Rollup merge of #113355 - Zalathar:ssa, r=oli-obk

Move most coverage code out of `rustc_codegen_ssa`

*This is one step in my larger coverage refactoring ambitions described at <https://github.com/rust-lang/compiler-team/issues/645>.*

The backend implementation of coverage instrumentation was originally split between SSA and LLVM, perhaps in the hopes that it could be used by other backends.

In practice, this split mostly just makes the coverage implementation harder to navigate and harder to modify. It seems unlikely that any backend will actually implement coverage instrumentation in the foreseeable future, especially since many parts of the existing implementation (outside the LLVM backend) are heavily tied to the specific details of LLVM's coverage instrumentation features.

The current shared implementation of `codegen_coverage` is heavily tied to the details of `StatementKind::Coverage`, which makes those details difficult to change. I have reason to want to change those details as part of future fixes/improvements, so this will reduce the amount of interface churn caused by those later changes.

---

This is intended to be a pure refactoring change, with no changes to actual behaviour. All of the “added” code has really just been moved from other files.

1 files changed, 3 insertions, 61 deletions

diff --git a/compiler/rustc_codegen_gcc/src/coverageinfo.rs b/compiler/rustc_codegen_gcc/src/coverageinfo.rs
index 872fc2472e2..849e9886ef3 100644
--- a/compiler/rustc_codegen_gcc/src/coverageinfo.rs
+++ b/compiler/rustc_codegen_gcc/src/coverageinfo.rs
@@ -1,69 +1,11 @@
-use gccjit::RValue;
-use rustc_codegen_ssa::traits::{CoverageInfoBuilderMethods, CoverageInfoMethods};
-use rustc_hir::def_id::DefId;
-use rustc_middle::mir::coverage::{
-    CodeRegion,
-    CounterValueReference,
-    ExpressionOperandId,
-    InjectedExpressionId,
-    Op,
-};
+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 set_function_source_hash(
-        &mut self,
-        _instance: Instance<'tcx>,
-        _function_source_hash: u64,
-    ) -> bool {
-        unimplemented!();
-    }
-
-    fn add_coverage_counter(&mut self, _instance: Instance<'tcx>, _id: CounterValueReference, _region: CodeRegion) -> bool {
-        // TODO(antoyo)
-        false
-    }
-
-    fn add_coverage_counter_expression(&mut self, _instance: Instance<'tcx>, _id: InjectedExpressionId, _lhs: ExpressionOperandId, _op: Op, _rhs: ExpressionOperandId, _region: Option<CodeRegion>) -> bool {
-        // TODO(antoyo)
-        false
-    }
-
-    fn add_coverage_unreachable(&mut self, _instance: Instance<'tcx>, _region: CodeRegion) -> bool {
+    fn add_coverage(&mut self, _instance: Instance<'tcx>, _coverage: &Coverage) {
         // TODO(antoyo)
-        false
-    }
-}
-
-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!();
     }
 }