Right each `Pointer.fromFunction()` invocation will lead to creation of
a new ffi trampoline function & it's following JITed code. In AOT we
have exactly one ffi trampoline per target/native-signature/exceptional-return
combination.
=> This CL ensures we have only one such function.
Furthermore each `Pointer.fromFunction()` will currently perform 2
runtime calls in JIT: One to create a `Function` object, the other to
JIT that function & register callback metadata.
=> This CL ensures we won't do a runtime call to get a function, instead
do it at compile-time (as in AOT)
Furthermore we eagerly assign a callback-id to the unique/deduped ffi
trampoline callbacks. Only when the application requests a pointer, do
we populate metadata on the `Thread` object.
This CL doesn't (yet) change the fact that in JIT mode we have
isolate-specific jit trampolines (that will call now shared ffi trampoline
functions).
We also avoid baking in C++ runtime function pointers in generated
code. As a result we can now preserve ffi trampolines across AppJIT
serialization.
As a nice side-effect, we remove 100 lines of code.
TEST=ffi{,_2}/ffi_callback_unique_test
Issue https://github.com/dart-lang/sdk/issues/50611
Change-Id: I458831a47b041a088086f28f825de2a3849f6adc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/273420
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
Martin Kustermann
4be2981c2d