Merge pull request #71149 from eeckstein/fix-stack-promotion

StackPromotion: prevent resilient classes from being stack promoted.

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/StackPromotion.swift

@@ -68,6 +68,12 @@ private func tryPromoteAlloc(_ allocRef: AllocRefInstBase,
     return false
   }
 
+  // Usually resilient classes cannot be promoted anyway, because their initializers are
+  // not visible and let the object appear to escape.
+  if allocRef.type.nominal.isResilient(in: allocRef.parentFunction) {
+    return false
+  }
+
   // The most important check: does the object escape the current function?
   if allocRef.isEscaping(context) {
     return false

test/SILOptimizer/resilience_and_stack_promotion.sil

@@ -0,0 +1,39 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend -parse-as-library -emit-module -o %t/Module.swiftmodule -module-name=Module %S/Inputs/public_class.swift -O
+// RUN: %target-swift-frontend -parse-as-library -emit-module -o %t/Resilient.swiftmodule -module-name=Resilient %S/Inputs/public_class.swift -O -enable-library-evolution
+
+// RUN: %target-sil-opt -stack-promotion -I %t %s | %FileCheck %s
+
+// REQUIRES: swift_in_compiler
+
+sil_stage canonical
+
+import Builtin
+import Swift
+import SwiftShims
+
+import Module
+import Resilient
+
+// CHECK-LABEL: sil @promote_non_resilient :
+// CHECK:         alloc_ref [stack] $Base
+// CHECK:       } // end sil function 'promote_non_resilient'
+sil @promote_non_resilient : $@convention(thin) () -> () {
+bb0:
+  %0 = alloc_ref $Module.Base
+  strong_release %0 : $Module.Base
+  %2 = tuple ()
+  return %2 : $()
+}
+
+// CHECK-LABEL: sil @dont_promote_resilient :
+// CHECK:         alloc_ref $Base
+// CHECK:       } // end sil function 'dont_promote_resilient'
+sil @dont_promote_resilient : $@convention(thin) () -> () {
+bb0:
+  %0 = alloc_ref $Resilient.Base
+  strong_release %0 : $Resilient.Base
+  %2 = tuple ()
+  return %2 : $()
+}