Remove trait CoverageInfoMethods, since non-LLVM backends don't need it

These methods are only ever called from within `rustc_codegen_llvm`, so they
can just be declared there as well.

Author: Zalathar

compiler/rustc_codegen_gcc/src/coverageinfo.rs

@@ -1,44 +1,11 @@
-use gccjit::RValue;
-use rustc_codegen_ssa::traits::{CoverageInfoBuilderMethods, CoverageInfoMethods};
-use rustc_hir::def_id::DefId;
+use rustc_codegen_ssa::traits::CoverageInfoBuilderMethods;
 use rustc_middle::mir::Coverage;
 use rustc_middle::ty::Instance;
 
 use crate::builder::Builder;
-use crate::context::CodegenCx;
 
 impl<'a, 'gcc, 'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
     fn add_coverage(&mut self, _instance: Instance<'tcx>, _coverage: &Coverage) {
         // TODO(antoyo)
     }
 }
-
-impl<'gcc, 'tcx> CoverageInfoMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
-    fn coverageinfo_finalize(&self) {
-        // TODO(antoyo)
-    }
-
-    fn get_pgo_func_name_var(&self, _instance: Instance<'tcx>) -> RValue<'gcc> {
-        unimplemented!();
-    }
-
-    /// Functions with MIR-based coverage are normally codegenned _only_ if
-    /// called. LLVM coverage tools typically expect every function to be
-    /// defined (even if unused), with at least one call to LLVM intrinsic
-    /// `instrprof.increment`.
-    ///
-    /// Codegen a small function that will never be called, with one counter
-    /// that will never be incremented.
-    ///
-    /// For used/called functions, the coverageinfo was already added to the
-    /// `function_coverage_map` (keyed by function `Instance`) during codegen.
-    /// But in this case, since the unused function was _not_ previously
-    /// codegenned, collect the coverage `CodeRegion`s from the MIR and add
-    /// them. The first `CodeRegion` is used to add a single counter, with the
-    /// same counter ID used in the injected `instrprof.increment` intrinsic
-    /// call. Since the function is never called, all other `CodeRegion`s can be
-    /// added as `unreachable_region`s.
-    fn define_unused_fn(&self, _def_id: DefId) {
-        unimplemented!();
-    }
-}

compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs

@@ -4,7 +4,7 @@ use crate::llvm;
 
 use llvm::coverageinfo::CounterMappingRegion;
 use rustc_codegen_ssa::coverageinfo::map::{Counter, CounterExpression};
-use rustc_codegen_ssa::traits::{ConstMethods, CoverageInfoMethods};
+use rustc_codegen_ssa::traits::ConstMethods;
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefId;

compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs

@@ -8,8 +8,8 @@ use libc::c_uint;
 use llvm::coverageinfo::CounterMappingRegion;
 use rustc_codegen_ssa::coverageinfo::map::{CounterExpression, FunctionCoverage};
 use rustc_codegen_ssa::traits::{
-    BaseTypeMethods, BuilderMethods, ConstMethods, CoverageInfoBuilderMethods, CoverageInfoMethods,
-    MiscMethods, StaticMethods,
+    BaseTypeMethods, BuilderMethods, ConstMethods, CoverageInfoBuilderMethods, MiscMethods,
+    StaticMethods,
 };
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir as hir;
@@ -54,11 +54,17 @@ impl<'ll, 'tcx> CrateCoverageContext<'ll, 'tcx> {
     }
 }
 
-impl<'ll, 'tcx> CoverageInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
-    fn coverageinfo_finalize(&self) {
+// These methods used to be part of trait `CoverageInfoMethods`, which no longer
+// exists after most coverage code was moved out of SSA.
+impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
+    pub(crate) fn coverageinfo_finalize(&self) {
         mapgen::finalize(self)
     }
 
+    /// For LLVM codegen, returns a function-specific `Value` for a global
+    /// string, to hold the function name passed to LLVM intrinsic
+    /// `instrprof.increment()`. The `Value` is only created once per instance.
+    /// Multiple invocations with the same instance return the same `Value`.
     fn get_pgo_func_name_var(&self, instance: Instance<'tcx>) -> &'ll llvm::Value {
         if let Some(coverage_context) = self.coverage_context() {
             debug!("getting pgo_func_name_var for instance={:?}", instance);

compiler/rustc_codegen_ssa/src/traits/coverageinfo.rs

@@ -1,25 +1,7 @@
 use super::BackendTypes;
-use rustc_hir::def_id::DefId;
 use rustc_middle::mir::Coverage;
 use rustc_middle::ty::Instance;
 
-pub trait CoverageInfoMethods<'tcx>: BackendTypes {
-    fn coverageinfo_finalize(&self);
-
-    /// Codegen a small function that will never be called, with one counter
-    /// that will never be incremented, that gives LLVM coverage tools a
-    /// function definition it needs in order to resolve coverage map references
-    /// to unused functions. This is necessary so unused functions will appear
-    /// as uncovered (coverage execution count `0`) in LLVM coverage reports.
-    fn define_unused_fn(&self, def_id: DefId);
-
-    /// For LLVM codegen, returns a function-specific `Value` for a global
-    /// string, to hold the function name passed to LLVM intrinsic
-    /// `instrprof.increment()`. The `Value` is only created once per instance.
-    /// Multiple invocations with the same instance return the same `Value`.
-    fn get_pgo_func_name_var(&self, instance: Instance<'tcx>) -> Self::Value;
-}
-
 pub trait CoverageInfoBuilderMethods<'tcx>: BackendTypes {
     /// Handle the MIR coverage info in a backend-specific way.
     ///

compiler/rustc_codegen_ssa/src/traits/mod.rs

@@ -33,7 +33,7 @@ pub use self::asm::{AsmBuilderMethods, AsmMethods, GlobalAsmOperandRef, InlineAs
 pub use self::backend::{Backend, BackendTypes, CodegenBackend, ExtraBackendMethods};
 pub use self::builder::{BuilderMethods, OverflowOp};
 pub use self::consts::ConstMethods;
-pub use self::coverageinfo::{CoverageInfoBuilderMethods, CoverageInfoMethods};
+pub use self::coverageinfo::CoverageInfoBuilderMethods;
 pub use self::debuginfo::{DebugInfoBuilderMethods, DebugInfoMethods};
 pub use self::declare::PreDefineMethods;
 pub use self::intrinsic::IntrinsicCallMethods;
@@ -59,7 +59,6 @@ pub trait CodegenMethods<'tcx>:
     + MiscMethods<'tcx>
     + ConstMethods<'tcx>
     + StaticMethods
-    + CoverageInfoMethods<'tcx>
     + DebugInfoMethods<'tcx>
     + AsmMethods<'tcx>
     + PreDefineMethods<'tcx>
@@ -75,7 +74,6 @@ impl<'tcx, T> CodegenMethods<'tcx> for T where
         + MiscMethods<'tcx>
         + ConstMethods<'tcx>
         + StaticMethods
-        + CoverageInfoMethods<'tcx>
         + DebugInfoMethods<'tcx>
         + AsmMethods<'tcx>
         + PreDefineMethods<'tcx>