The example Fibonacci is not responsive most of the times #23
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This comment was originally written by kand...@gmail.com Fibonacci grows exponentially as a geometric power, the difference between 30 and 50 is orders of magnitude, and thus of course you don't see the result because it takes a very long time to compute. Try learning how to open the Task Manager and checking the CPU usage or write a print statement to find out what fibonacci you are on. |
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This comment was originally written by drfibonacci@google.com Um, yes, the example code is the recursive algorithm, which blows up quickly for n>35. In fact, Google App Engine system status page uses this algorithm as a compact way to tax the CPU for measurement purposes. Personally, the example bothers me because it's too verbose. With Dart, you can easily compute the nth Fibonacci # in exactly 34 characters (granted, spacing is a bit arbitrary): f(n) => n<2 ? n : f(n-2) + f(n-1); Added Invalid label. |
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Here's a minimal repro that this CL fixes: `ui.dart` ```dart library dart.ui; import 'dart:ffi'; part 'foo.dart'; ``` `foo.dart` ```dart part of dart.ui; @Native<Void Function()>(symbol: 'foo_func', isLeaf: true) external void foo_func(); ``` When compiling with `compile_platform.dart` with `--target=dart2wasm`, the following error appears: ``` Unhandled exception: Verification error: Target=wasm, VerificationStage.afterModularTransformations: Invalid location with target 'wasm' on FunctionNode() (FunctionNode): RangeError (offset): Invalid value: Not in inclusive range 0..56: 91 Context: 'foo_func_$import'. Node: 'FunctionNode()'. #0 VerificationErrorListener.reportError (package:kernel/verifier.dart:81:5) #1 VerifyingVisitor.problem (package:kernel/verifier.dart:222:14) #2 VerifyingVisitor._getLocation (package:kernel/verifier.dart:1361:7) #3 VerifyingVisitor._hasLocation (package:kernel/verifier.dart:1370:26) #4 VerifyingVisitor.getSameLibraryLastSeenTreeNode (package:kernel/verifier.dart:1342:28) #5 VerifyingVisitor.localContext (package:kernel/verifier.dart:1382:24) #6 VerifyingVisitor.defaultDartType (package:kernel/verifier.dart:1491:41) #7 Visitor.visitVoidType (package:kernel/visitor.dart:1309:37) #8 VoidType.accept (package:kernel/ast.dart:11190:42) #9 FunctionNode.visitChildren (package:kernel/ast.dart:3919:16) #10 VerifyingVisitor.visitChildren (package:kernel/verifier.dart:259:10) #11 VerifyingVisitor.visitWithLocalScope (package:kernel/verifier.dart:266:5) #12 VerifyingVisitor.visitFunctionNode (package:kernel/verifier.dart:721:5) #13 FunctionNode.accept (package:kernel/ast.dart:3908:38) #14 VerifyingVisitor.visitProcedure (package:kernel/verifier.dart:620:19) #15 Procedure.accept (package:kernel/ast.dart:3311:40) #16 visitList (package:kernel/ast.dart:14488:14) #17 Library.visitChildren (package:kernel/ast.dart:591:5) #18 VerifyingVisitor.visitChildren (package:kernel/verifier.dart:259:10) #19 VerifyingVisitor.defaultTreeNode (package:kernel/verifier.dart:196:5) #20 TreeVisitor.visitLibrary (package:kernel/visitor.dart:503:35) #21 VerifyingVisitor.visitLibrary (package:kernel/verifier.dart:367:11) #22 Library.accept (package:kernel/ast.dart:577:38) #23 visitList (package:kernel/ast.dart:14488:14) #24 Component.visitChildren (package:kernel/ast.dart:14320:5) #25 VerifyingVisitor.visitChildren (package:kernel/verifier.dart:259:10) #26 VerifyingVisitor.visitComponent (package:kernel/verifier.dart:342:7) #27 Component.accept (package:kernel/ast.dart:14313:38) #28 VerifyingVisitor.check (package:kernel/verifier.dart:171:15) #29 verifyComponent (package:kernel/verifier.dart:69:20) ... ``` The issue seems to be that after doing this native transformation, the node's `fileUri` references the enclosing library (`ui.dart` above), but the `node.location` references the actual source file (`foo.dart` above) indirectly through `node.fileOffset`. This ends up being an issue when compiling the platform dill in Google3, but I didn't look into why `flutter build web --wasm` isn't broken. Internal bug: b/292172146 Change-Id: I2b8d7d215b2c36354860257ce651d50168e9523d Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/315360 Reviewed-by: Ömer Ağacan <omersa@google.com> Commit-Queue: Jia Hao Goh <jiahaog@google.com>
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This issue was originally filed by guilhermeorti...@gmail.com
What steps will reproduce the problem?
What is the expected output? What do you see instead?
I was expecting a numeric output generated by the function. Instead, the page freezes or crashes.
What version of the product are you using? On what operating system?
n/a. Google Chrome on Windows 7
Please provide any additional information below.
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