SIL: rename protocol BorrowIntroducingInstruction -> BeginBorrowInstruction

to match with `BeginBorrowValue`

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/Analysis/AliasAnalysis.swift

@@ -358,7 +358,7 @@ struct AliasAnalysis {
       return defaultEffects(of: endBorrow, on: memLoc)
     case .box, .class, .tail:
       // Check if the memLoc is "derived" from the begin_borrow, i.e. is an interior pointer.
-      var walker = FindBeginBorrowWalker(beginBorrow: endBorrow.borrow as! BorrowIntroducingInstruction)
+      var walker = FindBeginBorrowWalker(beginBorrow: endBorrow.borrow as! BeginBorrowInstruction)
       return walker.visitAccessStorageRoots(of: accessPath) ? .noEffects : .worstEffects
     }
   }
@@ -704,7 +704,7 @@ private enum ImmutableScope {
 }
 
 private struct FindBeginBorrowWalker : ValueUseDefWalker {
-  let beginBorrow: BorrowIntroducingInstruction
+  let beginBorrow: BeginBorrowInstruction
   var walkUpCache = WalkerCache<Path>()
 
   mutating func walkUp(value: Value, path: SmallProjectionPath) -> WalkResult {

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/LetPropertyLowering.swift

@@ -136,7 +136,7 @@ private func constructLetInitRegion(
   // root-class initializer).
   initRegion.insert(markUninitialized)
 
-  var borrows = Stack<BorrowIntroducingInstruction>(context)
+  var borrows = Stack<BeginBorrowInstruction>(context)
   defer { borrows.deinitialize() }
 
   for inst in markUninitialized.parentFunction.instructions {

SwiftCompilerSources/Sources/Optimizer/Utilities/OptUtils.swift

@@ -826,7 +826,7 @@ extension GlobalVariable {
 
 extension InstructionRange {
   /// Adds the instruction range of a borrow-scope by transitively visiting all (potential) re-borrows.
-  mutating func insert(borrowScopeOf borrow: BorrowIntroducingInstruction, _ context: some Context) {
+  mutating func insert(borrowScopeOf borrow: BeginBorrowInstruction, _ context: some Context) {
     var worklist = ValueWorklist(context)
     defer { worklist.deinitialize() }
 

SwiftCompilerSources/Sources/SIL/Instruction.swift

@@ -1169,7 +1169,7 @@ final public class BridgeObjectToRefInst : SingleValueInstruction, UnaryInstruct
 
 final public class BridgeObjectToWordInst : SingleValueInstruction, UnaryInstruction {}
 
-final public class BorrowedFromInst : SingleValueInstruction, BorrowIntroducingInstruction {
+final public class BorrowedFromInst : SingleValueInstruction, BeginBorrowInstruction {
   public var borrowedValue: Value { operands[0].value }
   public var borrowedPhi: Phi { Phi(borrowedValue)! }
   public var enclosingOperands: OperandArray {
@@ -1431,21 +1431,22 @@ extension Instruction {
   }
 }
 
-/// Instructions beginning a borrow-scope which must be ended by `end_borrow`.
-public protocol BorrowIntroducingInstruction : SingleValueInstruction, ScopedInstruction {
+/// Single-value instructions beginning a borrow-scope which end with an `end_borrow` or a branch to a re-borrow phi.
+/// See also `BeginBorrowValue` which represents all kind of `Value`s which begin a borrow scope.
+public protocol BeginBorrowInstruction : SingleValueInstruction, ScopedInstruction {
 }
 
 final public class EndBorrowInst : Instruction, UnaryInstruction {
   public var borrow: Value { operand.value }
 }
 
-extension BorrowIntroducingInstruction {
+extension BeginBorrowInstruction {
   public var endOperands: LazyFilterSequence<UseList> {
     return self.uses.lazy.filter { $0.instruction is EndBorrowInst }
   }
 }
 
-final public class BeginBorrowInst : SingleValueInstruction, UnaryInstruction, BorrowIntroducingInstruction {
+final public class BeginBorrowInst : SingleValueInstruction, UnaryInstruction, BeginBorrowInstruction {
   public var borrowedValue: Value { operand.value }
 
   public override var isLexical: Bool { bridged.BeginBorrow_isLexical() }
@@ -1457,7 +1458,7 @@ final public class BeginBorrowInst : SingleValueInstruction, UnaryInstruction, B
   }
 }
 
-final public class LoadBorrowInst : SingleValueInstruction, LoadInstruction, BorrowIntroducingInstruction {
+final public class LoadBorrowInst : SingleValueInstruction, LoadInstruction, BeginBorrowInstruction {
 
   // True if the invariants on `load_borrow` have not been checked and should not be strictly enforced.
   //
@@ -1467,7 +1468,7 @@ final public class LoadBorrowInst : SingleValueInstruction, LoadInstruction, Bor
   public var isUnchecked: Bool { bridged.LoadBorrowInst_isUnchecked() }
 }
 
-final public class StoreBorrowInst : SingleValueInstruction, StoringInstruction, BorrowIntroducingInstruction {
+final public class StoreBorrowInst : SingleValueInstruction, StoringInstruction, BeginBorrowInstruction {
   public var allocStack: AllocStackInst {
     var dest = destination
     if let mark = dest as? MarkUnresolvedNonCopyableValueInst {