coverage: Use a separate counter type and simplification step during counter creation

compiler/rustc_mir_transform/src/coverage/counters/tests.rs

@@ -0,0 +1,41 @@
+use std::fmt::Debug;
+
+use super::sort_and_cancel;
+
+fn flatten<T>(input: Vec<Option<T>>) -> Vec<T> {
+    input.into_iter().flatten().collect()
+}
+
+fn sort_and_cancel_and_flatten<T: Clone + Ord>(pos: Vec<T>, neg: Vec<T>) -> (Vec<T>, Vec<T>) {
+    let (pos_actual, neg_actual) = sort_and_cancel(pos, neg);
+    (flatten(pos_actual), flatten(neg_actual))
+}
+
+#[track_caller]
+fn check_test_case<T: Clone + Debug + Ord>(
+    pos: Vec<T>,
+    neg: Vec<T>,
+    pos_expected: Vec<T>,
+    neg_expected: Vec<T>,
+) {
+    eprintln!("pos = {pos:?}; neg = {neg:?}");
+    let output = sort_and_cancel_and_flatten(pos, neg);
+    assert_eq!(output, (pos_expected, neg_expected));
+}
+
+#[test]
+fn cancellation() {
+    let cases: &[(Vec<u32>, Vec<u32>, Vec<u32>, Vec<u32>)] = &[
+        (vec![], vec![], vec![], vec![]),
+        (vec![4, 2, 1, 5, 3], vec![], vec![1, 2, 3, 4, 5], vec![]),
+        (vec![5, 5, 5, 5, 5], vec![5], vec![5, 5, 5, 5], vec![]),
+        (vec![1, 1, 2, 2, 3, 3], vec![1, 2, 3], vec![1, 2, 3], vec![]),
+        (vec![1, 1, 2, 2, 3, 3], vec![2, 4, 2], vec![1, 1, 3, 3], vec![4]),
+    ];
+
+    for (pos, neg, pos_expected, neg_expected) in cases {
+        check_test_case(pos.to_vec(), neg.to_vec(), pos_expected.to_vec(), neg_expected.to_vec());
+        // Same test case, but with its inputs flipped and its outputs flipped.
+        check_test_case(neg.to_vec(), pos.to_vec(), neg_expected.to_vec(), pos_expected.to_vec());
+    }
+}

compiler/rustc_mir_transform/src/coverage/mod.rs

@@ -25,7 +25,7 @@ use rustc_span::source_map::SourceMap;
 use rustc_span::{BytePos, Pos, SourceFile, Span};
 use tracing::{debug, debug_span, trace};
 
-use crate::coverage::counters::{CounterIncrementSite, CoverageCounters};
+use crate::coverage::counters::{CoverageCounters, Site};
 use crate::coverage::graph::CoverageGraph;
 use crate::coverage::mappings::ExtractedMappings;
 
@@ -265,13 +265,13 @@ fn inject_coverage_statements<'tcx>(
     coverage_counters: &CoverageCounters,
 ) {
     // Inject counter-increment statements into MIR.
-    for (id, counter_increment_site) in coverage_counters.counter_increment_sites() {
+    for (id, site) in coverage_counters.counter_increment_sites() {
         // Determine the block to inject a counter-increment statement into.
         // For BCB nodes this is just their first block, but for edges we need
         // to create a new block between the two BCBs, and inject into that.
-        let target_bb = match *counter_increment_site {
-            CounterIncrementSite::Node { bcb } => basic_coverage_blocks[bcb].leader_bb(),
-            CounterIncrementSite::Edge { from_bcb, to_bcb } => {
+        let target_bb = match site {
+            Site::Node { bcb } => basic_coverage_blocks[bcb].leader_bb(),
+            Site::Edge { from_bcb, to_bcb } => {
                 // Create a new block between the last block of `from_bcb` and
                 // the first block of `to_bcb`.
                 let from_bb = basic_coverage_blocks[from_bcb].last_bb();

tests/coverage/abort.cov-map

@@ -1,34 +1,34 @@
 Function name: abort::main
-Raw bytes (89): 0x[01, 01, 0a, 01, 27, 05, 09, 03, 0d, 22, 11, 03, 0d, 03, 0d, 22, 15, 03, 0d, 03, 0d, 05, 09, 0d, 01, 0d, 01, 01, 1b, 03, 02, 0b, 00, 18, 22, 01, 0c, 00, 19, 11, 00, 1a, 02, 0a, 0e, 02, 09, 00, 0a, 22, 02, 0c, 00, 19, 15, 00, 1a, 00, 31, 1a, 00, 30, 00, 31, 22, 04, 0c, 00, 19, 05, 00, 1a, 00, 31, 09, 00, 30, 00, 31, 27, 01, 09, 00, 17, 0d, 02, 05, 01, 02]
+Raw bytes (89): 0x[01, 01, 0a, 07, 09, 01, 05, 03, 0d, 03, 13, 0d, 11, 03, 0d, 03, 1f, 0d, 15, 03, 0d, 05, 09, 0d, 01, 0d, 01, 01, 1b, 03, 02, 0b, 00, 18, 22, 01, 0c, 00, 19, 11, 00, 1a, 02, 0a, 0e, 02, 09, 00, 0a, 22, 02, 0c, 00, 19, 15, 00, 1a, 00, 31, 1a, 00, 30, 00, 31, 22, 04, 0c, 00, 19, 05, 00, 1a, 00, 31, 09, 00, 30, 00, 31, 27, 01, 09, 00, 17, 0d, 02, 05, 01, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 10
-- expression 0 operands: lhs = Counter(0), rhs = Expression(9, Add)
-- expression 1 operands: lhs = Counter(1), rhs = Counter(2)
+- expression 0 operands: lhs = Expression(1, Add), rhs = Counter(2)
+- expression 1 operands: lhs = Counter(0), rhs = Counter(1)
 - expression 2 operands: lhs = Expression(0, Add), rhs = Counter(3)
-- expression 3 operands: lhs = Expression(8, Sub), rhs = Counter(4)
-- expression 4 operands: lhs = Expression(0, Add), rhs = Counter(3)
+- expression 3 operands: lhs = Expression(0, Add), rhs = Expression(4, Add)
+- expression 4 operands: lhs = Counter(3), rhs = Counter(4)
 - expression 5 operands: lhs = Expression(0, Add), rhs = Counter(3)
-- expression 6 operands: lhs = Expression(8, Sub), rhs = Counter(5)
-- expression 7 operands: lhs = Expression(0, Add), rhs = Counter(3)
+- expression 6 operands: lhs = Expression(0, Add), rhs = Expression(7, Add)
+- expression 7 operands: lhs = Counter(3), rhs = Counter(5)
 - expression 8 operands: lhs = Expression(0, Add), rhs = Counter(3)
 - expression 9 operands: lhs = Counter(1), rhs = Counter(2)
 Number of file 0 mappings: 13
 - Code(Counter(0)) at (prev + 13, 1) to (start + 1, 27)
 - Code(Expression(0, Add)) at (prev + 2, 11) to (start + 0, 24)
-    = (c0 + (c1 + c2))
+    = ((c0 + c1) + c2)
 - Code(Expression(8, Sub)) at (prev + 1, 12) to (start + 0, 25)
-    = ((c0 + (c1 + c2)) - c3)
+    = (((c0 + c1) + c2) - c3)
 - Code(Counter(4)) at (prev + 0, 26) to (start + 2, 10)
 - Code(Expression(3, Sub)) at (prev + 2, 9) to (start + 0, 10)
-    = (((c0 + (c1 + c2)) - c3) - c4)
+    = (((c0 + c1) + c2) - (c3 + c4))
 - Code(Expression(8, Sub)) at (prev + 2, 12) to (start + 0, 25)
-    = ((c0 + (c1 + c2)) - c3)
+    = (((c0 + c1) + c2) - c3)
 - Code(Counter(5)) at (prev + 0, 26) to (start + 0, 49)
 - Code(Expression(6, Sub)) at (prev + 0, 48) to (start + 0, 49)
-    = (((c0 + (c1 + c2)) - c3) - c5)
+    = (((c0 + c1) + c2) - (c3 + c5))
 - Code(Expression(8, Sub)) at (prev + 4, 12) to (start + 0, 25)
-    = ((c0 + (c1 + c2)) - c3)
+    = (((c0 + c1) + c2) - c3)
 - Code(Counter(1)) at (prev + 0, 26) to (start + 0, 49)
 - Code(Counter(2)) at (prev + 0, 48) to (start + 0, 49)
 - Code(Expression(9, Add)) at (prev + 1, 9) to (start + 0, 23)

tests/coverage/assert.cov-map

@@ -1,29 +1,30 @@
 Function name: assert::main
-Raw bytes (65): 0x[01, 01, 08, 01, 1b, 05, 1f, 09, 0d, 03, 11, 16, 05, 03, 11, 05, 1f, 09, 0d, 09, 01, 09, 01, 01, 1b, 03, 02, 0b, 00, 18, 16, 01, 0c, 00, 1a, 05, 00, 1b, 02, 0a, 12, 02, 13, 00, 20, 09, 00, 21, 02, 0a, 0d, 02, 09, 00, 0a, 1b, 01, 09, 00, 17, 11, 02, 05, 01, 02]
+Raw bytes (67): 0x[01, 01, 09, 07, 0d, 0b, 09, 01, 05, 03, 11, 17, 11, 1b, 0d, 01, 09, 23, 0d, 05, 09, 09, 01, 09, 01, 01, 1b, 03, 02, 0b, 00, 18, 0e, 01, 0c, 00, 1a, 05, 00, 1b, 02, 0a, 12, 02, 13, 00, 20, 09, 00, 21, 02, 0a, 0d, 02, 09, 00, 0a, 1f, 01, 09, 00, 17, 11, 02, 05, 01, 02]
 Number of files: 1
 - file 0 => global file 1
-Number of expressions: 8
-- expression 0 operands: lhs = Counter(0), rhs = Expression(6, Add)
-- expression 1 operands: lhs = Counter(1), rhs = Expression(7, Add)
-- expression 2 operands: lhs = Counter(2), rhs = Counter(3)
+Number of expressions: 9
+- expression 0 operands: lhs = Expression(1, Add), rhs = Counter(3)
+- expression 1 operands: lhs = Expression(2, Add), rhs = Counter(2)
+- expression 2 operands: lhs = Counter(0), rhs = Counter(1)
 - expression 3 operands: lhs = Expression(0, Add), rhs = Counter(4)
-- expression 4 operands: lhs = Expression(5, Sub), rhs = Counter(1)
-- expression 5 operands: lhs = Expression(0, Add), rhs = Counter(4)
-- expression 6 operands: lhs = Counter(1), rhs = Expression(7, Add)
-- expression 7 operands: lhs = Counter(2), rhs = Counter(3)
+- expression 4 operands: lhs = Expression(5, Add), rhs = Counter(4)
+- expression 5 operands: lhs = Expression(6, Add), rhs = Counter(3)
+- expression 6 operands: lhs = Counter(0), rhs = Counter(2)
+- expression 7 operands: lhs = Expression(8, Add), rhs = Counter(3)
+- expression 8 operands: lhs = Counter(1), rhs = Counter(2)
 Number of file 0 mappings: 9
 - Code(Counter(0)) at (prev + 9, 1) to (start + 1, 27)
 - Code(Expression(0, Add)) at (prev + 2, 11) to (start + 0, 24)
-    = (c0 + (c1 + (c2 + c3)))
-- Code(Expression(5, Sub)) at (prev + 1, 12) to (start + 0, 26)
-    = ((c0 + (c1 + (c2 + c3))) - c4)
+    = (((c0 + c1) + c2) + c3)
+- Code(Expression(3, Sub)) at (prev + 1, 12) to (start + 0, 26)
+    = ((((c0 + c1) + c2) + c3) - c4)
 - Code(Counter(1)) at (prev + 0, 27) to (start + 2, 10)
 - Code(Expression(4, Sub)) at (prev + 2, 19) to (start + 0, 32)
-    = (((c0 + (c1 + (c2 + c3))) - c4) - c1)
+    = (((c0 + c2) + c3) - c4)
 - Code(Counter(2)) at (prev + 0, 33) to (start + 2, 10)
 - Code(Counter(3)) at (prev + 2, 9) to (start + 0, 10)
-- Code(Expression(6, Add)) at (prev + 1, 9) to (start + 0, 23)
-    = (c1 + (c2 + c3))
+- Code(Expression(7, Add)) at (prev + 1, 9) to (start + 0, 23)
+    = ((c1 + c2) + c3)
 - Code(Counter(4)) at (prev + 2, 5) to (start + 1, 2)
 Highest counter ID seen: c4
 

tests/coverage/async.cov-map

@@ -155,25 +155,25 @@ Number of file 0 mappings: 1
 Highest counter ID seen: c0
 
 Function name: async::i::{closure#0}
-Raw bytes (63): 0x[01, 01, 02, 07, 19, 11, 15, 0b, 01, 2d, 13, 04, 0c, 09, 05, 09, 00, 0a, 01, 00, 0e, 00, 18, 05, 00, 1c, 00, 21, 09, 00, 27, 00, 30, 15, 01, 09, 00, 0a, 0d, 00, 0e, 00, 17, 1d, 00, 1b, 00, 20, 15, 00, 24, 00, 26, 19, 01, 0e, 00, 10, 03, 02, 01, 00, 02]
+Raw bytes (63): 0x[01, 01, 02, 07, 15, 0d, 11, 0b, 01, 2d, 13, 04, 0c, 09, 05, 09, 00, 0a, 01, 00, 0e, 00, 18, 05, 00, 1c, 00, 21, 09, 00, 27, 00, 30, 11, 01, 09, 00, 0a, 19, 00, 0e, 00, 17, 1d, 00, 1b, 00, 20, 11, 00, 24, 00, 26, 15, 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 = Expression(1, Add), rhs = Counter(6)
-- expression 1 operands: lhs = Counter(4), rhs = Counter(5)
+- expression 0 operands: lhs = Expression(1, Add), rhs = Counter(5)
+- expression 1 operands: lhs = Counter(3), rhs = Counter(4)
 Number of file 0 mappings: 11
 - Code(Counter(0)) at (prev + 45, 19) to (start + 4, 12)
 - Code(Counter(2)) at (prev + 5, 9) to (start + 0, 10)
 - Code(Counter(0)) at (prev + 0, 14) to (start + 0, 24)
 - Code(Counter(1)) at (prev + 0, 28) to (start + 0, 33)
 - Code(Counter(2)) at (prev + 0, 39) to (start + 0, 48)
-- Code(Counter(5)) at (prev + 1, 9) to (start + 0, 10)
-- Code(Counter(3)) at (prev + 0, 14) to (start + 0, 23)
+- Code(Counter(4)) at (prev + 1, 9) to (start + 0, 10)
+- Code(Counter(6)) at (prev + 0, 14) to (start + 0, 23)
 - Code(Counter(7)) at (prev + 0, 27) to (start + 0, 32)
-- Code(Counter(5)) at (prev + 0, 36) to (start + 0, 38)
-- Code(Counter(6)) at (prev + 1, 14) to (start + 0, 16)
+- Code(Counter(4)) at (prev + 0, 36) to (start + 0, 38)
+- Code(Counter(5)) at (prev + 1, 14) to (start + 0, 16)
 - Code(Expression(0, Add)) at (prev + 2, 1) to (start + 0, 2)
-    = ((c4 + c5) + c6)
+    = ((c3 + c4) + c5)
 Highest counter ID seen: c7
 
 Function name: async::j
@@ -243,22 +243,19 @@ Number of file 0 mappings: 5
 Highest counter ID seen: (none)
 
 Function name: async::l
-Raw bytes (37): 0x[01, 01, 04, 01, 07, 05, 09, 0f, 02, 09, 05, 05, 01, 52, 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 (33): 0x[01, 01, 02, 01, 07, 05, 09, 05, 01, 52, 01, 01, 0c, 02, 02, 0e, 00, 10, 09, 01, 0e, 00, 10, 05, 01, 0e, 00, 10, 01, 02, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
-Number of expressions: 4
+Number of expressions: 2
 - expression 0 operands: lhs = Counter(0), rhs = Expression(1, Add)
 - 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 + 82, 1) to (start + 1, 12)
 - Code(Expression(0, Sub)) at (prev + 2, 14) to (start + 0, 16)
     = (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 - (c1 + c2)))
+- Code(Counter(1)) at (prev + 1, 14) to (start + 0, 16)
+- Code(Counter(0)) at (prev + 2, 1) to (start + 0, 2)
 Highest counter ID seen: c2
 
 Function name: async::m

tests/coverage/branch/guard.cov-map

@@ -1,5 +1,5 @@
 Function name: guard::branch_match_guard
-Raw bytes (85): 0x[01, 01, 06, 19, 0d, 05, 09, 0f, 15, 13, 11, 17, 0d, 05, 09, 0d, 01, 0c, 01, 01, 10, 1d, 03, 0b, 00, 0c, 15, 01, 14, 02, 0a, 0d, 03, 0e, 00, 0f, 19, 00, 14, 00, 19, 20, 0d, 02, 00, 14, 00, 1e, 0d, 00, 1d, 02, 0a, 11, 03, 0e, 00, 0f, 1d, 00, 14, 00, 19, 20, 11, 09, 00, 14, 00, 1e, 11, 00, 1d, 02, 0a, 17, 03, 0e, 02, 0a, 0b, 04, 01, 00, 02]
+Raw bytes (85): 0x[01, 01, 06, 19, 0d, 05, 09, 0f, 15, 13, 11, 17, 0d, 05, 09, 0d, 01, 0c, 01, 01, 10, 02, 03, 0b, 00, 0c, 15, 01, 14, 02, 0a, 0d, 03, 0e, 00, 0f, 19, 00, 14, 00, 19, 20, 0d, 02, 00, 14, 00, 1e, 0d, 00, 1d, 02, 0a, 11, 03, 0e, 00, 0f, 02, 00, 14, 00, 19, 20, 11, 05, 00, 14, 00, 1e, 11, 00, 1d, 02, 0a, 17, 03, 0e, 02, 0a, 0b, 04, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 6
@@ -11,7 +11,8 @@ Number of expressions: 6
 - expression 5 operands: lhs = Counter(1), rhs = Counter(2)
 Number of file 0 mappings: 13
 - Code(Counter(0)) at (prev + 12, 1) to (start + 1, 16)
-- Code(Counter(7)) at (prev + 3, 11) to (start + 0, 12)
+- Code(Expression(0, Sub)) at (prev + 3, 11) to (start + 0, 12)
+    = (c6 - c3)
 - Code(Counter(5)) at (prev + 1, 20) to (start + 2, 10)
 - Code(Counter(3)) at (prev + 3, 14) to (start + 0, 15)
 - Code(Counter(6)) at (prev + 0, 20) to (start + 0, 25)
@@ -20,14 +21,15 @@ Number of file 0 mappings: 13
     false = (c6 - c3)
 - Code(Counter(3)) at (prev + 0, 29) to (start + 2, 10)
 - Code(Counter(4)) at (prev + 3, 14) to (start + 0, 15)
-- Code(Counter(7)) at (prev + 0, 20) to (start + 0, 25)
-- Branch { true: Counter(4), false: Counter(2) } at (prev + 0, 20) to (start + 0, 30)
+- Code(Expression(0, Sub)) at (prev + 0, 20) to (start + 0, 25)
+    = (c6 - c3)
+- Branch { true: Counter(4), false: Counter(1) } at (prev + 0, 20) to (start + 0, 30)
     true  = c4
-    false = c2
+    false = c1
 - Code(Counter(4)) at (prev + 0, 29) to (start + 2, 10)
 - Code(Expression(5, Add)) at (prev + 3, 14) to (start + 2, 10)
     = (c1 + c2)
 - Code(Expression(2, Add)) at (prev + 4, 1) to (start + 0, 2)
     = ((((c1 + c2) + c3) + c4) + c5)
-Highest counter ID seen: c7
+Highest counter ID seen: c6
 

tests/coverage/branch/if.cov-map

@@ -1,27 +1,29 @@
 Function name: if::branch_and
-Raw bytes (56): 0x[01, 01, 04, 05, 09, 0d, 02, 11, 0f, 0d, 02, 08, 01, 2b, 01, 01, 10, 05, 03, 08, 00, 09, 20, 09, 02, 00, 08, 00, 09, 09, 00, 0d, 00, 0e, 20, 11, 0d, 00, 0d, 00, 0e, 11, 00, 0f, 02, 06, 0f, 02, 0c, 02, 06, 0b, 03, 01, 00, 02]
+Raw bytes (60): 0x[01, 01, 06, 05, 09, 0b, 09, 05, 11, 13, 09, 17, 11, 05, 0d, 08, 01, 2b, 01, 01, 10, 05, 03, 08, 00, 09, 20, 09, 02, 00, 08, 00, 09, 09, 00, 0d, 00, 0e, 20, 0d, 11, 00, 0d, 00, 0e, 0d, 00, 0f, 02, 06, 06, 02, 0c, 02, 06, 0e, 03, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
-Number of expressions: 4
+Number of expressions: 6
 - expression 0 operands: lhs = Counter(1), rhs = Counter(2)
-- expression 1 operands: lhs = Counter(3), rhs = Expression(0, Sub)
-- expression 2 operands: lhs = Counter(4), rhs = Expression(3, Add)
-- expression 3 operands: lhs = Counter(3), rhs = Expression(0, Sub)
+- expression 1 operands: lhs = Expression(2, Add), rhs = Counter(2)
+- expression 2 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 3 operands: lhs = Expression(4, Add), rhs = Counter(2)
+- expression 4 operands: lhs = Expression(5, Add), rhs = Counter(4)
+- expression 5 operands: lhs = Counter(1), rhs = Counter(3)
 Number of file 0 mappings: 8
 - Code(Counter(0)) at (prev + 43, 1) to (start + 1, 16)
 - Code(Counter(1)) at (prev + 3, 8) to (start + 0, 9)
 - Branch { true: Counter(2), false: Expression(0, Sub) } at (prev + 0, 8) to (start + 0, 9)
     true  = c2
     false = (c1 - c2)
 - Code(Counter(2)) at (prev + 0, 13) to (start + 0, 14)
-- Branch { true: Counter(4), false: Counter(3) } at (prev + 0, 13) to (start + 0, 14)
-    true  = c4
-    false = c3
-- Code(Counter(4)) at (prev + 0, 15) to (start + 2, 6)
-- Code(Expression(3, Add)) at (prev + 2, 12) to (start + 2, 6)
-    = (c3 + (c1 - c2))
-- Code(Expression(2, Add)) at (prev + 3, 1) to (start + 0, 2)
-    = (c4 + (c3 + (c1 - c2)))
+- Branch { true: Counter(3), false: Counter(4) } at (prev + 0, 13) to (start + 0, 14)
+    true  = c3
+    false = c4
+- Code(Counter(3)) at (prev + 0, 15) to (start + 2, 6)
+- Code(Expression(1, Sub)) at (prev + 2, 12) to (start + 2, 6)
+    = ((c1 + c4) - c2)
+- Code(Expression(3, Sub)) at (prev + 3, 1) to (start + 0, 2)
+    = (((c1 + c3) + c4) - c2)
 Highest counter ID seen: c4
 
 Function name: if::branch_not