Adding the new architecture to the Triple class
An instance of the Triple class represents the target platform LLVM is producing code for. To support a new architecture, the first task is to extend the Triple class. In the llvm/include/llvm/ADT/Triple.h file, you add a member to the ArchType enumeration and a new predicate:
class Triple {
public:
  enum ArchType {
  // Many more members
    m88k,           // M88000 (big endian): m88k
  };
  /// Tests whether the target is M88k.
  bool isM88k() const {
    return getArch() == Triple::m88k;
  }
// Many more methods
};
Inside the llvm/lib/Support/Triple.cpp file, there are numerous methods that use the ArchType enumeration. You need to extend all of them; for example, in the getArchTypeName() method, you need to add a new case statement:
  switch (Kind) {
// Many...
