1 files changed, 43 insertions, 0 deletions
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr21559.c b/gcc/testsuite/gcc.dg/tree-ssa/pr21559.c
new file mode 100644
index 000000000..34f4a01db
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr21559.c
@@ -0,0 +1,43 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-vrp1-details" } */
+
+static int blocksize = 4096;
+
+int bar (int);
+
+void foo (void)
+{
+  int toread;
+  int bytes;
+  static char eof_reached = 0;
+
+  toread = blocksize;
+  bytes = 1;
+
+  while (toread != 0)
+    {
+      bytes = bar (toread);
+      if (bytes <= 0)
+        {
+          if (bytes < 0)
+            continue;
+          break;
+        }
+      toread -= bytes;
+    }
+
+  if (bytes == 0)
+    eof_reached = 1;
+}
+
+
+/* First, we should simplify the bits < 0 test within the loop.  */
+/* { dg-final { scan-tree-dump-times "Simplified relational" 1 "vrp1" } } */
+
+/* Second, we should thread the edge out of the loop via the break
+   statement.  We also realize that the final bytes == 0 test is useless,
+   and thread over it.  */
+/* { dg-final { scan-tree-dump-times "Threaded jump" 3 "vrp1" } } */
+
+/* { dg-final { cleanup-tree-dump "vrp1" } } */
+