Subzero: Strength-reduce mul by certain constants.

crosstest/test_strengthreduce.cpp

+//===- subzero/crosstest/test_strengthreduce.cpp - Strength reduction -----===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Implementation for crosstesting strength reduction.
+//
+//===----------------------------------------------------------------------===//
+
+#include "test_strengthreduce.h"
+
+// TODO(stichnot): Extend to i16 and i8 types, and also test the
+// commutativity transformations.  This may require hand-generating
+// .ll files, because of C/C++ integer promotion rules for arithmetic,
+// and because clang prefers to do its own commutativity
+// transformation.
+
+#define X(constant, suffix)                                                    \
+  uint32_t multiplyByConst##suffix(uint32_t Val) {                             \
+    return Val * (uint32_t)constant;                                           \
+  }                                                                            \
+  int32_t multiplyByConst##suffix(int32_t Val) {                               \
+    return Val * (int32_t)constant;                                            \
+  }
+CONST_TABLE
+#undef X