[clang][perf-training] Support excluding LLVM build from PGO training (#126876) Using LLVM build itself for PGO training is convenient and a great starting point but it also has several issues: * LLVM build implicitly depends on tools other than CMake and C/C++ compiler and if those tools aren't available in PATH, the build will fail. * LLVM build also requires standard headers and libraries which may not always be available in the default location requiring an explicit sysroot. * Building a single configuration (-DCMAKE_BUILD_TYPE=Release) only exercises the -O3 pipeline and can pesimize other configurations. * Building for the host target doesn't exercise all other targets. * Since LLVMSupport is a static library, this doesn't exercise the linker (beyond what the CMake itself does). Rather than using LLVM build, ideally we would provide a more minimal, purpose built corpus. While we're working on building such a corpus, provide a CMake option that lets vendors disable the use LLVM build for PGO training.
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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.
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