Rust coverage before splitting instrument_coverage.rs

compiler/rustc_middle/src/mir/coverage.rs

@@ -7,6 +7,10 @@ use std::cmp::Ord;
 use std::fmt::{self, Debug, Formatter};
 
 rustc_index::newtype_index! {
+    /// An ExpressionOperandId value is assigned directly from either a
+    /// CounterValueReference.as_u32() (which ascend from 1) or an ExpressionOperandId.as_u32()
+    /// (which _*descend*_ from u32::MAX). Id value `0` (zero) represents a virtual counter with a
+    /// constant value of `0`.
     pub struct ExpressionOperandId {
         derive [HashStable]
         DEBUG_FORMAT = "ExpressionOperandId({})",
@@ -42,6 +46,20 @@ impl CounterValueReference {
 }
 
 rustc_index::newtype_index! {
+    /// InjectedExpressionId.as_u32() converts to ExpressionOperandId.as_u32()
+    ///
+    /// Values descend from u32::MAX.
+    pub struct InjectedExpressionId {
+        derive [HashStable]
+        DEBUG_FORMAT = "InjectedExpressionId({})",
+        MAX = 0xFFFF_FFFF,
+    }
+}
+
+rustc_index::newtype_index! {
+    /// InjectedExpressionIndex.as_u32() translates to u32::MAX - ExpressionOperandId.as_u32()
+    ///
+    /// Values ascend from 0.
     pub struct InjectedExpressionIndex {
         derive [HashStable]
         DEBUG_FORMAT = "InjectedExpressionIndex({})",
@@ -50,6 +68,9 @@ rustc_index::newtype_index! {
 }
 
 rustc_index::newtype_index! {
+    /// MappedExpressionIndex values ascend from zero, and are recalculated indexes based on their
+    /// array position in the LLVM coverage map "Expressions" array, which is assembled during the
+    /// "mapgen" process. They cannot be computed algorithmically, from the other `newtype_index`s.
     pub struct MappedExpressionIndex {
         derive [HashStable]
         DEBUG_FORMAT = "MappedExpressionIndex({})",
@@ -64,21 +85,35 @@ impl From<CounterValueReference> for ExpressionOperandId {
     }
 }
 
-impl From<InjectedExpressionIndex> for ExpressionOperandId {
+impl From<&mut CounterValueReference> for ExpressionOperandId {
     #[inline]
-    fn from(v: InjectedExpressionIndex) -> ExpressionOperandId {
+    fn from(v: &mut CounterValueReference) -> ExpressionOperandId {
         ExpressionOperandId::from(v.as_u32())
     }
 }
 
-#[derive(Clone, Debug, PartialEq, TyEncodable, TyDecodable, HashStable, TypeFoldable)]
+impl From<InjectedExpressionId> for ExpressionOperandId {
+    #[inline]
+    fn from(v: InjectedExpressionId) -> ExpressionOperandId {
+        ExpressionOperandId::from(v.as_u32())
+    }
+}
+
+impl From<&mut InjectedExpressionId> for ExpressionOperandId {
+    #[inline]
+    fn from(v: &mut InjectedExpressionId) -> ExpressionOperandId {
+        ExpressionOperandId::from(v.as_u32())
+    }
+}
+
+#[derive(Clone, PartialEq, TyEncodable, TyDecodable, HashStable, TypeFoldable)]
 pub enum CoverageKind {
     Counter {
         function_source_hash: u64,
         id: CounterValueReference,
     },
     Expression {
-        id: InjectedExpressionIndex,
+        id: InjectedExpressionId,
         lhs: ExpressionOperandId,
         op: Op,
         rhs: ExpressionOperandId,
@@ -88,12 +123,47 @@ pub enum CoverageKind {
 
 impl CoverageKind {
     pub fn as_operand_id(&self) -> ExpressionOperandId {
+        use CoverageKind::*;
         match *self {
-            CoverageKind::Counter { id, .. } => ExpressionOperandId::from(id),
-            CoverageKind::Expression { id, .. } => ExpressionOperandId::from(id),
-            CoverageKind::Unreachable => {
-                bug!("Unreachable coverage cannot be part of an expression")
-            }
+            Counter { id, .. } => ExpressionOperandId::from(id),
+            Expression { id, .. } => ExpressionOperandId::from(id),
+            Unreachable => bug!("Unreachable coverage cannot be part of an expression"),
+        }
+    }
+
+    pub fn is_counter(&self) -> bool {
+        match self {
+            Self::Counter { .. } => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_expression(&self) -> bool {
+        match self {
+            Self::Expression { .. } => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_unreachable(&self) -> bool {
+        *self == Self::Unreachable
+    }
+}
+
+impl Debug for CoverageKind {
+    fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
+        use CoverageKind::*;
+        match self {
+            Counter { id, .. } => write!(fmt, "Counter({:?})", id.index()),
+            Expression { id, lhs, op, rhs } => write!(
+                fmt,
+                "Expression({:?}) = {} {} {}",
+                id.index(),
+                lhs.index(),
+                if *op == Op::Add { "+" } else { "-" },
+                rhs.index(),
+            ),
+            Unreachable => write!(fmt, "Unreachable"),
         }
     }
 }