[llvm-dev] A libc in LLVM
Siva Chandra via llvm-dev
llvm-dev at lists.llvm.org
Mon Sep 16 15:05:16 PDT 2019
I would like to announce that we now have dedicated mailing lists for the
1. libc-dev - https://lists.llvm.org/cgi-bin/mailman/listinfo/libc-dev
2. libc-commits -
A brief README.txt and LICENSE.txt have been added:
I will soon share or put out design docs and code for review, as suitable.
On Thu, Aug 15, 2019 at 11:23 AM Siva Chandra <sivachandra at google.com>
> Hello again,
> I have now committed a proposal for this new libc:
> https://reviews.llvm.org/D64939. This proposal is based on the charter
> I shared previously (see below).
> Though it is now committed, if there are any concerns still, I am open
> to iterating until the community in general is satisfied with the
> Siva Chandra
> On Fri, Jul 12, 2019 at 8:15 AM Siva Chandra <sivachandra at google.com>
> > "llvm-libc" C Standard Library
> > ========================
> > llvm-libc is an implementation of the C standard library targeting C11
> > and above. It also provides platform specific extensions as relevant.
> > For example, on Linux it also provides pthreads, librt and other POSIX
> > extension libraries.
> > Documentation
> > ============
> > The llvm-libc project is still in the planning phase. Stay tuned for
> > updates soon.
> > Features and Goals
> > ================
> > * C11 and upwards conformant.
> > * A modular libc with individual pieces implemented in the "as a
> > library" philosophy of the LLVM project.
> > * Ability to layer this libc over the system libc.
> > * Provide C symbols as specified by the standards, but take advantage
> > and use C++ language facilities for the core implementation.
> > * Provides POSIX extensions on POSIX compliant platforms.
> > * Provides system-specific extensions as appropriate. For example,
> > provides the Linux API on Linux.
> > * Vendor extensions if and only if necessary.
> > * Designed and developed from the start to work with LLVM tooling and
> > testing like fuzz testing and sanitizer-supported testing.
> > * ABI independent implementation as far as possible.
> > * Use source based implementations as far possible rather than
> > assembly. Will try to “fix” the compiler rather than use assembly
> > language workarounds.
> > Why a new C Standard Library?
> > =========================
> > Implementing a libc is no small task and is not be taken lightly. A
> > natural question to ask is, "why a new implementation of the C
> > standard library?" There is no single answer to this question, but
> > some of the major reasons are as follows:
> > * Most libc implementations are monolithic. It is a non-trivial
> > porting task to pick and choose only the pieces relevant to one's
> > platform. The new libc will be developed with sufficient modularity to
> > make picking and choosing a straightforward task.
> > * Most libc implementations break when built with sanitizer specific
> > compiler options. The new libc will be developed from the start to
> > work with those specialized compiler options.
> > * The new libc will be developed to support and employ fuzz testing
> > from the start.
> > * Most libc implementations use a good amount of assembly language,
> > and assume specific ABIs (may be platform dependent). With the new
> > libc implementation, we want to use normal source code as much as
> > possible so that compiler-based changes to the ABI are easy. Moreover,
> > as part of the LLVM project, we want to use this opportunity to fix
> > performance related compiler bugs rather than using assembly
> > workarounds.
> > * A large hole in the llvm toolchain will be plugged with this new
> > libc. With the broad platform expertise in the LLVM community, and the
> > strong license and project structure, we think that the new libc will
> > be more tunable and robust, without sacrificing the simplicity and
> > accessibility typical of the LLVM project.
> > Platform Support
> > ==============
> > llvm-libc development is still in the planning phase. However, we
> > envision that it will support a variety of platforms in the coming
> > years. Interested parties are encouraged to participate in the design
> > and implementation, and add support for their favorite platforms.
> > Current Status
> > ============
> > llvm-libc development is still in the planning phase.
> > Build Bots
> > =========
> > Coming soon.
> > Get involved!
> > ===========
> > First please review our Developer's Policy. Stay tuned for llvm-libc
> > specific information.
> > Design Documents
> > ===============
> > Coming soon.
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