Lower bitmanip intrinsics, assuming absence of BMI/SSE4.2 for now.

crosstest/test_bitmanip.cpp

+//===- subzero/crosstest/test_bitmanip.cpp - Implementation for tests. ----===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This aims to test that all the bit manipulation intrinsics work, via
+// cross-testing. This calls wrappers (my_{ctlz,cttz,ctpop} around the
+// intrinsics (llvm.{ctlz,cttz,ctpop}.*).
+//===----------------------------------------------------------------------===//
+
+#include <stdint.h>
+
+#include <cstdlib>
+
+#include "test_bitmanip.h"
+
+#define X(inst, type)                                                          \
+  type test_##inst(type a) { return my_##inst(a); }                            \
+  type test_alloca_##inst(type a) {                                            \
+    const size_t buf_size = 8;                                                 \
+    type buf[buf_size];                                                        \
+    for (size_t i = 0; i < buf_size; ++i) {                                    \
+      buf[i] = my_##inst(a);                                                   \
+    }                                                                          \
+    type sum = 0;                                                              \
+    for (size_t i = 0; i < buf_size; ++i) {                                    \
+      sum += buf[i];                                                           \
+    }                                                                          \
+    return sum;                                                                \
+  }                                                                            \
+  type test_const_##inst(type ignored) {                                       \
+    return my_##inst(static_cast<type>(0x12340));                              \
+  }
+
+FOR_ALL_BMI_OP_TYPES(X)
+#undef X