From 2a713729f4183a3f0138194bc8aa986c5a4dea23 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Thu, 11 May 2017 18:58:24 +0000
Subject: [PATCH] PR22877: When constructing an array via a constructor with a
 default argument in list-initialization, run cleanups for the default
 argument after each iteration of the initialization loop.

We previously only ran the destructor for any temporary once, at the end of the
complete loop, rather than once per iteration!

Re-commit of r302750, reverted in r302776.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@302817 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CGExprAgg.cpp                  | 20 ++++++++----
 test/CodeGenCXX/array-default-argument.cpp | 36 ++++++++++++++++++++++
 2 files changed, 50 insertions(+), 6 deletions(-)
 create mode 100644 test/CodeGenCXX/array-default-argument.cpp

diff --git a/lib/CodeGen/CGExprAgg.cpp b/lib/CodeGen/CGExprAgg.cpp
index 49bbb4808e..a05a088f09 100644
--- a/lib/CodeGen/CGExprAgg.cpp
+++ b/lib/CodeGen/CGExprAgg.cpp
@@ -512,12 +512,20 @@ void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
     currentElement->addIncoming(element, entryBB);
 
     // Emit the actual filler expression.
-    LValue elementLV =
-      CGF.MakeAddrLValue(Address(currentElement, elementAlign), elementType);
-    if (filler)
-      EmitInitializationToLValue(filler, elementLV);
-    else
-      EmitNullInitializationToLValue(elementLV);
+    {
+      // C++1z [class.temporary]p5:
+      //   when a default constructor is called to initialize an element of
+      //   an array with no corresponding initializer [...] the destruction of
+      //   every temporary created in a default argument is sequenced before
+      //   the construction of the next array element, if any
+      CodeGenFunction::RunCleanupsScope CleanupsScope(CGF);
+      LValue elementLV =
+        CGF.MakeAddrLValue(Address(currentElement, elementAlign), elementType);
+      if (filler)
+        EmitInitializationToLValue(filler, elementLV);
+      else
+        EmitNullInitializationToLValue(elementLV);
+    }
 
     // Move on to the next element.
     llvm::Value *nextElement =
diff --git a/test/CodeGenCXX/array-default-argument.cpp b/test/CodeGenCXX/array-default-argument.cpp
new file mode 100644
index 0000000000..8376b4f340
--- /dev/null
+++ b/test/CodeGenCXX/array-default-argument.cpp
@@ -0,0 +1,36 @@
+// RUN: %clang_cc1 -emit-llvm -o - %s -triple %itanium_abi_triple | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -o - %s -triple %itanium_abi_triple -fexceptions -fcxx-exceptions | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-EH
+
+struct A {
+  A();
+  ~A();
+};
+
+struct B {
+  B(A = A());
+  ~B();
+};
+
+void f();
+// CHECK-LABEL: define void @_Z1gv()
+void g() {
+  // CHECK: br label %[[LOOP:.*]]
+
+  // [[LOOP]]:
+  // CHECK: {{call|invoke}} {{.*}} @_ZN1AC1Ev([[TEMPORARY:.*]])
+  // CHECK-EH:  unwind label %[[PARTIAL_ARRAY_LPAD:.*]]
+  // CHECK: {{call|invoke}} {{.*}} @_ZN1BC1E1A({{.*}}, [[TEMPORARY]])
+  // CHECK-EH:  unwind label %[[A_AND_PARTIAL_ARRAY_LPAD:.*]]
+  // CHECK: {{call|invoke}} {{.*}} @_ZN1AD1Ev([[TEMPORARY]])
+  // CHECK-EH:  unwind label %[[PARTIAL_ARRAY_LPAD]]
+  // CHECK: getelementptr {{.*}}, i{{[0-9]*}} 1
+  // CHECK: icmp eq
+  // CHECK: br i1 {{.*}} label %[[LOOP]]
+  B b[5];
+
+  // CHECK: {{call|invoke}} void @_Z1fv()
+  f();
+
+  // CHECK-NOT: @_ZN1AD1Ev(
+  // CHECK: {{call|invoke}} {{.*}} @_ZN1BD1Ev(
+}
-- 
2.40.0