| # llvm-exegesis |
| |
| `llvm-exegesis` is a benchmarking tool that accepts or generates snippets and |
| can measure characteristics of those snippets by executing it while keeping track |
| of performance counters. |
| |
| ### Currently Supported Platforms |
| |
| `llvm-exegesis` is quite platform-dependent and currently only supports a couple |
| platform configurations for benchmarking. The limitations are listed below. |
| Analysis mode in `llvm-exegesis` is supported on all platforms on which LLVM is. |
| |
| #### Currently Supported Operating Systems for Benchmarking |
| |
| Currently, `llvm-exegesis` only supports benchmarking on Linux. This is mainly |
| due to a dependency on the Linux perf subsystem for reading |
| performance counters. |
| |
| The subprocess execution mode and memory annotations currently only supports |
| Linux due to a heavy reliance on many Linux specific syscalls/syscall |
| implementations. |
| |
| #### Currently Supported Architectures for Benchmarking |
| |
| Currently, using `llvm-exegesis` for benchmarking is supported on the following |
| architectures: |
| * x86 |
| * 64-bit only due to this being the only implemented calling convention |
| in `llvm-exegesis` currently. |
| * ARM |
| * Very experimental AArch64 support only: most opcodes probably won't work as |
| e.g. pseudo instructions and most register classes are not supported. |
| * MIPS |
| * PowerPC (PowerPC64LE only) |
| * RISC-V |
| * RV64I/E, RV32I/E and extensions supported by LLVM's RISC-V backend with |
| some limitations. |
| |
| Note that not all benchmarking functionality is guaranteed to work on all platforms. |
| |
| Memory annotations are currently only supported on 64-bit X86. There is no |
| inherent limitations for porting memory annotations to other architectures, but |
| parts of the test harness are implemented as MCJITed assembly that is generated |
| in `./lib/X86/Target.cpp` that would need to be implemented on other architectures |
| to bring up support. |
