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[vm/ffi] Struct and Union constructors fromTypedList #53418

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dcharkes opened this issue Sep 4, 2023 · 2 comments
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[vm/ffi] Struct and Union constructors fromTypedList #53418

dcharkes opened this issue Sep 4, 2023 · 2 comments
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area-vm Use area-vm for VM related issues, including code coverage, and the AOT and JIT backends. library-ffi P3 A lower priority bug or feature request triaged Issue has been triaged by sub team type-enhancement A request for a change that isn't a bug

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@dcharkes
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dcharkes commented Sep 4, 2023

If a developer happens to have a typed data that contains a struct that is laid out in memory according to the C ABI, then it would be useful to have a constructor on the struct subtype that takes a typed data.

Currently we have a hidden constructor #fromTypedDataBase that either takes a Pointer or a typed data. The Pointer can already be used via the .ref extension method.

Possible design:

final class MyStruct extends Struct {
  @Int8()
  external int a0;

  external Pointer<Int8> a1;

  external factory MyStruct.fromTypedList(Uint8List typedList);
}

The CFE would rewrite the body to the already existing #fromTypedDataBase.

Context: dart-lang/native#926

@dcharkes dcharkes added area-vm Use area-vm for VM related issues, including code coverage, and the AOT and JIT backends. library-ffi labels Sep 4, 2023
@dcharkes
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dcharkes commented Sep 4, 2023

Somewhat related issue:

@a-siva a-siva added the type-enhancement A request for a change that isn't a bug label Oct 12, 2023
@a-siva a-siva added P3 A lower priority bug or feature request triaged Issue has been triaged by sub team labels Nov 30, 2023
@dcharkes
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dcharkes commented Dec 4, 2023

Possible API design: #45697 (comment)

copybara-service bot pushed a commit that referenced this issue Jan 30, 2024
This reverts commit c2e15cf.

Reason for revert: #54754
Version skew somewhere in the analyzer/dartdoc/flutter combination.
We need to land the fix inside ffi_verifier.dart first, and then
reland the API docs that trigger the code path in the analyzer
that throws the exception.

Original change's description:
> [vm/ffi] Introduce `Struct.create` and `Union.create`
>
> Structs and unions can now be created from an existing typed data
> with the new `create` methods.
>
> The typed data argument to these `create` methods is optional. If
> the typed data argument is omitted, a new typed data of the right
> size will be allocated.
>
> Compound field reads and writes are unchecked. (These are
> TypedDataBase loads and stores, rather than TypedData loads and stores.
> And Pointers have no byte length.) Therefore the `create` method taking
> existing TypedData objects check whether the length in bytes it at
> least the size of the compound.
>
> TEST=pkg/analyzer/test/src/diagnostics/creation_of_struct_or_union_test.dart
> TEST=pkg/vm/testcases/transformations/ffi/struct_typed_data.dart
> TEST=tests/ffi/structs_typed_data_test.dart
> TEST=tests/ffi/vmspecific_static_checks_test.dart
>
> Closes: #45697
> Closes: #53418
>
> Change-Id: If12c56106c7ca56611bccfacbc1c680c2d4ce407
> CoreLibraryReviewExempt: FFI is a VM and WASM only feature.
> Cq-Include-Trybots: luci.dart.try:vm-aot-android-release-arm64c-try,vm-aot-android-release-arm_x64-try,vm-aot-linux-debug-x64-try,vm-aot-linux-debug-x64c-try,vm-aot-mac-release-arm64-try,vm-aot-mac-release-x64-try,vm-aot-obfuscate-linux-release-x64-try,vm-aot-optimization-level-linux-release-x64-try,vm-aot-win-debug-arm64-try,vm-aot-win-debug-x64c-try,vm-aot-win-release-x64-try,vm-appjit-linux-debug-x64-try,vm-asan-linux-release-x64-try,vm-checked-mac-release-arm64-try,vm-eager-optimization-linux-release-ia32-try,vm-eager-optimization-linux-release-x64-try,vm-ffi-android-debug-arm-try,vm-ffi-android-debug-arm64c-try,vm-ffi-qemu-linux-release-arm-try,vm-ffi-qemu-linux-release-riscv64-try,vm-fuchsia-release-x64-try,vm-kernel-linux-debug-x64-try,vm-kernel-precomp-linux-release-x64-try,vm-linux-debug-ia32-try,vm-linux-debug-x64-try,vm-linux-debug-x64c-try,vm-mac-debug-arm64-try,vm-mac-debug-x64-try,vm-msan-linux-release-x64-try,vm-reload-linux-debug-x64-try,vm-reload-rollback-linux-debug-x64-try,vm-ubsan-linux-release-x64-try,vm-win-debug-arm64-try,vm-win-debug-x64-try,vm-win-debug-x64c-try,vm-win-release-ia32-try
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/342763
> Commit-Queue: Daco Harkes <dacoharkes@google.com>
> Reviewed-by: Johnni Winther <johnniwinther@google.com>
> Reviewed-by: Lasse Nielsen <lrn@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>

Change-Id: I285dc39946b5659219b37a1d8f10de479133957e
Cq-Include-Trybots: luci.dart.try:vm-aot-android-release-arm64c-try,vm-aot-android-release-arm_x64-try,vm-aot-linux-debug-x64-try,vm-aot-linux-debug-x64c-try,vm-aot-mac-release-arm64-try,vm-aot-mac-release-x64-try,vm-aot-obfuscate-linux-release-x64-try,vm-aot-optimization-level-linux-release-x64-try,vm-aot-win-debug-arm64-try,vm-aot-win-debug-x64c-try,vm-aot-win-release-x64-try,vm-appjit-linux-debug-x64-try,vm-asan-linux-release-x64-try,vm-checked-mac-release-arm64-try,vm-eager-optimization-linux-release-ia32-try,vm-eager-optimization-linux-release-x64-try,vm-ffi-android-debug-arm-try,vm-ffi-android-debug-arm64c-try,vm-ffi-qemu-linux-release-arm-try,vm-ffi-qemu-linux-release-riscv64-try,vm-fuchsia-release-x64-try,vm-kernel-linux-debug-x64-try,vm-kernel-precomp-linux-release-x64-try,vm-linux-debug-ia32-try,vm-linux-debug-x64-try,vm-linux-debug-x64c-try,vm-mac-debug-arm64-try,vm-mac-debug-x64-try,vm-msan-linux-release-x64-try,vm-reload-linux-debug-x64-try,vm-reload-rollback-linux-debug-x64-try,vm-ubsan-linux-release-x64-try,vm-win-debug-arm64-try,vm-win-debug-x64-try,vm-win-debug-x64c-try,vm-win-release-ia32-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/349061
Commit-Queue: Daco Harkes <dacoharkes@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Zach Anderson <zra@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
@dcharkes dcharkes reopened this Jan 30, 2024
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area-vm Use area-vm for VM related issues, including code coverage, and the AOT and JIT backends. library-ffi P3 A lower priority bug or feature request triaged Issue has been triaged by sub team type-enhancement A request for a change that isn't a bug
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