Implement opt-bisect-limit for mir

tests/run-make/mir-opt-bisect-limit/main.rs

@@ -0,0 +1,11 @@
+#![crate_type = "lib"]
+#![no_std]
+
+#[inline(never)]
+pub fn callee(x: u64) -> u64 {
+    x.wrapping_mul(3).wrapping_add(7)
+}
+
+pub fn caller(a: u64, b: u64) -> u64 {
+    callee(a) + callee(b)
+}

tests/run-make/mir-opt-bisect-limit/rmake.rs

@@ -0,0 +1,119 @@
+use std::path::Path;
+
+use run_make_support::{CompletedProcess, rfs, rustc};
+
+struct Case {
+    name: &'static str,
+    flags: &'static [&'static str],
+    expect_inline_dump: bool,
+    expect_running: ExpectedCount,
+    expect_not_running: ExpectedCount,
+}
+
+enum ExpectedCount {
+    Exactly(usize),
+    AtLeastOne,
+    Zero,
+}
+
+fn main() {
+    let cases = [
+        Case {
+            name: "limit0",
+            flags: &["-Zmir-opt-bisect-limit=0"],
+            expect_inline_dump: false,
+            expect_running: ExpectedCount::Exactly(0),
+            expect_not_running: ExpectedCount::AtLeastOne,
+        },
+        Case {
+            name: "limit1",
+            flags: &["-Zmir-opt-bisect-limit=1"],
+            expect_inline_dump: false,
+            expect_running: ExpectedCount::Exactly(1),
+            expect_not_running: ExpectedCount::AtLeastOne,
+        },
+        Case {
+            name: "huge_limit",
+            flags: &["-Zmir-opt-bisect-limit=1000000000"],
+            expect_inline_dump: true,
+            expect_running: ExpectedCount::AtLeastOne,
+            expect_not_running: ExpectedCount::Zero,
+        },
+        Case {
+            name: "limit0_with_force_enable_inline",
+            flags: &["-Zmir-opt-bisect-limit=0", "-Zmir-enable-passes=+Inline"],
+            expect_inline_dump: false,
+            expect_running: ExpectedCount::Exactly(0),
+            expect_not_running: ExpectedCount::AtLeastOne,
+        },
+    ];
+
+    for case in cases {
+        let (inline_dumped, running_count, not_running_count, output) =
+            compile_case(case.name, case.flags);
+
+        assert_eq!(
+            inline_dumped, case.expect_inline_dump,
+            "{}: unexpected Inline dump presence",
+            case.name
+        );
+
+        assert_expected_count(
+            running_count,
+            case.expect_running,
+            &format!("{}: running count", case.name),
+        );
+        assert_expected_count(
+            not_running_count,
+            case.expect_not_running,
+            &format!("{}: NOT running count", case.name),
+        );
+    }
+}
+
+fn compile_case(dump_dir: &str, extra_flags: &[&str]) -> (bool, usize, usize, CompletedProcess) {
+    if Path::new(dump_dir).exists() {
+        rfs::remove_dir_all(dump_dir);
+    }
+    rfs::create_dir_all(dump_dir);
+
+    let mut cmd = rustc();
+    cmd.input("main.rs")
+        .arg("--emit=mir")
+        .arg("-Zmir-opt-level=2")
+        .arg("-Copt-level=2")
+        .arg("-Zthreads=1")
+        .arg("-Zdump-mir=Inline")
+        .arg(format!("-Zdump-mir-dir={dump_dir}"));
+
+    for &flag in extra_flags {
+        cmd.arg(flag);
+    }
+
+    let output = cmd.run();
+    let (running_count, not_running_count) = bisect_line_counts(&output);
+    (has_inline_dump_file(dump_dir), running_count, not_running_count, output)
+}
+
+fn assert_expected_count(actual: usize, expected: ExpectedCount, context: &str) {
+    match expected {
+        ExpectedCount::Exactly(n) => assert_eq!(actual, n, "{context}"),
+        ExpectedCount::AtLeastOne => assert!(actual > 0, "{context}"),
+        ExpectedCount::Zero => assert_eq!(actual, 0, "{context}"),
+    }
+}
+
+fn has_inline_dump_file(dir: &str) -> bool {
+    rfs::read_dir(dir)
+        .flatten()
+        .any(|entry| entry.file_name().to_string_lossy().contains(".Inline."))
+}
+
+fn bisect_line_counts(output: &CompletedProcess) -> (usize, usize) {
+    let stderr = output.stderr_utf8();
+    let running_count =
+        stderr.lines().filter(|line| line.starts_with("BISECT: running pass (")).count();
+    let not_running_count =
+        stderr.lines().filter(|line| line.starts_with("BISECT: NOT running pass (")).count();
+    (running_count, not_running_count)
+}