Short-Circuit Dispatch: Accelerating Virtual Machine Interpreters on Embedded Processors

Kim, Channoh; Kim, Sung-Min; Cho, Hyeon Gyu; Kim, Dooyoung; Kim, Jaehyeok; Oh, Young Hoon; Jang, Hakbeom; Lee, Jae Woo

doi:10.1109/isca.2016.34

Cited by 5 publications

(4 citation statements)

References 19 publications

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“…It is possible to further duplicate [55] handlers to get more BTB entries [23]. Recent work has also proposed new hardware support for indirect speculation [69] [63] or to directly address BTB entries [41]. Many JVMs mutate bytecode in-place [22] to replace symbolic references with indexes and offsets.…”

Section: Optimizing Fixed Format Interpretersmentioning

confidence: 99%

A fast in-place interpreter for WebAssembly

Titzer¹

2022

Preprint

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WebAssembly (Wasm) is a compact, well-specified bytecode format that offers a portable compilation target with near-native execution speed. The bytecode format was specifically designed to be fast to parse, validate, and compile, positioning itself as a portable alternative to native code. It was pointedly not designed to be interpreted directly. Instead, design considerations at the time focused on competing with native code, utilizing optimizing compilers as the primary execution tier. Yet, in JIT scenarios, compilation time and memory consumption critically impact application startup, leading many Wasm engines to later deploy baseline (single-pass) compilers. Though faster, baseline compilers still take time and waste code space for infrequently executed code. A typical interpreter being infeasible, some engines resort to compiling Wasm not to machine code, but to a more compact, but easy to interpret format. This still takes time and wastes memory. Instead, we introduce in this article a fast in-place interpreter for WebAssembly, where no rewrite and no separate format is necessary. Our evaluation shows that in-place interpretation of Wasm code is space-efficient and fast, achieving performance on-par with interpreting a custom-designed internal format. This fills a hole in the execution tier space for Wasm, allowing for even faster startup and lower memory footprint than previous engine configurations.CCS Concepts: • Software and its engineering → Interpreters.

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Section: Optimizing Fixed Format Interpretersmentioning

confidence: 99%

A fast in-place interpreter for WebAssembly

Titzer¹

2022

Preprint

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“…Capability-based systems [21,32,48,102] provide object-based memory protection and isolation. Typed architectures [2,16,43,44,88] accelerate dynamic type checks. Whereas this prior work focuses on core design and uses a standard cache hierarchy, we focus on redesigning the memory hierarchy.…”

Section: Background On Memory-safe Languagesmentioning

confidence: 99%

Rethinking the Memory Hierarchy for Modern Languages

Tsai

Gan

Sánchez

2018

2018 51st Annual IEEE/ACM International Symposium on Microarchitecture (MICRO)

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We present Hotpads, a new memory hierarchy designed from the ground up for modern, memory-safe languages like Java, Go, and Rust. Memory-safe languages hide the memory layout from the programmer. This prevents memory corruption bugs and enables automatic memory management. Hotpads extends the same insight to the memory hierarchy: it hides the memory layout from software and takes control over it, dispensing with the conventional flat address space abstraction. This avoids the need for associative caches. Instead, Hotpads moves objects across a hierarchy of directly addressed memories. It rewrites pointers to avoid most associative lookups, provides hardware support for memory allocation, and unifies hierarchical garbage collection and data placement. As a result, Hotpads improves memory performance and efficiency substantially, and unlocks many new optimizations.

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“…To overcome this limitation, we could extend ShortCut to index the BTB with bytecode addresses instead of PCs. A similar approach is used in previous BTB proposals [22,25].…”

Section: Applicability To Interpretersmentioning

confidence: 99%

“…The second proposal by Kim et al [25] reduces the overheads of bytecode dispatching in interpreters by overlaying the bytecode jump table on the BTB. This scheme, however, is not flexible enough to support ICs.…”

Section: Related Workmentioning

confidence: 99%

ShortCut

Choi

Shull

Garzarán

et al. 2017

SIGARCH Comput. Archit. News

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The same flexibility that makes dynamic scripting languages appealing to programmers is also the primary cause of their low performance. To access objects of potentially different types, the compiler creates a dispatcher with a series of if statements, each performing a comparison to a type and a jump to a handler. This induces major overhead in instructions executed and branches mispredicted.This paper proposes architectural support to significantly improve the efficiency of accesses to objects. The idea is to modify the instruction that calls the dispatcher so that, under most conditions, it skips most of the branches and instructions needed to reach the correct handler, and sometimes even the execution of the handler itself. Our novel architecture, called ShortCut, performs two levels of optimization. Its Plain design transforms the call to the dispatcher into a call to the correct handler -bypassing the whole dispatcher execution. Its Aggressive design transforms the call to the dispatcher into a simple load or store -bypassing the execution of both dispatcher and handler. We implement the ShortCut software in the state-of-the-art Google V8 JIT compiler, and the ShortCut hardware in a simulator. We evaluate ShortCut with the Octane and SunSpider JavaScript application suites. Plain ShortCut reduces the average execution time of the applications by 30% running under the baseline compiler, and by 11% running under the maximum level of compiler optimization. Aggressive ShortCut performs only slightly better.

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Short-Circuit Dispatch: Accelerating Virtual Machine Interpreters on Embedded Processors

Cited by 5 publications

References 19 publications

A fast in-place interpreter for WebAssembly

A fast in-place interpreter for WebAssembly

Rethinking the Memory Hierarchy for Modern Languages

ShortCut

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