4 files changed, 43 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ac65b1c..0fc87d2 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-11-30  Bin Cheng  <bin.cheng@arm.com>
+
+	PR tree-optimization/78574
+	* tree-ssa-loop-ivopts.c (find_deriving_biv_for_expr): Skip loop
+	header PHI that doesn't define biv.
+
 2016-11-30  Jakub Jelinek  <jakub@redhat.com>
 
 	* emit-rtl.c (verify_insn_sharing): Call verify_rtx_sharing instead of
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 5aff606..eac361b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-11-30  Bin Cheng  <bin.cheng@arm.com>
+
+	PR tree-optimization/78574
+	* gcc.c-torture/compile/pr78574.c: New test.
+
 2016-11-30  Andre Vehreschild  <vehre@gcc.gnu.org>
 
 	* caf/single.c (_gfortran_caf_is_present): Prevent fallthrough
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr78574.c b/gcc/testsuite/gcc.c-torture/compile/pr78574.c
new file mode 100644
index 0000000..8c91d1e
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr78574.c
@@ -0,0 +1,27 @@
+/* PR tree-optimization/78574 */
+
+int a, d, f, g;
+int b[1];
+short h;
+int main() {
+  long j;
+  int k, i;
+  for (; j; j++) {
+    i = 0;
+    for (; i < 6; i++) {
+      int l = a, m = d || g;
+    L:
+      l ^ m | a;
+    }
+    b[j + 1] = 2;
+    ++k;
+    for (; g; g++) {
+      d ^= h;
+      if (f)
+        for (;;)
+          ;
+    }
+  }
+  if (k)
+    goto L;
+}
diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c
index 5c667a2..00b287a 100644
--- a/gcc/tree-ssa-loop-ivopts.c
+++ b/gcc/tree-ssa-loop-ivopts.c
@@ -1853,6 +1853,11 @@ find_deriving_biv_for_expr (struct ivopts_data *data, tree expr)
     {
       ssa_op_iter iter;
       use_operand_p use_p;
+      basic_block phi_bb = gimple_bb (phi);
+
+      /* Skip loop header PHI that doesn't define biv.  */
+      if (phi_bb->loop_father == data->current_loop)
+	return NULL;
 
       if (virtual_operand_p (gimple_phi_result (phi)))
 	return NULL;