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[dart2wasm] Better debugging support #55763

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[dart2wasm] Better debugging support#55763
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area-dart2wasmIssues for the dart2wasm compiler.

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@felix-ht
felix-ht
opened on May 17, 2024

Add debugging capabilities to the dart tooling so we can easily debug wasm code, from within our IDEs.

There doesn't seem to be a good way to debug dart code that has been complied to wasm. I can set break points in the complied wasm code, but because there are no source maps this is quite useless, so i am back to debugging with strings.

Activity

  1. lrhn
    added
    area-dart2wasmIssues for the dart2wasm compiler.
    on May 19, 2024

  2. mkustermann commented on May 21, 2024

    @mkustermann
    mkustermann
    on May 21, 2024
    Member

    For fast turnaround during development of apps in Dart for web we recommend to use DDC. Dart2wasm is (similar to dart2js) for deploying apps.

    That being said if one has to debug issues that only happen with dart2wasm compiled apps, I can recommend using the -O0 flag (flutter build web --wasm -O0 / dart compile wasm -O0 ) which will turn off optimizations and keeps static symbol names, does not minify runtime type names, etc.

    Additionally we do plan on offering source maps support (@osa1 is working on it atm)

  3. felix-ht commented on May 21, 2024

    @felix-ht
    felix-ht
    on May 21, 2024
    Author

    That was exactly the issue, JS is running fine, but i got lots of issues after compling to wasm.

    Thanks for the info on the flags!

  4. mkustermann commented on May 21, 2024

    @mkustermann
    mkustermann
    on May 21, 2024
    Member

    That was exactly the issue, JS is running fine, but i got lots of issues after compling to wasm.

    If you run into any issues in our compilers, libraries etc, please don't hesitate to reach out!

  5. uldall commented on May 24, 2024

    @uldall
    uldall
    on May 24, 2024

    I am trying to build our Flutter application with wasm support:
    $ flutter build web --wasm -O0

    I am however getting this error:

    Target dart2wasm failed: ProcessException: Process exited abnormally with exit code 64:
Unhandled exception:
Constant InstanceConstant(const _FfiAbiSpecificMapping{_FfiAbiSpecificMapping.nativeTypes: const <Type?>[Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32,
Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32]}) references field _FfiAbiSpecificMapping.nativeTypes which is not retained
#0      _TreeShakerConstantVisitor.visitInstanceConstant.<anonymous closure> (package:vm/transformations/type_flow/transformer.dart:2274)
#1      _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:633)
#2      _TreeShakerConstantVisitor.visitInstanceConstant (package:vm/transformations/type_flow/transformer.dart:2272)
#3      InstanceConstant.accept (package:kernel/ast.dart:13982)
#4      _TreeShakerConstantVisitor.analyzeConstant (package:vm/transformations/type_flow/transformer.dart:2207)
#5      _TreeShakerConstantVisitor.visitInstanceConstant.<anonymous closure> (package:vm/transformations/type_flow/transformer.dart:2277)
#6      _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:633)
#7      _TreeShakerConstantVisitor.visitInstanceConstant (package:vm/transformations/type_flow/transformer.dart:2272)
#8      InstanceConstant.accept (package:kernel/ast.dart:13982)
#9      _TreeShakerConstantVisitor.analyzeConstant (package:vm/transformations/type_flow/transformer.dart:2207)
#10     _TreeShakerPass1.visitConstant (package:vm/transformations/type_flow/transformer.dart:1580)
#11     ConstantExpression.transformOrRemoveChildren (package:kernel/ast.dart:8651)
#12     RemovingTransformer.defaultTreeNode (package:kernel/visitor.dart:2164)
#13     TreeVisitor1Default.defaultExpression (package:kernel/visitor.dart:739)
#14     ExpressionVisitor1DefaultMixin.visitConstantExpression (package:kernel/visitor.dart:2368)
#15     ConstantExpression.accept1 (package:kernel/ast.dart:8635)
#16     RemovingTransformer.transformOrRemove (package:kernel/visitor.dart:1917)
#17     RemovingTransformer.transformList (package:kernel/visitor.dart:2141)
#18     RemovingTransformer.transformExpressionList (package:kernel/visitor.dart:2067)
#19     TreeShaker.addClassUsedInType (package:vm/transformations/type_flow/transformer.dart:897)
#20     _TreeShakerTypeVisitor.visitInterfaceType (package:vm/transformations/type_flow/transformer.dart:1120)
#21     InterfaceType.accept (package:kernel/ast.dart:11473)
#22     visitList (package:kernel/ast.dart:14751)
#23     FunctionType.visitChildren (package:kernel/ast.dart:11583)
#24     RecursiveVisitor.defaultNode (package:kernel/visitor.dart:1725)
#25     VisitorDefaultMixin.visitSupertype (package:kernel/visitor.dart:1501)
#26     DartTypeVisitorDefaultMixin.visitInvalidType (package:kernel/visitor.dart:781)
#27     FunctionType.accept (package:kernel/ast.dart:11574)
#28     visitList (package:kernel/ast.dart:14751)
#29     InterfaceType.visitChildren (package:kernel/ast.dart:11482)
#30     _TreeShakerTypeVisitor.visitInterfaceType (package:vm/transformations/type_flow/transformer.dart:1121)
#31     InterfaceType.accept (package:kernel/ast.dart:11473)
#32     visitList (package:kernel/ast.dart:14751)
#33     InterfaceType.visitChildren (package:kernel/ast.dart:11482)
#34     _TreeShakerTypeVisitor.visitInterfaceType (package:vm/transformations/type_flow/transformer.dart:1121)
#35     InterfaceType.accept (package:kernel/ast.dart:11473)
#36     _TreeShakerPass1.visitDartType (package:vm/transformations/type_flow/transformer.dart:1269)
#37     VariableDeclaration.transformOrRemoveChildren (package:kernel/ast.dart:10745)
#38     RemovingTransformer.defaultTreeNode (package:kernel/visitor.dart:2164)
#39     TreeVisitor1Default.defaultExpression (package:kernel/visitor.dart:739)
#40     StatementVisitor1DefaultMixin.visitVariableDeclaration (package:kernel/visitor.dart:2597)
#41     VariableDeclaration.accept1 (package:kernel/ast.dart:10723)
#42     RemovingTransformer.transformOrRemove (package:kernel/visitor.dart:1917)
#43     RemovingTransformer.transformList (package:kernel/visitor.dart:2141)
#44     RemovingTransformer.transformStatementList (package:kernel/visitor.dart:2095)
#45     AssertBlock.transformOrRemoveChildren (package:kernel/ast.dart:9239)
#46     RemovingTransformer.defaultTreeNode (package:kernel/visitor.dart:2164)
#47     TreeVisitor1Default.defaultExpression (package:kernel/visitor.dart:739)
#48     StatementVisitor1DefaultMixin.visitBlock (package:kernel/visitor.dart:2546)
#49     Block.accept1 (package:kernel/ast.dart:9178)
#50     RemovingTransformer.transform (package:kernel/visitor.dart:1881)
#51     BlockExpression.transformOrRemoveChildren (package:kernel/ast.dart:8781)
#52     RemovingTransformer.defaultTreeNode (package:kernel/visitor.dart:2164)
#53     TreeVisitor1Default.defaultExpression (package:kernel/visitor.dart:739)
#54     ExpressionVisitor1DefaultMixin.visitBlockExpression (package:kernel/visitor.dart:2402)
#55     BlockExpression.accept1 (package:kernel/ast.dart:8763)
#56     RemovingTransformer.transformOrRemove (package:kernel/visitor.dart:1917)
#57     RemovingTransformer.transformOrRemoveExpression (package:kernel/visitor.dart:1890)
#58     Field.transformOrRemoveChildren (package:kernel/ast.dart:2549)
#59     _TreeShakerPass1.visitField (package:vm/transformations/type_flow/transformer.dart:1341)
#60     Field.accept1 (package:kernel/ast.dart:2520)
#61     RemovingTransformer.transformOrRemove (package:kernel/visitor.dart:1917)
#62     RemovingTransformer.transformList (package:kernel/visitor.dart:2141)
#63     RemovingTransformer.transformFieldList (package:kernel/visitor.dart:2041)
#64     _TreeShakerPass1.visitClass (package:vm/transformations/type_flow/transformer.dart:1307)
#65     Class.accept1 (package:kernel/ast.dart:1476)
#66     RemovingTransformer.transformOrRemove (package:kernel/visitor.dart:1917)
#67     RemovingTransformer.transformList (package:kernel/visitor.dart:2141)
#68     RemovingTransformer.transformClassList (package:kernel/visitor.dart:1996)
#69     Library.transformOrRemoveChildren (package:kernel/ast.dart:626)
#70     RemovingTransformer.defaultTreeNode (package:kernel/visitor.dart:2164)
#71     TreeVisitor1DefaultMixin.visitLibrary (package:kernel/visitor.dart:680)
#72     Library.accept1 (package:kernel/ast.dart:592)
#73     RemovingTransformer.transformOrRemove (package:kernel/visitor.dart:1917)
#74     RemovingTransformer.transformList (package:kernel/visitor.dart:2141)
#75     RemovingTransformer.transformLibraryList (package:kernel/visitor.dart:1960)
#76     Component.transformOrRemoveChildren (package:kernel/ast.dart:14617)
#77     _TreeShakerPass1.transformComponent (package:vm/transformations/type_flow/transformer.dart:1178)
#78     TreeShaker.transformComponent (package:vm/transformations/type_flow/transformer.dart:848)
#79     transformComponent (package:vm/transformations/type_flow/transformer.dart:136)
#80     compileToModule (package:dart2wasm/compile.dart:166)
<asynchronous suspension>
#81     generateWasm (package:dart2wasm/generate_wasm.dart:23)
<asynchronous suspension>
#82     main (file:///b/s/w/ir/x/w/sdk/pkg/dart2wasm/bin/dart2wasm.dart:10)
<asynchronous suspension>
  Command: /home/cup/snap/flutter/common/flutter/bin/cache/dart-sdk/bin/dart compile wasm --packages=.dart_tool/package_config.json
  --extra-compiler-option=--dart-sdk=/home/cup/snap/flutter/common/flutter/bin/cache/dart-sdk
  --extra-compiler-option=--platform=/home/cup/snap/flutter/common/flutter/bin/cache/flutter_web_sdk/kernel/dart2wasm_platform.dill
  --extra-compiler-option=--delete-tostring-package-uri=dart:ui --extra-compiler-option=--delete-tostring-package-uri=package:flutter --extra-compiler-option=--import-shared-memory
  --extra-compiler-option=--shared-memory-max-pages=32768 -Ddart.vm.product=true
  -DFLUTTER_WEB_CANVASKIT_URL=https://www.gstatic.com/flutter-canvaskit/4ab44247522322094511fbc271fb828bb31bd072/ -DFLUTTER_WEB_AUTO_DETECT=false -DFLUTTER_WEB_USE_SKIA=false
  -DFLUTTER_WEB_USE_SKWASM=true --extra-compiler-option=--depfile=/media/cup/data/git/zoolander/.dart_tool/flutter_build/ce5be2d647610cff5873f737118dcfff/dart2wasm.d -O0 --no-name-section -o
  /media/cup/data/git/zoolander/.dart_tool/flutter_build/ce5be2d647610cff5873f737118dcfff/main.dart.wasm
  /media/cup/data/git/zoolander/.dart_tool/flutter_build/ce5be2d647610cff5873f737118dcfff/main.dart
#0      RunResult.throwException (package:flutter_tools/src/base/process.dart:122:5)
#1      _DefaultProcessUtils.run (package:flutter_tools/src/base/process.dart:318:19)
<asynchronous suspension>
#2      Dart2WasmTarget.build (package:flutter_tools/src/build_system/targets/web.dart:329:5)
<asynchronous suspension>
#3      _BuildInstance._invokeInternal (package:flutter_tools/src/build_system/build_system.dart:867:9)
<asynchronous suspension>
#4      Future.wait.<anonymous closure> (dart:async/future.dart:534:21)
<asynchronous suspension>
#5      _BuildInstance.invokeTarget (package:flutter_tools/src/build_system/build_system.dart:805:32)
<asynchronous suspension>
#6      Future.wait.<anonymous closure> (dart:async/future.dart:534:21)
<asynchronous suspension>
#7      _BuildInstance.invokeTarget (package:flutter_tools/src/build_system/build_system.dart:805:32)
<asynchronous suspension>
#8      FlutterBuildSystem.build (package:flutter_tools/src/build_system/build_system.dart:634:16)
<asynchronous suspension>
#9      WebBuilder.buildWeb (package:flutter_tools/src/web/compile.dart:92:34)
<asynchronous suspension>
#10     BuildWebCommand.runCommand (package:flutter_tools/src/commands/build_web.dart:230:5)
<asynchronous suspension>
#11     FlutterCommand.run.<anonymous closure> (package:flutter_tools/src/runner/flutter_command.dart:1396:27)
<asynchronous suspension>
#12     AppContext.run.<anonymous closure> (package:flutter_tools/src/base/context.dart:153:19)
<asynchronous suspension>
#13     CommandRunner.runCommand (package:args/command_runner.dart:212:13)
<asynchronous suspension>
#14     FlutterCommandRunner.runCommand.<anonymous closure> (package:flutter_tools/src/runner/flutter_command_runner.dart:372:9)
<asynchronous suspension>
#15     AppContext.run.<anonymous closure> (package:flutter_tools/src/base/context.dart:153:19)
<asynchronous suspension>
#16     FlutterCommandRunner.runCommand (package:flutter_tools/src/runner/flutter_command_runner.dart:308:5)
<asynchronous suspension>
#17     run.<anonymous closure>.<anonymous closure> (package:flutter_tools/runner.dart:130:9)
<asynchronous suspension>
#18     AppContext.run.<anonymous closure> (package:flutter_tools/src/base/context.dart:153:19)
<asynchronous suspension>
#19     main (package:flutter_tools/executable.dart:93:3)
<asynchronous suspension>

Compiling lib/main.dart for the Web...                             43.2s
Error: Failed to compile application for the Web.

    Any ideas on how I can debug this?

  6. mkustermann commented on May 29, 2024

    @mkustermann
    mkustermann
    on May 29, 2024
    Member

    @uldall Right now dart:ffi is not really supported in dart2wasm. It was somewhat available but not entirely functional. After cl/368343 lands we'll report an error when user code imports dart:ffi. dart:ffi support for the web is tracked at #46690

  7. mkustermann commented on May 29, 2024

    @mkustermann
    mkustermann
    on May 29, 2024
    Member

    I'm going to close this in favor of the older #55229.

  8. mkustermann
    closed this as completedon May 29, 2024
  9. copybara-service
    added a commit that references this issue on Jul 19, 2024

    [beta] [dart2wasm] Generate source maps

    e20dc20
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