Optimizer: add the Builder.insertCleanupAtFunctionExits utility

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/ConstantCapturePropagation.swift

@@ -195,8 +195,7 @@ private func cloneArgument(_ argumentOp: Operand,
   if partialApply.calleeArgumentConventions[calleeArgIdx].isGuaranteed {
     // If the original argument was passed as guaranteed, i.e. is _not_ destroyed in the closure, we have
     // to destroy the cloned argument at function exits.
-    for block in targetFunction.blocks where block.terminator.isFunctionExiting {
-      let builder = Builder(before: block.terminator, context)
+    Builder.insertCleanupAtFunctionExits(of: targetFunction, context) { builder in
       builder.emitDestroy(of: clonedArg)
     }
   }

SwiftCompilerSources/Sources/Optimizer/ModulePasses/StackProtection.swift

@@ -339,13 +339,9 @@ private struct StackProtectionOptimization {
 
     builder.createCopyAddr(from: argument, to: temporary, takeSource: true, initializeDest: true)
 
-    for block in function.blocks {
-      let terminator = block.terminator
-      if terminator.isFunctionExiting {
-        let exitBuilder = Builder(before: terminator, location: terminator.location.asAutoGenerated, context)
-        exitBuilder.createCopyAddr(from: temporary, to: argument, takeSource: true, initializeDest: true)
-        exitBuilder.createDeallocStack(temporary)
-      }
+    Builder.insertCleanupAtFunctionExits(of: function, context) { builder in
+      builder.createCopyAddr(from: temporary, to: argument, takeSource: true, initializeDest: true)
+      builder.createDeallocStack(temporary)
     }
     log("move addr protection in \(function.name): \(argument)")
 

SwiftCompilerSources/Sources/Optimizer/Utilities/OptUtils.swift

@@ -262,6 +262,18 @@ extension Builder {
     }
   }
 
+  static func insertCleanupAtFunctionExits(
+    of function: Function,
+    _ context: some MutatingContext,
+    insert: (Builder) -> ()
+  ) {
+    for exitBlock in function.blocks where exitBlock.terminator.isFunctionExiting {
+      let terminator = exitBlock.terminator
+      let builder = Builder(before: terminator, location: terminator.location.asCleanup, context)
+      insert(builder)
+    }
+  }
+
   func destroyCapturedArgs(for paiOnStack: PartialApplyInst) {
     precondition(paiOnStack.isOnStack, "Function must only be called for `partial_apply`s on stack!")
     self.bridged.destroyCapturedArgs(paiOnStack.bridged)