[MemProf] Disable hot hints by default (#124338) By default we were marking some contexts as hot, and adding hot hints to unambiguously hot allocations. However, there is not yet support for cloning to expose hot allocation contexts, and none is planned for the forseeable future. While we convert hot contexts to notcold contexts during the cloning step, their existence was greatly limiting the context trimming performed when we add the MemProf profile to the IR. This change simply disables the generation of hot contexts / hints by default, as few allocations were unambiguously hot. A subsequent change will address the issue when hot hints are optionally enabled. See PR124219 for details. This change resulted in significant overhead reductions for a large target: ~48% reduction in the per-module ThinLTO bitcode summary sizes ~72% reduction in the distributed ThinLTO bitcode combined summary sizes ~68% reduction in thin link time ~34% reduction in thin link peak memory
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.
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.
Join the LLVM Discourse forums, Discord chat, LLVM Office Hours or Regular sync-ups.
The LLVM project has adopted a code of conduct for participants to all modes of communication within the project.