os-rust/tests/run-make/pgo-use/rmake.rs
2024-07-05 10:17:48 -04:00

54 lines
2.2 KiB
Rust

// This test makes sure that PGO profiling data leads to cold functions being
// marked as `cold` and hot functions with `inlinehint`.
// The test program contains an `if` where actual execution only ever takes the
// `else` branch. Accordingly, we expect the function that is never called to
// be marked as cold.
// See https://github.com/rust-lang/rust/pull/60262
//@ needs-profiler-support
//@ ignore-cross-compile
use run_make_support::{
cwd, find_files_by_prefix_and_extension, fs_wrapper, llvm_filecheck, llvm_profdata,
run_with_args, rustc,
};
fn main() {
// Compile the test program with instrumentation
// Disable the pre-inlining pass (i.e. a pass that does some inlining before
// it adds the profiling instrumentation). Disabling this pass leads to
// rather predictable IR which we need for this test to be stable.
rustc()
.opt_level("2")
.codegen_units(1)
.arg("-Cllvm-args=-disable-preinline")
.profile_generate(cwd())
.input("main.rs")
.run();
// Run it in order to generate some profiling data
run_with_args("main", &["some-argument"]);
// Postprocess the profiling data so it can be used by the compiler
llvm_profdata()
.merge()
.output("merged.profdata")
.input(find_files_by_prefix_and_extension(cwd(), "default", "profraw").get(0).unwrap())
.run();
// Compile the test program again, making use of the profiling data
rustc()
.opt_level("2")
.codegen_units(1)
.arg("-Cllvm-args=-disable-preinline")
.profile_use("merged.profdata")
.emit("llvm-ir")
.input("main.rs")
.run();
// Check that the generate IR contains some things that we expect
//
// We feed the file into LLVM FileCheck tool *in reverse* so that we see the
// line with the function name before the line with the function attributes.
// FileCheck only supports checking that something matches on the next line,
// but not if something matches on the previous line.
let mut bytes = fs_wrapper::read("interesting.ll");
bytes.reverse();
llvm_filecheck().patterns("filecheck-patterns.txt").stdin(bytes).run();
}