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This is an Ada compiler based on LLVM, connecting the GNAT front-end to theLLVM code generator to generate LLVM bitcode for Ada and to open the LLVMecosystem to Ada.

Note that we are not planning on replacing any existing GNAT port that'sbased on GCC: this project is meant to provide additional, not replacement,GNAT ports.

You are welcome to experiment with this technology and providefeedback on successes, usages, limitations, pull requests, etc.

• For more information on LLVM, seellvm.org.
• For more information on GNAT, seeadacore.com.

To build GNAT LLVM from sources, follow these steps:

• First do a checkout of this repository and go to this directory:

  $ git clone https://github.com/AdaCore/gnat-llvm.git$ cd gnat-llvm

• Then obtain a check out of the latest GNAT sources from gcc.gnu.org underthe llvm-interface directory:

  $ git clone git://gcc.gnu.org/git/gcc.git llvm-interface/gcc

  then under non Windows systems:

  $ ln -s gcc/gcc/ada llvm-interface/gnat_src

  under Windows systems:

  $ mv llvm-interface/gcc/gcc/ada llvm-interface/gnat_src

• Install (and put in your PATH) a recent GNAT, e.g GNAT Community 2021or GCC 11.

• Install LLVM and Clang 16.0.x

  The recommended way to build GNAT LLVM is to use an existing LLVM andclang package installed via e.g. "brew install llvm" on Mac OS or "sudoapt-get install llvm-dev" on Ubuntu. You can also build llvm yourself withthe options that suit your needs. After installing/building, make sure thellvm bin directory containing llvm-config and clang is in your PATH.

  An alternative only suitable for core GNAT LLVM development on x86 nativeconfigurations is to use the following command, assuming you have cmakeversion >= 3.13.4 in your path:

  $ make llvm

  Note that there's currently a bug in LLVM's aliasing handling. We checkfor it and generate slightly pessimized code in that case, but a patchto be applied to LLVM's lib/Analyze directory is in the filellvm/patches/LLVMStructTBAAPatch.diff.

• Finally build GNAT LLVM:

  $ make

This creates a "ready to use" set of directories "bin" and "lib" underllvm-interface which you can put in your PATH:

PATH=$PWD/llvm-interface/bin:$PATH

• If you want in addition to generate bitcode for the GNAT runtime, you can do:

  $ make gnatlib-bc

  This will generate libgnat.bc and libgnarl.bc in the adalib directory, alongwith libgnat.a and libgnarl.a.

• To run the compiler and produce a native object file:

  $ llvm-gcc -c file.adb

• To debug the compiler:

  $ gdb -args llvm-gnat1 -c file.adb

• To build a complete native executable:

  $ llvm-gnatmake main.adb

• To build a whole project:

  $ gprbuild --target=llvm -Pprj ...

• To generate LLVM bitcode (will generate a .bc file):

  $ llvm-gcc -c -emit-llvm file.adb

• To generate LLVM assembly (will generate a .ll file):

  $ llvm-gcc -c -S -emit-llvm file.adb

• To generate native assembly file (will generate a .s file):

  $ llvm-gcc -S file.adb

The GNAT LLVM tool is licensed under the GNU General Public License version 3or later; see fileCOPYING3 for details.