[SwiftCompilerSources] Add assert to Builder.init(after:)

This API is incorrect for terminators. Assert that it isn't used
incorrectly. Later, we should rename it.

Author: atrick

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/LifetimeDependenceInsertion.swift

@@ -116,7 +116,6 @@ private func insertDependencies(for apply: LifetimeDependentApply,
     insertMarkDependencies(value: dependentValue, initializer: nil,
                            bases: bases, builder: builder, context)
   }
-  let builder = Builder(after: apply.applySite, context)
   for resultOper in apply.applySite.indirectResultOperands {
     let accessBase = resultOper.value.accessBase
     guard let (initialAddress, initializingStore) =
@@ -132,11 +131,11 @@ private func insertDependencies(for apply: LifetimeDependentApply,
                                             context) else {
       continue
     }
-    assert(initializingStore == resultOper.instruction,
-           "an indirect result is a store")
-    insertMarkDependencies(value: initialAddress,
-                           initializer: initializingStore, bases: bases,
-                           builder: builder, context)
+    assert(initializingStore == resultOper.instruction, "an indirect result is a store")
+    Builder.insert(after: apply.applySite, context) { builder in
+      insertMarkDependencies(value: initialAddress, initializer: initializingStore, bases: bases, builder: builder,
+                             context)
+    }
   }
 }
 

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/ObjCBridgingOptimization.swift

@@ -232,7 +232,7 @@ private func optimizeNonOptionalBridging(_ apply: ApplyInst,
 private func removeBridgingCodeInPredecessors(of block: BasicBlock, _ context: FunctionPassContext) {
   for pred in block.predecessors {
     let branch = pred.terminator as! BranchInst
-    let builder = Builder(after: branch, context)
+    let builder = Builder(atEndOf: branch.parentBlock, location: branch.location, context)
     builder.createBranch(to: block)
 
     let en = branch.operands[0].value as! EnumInst

SwiftCompilerSources/Sources/Optimizer/PassManager/Context.swift

@@ -492,19 +492,23 @@ extension Builder {
   }
 
   /// Creates a builder which inserts _after_ `insPnt`, using a custom `location`.
+  ///
+  /// TODO: this is usually incorrect for terminator instructions. Instead use
+  /// `Builder.insert(after:location:_:insertFunc)` from OptUtils.swift. Rename this to afterNonTerminator.
   init(after insPnt: Instruction, location: Location, _ context: some MutatingContext) {
     context.verifyIsTransforming(function: insPnt.parentFunction)
-    if let nextInst = insPnt.next {
-      self.init(insertAt: .before(nextInst), location: location,
-                context.notifyInstructionChanged, context._bridged.asNotificationHandler())
-    } else {
-      self.init(insertAt: .atEndOf(insPnt.parentBlock), location: location,
-                context.notifyInstructionChanged, context._bridged.asNotificationHandler())
+    guard let nextInst = insPnt.next else {
+      fatalError("cannot insert an instruction after a block terminator.")
     }
+    self.init(insertAt: .before(nextInst), location: location,
+              context.notifyInstructionChanged, context._bridged.asNotificationHandler())
   }
 
   /// Creates a builder which inserts _after_ `insPnt`, using `insPnt`'s next
   /// non-meta instruction's location.
+  ///
+  /// TODO: this is incorrect for terminator instructions. Instead use `Builder.insert(after:location:_:insertFunc)`
+  /// from OptUtils.swift. Rename this to afterNonTerminator.
   init(after insPnt: Instruction, _ context: some MutatingContext) {
     self.init(after: insPnt, location: insPnt.locationOfNextNonMetaInstruction, context)
   }

SwiftCompilerSources/Sources/Optimizer/Utilities/FunctionSignatureTransforms.swift

@@ -179,7 +179,6 @@ private func createForwardingApply(
                                        isNonThrowing: ai.isNonThrowing,
                                        isNonAsync: ai.isNonAsync,
                                        specializationInfo: ai.specializationInfo)
-    let builder = Builder(after: newApply, context)
     builder.createReturn(of: newApply)
   case let tai as TryApplyInst:
     let normalBlock = thunk.appendNewBlock(context)

SwiftCompilerSources/Sources/Optimizer/Utilities/OptUtils.swift

@@ -163,6 +163,10 @@ extension FullApplySite {
 }
 
 extension Builder {
+  static func insert(after inst: Instruction, _ context: some MutatingContext, insertFunc: (Builder) -> ()) {
+    Builder.insert(after: inst, location: inst.location, context, insertFunc: insertFunc)
+  }
+
   static func insert(after inst: Instruction, location: Location,
                      _ context: some MutatingContext, insertFunc: (Builder) -> ()) {
     if inst is TermInst {