2 files changed, 30 insertions, 31 deletions
diff --git a/compiler/rustc_middle/src/mir/coverage.rs b/compiler/rustc_middle/src/mir/coverage.rs
index 9a0f5a65321..4a876dc1228 100644
--- a/compiler/rustc_middle/src/mir/coverage.rs
+++ b/compiler/rustc_middle/src/mir/coverage.rs
@@ -128,8 +128,8 @@ pub enum CoverageKind {
 
     /// Marks the point in MIR control flow represented by a evaluated condition.
     ///
-    /// This is eventually lowered to `llvm.instrprof.mcdc.condbitmap.update` in LLVM IR.
-    CondBitmapUpdate { id: ConditionId, value: bool, decision_depth: u16 },
+    /// This is eventually lowered to instruments updating mcdc temp variables.
+    CondBitmapUpdate { index: u32, decision_depth: u16 },
 
     /// Marks the point in MIR control flow represented by a evaluated decision.
     ///
@@ -145,14 +145,8 @@ impl Debug for CoverageKind {
             BlockMarker { id } => write!(fmt, "BlockMarker({:?})", id.index()),
             CounterIncrement { id } => write!(fmt, "CounterIncrement({:?})", id.index()),
             ExpressionUsed { id } => write!(fmt, "ExpressionUsed({:?})", id.index()),
-            CondBitmapUpdate { id, value, decision_depth } => {
-                write!(
-                    fmt,
-                    "CondBitmapUpdate({:?}, {:?}, depth={:?})",
-                    id.index(),
-                    value,
-                    decision_depth
-                )
+            CondBitmapUpdate { index, decision_depth } => {
+                write!(fmt, "CondBitmapUpdate(index={:?}, depth={:?})", index, decision_depth)
             }
             TestVectorBitmapUpdate { bitmap_idx, decision_depth } => {
                 write!(fmt, "TestVectorUpdate({:?}, depth={:?})", bitmap_idx, decision_depth)
@@ -253,7 +247,7 @@ pub struct Mapping {
 pub struct FunctionCoverageInfo {
     pub function_source_hash: u64,
     pub num_counters: usize,
-    pub mcdc_bitmap_bytes: u32,
+    pub mcdc_bitmap_bits: usize,
     pub expressions: IndexVec<ExpressionId, Expression>,
     pub mappings: Vec<Mapping>,
     /// The depth of the deepest decision is used to know how many
@@ -275,8 +269,10 @@ pub struct CoverageInfoHi {
     /// data structures without having to scan the entire body first.
     pub num_block_markers: usize,
     pub branch_spans: Vec<BranchSpan>,
-    pub mcdc_branch_spans: Vec<MCDCBranchSpan>,
-    pub mcdc_decision_spans: Vec<MCDCDecisionSpan>,
+    /// Branch spans generated by mcdc. Because of some limits mcdc builder give up generating
+    /// decisions including them so that they are handled as normal branch spans.
+    pub mcdc_degraded_branch_spans: Vec<MCDCBranchSpan>,
+    pub mcdc_spans: Vec<(MCDCDecisionSpan, Vec<MCDCBranchSpan>)>,
 }
 
 #[derive(Clone, Debug)]
@@ -299,12 +295,9 @@ pub struct ConditionInfo {
 #[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
 pub struct MCDCBranchSpan {
     pub span: Span,
-    /// If `None`, this actually represents a normal branch span inserted for
-    /// code that was too complex for MC/DC.
-    pub condition_info: Option<ConditionInfo>,
+    pub condition_info: ConditionInfo,
     pub true_marker: BlockMarkerId,
     pub false_marker: BlockMarkerId,
-    pub decision_depth: u16,
 }
 
 #[derive(Copy, Clone, Debug)]
@@ -318,7 +311,7 @@ pub struct DecisionInfo {
 #[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
 pub struct MCDCDecisionSpan {
     pub span: Span,
-    pub num_conditions: usize,
     pub end_markers: Vec<BlockMarkerId>,
     pub decision_depth: u16,
+    pub num_conditions: usize,
 }
diff --git a/compiler/rustc_middle/src/mir/pretty.rs b/compiler/rustc_middle/src/mir/pretty.rs
index 9cafe804a8e..2a3a070a6e7 100644
--- a/compiler/rustc_middle/src/mir/pretty.rs
+++ b/compiler/rustc_middle/src/mir/pretty.rs
@@ -538,8 +538,8 @@ fn write_coverage_info_hi(
     let coverage::CoverageInfoHi {
         num_block_markers: _,
         branch_spans,
-        mcdc_branch_spans,
-        mcdc_decision_spans,
+        mcdc_degraded_branch_spans,
+        mcdc_spans,
     } = coverage_info_hi;
 
     // Only add an extra trailing newline if we printed at least one thing.
@@ -553,29 +553,35 @@ fn write_coverage_info_hi(
         did_print = true;
     }
 
-    for coverage::MCDCBranchSpan {
-        span,
-        condition_info,
-        true_marker,
-        false_marker,
-        decision_depth,
-    } in mcdc_branch_spans
+    for coverage::MCDCBranchSpan { span, true_marker, false_marker, .. } in
+        mcdc_degraded_branch_spans
     {
         writeln!(
             w,
-            "{INDENT}coverage mcdc branch {{ condition_id: {:?}, true: {true_marker:?}, false: {false_marker:?}, depth: {decision_depth:?} }} => {span:?}",
-            condition_info.map(|info| info.condition_id)
+            "{INDENT}coverage branch {{ true: {true_marker:?}, false: {false_marker:?} }} => {span:?}",
         )?;
         did_print = true;
     }
 
-    for coverage::MCDCDecisionSpan { span, num_conditions, end_markers, decision_depth } in
-        mcdc_decision_spans
+    for (
+        coverage::MCDCDecisionSpan { span, end_markers, decision_depth, num_conditions: _ },
+        conditions,
+    ) in mcdc_spans
     {
+        let num_conditions = conditions.len();
         writeln!(
             w,
             "{INDENT}coverage mcdc decision {{ num_conditions: {num_conditions:?}, end: {end_markers:?}, depth: {decision_depth:?} }} => {span:?}"
         )?;
+        for coverage::MCDCBranchSpan { span, condition_info, true_marker, false_marker } in
+            conditions
+        {
+            writeln!(
+                w,
+                "{INDENT}coverage mcdc branch {{ condition_id: {:?}, true: {true_marker:?}, false: {false_marker:?} }} => {span:?}",
+                condition_info.condition_id
+            )?;
+        }
         did_print = true;
     }