1 files changed, 21 insertions, 0 deletions
diff --git a/gcc/testsuite/gcc.dg/torture/tree-loop-1.c b/gcc/testsuite/gcc.dg/torture/tree-loop-1.c
new file mode 100644
index 00000000000..1d38691780a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/tree-loop-1.c
@@ -0,0 +1,21 @@
+/* PR tree-optimization/20640 */
+
+/* After unrolling the loop, we'd turn some conditional branches into
+   unconditional ones, but branch redirection would fail to compute
+   the PHI args for the PHI nodes in the replacement edge
+   destination, so they'd remain NULL causing crashes later on.  */
+
+/* { dg-do compile } */
+
+static int a = 0;
+extern int foo (void);
+extern int *bar (void) __attribute__ ((__const__));
+
+void
+test (int x)
+{
+  int b = 10;
+  while (foo () == -1 && *bar () == 4 && b > 0)
+    --b;
+  a = x;
+}