Survey on Instruction Selection: An Extensive and Modern Literature Review

Instruction selection is one of three optimisation problems involved in the code generator backend of a compiler. The instruction selector is responsible of transforming an input program from its target-independent representation into a target-specific form by making best use of the available machine instructions. Hence instruction selection is a crucial part of efficient code generation. Despite on-going research since the late 1960s, the last, comprehensive survey on the field was written more than 30 years ago. As new approaches and techniques have appeared since its publication, this brings forth a need for a new, up-to-date review of the current body of literature. This report addresses that need by performing an extensive review and categorisation of existing research. The report therefore supersedes and extends the previous surveys, and also attempts to identify where future research should be directed.Comment: Major changes: - Merged simulation chapter with macro expansion chapter - Addressed misunderstandings of several approaches - Completely rewrote many parts of the chapters; strengthened the discussion of many approaches - Revised the drawing of all trees and graphs to put the root at the top instead of at the bottom - Added appendix for listing the approaches in a table See doc for more inf

t|ket> : A retargetable compiler for NISQ devices

We present t|ket>, a quantum software development platform produced by Cambridge Quantum Computing Ltd. The heart of t|ket> is a language-agnostic optimising compiler designed to generate code for a variety of NISQ devices, which has several features designed to minimise the influence of device error. The compiler has been extensively benchmarked and outperforms most competitors in terms of circuit optimisation and qubit routing

Tecnologia adaptativa aplicada à otimização de código em compiladores

The programming memory space of embedded microcontrolled systems is usually limited. Although, compilers nowadays apply optimizing transformations to the embedded software, the lack of memory space can become a critical problem to the designer with the introduction of new features and corrections in the original software. In contrast, workstations hosting development systems for embedded applications are faster and have much more memory. Given this scenario, we have developed a peephole optimizer exploring an adaptive technique that requires more memory and execution time, but is capable to achieve a better compression ratio of the object code than a conventional peephole optimizer. The introduction of an adaptive action enables the algorithm to self-modify its behavior in response to a specific input condition and to search the sequence of optimization rules that best optimizes the object code among the many possible sequences resulted from the superposition of two or more equally applicable optimization rules.O espaço de memória de programação de sistemas microcontrolados embutidos é normalmente limitado. Embora os compiladores atuais apliquem transformações otimizantes ao software embutido, a falta de espaço de memória pode se tornar um problema crítico para o projetista com a introdução de novas facilidades e correções no software original. Por outro lado, as estações de trabalho hospedando os sistemas de desenvolvimento para aplicações embutidas são mais rápidas e dispõem de mais memória. Diante deste panorama, desenvolvemos um otimizador peephole explorando uma técnica adaptativa que requer mais memória e tempo de execução, mas é capaz de obter uma melhor taxa de compressão do código objeto do que um otimizador peephole convencional. A introdução de uma ação adaptativa permite que o algoritmo auto modifique o seu comportamento em resposta a uma condição de entrada específica e procure a seqüência de regras de otimização que melhor otimiza o código objeto entre as muitas seqüências possíveis resultantes da superposição de duas ou mais regras de otimização igualmente aplicáveis.Eje: Teoría (TEOR)Red de Universidades con Carreras en Informática (RedUNCI

Tecnologia adaptativa aplicada à otimização de código em compiladores

The programming memory space of embedded microcontrolled systems is usually limited. Although, compilers nowadays apply optimizing transformations to the embedded software, the lack of memory space can become a critical problem to the designer with the introduction of new features and corrections in the original software. In contrast, workstations hosting development systems for embedded applications are faster and have much more memory. Given this scenario, we have developed a peephole optimizer exploring an adaptive technique that requires more memory and execution time, but is capable to achieve a better compression ratio of the object code than a conventional peephole optimizer. The introduction of an adaptive action enables the algorithm to self-modify its behavior in response to a specific input condition and to search the sequence of optimization rules that best optimizes the object code among the many possible sequences resulted from the superposition of two or more equally applicable optimization rules.O espaço de memória de programação de sistemas microcontrolados embutidos é normalmente limitado. Embora os compiladores atuais apliquem transformações otimizantes ao software embutido, a falta de espaço de memória pode se tornar um problema crítico para o projetista com a introdução de novas facilidades e correções no software original. Por outro lado, as estações de trabalho hospedando os sistemas de desenvolvimento para aplicações embutidas são mais rápidas e dispõem de mais memória. Diante deste panorama, desenvolvemos um otimizador peephole explorando uma técnica adaptativa que requer mais memória e tempo de execução, mas é capaz de obter uma melhor taxa de compressão do código objeto do que um otimizador peephole convencional. A introdução de uma ação adaptativa permite que o algoritmo auto modifique o seu comportamento em resposta a uma condição de entrada específica e procure a seqüência de regras de otimização que melhor otimiza o código objeto entre as muitas seqüências possíveis resultantes da superposição de duas ou mais regras de otimização igualmente aplicáveis.Eje: Teoría (TEOR)Red de Universidades con Carreras en Informática (RedUNCI

Generated Peephole Optimizations in LLVM Compiler

Jednou z důležitých vlastností aplikačně specifických procesorů je jejich výkon. Aby byl co největší, musí se překladač přizpůsobit potřebám procesoru, pre který bude překládat a generovat co nejefektívnejší kód. Jedním ze způsobů přizpůsobení se je hledání vhodných instrukcií, které je možné implementovat jako jednu instrukci s více výstupy. Následně se dá vygenerovaný kód zefektivnit pomocí peephole optimalizátoru, který vyhledává skupiny instrukcí, které může směnit za jejich efektivnejší varianty. Tato práce popisuje problém nacházení a výběru instrukcí s více výsledky. Taktéž poskytuje stručný přehled několika nejznámějších algoritmů na řešení tohoto problému. Na závěr skoumá uplatnění a začlenění řešení spolu s peephole optimalizacemi, do překladače LLVM.One of the important feature of application specific processors is performance. To maximize it, the compiler must adapt to needs of processor that it is going to compile for and it must generate the most efficient code. One of the ways to do that is to search for appropriate instructions that can be implemented as one instruction with multiple outputs. Afterwards the generated code can be parsed through peephole optimizations that search for instruction patterns and replace them with other instructions to make code more effective. This paper describes the problem of finding and selecting suitable candidates for multiple output instructions. It also provides a brief overview of the few best known algorithms that solve this problem. Eventually it examines possibilities of incorporating this optimizations to LLVM compiler.

Peephole Optimizer for Configurable Processor Architectures

Tato bakalářská práce se zabývá vytvořením peephole optimalizátoru pro překladač programovacího jazyka C. Práce se skládá ze studie optimalizační techniky zvané peephole optimalizace. Hlavní částí práce je návrh procesu peephole optimalizace. Výsledkem práce je funkční program peephole optimalizátoru.This bachelor's thesis deals with creation of peephole optimizer for the compiler of programming language C. This work consists of study of optimization technique called peephole optimization. Main part of this work is the design of peephole optimization process. As the result of this work functional program of peephole optimizer was created.

Is dynamic compilation possible for embedded systems ?

International audienceJIT compilation and dynamic compilation are powerful techniques allowing to delay the final code generation to the run-time. There is many benefits : improved portability, virtual machine security, etc. Unforturnately the tools used for JIT compilation and dynamic compilation does not met the classical requirement for embedded platforms: memory size is huge and code generation has big overheads. In this paper we show how dynamic code specialization (JIT) can be used and be beneficial in terms of execution speed and energy consumption with memory footprint kept under control. We based our approaches on our tool de-Goal and on LLVM, that we extended to be able to produce lightweight runtime specializers from annotated LLVM programs. Benchmarks are manipulated and transformed into templates and a specialization routine is build to instantiate the routines. Such approach allows to produce efficient special-izations routines, with a minimal energy consumption and memory footprint compare to a generic JIT application. Through some benchmarks, we present its efficiency in terms of speed, energy and memory footprint. We show that over static compilation we can achieve a speed-up of 21 % in terms of execution speed but also a 10 % energy reduction with a moderate memory footprint

Janus: Statically-Driven and Profile-Guided Automatic Dynamic Binary Parallelisation

We present Janus, a framework that addresses the challenge of automatic binary parallelisation. Janus uses same-ISA dynamic binary modification to optimise application binaries, controlled by static analysis with judicious use of software speculation and runtime checks that ensure the safety of the optimisations. A static binary analyser first examines a binary executable, to determine the loops that are amenable to parallelisation and the transformations required. These are encoded as a series of rewrite rules, the steps needed to convert a serial loop into parallel form. The Janus dynamic binary modifier reads both the original executable and rewrite rules and carries out the transformations on a per-basic-block level just-in-time before execution. Lifting static analysis out of the runtime enables the global and profile-guided views of the application; ambiguities from static binary analysis can in turn be addressed through a combination of dynamic runtime checks and speculation guard against data dependence violations. It allows us to parallelise even those loops containing dynamically discovered code. We demonstrate Janus by parallelising a range of optimised SPEC CPU 2006 benchmarks, achieving average speedups of 2.1× and 6.0× in the best case.Arm Ltd Engineering and Physical Sciences Research Council (EP/K026399/1), Engineering and Physical Sciences Research Council (EP/P020011/1