Rollup merge of #117651 - Zalathar:fold-sums, r=cjgillot

coverage: Simplify building coverage expressions based on sums

This is a combination of some interlinked changes to the code that creates coverage counters/expressions for nodes and edges in the coverage graph:

- Some preparatory cleanups in `MakeBcbCounters::make_branch_counters`
- Use `BcbCounter` (instead of `CovTerm`) when building coverage expressions
  - This makes it easier to introduce a fold for building sums
- Simplify the creation of coverage expressions based on sums, by having `Iterator::fold` do much of the work
- Get rid of the awkward `BcbBranch` enum, and replace it with graph edges represented as `(from_bcb, to_bcb)`
  - This further simplifies the body of the fold

Author: compiler-errors

compiler/rustc_mir_transform/src/coverage/counters.rs

@@ -62,6 +62,14 @@ impl CoverageGraph {
             Self { bcbs, bb_to_bcb, successors, predecessors, dominators: None };
         let dominators = dominators::dominators(&basic_coverage_blocks);
         basic_coverage_blocks.dominators = Some(dominators);
+
+        // The coverage graph's entry-point node (bcb0) always starts with bb0,
+        // which never has predecessors. Any other blocks merged into bcb0 can't
+        // have multiple (coverage-relevant) predecessors, so bcb0 always has
+        // zero in-edges.
+        assert!(basic_coverage_blocks[START_BCB].leader_bb() == mir::START_BLOCK);
+        assert!(basic_coverage_blocks.predecessors[START_BCB].is_empty());
+
         basic_coverage_blocks
     }
 
@@ -199,6 +207,25 @@ impl CoverageGraph {
     pub fn cmp_in_dominator_order(&self, a: BasicCoverageBlock, b: BasicCoverageBlock) -> Ordering {
         self.dominators.as_ref().unwrap().cmp_in_dominator_order(a, b)
     }
+
+    /// Returns true if the given node has 2 or more in-edges, i.e. 2 or more
+    /// predecessors.
+    ///
+    /// This property is interesting to code that assigns counters to nodes and
+    /// edges, because if a node _doesn't_ have multiple in-edges, then there's
+    /// no benefit in having a separate counter for its in-edge, because it
+    /// would have the same value as the node's own counter.
+    ///
+    /// FIXME: That assumption might not be true for [`TerminatorKind::Yield`]?
+    #[inline(always)]
+    pub(super) fn bcb_has_multiple_in_edges(&self, bcb: BasicCoverageBlock) -> bool {
+        // Even though bcb0 conceptually has an extra virtual in-edge due to
+        // being the entry point, we've already asserted that it has no _other_
+        // in-edges, so there's no possibility of it having _multiple_ in-edges.
+        // (And since its virtual in-edge doesn't exist in the graph, that edge
+        // can't have a separate counter anyway.)
+        self.predecessors[bcb].len() > 1
+    }
 }
 
 impl Index<BasicCoverageBlock> for CoverageGraph {
@@ -319,45 +346,6 @@ impl BasicCoverageBlockData {
     }
 }
 
-/// Represents a successor from a branching BasicCoverageBlock (such as the arms of a `SwitchInt`)
-/// as either the successor BCB itself, if it has only one incoming edge, or the successor _plus_
-/// the specific branching BCB, representing the edge between the two. The latter case
-/// distinguishes this incoming edge from other incoming edges to the same `target_bcb`.
-#[derive(Clone, Copy, PartialEq, Eq)]
-pub(super) struct BcbBranch {
-    pub edge_from_bcb: Option<BasicCoverageBlock>,
-    pub target_bcb: BasicCoverageBlock,
-}
-
-impl BcbBranch {
-    pub fn from_to(
-        from_bcb: BasicCoverageBlock,
-        to_bcb: BasicCoverageBlock,
-        basic_coverage_blocks: &CoverageGraph,
-    ) -> Self {
-        let edge_from_bcb = if basic_coverage_blocks.predecessors[to_bcb].len() > 1 {
-            Some(from_bcb)
-        } else {
-            None
-        };
-        Self { edge_from_bcb, target_bcb: to_bcb }
-    }
-
-    pub fn is_only_path_to_target(&self) -> bool {
-        self.edge_from_bcb.is_none()
-    }
-}
-
-impl std::fmt::Debug for BcbBranch {
-    fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        if let Some(from_bcb) = self.edge_from_bcb {
-            write!(fmt, "{:?}->{:?}", from_bcb, self.target_bcb)
-        } else {
-            write!(fmt, "{:?}", self.target_bcb)
-        }
-    }
-}
-
 // Returns the subset of a block's successors that are relevant to the coverage
 // graph, i.e. those that do not represent unwinds or unreachable branches.
 // FIXME(#78544): MIR InstrumentCoverage: Improve coverage of `#[should_panic]` tests and

compiler/rustc_mir_transform/src/coverage/graph.rs

@@ -197,12 +197,12 @@ Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 38, 1) to (start + 0, 19)
 
 Function name: async::i::{closure#0}
-Raw bytes (78): 0x[01, 01, 02, 19, 07, 1d, 21, 0e, 01, 26, 13, 04, 0c, 0d, 05, 09, 00, 0a, 01, 00, 0e, 00, 12, 05, 00, 13, 00, 18, 09, 00, 1c, 00, 21, 0d, 00, 27, 00, 2a, 15, 00, 2b, 00, 30, 1d, 01, 09, 00, 0a, 11, 00, 0e, 00, 11, 25, 00, 12, 00, 17, 29, 00, 1b, 00, 20, 1d, 00, 24, 00, 26, 21, 01, 0e, 00, 10, 03, 02, 01, 00, 02]
+Raw bytes (78): 0x[01, 01, 02, 07, 21, 19, 1d, 0e, 01, 26, 13, 04, 0c, 0d, 05, 09, 00, 0a, 01, 00, 0e, 00, 12, 05, 00, 13, 00, 18, 09, 00, 1c, 00, 21, 0d, 00, 27, 00, 2a, 15, 00, 2b, 00, 30, 1d, 01, 09, 00, 0a, 11, 00, 0e, 00, 11, 25, 00, 12, 00, 17, 29, 00, 1b, 00, 20, 1d, 00, 24, 00, 26, 21, 01, 0e, 00, 10, 03, 02, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 2
-- expression 0 operands: lhs = Counter(6), rhs = Expression(1, Add)
-- expression 1 operands: lhs = Counter(7), rhs = Counter(8)
+- expression 0 operands: lhs = Expression(1, Add), rhs = Counter(8)
+- expression 1 operands: lhs = Counter(6), rhs = Counter(7)
 Number of file 0 mappings: 14
 - Code(Counter(0)) at (prev + 38, 19) to (start + 4, 12)
 - Code(Counter(3)) at (prev + 5, 9) to (start + 0, 10)
@@ -218,15 +218,15 @@ Number of file 0 mappings: 14
 - Code(Counter(7)) at (prev + 0, 36) to (start + 0, 38)
 - Code(Counter(8)) at (prev + 1, 14) to (start + 0, 16)
 - Code(Expression(0, Add)) at (prev + 2, 1) to (start + 0, 2)
-    = (c6 + (c7 + c8))
+    = ((c6 + c7) + c8)
 
 Function name: async::j
-Raw bytes (53): 0x[01, 01, 02, 05, 07, 09, 0d, 09, 01, 31, 01, 13, 0c, 05, 14, 09, 00, 0a, 01, 00, 0e, 00, 1b, 05, 00, 1f, 00, 27, 09, 01, 09, 00, 0a, 11, 00, 0e, 00, 1a, 09, 00, 1e, 00, 20, 0d, 01, 0e, 00, 10, 03, 02, 01, 00, 02]
+Raw bytes (53): 0x[01, 01, 02, 07, 0d, 05, 09, 09, 01, 31, 01, 13, 0c, 05, 14, 09, 00, 0a, 01, 00, 0e, 00, 1b, 05, 00, 1f, 00, 27, 09, 01, 09, 00, 0a, 11, 00, 0e, 00, 1a, 09, 00, 1e, 00, 20, 0d, 01, 0e, 00, 10, 03, 02, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 2
-- expression 0 operands: lhs = Counter(1), rhs = Expression(1, Add)
-- expression 1 operands: lhs = Counter(2), rhs = Counter(3)
+- expression 0 operands: lhs = Expression(1, Add), rhs = Counter(3)
+- expression 1 operands: lhs = Counter(1), rhs = Counter(2)
 Number of file 0 mappings: 9
 - Code(Counter(0)) at (prev + 49, 1) to (start + 19, 12)
 - Code(Counter(1)) at (prev + 20, 9) to (start + 0, 10)
@@ -237,7 +237,7 @@ Number of file 0 mappings: 9
 - Code(Counter(2)) at (prev + 0, 30) to (start + 0, 32)
 - Code(Counter(3)) at (prev + 1, 14) to (start + 0, 16)
 - Code(Expression(0, Add)) at (prev + 2, 1) to (start + 0, 2)
-    = (c1 + (c2 + c3))
+    = ((c1 + c2) + c3)
 
 Function name: async::j::c
 Raw bytes (28): 0x[01, 01, 02, 01, 05, 05, 02, 04, 01, 33, 05, 01, 12, 05, 02, 0d, 00, 0e, 02, 0a, 0d, 00, 0e, 07, 02, 05, 00, 06]
@@ -283,22 +283,22 @@ Number of file 0 mappings: 5
 - Code(Zero) at (prev + 2, 1) to (start + 0, 2)
 
 Function name: async::l
-Raw bytes (37): 0x[01, 01, 04, 01, 07, 09, 05, 09, 0f, 05, 02, 05, 01, 53, 01, 01, 0c, 02, 02, 0e, 00, 10, 05, 01, 0e, 00, 10, 09, 01, 0e, 00, 10, 0b, 02, 01, 00, 02]
+Raw bytes (37): 0x[01, 01, 04, 01, 07, 05, 09, 0f, 02, 09, 05, 05, 01, 53, 01, 01, 0c, 02, 02, 0e, 00, 10, 05, 01, 0e, 00, 10, 09, 01, 0e, 00, 10, 0b, 02, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 4
 - expression 0 operands: lhs = Counter(0), rhs = Expression(1, Add)
-- expression 1 operands: lhs = Counter(2), rhs = Counter(1)
-- expression 2 operands: lhs = Counter(2), rhs = Expression(3, Add)
-- expression 3 operands: lhs = Counter(1), rhs = Expression(0, Sub)
+- expression 1 operands: lhs = Counter(1), rhs = Counter(2)
+- expression 2 operands: lhs = Expression(3, Add), rhs = Expression(0, Sub)
+- expression 3 operands: lhs = Counter(2), rhs = Counter(1)
 Number of file 0 mappings: 5
 - Code(Counter(0)) at (prev + 83, 1) to (start + 1, 12)
 - Code(Expression(0, Sub)) at (prev + 2, 14) to (start + 0, 16)
-    = (c0 - (c2 + c1))
+    = (c0 - (c1 + c2))
 - Code(Counter(1)) at (prev + 1, 14) to (start + 0, 16)
 - Code(Counter(2)) at (prev + 1, 14) to (start + 0, 16)
 - Code(Expression(2, Add)) at (prev + 2, 1) to (start + 0, 2)
-    = (c2 + (c1 + (c0 - (c2 + c1))))
+    = ((c2 + c1) + (c0 - (c1 + c2)))
 
 Function name: async::m
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 5b, 01, 00, 19]

tests/coverage/async.cov-map

@@ -1,5 +1,5 @@
 Function name: conditions::main
-Raw bytes (784): 0x[01, 01, 8e, 01, 09, 33, 37, 41, 3b, 3d, 35, 39, 05, 00, b7, 04, 09, 05, 00, 0d, 35, 26, 39, 0d, 35, 3b, 3d, 35, 39, 37, 41, 3b, 3d, 35, 39, b2, 04, 0d, b7, 04, 09, 05, 00, 45, 00, 83, 01, 49, 45, 00, 7e, 31, 83, 01, 49, 45, 00, 7a, 4d, 7e, 31, 83, 01, 49, 45, 00, 76, 51, 7a, 4d, 7e, 31, 83, 01, 49, 45, 00, a7, 01, 55, 4d, 51, a3, 01, 59, a7, 01, 55, 4d, 51, 49, 9f, 01, a3, 01, 59, a7, 01, 55, 4d, 51, 61, 00, e3, 01, 65, 61, 00, de, 01, 2d, e3, 01, 65, 61, 00, da, 01, 69, de, 01, 2d, e3, 01, 65, 61, 00, d6, 01, 6d, da, 01, 69, de, 01, 2d, e3, 01, 65, 61, 00, 8b, 02, 71, 69, 6d, 87, 02, 75, 8b, 02, 71, 69, 6d, ff, 01, 00, 65, 83, 02, 87, 02, 75, 8b, 02, 71, 69, 6d, 7d, eb, 03, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, 79, 00, d7, 02, 7d, 79, 00, d2, 02, 29, d7, 02, 7d, 79, 00, ce, 02, 81, 01, d2, 02, 29, d7, 02, 7d, 79, 00, ca, 02, 85, 01, ce, 02, 81, 01, d2, 02, 29, d7, 02, 7d, 79, 00, f3, 03, 89, 01, 81, 01, 85, 01, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, 11, 93, 04, 97, 04, 21, 9b, 04, 1d, 15, 19, 7d, eb, 03, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, e7, 03, 11, 7d, eb, 03, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, e2, 03, 25, e7, 03, 11, 7d, eb, 03, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, de, 03, 15, e2, 03, 25, e7, 03, 11, 7d, eb, 03, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, da, 03, 19, de, 03, 15, e2, 03, 25, e7, 03, 11, 7d, eb, 03, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, 9b, 04, 1d, 15, 19, 97, 04, 21, 9b, 04, 1d, 15, 19, 8f, 04, 9f, 04, 11, 93, 04, 97, 04, 21, 9b, 04, 1d, 15, 19, a3, 04, ae, 04, a7, 04, ab, 04, 25, 29, 2d, 31, b2, 04, 0d, b7, 04, 09, 05, 00, 44, 01, 03, 01, 02, 0c, 05, 02, 0d, 02, 06, 00, 02, 06, 00, 07, 03, 03, 09, 00, 0a, b7, 04, 00, 10, 00, 1d, 09, 01, 09, 01, 0a, b2, 04, 02, 0f, 00, 1c, 0d, 01, 0c, 00, 19, 26, 00, 1d, 00, 2a, 22, 00, 2e, 00, 3c, 37, 00, 3d, 02, 0a, 41, 02, 0a, 00, 0b, 33, 01, 09, 01, 12, ae, 04, 03, 09, 00, 0f, 03, 03, 09, 01, 0c, 45, 01, 0d, 02, 06, 00, 02, 06, 00, 07, 83, 01, 02, 08, 00, 15, 49, 00, 16, 02, 06, 7e, 02, 0f, 00, 1c, 7a, 01, 0c, 00, 19, 76, 00, 1d, 00, 2a, 72, 00, 2e, 00, 3c, a3, 01, 00, 3d, 02, 0a, 59, 02, 0a, 00, 0b, 9f, 01, 01, 09, 00, 17, 31, 02, 09, 00, 0f, 9b, 01, 03, 08, 00, 0c, 5d, 01, 0d, 01, 10, 61, 01, 11, 02, 0a, 00, 02, 0a, 00, 0b, e3, 01, 02, 0c, 00, 19, 65, 00, 1a, 02, 0a, de, 01, 03, 11, 00, 1e, da, 01, 01, 10, 00, 1d, d6, 01, 00, 21, 00, 2e, d2, 01, 00, 32, 00, 40, 87, 02, 00, 41, 02, 0e, 75, 02, 0e, 00, 0f, 83, 02, 01, 0d, 00, 1b, 2d, 02, 0d, 00, 13, 00, 02, 06, 00, 07, fb, 01, 02, 09, 01, 0c, 79, 01, 0d, 02, 06, 00, 02, 06, 00, 07, e7, 03, 02, 09, 00, 0a, d7, 02, 00, 10, 00, 1d, 7d, 00, 1e, 02, 06, d2, 02, 02, 0f, 00, 1c, ce, 02, 01, 0c, 00, 19, ca, 02, 00, 1d, 00, 2a, c6, 02, 00, 2e, 00, 3c, ef, 03, 00, 3d, 02, 0a, 8d, 01, 02, 0a, 00, 0b, eb, 03, 01, 09, 00, 17, 29, 02, 0d, 02, 0f, 8f, 04, 05, 09, 00, 0a, e7, 03, 00, 10, 00, 1d, 11, 00, 1e, 02, 06, e2, 03, 02, 0f, 00, 1c, de, 03, 01, 0c, 00, 19, da, 03, 00, 1d, 00, 2a, d6, 03, 00, 2e, 00, 3c, 97, 04, 00, 3d, 02, 0a, 21, 02, 0a, 00, 0b, 93, 04, 01, 09, 00, 17, 25, 02, 09, 00, 0f, 8b, 04, 02, 01, 00, 02]
+Raw bytes (784): 0x[01, 01, 8e, 01, 09, 33, 37, 41, 3b, 3d, 35, 39, 05, 00, b7, 04, 09, 05, 00, 0d, 35, 26, 39, 0d, 35, 3b, 3d, 35, 39, 37, 41, 3b, 3d, 35, 39, b2, 04, 0d, b7, 04, 09, 05, 00, 45, 00, 83, 01, 49, 45, 00, 7e, 31, 83, 01, 49, 45, 00, 7a, 4d, 7e, 31, 83, 01, 49, 45, 00, 76, 51, 7a, 4d, 7e, 31, 83, 01, 49, 45, 00, a7, 01, 55, 4d, 51, a3, 01, 59, a7, 01, 55, 4d, 51, 49, 9f, 01, a3, 01, 59, a7, 01, 55, 4d, 51, 61, 00, e3, 01, 65, 61, 00, de, 01, 2d, e3, 01, 65, 61, 00, da, 01, 69, de, 01, 2d, e3, 01, 65, 61, 00, d6, 01, 6d, da, 01, 69, de, 01, 2d, e3, 01, 65, 61, 00, 8b, 02, 71, 69, 6d, 87, 02, 75, 8b, 02, 71, 69, 6d, ff, 01, 00, 65, 83, 02, 87, 02, 75, 8b, 02, 71, 69, 6d, 7d, eb, 03, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, 79, 00, d7, 02, 7d, 79, 00, d2, 02, 29, d7, 02, 7d, 79, 00, ce, 02, 81, 01, d2, 02, 29, d7, 02, 7d, 79, 00, ca, 02, 85, 01, ce, 02, 81, 01, d2, 02, 29, d7, 02, 7d, 79, 00, f3, 03, 89, 01, 81, 01, 85, 01, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, 11, 93, 04, 97, 04, 21, 9b, 04, 1d, 15, 19, 7d, eb, 03, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, e7, 03, 11, 7d, eb, 03, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, e2, 03, 25, e7, 03, 11, 7d, eb, 03, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, de, 03, 15, e2, 03, 25, e7, 03, 11, 7d, eb, 03, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, da, 03, 19, de, 03, 15, e2, 03, 25, e7, 03, 11, 7d, eb, 03, ef, 03, 8d, 01, f3, 03, 89, 01, 81, 01, 85, 01, 9b, 04, 1d, 15, 19, 97, 04, 21, 9b, 04, 1d, 15, 19, 8f, 04, 9f, 04, 11, 93, 04, 97, 04, 21, 9b, 04, 1d, 15, 19, a3, 04, ae, 04, a7, 04, 31, ab, 04, 2d, 25, 29, b2, 04, 0d, b7, 04, 09, 05, 00, 44, 01, 03, 01, 02, 0c, 05, 02, 0d, 02, 06, 00, 02, 06, 00, 07, 03, 03, 09, 00, 0a, b7, 04, 00, 10, 00, 1d, 09, 01, 09, 01, 0a, b2, 04, 02, 0f, 00, 1c, 0d, 01, 0c, 00, 19, 26, 00, 1d, 00, 2a, 22, 00, 2e, 00, 3c, 37, 00, 3d, 02, 0a, 41, 02, 0a, 00, 0b, 33, 01, 09, 01, 12, ae, 04, 03, 09, 00, 0f, 03, 03, 09, 01, 0c, 45, 01, 0d, 02, 06, 00, 02, 06, 00, 07, 83, 01, 02, 08, 00, 15, 49, 00, 16, 02, 06, 7e, 02, 0f, 00, 1c, 7a, 01, 0c, 00, 19, 76, 00, 1d, 00, 2a, 72, 00, 2e, 00, 3c, a3, 01, 00, 3d, 02, 0a, 59, 02, 0a, 00, 0b, 9f, 01, 01, 09, 00, 17, 31, 02, 09, 00, 0f, 9b, 01, 03, 08, 00, 0c, 5d, 01, 0d, 01, 10, 61, 01, 11, 02, 0a, 00, 02, 0a, 00, 0b, e3, 01, 02, 0c, 00, 19, 65, 00, 1a, 02, 0a, de, 01, 03, 11, 00, 1e, da, 01, 01, 10, 00, 1d, d6, 01, 00, 21, 00, 2e, d2, 01, 00, 32, 00, 40, 87, 02, 00, 41, 02, 0e, 75, 02, 0e, 00, 0f, 83, 02, 01, 0d, 00, 1b, 2d, 02, 0d, 00, 13, 00, 02, 06, 00, 07, fb, 01, 02, 09, 01, 0c, 79, 01, 0d, 02, 06, 00, 02, 06, 00, 07, e7, 03, 02, 09, 00, 0a, d7, 02, 00, 10, 00, 1d, 7d, 00, 1e, 02, 06, d2, 02, 02, 0f, 00, 1c, ce, 02, 01, 0c, 00, 19, ca, 02, 00, 1d, 00, 2a, c6, 02, 00, 2e, 00, 3c, ef, 03, 00, 3d, 02, 0a, 8d, 01, 02, 0a, 00, 0b, eb, 03, 01, 09, 00, 17, 29, 02, 0d, 02, 0f, 8f, 04, 05, 09, 00, 0a, e7, 03, 00, 10, 00, 1d, 11, 00, 1e, 02, 06, e2, 03, 02, 0f, 00, 1c, de, 03, 01, 0c, 00, 19, da, 03, 00, 1d, 00, 2a, d6, 03, 00, 2e, 00, 3c, 97, 04, 00, 3d, 02, 0a, 21, 02, 0a, 00, 0b, 93, 04, 01, 09, 00, 17, 25, 02, 09, 00, 0f, 8b, 04, 02, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 142
@@ -139,9 +139,9 @@ Number of expressions: 142
 - expression 133 operands: lhs = Expression(134, Add), rhs = Counter(7)
 - expression 134 operands: lhs = Counter(5), rhs = Counter(6)
 - expression 135 operands: lhs = Expression(136, Add), rhs = Expression(139, Sub)
-- expression 136 operands: lhs = Expression(137, Add), rhs = Expression(138, Add)
-- expression 137 operands: lhs = Counter(9), rhs = Counter(10)
-- expression 138 operands: lhs = Counter(11), rhs = Counter(12)
+- expression 136 operands: lhs = Expression(137, Add), rhs = Counter(12)
+- expression 137 operands: lhs = Expression(138, Add), rhs = Counter(11)
+- expression 138 operands: lhs = Counter(9), rhs = Counter(10)
 - expression 139 operands: lhs = Expression(140, Sub), rhs = Counter(3)
 - expression 140 operands: lhs = Expression(141, Add), rhs = Counter(2)
 - expression 141 operands: lhs = Counter(1), rhs = Zero
@@ -255,5 +255,5 @@ Number of file 0 mappings: 68
     = (((c5 + c6) + c7) + c8)
 - Code(Counter(9)) at (prev + 2, 9) to (start + 0, 15)
 - Code(Expression(130, Add)) at (prev + 2, 1) to (start + 0, 2)
-    = ((c4 + (((c5 + c6) + c7) + c8)) + (((c9 + c10) + (c11 + c12)) + (((c1 + Zero) - c2) - c3)))
+    = ((c4 + (((c5 + c6) + c7) + c8)) + ((((c9 + c10) + c11) + c12) + (((c1 + Zero) - c2) - c3)))