Add a simple helper function to create a 64-bit integer.

[zturner]

Summary

Add a function to combine two 32-bit integers into a 64-bit integer. There are no calls to this function yet, although a subsequent change will add some in LLDB.

[rnk]

lgtm

I'll go ahead and land this for you.

[rnk]

Closed by commit rL209777 (authored by @rnk).

llvm/trunk/include/llvm/Support/MathExtras.h

inline uint32_t Hi_32(uint64_t Value) {
   return static_cast<uint32_t>(Value >> 32);
 }
 
 /// Lo_32 - This function returns the low 32 bits of a 64 bit value.
 inline uint32_t Lo_32(uint64_t Value) {
   return static_cast<uint32_t>(Value);
 }
 
+/// Make_64 - This functions makes a 64-bit integer from a high / low pair of
+///           32-bit integers.
+inline uint64_t Make_64(uint32_t High, uint32_t Low) {
+  return ((uint64_t)High << 32) | (uint64_t)Low;
+}
+
 /// isInt - Checks if an integer fits into the given bit width.
 template<unsigned N>
 inline bool isInt(int64_t x) {
   return N >= 64 || (-(INT64_C(1)<<(N-1)) <= x && x < (INT64_C(1)<<(N-1)));
 }
 // Template specializations to get better code for common cases.
 template<>
 inline bool isInt<8>(int64_t x) {