--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/pr58145-1.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,36 @@
+/* PR tree-optimization/58145 */
+/* { dg-do compile { target { int32plus } } } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+struct S { unsigned int data : 32; };
+struct T { unsigned int data; };
+volatile struct S s2;
+
+void
+f1 (int val)
+{
+  struct S s = { .data = val };
+  *(volatile struct S *) 0x880000UL = s;
+}
+
+void
+f2 (int val)
+{
+  struct T t = { .data = val };
+  *(volatile struct T *) 0x880000UL = t;
+}
+
+void
+f3 (int val)
+{
+  *(volatile unsigned int *) 0x880000UL = val;
+}
+
+void
+f4 (int val)
+{
+  struct S s = { .data = val };
+  s2 = s;
+}
+
+/* { dg-final { scan-tree-dump-times " ={v} " 4 "optimized" } } */