KAnnotator : Inferring Type Information from Java Byte Codes

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KAnnotator : Inferring Type Information from Java Byte Codes. Alexey Sedunov Andrey Breslav Svetlana Isakova Evgeny Gerashchenko. JetBrains , s. r. o. 2013. Annotation Inference. Several languages on the Java platform refine Java type system to ensure program safety at compile-time - PowerPoint PPT Presentation


<p>Kannotator: Inferring Type Information from Java Bytecode</p> <p>KAnnotator: Inferring Type Information from Java Byte CodesAlexey SedunovAndrey BreslavSvetlana IsakovaEvgeny GerashchenkoJetBrains, s. r. o.2013</p> <p>Annotation InferenceSeveral languages on the Java platform refine Java type system to ensure program safety at compile-timeKotlin: nullable/non-nullable typesIn practice interoperability with existing Java code requires developers to provide missing type information, e.g. in a form of annotations.KAnnotator is a tool which automatically infers type annotations for a given set of classes (libraries) based on their bytecode2KAnnotator FeaturesAnnotation inference based on the bytecode of library classes@Nullable/@NotNull@MutableSupport of predefined annotationsInternal vs. external annotationsVerification modeExtensible context-insensitive inference engineOpen-sourcehttps://github.com/jetbrains/kannotator 3ComparisonJuliahttp://julia.scienze.univr.it/general frameworkmore preciselonger runtimeJQualhttp://www.cs.umd.edu/projects/PL/jqual/general frameworkmore precise mutabilityAST-driven NIThttp://nit.gforge.inria.fr/sound theorymore precise treatment of fieldsspecializedlonger runtime</p> <p>4Inference Process Overview5Load predefined annotationsPropagate annotationsApply inference to dependency graphConstruct dependency &amp; inheritance graphsLoad class filesProcess conflictsBytecode Inference EngineInference engine is based on the ObjectWeb 2 ASM data-flow analysis frameworkCompatible with ASM bytecode representationDoes not require explicit construction of CFGAnalyzer iterates over execution paths until all frames are stabilizedImprovements to the ASM analyzer:Pseudo-errors corresponding to possible abnormal terminationsDetection of unreachable pathsAnalysis-specific frame transformers</p> <p>6Mutability: Motivation7</p> <p>Mutability: Mutating Invocations void copy(@ReadOnly Collection from, @Mutable Collection to) { for (T fromElement : from) { //mutating invocation to.add(fromElement); }}8Mutability: Propagating Invocations void removeFirst(@Mutable Iterable a) { //mutability propagating invocation Iterator it = a.iterator(); if (it.hasNext()) { it.remove(); }}9Nullability: Motivationfun sort( a: Collection?):List?10 List sort(Collection a) { List list = new ArrayList(a); Collections.sort(list); return list;}JAVAKOTLINfun sort( a: Collection):ListNo type informationNullability: Annotation Criteria11@NullableNull does not reach ANY error nodeNull or Not Null reach SOME return node@NotNullNull does not reach ANY return nodeNull reaches SOME error nodeNo Null is lostUNKNOWNNullability: @Nullablevoid foo1(@Nullable String s) {if (s == null) return; bar(s); // null reaches return}12void foo2(@Nullable String s) { if (s == null) s = "empty"; bar(s); // not-null reaches return}Nullability: @NotNullvoid foo3(@NotNull String s) { if (s == null) { throw new RuntimeException(); } bar(s);}13void foo4(@NotNull String s) { if (s.isEmpty()) return; bar(s);}</p> <p>Nullability: Unknownvoid foo5(String s) { if (check(s)) { throw new RuntimeException(); } if (s == null) { s = "empty"; } bar(s);}14StatisticsSize(MB)Number of methodsTime(Preprocess/Analyze)</p> <p>@NotNull/@Mutable(%)OW2 ASM 4.00.31660</p>


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