Unties the backend from changes to FFI_TYPE_* constants, and allows
compilation to succeed after the addition of FFI_TYPE_COMPLEX.
Delete the hand-written unwind info.
Move everything into sysv.S, removing win32.S and freebsd.S.
Handle all abis with a single ffi_closure_inner function.
Move complexity of the raw THISCALL trampoline into assembly
instead of the trampoline itself.
Only push the context for the REGISTER abi; let the rest
receive it in a register.
Decouple the assembly from FFI_TYPE_*. Merge prep_args with ffi_call,
passing the frame and the stack to the assembly.
Note that this patch isn't really standalone, as this breaks closures.
The x86_64 unix port only handles one ABI; don't define all of the
other symbols. The UNIX64 symbol retains the same value.
The i386 ports ought to have the same symbols, even if we can't yet
unify the values without incrementing the libffi soname.
Dumps all of the hand-coded unwind info for gas generated. Move jump
table data into .rodata. Adjust ffi_call_unix64 to load the static
chain. Split out sse portions of ffi_closure_unix64 to
ffi_closure_unix64_sse rather than test cif->flags at runtime.
A "ffi_go_closure" is intended to be compatible with the
function descriptors used by Go, and ffi_call_go sets up
the static chain parameter for calling a Go function.
The entry points are disabled when a backend has not been
updated, much like we do for "normal" closures.
Richard Henderson