Introducing the llvm::JIT framework

The JIT class and its framework represent the older engine and are implemented by using different parts of the LLVM code generator. It will be removed after LLVM 3.5. Even though the engine is mostly target-independent, each target must implement the binary instruction emission step for its specific instructions.

Writing blobs to memory

The JIT class emits binary instructions by using JITCodeEmitter, a MachineCodeEmitter subclass. The MachineCodeEmitter class is used for machine code emission that is not related to the new Machine Code (MC) framework—even though it is old, it is still present to support the functionality of the JIT class. The limitations are that only a few targets are supported, and for the supported targets, not all target features are available.

The MachineCodeEmitter class has methods that facilitate the following tasks:

• To allocate space (allocateSpace()) for the current function to be emitted
• To write binary blobs to memory buffers...