dag.c

quakeIII源码这个不用我多说吧

		      	addlocal(tp->u.sym);
		      p = node(tp->op + sizeop(voidptype->size), NULL, NULL, tp->u.sym); } break;
	default:assert(0);
	}
	tp->node = p;
	return p;
}
static void list(Node p) {
	if (p && p->link == NULL) {
		if (forest) {
			p->link = forest->link;
			forest->link = p;
		} else
			p->link = p;
		forest = p;
	}
}
static void labelnode(int lab) {
	assert(lab);
	if (forest && forest->op == LABEL+V)
		equatelab(findlabel(lab), forest->syms[0]);
	else
		list(newnode(LABEL+V, NULL, NULL, findlabel(lab)));
	reset();
}
static void unlist(void) {
	Node p;

	assert(forest);
	assert(forest != forest->link);
	p = forest->link;
	while (p->link != forest)
		p = p->link;
	p->link = forest->link;
	forest = p;
}
Tree cvtconst(Tree p) {
	Symbol q = constant(p->type, p->u.v);
	Tree e;

	if (q->u.c.loc == NULL)
		q->u.c.loc = genident(STATIC, p->type, GLOBAL);
	if (isarray(p->type)) {
		e = simplify(ADDRG, atop(p->type), NULL, NULL);
		e->u.sym = q->u.c.loc;
	} else
		e = idtree(q->u.c.loc);
	return e;
}
void gencode(Symbol caller[], Symbol callee[]) {
	Code cp;
	Coordinate save;

	if (prunetemps == -1)
		prunetemps = !IR->wants_dag;
	save = src;
	if (assignargs) {
		int i;
		Symbol p, q;
		cp = codehead.next->next;
		codelist = codehead.next;
		for (i = 0; (p = callee[i]) != NULL
		         && (q = caller[i]) != NULL; i++)
			if (p->sclass != q->sclass || p->type != q->type)
				walk(asgn(p, idtree(q)), 0, 0);
		codelist->next = cp;
		cp->prev = codelist;
	}
	if (glevel && IR->stabsym) {
		int i;
		Symbol p, q;
		for (i = 0; (p = callee[i]) != NULL
		         && (q = caller[i]) != NULL; i++) {
			(*IR->stabsym)(p);
			if (p->sclass != q->sclass || p->type != q->type)
				(*IR->stabsym)(q);
		}
		swtoseg(CODE);
	}
	cp = codehead.next;
	for ( ; errcnt <= 0 && cp; cp = cp->next)
		switch (cp->kind) {
		case Address:  (*IR->address)(cp->u.addr.sym, cp->u.addr.base,
			       	cp->u.addr.offset); break;
		case Blockbeg: {
			       	Symbol *p = cp->u.block.locals;
			       	(*IR->blockbeg)(&cp->u.block.x);
			       	for ( ; *p; p++)
			       		if ((*p)->ref != 0.0)
			       			(*IR->local)(*p);
			       		else if (glevel) (*IR->local)(*p);
			       }
 break;
		case Blockend: (*IR->blockend)(&cp->u.begin->u.block.x); break;
		case Defpoint: src = cp->u.point.src; break;
		case Gen: case Jump:
		case Label:    if (prunetemps)
			       	cp->u.forest = prune(cp->u.forest);
			       fixup(cp->u.forest);
			       cp->u.forest = (*IR->gen)(cp->u.forest); break;
		case Local:    (*IR->local)(cp->u.var); break;
		case Switch:   break;
		default: assert(0);
		}
	src = save;
}
static void fixup(Node p) {
	for ( ; p; p = p->link)
		switch (generic(p->op)) {
		case JUMP:
			if (specific(p->kids[0]->op) == ADDRG+P)
				p->kids[0]->syms[0] =
					equated(p->kids[0]->syms[0]);
			break;
		case LABEL: assert(p->syms[0] == equated(p->syms[0])); break;
		case EQ: case GE: case GT: case LE: case LT: case NE:
			assert(p->syms[0]);
			p->syms[0] = equated(p->syms[0]);
		}
}
static Symbol equated(Symbol p) {
	{ Symbol q; for (q = p->u.l.equatedto; q; q = q->u.l.equatedto) assert(p != q); }
	while (p->u.l.equatedto)
		p = p->u.l.equatedto;
	return p;
}
void emitcode(void) {
	Code cp;
	Coordinate save;

	save = src;
	cp = codehead.next;
	for ( ; errcnt <= 0 && cp; cp = cp->next)
		switch (cp->kind) {
		case Address: break;
		case Blockbeg: if (glevel && IR->stabblock) {
			       	(*IR->stabblock)('{',  cp->u.block.level - LOCAL, cp->u.block.locals);
			       	swtoseg(CODE);
			       }
 break;
		case Blockend: if (glevel && IR->stabblock) {
			       	Code bp = cp->u.begin;
			       	foreach(bp->u.block.identifiers, bp->u.block.level, typestab, NULL);
			       	foreach(bp->u.block.types,       bp->u.block.level, typestab, NULL);
			       	(*IR->stabblock)('}', bp->u.block.level - LOCAL, bp->u.block.locals);
			       	swtoseg(CODE);
			       }
 break;
		case Defpoint: src = cp->u.point.src;
			       if (glevel > 0 && IR->stabline) {
			       	(*IR->stabline)(&cp->u.point.src); swtoseg(CODE); } break;
		case Gen: case Jump:
		case Label:    if (cp->u.forest)
			       	(*IR->emit)(cp->u.forest); break;
		case Local:    if (glevel && IR->stabsym) {
			       	(*IR->stabsym)(cp->u.var);
			       	swtoseg(CODE);
			       } break;
		case Switch:   {	int i;
			       	defglobal(cp->u.swtch.table, LIT);
			       	(*IR->defaddress)(equated(cp->u.swtch.labels[0]));
			       	for (i = 1; i < cp->u.swtch.size; i++) {
			       		long k = cp->u.swtch.values[i-1];
			       		while (++k < cp->u.swtch.values[i])
			       			assert(k < LONG_MAX),
			       			(*IR->defaddress)(equated(cp->u.swtch.deflab));
			       		(*IR->defaddress)(equated(cp->u.swtch.labels[i]));
			       	}
			       	swtoseg(CODE);
			       } break;
		default: assert(0);
		}
	src = save;
}

static Node undag(Node forest) {
	Node p;

	tail = &forest;
	for (p = forest; p; p = p->link)
		if (generic(p->op) == INDIR) {
			assert(p->count >= 1);
			visit(p, 1);
			if (p->syms[2]) {
				assert(p->syms[2]->u.t.cse);
				p->syms[2]->u.t.cse = NULL;
				addlocal(p->syms[2]);
			}
		} else if (iscall(p->op) && p->count >= 1)
			visit(p, 1);
		else {
			assert(p->count == 0),
			visit(p, 1);
			*tail = p;
			tail = &p->link;
		}
	*tail = NULL;
	return forest;
}
static Node replace(Node p) {
	if (p && (  generic(p->op) == INDIR
		 && generic(p->kids[0]->op) == ADDRL
		 && p->kids[0]->syms[0]->temporary
		 && p->kids[0]->syms[0]->u.t.replace)) {
		p = p->kids[0]->syms[0]->u.t.cse;
		if (generic(p->op) == INDIR && isaddrop(p->kids[0]->op))
			p = newnode(p->op, newnode(p->kids[0]->op, NULL, NULL,
				p->kids[0]->syms[0]), NULL, NULL);
		else if (generic(p->op) == ADDRG)
			p = newnode(p->op, NULL, NULL, p->syms[0]);
		else
			assert(0);
		p->count = 1;
	} else if (p) {
		p->kids[0] = replace(p->kids[0]);
		p->kids[1] = replace(p->kids[1]);
	}
	return p;
}
static Node prune(Node forest) {
	Node p, *tail = &forest;
	int count = 0;

	for (p = forest; p; p = p->link) {
		if (count > 0) {
			p->kids[0] = replace(p->kids[0]);
			p->kids[1] = replace(p->kids[1]);
		}
		if ((  generic(p->op) == ASGN
		    && generic(p->kids[0]->op) == ADDRL
		    && p->kids[0]->syms[0]->temporary
		    && p->kids[0]->syms[0]->u.t.cse == p->kids[1])) {
			Symbol tmp = p->kids[0]->syms[0];
			if (!tmp->defined)
				(*IR->local)(tmp);
			tmp->defined = 1;
			if ((  generic(p->kids[1]->op) == INDIR
			    && isaddrop(p->kids[1]->kids[0]->op)
			    && p->kids[1]->kids[0]->syms[0]->sclass == REGISTER)
			|| ((  generic(p->kids[1]->op) == INDIR
			    && isaddrop(p->kids[1]->kids[0]->op)) && tmp->sclass == AUTO)
			|| (generic(p->kids[1]->op) == ADDRG && tmp->sclass == AUTO)) {
				tmp->u.t.replace = 1;
				count++;
				continue;	/* and omit the assignment */
			}
		}
		/* keep the assignment and other roots */
		*tail = p;
		tail = &(*tail)->link;
	}
	assert(*tail == NULL);
	return forest;
}
static Node visit(Node p, int listed) {
	if (p)
		if (p->syms[2])
			p = tmpnode(p);
		else if (p->count <= 1 && !iscall(p->op)
		||       p->count == 0 &&  iscall(p->op)) {
			p->kids[0] = visit(p->kids[0], 0);
			p->kids[1] = visit(p->kids[1], 0);
		}

		else if (specific(p->op) == ADDRL+P || specific(p->op) == ADDRF+P) {
			assert(!listed);
			p = newnode(p->op, NULL, NULL, p->syms[0]);
			p->count = 1;
		}
		else if (p->op == INDIR+B) {
			p = newnode(p->op, p->kids[0], NULL, NULL);
			p->count = 1;
			p->kids[0] = visit(p->kids[0], 0);
			p->kids[1] = visit(p->kids[1], 0);
		}
		else {
			p->kids[0] = visit(p->kids[0], 0);
			p->kids[1] = visit(p->kids[1], 0);
			p->syms[2] = temporary(REGISTER, btot(p->op, opsize(p->op)));
			assert(!p->syms[2]->defined);
			p->syms[2]->ref = 1;
			p->syms[2]->u.t.cse = p;

			*tail = asgnnode(p->syms[2], p);
			tail = &(*tail)->link;
			if (!listed)
				p = tmpnode(p);
		};
	return p;
}
static Node tmpnode(Node p) {
	Symbol tmp = p->syms[2];

	assert(tmp);
	if (--p->count == 0)
		p->syms[2] = NULL;
	p = newnode(INDIR + ttob(tmp->type),
		newnode(ADDRL + ttob(voidptype), NULL, NULL, tmp), NULL, NULL);
	p->count = 1;
	return p;
}
static Node asgnnode(Symbol tmp, Node p) {
	p = newnode(ASGN + ttob(tmp->type),
		newnode(ADDRL + ttob(voidptype), NULL, NULL, tmp), p, NULL);
	p->syms[0] = intconst(tmp->type->size);
	p->syms[1] = intconst(tmp->type->align);
	return p;
}
/* printdag - print dag p on fd, or the node list if p == 0 */
void printdag(Node p, int fd) {
	FILE *f = fd == 1 ? stdout : stderr;

	printed(0);
	if (p == 0) {
		if ((p = forest) != NULL)
			do {
				p = p->link;
				printdag1(p, fd, 0);
			} while (p != forest);
	} else if (*printed(nodeid((Tree)p)))
		fprint(f, "node'%d printed above\n", nodeid((Tree)p));
	else
		printdag1(p, fd, 0);
}

/* printdag1 - recursively print dag p */
static void printdag1(Node p, int fd, int lev) {
	int id, i;

	if (p == 0 || *printed(id = nodeid((Tree)p)))
		return;
	*printed(id) = 1;
	for (i = 0; i < NELEMS(p->kids); i++)
		printdag1(p->kids[i], fd, lev + 1);
	printnode(p, fd, lev);
}

/* printnode - print fields of dag p */
static void printnode(Node p, int fd, int lev) {
	if (p) {
		FILE *f = fd == 1 ? stdout : stderr;
		int i, id = nodeid((Tree)p);
		fprint(f, "%c%d%s", lev == 0 ? '\'' : '#', id,
			&"   "[id < 10 ? 0 : id < 100 ? 1 : 2]);
		fprint(f, "%s count=%d", opname(p->op), p->count);
		for (i = 0; i < NELEMS(p->kids) && p->kids[i]; i++)
			fprint(f, " #%d", nodeid((Tree)p->kids[i]));
		if (generic(p->op) == CALL && p->syms[0] && p->syms[0]->type)
			fprint(f, " {%t}", p->syms[0]->type);
		else
			for (i = 0; i < NELEMS(p->syms) && p->syms[i]; i++)
				if (p->syms[i]->name)
					fprint(f, " %s", p->syms[i]->name);
				else
					fprint(f, " %p", p->syms[i]);
		fprint(f, "\n");
	}
}

/* typestab - emit stab entries for p */
static void typestab(Symbol p, void *cl) {
	if (!isfunc(p->type) && (p->sclass == EXTERN || p->sclass == STATIC) && IR->stabsym)
		(*IR->stabsym)(p);
	else if ((p->sclass == TYPEDEF || p->sclass == 0) && IR->stabtype)
		(*IR->stabtype)(p);
}