1. A computer-implemented method, comprising: prior to compilation of a program into machine code, generating directives about the program, the directives for directing compilation of the program into machine code by a just-in-time compiler; embedding the directives into a bytecode representation of the program, stored in a machine-readable medium, wherein at least a portion of the bytecode representation can be one-pass compiled into machine code by the just-in-time compiler directed by the embedded directives and compiling the at least a portion of the bytecode representation into machine code in one-pass with the just-in-time compiler using the embedded directives.
3. The computer-implemented method of claim 1 , wherein said prior to compilation of a program into machine code, generating directives about the program, the directives for directing compilation of the program into machine code by a just-in-time compiler, comprises: computing at least one of refined types, loop structure, value invariance, value liveness, register allocation, type profiles, execution counts, type estimates, profile estimates, inlining directives, optimistic value assertions, optimistic type assertions, and customization points for the program.