coverage: Give the instrumentor its own counter type, separate from MIR

This splits off `BcbCounter` from MIR's `CoverageKind`, allowing the two types
to evolve in different directions as necessary.

5 files changed, 129 insertions, 85 deletions

diff --git a/compiler/rustc_middle/src/mir/coverage.rs b/compiler/rustc_middle/src/mir/coverage.rs
index d7d6e3a0086..1efb54bdb08 100644
--- a/compiler/rustc_middle/src/mir/coverage.rs
+++ b/compiler/rustc_middle/src/mir/coverage.rs
@@ -96,21 +96,6 @@ pub enum CoverageKind {
     Unreachable,
 }
 
-impl CoverageKind {
-    pub fn as_operand(&self) -> Operand {
-        use CoverageKind::*;
-        match *self {
-            Counter { id, .. } => Operand::Counter(id),
-            Expression { id, .. } => Operand::Expression(id),
-            Unreachable => bug!("Unreachable coverage cannot be part of an expression"),
-        }
-    }
-
-    pub fn is_expression(&self) -> bool {
-        matches!(self, Self::Expression { .. })
-    }
-}
-
 impl Debug for CoverageKind {
     fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
         use CoverageKind::*;
diff --git a/compiler/rustc_mir_transform/src/coverage/counters.rs b/compiler/rustc_mir_transform/src/coverage/counters.rs
index d1f2f0c76c8..3eca2610de6 100644
--- a/compiler/rustc_mir_transform/src/coverage/counters.rs
+++ b/compiler/rustc_mir_transform/src/coverage/counters.rs
@@ -14,6 +14,48 @@ use rustc_index::bit_set::BitSet;
 use rustc_index::IndexVec;
 use rustc_middle::mir::coverage::*;
 
+use std::fmt::{self, Debug};
+
+/// The coverage counter or counter expression associated with a particular
+/// BCB node or BCB edge.
+#[derive(Clone)]
+pub(super) enum BcbCounter {
+    Counter { function_source_hash: u64, id: CounterId },
+    Expression { id: ExpressionId, lhs: Operand, op: Op, rhs: Operand },
+}
+
+impl BcbCounter {
+    fn is_expression(&self) -> bool {
+        matches!(self, Self::Expression { .. })
+    }
+
+    pub(super) fn as_operand(&self) -> Operand {
+        match *self {
+            BcbCounter::Counter { id, .. } => Operand::Counter(id),
+            BcbCounter::Expression { id, .. } => Operand::Expression(id),
+        }
+    }
+}
+
+impl Debug for BcbCounter {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Counter { id, .. } => write!(fmt, "Counter({:?})", id.index()),
+            Self::Expression { id, lhs, op, rhs } => write!(
+                fmt,
+                "Expression({:?}) = {:?} {} {:?}",
+                id.index(),
+                lhs,
+                match op {
+                    Op::Add => "+",
+                    Op::Subtract => "-",
+                },
+                rhs,
+            ),
+        }
+    }
+}
+
 /// Generates and stores coverage counter and coverage expression information
 /// associated with nodes/edges in the BCB graph.
 pub(super) struct CoverageCounters {
@@ -22,18 +64,18 @@ pub(super) struct CoverageCounters {
     next_expression_id: ExpressionId,
 
     /// Coverage counters/expressions that are associated with individual BCBs.
-    bcb_counters: IndexVec<BasicCoverageBlock, Option<CoverageKind>>,
+    bcb_counters: IndexVec<BasicCoverageBlock, Option<BcbCounter>>,
     /// Coverage counters/expressions that are associated with the control-flow
     /// edge between two BCBs.
-    bcb_edge_counters: FxHashMap<(BasicCoverageBlock, BasicCoverageBlock), CoverageKind>,
+    bcb_edge_counters: FxHashMap<(BasicCoverageBlock, BasicCoverageBlock), BcbCounter>,
     /// Tracks which BCBs have a counter associated with some incoming edge.
     /// Only used by debug assertions, to verify that BCBs with incoming edge
     /// counters do not have their own physical counters (expressions are allowed).
     bcb_has_incoming_edge_counters: BitSet<BasicCoverageBlock>,
     /// Expression nodes that are not directly associated with any particular
     /// BCB/edge, but are needed as operands to more complex expressions.
-    /// These are always `CoverageKind::Expression`.
-    pub(super) intermediate_expressions: Vec<CoverageKind>,
+    /// These are always [`BcbCounter::Expression`].
+    pub(super) intermediate_expressions: Vec<BcbCounter>,
 
     pub debug_counters: DebugCounters,
 }
@@ -57,12 +99,12 @@ impl CoverageCounters {
     }
 
     /// Activate the `DebugCounters` data structures, to provide additional debug formatting
-    /// features when formatting `CoverageKind` (counter) values.
+    /// features when formatting [`BcbCounter`] (counter) values.
     pub fn enable_debug(&mut self) {
         self.debug_counters.enable();
     }
 
-    /// Makes `CoverageKind` `Counter`s and `Expressions` for the `BasicCoverageBlock`s directly or
+    /// Makes [`BcbCounter`] `Counter`s and `Expressions` for the `BasicCoverageBlock`s directly or
     /// indirectly associated with `CoverageSpans`, and accumulates additional `Expression`s
     /// representing intermediate values.
     pub fn make_bcb_counters(
@@ -73,11 +115,11 @@ impl CoverageCounters {
         MakeBcbCounters::new(self, basic_coverage_blocks).make_bcb_counters(coverage_spans)
     }
 
-    fn make_counter<F>(&mut self, debug_block_label_fn: F) -> CoverageKind
+    fn make_counter<F>(&mut self, debug_block_label_fn: F) -> BcbCounter
     where
         F: Fn() -> Option<String>,
     {
-        let counter = CoverageKind::Counter {
+        let counter = BcbCounter::Counter {
             function_source_hash: self.function_source_hash,
             id: self.next_counter(),
         };
@@ -93,19 +135,19 @@ impl CoverageCounters {
         op: Op,
         rhs: Operand,
         debug_block_label_fn: F,
-    ) -> CoverageKind
+    ) -> BcbCounter
     where
         F: Fn() -> Option<String>,
     {
         let id = self.next_expression();
-        let expression = CoverageKind::Expression { id, lhs, op, rhs };
+        let expression = BcbCounter::Expression { id, lhs, op, rhs };
         if self.debug_counters.is_enabled() {
             self.debug_counters.add_counter(&expression, (debug_block_label_fn)());
         }
         expression
     }
 
-    pub fn make_identity_counter(&mut self, counter_operand: Operand) -> CoverageKind {
+    pub fn make_identity_counter(&mut self, counter_operand: Operand) -> BcbCounter {
         let some_debug_block_label = if self.debug_counters.is_enabled() {
             self.debug_counters.some_block_label(counter_operand).cloned()
         } else {
@@ -134,7 +176,7 @@ impl CoverageCounters {
     fn set_bcb_counter(
         &mut self,
         bcb: BasicCoverageBlock,
-        counter_kind: CoverageKind,
+        counter_kind: BcbCounter,
     ) -> Result<Operand, Error> {
         debug_assert!(
             // If the BCB has an edge counter (to be injected into a new `BasicBlock`), it can also
@@ -158,7 +200,7 @@ impl CoverageCounters {
         &mut self,
         from_bcb: BasicCoverageBlock,
         to_bcb: BasicCoverageBlock,
-        counter_kind: CoverageKind,
+        counter_kind: BcbCounter,
     ) -> Result<Operand, Error> {
         if level_enabled!(tracing::Level::DEBUG) {
             // If the BCB has an edge counter (to be injected into a new `BasicBlock`), it can also
@@ -183,17 +225,17 @@ impl CoverageCounters {
         }
     }
 
-    pub(super) fn bcb_counter(&self, bcb: BasicCoverageBlock) -> Option<&CoverageKind> {
+    pub(super) fn bcb_counter(&self, bcb: BasicCoverageBlock) -> Option<&BcbCounter> {
         self.bcb_counters[bcb].as_ref()
     }
 
-    pub(super) fn take_bcb_counter(&mut self, bcb: BasicCoverageBlock) -> Option<CoverageKind> {
+    pub(super) fn take_bcb_counter(&mut self, bcb: BasicCoverageBlock) -> Option<BcbCounter> {
         self.bcb_counters[bcb].take()
     }
 
     pub(super) fn drain_bcb_counters(
         &mut self,
-    ) -> impl Iterator<Item = (BasicCoverageBlock, CoverageKind)> + '_ {
+    ) -> impl Iterator<Item = (BasicCoverageBlock, BcbCounter)> + '_ {
         self.bcb_counters
             .iter_enumerated_mut()
             .filter_map(|(bcb, counter)| Some((bcb, counter.take()?)))
@@ -201,7 +243,7 @@ impl CoverageCounters {
 
     pub(super) fn drain_bcb_edge_counters(
         &mut self,
-    ) -> impl Iterator<Item = ((BasicCoverageBlock, BasicCoverageBlock), CoverageKind)> + '_ {
+    ) -> impl Iterator<Item = ((BasicCoverageBlock, BasicCoverageBlock), BcbCounter)> + '_ {
         self.bcb_edge_counters.drain()
     }
 }
@@ -653,7 +695,7 @@ impl<'a> MakeBcbCounters<'a> {
         self.branch_counter(branch).is_none()
     }
 
-    fn branch_counter(&self, branch: &BcbBranch) -> Option<&CoverageKind> {
+    fn branch_counter(&self, branch: &BcbBranch) -> Option<&BcbCounter> {
         let to_bcb = branch.target_bcb;
         if let Some(from_bcb) = branch.edge_from_bcb {
             self.coverage_counters.bcb_edge_counters.get(&(from_bcb, to_bcb))
@@ -675,7 +717,7 @@ impl<'a> MakeBcbCounters<'a> {
     }
 
     #[inline]
-    fn format_counter(&self, counter_kind: &CoverageKind) -> String {
+    fn format_counter(&self, counter_kind: &BcbCounter) -> String {
         self.coverage_counters.debug_counters.format_counter(counter_kind)
     }
 }
diff --git a/compiler/rustc_mir_transform/src/coverage/debug.rs b/compiler/rustc_mir_transform/src/coverage/debug.rs
index 083f1f8aef6..af616c498fd 100644
--- a/compiler/rustc_mir_transform/src/coverage/debug.rs
+++ b/compiler/rustc_mir_transform/src/coverage/debug.rs
@@ -108,7 +108,7 @@
 //!         recursively, generating labels with nested operations, enclosed in parentheses
 //!         (for example: `bcb2 + (bcb0 - bcb1)`).
 
-use super::counters::CoverageCounters;
+use super::counters::{BcbCounter, CoverageCounters};
 use super::graph::{BasicCoverageBlock, BasicCoverageBlockData, CoverageGraph};
 use super::spans::CoverageSpan;
 
@@ -247,11 +247,11 @@ impl Default for ExpressionFormat {
     }
 }
 
-/// If enabled, this struct maintains a map from `CoverageKind` IDs (as `Operand`) to
-/// the `CoverageKind` data and optional label (normally, the counter's associated
+/// If enabled, this struct maintains a map from `BcbCounter` IDs (as `Operand`) to
+/// the `BcbCounter` data and optional label (normally, the counter's associated
 /// `BasicCoverageBlock` format string, if any).
 ///
-/// Use `format_counter` to convert one of these `CoverageKind` counters to a debug output string,
+/// Use `format_counter` to convert one of these `BcbCounter` counters to a debug output string,
 /// as directed by the `DebugOptions`. This allows the format of counter labels in logs and dump
 /// files (including the `CoverageGraph` graphviz file) to be changed at runtime, via environment
 /// variable.
@@ -276,7 +276,7 @@ impl DebugCounters {
         self.some_counters.is_some()
     }
 
-    pub fn add_counter(&mut self, counter_kind: &CoverageKind, some_block_label: Option<String>) {
+    pub fn add_counter(&mut self, counter_kind: &BcbCounter, some_block_label: Option<String>) {
         if let Some(counters) = &mut self.some_counters {
             let id = counter_kind.as_operand();
             counters
@@ -291,21 +291,20 @@ impl DebugCounters {
         })
     }
 
-    pub fn format_counter(&self, counter_kind: &CoverageKind) -> String {
+    pub fn format_counter(&self, counter_kind: &BcbCounter) -> String {
         match *counter_kind {
-            CoverageKind::Counter { .. } => {
+            BcbCounter::Counter { .. } => {
                 format!("Counter({})", self.format_counter_kind(counter_kind))
             }
-            CoverageKind::Expression { .. } => {
+            BcbCounter::Expression { .. } => {
                 format!("Expression({})", self.format_counter_kind(counter_kind))
             }
-            CoverageKind::Unreachable { .. } => "Unreachable".to_owned(),
         }
     }
 
-    fn format_counter_kind(&self, counter_kind: &CoverageKind) -> String {
+    fn format_counter_kind(&self, counter_kind: &BcbCounter) -> String {
         let counter_format = &debug_options().counter_format;
-        if let CoverageKind::Expression { id, lhs, op, rhs } = *counter_kind {
+        if let BcbCounter::Expression { id, lhs, op, rhs } = *counter_kind {
             if counter_format.operation {
                 return format!(
                     "{}{} {} {}",
@@ -346,7 +345,7 @@ impl DebugCounters {
         }
         if let Some(counters) = &self.some_counters {
             if let Some(DebugCounter { counter_kind, some_block_label }) = counters.get(&operand) {
-                if let CoverageKind::Expression { .. } = counter_kind {
+                if let BcbCounter::Expression { .. } = counter_kind {
                     if let Some(label) = some_block_label && debug_options().counter_format.block {
                         return format!(
                             "{}:({})",
@@ -366,12 +365,12 @@ impl DebugCounters {
 /// A non-public support class to `DebugCounters`.
 #[derive(Debug)]
 struct DebugCounter {
-    counter_kind: CoverageKind,
+    counter_kind: BcbCounter,
     some_block_label: Option<String>,
 }
 
 impl DebugCounter {
-    fn new(counter_kind: CoverageKind, some_block_label: Option<String>) -> Self {
+    fn new(counter_kind: BcbCounter, some_block_label: Option<String>) -> Self {
         Self { counter_kind, some_block_label }
     }
 }
@@ -380,9 +379,9 @@ impl DebugCounter {
 /// a Graphviz (.dot file) representation of the `CoverageGraph`, for debugging purposes.
 pub(super) struct GraphvizData {
     some_bcb_to_coverage_spans_with_counters:
-        Option<FxHashMap<BasicCoverageBlock, Vec<(CoverageSpan, CoverageKind)>>>,
-    some_bcb_to_dependency_counters: Option<FxHashMap<BasicCoverageBlock, Vec<CoverageKind>>>,
-    some_edge_to_counter: Option<FxHashMap<(BasicCoverageBlock, BasicBlock), CoverageKind>>,
+        Option<FxHashMap<BasicCoverageBlock, Vec<(CoverageSpan, BcbCounter)>>>,
+    some_bcb_to_dependency_counters: Option<FxHashMap<BasicCoverageBlock, Vec<BcbCounter>>>,
+    some_edge_to_counter: Option<FxHashMap<(BasicCoverageBlock, BasicBlock), BcbCounter>>,
 }
 
 impl GraphvizData {
@@ -409,7 +408,7 @@ impl GraphvizData {
         &mut self,
         bcb: BasicCoverageBlock,
         coverage_span: &CoverageSpan,
-        counter_kind: &CoverageKind,
+        counter_kind: &BcbCounter,
     ) {
         if let Some(bcb_to_coverage_spans_with_counters) =
             self.some_bcb_to_coverage_spans_with_counters.as_mut()
@@ -424,7 +423,7 @@ impl GraphvizData {
     pub fn get_bcb_coverage_spans_with_counters(
         &self,
         bcb: BasicCoverageBlock,
-    ) -> Option<&[(CoverageSpan, CoverageKind)]> {
+    ) -> Option<&[(CoverageSpan, BcbCounter)]> {
         if let Some(bcb_to_coverage_spans_with_counters) =
             self.some_bcb_to_coverage_spans_with_counters.as_ref()
         {
@@ -437,7 +436,7 @@ impl GraphvizData {
     pub fn add_bcb_dependency_counter(
         &mut self,
         bcb: BasicCoverageBlock,
-        counter_kind: &CoverageKind,
+        counter_kind: &BcbCounter,
     ) {
         if let Some(bcb_to_dependency_counters) = self.some_bcb_to_dependency_counters.as_mut() {
             bcb_to_dependency_counters
@@ -447,7 +446,7 @@ impl GraphvizData {
         }
     }
 
-    pub fn get_bcb_dependency_counters(&self, bcb: BasicCoverageBlock) -> Option<&[CoverageKind]> {
+    pub fn get_bcb_dependency_counters(&self, bcb: BasicCoverageBlock) -> Option<&[BcbCounter]> {
         if let Some(bcb_to_dependency_counters) = self.some_bcb_to_dependency_counters.as_ref() {
             bcb_to_dependency_counters.get(&bcb).map(Deref::deref)
         } else {
@@ -459,7 +458,7 @@ impl GraphvizData {
         &mut self,
         from_bcb: BasicCoverageBlock,
         to_bb: BasicBlock,
-        counter_kind: &CoverageKind,
+        counter_kind: &BcbCounter,
     ) {
         if let Some(edge_to_counter) = self.some_edge_to_counter.as_mut() {
             edge_to_counter
@@ -472,7 +471,7 @@ impl GraphvizData {
         &self,
         from_bcb: BasicCoverageBlock,
         to_bb: BasicBlock,
-    ) -> Option<&CoverageKind> {
+    ) -> Option<&BcbCounter> {
         if let Some(edge_to_counter) = self.some_edge_to_counter.as_ref() {
             edge_to_counter.get(&(from_bcb, to_bb))
         } else {
@@ -488,7 +487,7 @@ impl GraphvizData {
 pub(super) struct UsedExpressions {
     some_used_expression_operands: Option<FxHashMap<Operand, Vec<ExpressionId>>>,
     some_unused_expressions:
-        Option<Vec<(CoverageKind, Option<BasicCoverageBlock>, BasicCoverageBlock)>>,
+        Option<Vec<(BcbCounter, Option<BasicCoverageBlock>, BasicCoverageBlock)>>,
 }
 
 impl UsedExpressions {
@@ -506,16 +505,16 @@ impl UsedExpressions {
         self.some_used_expression_operands.is_some()
     }
 
-    pub fn add_expression_operands(&mut self, expression: &CoverageKind) {
+    pub fn add_expression_operands(&mut self, expression: &BcbCounter) {
         if let Some(used_expression_operands) = self.some_used_expression_operands.as_mut() {
-            if let CoverageKind::Expression { id, lhs, rhs, .. } = *expression {
+            if let BcbCounter::Expression { id, lhs, rhs, .. } = *expression {
                 used_expression_operands.entry(lhs).or_insert_with(Vec::new).push(id);
                 used_expression_operands.entry(rhs).or_insert_with(Vec::new).push(id);
             }
         }
     }
 
-    pub fn expression_is_used(&self, expression: &CoverageKind) -> bool {
+    pub fn expression_is_used(&self, expression: &BcbCounter) -> bool {
         if let Some(used_expression_operands) = self.some_used_expression_operands.as_ref() {
             used_expression_operands.contains_key(&expression.as_operand())
         } else {
@@ -525,7 +524,7 @@ impl UsedExpressions {
 
     pub fn add_unused_expression_if_not_found(
         &mut self,
-        expression: &CoverageKind,
+        expression: &BcbCounter,
         edge_from_bcb: Option<BasicCoverageBlock>,
         target_bcb: BasicCoverageBlock,
     ) {
@@ -540,11 +539,11 @@ impl UsedExpressions {
         }
     }
 
-    /// Return the list of unused counters (if any) as a tuple with the counter (`CoverageKind`),
+    /// Return the list of unused counters (if any) as a tuple with the counter (`BcbCounter`),
     /// optional `from_bcb` (if it was an edge counter), and `target_bcb`.
     pub fn get_unused_expressions(
         &self,
-    ) -> Vec<(CoverageKind, Option<BasicCoverageBlock>, BasicCoverageBlock)> {
+    ) -> Vec<(BcbCounter, Option<BasicCoverageBlock>, BasicCoverageBlock)> {
         if let Some(unused_expressions) = self.some_unused_expressions.as_ref() {
             unused_expressions.clone()
         } else {
@@ -560,7 +559,7 @@ impl UsedExpressions {
         bcb_counters_without_direct_coverage_spans: &[(
             Option<BasicCoverageBlock>,
             BasicCoverageBlock,
-            CoverageKind,
+            BcbCounter,
         )],
     ) {
         if self.is_enabled() {
@@ -662,7 +661,7 @@ pub(super) fn dump_coverage_graphviz<'tcx>(
     basic_coverage_blocks: &CoverageGraph,
     coverage_counters: &CoverageCounters,
     graphviz_data: &GraphvizData,
-    intermediate_expressions: &[CoverageKind],
+    intermediate_expressions: &[BcbCounter],
     debug_used_expressions: &UsedExpressions,
 ) {
     let debug_counters = &coverage_counters.debug_counters;
@@ -743,9 +742,9 @@ fn bcb_to_string_sections<'tcx>(
     coverage_counters: &CoverageCounters,
     bcb: BasicCoverageBlock,
     bcb_data: &BasicCoverageBlockData,
-    some_coverage_spans_with_counters: Option<&[(CoverageSpan, CoverageKind)]>,
-    some_dependency_counters: Option<&[CoverageKind]>,
-    some_intermediate_expressions: Option<&[CoverageKind]>,
+    some_coverage_spans_with_counters: Option<&[(CoverageSpan, BcbCounter)]>,
+    some_dependency_counters: Option<&[BcbCounter]>,
+    some_intermediate_expressions: Option<&[BcbCounter]>,
 ) -> Vec<String> {
     let debug_counters = &coverage_counters.debug_counters;
 
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 43a54496db0..39b56d1f00b 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -8,9 +8,9 @@ mod spans;
 #[cfg(test)]
 mod tests;
 
-use counters::CoverageCounters;
-use graph::{BasicCoverageBlock, BasicCoverageBlockData, CoverageGraph};
-use spans::{CoverageSpan, CoverageSpans};
+use self::counters::{BcbCounter, CoverageCounters};
+use self::graph::{BasicCoverageBlock, BasicCoverageBlockData, CoverageGraph};
+use self::spans::{CoverageSpan, CoverageSpans};
 
 use crate::MirPass;
 
@@ -270,8 +270,11 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
 
         ////////////////////////////////////////////////////
         // Finally, inject the intermediate expressions collected along the way.
-        for intermediate_expression in self.coverage_counters.intermediate_expressions.drain(..) {
-            inject_intermediate_expression(self.mir_body, intermediate_expression);
+        for intermediate_expression in &self.coverage_counters.intermediate_expressions {
+            inject_intermediate_expression(
+                self.mir_body,
+                self.make_mir_coverage_kind(intermediate_expression),
+            );
         }
     }
 
@@ -314,7 +317,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
 
             inject_statement(
                 self.mir_body,
-                counter_kind,
+                self.make_mir_coverage_kind(&counter_kind),
                 self.bcb_leader_bb(bcb),
                 Some(code_region),
             );
@@ -362,7 +365,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
             );
 
             match counter_kind {
-                CoverageKind::Counter { .. } => {
+                BcbCounter::Counter { .. } => {
                     let inject_to_bb = if let Some(from_bcb) = edge_from_bcb {
                         // The MIR edge starts `from_bb` (the outgoing / last BasicBlock in
                         // `from_bcb`) and ends at `to_bb` (the incoming / first BasicBlock in the
@@ -395,12 +398,17 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
                         target_bb
                     };
 
-                    inject_statement(self.mir_body, counter_kind, inject_to_bb, None);
+                    inject_statement(
+                        self.mir_body,
+                        self.make_mir_coverage_kind(&counter_kind),
+                        inject_to_bb,
+                        None,
+                    );
                 }
-                CoverageKind::Expression { .. } => {
-                    inject_intermediate_expression(self.mir_body, counter_kind)
-                }
-                _ => bug!("CoverageKind should be a counter"),
+                BcbCounter::Expression { .. } => inject_intermediate_expression(
+                    self.mir_body,
+                    self.make_mir_coverage_kind(&counter_kind),
+                ),
             }
         }
     }
@@ -421,9 +429,20 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
     }
 
     #[inline]
-    fn format_counter(&self, counter_kind: &CoverageKind) -> String {
+    fn format_counter(&self, counter_kind: &BcbCounter) -> String {
         self.coverage_counters.debug_counters.format_counter(counter_kind)
     }
+
+    fn make_mir_coverage_kind(&self, counter_kind: &BcbCounter) -> CoverageKind {
+        match *counter_kind {
+            BcbCounter::Counter { function_source_hash, id } => {
+                CoverageKind::Counter { function_source_hash, id }
+            }
+            BcbCounter::Expression { id, lhs, op, rhs } => {
+                CoverageKind::Expression { id, lhs, op, rhs }
+            }
+        }
+    }
 }
 
 fn inject_edge_counter_basic_block(
diff --git a/compiler/rustc_mir_transform/src/coverage/tests.rs b/compiler/rustc_mir_transform/src/coverage/tests.rs
index f46542ef58b..99ac769be64 100644
--- a/compiler/rustc_mir_transform/src/coverage/tests.rs
+++ b/compiler/rustc_mir_transform/src/coverage/tests.rs
@@ -34,7 +34,6 @@ use itertools::Itertools;
 use rustc_data_structures::graph::WithNumNodes;
 use rustc_data_structures::graph::WithSuccessors;
 use rustc_index::{Idx, IndexVec};
-use rustc_middle::mir::coverage::CoverageKind;
 use rustc_middle::mir::*;
 use rustc_middle::ty;
 use rustc_span::{self, BytePos, Pos, Span, DUMMY_SP};
@@ -685,7 +684,7 @@ fn test_make_bcb_counters() {
         assert_eq!(
             0, // bcb1 has a `Counter` with id = 0
             match coverage_counters.bcb_counter(bcb1).expect("should have a counter") {
-                CoverageKind::Counter { id, .. } => id,
+                counters::BcbCounter::Counter { id, .. } => id,
                 _ => panic!("expected a Counter"),
             }
             .as_u32()
@@ -695,7 +694,7 @@ fn test_make_bcb_counters() {
         assert_eq!(
             1, // bcb2 has a `Counter` with id = 1
             match coverage_counters.bcb_counter(bcb2).expect("should have a counter") {
-                CoverageKind::Counter { id, .. } => id,
+                counters::BcbCounter::Counter { id, .. } => id,
                 _ => panic!("expected a Counter"),
             }
             .as_u32()