Subzero: lower the rest of the atomic operations.

crosstest/test_sync_atomic.cpp

Index: crosstest/test_sync_atomic.cpp
diff --git a/crosstest/test_sync_atomic.cpp b/crosstest/test_sync_atomic.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..9f4cc610e9466a8fe82b37908efc2cc996287280
--- /dev/null
+++ b/crosstest/test_sync_atomic.cpp
@@ -0,0 +1,52 @@
+// This aims to test that all the atomic RMW instructions and compare and swap
+// work across the allowed atomic types. This uses the __sync_* builtins
+// to test the atomic operations.
+
+#include <stdint.h>
+
+#include <cstdlib>
+
+#include "test_sync_atomic.h"
+
+#define X(inst, type)                                                   \
+  type test_##inst(bool fetch_first, volatile type *ptr, type a) {      \
+    if (fetch_first) {                                                  \
+      return __sync_fetch_and_##inst(ptr, a);                           \
+    } else {                                                            \
+      return __sync_##inst##_and_fetch(ptr, a);                         \
+    }                                                                   \
+  }                                                                     \
+  type test_alloca_##inst(bool fetch, volatile type *ptr, type a) {     \
+    const size_t buf_size = 8;                                          \
+    type buf[buf_size];                                                 \
+    for (size_t i = 0; i < buf_size; ++i) {                             \
+      if (fetch) {                                                      \
+        buf[i] = __sync_fetch_and_##inst(ptr, a);                       \
+      } else {                                                          \
+        buf[i] = __sync_##inst##_and_fetch(ptr, a);                     \
+      }                                                                 \
+    }                                                                   \
+    type sum = 0;                                                       \
+    for (size_t i = 0; i < buf_size; ++i) {                             \
+      sum += buf[i];                                                    \
+    }                                                                   \
+    return sum;                                                         \
+  }                                                                     \
+  type test_const_##inst(bool fetch, volatile type *ptr, type ign) {    \
+    if (fetch) {                                                        \
+      return __sync_fetch_and_##inst(ptr, 42);                          \
+    } else {                                                            \
+      return __sync_##inst##_and_fetch(ptr, 99);                        \
+    }                                                                   \
+  }
+
+FOR_ALL_RMWOP_TYPES(X)
+#undef X
+
+#define X(type)                                                          \
+  type test_val_cmp_swap(volatile type *ptr, type oldval, type newval) { \
+    return __sync_val_compare_and_swap(ptr, oldval, newval);             \
+  }
+
+ATOMIC_TYPE_TABLE
+#undef X