Berkeley UPC - Unified Parallel C



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NEW Dec 10, 2021 -- Berkeley UPC version 2021.12.0 released!

The UPC Language

 Unified Parallel C (UPC) is an extension of the C programming language designed for high performance computing on large-scale parallel machines.The language provides a uniform programming model for both shared and distributed memory hardware. The programmer is presented with a single shared, partitioned address space, where variables may be directly read and written by any processor, but each variable is physically associated with a single processor. UPC uses a Single Program Multiple Data (SPMD) model of computation in which the amount of parallelism is fixed at program startup time, typically with a single thread of execution per processor.

In order to express parallelism, UPC extends ISO C 99 with the following constructs:

The UPC language evolved from experiences with three other earlier languages that proposed parallel extensions to ISO C 99: AC , Split-C, and Parallel C Preprocessor (PCP). UPC is not a superset of these three languages, but rather an attempt to distill the best characteristics of each. UPC combines the programmability advantages of the shared memory programming paradigm and the control over data layout and performance of the message passing programming paradigm.


Our work in the LBNL Pagoda Group

Berkeley UPC downloads since 01/May/2005
Berkeley UPC Runtime Source 176193
Berkeley UPC Translator Source 36451
Berkeley UPC Cygwin Binary 3381
Berkeley UPC MacOS Binary 10093
Combined Total 226118

The Berkeley UPC compiler suite is currently maintained primarily by the Pagoda Project in the CLaSS Group at Lawrence Berkeley National Laboratory. The goal of the Berkeley UPC team is to develop a portable, high performance implementation of UPC for large-scale multiprocessors, PC clusters, and clusters of shared memory multiprocessors.  We are developing an open-source UPC compiler suite whose goals are portability and high-performance.

The major components of our project are:

Some of the research findings from these areas of work can be found on our publications page.

UPC Compiler Infrastructure

There are multiple compiler infrastructures available for use with the Berkeley UPC runtime and compiler driver. The LLVM-based (Clang-UPC) and GCC-based (GUPC) compilers are developed by INTREPID Technology Inc.. An Open64-based (BUPC) translator is developed at LBNL. Currently multiple options encompassing these technologies are supported, for details please see the download page.

All compilers have been tested using the same procedure and our recommendations in terms of robustness and performance are below.

  1. Clang-UPC source-to-source UPC-to-C (CUPC2C) translator
    We consider this to be the most robust option.
    Though results will vary with your choice of a backend C compiler, this option is likely to result in best performance.
  2. Clang-UPC source-to-binary (CUPC) compiler
    We believe this to be as robust as CUPC2C.
    The performance is determined by LLVM (no option to use other backend compilers).
  3. Open64-based source-to-source UPC-to-C (BUPC) translator
    This is the default compiler, hosted as a netcompile service by LBNL.
    Performance is determined by the backend C compiler.
  4. GNU UPC source-to-binary (GUPC) compiler
    We consider this option to be generally robust.
    The performance is determined by GCC (no option to use other backend compilers)

All of the compiler options above use the Berkeley UPC runtime and compiler driver, which is available on the download page.

Related Links

Principal Investigator:
Katherine Yelick

General contact info

Berkeley UPC is developed and maintained by the Pagoda Project at Lawrence Berkeley National Laboratory,
and is funded by the DOE Office of Science and the Department of Defense.
Prior work has included contributions from UC Berkeley students and faculty, under various funding agencies.


This page last modified on Thursday, 23-Dec-2021 14:05:26 PST