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Enable AutoFDO. This largely involves implementing the options debug-info-for-profiling and profile-sample-use and forwarding them on to LLVM. AutoFDO can be used on x86-64 Linux like this: rustc -O -Clink-arg='Wl,--no-rosegment' -Cdebug-info-for-profiling main.rs -o main perf record -b ./main create_llvm_prof --binary=main --out=code.prof rustc -O -Cprofile-sample-use=code.prof main.rs -o main2 Now `main2` will have feedback directed optimization applied to it. The create_llvm_prof tool can be obtained from this github repository: https://github.com/google/autofdo The option -Clink-arg='Wl,--no-rosegment' is necessary to avoid lld putting an extra RO segment before the executable code, which would make the binary silently incompatible with create_llvm_prof.
This directory currently contains some LLVM support code. This will generally be sent upstream to LLVM in time; for now it lives here. NOTE: the LLVM C++ ABI is subject to between-version breakage and must *never* be exposed to Rust. To allow for easy auditing of that, all Rust-exposed types must be typedef-ed as "LLVMXyz", or "LLVMRustXyz" if they were defined here. Functions that return a failure status and leave the error in the LLVM last error should return an LLVMRustResult rather than an int or anything to avoid confusion. When translating enums, add a single `Other` variant as the first one to allow for new variants to be added. It should abort when used as an input. All other types must not be typedef-ed as such.