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[cc2] Optimize jumps to jumps statements

In this case of statements we are wasting time jumping
to another jump. We can jump directly to the target jump.

--- a/cc2/optm.c

+++ b/cc2/optm.c

@@ -5,5 +5,15 @@

 Node *

 optm(Node *np)

 {

+	Node *dst;

+

+	switch (np->op) {

+	case OJMP:

+	case OBRANCH:

+		dst = np->u.sym->u.stmt;

+		if (dst->op == OJMP)

+			np->u.sym = dst->u.sym;

+		break;

+	}

 	return np;

 }

--- a/cc2/parser.c

+++ b/cc2/parser.c

@@ -577,6 +577,7 @@

 	np->op = ONOP;

 	sym = np->u.sym;

 	sym->kind = SLABEL;

+	sym->u.stmt = np;

 	np->label = sym;

 	addstmt(np);

 }