coverage. Generate Mappings of decisions and conditions for MC/DC

1 files changed, 29 insertions, 5 deletions

diff --git a/compiler/rustc_mir_transform/src/coverage/spans.rs b/compiler/rustc_mir_transform/src/coverage/spans.rs
index 03ede886688..a4cd8a38c66 100644
--- a/compiler/rustc_mir_transform/src/coverage/spans.rs
+++ b/compiler/rustc_mir_transform/src/coverage/spans.rs
@@ -1,7 +1,9 @@
 use rustc_data_structures::graph::DirectedGraph;
 use rustc_index::bit_set::BitSet;
 use rustc_middle::mir;
+use rustc_middle::mir::coverage::ConditionInfo;
 use rustc_span::{BytePos, Span};
+use std::collections::BTreeSet;
 
 use crate::coverage::graph::{BasicCoverageBlock, CoverageGraph, START_BCB};
 use crate::coverage::spans::from_mir::SpanFromMir;
@@ -9,12 +11,20 @@ use crate::coverage::ExtractedHirInfo;
 
 mod from_mir;
 
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Debug)]
 pub(super) enum BcbMappingKind {
     /// Associates an ordinary executable code span with its corresponding BCB.
     Code(BasicCoverageBlock),
     /// Associates a branch span with BCBs for its true and false arms.
     Branch { true_bcb: BasicCoverageBlock, false_bcb: BasicCoverageBlock },
+    /// Associates a mcdc branch span with condition info besides fields for normal branch.
+    MCDCBranch {
+        true_bcb: BasicCoverageBlock,
+        false_bcb: BasicCoverageBlock,
+        condition_info: ConditionInfo,
+    },
+    /// Associates a mcdc decision with its join BCB.
+    MCDCDecision { end_bcbs: BTreeSet<BasicCoverageBlock>, bitmap_idx: u32, conditions_num: u16 },
 }
 
 #[derive(Debug)]
@@ -26,6 +36,7 @@ pub(super) struct BcbMapping {
 pub(super) struct CoverageSpans {
     bcb_has_mappings: BitSet<BasicCoverageBlock>,
     mappings: Vec<BcbMapping>,
+    test_vector_bitmap_bytes: u32,
 }
 
 impl CoverageSpans {
@@ -36,6 +47,10 @@ impl CoverageSpans {
     pub(super) fn all_bcb_mappings(&self) -> impl Iterator<Item = &BcbMapping> {
         self.mappings.iter()
     }
+
+    pub(super) fn test_vector_bitmap_bytes(&self) -> u32 {
+        self.test_vector_bitmap_bytes
+    }
 }
 
 /// Extracts coverage-relevant spans from MIR, and associates them with
@@ -85,17 +100,26 @@ pub(super) fn generate_coverage_spans(
     let mut insert = |bcb| {
         bcb_has_mappings.insert(bcb);
     };
-    for &BcbMapping { kind, span: _ } in &mappings {
-        match kind {
+    let mut test_vector_bitmap_bytes = 0;
+    for BcbMapping { kind, span: _ } in &mappings {
+        match *kind {
             BcbMappingKind::Code(bcb) => insert(bcb),
-            BcbMappingKind::Branch { true_bcb, false_bcb } => {
+            BcbMappingKind::Branch { true_bcb, false_bcb }
+            | BcbMappingKind::MCDCBranch { true_bcb, false_bcb, .. } => {
                 insert(true_bcb);
                 insert(false_bcb);
             }
+            BcbMappingKind::MCDCDecision { bitmap_idx, conditions_num, .. } => {
+                // `bcb_has_mappings` is used for inject coverage counters
+                // but they are not needed for decision BCBs.
+                // While the length of test vector bitmap should be calculated here.
+                test_vector_bitmap_bytes = test_vector_bitmap_bytes
+                    .max(bitmap_idx + (1_u32 << conditions_num as u32).div_ceil(8));
+            }
         }
     }
 
-    Some(CoverageSpans { bcb_has_mappings, mappings })
+    Some(CoverageSpans { bcb_has_mappings, mappings, test_vector_bitmap_bytes })
 }
 
 #[derive(Debug)]