Proceedings of the ACM on Programming Languages最新文献

{"title":"Structural Subtyping as Parametric Polymorphism","authors":"Tang, Wenhao, Hillerström, Daniel, McKinna, James, Steuwer, Michel, Dardha, Ornela, Fu, Rongxiao, Lindley, Sam","doi":"10.1145/3622836","DOIUrl":"https://doi.org/10.1145/3622836","url":null,"abstract":"Structural subtyping and parametric polymorphism provide similar flexibility and reusability to programmers. For example, both features enable the programmer to provide a wider record as an argument to a function that expects a narrower one. However, the means by which they do so differs substantially, and the precise details of the relationship between them exists, at best, as folklore in literature. In this paper, we systematically study the relative expressive power of structural subtyping and parametric polymorphism. We focus our investigation on establishing the extent to which parametric polymorphism, in the form of row and presence polymorphism, can encode structural subtyping for variant and record types. We base our study on various Church-style $lambda$-calculi extended with records and variants, different forms of structural subtyping, and row and presence polymorphism. We characterise expressiveness by exhibiting compositional translations between calculi. For each translation we prove a type preservation and operational correspondence result. We also prove a number of non-existence results. By imposing restrictions on both source and target types, we reveal further subtleties in the expressiveness landscape, the restrictions enabling otherwise impossible translations to be defined. More specifically, we prove that full subtyping cannot be encoded via polymorphism, but we show that several restricted forms of subtyping can be encoded via particular forms of polymorphism.","PeriodicalId":20697,"journal":{"name":"Proceedings of the ACM on Programming Languages","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136077527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Concrete Type Inference for Code Optimization using Machine Learning with SMT Solving","authors":"Fangke Ye, Jisheng Zhao, Jun Shirako, Vivek Sarkar","doi":"10.1145/3622825","DOIUrl":"https://doi.org/10.1145/3622825","url":null,"abstract":"Despite the widespread popularity of dynamically typed languages such as Python, it is well known that they pose significant challenges to code optimization due to the lack of concrete type information. To overcome this limitation, many ahead-of-time optimizing compiler approaches for Python rely on programmers to provide optional type information as a prerequisite for extensive code optimization. Since few programmers provide this information, a large majority of Python applications are executed without the benefit of code optimization, thereby contributing collectively to a significant worldwide wastage of compute and energy resources. In this paper, we introduce a new approach to concrete type inference that is shown to be effective in enabling code optimization for dynamically typed languages, without requiring the programmer to provide any type information. We explore three kinds of type inference algorithms in our approach based on: 1) machine learning models including GPT-4, 2) constraint-based inference based on SMT solving, and 3) a combination of 1) and 2). Our approach then uses the output from type inference to generate multi-version code for a bounded number of concrete type options, while also including a catch-all untyped version for the case when no match is found. The typed versions are then amenable to code optimization. Experimental results show that the combined algorithm in 3) delivers far superior precision and performance than the separate algorithms for 1) and 2). The performance improvement due to type inference, in terms of geometric mean speedup across all benchmarks compared to standard Python, when using 3) is 26.4× with Numba as an AOT optimizing back-end and 62.2× with the Intrepydd optimizing compiler as a back-end. These vast performance improvements can have a significant impact on programmers’ productivity, while also reducing their applications’ use of compute and energy resources.","PeriodicalId":20697,"journal":{"name":"Proceedings of the ACM on Programming Languages","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136114713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adventure of a Lifetime: Extract Method Refactoring for Rust","authors":"Sewen Thy, Andreea Costea, Kiran Gopinathan, Ilya Sergey","doi":"10.1145/3622821","DOIUrl":"https://doi.org/10.1145/3622821","url":null,"abstract":"We present a design and implementation of the automated \"Extract Method\" refactoring for Rust programs. Even though Extract Method is one of the most well-studied and widely used in practice automated refactorings, featured in all major IDEs for all popular programming languages, implementing it soundly for Rust is surprisingly non-trivial due to the restrictions of the Rust's ownership and lifetime-based type system. In this work, we provide a systematic decomposition of the Extract Method refactoring for Rust programs into a series of program transformations, each concerned with satisfying a particular aspect of Rust type safety, eventually producing a well-typed Rust program. Our key discovery is the formulation of Extract Method as a composition of naive function hoisting and a series of automated program repair procedures that progressively make the resulting program \"more well-typed\" by relying on the corresponding repair oracles. Those oracles include a novel static intra-procedural ownership analysis that infers correct sharing annotations for the extracted function's parameters, and the lifetime checker of rustc, Rust's reference compiler. We implemented our approach in a tool called REM---an automated Extract Method refactoring built on top of IntelliJ IDEA plugin for Rust. Our extensive evaluation on a corpus of changes in five popular Rust projects shows that REM (a) can extract a larger class of feature-rich code fragments into semantically correct functions than other existing refactoring tools, (b) can reproduce method extractions performed manually by human developers in the past, and (c) is efficient enough to be used in interactive development.","PeriodicalId":20697,"journal":{"name":"Proceedings of the ACM on Programming Languages","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136115398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gradual Typing for Effect Handlers","authors":"Max S. New, Eric Giovannini, Daniel R. Licata","doi":"10.1145/3622860","DOIUrl":"https://doi.org/10.1145/3622860","url":null,"abstract":"We present a gradually typed language, GrEff, with effects and handlers that supports migration from unchecked to checked effect typing. This serves as a simple model of the integration of an effect typing discipline with an existing effectful typed language that does not track fine-grained effect information. Our language supports a simple module system to model the programming model of gradual migration from unchecked to checked effect typing in the style of Typed Racket. The surface language GrEff is given semantics by elaboration to a core language Core GrEff. We equip Core GrEff with an inequational theory for reasoning about the semantic error ordering and desired program equivalences for programming with effects and handlers. We derive an operational semantics for the language from the equations provable in the theory. We then show that the theory is sound by constructing an operational logical relations model to prove the graduality theorem. This extends prior work on embedding-projection pair models of gradual typing to handle effect typing and subtyping.","PeriodicalId":20697,"journal":{"name":"Proceedings of the ACM on Programming Languages","volume":"280 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136115990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Historia: Refuting Callback Reachability with Message-History Logics","authors":"Meier, Shawn, Mover, Sergio, Kaki, Gowtham, Chang, Bor-Yuh Evan","doi":"10.1145/3622865","DOIUrl":"https://doi.org/10.1145/3622865","url":null,"abstract":"This paper considers the callback reachability problem --- determining if a callback can be called by an event-driven framework in an unexpected state. Event-driven programming frameworks are pervasive for creating user-interactive applications (apps) on just about every modern platform. Control flow between callbacks is determined by the framework and largely opaque to the programmer. This opacity of the callback control flow not only causes difficulty for the programmer but is also difficult for those developing static analysis. Previous static analysis techniques address this opacity either by assuming an arbitrary framework implementation or attempting to eagerly specify all possible callback control flow, but this is either too coarse to prove properties requiring callback-ordering constraints or too burdensome and tricky to get right. Instead, we present a middle way where the callback control flow can be gradually refined in a targeted manner to prove assertions of interest. The key insight to get this middle way is by reasoning about the history of method invocations at the boundary between app and framework code --- enabling a decoupling of the specification of callback control flow from the analysis of app code. We call the sequence of such boundary-method invocations message histories and develop message-history logics to do this reasoning. In particular, we define the notion of an application-only transition system with boundary transitions, a message-history program logic for programs with such transitions, and a temporal specification logic for capturing callback control flow in a targeted and compositional manner. Then to utilize the logics in a goal-directed verifier, we define a way to combine after-the-fact an assertion about message histories with a specification of callback control flow. We implemented a prototype message history-based verifier called Historia and provide evidence that our approach is uniquely capable of distinguishing between buggy and fixed versions on challenging examples drawn from real-world issues and that our targeted specification approach enables proving the absence of multi-callback bug patterns in real-world open-source Android apps.","PeriodicalId":20697,"journal":{"name":"Proceedings of the ACM on Programming Languages","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136077382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formally Verifying Optimizations with Block Simulations","authors":"Léo Gourdin, Benjamin Bonneau, Sylvain Boulmé, David Monniaux, Alexandre Bérard","doi":"10.1145/3622799","DOIUrl":"https://doi.org/10.1145/3622799","url":null,"abstract":"CompCert (ACM Software System Award 2021) is the first industrial-strength compiler with a mechanically checked proof of correctness. Yet, CompCert remains a moderately optimizing C compiler. Indeed, some optimizations of “gcc ‍-O1” such as Lazy Code Motion (LCM) or Strength Reduction (SR) were still missing: developing these efficient optimizations together with their formal proofs remained a challenge. Cyril Six et al. have developed efficient formally verified translation validators for certifying the results of superblock schedulers and peephole optimizations. We revisit and generalize their approach into a framework (integrated into CompCert) able to validate many more optimizations: an enhanced superblock scheduler, but also Dead Code Elimination (DCE), Constant Propagation (CP), and more noticeably, LCM and SR. In contrast to other approaches to translation validation, we co-design our untrusted optimizations and their validators. Our optimizations provide hints, in the forms of invariants or CFG morphisms , that help keep the formally verified validators both simple and efficient. Such designs seem applicable beyond CompCert.","PeriodicalId":20697,"journal":{"name":"Proceedings of the ACM on Programming Languages","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136077529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rhombus: A New Spin on Macros without All the Parentheses","authors":"Matthew Flatt, Taylor Allred, Nia Angle, Stephen De Gabrielle, Robert Bruce Findler, Jack Firth, Kiran Gopinathan, Ben Greenman, Siddhartha Kasivajhula, Alex Knauth, Jay McCarthy, Sam Phillips, Sorawee Porncharoenwase, Jens Axel Søgaard, Sam Tobin-Hochstadt","doi":"10.1145/3622818","DOIUrl":"https://doi.org/10.1145/3622818","url":null,"abstract":"Rhombus is a new language that is built on Racket. It offers the same kind of language extensibility as Racket itself, but using traditional (infix) notation. Although Rhombus is far from the first language to support Lisp-style macros without Lisp-style parentheses, Rhombus offers a novel synthesis of macro technology that is practical and expressive. A key element is the use of multiple binding spaces for context-specific sublanguages. For example, expressions and pattern-matching forms can use the same operators with different meanings and without creating conflicts. Context-sensitive bindings, in turn, facilitate a language design that reduces the notational distance between the core language and macro facilities. For example, repetitions can be defined and used in binding and expression contexts generally, which enables a smoother transition from programming to metaprogramming. Finally, since handling static information (such as types) is also a necessary part of growing macros beyond Lisp, Rhombus includes support in its expansion protocol for communicating static information among bindings and expressions. The Rhombus implementation demonstrates that all of these pieces can work together in a coherent and user-friendly language.","PeriodicalId":20697,"journal":{"name":"Proceedings of the ACM on Programming Languages","volume":"227 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136112526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying and Mitigating Cache Side Channel Leakage with Differential Set","authors":"Cong Ma, Dinghao Wu, Gang Tan, Mahmut Taylan Kandemir, Danfeng Zhang","doi":"10.1145/3622850","DOIUrl":"https://doi.org/10.1145/3622850","url":null,"abstract":"Cache side-channel attacks leverage secret-dependent footprints in CPU cache to steal confidential information, such as encryption keys. Due to the lack of a proper abstraction for reasoning about cache side channels, existing static program analysis tools that can quantify or mitigate cache side channels are built on very different kinds of abstractions. As a consequence, it is hard to bridge advances in quantification and mitigation research. Moreover, existing abstractions lead to imprecise results. In this paper, we present a novel abstraction, called differential set, for analyzing cache side channels at compile time. A distinguishing feature of differential sets is that it allows compositional and precise reasoning about cache side channels. Moreover, it is the first abstraction that carries sufficient information for both side channel quantification and mitigation. Based on this new abstraction, we develop a static analysis tool DSA that automatically quantifies and mitigates cache side channel leakage at the same time. Experimental evaluation on a set of commonly used benchmarks shows that DSA can produce more precise leakage bound as well as mitigated code with fewer memory footprints, when compared with state-of-the-art tools that only quantify or mitigate cache side channel leakage.","PeriodicalId":20697,"journal":{"name":"Proceedings of the ACM on Programming Languages","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136112529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hardware-Aware Static Optimization of Hyperdimensional Computations","authors":"Pu (Luke) Yi, Sara Achour","doi":"10.1145/3622797","DOIUrl":"https://doi.org/10.1145/3622797","url":null,"abstract":"Binary spatter code (BSC)-based hyperdimensional computing (HDC) is a highly error-resilient approximate computational paradigm suited for error-prone, emerging hardware platforms. In BSC HDC, the basic datatype is a hypervector , a typically large binary vector, where the size of the hypervector has a significant impact on the fidelity and resource usage of the computation. Typically, the hypervector size is dynamically tuned to deliver the desired accuracy; this process is time-consuming and often produces hypervector sizes that lack accuracy guarantees and produce poor results when reused for very similar workloads. We present Heim, a hardware-aware static analysis and optimization framework for BSC HD computations. Heim analytically derives the minimum hypervector size that minimizes resource usage and meets the target accuracy requirement. Heim guarantees the optimized computation converges to the user-provided accuracy target on expectation, even in the presence of hardware error. Heim deploys a novel static analysis procedure that unifies theoretical results from the neuroscience community to systematically optimize HD computations. We evaluate Heim against dynamic tuning-based optimization on 25 benchmark data structures. Given a 99% accuracy requirement, Heim-optimized computations achieve a 99.2%-100.0% median accuracy, up to 49.5% higher than dynamic tuning-based optimization, while achieving 1.15x-7.14x reductions in hypervector size compared to HD computations that achieve comparable query accuracy and finding parametrizations 30.0x-100167.4x faster than dynamic tuning-based approaches. We also use Heim to systematically evaluate the performance benefits of using analog CAMs and multiple-bit-per-cell ReRAM over conventional hardware, while maintaining iso-accuracy – for both emerging technologies, we find usages where the emerging hardware imparts significant benefits.","PeriodicalId":20697,"journal":{"name":"Proceedings of the ACM on Programming Languages","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136112661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Leaf: Modularity for Temporary Sharing in Separation Logic","authors":"Travis Hance, Jon Howell, Oded Padon, Bryan Parno","doi":"10.1145/3622798","DOIUrl":"https://doi.org/10.1145/3622798","url":null,"abstract":"In concurrent verification, separation logic provides a strong story for handling both resources that are owned exclusively and resources that are shared persistently (i.e., forever). However, the situation is more complicated for temporarily shared state, where state might be shared and then later reclaimed as exclusive. We believe that a framework for temporarily-shared state should meet two key goals not adequately met by existing techniques. One, it should allow and encourage users to verify new sharing strategies. Two, it should provide an abstraction where users manipulate shared state in a way agnostic to the means with which it is shared. We present Leaf, a library in the Iris separation logic which accomplishes both of these goals by introducing a novel operator, which we call guarding, that allows one proposition to represent a shared version of another. We demonstrate that Leaf meets these two goals through a modular case study: we verify a reader-writer lock that supports shared state, and a hash table built on top of it that uses shared state.","PeriodicalId":20697,"journal":{"name":"Proceedings of the ACM on Programming Languages","volume":"227 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136112808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}