Generate P/Invoke transitions for CoreRT.

This change adds support for CoreRT-style P/Invoke transitions
to RyuJIT. Instead of the usual inlined transition code, these
transitions are made up of calls to two new JIT helpers:

    PInvokeTransitionFrame frame; // opaque local
    CORINFO_HELP_INIT_PINVOKE_FRAME(&frame);
    ...
    CORINFO_HELP_JIT_PINVOKE_BEGIN(&frame);
    target(...);
    CORINFO_HELP_JIT_PINVOKE_END(&frame);
    ...

The preemptive mode constraints apply between calls to
JIT_PINVOKE_BEGIN and JIT_PINVOKE_END: no managed references
may be live only in registers and managed references may not
be manipulated.

0 files changed, 0 insertions, 0 deletions