fixed another bug with header blocks, and modified to use existing header

block when possible

util/ego/sr/sr.c

@@ -155,6 +155,27 @@ STATIC opt_proc(p)
 
 
 
+STATIC bblock_p header(lp)
+	loop_p lp;
+{
+	/* Try to determine the 'header' block of loop lp.
+	 * If 'e' is the entry block of loop L, then block 'b' is
+	 * called the header block of L, iff:
+	 *	SUCC(b) = {e} & b dominates e.
+	 * If lp has no header block, 0 is returned.
+	 */
+
+	bblock_p x = lp->lp_entry->b_idom;
+
+	if (x != (bblock_p) 0 && Lnrelems(x->b_succ) == 1 &&
+	    (bblock_p) Lelem(Lfirst(x->b_succ)) == lp->lp_entry) {
+		return x;
+	}
+	return (bblock_p) 0;
+}
+
+
+
 STATIC sr_extproc(p)
 	proc_p p;
 {
@@ -167,11 +188,14 @@ STATIC sr_extproc(p)
 	   pi = Lnext(pi,p->p_loops)) {
 		lp = (loop_p) Lelem(pi);
 		lp->lp_extend = newsrlpx();
+		lp->LP_HEADER = header(lp);
+		if (lp->LP_HEADER) {
+			lp->LP_INSTR = last_instr(lp->LP_HEADER);
+		}
 	}
 }
 
 
-
 STATIC sr_cleanproc(p)
 	proc_p p;
 {

util/ego/sr/sr_reduce.c

@@ -146,6 +146,25 @@ STATIC replcode(code,text)
 	/* Note that the old code is still accessible via code->co_lfirst */
 }
 
+STATIC line_p add_code(pl, l)
+	line_p pl, l;
+{
+	if (! pl) {
+		PREV(l) = 0;
+	}
+	else {
+		line_p n = pl->l_next;
+
+		DLINK(pl, l);
+		if (n) {
+			while (l->l_next) l = l->l_next;
+			DLINK(l, n);
+		}
+		l = pl;
+	}
+	return l;
+}
+
 
 
 STATIC init_code(code,tmp)
@@ -193,21 +212,20 @@ STATIC init_code(code,tmp)
 	PREV(l->l_next) = l;
 	/* Now insert the code at the end of the header block */
 	p = &code->co_loop->LP_INSTR;
-	if (*p == (line_p) 0) {
+	if (*p == (line_p) 0 || (PREV((*p)) == 0 && INSTR((*p)) == op_bra)) {
 		/* LP_INSTR points to last instruction of header block,
 		 * so if it is 0, the header block is empty yet.
 		 */
 		code->co_loop->LP_HEADER->b_start =
-		    code->co_lfirst;
+		  add_code(code->co_loop->LP_HEADER->b_start, code->co_lfirst);
-	} else {
+	} else if (INSTR((*p)) == op_bra) {
-		(*p)->l_next = code->co_lfirst;
+		add_code(PREV((*p)), code->co_lfirst);
-		PREV(code->co_lfirst) = *p;
 	}
-	*p = l->l_next; /* new last instruction */
+	else	add_code(*p, code->co_lfirst);
+	while (l->l_next) l = l->l_next;
+	*p = l; /* new last instruction */
 }
 
-
-
 STATIC incr_code(code,tmp)
 	code_p  code;
 	offset  tmp;

util/ego/sr/sr_xform.c

@@ -116,17 +116,25 @@ STATIC adjust_jump(newtarg,oldtarg,c)
 	 * start of the new target.
 	 */
 
-	line_p l;
+	line_p l = last_instr(c);
+
+	assert(l != (line_p) 0);
 
 	if (INSTR(oldtarg->b_start) == op_lab) {
 		/* If old target has no label, it cannot be jumped to */
-		l = last_instr(c);
-		assert(l != (line_p) 0);
 		if (TYPE(l) == OPINSTRLAB &&
 		    INSTRLAB(l) == INSTRLAB(oldtarg->b_start)) {
 			INSTRLAB(l) = label(newtarg);
 		}
 	}
+
+	if (c->b_next == oldtarg && INSTR(l) != op_bra) {
+		line_p new = newline(OPINSTRLAB);
+
+		INSTRLAB(new) = label(newtarg);
+		new->l_instr = op_bra;
+		DLINK(l, new);
+	}
 }