clang/test/CodeGenCXX/virtual-function-elimination.cpp

   1 // RUN: %clang_cc1 -triple x86_64-unknown-linux -flto -flto-unit -fvirtual-function-elimination -fwhole-program-vtables -emit-llvm -o - %s | FileCheck %s
   2 // RUN: %clang -target x86_64-unknown-linux -flto -fvirtual-function-elimination -fno-virtual-function-elimination -fwhole-program-vtables -S -emit-llvm -o - %s | FileCheck %s -check-prefix=NOVFE
   3
   4 struct __attribute__((visibility("default"))) A {
   5   virtual void foo();
   6 };
   7
   8 void test_1(A *p) {
   9   // A has default visibility, so no need for type.checked.load.
  10 // CHECK-LABEL: define{{.*}} void @_Z6test_1P1A
  11 // NOVFE-LABEL: define dso_local void @_Z6test_1P1A
  12 // CHECK: [[FN_PTR_ADDR:%.+]] = getelementptr inbounds ptr, ptr {{%.+}}, i64 0
  13 // NOVFE: [[FN_PTR_ADDR:%.+]] = getelementptr inbounds ptr, ptr {{%.+}}, i64 0
  14 // CHECK: [[FN_PTR:%.+]] = load ptr, ptr [[FN_PTR_ADDR]]
  15 // NOVFE: [[FN_PTR:%.+]] = load ptr, ptr [[FN_PTR_ADDR]]
  16 // CHECK: call void [[FN_PTR]](
  17 // NOVFE: call void [[FN_PTR]](
  18   p->foo();
  19 }
  20
  21
  22 struct __attribute__((visibility("hidden"))) [[clang::lto_visibility_public]] B {
  23   virtual void foo();
  24 };
  25
  26 void test_2(B *p) {
  27   // B has public LTO visibility, so no need for type.checked.load.
  28 // CHECK-LABEL: define{{.*}} void @_Z6test_2P1B
  29 // NOVFE-LABEL: define dso_local void @_Z6test_2P1B
  30 // CHECK: [[FN_PTR_ADDR:%.+]] = getelementptr inbounds ptr, ptr {{%.+}}, i64 0
  31 // NOVFE: [[FN_PTR_ADDR:%.+]] = getelementptr inbounds ptr, ptr {{%.+}}, i64 0
  32 // CHECK: [[FN_PTR:%.+]] = load ptr, ptr [[FN_PTR_ADDR]]
  33 // NOVFE: [[FN_PTR:%.+]] = load ptr, ptr [[FN_PTR_ADDR]]
  34 // CHECK: call void [[FN_PTR]](
  35 // NOVFE: call void [[FN_PTR]](
  36   p->foo();
  37 }
  38
  39
  40 struct __attribute__((visibility("hidden"))) C {
  41   virtual void foo();
  42   virtual void bar();
  43 };
  44
  45 void test_3(C *p) {
  46   // C has hidden visibility, so we generate type.checked.load to allow VFE.
  47 // CHECK-LABEL: define{{.*}} void @_Z6test_3P1C
  48 // NOVFE-LABEL: define dso_local void @_Z6test_3P1C
  49 // CHECK: [[LOAD:%.+]] = call { ptr, i1 } @llvm.type.checked.load(ptr {{%.+}}, i32 0, metadata !"_ZTS1C")
  50 // NOVFE: call i1 @llvm.type.test(ptr {{%.+}}, metadata !"_ZTS1C")
  51 // CHECK: [[FN_PTR:%.+]] = extractvalue { ptr, i1 } [[LOAD]], 0
  52 // NOVFE: [[FN_PTR:%.+]] = load ptr, ptr {{%.+}}, align 8
  53 // CHECK: call void [[FN_PTR]](
  54 // NOVFE: call void [[FN_PTR]](
  55   p->foo();
  56 }
  57
  58 void test_4(C *p) {
  59   // When using type.checked.load, we pass the vtable offset to the intrinsic,
  60   // rather than adding it to the pointer with a GEP.
  61 // CHECK-LABEL: define{{.*}} void @_Z6test_4P1C
  62 // NOVFE-LABEL: define dso_local void @_Z6test_4P1C
  63 // CHECK: [[LOAD:%.+]] = call { ptr, i1 } @llvm.type.checked.load(ptr {{%.+}}, i32 8, metadata !"_ZTS1C")
  64 // NOVFE: call i1 @llvm.type.test(ptr {{%.+}}, metadata !"_ZTS1C")
  65 // CHECK: [[FN_PTR:%.+]] = extractvalue { ptr, i1 } [[LOAD]], 0
  66 // NOVFE: [[FN_PTR:%.+]] = load ptr, ptr {{%.+}}, align 8
  67 // CHECK: call void [[FN_PTR]](
  68 // NOVFE: call void [[FN_PTR]](
  69   p->bar();
  70 }
  71
  72 void test_5(C *p, void (C::*q)(void)) {
  73   // We also use type.checked.load for the virtual side of member function
  74   // pointer calls. We use a GEP to calculate the address to load from and pass
  75   // 0 as the offset to the intrinsic, because we know that the load must be
  76   // from exactly the point marked by one of the function-type metadatas (in
  77   // this case "_ZTSM1CFvvE.virtual"). If we passed the offset from the member
  78   // function pointer to the intrinsic, this information would be lost. No
  79   // codegen changes on the non-virtual side.
  80 // CHECK-LABEL: define{{.*}} void @_Z6test_5P1CMS_FvvE(
  81 // NOVFE-LABEL: define dso_local void @_Z6test_5P1CMS_FvvE(
  82 // CHECK: [[FN_PTR_ADDR:%.+]] = getelementptr i8, ptr %vtable, i64 {{%.+}}
  83 // CHECK: [[LOAD:%.+]] = call { ptr, i1 } @llvm.type.checked.load(ptr [[FN_PTR_ADDR]], i32 0, metadata !"_ZTSM1CFvvE.virtual")
  84 // NOVFE-NOT: call { ptr, i1 } @llvm.type.checked.load(ptr {{%.+}}, i32 0, metadata !"_ZTSM1CFvvE.virtual")
  85 // NOVFE: call i1 @llvm.type.test(ptr {{%.+}}, metadata !"_ZTSM1CFvvE.virtual")
  86 // CHECK: [[FN_PTR:%.+]] = extractvalue { ptr, i1 } [[LOAD]], 0
  87 // NOVFE: [[FN_PTR:%.+]] = load ptr, ptr {{%.+}}, align 8
  88
  89 // CHECK: [[PHI:%.+]] = phi ptr [ [[FN_PTR]], {{.*}} ]
  90 // NOVFE: [[PHI:%.+]] = phi ptr [ [[FN_PTR]], {{.*}} ]
  91 // CHECK: call void [[PHI]](
  92 // NOVFE: call void [[PHI]](
  93   (p->*q)();
  94 }