26ecf97895
Following on from #125058, this patch takes into account the work done in the vector early exit block when assessing the profitability of vectorising the loop. I have renamed areRuntimeChecksProfitable to isOutsideLoopWorkProfitable and we now pass in the early exit costs. As part of this, I have added the ExtractFirstActive opcode to VPInstruction::computeCost. It's worth pointing out that when we assess profitability of the loop we calculate a minimum trip count and compare that against the *maximum* trip count. However, since the loop has an early exit the runtime trip count can still end up being less than the minimum. Alternatively, we may never take the early exit at all at runtime and so we have the opposite problem of over-estimating the cost of the loop. The loop vectoriser cannot simultaneously take two contradictory positions and so I feel the only sensible thing to do is be conservative and assume the loop will be more expensive than loops without early exits. We may find in future that we need to adjust the cost according to the probability of taking the early exit. This will become even more important once we support multiple early exits. However, we have to start somewhere and we can always revisit this later.
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, 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.