Difference between revisions of "Toolchain"
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| − | The nu+ | + | The nu+ toolchain is a collection of tools required to compile a nu+ ''executable'' application. It is based on the [https://llvm.org LLVM] project leveraging on a custom version of the [[Frontend | Clang Frontend]] and on a ''from-scratch'' implementation of the [[Backend | backend]]. The toolchain comes with a modified version of [https://lld.llvm.org LLD], an '''elf2hex''' implementation to generate nu+ compatible memory images and lastly a custom version of the '''objdump''' tool for debug purposes. |
== Requirements for nu+ toolchain== | == Requirements for nu+ toolchain== | ||
Revision as of 16:49, 27 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 implementation to generate nu+ compatible memory images and lastly a custom version of the objdump tool for debug purposes.
Contents
Requirements for nu+ toolchain
- cmake (we tested cmake 3.7.2 downloaded from https://cmake.org/download/)
- flex (we tested flex 2.6.0 downloaded using the advanced packaging tool, i.e. apt-get)
- bison (we tested bison 3.0.4 downloaded using the advanced packaging tool, i.e. apt-get)
- libz-dev (downloaded using the advanced packaging tool, i.e. apt-get)
How to compile the the nu+ toolchain
To build the nu+ toolchain, you must launch ./setup_new.sh -n from a terminal in the compiler root folder. The script will create a new directory called build and will start building the compiler. By default the script tries to build the compiler using 4 threads. If you want to modify that, especially if your machine have less than 8GB of RAM, you can use the -t flag to specify the number of threads to use. Other information can be obtained by using the -h flag.
How to compile a kernel for the nu+ architecture
TODO: considerare rimuovere questo e spostarlo in nuova pagina (Writing nu+ applications)
Some kernels are provided with the standard release of the nu+ toolchain. We provide a makefile to compile these kernels for nu+. In case you want to add a new kernel, it is suggested to copy a kernel folder and replace C/C++ files with your own source code. Then, remember to modify the makefile updating the SRCS variable with the names of the C/C++ files you want to compile. When using these makefiles, different tools are called:
- Clang to emit the LLVM IR and the object files
- MCLINKER to handle the job of linking
- elf2hex to generate the HEX file from the ELF file
- llvm-objdump to generate the dump from the elf file
In order to change the optimization level of the compiler or any other flag, it is possible to modify the misc/NuPlus.mk (or misc/Makefile.nuplus if you are compiling a kernel for the MANGO project ) makefile.
How to compile the libraries for the nu+ architecture
To compile the libraries you only have to execute ./setup_new.sh -l from a terminal in the NuPlusLLVM root folder. The script will automatically build the libraries. Note that you must have compiled the nu+ compiler first.
The nu+ LLVM
The nu+ toolchain is based on the LLVM project and includes:
- A custom version of the Clang frontend
- A native nu+ backend
- Some external tools that are used by llvm, i.e. linker, disassembler, etc..
In addition, in order add the nu+ architecture inside llvm, a registration phase was required.
Testing
To test the code generation process, the LLVM testing infrastructure has been used.
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.
The tool used is the "llvm-lit", a python script that parses the test files and executes the testing commands.
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 FileCheck tools. These commands are written as comments. The main commands used are RUN, CHECK, and CHECK-LABEL.
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.
The RUN line used for all the tests is:
; RUN: llc -march=nuplus < %s | FileCheck %sThis tells lit to run llc with nu+ architecture as target, to give the output file to the FileCheck tool.
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 [1] for further details.
Libraries
nu+ is provided with different kind of libraries that are contained in the libs/ folder. For more information, check The nu+ libraries.
Makefiles and linker scripts
TODO: completare
Debug and typical errors
For more information about the debug support and some typical errors, check How to debug LLVM.
