[CodeGen] Avoid destructing a callee-destructued struct type in a

function if a function delegates to another function.

Fix a bug introduced in r328731, which caused a struct with ObjC __weak
fields that was passed to a function to be destructed twice, once in the
callee function and once in another function the callee function
delegates to. To prevent this, keep track of the callee-destructed
structs passed to a function and disable their cleanups at the point of
the call to the delegated function.

rdar://problem/39194693

Differential Revision: https://reviews.llvm.org/D45382

llvm-svn: 331016

1 files changed, 16 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 392c7b1ded5..d4374ff6e09 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -3063,6 +3063,22 @@ void CodeGenFunction::EmitDelegateCallArg(CallArgList &args,
   } else {
     args.add(convertTempToRValue(local, type, loc), type);
   }
+
+  // Deactivate the cleanup for the callee-destructed param that was pushed.
+  if (hasAggregateEvaluationKind(type) &&
+      getContext().isParamDestroyedInCallee(type)) {
+    EHScopeStack::stable_iterator cleanup =
+        CalleeDestructedParamCleanups.lookup(cast<ParmVarDecl>(param));
+    if (cleanup.isValid()) {
+      // This unreachable is a temporary marker which will be removed later.
+      llvm::Instruction *isActive = Builder.CreateUnreachable();
+      args.addArgCleanupDeactivation(cleanup, isActive);
+    } else
+      // A param cleanup should have been pushed unless we are code-generating
+      // a thunk.
+      assert(CurFuncIsThunk &&
+             "cleanup for callee-destructed param not recorded");
+  }
 }
 
 static bool isProvablyNull(llvm::Value *addr) {