1 files changed, 75 insertions, 0 deletions
diff --git a/clang/test/CodeGenCXX/virtual-function-elimination.cpp b/clang/test/CodeGenCXX/virtual-function-elimination.cpp
new file mode 100644
index 00000000000..a89e6ebceea
--- /dev/null
+++ b/clang/test/CodeGenCXX/virtual-function-elimination.cpp
@@ -0,0 +1,75 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -flto -flto-unit -fvirtual-function-elimination -fwhole-program-vtables -emit-llvm -o - %s | FileCheck %s
+
+
+struct __attribute__((visibility("default"))) A {
+  virtual void foo();
+};
+
+void test_1(A *p) {
+  // A has default visibility, so no need for type.checked.load.
+// CHECK-LABEL: define void @_Z6test_1P1A
+// CHECK: [[FN_PTR_ADDR:%.+]] = getelementptr inbounds void (%struct.A*)*, void (%struct.A*)** {{%.+}}, i64 0
+// CHECK: [[FN_PTR:%.+]] = load void (%struct.A*)*, void (%struct.A*)** [[FN_PTR_ADDR]]
+// CHECK: call void [[FN_PTR]](
+  p->foo();
+}
+
+
+struct __attribute__((visibility("hidden"))) [[clang::lto_visibility_public]] B {
+  virtual void foo();
+};
+
+void test_2(B *p) {
+  // B has public LTO visibility, so no need for type.checked.load.
+// CHECK-LABEL: define void @_Z6test_2P1B
+// CHECK: [[FN_PTR_ADDR:%.+]] = getelementptr inbounds void (%struct.B*)*, void (%struct.B*)** {{%.+}}, i64 0
+// CHECK: [[FN_PTR:%.+]] = load void (%struct.B*)*, void (%struct.B*)** [[FN_PTR_ADDR]]
+// CHECK: call void [[FN_PTR]](
+  p->foo();
+}
+
+
+struct __attribute__((visibility("hidden"))) C {
+  virtual void foo();
+  virtual void bar();
+};
+
+void test_3(C *p) {
+  // C has hidden visibility, so we generate type.checked.load to allow VFE.
+// CHECK-LABEL: define void @_Z6test_3P1C
+// CHECK: [[LOAD:%.+]] = call { i8*, i1 } @llvm.type.checked.load(i8* {{%.+}}, i32 0, metadata !"_ZTS1C")
+// CHECK: [[FN_PTR_I8:%.+]] = extractvalue { i8*, i1 } [[LOAD]], 0
+// CHECK: [[FN_PTR:%.+]] = bitcast i8* [[FN_PTR_I8]] to void (%struct.C*)*
+// CHECK: call void [[FN_PTR]](
+  p->foo();
+}
+
+void test_4(C *p) {
+  // When using type.checked.load, we pass the vtable offset to the intrinsic,
+  // rather than adding it to the pointer with a GEP.
+// CHECK-LABEL: define void @_Z6test_4P1C
+// CHECK: [[LOAD:%.+]] = call { i8*, i1 } @llvm.type.checked.load(i8* {{%.+}}, i32 8, metadata !"_ZTS1C")
+// CHECK: [[FN_PTR_I8:%.+]] = extractvalue { i8*, i1 } [[LOAD]], 0
+// CHECK: [[FN_PTR:%.+]] = bitcast i8* [[FN_PTR_I8]] to void (%struct.C*)*
+// CHECK: call void [[FN_PTR]](
+  p->bar();
+}
+
+void test_5(C *p, void (C::*q)(void)) {
+  // We also use type.checked.load for the virtual side of member function
+  // pointer calls. We use a GEP to calculate the address to load from and pass
+  // 0 as the offset to the intrinsic, because we know that the load must be
+  // from exactly the point marked by one of the function-type metadatas (in
+  // this case "_ZTSM1CFvvE.virtual"). If we passed the offset from the member
+  // function pointer to the intrinsic, this information would be lost. No
+  // codegen changes on the non-virtual side.
+// CHECK-LABEL: define void @_Z6test_5P1CMS_FvvE(
+// CHECK: [[FN_PTR_ADDR:%.+]] = getelementptr i8, i8* %vtable, i64 {{%.+}}
+// CHECK: [[LOAD:%.+]] = call { i8*, i1 } @llvm.type.checked.load(i8* [[FN_PTR_ADDR]], i32 0, metadata !"_ZTSM1CFvvE.virtual")
+// CHECK: [[FN_PTR_I8:%.+]] = extractvalue { i8*, i1 } [[LOAD]], 0
+// CHECK: [[FN_PTR:%.+]] = bitcast i8* [[FN_PTR_I8]] to void (%struct.C*)*
+
+// CHECK: [[PHI:%.+]] = phi void (%struct.C*)* {{.*}}[ [[FN_PTR]], {{.*}} ]
+// CHECK: call void [[PHI]](
+  (p->*q)();
+}