formatted docs | msvc-opt-minsize.rs

Author: Kivooeo

tests/ui/codegen/msvc-opt-level-z-no-corruption.rs

@@ -1,12 +1,18 @@
-// A previously outdated version of LLVM caused compilation failures on Windows
-// specifically with optimization level `z`. After the update to a more recent LLVM
-// version, this test checks that compilation and execution both succeed.
-// See https://github.com/rust-lang/rust/issues/45034
+//! Test that opt-level=z produces correct code on Windows MSVC targets.
+//!
+//! A previously outdated version of LLVM caused compilation failures and
+//! generated invalid code on Windows specifically with optimization level `z`.
+//! The bug manifested as corrupted base pointers due to incorrect register
+//! usage in the generated assembly (e.g., `popl %esi` corrupting local variables).
+//! After updating to a more recent LLVM version, this test ensures that
+//! compilation and execution both succeed with opt-level=z.
+//!
+//! Regression test for <https://github.com/rust-lang/rust/issues/45034>.
 
 //@ ignore-cross-compile
 // Reason: the compiled binary is executed
 //@ only-windows
-// Reason: the observed bug only occurs on Windows
+// Reason: the observed bug only occurred on Windows MSVC targets
 //@ run-pass
 //@ compile-flags: -C opt-level=z
 
@@ -20,8 +26,8 @@ fn foo(x: i32, y: i32) -> i64 {
 #[inline(never)]
 fn bar() {
     let _f = Box::new(0);
-    // This call used to trigger an LLVM bug in opt-level z where the base
-    // pointer gets corrupted, see issue #45034
+    // This call used to trigger an LLVM bug in opt-level=z where the base
+    // pointer gets corrupted due to incorrect register allocation
     let y: fn(i32, i32) -> i64 = test::black_box(foo);
     test::black_box(y(1, 2));
 }