SIL: add var Instruction.mayCallFunction

It checks if arbitrary functions may be called by an instruction.
This can be either directly, e.g. by an `apply` instruction, or indirectly by destroying a value which might have a deinitializer which can call functions.

SwiftCompilerSources/Sources/SIL/Instruction.swift

@@ -143,6 +143,11 @@ public class Instruction : CustomStringConvertible, Hashable {
     return bridged.mayAccessPointer()
   }
 
+  /// True if arbitrary functions may be called by this instruction.
+  /// This can be either directly, e.g. by an `apply` instruction, or indirectly by destroying a value which
+  /// might have a deinitializer which can call functions.
+  public var mayCallFunction: Bool { false }
+
   public final var mayLoadWeakOrUnowned: Bool {
     return bridged.mayLoadWeakOrUnowned()
   }
@@ -331,6 +336,8 @@ final public class StoreInst : Instruction, StoringInstruction {
   public var storeOwnership: StoreOwnership {
     StoreOwnership(rawValue: bridged.StoreInst_getStoreOwnership())!
   }
+
+  public override var mayCallFunction: Bool { storeOwnership == .assign }
 }
 
 final public class StoreWeakInst : Instruction, StoringInstruction { }
@@ -345,6 +352,15 @@ final public class AssignInst : Instruction, StoringInstruction {
   public var assignOwnership: AssignOwnership {
     AssignOwnership(rawValue: bridged.AssignInst_getAssignOwnership())!
   }
+
+  public override var mayCallFunction: Bool {
+    switch assignOwnership {
+    case .unknown, .reassign, .reinitialize:
+      true
+    case .initialize:
+      false
+    }
+  }
 }
 
 final public class AssignOrInitInst : Instruction, StoringInstruction {}
@@ -382,6 +398,7 @@ final public class CopyAddrInst : Instruction, SourceDestAddrInstruction {
     bridged.CopyAddrInst_setIsInitializationOfDest(isInitializationOfDestination)
     context.notifyInstructionChanged(self)
   }
+  public override var mayCallFunction: Bool { !isInitializationOfDestination }
 }
 
 final public class ExplicitCopyAddrInst : Instruction, SourceDestAddrInstruction {
@@ -394,6 +411,7 @@ final public class ExplicitCopyAddrInst : Instruction, SourceDestAddrInstruction
   public var isInitializationOfDestination: Bool {
     bridged.ExplicitCopyAddrInst_isInitializationOfDest()
   }
+  public override var mayCallFunction: Bool { !isInitializationOfDestination }
 }
 
 final public class MarkUninitializedInst : SingleValueInstruction, UnaryInstruction {
@@ -639,10 +657,12 @@ final public class RetainValueAddrInst : RefCountingInst {
 }
 
 final public class ReleaseValueAddrInst : RefCountingInst {
+  public override var mayCallFunction: Bool { true }
 }
 
 final public class StrongReleaseInst : RefCountingInst {
   public var instance: Value { operand.value }
+  public override var mayCallFunction: Bool { true }
 }
 
 final public class UnownedReleaseInst : RefCountingInst {
@@ -651,10 +671,12 @@ final public class UnownedReleaseInst : RefCountingInst {
 
 final public class ReleaseValueInst : RefCountingInst {
   public var value: Value { return operand.value }
+  public override var mayCallFunction: Bool { true }
 }
 
 final public class UnmanagedReleaseValueInst : RefCountingInst {
   public var value: Value { return operand.value }
+  public override var mayCallFunction: Bool { true }
 }
 
 final public class AutoreleaseValueInst : RefCountingInst {}
@@ -667,10 +689,14 @@ final public class DestroyValueInst : Instruction, UnaryInstruction {
   /// end the lifetime of its operand.
   /// Such `destroy_value` instructions are lowered to no-ops.
   public var isDeadEnd: Bool { bridged.DestroyValueInst_isDeadEnd() }
+
+  public override var mayCallFunction: Bool { true }
 }
 
 final public class DestroyAddrInst : Instruction, UnaryInstruction {
   public var destroyedAddress: Value { operand.value }
+
+  public override var mayCallFunction: Bool { true }
 }
 
 final public class EndLifetimeInst : Instruction, UnaryInstruction {}
@@ -762,6 +788,15 @@ final public class BuiltinInst : SingleValueInstruction {
   public var arguments: LazyMapSequence<OperandArray, Value> {
     operands.values
   }
+
+  public override var mayCallFunction: Bool {
+    switch id {
+    case .Once, .OnFastPath, .Destroy, .DestroyArray, .DestroyTaskGroup, .DestroyDefaultActor, .Release:
+      true
+    default:
+      false
+    }
+  }
 }
 
 final public class UpcastInst : SingleValueInstruction, UnaryInstruction {
@@ -1371,6 +1406,8 @@ final public class ApplyInst : SingleValueInstruction, FullApplySite {
   public typealias SpecializationInfo = BridgedGenericSpecializationInformation
 
   public var specializationInfo: SpecializationInfo { bridged.ApplyInst_getSpecializationInfo() }
+
+  public override var mayCallFunction: Bool { true }
 }
 
 final public class FunctionExtractIsolationInst : SingleValueInstruction {}
@@ -1648,7 +1685,12 @@ final public class BeginAccessInst : SingleValueInstruction, UnaryInstruction {
     case read = 1
     case modify = 2
     case `deinit` = 3
+
+    public func conflicts(with other: AccessKind) -> Bool {
+      return self != .read || other != .read
+    }
   }
+
   public var accessKind: AccessKind {
     AccessKind(rawValue: bridged.BeginAccessInst_getAccessKind())!
   }
@@ -1730,11 +1772,15 @@ final public class BeginApplyInst : MultipleValueInstruction, FullApplySite {
 
   public var isNonThrowing: Bool { bridged.BeginApplyInst_getNonThrowing() }
   public var isNonAsync: Bool { bridged.BeginApplyInst_getNonAsync() }
+
+  public override var mayCallFunction: Bool { true }
 }
 
 final public class EndApplyInst : SingleValueInstruction, UnaryInstruction {
   public var token: MultipleValueInstructionResult { operand.value as! MultipleValueInstructionResult }
   public var beginApply: BeginApplyInst { token.parentInstruction as! BeginApplyInst }
+
+  public override var mayCallFunction: Bool { true }
 }
 
 final public class AbortApplyInst : Instruction, UnaryInstruction {
@@ -1931,6 +1977,8 @@ final public class TryApplyInst : TermInst, FullApplySite {
 
   public var isNonAsync: Bool { bridged.TryApplyInst_getNonAsync() }
   public var specializationInfo: ApplyInst.SpecializationInfo { bridged.TryApplyInst_getSpecializationInfo() }
+
+  public override var mayCallFunction: Bool { true }
 }
 
 final public class BranchInst : TermInst {