coverage: Use SpanMarker to improve coverage spans for if ! expressions

compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs

@@ -100,6 +100,9 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
 
         let Coverage { kind } = coverage;
         match *kind {
+            // Span markers are only meaningful during MIR instrumentation,
+            // and have no effect during codegen.
+            CoverageKind::SpanMarker => {}
             CoverageKind::CounterIncrement { id } => {
                 func_coverage.mark_counter_id_seen(id);
                 // We need to explicitly drop the `RefMut` before calling into `instrprof_increment`,

compiler/rustc_middle/src/mir/coverage.rs

@@ -76,6 +76,13 @@ impl Debug for CovTerm {
 
 #[derive(Clone, PartialEq, TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
 pub enum CoverageKind {
+    /// Marks a span that might otherwise not be represented in MIR, so that
+    /// coverage instrumentation can associate it with its enclosing block/BCB.
+    ///
+    /// Only used by the `InstrumentCoverage` pass, and has no effect during
+    /// codegen.
+    SpanMarker,
+
     /// Marks the point in MIR control flow represented by a coverage counter.
     ///
     /// This is eventually lowered to `llvm.instrprof.increment` in LLVM IR.
@@ -99,6 +106,7 @@ impl Debug for CoverageKind {
     fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
         use CoverageKind::*;
         match self {
+            SpanMarker => write!(fmt, "SpanMarker"),
             CounterIncrement { id } => write!(fmt, "CounterIncrement({:?})", id.index()),
             ExpressionUsed { id } => write!(fmt, "ExpressionUsed({:?})", id.index()),
         }

compiler/rustc_mir_build/src/build/cfg.rs

@@ -101,6 +101,19 @@ impl<'tcx> CFG<'tcx> {
         self.push(block, stmt);
     }
 
+    /// Adds a dummy statement whose only role is to associate a span with its
+    /// enclosing block for the purposes of coverage instrumentation.
+    ///
+    /// This results in more accurate coverage reports for certain kinds of
+    /// syntax (e.g. `continue` or `if !`) that would otherwise not appear in MIR.
+    pub(crate) fn push_coverage_span_marker(&mut self, block: BasicBlock, source_info: SourceInfo) {
+        let kind = StatementKind::Coverage(Box::new(Coverage {
+            kind: coverage::CoverageKind::SpanMarker,
+        }));
+        let stmt = Statement { source_info, kind };
+        self.push(block, stmt);
+    }
+
     pub(crate) fn terminate(
         &mut self,
         block: BasicBlock,

compiler/rustc_mir_build/src/build/matches/mod.rs

@@ -90,6 +90,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 let local_scope = this.local_scope();
                 let (success_block, failure_block) =
                     this.in_if_then_scope(local_scope, expr_span, |this| {
+                        // Help out coverage instrumentation by injecting a dummy statement with
+                        // the original condition's span (including `!`). This fixes #115468.
+                        if this.tcx.sess.instrument_coverage() {
+                            this.cfg.push_coverage_span_marker(block, this.source_info(expr_span));
+                        }
                         this.then_else_break(
                             block,
                             &this.thir[arg],

compiler/rustc_mir_build/src/build/scope.rs

@@ -90,7 +90,6 @@ use rustc_index::{IndexSlice, IndexVec};
 use rustc_middle::middle::region;
 use rustc_middle::mir::*;
 use rustc_middle::thir::{Expr, LintLevel};
-use rustc_middle::ty::Ty;
 use rustc_session::lint::Level;
 use rustc_span::{Span, DUMMY_SP};
 
@@ -660,14 +659,15 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             (None, Some(_)) => {
                 panic!("`return`, `become` and `break` with value and must have a destination")
             }
-            (None, None) if self.tcx.sess.instrument_coverage() => {
-                // Unlike `break` and `return`, which push an `Assign` statement to MIR, from which
-                // a Coverage code region can be generated, `continue` needs no `Assign`; but
-                // without one, the `InstrumentCoverage` MIR pass cannot generate a code region for
-                // `continue`. Coverage will be missing unless we add a dummy `Assign` to MIR.
-                self.add_dummy_assignment(span, block, source_info);
+            (None, None) => {
+                if self.tcx.sess.instrument_coverage() {
+                    // Normally we wouldn't build any MIR in this case, but that makes it
+                    // harder for coverage instrumentation to extract a relevant span for
+                    // `continue` expressions. So here we inject a dummy statement with the
+                    // desired span.
+                    self.cfg.push_coverage_span_marker(block, source_info);
+                }
             }
-            (None, None) => {}
         }
 
         let region_scope = self.scopes.breakable_scopes[break_index].region_scope;
@@ -723,14 +723,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         self.cfg.terminate(block, source_info, TerminatorKind::UnwindResume);
     }
 
-    // Add a dummy `Assign` statement to the CFG, with the span for the source code's `continue`
-    // statement.
-    fn add_dummy_assignment(&mut self, span: Span, block: BasicBlock, source_info: SourceInfo) {
-        let local_decl = LocalDecl::new(Ty::new_unit(self.tcx), span);
-        let temp_place = Place::from(self.local_decls.push(local_decl));
-        self.cfg.push_assign_unit(block, source_info, temp_place, self.tcx);
-    }
-
     fn leave_top_scope(&mut self, block: BasicBlock) -> BasicBlock {
         // If we are emitting a `drop` statement, we need to have the cached
         // diverge cleanup pads ready in case that drop panics.

compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs

@@ -92,13 +92,13 @@ fn is_closure(statement: &Statement<'_>) -> bool {
 /// If the MIR `Statement` has a span contributive to computing coverage spans,
 /// return it; otherwise return `None`.
 fn filtered_statement_span(statement: &Statement<'_>) -> Option<Span> {
+    use mir::coverage::CoverageKind;
+
     match statement.kind {
         // These statements have spans that are often outside the scope of the executed source code
         // for their parent `BasicBlock`.
         StatementKind::StorageLive(_)
         | StatementKind::StorageDead(_)
-        // Coverage should not be encountered, but don't inject coverage coverage
-        | StatementKind::Coverage(_)
         // Ignore `ConstEvalCounter`s
         | StatementKind::ConstEvalCounter
         // Ignore `Nop`s
@@ -122,9 +122,13 @@ fn filtered_statement_span(statement: &Statement<'_>) -> Option<Span> {
         // If and when the Issue is resolved, remove this special case match pattern:
         StatementKind::FakeRead(box (FakeReadCause::ForGuardBinding, _)) => None,
 
-        // Retain spans from all other statements
+        // Retain spans from most other statements.
         StatementKind::FakeRead(box (_, _)) // Not including `ForGuardBinding`
         | StatementKind::Intrinsic(..)
+        | StatementKind::Coverage(box mir::Coverage {
+            // The purpose of `SpanMarker` is to be matched and accepted here.
+            kind: CoverageKind::SpanMarker
+        })
         | StatementKind::Assign(_)
         | StatementKind::SetDiscriminant { .. }
         | StatementKind::Deinit(..)
@@ -133,6 +137,11 @@ fn filtered_statement_span(statement: &Statement<'_>) -> Option<Span> {
         | StatementKind::AscribeUserType(_, _) => {
             Some(statement.source_info.span)
         }
+
+        StatementKind::Coverage(box mir::Coverage {
+            // These coverage statements should not exist prior to coverage instrumentation.
+            kind: CoverageKind::CounterIncrement { .. } | CoverageKind::ExpressionUsed { .. }
+        }) => bug!("Unexpected coverage statement found during coverage instrumentation: {statement:?}"),
     }
 }
 

tests/coverage/if_not.cov-map

@@ -0,0 +1,39 @@
+Function name: if_not::if_not
+Raw bytes (86): 0x[01, 01, 10, 01, 05, 05, 02, 3f, 09, 05, 02, 09, 3a, 3f, 09, 05, 02, 37, 0d, 09, 3a, 3f, 09, 05, 02, 0d, 32, 37, 0d, 09, 3a, 3f, 09, 05, 02, 0a, 01, 04, 01, 03, 0d, 02, 04, 05, 02, 06, 05, 02, 06, 00, 07, 3f, 03, 09, 01, 0d, 3a, 02, 05, 02, 06, 09, 02, 06, 00, 07, 37, 03, 09, 01, 0d, 32, 02, 05, 02, 06, 0d, 02, 0c, 02, 06, 2f, 03, 01, 00, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 16
+- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 1 operands: lhs = Counter(1), rhs = Expression(0, Sub)
+- expression 2 operands: lhs = Expression(15, Add), rhs = Counter(2)
+- expression 3 operands: lhs = Counter(1), rhs = Expression(0, Sub)
+- expression 4 operands: lhs = Counter(2), rhs = Expression(14, Sub)
+- expression 5 operands: lhs = Expression(15, Add), rhs = Counter(2)
+- expression 6 operands: lhs = Counter(1), rhs = Expression(0, Sub)
+- expression 7 operands: lhs = Expression(13, Add), rhs = Counter(3)
+- expression 8 operands: lhs = Counter(2), rhs = Expression(14, Sub)
+- expression 9 operands: lhs = Expression(15, Add), rhs = Counter(2)
+- expression 10 operands: lhs = Counter(1), rhs = Expression(0, Sub)
+- expression 11 operands: lhs = Counter(3), rhs = Expression(12, Sub)
+- expression 12 operands: lhs = Expression(13, Add), rhs = Counter(3)
+- expression 13 operands: lhs = Counter(2), rhs = Expression(14, Sub)
+- expression 14 operands: lhs = Expression(15, Add), rhs = Counter(2)
+- expression 15 operands: lhs = Counter(1), rhs = Expression(0, Sub)
+Number of file 0 mappings: 10
+- Code(Counter(0)) at (prev + 4, 1) to (start + 3, 13)
+- Code(Expression(0, Sub)) at (prev + 4, 5) to (start + 2, 6)
+    = (c0 - c1)
+- Code(Counter(1)) at (prev + 2, 6) to (start + 0, 7)
+- Code(Expression(15, Add)) at (prev + 3, 9) to (start + 1, 13)
+    = (c1 + (c0 - c1))
+- Code(Expression(14, Sub)) at (prev + 2, 5) to (start + 2, 6)
+    = ((c1 + (c0 - c1)) - c2)
+- Code(Counter(2)) at (prev + 2, 6) to (start + 0, 7)
+- Code(Expression(13, Add)) at (prev + 3, 9) to (start + 1, 13)
+    = (c2 + ((c1 + (c0 - c1)) - c2))
+- Code(Expression(12, Sub)) at (prev + 2, 5) to (start + 2, 6)
+    = ((c2 + ((c1 + (c0 - c1)) - c2)) - c3)
+- Code(Counter(3)) at (prev + 2, 12) to (start + 2, 6)
+- Code(Expression(11, Add)) at (prev + 3, 1) to (start + 0, 2)
+    = (c3 + ((c2 + ((c1 + (c0 - c1)) - c2)) - c3))
+

tests/coverage/if_not.coverage

@@ -0,0 +1,38 @@
+   LL|       |#![feature(coverage_attribute)]
+   LL|       |// edition: 2021
+   LL|       |
+   LL|     12|fn if_not(cond: bool) {
+   LL|     12|    if
+   LL|     12|        !
+   LL|     12|        cond
+   LL|      4|    {
+   LL|      4|        println!("cond was false");
+   LL|      8|    }
+   LL|       |
+   LL|       |    if
+   LL|     12|        !
+   LL|     12|        cond
+   LL|      4|    {
+   LL|      4|        println!("cond was false");
+   LL|      8|    }
+   LL|       |
+   LL|       |    if
+   LL|     12|        !
+   LL|     12|        cond
+   LL|      4|    {
+   LL|      4|        println!("cond was false");
+   LL|      8|    } else {
+   LL|      8|        println!("cond was true");
+   LL|      8|    }
+   LL|     12|}
+   LL|       |
+   LL|       |#[coverage(off)]
+   LL|       |fn main() {
+   LL|       |    for _ in 0..8 {
+   LL|       |        if_not(std::hint::black_box(true));
+   LL|       |    }
+   LL|       |    for _ in 0..4 {
+   LL|       |        if_not(std::hint::black_box(false));
+   LL|       |    }
+   LL|       |}
+

tests/coverage/if_not.rs

@@ -0,0 +1,37 @@
+#![feature(coverage_attribute)]
+// edition: 2021
+
+fn if_not(cond: bool) {
+    if
+        !
+        cond
+    {
+        println!("cond was false");
+    }
+
+    if
+        !
+        cond
+    {
+        println!("cond was false");
+    }
+
+    if
+        !
+        cond
+    {
+        println!("cond was false");
+    } else {
+        println!("cond was true");
+    }
+}
+
+#[coverage(off)]
+fn main() {
+    for _ in 0..8 {
+        if_not(std::hint::black_box(true));
+    }
+    for _ in 0..4 {
+        if_not(std::hint::black_box(false));
+    }
+}

tests/coverage/lazy_boolean.cov-map

@@ -1,5 +1,5 @@
 Function name: lazy_boolean::main
-Raw bytes (636): 0x[01, 01, a4, 01, 01, 05, 09, 8a, 05, 8f, 05, 09, 05, 02, 05, 02, 8f, 05, 09, 05, 02, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 09, 8a, 05, 8f, 05, 09, 05, 02, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, e7, 04, 1d, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 1d, e2, 04, e7, 04, 1d, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, df, 04, 21, 1d, e2, 04, e7, 04, 1d, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 21, da, 04, df, 04, 21, 1d, e2, 04, e7, 04, 1d, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, d7, 04, 25, 21, da, 04, df, 04, 21, 1d, e2, 04, e7, 04, 1d, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 25, d2, 04, d7, 04, 25, 21, da, 04, df, 04, 21, 1d, e2, 04, e7, 04, 1d, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 1c, 01, 03, 01, 07, 0f, 05, 07, 10, 04, 06, 02, 04, 06, 00, 07, 87, 05, 02, 09, 00, 11, 8f, 05, 02, 0d, 00, 12, 8a, 05, 02, 0d, 00, 12, ff, 04, 03, 09, 00, 11, 87, 05, 02, 0d, 00, 12, 82, 05, 02, 0d, 00, 12, f7, 04, 02, 09, 00, 11, ff, 04, 00, 14, 00, 19, 11, 00, 1d, 00, 22, ef, 04, 01, 09, 00, 11, f7, 04, 00, 14, 00, 19, 15, 00, 1d, 00, 22, ef, 04, 04, 09, 00, 10, ea, 04, 01, 05, 03, 06, 19, 03, 06, 00, 07, e7, 04, 03, 09, 00, 10, 1d, 01, 05, 03, 06, e2, 04, 05, 05, 03, 06, df, 04, 05, 09, 00, 10, da, 04, 00, 11, 02, 06, 21, 02, 06, 00, 07, d7, 04, 02, 08, 00, 0f, 25, 00, 10, 02, 06, d2, 04, 02, 0c, 02, 06, cf, 04, 03, 01, 00, 02]
+Raw bytes (636): 0x[01, 01, a4, 01, 01, 05, 09, 8a, 05, 8f, 05, 09, 05, 02, 05, 02, 8f, 05, 09, 05, 02, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 09, 8a, 05, 8f, 05, 09, 05, 02, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, e7, 04, 1d, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 1d, e2, 04, e7, 04, 1d, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, df, 04, 21, 1d, e2, 04, e7, 04, 1d, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 21, da, 04, df, 04, 21, 1d, e2, 04, e7, 04, 1d, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, d7, 04, 25, 21, da, 04, df, 04, 21, 1d, e2, 04, e7, 04, 1d, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 25, d2, 04, d7, 04, 25, 21, da, 04, df, 04, 21, 1d, e2, 04, e7, 04, 1d, 19, ea, 04, ef, 04, 19, 15, f2, 04, f7, 04, 15, 11, fa, 04, ff, 04, 11, 0d, 82, 05, 87, 05, 0d, 09, 8a, 05, 8f, 05, 09, 05, 02, 1c, 01, 03, 01, 07, 0f, 05, 07, 10, 04, 06, 02, 04, 06, 00, 07, 87, 05, 02, 09, 00, 11, 8f, 05, 02, 0d, 00, 12, 8a, 05, 02, 0d, 00, 12, ff, 04, 03, 09, 00, 11, 87, 05, 02, 0d, 00, 12, 82, 05, 02, 0d, 00, 12, f7, 04, 02, 09, 00, 11, ff, 04, 00, 14, 00, 19, 11, 00, 1d, 00, 22, ef, 04, 01, 09, 00, 11, f7, 04, 00, 14, 00, 19, 15, 00, 1d, 00, 22, ef, 04, 03, 09, 01, 10, ea, 04, 02, 05, 03, 06, 19, 03, 06, 00, 07, e7, 04, 03, 09, 00, 10, 1d, 01, 05, 03, 06, e2, 04, 05, 05, 03, 06, df, 04, 05, 08, 00, 10, da, 04, 00, 11, 02, 06, 21, 02, 06, 00, 07, d7, 04, 02, 08, 00, 0f, 25, 00, 10, 02, 06, d2, 04, 02, 0c, 02, 06, cf, 04, 03, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 164
@@ -194,17 +194,17 @@ Number of file 0 mappings: 28
 - Code(Expression(157, Add)) at (prev + 0, 20) to (start + 0, 25)
     = (c4 + ((c3 + ((c2 + ((c1 + (c0 - c1)) - c2)) - c3)) - c4))
 - Code(Counter(5)) at (prev + 0, 29) to (start + 0, 34)
-- Code(Expression(155, Add)) at (prev + 4, 9) to (start + 0, 16)
+- Code(Expression(155, Add)) at (prev + 3, 9) to (start + 1, 16)
     = (c5 + ((c4 + ((c3 + ((c2 + ((c1 + (c0 - c1)) - c2)) - c3)) - c4)) - c5))
-- Code(Expression(154, Sub)) at (prev + 1, 5) to (start + 3, 6)
+- Code(Expression(154, Sub)) at (prev + 2, 5) to (start + 3, 6)
     = ((c5 + ((c4 + ((c3 + ((c2 + ((c1 + (c0 - c1)) - c2)) - c3)) - c4)) - c5)) - c6)
 - Code(Counter(6)) at (prev + 3, 6) to (start + 0, 7)
 - Code(Expression(153, Add)) at (prev + 3, 9) to (start + 0, 16)
     = (c6 + ((c5 + ((c4 + ((c3 + ((c2 + ((c1 + (c0 - c1)) - c2)) - c3)) - c4)) - c5)) - c6))
 - Code(Counter(7)) at (prev + 1, 5) to (start + 3, 6)
 - Code(Expression(152, Sub)) at (prev + 5, 5) to (start + 3, 6)
     = ((c6 + ((c5 + ((c4 + ((c3 + ((c2 + ((c1 + (c0 - c1)) - c2)) - c3)) - c4)) - c5)) - c6)) - c7)
-- Code(Expression(151, Add)) at (prev + 5, 9) to (start + 0, 16)
+- Code(Expression(151, Add)) at (prev + 5, 8) to (start + 0, 16)
     = (c7 + ((c6 + ((c5 + ((c4 + ((c3 + ((c2 + ((c1 + (c0 - c1)) - c2)) - c3)) - c4)) - c5)) - c6)) - c7))
 - Code(Expression(150, Sub)) at (prev + 0, 17) to (start + 2, 6)
     = ((c7 + ((c6 + ((c5 + ((c4 + ((c3 + ((c2 + ((c1 + (c0 - c1)) - c2)) - c3)) - c4)) - c5)) - c6)) - c7)) - c8)

tests/coverage/lazy_boolean.coverage

@@ -32,7 +32,7 @@
                                           ^0
    LL|       |
    LL|       |    if
-   LL|       |        !
+   LL|      1|        !
    LL|      1|        is_true
    LL|      0|    {
    LL|      0|        a = 2