Bug fixed in optimizing two adjacent basic blocks.

diff --git a/util/ego/cs/cs.c b/util/ego/cs/cs.c
index 502e143..bc59924 100644 (file)
--- a/util/ego/cs/cs.c
+++ b/util/ego/cs/cs.c
@@ -1,3 +1,4 @@
+
 /* C O M M O N   S U B E X P R E S S I O N   E L I M I N A T I O N */
 
 
@@ -41,17 +42,19 @@ STATIC cs_optimize(p)
        rbp = p->p_start;
 
        while (rbp != (bblock_p) 0) {
-               bdone = rbp->b_idom;
                /* First we build a list of common expressions with the
                 * value numbering algorithm. We take blocks in textual order
                 * as long as the next block can only be reached through the
-                * block we have just done.
+                * block we have just done. Note that if a block is preceded
+                * by itself, the number of predecessors is greater than 1,
+                * but the previous block can still be its immediate dominator.
                 */
-               while (rbp != (bblock_p) 0 && rbp->b_idom == bdone) {
-                       vnm(rbp); bdone = rbp;
+               do {    vnm(rbp); bdone = rbp;
                        OUTTRACE("basic block %d processed", bdone->b_id);
                        rbp = rbp->b_next;
-               }
+               } while (rbp != (bblock_p) 0 && rbp->b_idom == bdone &&
+                       Lnrelems(rbp->b_pred) == 1
+               );
                OUTTRACE("value numbering completed", 0);
                OUTAVAILS(); OUTENTITIES();