--- /dev/null
+/* PR middle-end/36106 */
+/* { dg-options "-O2" } */
+/* { dg-options "-O2 -mieee" { target alpha*-*-* } } */
+/* { dg-options "-O2 -march=i586" { target { { i?86-*-* x86_64-*-* } && ilp32 } } } */
+
+#ifdef __i386__
+# include "cpuid.h"
+#endif
+
+extern void abort (void);
+
+union { unsigned long long l; double d; } u = { .l = 0x7ff0000000072301ULL };
+
+int __attribute__((noinline))
+do_test (void)
+{
+#pragma omp atomic
+ u.d += 1.0L;
+ return 0;
+}
+
+int
+main (void)
+{
+#ifdef __i386__
+ unsigned int eax, ebx, ecx, edx;
+
+ if (!__get_cpuid (1, &eax, &ebx, &ecx, &edx))
+ return 0;
+
+ if (!(edx & bit_CMPXCHG8B))
+ return 0;
+#endif
+
+ do_test ();
+
+ return 0;
+}