65e57bbed0
The import/export maps, and the ModuleToDefinedGVSummaries map, are all indexed by module paths, which are StringRef obtained from the module summary index, which already has a data structure than owns these strings (the ModulePathStringTable). Because these other maps are also StringMap, which makes a copy of the string key, we were keeping multiple extra copies of the module paths, leading to memory overhead. Change these to DenseMap keyed by StringRef, and document that the strings are owned by the index. The only exception is the llvm-link tool which synthesizes an import list from command line options, and I have added a string cache to maintain ownership there. I measured around 5% memory reduction in the thin link of a large binary. Differential Revision: https://reviews.llvm.org/D156580
The LLVM Compiler Infrastructure
Welcome to the LLVM project!
This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.
The LLVM project has multiple components. The core of the project is itself called "LLVM". This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer.
C-like languages use the Clang frontend. This component 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
Consult the Getting Started with LLVM page for information on building and running LLVM.
For information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.
Getting in touch
Join the LLVM Discourse forums, Discord chat, or #llvm IRC channel on OFTC.
The LLVM project has adopted a code of conduct for participants to all modes of communication within the project.