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This package includes both the tool pluto and libpluto. The 'pluto' tool is a source-to-source transfomer meant to be run via the polycc script. libpluto provides a thread-safe library interface.


Pluto and libpluto are available under the MIT LICENSE. Please see the file LICENSE in the top-level directory for more details.



A Linux distribution. Pluto has been tested on x86 and x86-64 machines running Fedora, Ubuntu, and RedHat Enterprise Server. Solaris should also be fine if you have GNU utilities.

  • In order to use the development version from Pluto's git repository, automatic build system tools including autoconf, automake, and libtool are needed.

  • LLVM/Clang (2.9 or higher) along with its development/header files is needed for the pet submodule. These packages are available in distribution repositories, or could be installed by building LLVM and Clang from sources. On a Fedora distribution, these could be typically installed with: $ dnf -y install llvm-devel clang-devel

  • LLVM FileCheck is used for Pluto's test suite. (On a Fedora, this is part of the 'llvm' package.)

  • GMP (GNU multi precision arithmetic library) is needed by ISL (one of the included libraries). If it's not already on your system, it can be installed easily with, for eg., 'sudo yum -y install gmp gmp-devel' on a Fedora ('sudo apt-get install libgmp3-dev' or something similar on an Ubuntu).

Pluto includes all polyhedral libraries that it depends on. See pet/README for pet's pre-requisites.


Stable release

$ tar zxvf pluto-0.11.4.tar.gz $ cd pluto-0.11.4/ $ ./configure $ make $ make test

configure can be provided --with-isl-prefix= to build with another isl, otherwise the bundled isl is used.

Development version from Git

$ git clone git:// $ cd pluto/ $ git submodule init $ git submodule update $ ./ $ ./configure [--enable-debug] [--with-isl-prefix=] $ make $ make test

  • --with-isl-prefix= to compile and link with an already installed isl. By default, the version of isl bundled with Pluto will be used.

'polycc' is the wrapper script around src/pluto (core transformer) and all other components. 'polycc' runs all of these in sequence on an input C program (with the section to parallelize/optimize marked) and is what a user should use on input. Output generated is OpenMP parallel C code that can be readily compiled and run on shared-memory parallel machines like general-purpose multicores. libpluto.{so,a} is also built and can be found in src/.libs/. 'make install' will install it.


  • Use '#pragma scop' and '#pragma endscop' around the section of code you want to parallelize/optimize.

  • Then, just run


    The transformation is also printed out, and test.par.c will have the parallelized code. If you want to see intermediate files, like the .cloog file generated (.opt.cloog, .tiled.cloog, or .par.cloog depending on command-line options provided), use --debug on command line.

  • Tile sizes can be specified in a file 'tile.sizes', otherwise default sizes will be set. See doc/DOC.txt on how to specify the sizes.

To run a good number of experiments on a code, it is best to use the setup created for example codes in the examples/ directory. If you do not have ICC (Intel C compiler), uncomment line 9 and comment line 8 of examples/ to use GCC.

  • Just copy one of the sample directories in examples/, edit Makefile (SRC = )

  • do a make (this will build all executables; 'orig' is the original code compiled with the native compiler, 'tiled' is the tiled code, 'par' is the OpenMP parallelized + locality optimized code. One could do 'make ' where target can be orig, orig_par, opt, tiled, par, pipepar, etc. (see examples/ for full list)

  • 'make test' to test for correctness, 'make perf' to compare performance



./polycc -h

or see documentation (doc/DOC.txt) for details


Lets say we are trying the 2-d gauss seidel kernel. In examples/seidel, do 'make par'; this will generate seidel.par.c from seidel.c and also compile it to generate 'par'. Likewise, 'make tiled' for 'tiled' and 'make orig' for 'orig'.

$ cd examples/seidel

seidel.c: This is the original code (the kernel in this code is extracted). 'orig' is the corresponding executable when compiled with the native compiler (gcc or icc for eg.) with optimization flags, 'orig_par' with the native compiler's auto-parallelization enabled.

seidel.opt.c: This is the transformed code without tiling (this is of not much use, except for seeing benefits of fusion in some cases). 'opt' is the corresponding executable.

seidel.tiled.c: This is Pluto generated code optimized for locality with tiling and other transformations, but not not parallelized - this should be used for sequential execution. 'tiled' is the corresponding executable.

seidel.par.c: This is Pluto parallelized code optimized for locality and parallelism with tiling and other transformations. This code has OpenMP pragmas. 'par' is the corresponding executable.

  • To change any of the flags used for an example, edit the top section of examples/ or the Makefile in the example directory

  • To manually specify tile sizes, create tile.sizes; see examples/matmul/ for example or doc/DOC.txt for more information on setting tile sizes.

The executables already have timers; you just have to run them and that will print execution time for the core part of the computation as well.

To run the Pluto parallelized version:

$ OMP_NUM_THREADS=4; ./par

To run native compiler optimized/auto-parallelized version:

$ OMP_NUM_THREADS=4; ./orig_par

To run the original unparallelized code:

$ ./orig

To run the locality optimized version generated by Pluto:

$ ./tiled

  • 'make clean' in the particular example's directory removes all executables as well as generated codes

To launch a complete verification that compares output of tiled, par with orig for all examples, in examples/, run 'make test'.

[examples/ ]$ make test


  • See doc/DOC.txt for an overview of the system and details on all command-line options.

  • For specifying custom tile sizes through 'tile.sizes' file, see doc/DOC.txt

  • For specifying custom fusion structure through '.fst' file, see doc/DOC.txt


Please report bugs and issues at For questions and general discussion, please email [email protected] after joining the group:

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