Difference between revisions of "Toolchain"

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(→‎The nu+ LLVM Structure)
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*  [[nu+ Libraries | ''nu+'' Libraries]]
 
*  [[nu+ Libraries | ''nu+'' Libraries]]
  
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== Testing ==
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== Compiling an Application for nu+ ==
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To test the code generation process, the [https://llvm.org/docs/TestingGuide.html LLVM testing infrastructure] has been used.
 
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The script "run_tests" can be used to run the nu+ testing suite. The main purpose is to perform regression tests, so that it is possible to determine if a change in the back-end has any negative consequence.
 
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The tool used is the "llvm-lit", a python script that parses the test files and executes the testing commands.
 
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The '''code generation tests''' are contained in "compiler/test/CodeGen/NuPlus" and cover the main LLVM IR operations. A code generation test file is a collection of functions written in LLVM IR with commands directed to the llvm-lit and [https://llvm.org/docs/CommandGuide/FileCheck.html FileCheck] tools. These commands are written as comments. The main commands used are '''RUN''', '''CHECK''', and '''CHECK-LABEL'''.
 
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The '''RUN''' line tells lit how to run the test. If there are no RUN lines, lit will issue an error while running a test. The line syntax is similar to a shell’s syntax for pipelines. To examine the output and check if the test has been passed, the FileCheck tool must be used.
 
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The RUN line used for all the tests is:
 
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<syntaxhighlight lang="c" line='line'>
 
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; RUN: llc -march=nuplus < %s | FileCheck %s
 
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</syntaxhighlight>
 
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This tells lit to run '''llc''' with nu+ architecture as target, to give the output file to the FileCheck tool.
 
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The '''CHECK_LABEL''' and the '''CHECK''' lines are interpreted by the FileCheck tool. It compares the llc output file with the '''CHECK_LABEL''' and '''CHECK''' lines. The comparison is done in sequence, although there are directives that let the checking not be performed in sequential order, see [https://llvm.org/docs/CommandGuide/FileCheck.html] for further details.
 
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== Libraries ==
 
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nu+ is provided with different kind of libraries that are contained in the libs/ folder. For more information, check [[libraries|The nu+ libraries]].
 
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== Makefiles and linker scripts ==
 
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TODO: completare
 
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== Debug and typical errors ==
 
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For more information about the debug support and some typical errors, check [[debugLLVM|How to debug LLVM]].
 
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== Compiler Extensions ==
 
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* [[OpenCL|OpenCL extension for the nu+ architecture]]
 
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* [[OpenMP|OpenMP extension for the nu+ architecture]]
 

Revision as of 11:17, 31 March 2019

The nu+ toolchain is a collection of tools required to compile a nu+ executable application. It is based on the LLVM project leveraging on a custom version of the Clang Frontend and on a from-scratch implementation of the Backend. The toolchain comes with a modified version of LLD, an elf2hex tool to generate nu+ compatible memory images and lastly a custom version of the objdump tool for debug purposes. A custom implementation of the libc libraries is provided.

The toolchain supports the compilation of C-based and OpenCL C kernels.

Building Toolchain on Ubuntu Linux environment

This section shows how to build the nu+ toolchain in an Ubuntu Linux environment. The following steps are still valid in any other Unix-based system despite of package manager related differences.

Required Software

The nu+ toolchain installation relies on the following dependencies:

  • Git
  • GCC
  • CMake
  • Python 2.7
  • libxml
  • Zlib
  • Bison
  • Flex
  • Libedit
  • Swig
  • ncurses libraries
  • Ninja

The following terminal command may be used to install all required software:

$ sudo apt install libxml2-dev git cmake gcc g++ python bison flex zlib1g-dev swig python-dev libedit-dev libncurses5-dev ninja

Building Process

First, you have to obtain the source code from the official repository by typing the following command:

$ git clone https://gitlab.com/catecio/NuPlusLLVM.git <clone_directory>

The repository contains a helper script, setup.sh to make easier the installation process. To build a new implementation of the nu+ toolchain just type:

$ ./setup.sh -n

This command starts the compilation process, installing the toolchain in Release Mode in /usr/local/llvm-nuplus. If a debug version is required, add the -d flag to setup.sh. You can also choose the number of threads for the compilation process, by using the -t=<number_of_threads> parameter.

At the end of the compilation process, libraries are required to be linked to the installation folder:

$ ./setup.sh -l

Now, you can use the toolchain to build your own application.

The nu+ LLVM Structure

The nu+ toolchain relies on the LLVM project, version 7.0, providing customized implementation of its libraries to make possible generating nu+ executable kernels.

Clang is the compiler frontend for nu+, extended to handle the token-recognition of custom intrinsic functions.

LLVM core libraries are used to implement a custom backend for nu+, to manage the code lowering on the target-device.

LLD is adapted to match nu+ architecture requirements for linking.

objdump is provided to disassemble and analyze the generated code.

elf2hex is a tool required for memory image generation.


Check the following links for detailed informations on how the toolchain is implemented.

Compiling an Application for nu+

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