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Fix: Check handle contents for Smi. Closes: https://github.com/flutter/flutter/issues/112726 Orignal CL description: Makes `Dart_Handle` FFI returns behave as the following snippet: ``` Dart_Handle ExampleSnippet() { Dart_Handle result = ...; if (Dart_IsError(result)) { Dart_PropagateError(result); } return result; } ``` Also makes FFI consistent with Dart_NativeFunctions, which will automatically throw upon return if Dart_SetReturnValue set the result to an error. `UnhandledExceptions` cannot flow out into Dart generated code. So, the implementation needs to be in `FfiCallInstr::EmitNativeCode`. Using `Dart_IsError` is slow compared to a machine code class id check. So, we should do the handle unwrapping and class id check in machine code. Unwrapping Handles in machine code is only safe when the GC is guaranteed to not run: Either (1) in `kThreadInGenerated`, or (2) in `kThreadInNative`, but only when transitioned into safepoint. So, the handle cannot be unwrapped immediately after the FFI call in machine code. We first need to transition back to generated. This means we need to transition again to native to do the actual `Dart_PropagateError` call. We can do so without the stub in JIT because we never return with normal control flow. Performance impact of this change is within benchmark noise in both JIT and AOT. Size impact is 42 bytes on x64, which is 10% in AOT and 12% in JIT. For more numbers see: go/dart-ffi-handle-error TEST=runtime/bin/ffi_test/ffi_test_functions_vmspecific.cc TEST=tests/ffi/vmspecific_handle_test.dart Closes: https://github.com/dart-lang/sdk/issues/49936 Change-Id: Id8edfd841a7d6246438386007d83747868a0a151 Cq-Include-Trybots: luci.dart.try:vm-canary-linux-debug-try,vm-ffi-android-debug-arm64c-try,vm-ffi-android-debug-arm-try,vm-kernel-gcc-linux-try,vm-kernel-linux-debug-x64-try,vm-kernel-linux-debug-x64c-try,vm-kernel-msvc-windows-try,vm-kernel-optcounter-threshold-linux-release-x64-try,vm-kernel-precomp-asan-linux-release-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-reload-linux-debug-x64-try,vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-tsan-linux-release-x64-try,vm-kernel-win-debug-x64-try,vm-kernel-win-debug-ia32-try,vm-precomp-ffi-qemu-linux-release-arm-try,vm-precomp-ffi-qemu-linux-release-riscv64-try,vm-kernel-linux-debug-ia32-try,vm-kernel-mac-release-arm64-try,vm-kernel-precomp-win-debug-x64c-try Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/262342 Reviewed-by: Martin Kustermann <kustermann@google.com> Auto-Submit: Daco Harkes <dacoharkes@google.com> Commit-Queue: Daco Harkes <dacoharkes@google.com> |
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