liblls

liblls is a collection of utilities extracted from llvm's codebase that meet the following requirements:

• Generally useful for high performance programs.
• Don't have similar/identical alternatives in popular libraries (e.g. the standard library or boost).

Currently this includes the following modules (where module means header file or header-implementation pair).

• SmallVector<T, N>, in src/SmallVector.h and src/SmallVector.cpp
• llvm's custom casting and RTTI implementation (dyn_cast, isa, etc.), in src/Casting.h

Each of these modules is totally standalone and has no dependancies outside of the standard library.

Usage

The best way to use liblls is to pick which files you want from src, and drop them into your project. This is the intended way to use liblls, and is also the simplest.

You could also compile it as a static library and link with it, but even this is probably overdoing it, as the library would consist of a single object file containing a single function.

For documentation, consult llvm (the changes I've made were minimal), or read the comments in the code. Ambitious users could generate doxygen documentation from them, but it would be nearly identical to the existing llvm documentation.

Caveats

Before you use liblls, there are a few things you should note.

• liblls does not provide any exception-safety guarantee. This is due to the fact that LLVM is compiled, by default, with exceptions turned off. This only makes a difference for SmallVector.{h,cpp}, so if you only want Casting.h

  While eventually I'd like to add a strong exception-safety guarantee to SmallVector, I have not done so yet. If this matters to you, use std::vector.

This is not an issue for the code in Casting.h.

Requirements

LibLLS expects a minimally conformant C++11 compiler and standard library. Anything too advanced would rule out MSVC, which we want to support. API features that would require C++11 features are enabled by default, but may be turned off using a preprocessor flag. See the Customization section below for specifics.

Right now the only C++11-related thing we really need is an implementation of the <type_traits> header.

Supporting earlier versions of C++ is not a high priority, so if you want that I'll accept a pull request.

However, compatibility with up to date compilers who aren't totally C++11-conformant yet is a priority, and if you submit an issue relating to this I'll fix the problem (if I have access to that compiler).

Customization

liblls is configurable through the following preprocessor definitions and flags. These are intended

• LIBLLS_NO_NAMESPACE: don't put the liblls code in a namespace.

• LIBLLS_NAMESPACE: The namespace to use for the code in liblls. This defaults to lls (we don't use llvm to avoid clashing). This is ignored if LIBLLS_NO_NAMESPACE is set.

• LIBLLS_NO_CXX11: don't use any advanced c++11 features (standard library still must be c++11). Undefined by default.

• LIBLLS_NO_RVALUE_REFERENCES: Don't compile any functions which use rvalue references. Only applys to SmallVector.h, and is redundant if LIBLLS_NO_CXX11 is defined. Undefined by default.

• LIBLLS_NO_VARIADIC_TEMPLATES: Don't compile any functions which use variadic templates. Only applys to SmallVector.h, and is redundant if LIBLLS_NO_CXX11 is defined. Undefined by default.

• LIBLLS_NO_DELETED_FUNCTION: Don't use deleted functions to indicate... deleting... the function. Just make it private and unimplemented. This only applys to SmallVector.h and is redundant if LIBLLS_NO_CXX11 is defined. Undefined by default.

Run the tests

liblls borrows (steals) the its test files from llvm, so it has a fairly complete set of test files. You can compile and these using make run-tests. Or, equivalently, make test && ./build/test-runner.

Planned additions

Eventually I'll get around to adding the following modules from llvm to liblls. Don't hold your breath though. Bug me if this matters to you or if theres something else I should add.

• raw_ostream and friends, definitely.
• SmallSet<T,N>, and SmallPtrSet<T,N>. maybe. These would depend on SmallVector
• DenseMap<T>, DenseSet<T>, maybe. These would probably get some API changes (with regard to DenseMapInfo).

License

liblls is available under the same license as LLVM. This is included below for your viewing convenience.

To make it as convenient as possible to use liblls, and because the scope of my changes is miniscule, I claim no copyright over any code I've written or changes I've made as part of liblls.

==============================================================================
LLVM Release License
==============================================================================
University of Illinois/NCSA
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    LLVM Team

    University of Illinois at Urbana-Champaign

    http://llvm.org

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