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Publicações

Publicações por João Bispo

2015

C and OpenCL Generation from MATLAB

Autores
Bispo, J; Reis, L; Cardoso, JMP;

Publicação
30TH ANNUAL ACM SYMPOSIUM ON APPLIED COMPUTING, VOLS I AND II

Abstract
In many engineering and science areas, models are developed and validated using high-level programing languages and environments as is the case with MATLAB. In order to target the multicore heterogeneous architectures being used on embedded systems to provide high performance computing with acceptable energy/power envelops, developers manually migrate critical code sections to lower-level languages such as C and OpenCL, a time consuming and error prone process. Thus, automatic source-to-source approaches are highly desirable. We present an approach to compile MATLAB and output equivalent C/OpenCL code to target architectures, such as GPU based hardware accelerators. We evaluate our approach on an existing MATLAB compiler framework named MATISSE. The OpenCL generation relies on the manual insertion of directives to guide the compilation and is also capable of generating C wrapper code to interface and synchronize with the OpenCL code. We evaluated the compiler with a number of benchmarks from different domains and the results are very encouraging.

2017

Compiler Techniques for Efficient MATLAB to OpenCL Code Generation

Autores
Reis, L; Bispo, J; Cardoso, JMP;

Publicação
Proceedings of the 5th International Workshop on OpenCL, IWOCL 2017, Toronto, Canada, May 16-18, 2017

Abstract
MATLAB is a high-level language used in various scientific and engineering fields. Deployment of well-Tested MATLAB code to production would be highly desirable, but in practice a number of obstacles prevent this, notably performance and portability. Although MATLAB-To-C compilers exist, the performance of the generated C code may not be sufficient and thus it is important to research alternatives, such as CPU parallelism, GPGPU computing and FPGAS. OpenCL is an API and programming language that allows targeting these devices, hence the motivation for MATLAB-To-OpenCL compilation. In this paper, we describe our recent efforts on offloading code to OpenCL devices in the context of our MATLAB to C/OpenCL compiler. © 2017 ACM.

2016

SSA-based MATLAB-to-C compilation and optimization

Autores
Reis, L; Bispo, J; Cardoso, JMP;

Publicação
Proceedings of the 3rd ACM SIGPLAN International Workshop on Libraries, Languages, and Compilers for Array Programming, ARRAY@PLDI 2016, Santa Barbara, CA, USA, June 14, 2016

Abstract
Many fields of engineering, science and finance use models that are developed and validated in high-level languages such as MATLAB. However, when moving to environments with resource constraints or portability challenges, these models often have to be rewritten in lower-level languages such as C. Doing so manually is costly and error-prone, but automated approaches tend to generate code that can be substantially less efficient than the handwritten equivalents. Additionally, it is usually difficult to read and improve code generated by these tools. In this paper, we describe how we improved our MATLAB-to-C compiler, based on the MATISSE framework, to be able to compete with handwritten C code. We describe our new IR and the most important optimizations that we use in order to obtain acceptable performance. We also analyze multiple C code versions to identify where the generated code is slower than the handwritten code and identify a few key improvements to generate code capable of outperforming handwritten C. We evaluate the new version of our compiler using a set of benchmarks, including the Disparity benchmark, from the San Diego Vision Benchmark Suite, on a desktop computer and on an embedded device. The achieved results clearly show the efficiency of the current version of the compiler. Copyright is held by the owner/author(s). Publication rights licensed to ACM.

2015

Transparent Acceleration of Program Execution Using Reconfigurable Hardware

Autores
Paulino, N; Ferreira, JC; Bispo, J; Cardoso, JMP;

Publicação
2015 DESIGN, AUTOMATION & TEST IN EUROPE CONFERENCE & EXHIBITION (DATE)

Abstract
The acceleration of applications, running on a general purpose processor (GPP), by mapping parts of their execution to reconfigurable hardware is an approach which does not involve program's source code and still ensures program portability over different target reconfigurable fabrics. However, the problem is very challenging, as suitable sequences of GPP instructions need to be translated/mapped to hardware, possibly at runtime. Thus, all mapping steps, from compiler analysis and optimizations to hardware generation, need to be both efficient and fast. This paper introduces some of the most representative approaches for binary acceleration using reconfigurable hardware, and presents our binary acceleration approach and the latest results. Our approach extends a GPP with a Reconfigurable Processing Unit (RPU), both sharing the data memory. Repeating sequences of GPP instructions are migrated to an RPU composed of functional units and interconnect resources, and able to exploit instruction-level parallelism, e.g., via loop pipelining. Although we envision a fully dynamic system, currently the RPU resources are selected and organized offline using execution trace information. We present implementation prototypes of the system on a Spartan-6 FPGA with a MicroBlaze as GPP and the very encouraging results achieved with a number of benchmarks.

2013

Transparent runtime migration of loop-based traces of processor instructions to reconfigurable processing units

Autores
Bispo, J; Paulino, N; Cardoso, JMP; Ferreira, JC;

Publicação
International Journal of Reconfigurable Computing

Abstract
The ability to map instructions running in a microprocessor to a reconfigurable processing unit (RPU), acting as a coprocessor, enables the runtime acceleration of applications and ensures code and possibly performance portability. In this work, we focus on the mapping of loop-based instruction traces (called Megablocks) to RPUs. The proposed approach considers offline partitioning and mapping stages without ignoring their future runtime applicability. We present a toolchain that automatically extracts specific trace-based loops, called Megablocks, from MicroBlaze instruction traces and generates an RPU for executing those loops. Our hardware infrastructure is able to move loop execution from the microprocessor to the RPU transparently, at runtime, and without changing the executable binaries. The toolchain and the system are fully operational. Three FPGA implementations of the system, differing in the hardware interfaces used, were tested and evaluated with a set of 15 application kernels. Speedups ranging from 1.26 × to 3.69 × were achieved for the best alternative using a MicroBlaze processor with local memory. © 2013 João Bispo et al.

2013

Transparent Trace-Based Binary Acceleration for Reconfigurable HW/SW Systems

Autores
Bispo, J; Paulino, N; Cardoso, JMP; Ferreira, JC;

Publicação
IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS

Abstract
This paper presents a novel approach to accelerate program execution by mapping repetitive traces of executed instructions, called Megablocks, to a runtime reconfigurable array of functional units. An offline tool suite extracts Megablocks from microprocessor instruction traces and generates a Reconfigurable Processing Unit (RPU) tailored for the execution of those Megablocks. The system is able to transparently movebcomputations from the microprocessor to the RPU at runtime. A prototype implementation of the system using a cacheless MicroBlaze microprocessor running code located in external memory reaches speedups from 2.2x to 18.2x for a set of 14 benchmark kernels. For a system setup which maximizes microprocessor performance by having the application code located in internal block RAMs, speedups from 1.4x to 2.8x were estimated.

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