2 files changed, 185 insertions, 0 deletions
diff --git a/clang/test/CodeGenCXX/stack-reuse-miscompile.cpp b/clang/test/CodeGenCXX/stack-reuse-miscompile.cpp
new file mode 100644
index 00000000000..e6b9cbe3365
--- /dev/null
+++ b/clang/test/CodeGenCXX/stack-reuse-miscompile.cpp
@@ -0,0 +1,39 @@
+// RUN: %clang -S -emit-llvm -O1 -mllvm -disable-llvm-optzns -S %s -o - | FileCheck %s
+
+// This test should not to generate llvm.lifetime.start/llvm.lifetime.end for
+// f function because all temporary objects in this function are used for the
+// final result
+
+class S {
+  char *ptr;
+  unsigned int len;
+};
+
+class T {
+  S left;
+  S right;
+
+public:
+  T(const char s[]);
+  T(S);
+
+  T concat(const T &Suffix) const;
+  const char * str() const;
+};
+
+const char * f(S s)
+{
+// CHECK: %1 = alloca %class.T, align 4
+// CHECK: %2 = alloca %class.T, align 4
+// CHECK: %3 = alloca %class.S, align 4
+// CHECK: %4 = alloca %class.T, align 4
+// CHECK: %5 = call x86_thiscallcc %class.T* @"\01??0T@@QAE@QBD@Z"
+// CHECK: %6 = bitcast %class.S* %3 to i8*
+// CHECK: %7 = bitcast %class.S* %s to i8*
+// CHECK: call void @llvm.memcpy.p0i8.p0i8.i32
+// CHECK: %8 = call x86_thiscallcc %class.T* @"\01??0T@@QAE@VS@@@Z"
+// CHECK: call x86_thiscallcc void @"\01?concat@T@@QBE?AV1@ABV1@@Z"
+// CHECK: %9 = call x86_thiscallcc i8* @"\01?str@T@@QBEPBDXZ"(%class.T* %4)
+
+  return T("[").concat(T(s)).str();
+}
diff --git a/clang/test/CodeGenCXX/stack-reuse.cpp b/clang/test/CodeGenCXX/stack-reuse.cpp
new file mode 100644
index 00000000000..ef73d1a5387
--- /dev/null
+++ b/clang/test/CodeGenCXX/stack-reuse.cpp
@@ -0,0 +1,146 @@
+// RUN: %clang -target armv7l-unknown-linux-gnueabihf -S %s -o - -emit-llvm -O1 -disable-llvm-optzns | FileCheck %s
+
+// Stack should be reused when possible, no need to allocate two separate slots
+// if they have disjoint lifetime.
+
+// Sizes of objects are related to previously existed threshold of 32.  In case
+// of S_large stack size is rounded to 40 bytes.
+
+// 32B
+struct S_small {
+  int a[8];
+};
+
+// 36B
+struct S_large {
+  int a[9];
+};
+
+// Helper class for lifetime scope absence testing
+struct Combiner {
+  S_large a, b;
+
+  Combiner(S_large);
+  Combiner f();  
+};
+
+extern S_small foo_small();
+extern S_large foo_large();
+extern void bar_small(S_small*);
+extern void bar_large(S_large*);
+
+// Prevent mangling of function names.
+extern "C" {
+
+void small_rvoed_unnamed_temporary_object() {
+// CHECK-LABEL: define void @small_rvoed_unnamed_temporary_object
+// CHECK: call void @llvm.lifetime.start
+// CHECK: call void @_Z9foo_smallv
+// CHECK: call void @llvm.lifetime.end
+// CHECK: call void @llvm.lifetime.start
+// CHECK: call void @_Z9foo_smallv
+// CHECK: call void @llvm.lifetime.end
+
+  foo_small();
+  foo_small();
+}
+
+void large_rvoed_unnamed_temporary_object() {
+// CHECK-LABEL: define void @large_rvoed_unnamed_temporary_object
+// CHECK: call void @llvm.lifetime.start
+// CHECK: call void @_Z9foo_largev
+// CHECK: call void @llvm.lifetime.end
+// CHECK: call void @llvm.lifetime.start
+// CHECK: call void @_Z9foo_largev
+// CHECK: call void @llvm.lifetime.end
+
+  foo_large();
+  foo_large();
+}
+
+void small_rvoed_named_temporary_object() {
+// CHECK-LABEL: define void @small_rvoed_named_temporary_object
+// CHECK: call void @llvm.lifetime.start
+// CHECK: call void @_Z9foo_smallv
+// CHECK: call void @llvm.lifetime.end
+// CHECK: call void @llvm.lifetime.start
+// CHECK: call void @_Z9foo_smallv
+// CHECK: call void @llvm.lifetime.end
+
+  {
+    S_small s = foo_small();
+  }
+  {
+    S_small s = foo_small();
+  }
+}
+
+void large_rvoed_named_temporary_object() {
+// CHECK-LABEL: define void @large_rvoed_named_temporary_object
+// CHECK: call void @llvm.lifetime.start
+// CHECK: call void @_Z9foo_largev
+// CHECK: call void @llvm.lifetime.end
+// CHECK: call void @llvm.lifetime.start
+// CHECK: call void @_Z9foo_largev
+// CHECK: call void @llvm.lifetime.end
+
+  {
+    S_large s = foo_large();
+  }
+  {
+    S_large s = foo_large();
+  }
+}
+
+void small_auto_object() {
+// CHECK-LABEL: define void @small_auto_object
+// CHECK: call void @llvm.lifetime.start
+// CHECK: call void @_Z9bar_smallP7S_small
+// CHECK: call void @llvm.lifetime.end
+// CHECK: call void @llvm.lifetime.start
+// CHECK: call void @_Z9bar_smallP7S_small
+// CHECK: call void @llvm.lifetime.end
+
+  {
+    S_small s;
+    bar_small(&s);
+  }
+  {
+    S_small s;
+    bar_small(&s);
+  }
+}
+
+void large_auto_object() {
+// CHECK-LABEL: define void @large_auto_object
+// CHECK: call void @llvm.lifetime.start
+// CHECK: call void @_Z9bar_largeP7S_large
+// CHECK: call void @llvm.lifetime.end
+// CHECK: call void @llvm.lifetime.start
+// CHECK: call void @_Z9bar_largeP7S_large
+// CHECK: call void @llvm.lifetime.end
+
+  {
+    S_large s;
+    bar_large(&s);
+  }
+  {
+    S_large s;
+    bar_large(&s);
+  }
+}
+
+int large_combiner_test(S_large s) {
+// CHECK-LABEL: define i32 @large_combiner_test
+// CHECK: %1 = alloca %struct.Combiner
+// CHECK: %2 = alloca %struct.Combiner
+// CHECK: %3 = call %struct.Combiner* @_ZN8CombinerC1E7S_large(%struct.Combiner* %1, [9 x i32] %s.coerce)
+// CHECK: call void @_ZN8Combiner1fEv(%struct.Combiner* sret %2, %struct.Combiner* %1)
+// CHECK: %4 = getelementptr inbounds %struct.Combiner, %struct.Combiner* %2, i32 0, i32 0, i32 0, i32 0
+// CHECK: %5 = load i32, i32* %4
+// CHECK: ret i32 %5
+
+  return Combiner(s).f().a.a[0];
+}
+
+}