coverage. Refactor MCDCInfoBuilder for pattern matching implementation

Author: zhuyunxing

compiler/rustc_middle/src/mir/coverage.rs

@@ -51,6 +51,14 @@ rustc_index::newtype_index! {
     pub struct ExpressionId {}
 }
 
+rustc_index::newtype_index! {
+    /// ID of a mcdc decision. Used to identify decision in a function.
+    #[derive(HashStable)]
+    #[encodable]
+    #[debug_format = "DecisionId({})"]
+    pub struct DecisionId {}
+}
+
 rustc_index::newtype_index! {
     /// ID of a mcdc condition. Used by llvm to check mcdc coverage.
     ///

compiler/rustc_mir_build/src/build/coverageinfo.rs

@@ -129,10 +129,10 @@ impl BranchInfoBuilder {
         // Separate path for handling branches when MC/DC is enabled.
         if let Some(mcdc_info) = self.mcdc_info.as_mut() {
             let inject_block_marker =
-                |source_info, block| self.markers.inject_block_marker(cfg, source_info, block);
+                |block| self.markers.inject_block_marker(cfg, source_info, block);
             mcdc_info.visit_evaluated_condition(
                 tcx,
-                source_info,
+                source_info.span,
                 true_block,
                 false_block,
                 inject_block_marker,
@@ -162,9 +162,13 @@ impl BranchInfoBuilder {
             return None;
         }
 
-        let (mcdc_decision_spans, mcdc_branch_spans) =
+        let (mut mcdc_branch_spans, mcdc_spans) =
             mcdc_info.map(MCDCInfoBuilder::into_done).unwrap_or_default();
-
+        let mut mcdc_decision_spans = Vec::with_capacity(mcdc_spans.len());
+        for (decision, conditions) in mcdc_spans {
+            mcdc_branch_spans.extend(conditions);
+            mcdc_decision_spans.push(decision);
+        }
         Some(Box::new(mir::coverage::BranchInfo {
             num_block_markers,
             branch_spans,