Index: tree-ssa-pre.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Attic/tree-ssa-pre.c,v
retrieving revision 1.1.4.94
diff -u -3 -p -r1.1.4.94 tree-ssa-pre.c
--- tree-ssa-pre.c	24 Oct 2003 07:41:31 -0000	1.1.4.94
+++ tree-ssa-pre.c	29 Oct 2003 15:03:21 -0000
@@ -323,7 +323,8 @@ struct expr_info
 
 /* Cache of expressions generated for given phi operand, to avoid
    recomputation and wasting memory.  */
-tree *phi_pred_cache;
+static tree *phi_pred_cache;
+static int n_phi_preds;
 
 /* Trying to lookup ephi pred operand indexes takes forever on graphs
    that have high connectivity because it's an O(n) linked list
@@ -1193,7 +1224,6 @@
 /* Make a copy of Z as it would look in BB j, using the PHIs in BB.  */
 
 static tree
 subst_phis (struct expr_info *ei, tree Z, basic_block j, basic_block bb)
 {
   tree stmt_copy;
-  if (phi_pred_cache[j->index] != NULL_TREE)
@@ -1200,6 +1232,12 @@
+
+  /* Return the cached version, if we have one. */
+  if (j->index < n_phi_preds 
+      && phi_pred_cache[j->index] != NULL_TREE)
     return phi_pred_cache[j->index];
+
+  /* Otherwise, generate a new expression.  */
   pre_stats.exprs_generated++;
   stmt_copy = unshare_expr (Z);
   create_stmt_ann (stmt_copy);
   modify_stmt (stmt_copy);
   get_stmt_operands (stmt_copy);
@@ -1210,1 +1248,0 @@
-  phi_pred_cache[j->index] = stmt_copy;
@@ -1211,3 +1273,6 @@
+
+  if (j->index < n_phi_preds)
+    phi_pred_cache[j->index] = stmt_copy;
   return stmt_copy;
 }
 
@@ -3045,6 +3129,7 @@ pre_expression (struct expr_info *slot, 
   bitmap_clear (created_phi_preds);
   ephi_pindex_htab = htab_create (500, ephi_pindex_hash, ephi_pindex_eq, free);
   phi_pred_cache = xcalloc (last_basic_block, sizeof (tree));
+  n_phi_preds = last_basic_block;
 
   if (!expr_phi_insertion ((bitmap *)data, ei))
     goto cleanup;