coverage. Implement branch coverage in mcdc for pattern match

Author: zhuyunxing

compiler/rustc_middle/src/mir/coverage.rs

@@ -280,8 +280,7 @@ pub struct BranchInfo {
     /// 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>,
+    pub mcdc_info: Option<MCDCBranchInfo>,
 }
 
 #[derive(Clone, Debug)]
@@ -321,6 +320,20 @@ pub struct MCDCBranchSpan {
     pub false_marker: BlockMarkerId,
 }
 
+#[derive(Clone, Debug)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+pub struct MCDCMatchArmSpan {
+    pub span: Span,
+    pub condition_info: Option<ConditionInfo>,
+    // Mark the blocks which test the pattern.
+    pub test_markers: Vec<BlockMarkerId>,
+    // The blocks switched into if this pattern was matched.
+    pub true_markers: Vec<BlockMarkerId>,
+    // The blocks of `true_markers` of the prior bindings.
+    // Eg. in `A | B` pattern A is prior to pattern B.
+    pub prior_binding_markers: Vec<BlockMarkerId>,
+}
+
 #[derive(Copy, Clone, Debug)]
 #[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
 pub struct DecisionInfo {
@@ -335,3 +348,20 @@ pub struct MCDCDecisionSpan {
     pub conditions_num: usize,
     pub end_markers: Vec<BlockMarkerId>,
 }
+
+/// Branch information recorded during THIR-to-MIR lowering, and stored in MIR.
+#[derive(Clone, Debug)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+pub struct MCDCBranchInfo {
+    pub branch_spans: Vec<MCDCBranchSpan>,
+    pub match_arm_spans: Vec<MCDCMatchArmSpan>,
+    pub decision_spans: Vec<MCDCDecisionSpan>,
+}
+
+impl MCDCBranchInfo {
+    pub fn calc_bitmap_bytes(&self) -> u32 {
+        self.decision_spans
+            .iter()
+            .fold(0, |acc, decision| acc + (1_u32 << decision.conditions_num).div_ceil(8))
+    }
+}

compiler/rustc_middle/src/mir/pretty.rs

@@ -475,35 +475,57 @@ fn write_coverage_branch_info(
     branch_info: &coverage::BranchInfo,
     w: &mut dyn io::Write,
 ) -> io::Result<()> {
-    let coverage::BranchInfo { branch_spans, mcdc_branch_spans, mcdc_decision_spans, .. } =
-        branch_info;
+    let coverage::BranchInfo { branch_spans, mcdc_info, .. } = branch_info;
 
+    let mut printed = false;
     for coverage::BranchSpan { span, true_marker, false_marker } in branch_spans {
         writeln!(
             w,
             "{INDENT}coverage branch {{ true: {true_marker:?}, false: {false_marker:?} }} => {span:?}",
         )?;
     }
 
-    for coverage::MCDCBranchSpan { span, condition_info, true_marker, false_marker } in
-        mcdc_branch_spans
+    printed |= !branch_spans.is_empty();
+
+    if let Some(coverage::MCDCBranchInfo { branch_spans, decision_spans, match_arm_spans }) =
+        mcdc_info.as_ref()
     {
-        writeln!(
-            w,
-            "{INDENT}coverage mcdc branch {{ condition_id: {:?}, true: {true_marker:?}, false: {false_marker:?} }} => {span:?}",
-            condition_info.map(|info| info.condition_id)
-        )?;
-    }
+        for coverage::MCDCBranchSpan { span, condition_info, true_marker, false_marker } in
+            branch_spans
+        {
+            writeln!(
+                w,
+                "{INDENT}coverage mcdc branch {{ condition_id: {:?}, true: {true_marker:?}, false: {false_marker:?} }} => {span:?}",
+                condition_info.map(|info| info.condition_id)
+            )?;
+        }
 
-    for coverage::MCDCDecisionSpan { span, conditions_num, end_markers } in mcdc_decision_spans {
-        writeln!(
-            w,
-            "{INDENT}coverage mcdc decision {{ conditions_num: {conditions_num:?}, end: {end_markers:?} }} => {span:?}"
-        )?;
+        for coverage::MCDCMatchArmSpan {
+            span,
+            condition_info,
+            test_markers,
+            true_markers,
+            prior_binding_markers,
+        } in match_arm_spans
+        {
+            writeln!(
+                w,
+                "{INDENT}coverage mcdc match arm {{ condition_id: {:?}, test: {test_markers:?}, true: {true_markers:?}, prior: {prior_binding_markers:?} }} => {span:?}",
+                condition_info.map(|info| info.condition_id)
+            )?;
+        }
+
+        for coverage::MCDCDecisionSpan { span, conditions_num, end_markers } in decision_spans {
+            writeln!(
+                w,
+                "{INDENT}coverage mcdc decision {{ conditions_num: {conditions_num:?}, end: {end_markers:?} }} => {span:?}"
+            )?;
+        }
+        printed |=
+            !branch_spans.is_empty() || !decision_spans.is_empty() || !match_arm_spans.is_empty();
     }
 
-    if !branch_spans.is_empty() || !mcdc_branch_spans.is_empty() || !mcdc_decision_spans.is_empty()
-    {
+    if printed {
         writeln!(w)?;
     }