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About

I'm a post-doctoral researcher at the SPeCS lab in the Faculty of Engineering, University of Porto. My area of expertise is source-to-source compilers and code generation, and I have done work both in high-level languages, such as MATLAB and C++, and low-level languages, such as assembly and VHDL.

From 2012 to 2015, my main line of research was MATLAB to C compilation, and I was the creator and main developer of the tool MATISSE (specs.fe.up.pt/tools/matisse). Currently I am working on Clava (specs.fe.up.pt/tools/clava), a C++ source-to-source transformation tool based on Clang, as part of the H2020 project ANTAREX (antarex-project.eu) which focus on strategies for autotunning and energy efficiency in HPC.

Previous work includes translation of Perl-Compatible Regular Expressions (PCRE) to HDL, and automatic runtime migration of loops found in MicroBlaze assembly traces to customized hardware (the subject of the PhD thesis).

I've received a Bachelor's degree in Computer Systems and Informatics from the Univ. of Algarve in July 2006, and in July 2012 received the Ph.D. degree from Instituto Superior Técnico (IST), Lisbon, with the thesis “Mapping Runtime-Detected Loops from Microprocessors to Reconfigurable Processing Units”.

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Publications

2019

Supporting the Scale-up of High Performance Application to Pre-Exascale Systems: The ANTAREX Approach

Authors
Silvano, C; Agosta, G; Bartolini, A; Beccari, AR; Benini, L; Besnard, L; Bispo, J; Cmar, R; Cardoso, JMP; Cavazzoni, C; Cesarini, D; Cherubin, S; Ficarelli, F; Gadioli, D; Golasowski, M; Lasri, I; Libri, A; Manelfi, C; Martinovic, J; Palermo, G; Pinto, P; Rohou, E; Sanna, N; Slaninova, K; Vitali, E;

Publication
2019 27TH EUROMICRO INTERNATIONAL CONFERENCE ON PARALLEL, DISTRIBUTED AND NETWORK-BASED PROCESSING (PDP)

Abstract
The ANTAREX project developed an approach to the performance tuning of High Performance applications based on an Aspect-oriented Domain Specific Language (DSL), with the goal to simplify the enforcement of extra-functional properties in large scale applications. The project aims at demonstrating its tools and techniques on two relevant use cases, one in the domain of computational drug discovery, the other in the domain of online vehicle navigation. In this paper, we present an overview of the project and of its main achievements, as well as of the large scale experiments that have been planned to validate the approach.

2019

Nonio — modular automatic compiler phase selection and ordering specialization framework for modern compilers

Authors
Nobre, R; Bispo, J; Carvalho, T; Cardoso, JMP;

Publication
SoftwareX

Abstract
This article presents Nonio, a modular, easy-to-use, design space exploration framework focused on exploring custom combinations of compiler flags and compiler sequences. We describe the framework and discuss its use with two of the most popular compiler toolchains, GCC and Clang+LLVM. Particularly, we discuss implementation details in the context of flag selection, when using GCC, and phase selection and ordering, when using Clang+LLVM. The framework software organization allows to easily add new components as plug-ins (e.g., an exploration algorithm, an objective metric, integration with another compiler toolchain). The software architecture provides well-defined interfaces, in order to enable seamless composition and interaction between different components. We present, as an example, a use case where we rely on Nonio to obtain custom compiler flags for reducing the execution time and the energy consumption of a C program, in relation to the best predetermined optimization settings provided by the compiler (e.g., –O3). © 2019

2019

The ANTAREX domain specific language for high performance computing

Authors
Silvano, C; Agosta, G; Bartolini, A; Beccari, AR; Benini, L; Besnard, L; Bispo, J; Cmar, R; Cardoso, JMP; Cavazzoni, C; Cesarini, D; Cherubin, S; Ficarelli, F; Gadioli, D; Golasowski, M; Libri, A; Martinovic, J; Palermo, G; Pinto, P; Rohou, E; Slaninova, K; Vitali, E;

Publication
MICROPROCESSORS AND MICROSYSTEMS

Abstract
The ANTAREX project relies on a Domain Specific Language (DSL) based on Aspect Oriented Programming (AOP) concepts to allow applications to enforce extra functional properties such as energy-efficiency and performance and to optimize Quality of Service (QoS) in an adaptive way. The DSL approach allows the definition of energy-efficiency, performance, and adaptivity strategies as well as their enforcement at runtime through application autotuning and resource and power management. In this paper, we present an overview of the key outcome of the project, the ANTAREX DSL, and some of its capabilities through a number of examples, including how the DSL is applied in the context of the project use cases.

2018

Aspect composition for multiple target languages using LARA

Authors
Pinto, P; Carvalho, T; Bispo, J; Ramalho, MA; Cardoso, JMP;

Publication
Computer Languages, Systems and Structures

Abstract
Usually, Aspect-Oriented Programming (AOP) languages are an extension of a specific target programming language (e.g., AspectJ for JAVA and AspectC++ for C++). Although providing AOP support with target language extensions may ease the adoption of an approach, it may impose constraints related with constructs and semantics. Furthermore, by tightly coupling the AOP language to the target language the reuse potential of many aspects, especially the ones regarding non-functional requirements, is lost. LARA is a domain-specific language inspired by AOP concepts, having the specification of source-to-source transformations as one of its main goals. LARA has been designed to be, as much as possible, independent of the target language and to provide constructs and semantics that ease the definition of concerns, especially related to non-functional requirements. In this paper, we propose techniques to overcome some of the challenges presented by a multilanguage approach to AOP of cross-cutting concerns focused on non-functional requirements and applied through the use of a weaving process. The techniques mainly focus on providing well-defined library interfaces that can have concrete implementations for each supported target language. The developer uses an agnostic interface and the weaver provides a specific implementation for the target language. We evaluate our approach using 8 concerns with varying levels of language agnosticism that support 4 target languages (C, C++, JAVA and MATLAB) and show that the proposed techniques contribute to more concise LARA aspects, high reuse of aspects, and to significant effort reductions when developing weavers for new imperative, object-oriented programming languages. © 2018 Elsevier Ltd

2018

Aspect-Driven Mixed-Precision Tuning Targeting GPUs

Authors
Nobre, R; Reis, L; Bispo, J; Carvalho, T; Cardoso, JMP; Cherubin, S; Agosta, G;

Publication
Proceedings of the 9th Workshop on Parallel Programming and RunTime Management Techniques for Manycore Architectures and 7th Workshop on Design Tools and Architectures for Multicore Embedded Computing Platforms, PARMA-DITAM@HiPEAC 2018, Manchester, United Kingdom, January 23-23, 2018

Abstract
Writing mixed-precision kernels allows to achieve higher throughput together with outputs whose precision remain within given limits. The recent introduction of native half-precision arithmetic capabilities in several GPUs, such as NVIDIA P100 and AMD Vega 10, contributes to make precision-tuning even more relevant as of late. However, it is not trivial to manually find which variables are to be represented as half-precision instead of single- or double-precision. Although the use of half-precision arithmetic can speed up kernel execution considerably, it can also result in providing non-usable kernel outputs, whenever the wrong variables are declared using the half-precision data-type. In this paper we present an automatic approach for precision tuning. Given an OpenCL kernel with a set of inputs declared by a user (i.e., the person responsible for programming and/or tuning the kernel), our approach is capable of deriving the mixed-precision versions of the kernel that are better improve upon the original with respect to a given metric (e.g., time-to-solution, energy-to-solution). We allow the user to declare and/or select a metric to measure and to filter solutions based on the quality of the output. We implement a proof-of-concept of our approach using an aspect-oriented programming language called LARA. It is capable of generating mixed-precision kernels that result in considerably higher performance when compared with the original single-precision floating-point versions, while generating outputs that can be acceptable in some scenarios. © 2018 Copyright held by the owner/author(s).