Rollup merge of #133695 - x17jiri:hint_likely, r=Amanieu

Reexport likely/unlikely in std::hint

Since `likely`/`unlikely` should be working now, we could reexport them in `std::hint`. I'm not sure if this is already approved or if it requires approval

Tracking issue: #26179

3 files changed, 215 insertions, 0 deletions

diff --git a/tests/codegen/hint/cold_path.rs b/tests/codegen/hint/cold_path.rs
new file mode 100644
index 00000000000..dac72073f85
--- /dev/null
+++ b/tests/codegen/hint/cold_path.rs
@@ -0,0 +1,54 @@
+//@ compile-flags: -O
+#![crate_type = "lib"]
+#![feature(cold_path)]
+
+use std::hint::cold_path;
+
+#[inline(never)]
+#[no_mangle]
+pub fn path_a() {
+    println!("path a");
+}
+
+#[inline(never)]
+#[no_mangle]
+pub fn path_b() {
+    println!("path b");
+}
+
+#[no_mangle]
+pub fn test1(x: bool) {
+    if x {
+        path_a();
+    } else {
+        cold_path();
+        path_b();
+    }
+
+    // CHECK-LABEL: @test1(
+    // CHECK: br i1 %x, label %bb1, label %bb2, !prof ![[NUM:[0-9]+]]
+    // CHECK: bb2:
+    // CHECK: path_b
+    // CHECK: bb1:
+    // CHECK: path_a
+}
+
+#[no_mangle]
+pub fn test2(x: i32) {
+    match x > 0 {
+        true => path_a(),
+        false => {
+            cold_path();
+            path_b()
+        }
+    }
+
+    // CHECK-LABEL: @test2(
+    // CHECK: br i1 %_2, label %bb2, label %bb1, !prof ![[NUM]]
+    // CHECK: bb1:
+    // CHECK: path_b
+    // CHECK: bb2:
+    // CHECK: path_a
+}
+
+// CHECK: ![[NUM]] = !{!"branch_weights", {{(!"expected", )?}}i32 2000, i32 1}
diff --git a/tests/codegen/hint/likely.rs b/tests/codegen/hint/likely.rs
new file mode 100644
index 00000000000..2f589cc99d2
--- /dev/null
+++ b/tests/codegen/hint/likely.rs
@@ -0,0 +1,81 @@
+//@ compile-flags: -O
+#![crate_type = "lib"]
+#![feature(likely_unlikely)]
+
+use std::hint::likely;
+
+#[inline(never)]
+#[no_mangle]
+pub fn path_a() {
+    println!("path a");
+}
+
+#[inline(never)]
+#[no_mangle]
+pub fn path_b() {
+    println!("path b");
+}
+
+#[no_mangle]
+pub fn test1(x: bool) {
+    if likely(x) {
+        path_a();
+    } else {
+        path_b();
+    }
+
+    // CHECK-LABEL: @test1(
+    // CHECK: br i1 %x, label %bb2, label %bb3, !prof ![[NUM:[0-9]+]]
+    // CHECK: bb3:
+    // CHECK: path_b
+    // CHECK: bb2:
+    // CHECK: path_a
+}
+
+#[no_mangle]
+pub fn test2(x: i32) {
+    match likely(x > 0) {
+        true => path_a(),
+        false => path_b(),
+    }
+
+    // CHECK-LABEL: @test2(
+    // CHECK: br i1 %_2, label %bb2, label %bb3, !prof ![[NUM]]
+    // CHECK: bb3:
+    // CHECK: path_b
+    // CHECK: bb2:
+    // CHECK: path_a
+}
+
+#[no_mangle]
+pub fn test3(x: i8) {
+    match likely(x < 7) {
+        true => path_a(),
+        _ => path_b(),
+    }
+
+    // CHECK-LABEL: @test3(
+    // CHECK: br i1 %_2, label %bb2, label %bb3, !prof ![[NUM]]
+    // CHECK: bb3:
+    // CHECK: path_b
+    // CHECK: bb2:
+    // CHECK: path_a
+}
+
+#[no_mangle]
+pub fn test4(x: u64) {
+    match likely(x != 33) {
+        false => path_a(),
+        _ => path_b(),
+    }
+
+    // CHECK-LABEL: @test4(
+    // CHECK: br i1 %0, label %bb3, label %bb2, !prof ![[NUM2:[0-9]+]]
+    // CHECK: bb3:
+    // CHECK: path_a
+    // CHECK: bb2:
+    // CHECK: path_b
+}
+
+// CHECK: ![[NUM]] = !{!"branch_weights", {{(!"expected", )?}}i32 2000, i32 1}
+// CHECK: ![[NUM2]] = !{!"branch_weights", {{(!"expected", )?}}i32 1, i32 2000}
diff --git a/tests/codegen/hint/unlikely.rs b/tests/codegen/hint/unlikely.rs
new file mode 100644
index 00000000000..328533f3081
--- /dev/null
+++ b/tests/codegen/hint/unlikely.rs
@@ -0,0 +1,80 @@
+//@ compile-flags: -O
+#![crate_type = "lib"]
+#![feature(likely_unlikely)]
+
+use std::hint::unlikely;
+
+#[inline(never)]
+#[no_mangle]
+pub fn path_a() {
+    println!("path a");
+}
+
+#[inline(never)]
+#[no_mangle]
+pub fn path_b() {
+    println!("path b");
+}
+
+#[no_mangle]
+pub fn test1(x: bool) {
+    if unlikely(x) {
+        path_a();
+    } else {
+        path_b();
+    }
+
+    // CHECK-LABEL: @test1(
+    // CHECK: br i1 %x, label %bb2, label %bb4, !prof ![[NUM:[0-9]+]]
+    // CHECK: bb4:
+    // CHECK: path_b
+    // CHECK: bb2:
+    // CHECK: path_a
+}
+
+#[no_mangle]
+pub fn test2(x: i32) {
+    match unlikely(x > 0) {
+        true => path_a(),
+        false => path_b(),
+    }
+
+    // CHECK-LABEL: @test2(
+    // CHECK: br i1 %_2, label %bb2, label %bb4, !prof ![[NUM]]
+    // CHECK: bb4:
+    // CHECK: path_b
+    // CHECK: bb2:
+    // CHECK: path_a
+}
+
+#[no_mangle]
+pub fn test3(x: i8) {
+    match unlikely(x < 7) {
+        true => path_a(),
+        _ => path_b(),
+    }
+
+    // CHECK-LABEL: @test3(
+    // CHECK: br i1 %_2, label %bb2, label %bb4, !prof ![[NUM]]
+    // CHECK: bb4:
+    // CHECK: path_b
+    // CHECK: bb2:
+    // CHECK: path_a
+}
+
+#[no_mangle]
+pub fn test4(x: u64) {
+    match unlikely(x != 33) {
+        false => path_a(),
+        _ => path_b(),
+    }
+
+    // CHECK-LABEL: @test4(
+    // CHECK: br i1 %0, label %bb4, label %bb2, !prof ![[NUM2:[0-9]+]]
+    // CHECK: bb4:
+    // CHECK: path_a
+    // CHECK: bb2:
+    // CHECK: path_b
+}
+
+// CHECK: ![[NUM]] = !{!"branch_weights", {{(!"expected", )?}}i32 1, i32 2000}