v[j]-v[buckets[i]]+1))

struct code codehead = { Start };
Code codelist = &codehead;
float density = 0.5;
Table stmtlabs;

static int foldcond(Tree e1, Tree e2);
static void caselabel(Swtch, long, int);
static void cmp(int, Symbol, long, int);
static Tree conditional(int);
static void dostmt(int, Swtch, int);
static int equal(Symbol, Symbol);
static void forstmt(int, Swtch, int);
static void ifstmt(int, int, Swtch, int);
static Symbol localaddr(Tree);
static void stmtlabel(void);
static void swstmt(int, int, int);
static void whilestmt(int, Swtch, int);
Code code(int kind) {
	Code cp;

	if (!reachable(kind))
		warning("unreachable code\n");

	NEW(cp, FUNC);
	cp->kind = kind;
	cp->prev = codelist;
	cp->next = NULL;
	codelist->next = cp;
	codelist = cp;
	return cp;
}
int reachable(int kind) {
	Code cp;

	if (kind > Start) {
		Code cp;
		for (cp = codelist; cp->kind < Label; )
			cp = cp->prev;
		if (cp->kind == Jump || cp->kind == Switch)
			return 0;
	}
	return 1;
}
void addlocal(Symbol p) {
	if (!p->defined) {
		code(Local)->u.var = p;
		p->defined = 1;
		p->scope = level;
	}
}
void definept(Coordinate *p) {
	Code cp = code(Defpoint);

	cp->u.point.src = p ? *p : src;
	cp->u.point.point = npoints;
	if (ncalled > 0) {
		int n = findcount(cp->u.point.src.file,
			cp->u.point.src.x, cp->u.point.src.y);
		if (n > 0)
			refinc = (float)n/ncalled;
	}
	if (glevel > 2)	locus(identifiers, &cp->u.point.src);
	if (events.points && reachable(Gen))
		{
			Tree e = NULL;
			apply(events.points, &cp->u.point.src, &e);
			if (e)
				listnodes(e, 0, 0);
		}
}
void statement(int loop, Swtch swp, int lev) {
	float ref = refinc;

	if (Aflag >= 2 && lev == 15)
		warning("more than 15 levels of nested statements\n");
	switch (t) {
	case IF:       ifstmt(genlabel(2), loop, swp, lev + 1);
 break;
	case WHILE:    whilestmt(genlabel(3), swp, lev + 1); break;
	case DO:       dostmt(genlabel(3), swp, lev + 1); expect(';');
					break;

	case FOR:      forstmt(genlabel(4), swp, lev + 1);
 break;
	case BREAK:    walk(NULL, 0, 0);
		       definept(NULL);
		       if (swp && swp->lab > loop)
		       	branch(swp->lab + 1);
		       else if (loop)
		       	branch(loop + 2);
		       else
		       	error("illegal break statement\n");
		       t = gettok(); expect(';');
					   break;

	case CONTINUE: walk(NULL, 0, 0);
		       definept(NULL);
		       if (loop)
		       	branch(loop + 1);
		       else
		       	error("illegal continue statement\n");
		       t = gettok(); expect(';');
					      break;

	case SWITCH:   swstmt(loop, genlabel(2), lev + 1);
 break;
	case CASE:     {
		       	int lab = genlabel(1);
		       	if (swp == NULL)
		       		error("illegal case label\n");
		       	definelab(lab);
		       	while (t == CASE) {
		       		static char stop[] = { IF, ID, 0 };
		       		Tree p;
		       		t = gettok();
		       		p = constexpr(0);
		       		if (generic(p->op) == CNST && isint(p->type)) {
		       			if (swp) {
		       				needconst++;
		       				p = cast(p, swp->sym->type);
		       				if (p->type->op == UNSIGNED)
		       					p->u.v.i = extend(p->u.v.u, p->type);
		       				needconst--;
		       				caselabel(swp, p->u.v.i, lab);
		       			}
		       		} else
		       			error("case label must be a constant integer expression\n");

		       		test(':', stop);
		       	}
		       	statement(loop, swp, lev);
		       } break;
	case DEFAULT:  if (swp == NULL)
		       	error("illegal default label\n");
		       else if (swp->deflab)
		       	error("extra default label\n");
		       else {
		       	swp->deflab = findlabel(swp->lab);
		       	definelab(swp->deflab->u.l.label);
		       }
		       t = gettok();
		       expect(':');
		       statement(loop, swp, lev); break;
	case RETURN:   {
		       	Type rty = freturn(cfunc->type);
		       	t = gettok();
		       	definept(NULL);
		       	if (t != ';')
		       		if (rty == voidtype) {
		       			error("extraneous return value\n");
		       			expr(0);
		       			retcode(NULL);
		       		} else
		       			retcode(expr(0));
		       	else {
		       		if (rty != voidtype) {
		       			warning("missing return value\n");
		       			retcode(cnsttree(inttype, 0L));
		       		} else
		       			retcode(NULL);
		       	}
		       	branch(cfunc->u.f.label);
		       } expect(';');
					    break;

	case '{':      compound(loop, swp, lev + 1); break;
	case ';':      definept(NULL); t = gettok(); break;
	case GOTO:     walk(NULL, 0, 0);
		       definept(NULL);
		       t = gettok();
		       if (t == ID) {
		       	Symbol p = lookup(token, stmtlabs);
		       	if (p == NULL) {
				p = install(token, &stmtlabs, 0, FUNC);
				p->scope = LABELS;
				p->u.l.label = genlabel(1);
				p->src = src;
			}
		       	use(p, src);
		       	branch(p->u.l.label);
		       	t = gettok();
		       } else
		       	error("missing label in goto\n"); expect(';');
					  break;

	case ID:       if (getchr() == ':') {
		       	stmtlabel();
		       	statement(loop, swp, lev);
		       	break;
		       }
	default:       definept(NULL);
		       if (kind[t] != ID) {
		       	error("unrecognized statement\n");
		       	t = gettok();
		       } else {
		       	Tree e = expr0(0);
		       	listnodes(e, 0, 0);
		       	if (nodecount == 0 || nodecount > 200)
		       		walk(NULL, 0, 0);
		       	else if (glevel) walk(NULL, 0, 0);
		       	deallocate(STMT);
		       } expect(';');
						break;

	}
	if (kind[t] != IF && kind[t] != ID
	&& t != '}' && t != EOI) {
		static char stop[] = { IF, ID, '}', 0 };
		error("illegal statement termination\n");
		skipto(0, stop);
	}
	refinc = ref;
}

static void ifstmt(int lab, int loop, Swtch swp, int lev) {
	t = gettok();
	expect('(');
	definept(NULL);
	walk(conditional(')'), 0, lab);
	refinc /= 2.0;
	statement(loop, swp, lev);
	if (t == ELSE) {
		branch(lab + 1);
		t = gettok();
		definelab(lab);
		statement(loop, swp, lev);
		if (findlabel(lab + 1)->ref)
			definelab(lab + 1);
	} else
		definelab(lab);
}
static Tree conditional(int tok) {
	Tree p = expr(tok);

	if (Aflag > 1 && isfunc(p->type))
		warning("%s used in a conditional expression\n",
			funcname(p));
	return cond(p);
}
static void stmtlabel(void) {
	Symbol p = lookup(token, stmtlabs);

	if (p == NULL) {
		p = install(token, &stmtlabs, 0, FUNC);
		p->scope = LABELS;
		p->u.l.label = genlabel(1);
		p->src = src;
	}
	if (p->defined)
		error("redefinition of label `%s' previously defined at %w\n", p->name, &p->src);

	p->defined = 1;
	definelab(p->u.l.label);
	t = gettok();
	expect(':');
}
static void forstmt(int lab, Swtch swp, int lev) {
	int once = 0;
	Tree e1 = NULL, e2 = NULL, e3 = NULL;
	Coordinate pt2, pt3;
	
	t = gettok();
	expect('(');
	definept(NULL);
	if (kind[t] == ID)
		e1 = texpr(expr0, ';', FUNC);
	else
		expect(';');
	walk(e1, 0, 0);
	pt2 = src;
	refinc *= 10.0;
	if (kind[t] == ID)
		e2 = texpr(conditional, ';', FUNC);
	else
		expect(';');
	pt3 = src;
	if (kind[t] == ID)
		e3 = texpr(expr0, ')', FUNC);
	else {
		static char stop[] = { IF, ID, '}', 0 };
		test(')', stop);
	}
	if (e2) {
		once = foldcond(e1, e2);
		if (!once)
			branch(lab + 3);
	}
	definelab(lab);
	statement(lab, swp, lev);
	definelab(lab + 1);
	definept(&pt3);
	if (e3)
		walk(e3, 0, 0);
	if (e2) {
		if (!once)
			definelab(lab + 3);
		definept(&pt2);
		walk(e2, lab, 0);
	} else {
		definept(&pt2);
		branch(lab);
	}
	if (findlabel(lab + 2)->ref)
		definelab(lab + 2);
}
static void swstmt(int loop, int lab, int lev) {
	Tree e;
	struct swtch sw;
	Code head, tail;

	t = gettok();
	expect('(');
	definept(NULL);
	e = expr(')');
	if (!isint(e->type)) {
		error("illegal type `%t' in switch expression\n",
			e->type);
		e = retype(e, inttype);
	}
	e = cast(e, promote(e->type));
	if (generic(e->op) == INDIR && isaddrop(e->kids[0]->op)
	&& e->kids[0]->u.sym->type == e->type
	&& !isvolatile(e->kids[0]->u.sym->type)) {
		sw.sym = e->kids[0]->u.sym;
		walk(NULL, 0, 0);
	} else {
		sw.sym = genident(REGISTER, e->type, level);
		addlocal(sw.sym);
		walk(asgn(sw.sym, e), 0, 0);
	}
	head = code(Switch);
	sw.lab = lab;
	sw.deflab = NULL;
	sw.ncases = 0;
	sw.size = SWSIZE;
	sw.values = newarray(SWSIZE, sizeof *sw.values, FUNC);
	sw.labels = newarray(SWSIZE, sizeof *sw.labels, FUNC);
	refinc /= 10.0;
	statement(loop, &sw, lev);
	if (sw.deflab == NULL) {
		sw.deflab = findlabel(lab);
		definelab(lab);
		if (sw.ncases == 0)
			warning("switch statement with no cases\n");
	}
	if (findlabel(lab + 1)->ref)
		definelab(lab + 1);