.. _compilation-label:

Target Program Compilation
==========================

To execute a given program, ScEpTIC requires the LLVM IR of the source files enriched with debug information.
In principle, ScEpTIC supports any source language whose compiler works with the LLVM toolchain, such as C (clang) and rust (cargo).
However, we tested ScEpTIC only with clang.

Clang
-----
To produce the LLVM IR of your *source.c* file with clang, you need to compile it as follows::

    clang -emit-llvm -S -g source.c

where the *-g* option generates the debug information and the *--emit-llvm -S* options tells clang to produce the LLVM IR.
Note that in some systems you may need to write the full path of your ``clang-12.0`` binary instead of ``clang``.

Once the compilation step completes, clang outputs a *source.ll* file, that is, the LLVM IR file simulated by ScEpTIC during system emulation.

If you need to specify an optimization pass or an optimization level, you can also use such options when generating the LLVM IR with clang.

Clang - linking multiple files
------------------------------
If your project consists of multiple *.c* files, you need to compile all of them, as specified above.
Then, you need to link all the generated *.ll* files together using ``llvm-link`` or `lli`::

    llvm-link -S file1.ll file2.ll -o program.ll

where the *-S* option tells llvm-link to produce the LLVM IR and ``program.ll`` is the output file.
Note that in some systems you may need to write the full path of your ``llvm-link`` binary instead of ``llvm-link``.

Once the linking step completes, llvm-link outputs a *program.ll* file, that is, the LLVM IR file simulated by ScEpTIC during system emulation.