The LLVM Compiler Infrastructure

This directory and its subdirectories contain source code for LLVM,a toolkit for the construction of highly optimized compilers,optimizers, and runtime environments.

Getting Started with the LLVM System

Taken from https://llvm.org/docs/GettingStarted.html.

Overview

Welcome to the LLVM project!

The LLVM project has multiple components. The core of the project isitself called "LLVM". This contains all of the tools, libraries, and headerfiles needed to process intermediate representations and converts it intoobject files. Tools include an assembler, disassembler, bitcode analyzer, andbitcode optimizer. It also contains basic regression tests.

C-like languages use the Clang front end. Thiscomponent compiles C, C++, Objective C, and Objective C++ code into LLVM bitcode-- and from there into object files, using LLVM.

Other components include:the libc++ C++ standard library,the LLD linker, and more.

Getting the Source Code and Building LLVM

The LLVM Getting Started documentation may be out of date. The ClangGetting Started page might have moreaccurate information.

This is an example workflow and configuration to get and build the LLVM source:

1. Checkout LLVM (including related subprojects like Clang):

   • git clone https://github.com/llvm/llvm-project.git

   • Or, on windows, git clone --config core.autocrlf=false https://github.com/llvm/llvm-project.git

2. Configure and build LLVM and Clang:

   • cd llvm-project

   • mkdir build

   • cd build

   • cmake -G <generator> [options] ../llvm

     Some common generators are:

     • Ninja --- for generating Ninjabuild files. Most llvm developers use Ninja.
     • Unix Makefiles --- for generating make-compatible parallel makefiles.
     • Visual Studio --- for generating Visual Studio projects andsolutions.
     • Xcode --- for generating Xcode projects.

     Some Common options:

     • -DLLVM_ENABLE_PROJECTS='...' --- semicolon-separated list of the LLVMsubprojects you'd like to additionally build. Can include any of: clang,clang-tools-extra, libcxx, libcxxabi, libunwind, lldb, compiler-rt, lld,polly, or debuginfo-tests.

       For example, to build LLVM, Clang, libcxx, and libcxxabi, use-DLLVM_ENABLE_PROJECTS="clang;libcxx;libcxxabi".

     • -DCMAKE_INSTALL_PREFIX=directory --- Specify for directory the fullpathname of where you want the LLVM tools and libraries to be installed(default /usr/local).

     • -DCMAKE_BUILD_TYPE=type --- Valid options for type are Debug,Release, RelWithDebInfo, and MinSizeRel. Default is Debug.

     • -DLLVM_ENABLE_ASSERTIONS=On --- Compile with assertion checks enabled(default is Yes for Debug builds, No for all other build types).

   • Run your build tool of choice!

     • The default target (i.e. ninja or make) will build all of LLVM.

     • The check-all target (i.e. ninja check-all) will run theregression tests to ensure everything is in working order.

     • CMake will generate build targets for each tool and library, and mostLLVM sub-projects generate their own check-<project> target.

     • Running a serial build will be slow. To improve speed, try running aparallel build. That's done by default in Ninja; for make, usemake -j NNN (NNN is the number of parallel jobs, use e.g. number ofCPUs you have.)

   • For more information see CMake

Consult theGetting Started with LLVMpage for detailed information on configuring and compiling LLVM. You can visitDirectory Layoutto learn about the layout of the source code tree.

credits

本仓库的porting的原始代码，commit来自llvm官方

commit 79b773fe7fffbea3bee2b34ace8f8ca5bae8526d 移植自 AllocAndInit/ollvm5.0.1 （该项目中stringobfuscation部分代码和 GoSSIP-SJTU/Armariris比较接近）

感谢AllocAndInit，GoSSIP-SJTU等开源的贡献！

使用方式

控制流平展功能

• -mllvm -fla: activates control flow flattening
• -mllvm -split: activates basic block splitting. Improve the flattening when applied together.
• -mllvm -split_num=3: if the pass is activated, applies it 3 times on each basic block. Default: 1

混淆控制流

• -mllvm -bcf: activates the bogus control flow pass
• -mllvm -bcf_loop=3: if the pass is activated, applies it 3 times on a function. Default: 1
• -mllvm -bcf_prob=40: if the pass is activated, a basic bloc will be obfuscated with a probability of 40%. Default: 30

指令替换

• -mllvm -sub: activate instructions substitution
• -mllvm -sub_loop=3: if the pass is activated, applies it 3 times on a function