Working branch-level code coverage

Cargo.lock

@@ -2938,8 +2938,9 @@ dependencies = [
 
 [[package]]
 name = "rust-demangler"
-version = "0.0.0"
+version = "0.0.1"
 dependencies = [
+ "regex",
  "rustc-demangle",
 ]
 

compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs

@@ -126,6 +126,7 @@ impl CoverageMapGenerator {
                 let (filenames_index, _) = self.filenames.insert_full(c_filename);
                 virtual_file_mapping.push(filenames_index as u32);
             }
+            debug!("Adding counter {:?} to map for {:?}", counter, region,);
             mapping_regions.push(CounterMappingRegion::code_region(
                 counter,
                 current_file_id,

compiler/rustc_codegen_ssa/src/coverageinfo/map.rs

@@ -143,7 +143,9 @@ impl FunctionCoverage {
         let id_to_counter =
             |new_indexes: &IndexVec<InjectedExpressionIndex, MappedExpressionIndex>,
              id: ExpressionOperandId| {
-                if id.index() < self.counters.len() {
+                if id == ExpressionOperandId::ZERO {
+                    Some(Counter::zero())
+                } else if id.index() < self.counters.len() {
                     let index = CounterValueReference::from(id.index());
                     self.counters
                         .get(index)
@@ -179,14 +181,19 @@ impl FunctionCoverage {
                 // been assigned a `new_index`.
                 let mapped_expression_index =
                     MappedExpressionIndex::from(counter_expressions.len());
-                counter_expressions.push(CounterExpression::new(
+                let expression = CounterExpression::new(
                     lhs_counter,
                     match op {
                         Op::Add => ExprKind::Add,
                         Op::Subtract => ExprKind::Subtract,
                     },
                     rhs_counter,
-                ));
+                );
+                debug!(
+                    "Adding expression {:?} = {:?} at {:?}",
+                    mapped_expression_index, expression, region
+                );
+                counter_expressions.push(expression);
                 new_indexes[original_index] = mapped_expression_index;
                 expression_regions.push((Counter::expression(mapped_expression_index), region));
             }

compiler/rustc_data_structures/src/graph/dominators/mod.rs

@@ -9,6 +9,7 @@ use super::iterate::reverse_post_order;
 use super::ControlFlowGraph;
 use rustc_index::vec::{Idx, IndexVec};
 use std::borrow::BorrowMut;
+use std::cmp::Ordering;
 
 #[cfg(test)]
 mod tests;
@@ -108,6 +109,14 @@ impl<Node: Idx> Dominators<Node> {
         // FIXME -- could be optimized by using post-order-rank
         self.dominators(node).any(|n| n == dom)
     }
+
+    /// Provide deterministic ordering of nodes such that, if any two nodes have a dominator
+    /// relationship, the dominator will always precede the dominated. (The relative ordering
+    /// of two unrelated nodes will also be consistent, but otherwise the order has no
+    /// meaning.) This method cannot be used to determine if either Node dominates the other.
+    pub fn rank_partial_cmp(&self, lhs: Node, rhs: Node) -> Option<Ordering> {
+        self.post_order_rank[lhs].partial_cmp(&self.post_order_rank[rhs])
+    }
 }
 
 pub struct Iter<'dom, Node: Idx> {

compiler/rustc_middle/src/mir/coverage/mod.rs

@@ -14,6 +14,20 @@ rustc_index::newtype_index! {
     }
 }
 
+impl ExpressionOperandId {
+    /// An expression operand for a "zero counter", as described in the following references:
+    ///
+    /// * https://github.com/rust-lang/llvm-project/blob/llvmorg-8.0.0/llvm/docs/CoverageMappingFormat.rst#counter
+    /// * https://github.com/rust-lang/llvm-project/blob/llvmorg-8.0.0/llvm/docs/CoverageMappingFormat.rst#tag
+    /// * https://github.com/rust-lang/llvm-project/blob/llvmorg-8.0.0/llvm/docs/CoverageMappingFormat.rst#counter-expressions
+    ///
+    /// This operand can be used to count two or more separate code regions with a single counter,
+    /// if they run sequentially with no branches, by injecting the `Counter` in a `BasicBlock` for
+    /// one of the code regions, and inserting `CounterExpression`s ("add ZERO to the counter") in
+    /// the coverage map for the other code regions.
+    pub const ZERO: Self = Self::from_u32(0);
+}
+
 rustc_index::newtype_index! {
     pub struct CounterValueReference {
         derive [HashStable]
@@ -22,6 +36,11 @@ rustc_index::newtype_index! {
     }
 }
 
+impl CounterValueReference {
+    // Counters start at 1 to reserve 0 for ExpressionOperandId::ZERO.
+    pub const START: Self = Self::from_u32(1);
+}
+
 rustc_index::newtype_index! {
     pub struct InjectedExpressionIndex {
         derive [HashStable]

compiler/rustc_middle/src/mir/visit.rs

@@ -752,7 +752,7 @@ macro_rules! make_mir_visitor {
             }
 
             fn super_coverage(&mut self,
-                              _kind: & $($mutability)? Coverage,
+                              _coverage: & $($mutability)? Coverage,
                               _location: Location) {
             }