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Drain increment queues before jumping in matches.

--- a/mi/flatten.c

+++ b/mi/flatten.c

@@ -58,6 +58,7 @@

 static Node *rval(Flattenctx *s, Node *n);

 static Node *lval(Flattenctx *s, Node *n);

 static Node *assign(Flattenctx *s, Node *lhs, Node *rhs);

+static Node *draininc(Flattenctx *c, Node *protect, int free);

 static void

 append(Flattenctx *s, Node *n)

@@ -457,6 +458,30 @@

 	return r;

 }

+/* 

+ * If protect is not null, returns a node with the

+ * unmodified value.

+ */

+static Node*

+draininc(Flattenctx *fc, Node *protect, int free)

+{

+	Node *tmp;

+	size_t i;

+

+	tmp = NULL;

+	if (!fc->nqueue)

+		return protect;

+	if (protect) {

+		tmp = temp(fc, protect);

+		append(fc, assign(fc, tmp, protect));

+	}

+	for (i = 0; i < fc->nqueue; i++)

+		append(fc, fc->incqueue[i]);

+	if (free)

+		lfree(&fc->incqueue, &fc->nqueue);

+	return tmp;

+}

+

 /* returns 1 when the exit jump needs to be emitted */

 static int

 exitscope(Flattenctx *s, Stab *stop, Srcloc loc, Exit x)

@@ -488,7 +513,6 @@

 	Node *t, *u, *v; /* temporary nodes */

 	Node *r; /* expression result */

 	Node **args;

-	size_t i;

 	Type *ty;

 	const Op fusedmap[Numops] = {

@@ -607,18 +631,8 @@

 		r = n;

 		break;;

 	case Oret:

-		/* drain the increment queue before we return */

 		v = rval(s, args[0]);

-		if (!s->nqueue) {

-			t = v;

-		} else {

-			t = temp(s, v);

-			u = assign(s, t, v);

-			append(s, u);

-			for (i = 0; i < s->nqueue; i++)

-				append(s, s->incqueue[i]);

-			lfree(&s->incqueue, &s->nqueue);

-		}

+		t = draininc(s, v, 1);

 		if (!s->tret)

 			s->tret = temp(s, v);

 		flatten(s, asn(lval(s, s->tret), t));

@@ -734,7 +748,6 @@

 	Node *ldec;

 	Node *lcond;

 	Node *lstep;

-	size_t i;

 	lbody = genlbl(n->loc);

 	ldec = genlbl(n->loc);

@@ -760,15 +773,11 @@

 	flatten(s, lcond);             /* test lbl */

 	flattencond(s, n->loopstmt.cond, ldec, lend);    /* repeat? */

 	flatten(s, ldec);        	/* drain decrements */

-	for (i = 0; i < s->nqueue; i++)

-		append(s, s->incqueue[i]);

+	draininc(s, NULL, 0);

 	jmp(s, lbody);              	/* goto test */

 	flatten(s, lend);             	/* exit */

+	draininc(s, NULL, 1);

-	for (i = 0; i < s->nqueue; i++)

-		append(s, s->incqueue[i]);

-	lfree(&s->incqueue, &s->nqueue);

-

 	s->inloop--;

 	s->loop = l;

 	s->curst = b;

@@ -781,7 +790,6 @@

 {

 	Node *l1, *l2, *l3;

 	Node *iftrue, *iffalse;

-	size_t i;

 	l1 = genlbl(n->loc);

 	l2 = genlbl(n->loc);

@@ -795,15 +803,12 @@

 	flattencond(s, n->ifstmt.cond, l1, l2);

 	flatten(s, l1);

-	for (i = 0; i < s->nqueue; i++)

-		append(s, s->incqueue[i]);

+	draininc(s, NULL, 0);

 	/* goto test */

 	flatten(s, iftrue);

 	jmp(s, l3);

 	flatten(s, l2);

-	for (i = 0; i < s->nqueue; i++)

-		append(s, s->incqueue[i]);

-	lfree(&s->incqueue, &s->nqueue);

+	draininc(s, NULL, 1);

 	/* because lots of bunched up end labels are ugly,

 	 * coalesce them by handling 'elif'-like construct

 	 * separately */

@@ -1007,14 +1012,15 @@

 	default:	flattentraititer(s, n);	break;

 	}

 }

+

 static void

 flattenmatch(Flattenctx *fc, Node *n)

 {

-	Node *val;

-	Node **match;

+	Node *val, **match;

 	size_t i, nmatch;

 	val = rval(fc, n->matchstmt.val);

+	val = draininc(fc, val, 1);

 	match = NULL;

 	nmatch = 0;

@@ -1027,19 +1033,15 @@

 flattenexpr(Flattenctx *fc, Node *n)

 {

 	Node *r;

-	size_t i;

 	if (islbl(n)) {

 		append(fc, n);

 		return;

 	}

-

 	r = rval(fc, n);

 	if (r)

 		append(fc, r);

-	for (i = 0; i < fc->nqueue; i++)

-		append(fc, fc->incqueue[i]);

-	lfree(&fc->incqueue, &fc->nqueue);

+	draininc(fc, NULL, 1);

 }

 static Node *