rust-lang · bors · Oct 11, 2024 · Oct 8, 2024
diff --git a/src/tools/coverage-dump/src/covfun.rs b/src/tools/coverage-dump/src/covfun.rs
@@ -56,13 +56,19 @@ pub(crate) fn dump_covfun_mappings(
             expression_resolver.push_operands(lhs, rhs);
         }
 
+        let mut max_counter = None;
         for i in 0..num_files {
             let num_mappings = parser.read_uleb128_u32()?;
             println!("Number of file {i} mappings: {num_mappings}");
 
             for _ in 0..num_mappings {
                 let (kind, region) = parser.read_mapping_kind_and_region()?;
                 println!("- {kind:?} at {region:?}");
+                kind.for_each_term(|term| {
+                    if let CovTerm::Counter(n) = term {
+                        max_counter = max_counter.max(Some(n));
+                    }
+                });
 
                 match kind {
                     // Also print expression mappings in resolved form.
@@ -83,6 +89,16 @@ pub(crate) fn dump_covfun_mappings(
         }
 
         parser.ensure_empty()?;
+
+        // Printing the highest counter ID seen in the functions mappings makes
+        // it easier to determine whether a change to coverage instrumentation
+        // has increased or decreased the number of physical counters needed.
+        // (It's possible for the generated code to have more counters that
+        // aren't used by any mappings, but that should hopefully be rare.)
+        println!("Highest counter ID seen: {}", match max_counter {
+            Some(id) => format!("c{id}"),
+            None => "(none)".to_owned(),
+        });
         println!();
     }
     Ok(())
@@ -271,6 +287,32 @@ enum MappingKind {
     },
 }
 
+impl MappingKind {
+    fn for_each_term(&self, mut callback: impl FnMut(CovTerm)) {
+        match *self {
+            Self::Code(term) => callback(term),
+            Self::Gap(term) => callback(term),
+            Self::Expansion(_id) => {}
+            Self::Skip => {}
+            Self::Branch { r#true, r#false } => {
+                callback(r#true);
+                callback(r#false);
+            }
+            Self::MCDCBranch {
+                r#true,
+                r#false,
+                condition_id: _,
+                true_next_id: _,
+                false_next_id: _,
+            } => {
+                callback(r#true);
+                callback(r#false);
+            }
+            Self::MCDCDecision { bitmap_idx: _, conditions_num: _ } => {}
+        }
+    }
+}
+
 struct MappingRegion {
     /// Offset of this region's start line, relative to the *start line* of
     /// the *previous mapping* (or 0). Line numbers are 1-based.

diff --git a/tests/coverage/abort.cov-map b/tests/coverage/abort.cov-map
@@ -34,6 +34,7 @@ Number of file 0 mappings: 13
 - Code(Expression(9, Add)) at (prev + 1, 9) to (start + 0, 23)
     = (c1 + c2)
 - Code(Counter(3)) at (prev + 2, 5) to (start + 1, 2)
+Highest counter ID seen: c5
 
 Function name: abort::might_abort
 Raw bytes (21): 0x[01, 01, 01, 01, 05, 03, 01, 03, 01, 01, 14, 05, 02, 09, 01, 24, 02, 02, 0c, 03, 02]
@@ -46,4 +47,5 @@ Number of file 0 mappings: 3
 - Code(Counter(1)) at (prev + 2, 9) to (start + 1, 36)
 - Code(Expression(0, Sub)) at (prev + 2, 12) to (start + 3, 2)
     = (c0 - c1)
+Highest counter ID seen: c1
 
diff --git a/tests/coverage/assert-ne.cov-map b/tests/coverage/assert-ne.cov-map
@@ -10,4 +10,5 @@ Number of file 0 mappings: 4
 - Code(Expression(0, Sub)) at (prev + 2, 13) to (start + 0, 19)
     = (c0 - c1)
 - Code(Counter(2)) at (prev + 3, 5) to (start + 1, 2)
+Highest counter ID seen: c2
 
diff --git a/tests/coverage/assert.cov-map b/tests/coverage/assert.cov-map
@@ -25,6 +25,7 @@ Number of file 0 mappings: 9
 - Code(Expression(6, 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
 
 Function name: assert::might_fail_assert
 Raw bytes (21): 0x[01, 01, 01, 01, 05, 03, 01, 04, 01, 02, 0f, 02, 02, 25, 00, 3d, 05, 01, 01, 00, 02]
@@ -37,4 +38,5 @@ Number of file 0 mappings: 3
 - Code(Expression(0, Sub)) at (prev + 2, 37) to (start + 0, 61)
     = (c0 - c1)
 - Code(Counter(1)) at (prev + 1, 1) to (start + 0, 2)
+Highest counter ID seen: c1
 
diff --git a/tests/coverage/assert_not.cov-map b/tests/coverage/assert_not.cov-map
@@ -13,4 +13,5 @@ Number of file 0 mappings: 5
 - Code(Counter(3)) at (prev + 1, 5) to (start + 0, 22)
 - Code(Expression(1, Sub)) at (prev + 1, 1) to (start + 0, 2)
     = (c3 - Zero)
+Highest counter ID seen: c3
 
diff --git a/tests/coverage/async.cov-map b/tests/coverage/async.cov-map
@@ -5,6 +5,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 12, 1) to (start + 0, 25)
+Highest counter ID seen: c0
 
 Function name: async::c::{closure#0}
 Raw bytes (26): 0x[01, 01, 01, 01, 05, 04, 01, 0c, 19, 01, 0e, 05, 02, 09, 00, 0a, 02, 02, 09, 00, 0a, 01, 02, 01, 00, 02]
@@ -18,6 +19,7 @@ Number of file 0 mappings: 4
 - Code(Expression(0, Sub)) at (prev + 2, 9) to (start + 0, 10)
     = (c0 - c1)
 - Code(Counter(0)) at (prev + 2, 1) to (start + 0, 2)
+Highest counter ID seen: c1
 
 Function name: async::d
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 14, 01, 00, 14]
@@ -26,6 +28,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 20, 1) to (start + 0, 20)
+Highest counter ID seen: c0
 
 Function name: async::d::{closure#0}
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 14, 14, 00, 19]
@@ -34,6 +37,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 20, 20) to (start + 0, 25)
+Highest counter ID seen: c0
 
 Function name: async::e (unused)
 Raw bytes (9): 0x[01, 01, 00, 01, 00, 16, 01, 00, 14]
@@ -42,6 +46,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Zero) at (prev + 22, 1) to (start + 0, 20)
+Highest counter ID seen: (none)
 
 Function name: async::e::{closure#0} (unused)
 Raw bytes (9): 0x[01, 01, 00, 01, 00, 16, 14, 00, 19]
@@ -50,6 +55,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Zero) at (prev + 22, 20) to (start + 0, 25)
+Highest counter ID seen: (none)
 
 Function name: async::f
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 18, 01, 00, 14]
@@ -58,6 +64,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 24, 1) to (start + 0, 20)
+Highest counter ID seen: c0
 
 Function name: async::f::{closure#0}
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 18, 14, 00, 19]
@@ -66,6 +73,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 24, 20) to (start + 0, 25)
+Highest counter ID seen: c0
 
 Function name: async::foo (unused)
 Raw bytes (9): 0x[01, 01, 00, 01, 00, 1a, 01, 00, 1e]
@@ -74,6 +82,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Zero) at (prev + 26, 1) to (start + 0, 30)
+Highest counter ID seen: (none)
 
 Function name: async::foo::{closure#0} (unused)
 Raw bytes (9): 0x[01, 01, 00, 01, 00, 1a, 1e, 00, 2d]
@@ -82,6 +91,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Zero) at (prev + 26, 30) to (start + 0, 45)
+Highest counter ID seen: (none)
 
 Function name: async::g
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 1c, 01, 00, 17]
@@ -90,6 +100,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 28, 1) to (start + 0, 23)
+Highest counter ID seen: c0
 
 Function name: async::g::{closure#0} (unused)
 Raw bytes (59): 0x[01, 01, 00, 0b, 00, 1c, 17, 01, 0c, 00, 02, 09, 00, 0a, 00, 00, 0e, 00, 17, 00, 00, 1b, 00, 1c, 00, 00, 20, 00, 22, 00, 01, 09, 00, 0a, 00, 00, 0e, 00, 17, 00, 00, 1b, 00, 1c, 00, 00, 20, 00, 22, 00, 01, 0e, 00, 10, 00, 02, 01, 00, 02]
@@ -108,6 +119,7 @@ Number of file 0 mappings: 11
 - Code(Zero) at (prev + 0, 32) to (start + 0, 34)
 - Code(Zero) at (prev + 1, 14) to (start + 0, 16)
 - Code(Zero) at (prev + 2, 1) to (start + 0, 2)
+Highest counter ID seen: (none)
 
 Function name: async::h
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 24, 01, 00, 16]
@@ -116,6 +128,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 36, 1) to (start + 0, 22)
+Highest counter ID seen: c0
 
 Function name: async::h::{closure#0} (unused)
 Raw bytes (39): 0x[01, 01, 00, 07, 00, 24, 16, 03, 0c, 00, 04, 09, 00, 0a, 00, 00, 0e, 00, 19, 00, 00, 1a, 00, 1b, 00, 00, 20, 00, 22, 00, 01, 0e, 00, 10, 00, 02, 01, 00, 02]
@@ -130,6 +143,7 @@ Number of file 0 mappings: 7
 - Code(Zero) at (prev + 0, 32) to (start + 0, 34)
 - Code(Zero) at (prev + 1, 14) to (start + 0, 16)
 - Code(Zero) at (prev + 2, 1) to (start + 0, 2)
+Highest counter ID seen: (none)
 
 Function name: async::i
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 2d, 01, 00, 13]
@@ -138,6 +152,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 45, 1) to (start + 0, 19)
+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]
@@ -159,6 +174,7 @@ Number of file 0 mappings: 11
 - Code(Counter(6)) at (prev + 1, 14) to (start + 0, 16)
 - Code(Expression(0, Add)) at (prev + 2, 1) to (start + 0, 2)
     = ((c4 + c5) + c6)
+Highest counter ID seen: c7
 
 Function name: async::j
 Raw bytes (58): 0x[01, 01, 02, 07, 0d, 05, 09, 0a, 01, 38, 01, 00, 0d, 01, 0b, 0b, 00, 0c, 05, 01, 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]
@@ -179,6 +195,7 @@ Number of file 0 mappings: 10
 - 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)
+Highest counter ID seen: c4
 
 Function name: async::j::c
 Raw bytes (26): 0x[01, 01, 01, 01, 05, 04, 01, 3a, 05, 01, 12, 05, 02, 0d, 00, 0e, 02, 02, 0d, 00, 0e, 01, 02, 05, 00, 06]
@@ -192,6 +209,7 @@ Number of file 0 mappings: 4
 - Code(Expression(0, Sub)) at (prev + 2, 13) to (start + 0, 14)
     = (c0 - c1)
 - Code(Counter(0)) at (prev + 2, 5) to (start + 0, 6)
+Highest counter ID seen: c1
 
 Function name: async::j::d
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 41, 05, 00, 17]
@@ -200,6 +218,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 65, 5) to (start + 0, 23)
+Highest counter ID seen: c0
 
 Function name: async::j::f
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 42, 05, 00, 17]
@@ -208,6 +227,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 66, 5) to (start + 0, 23)
+Highest counter ID seen: c0
 
 Function name: async::k (unused)
 Raw bytes (29): 0x[01, 01, 00, 05, 00, 4a, 01, 01, 0c, 00, 02, 0e, 00, 10, 00, 01, 0e, 00, 10, 00, 01, 0e, 00, 10, 00, 02, 01, 00, 02]
@@ -220,6 +240,7 @@ Number of file 0 mappings: 5
 - Code(Zero) at (prev + 1, 14) to (start + 0, 16)
 - Code(Zero) at (prev + 1, 14) to (start + 0, 16)
 - Code(Zero) at (prev + 2, 1) to (start + 0, 2)
+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]
@@ -238,6 +259,7 @@ Number of file 0 mappings: 5
 - 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)))
+Highest counter ID seen: c2
 
 Function name: async::m
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 5a, 01, 00, 19]
@@ -246,6 +268,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 90, 1) to (start + 0, 25)
+Highest counter ID seen: c0
 
 Function name: async::m::{closure#0} (unused)
 Raw bytes (9): 0x[01, 01, 00, 01, 00, 5a, 19, 00, 22]
@@ -254,6 +277,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Zero) at (prev + 90, 25) to (start + 0, 34)
+Highest counter ID seen: (none)
 
 Function name: async::main
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 5c, 01, 08, 02]
@@ -262,4 +286,5 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 92, 1) to (start + 8, 2)
+Highest counter ID seen: c0
 
diff --git a/tests/coverage/async2.cov-map b/tests/coverage/async2.cov-map
@@ -5,6 +5,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 16, 1) to (start + 0, 23)
+Highest counter ID seen: c0
 
 Function name: async2::async_func::{closure#0}
 Raw bytes (24): 0x[01, 01, 00, 04, 01, 10, 17, 03, 09, 05, 03, 0a, 02, 06, 00, 02, 06, 00, 07, 01, 01, 01, 00, 02]
@@ -16,6 +17,7 @@ Number of file 0 mappings: 4
 - Code(Counter(1)) at (prev + 3, 10) to (start + 2, 6)
 - Code(Zero) at (prev + 2, 6) to (start + 0, 7)
 - Code(Counter(0)) at (prev + 1, 1) to (start + 0, 2)
+Highest counter ID seen: c1
 
 Function name: async2::async_func_just_println
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 18, 01, 00, 24]
@@ -24,6 +26,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 24, 1) to (start + 0, 36)
+Highest counter ID seen: c0
 
 Function name: async2::async_func_just_println::{closure#0}
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 18, 24, 02, 02]
@@ -32,6 +35,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 24, 36) to (start + 2, 2)
+Highest counter ID seen: c0
 
 Function name: async2::main
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 1c, 01, 07, 02]
@@ -40,6 +44,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Counter(0)) at (prev + 28, 1) to (start + 7, 2)
+Highest counter ID seen: c0
 
 Function name: async2::non_async_func
 Raw bytes (24): 0x[01, 01, 00, 04, 01, 08, 01, 03, 09, 05, 03, 0a, 02, 06, 00, 02, 06, 00, 07, 01, 01, 01, 00, 02]
@@ -51,4 +56,5 @@ Number of file 0 mappings: 4
 - Code(Counter(1)) at (prev + 3, 10) to (start + 2, 6)
 - Code(Zero) at (prev + 2, 6) to (start + 0, 7)
 - Code(Counter(0)) at (prev + 1, 1) to (start + 0, 2)
+Highest counter ID seen: c1
 
diff --git a/tests/coverage/async_block.cov-map b/tests/coverage/async_block.cov-map
@@ -12,6 +12,7 @@ Number of file 0 mappings: 6
 - Code(Counter(1)) at (prev + 0, 20) to (start + 1, 22)
 - Code(Counter(1)) at (prev + 7, 10) to (start + 2, 6)
 - Code(Counter(0)) at (prev + 3, 1) to (start + 0, 2)
+Highest counter ID seen: c1
 
 Function name: async_block::main::{closure#0}
 Raw bytes (26): 0x[01, 01, 01, 01, 05, 04, 01, 0a, 1c, 01, 17, 05, 01, 18, 02, 0e, 02, 02, 14, 02, 0e, 01, 03, 09, 00, 0a]
@@ -25,4 +26,5 @@ Number of file 0 mappings: 4
 - Code(Expression(0, Sub)) at (prev + 2, 20) to (start + 2, 14)
     = (c0 - c1)
 - Code(Counter(0)) at (prev + 3, 9) to (start + 0, 10)
+Highest counter ID seen: c1
 
diff --git a/tests/coverage/attr/impl.cov-map b/tests/coverage/attr/impl.cov-map
@@ -5,6 +5,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Zero) at (prev + 14, 5) to (start + 0, 19)
+Highest counter ID seen: (none)
 
 Function name: <impl::MyStruct>::on_inherit (unused)
 Raw bytes (9): 0x[01, 01, 00, 01, 00, 16, 05, 00, 17]
@@ -13,6 +14,7 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Zero) at (prev + 22, 5) to (start + 0, 23)
+Highest counter ID seen: (none)
 
 Function name: <impl::MyStruct>::on_on (unused)
 Raw bytes (9): 0x[01, 01, 00, 01, 00, 19, 05, 00, 12]
@@ -21,4 +23,5 @@ Number of files: 1
 Number of expressions: 0
 Number of file 0 mappings: 1
 - Code(Zero) at (prev + 25, 5) to (start + 0, 18)
+Highest counter ID seen: (none)