
In accordance with https://github.com/llvm/llvm-project/issues/123569 In order to keep the patch at reasonable size, this PR only covers for the llvm subproject, unittests excluded.
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.
- 64-bit only due to this being the only implemented calling convention
in
- 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)
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.