René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Support for `invokedynamic` instruction in the engine","articleBody":"**Description**\r\n\r\nEngine currently does not support the `dynamicinvoke` bytecode instruction introduced in JDK 7.\r\n\r\nAn important case where `invokedynamic` is necessary is string concatenation: starting from Java 9, the operator `+` for `String` is implemented using `dynamicinvoke`. As a result, the plugin fails to generate tests for string concatenation when the code is compiled using JDK 9 or later (the primary concern is JDK 11).\r\n\r\nTo support `+` operator for `String` in Java 11, a fallback implementation has been provided that triggers concrete execution every time `invokedynamic` is encountered (PR . It is clearly a hack, and a proper implementation of `invokedynamic` is necessary.\r\n\r\nSoot sometimes replaces invokedynamic with other invoke* opcodes (e.g., for lambdas), but it is supposedly a special case. For example, the Jimple graph for string concatenation with `+` includes `JDynamicInvokeExpr` expression.\r\n\r\n**Expected behavior**\r\n\r\nThe implementation of `invokedynamic` instruction in the engine should update the global graph with the graph of the bootstrap method and generate branches corresponding to possible outcomes of `invokedynamic` along with type and/or value constraints to discard unnecessary paths.\r\n\r\n**Environment**\r\n\r\nThe `invokedynamic` instruction is present in JDK 7 or later.\r\n\r\nThe feature does not depend on any specific UnitTestBot configuration.\r\n\r\n**Potential alternatives**\r\n\r\nPossible approaches to support `dynamicinvoke` are under investigation.\r\n\r\n**Context**\r\n\r\n  * The paper that describes `invokedynamic` representation in Soot: [bodden12invokedynamic.pdf](https://www.bodden.de/pubs/bodden12invokedynamic.pdf)\r\n  * [JVM spec (JDK 7), chapter 6](https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-6.html)\r\n  * [Documentation](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/invoke/package-summary.html) for `java.lang.invoke` (JDK 11)","author":{"url":"https://github.com/dtim","@type":"Person","name":"dtim"},"datePublished":"2022-07-04T08:48:47.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/386/UTBotJava/issues/386"}