Add Om1 lowering with no optimizations

crosstest/test_cast.cpp

+// This aims to test all the conversion bitcode instructions across
+// all PNaCl primitive data types.
+
+#include <stdint.h>
+#include "test_cast.h"
+
+template <typename FromType, typename ToType>
+ToType __attribute__((noinline)) cast(FromType a) {
+  return (ToType)a;
+}
+
+template <typename FromType, typename ToType>
+ToType __attribute__((noinline)) castBits(FromType a) {
+  return *(ToType *)&a;
+}
+
+// The purpose of the following sets of templates is to force
+// cast<A,B>() to be instantiated in the resulting bitcode file for
+// all <A,B>, so that they can be called from the driver.
+template <typename ToType> class Caster {
+  static ToType f(bool a) { return cast<bool, ToType>(a); }
+  static ToType f(int8_t a) { return cast<int8_t, ToType>(a); }
+  static ToType f(uint8_t a) { return cast<uint8_t, ToType>(a); }
+  static ToType f(int16_t a) { return cast<int16_t, ToType>(a); }
+  static ToType f(uint16_t a) { return cast<uint16_t, ToType>(a); }
+  static ToType f(int32_t a) { return cast<int32_t, ToType>(a); }
+  static ToType f(uint32_t a) { return cast<uint32_t, ToType>(a); }
+  static ToType f(int64_t a) { return cast<int64_t, ToType>(a); }
+  static ToType f(uint64_t a) { return cast<uint64_t, ToType>(a); }
+  static ToType f(float a) { return cast<float, ToType>(a); }
+  static ToType f(double a) { return cast<double, ToType>(a); }
+};
+
+// Comment out the definition of Caster<bool> because clang compiles
+// casts to bool using icmp instead of the desired cast instruction.
+// The corrected definitions are in test_cast_to_u1.ll.
+
+// template class Caster<bool>;
+
+template class Caster<int8_t>;
+template class Caster<uint8_t>;
+template class Caster<int16_t>;
+template class Caster<uint16_t>;
+template class Caster<int32_t>;
+template class Caster<uint32_t>;
+template class Caster<int64_t>;
+template class Caster<uint64_t>;
+template class Caster<float>;
+template class Caster<double>;
+
+// This function definition forces castBits<A,B>() to be instantiated
+// in the resulting bitcode file for the 4 relevant <A,B>
+// combinations, so that they can be called from the driver.
+double makeBitCasters() {
+  double Result = 0;
+  Result += castBits<uint32_t, float>(0);
+  Result += castBits<uint64_t, double>(0);
+  Result += castBits<float, uint32_t>(0);
+  Result += castBits<double, uint64_t>(0);
+  return Result;
+}