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Linker Design

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Bugs

lld bugs should be reported at the LLVM Bugzilla.

lld - The LLVM Linker

lld is a new set of modular code for creating linker tools.

  • End-User Features:
    • Compatible with existing linker options
    • Reads standard Object Files (e.g. ELF, Mach-O, PE/COFF)
    • Writes standard Executable Files (e.g. ELF, Mach-O, PE)
    • Fast link times
    • Minimal memory use
    • Remove clang’s reliance on “the system linker”
    • Uses the LLVM “UIUC” BSD-Style license.
  • Applications:
    • Modular design
    • Support cross linking
    • Easy to add new CPU support
    • Can be built as static tool or library
  • Design and Implementation:
    • Extensive unit tests
    • Internal linker model can be dumped/read to textual format
    • Internal linker model can be dumped/read to a new native format
    • Native format designed to be fast to read and write
    • Additional linking features can be plugged in as “passes”
    • OS specific and CPU specific code factored out

Why a new linker?

The fact that clang relies on whatever linker tool you happen to have installed means that clang has been very conservative adopting features which require a recent linker.

In the same way that the MC layer of LLVM has removed clang’s reliance on the system assembler tool, the lld project will remove clang’s reliance on the system linker tool.

Current Status

lld can self host on x86-64 FreeBSD and Linux and x86 Windows.

All SingleSource tests in test-suite pass on x86-64 Linux.

All SingleSource and MultiSource tests in the LLVM test-suite pass on MIPS 32-bit little-endian Linux.

Source

lld is available in the LLVM SVN repository:

svn co http://llvm.org/svn/llvm-project/lld/trunk

lld is also available via the read-only git mirror:

git clone http://llvm.org/git/lld.git

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