[ORC] Replace ORC's baked-in dependence tracking with WaitingOnGraph. (#163027)
WaitingOnGraph tracks waiting-on relationships between nodes (intended
to represent symbols in an ORC program) in order to identify nodes that
are *Ready* (i.e. are not waiting on any other nodes) or have *Failed*
(are waiting on some node that cannot be produced).
WaitingOnGraph replaces ORC's baked-in data structures that were
tracking the same information (EmissionDepUnit, EmissionDepUnitInfo,
...). Isolating this information in a separate data structure simplifies
the code, allows us to unit test it, and simplifies performance testing.
The WaitingOnGraph uses several techniques to improve performance
relative to the old data structures, including symbol coalescing
("SuperNodes") and symbol keys that don't perform unnecessary reference
counting (NonOwningSymbolStringPtr).
This commit includes unit tests for common dependence-tracking issues
that have led to ORC bugs in the past.
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.