Merge pull request #81512 from meg-gupta/fixdropdeinitcp

[6.2] Fix InstructionDeleter for drop_deinit instruction

Author: meg-gupta

lib/SILOptimizer/Utils/InstructionDeleter.cpp

@@ -63,6 +63,12 @@ static bool isScopeAffectingInstructionDead(SILInstruction *inst,
     return false;
   }
 
+  // Don't delete dead drop_deinit instruction. They are a marker to eliminate
+  // user-defined deinit and we do not want to lose it.
+  if (isa<DropDeinitInst>(inst)) {
+    return false;
+  }
+
   for (auto result : inst->getResults()) {
     // If inst has any owned move-only value as a result, deleting it may
     // shorten that value's lifetime which is illegal according to language
@@ -268,9 +274,16 @@ void InstructionDeleter::deleteWithUses(SILInstruction *inst, bool fixLifetimes,
       if (fixLifetimes) {
         LoadInst *li = nullptr;
         if (operand.isConsuming()) {
-          SILBuilderWithScope builder(inst);
-          auto *dvi = builder.createDestroyValue(inst->getLoc(), operandValue);
-          getCallbacks().createdNewInst(dvi);
+          if (isa<DropDeinitInst>(operandValue)) {
+            SILBuilderWithScope builder(inst);
+            auto *eli = builder.createEndLifetime(inst->getLoc(), operandValue);
+            getCallbacks().createdNewInst(eli);
+          } else {
+            SILBuilderWithScope builder(inst);
+            auto *dvi =
+                builder.createDestroyValue(inst->getLoc(), operandValue);
+            getCallbacks().createdNewInst(dvi);
+          }
         } else if ((li = dyn_cast<LoadInst>(inst)) &&
                    li->getOwnershipQualifier() ==
                        LoadOwnershipQualifier::Take) {

test/SILOptimizer/drop_deinit_opt.sil

@@ -0,0 +1,47 @@
+// RUN: %target-sil-opt %s -early-inline -mem2reg | %FileCheck %s
+
+import Swift
+import Builtin
+
+struct FileDescriptor : ~Copyable {
+  @_hasStorage private var fd: Int { get set }
+  init(_ fd: Int)
+  deinit
+}
+
+sil hidden [ossa] @fd_close : $@convention(thin) (Int) -> () {
+bb0(%0 : $Int):
+  debug_value %0, let, name "fd", argno 1
+  %2 = tuple ()
+  return %2
+}
+
+// CHECK-LABEL: sil hidden [ossa] @fd_deinit1 :
+// CHECK: drop_deinit
+// CHECK-LABEL: } // end sil function 'fd_deinit1'
+sil hidden [ossa] @fd_deinit1 : $@convention(method) (@owned FileDescriptor) -> () {
+bb0(%0 : @owned $FileDescriptor):
+  %1 = alloc_stack $FileDescriptor, let, name "self", argno 1
+  store %0 to [init] %1
+  %3 = drop_deinit %1
+  %6 = struct_element_addr %3, #FileDescriptor.fd
+  %7 = load [trivial] %6
+  %9 = function_ref @fd_close : $@convention(thin) (Int) -> ()
+  %10 = apply %9(%7) : $@convention(thin) (Int) -> ()
+  dealloc_stack %1
+  %12 = tuple ()
+  return %12
+}
+
+// CHECK-LABEL: sil hidden [ossa] @fd_deinit2 :
+// CHECK: end_lifetime
+// CHECK-LABEL: } // end sil function 'fd_deinit2'
+sil hidden [ossa] @fd_deinit2 : $@convention(method) (@owned FileDescriptor) -> () {
+bb0(%0 : @owned $FileDescriptor):
+  %3 = drop_deinit %0
+  %6 = destructure_struct %3
+  %9 = function_ref @fd_close : $@convention(thin) (Int) -> ()
+  %10 = apply %9(%6) : $@convention(thin) (Int) -> ()
+  %12 = tuple ()
+  return %12
+}