Always use llvm.used for coverage symbols

This follows what clang does in CoverageMappingGen. Using just
llvm.compiler.used is insufficient at least for MSVC targets.

2 files changed, 10 insertions, 10 deletions

diff --git a/compiler/rustc_codegen_ssa/src/traits/misc.rs b/compiler/rustc_codegen_ssa/src/traits/misc.rs
index 46f2adbe552..4266e42ec2b 100644
--- a/compiler/rustc_codegen_ssa/src/traits/misc.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/misc.rs
@@ -16,9 +16,11 @@ pub trait MiscMethods<'tcx>: BackendTypes {
     fn sess(&self) -> &Session;
     fn codegen_unit(&self) -> &'tcx CodegenUnit<'tcx>;
     fn used_statics(&self) -> &RefCell<Vec<Self::Value>>;
+    fn compiler_used_statics(&self) -> &RefCell<Vec<Self::Value>>;
     fn set_frame_pointer_type(&self, llfn: Self::Function);
     fn apply_target_cpu_attr(&self, llfn: Self::Function);
     fn create_used_variable(&self);
+    fn create_compiler_used_variable(&self);
     /// Declares the extern "C" main function for the entry point. Returns None if the symbol already exists.
     fn declare_c_main(&self, fn_type: Self::Type) -> Option<Self::Function>;
 }
diff --git a/compiler/rustc_codegen_ssa/src/traits/statics.rs b/compiler/rustc_codegen_ssa/src/traits/statics.rs
index 817fc02d166..a2a3cb56c78 100644
--- a/compiler/rustc_codegen_ssa/src/traits/statics.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/statics.rs
@@ -6,17 +6,15 @@ pub trait StaticMethods: BackendTypes {
     fn static_addr_of(&self, cv: Self::Value, align: Align, kind: Option<&str>) -> Self::Value;
     fn codegen_static(&self, def_id: DefId, is_mutable: bool);
 
-    /// Mark the given global value as "used", to prevent a backend from potentially removing a
-    /// static variable that may otherwise appear unused.
-    ///
-    /// Static variables in Rust can be annotated with the `#[used]` attribute to direct the `rustc`
-    /// compiler to mark the variable as a "used global".
-    ///
-    /// ```no_run
-    /// #[used]
-    /// static FOO: u32 = 0;
-    /// ```
+    /// Mark the given global value as "used", to prevent the compiler and linker from potentially
+    /// removing a static variable that may otherwise appear unused.
     fn add_used_global(&self, global: Self::Value);
+
+    /// Same as add_used_global(), but only prevent the compiler from potentially removing an
+    /// otherwise unused symbol. The linker is still permitted to drop it.
+    ///
+    /// This corresponds to the semantics of the `#[used]` attribute.
+    fn add_compiler_used_global(&self, global: Self::Value);
 }
 
 pub trait StaticBuilderMethods: BackendTypes {