clang/test/CodeGenCXX/RelativeVTablesABI/multiple-inheritance.cpp

   1 // Multiple inheritance.
   2
   3 // RUN: %clang_cc1 %s -triple=aarch64-unknown-fuchsia -O1 -S -o - -emit-llvm -fhalf-no-semantic-interposition | FileCheck %s
   4
   5 // VTable for C contains 2 sub-vtables (represented as 2 structs). The first contains the components for B and the second contains the components for C. The RTTI ptr in both arrays still point to the RTTI struct for C.
   6 // The component for bar() instead points to a thunk which redirects to C::bar() which overrides B::bar().
   7 // Now that we have a class with 2 parents, the offset to top in the second array is non-zero.
   8 // CHECK: @_ZTV1C.local = private unnamed_addr constant { [4 x i32], [3 x i32] } { [4 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr @_ZTI1C.rtti_proxy to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [4 x i32], [3 x i32] }, ptr @_ZTV1C.local, i32 0, i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @_ZN1C3fooEv to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [4 x i32], [3 x i32] }, ptr @_ZTV1C.local, i32 0, i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @_ZN1C3barEv to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [4 x i32], [3 x i32] }, ptr @_ZTV1C.local, i32 0, i32 0, i32 2) to i64)) to i32)], [3 x i32] [i32 -8, i32 trunc (i64 sub (i64 ptrtoint (ptr @_ZTI1C.rtti_proxy to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [4 x i32], [3 x i32] }, ptr @_ZTV1C.local, i32 0, i32 1, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @_ZThn8_N1C3barEv to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [4 x i32], [3 x i32] }, ptr @_ZTV1C.local, i32 0, i32 1, i32 2) to i64)) to i32)] }, align 4
   9
  10 // CHECK: @_ZTV1C ={{.*}} unnamed_addr alias { [4 x i32], [3 x i32] }, ptr @_ZTV1C.local
  11
  12 // CHECK:      define{{.*}} void @_Z8C_foobarP1C(ptr noundef %c) local_unnamed_addr
  13 // CHECK-NEXT: entry:
  14 // CHECK-NEXT:   [[vtable:%[a-z0-9]+]] = load ptr, ptr %c, align 8
  15
  16 // Offset 0 to get first method
  17 // CHECK-NEXT:   [[ptr1:%[0-9]+]] = tail call ptr @llvm.load.relative.i32(ptr [[vtable]], i32 0)
  18 // CHECK-NEXT:   call void [[ptr1]](ptr {{[^,]*}} %c)
  19 // CHECK-NEXT:   [[vtable:%[a-z0-9]+]] = load ptr, ptr %c, align 8
  20
  21 // Offset by 4 to get the next bar()
  22 // CHECK-NEXT:   [[ptr2:%[0-9]+]] = tail call ptr @llvm.load.relative.i32(ptr [[vtable]], i32 4)
  23 // CHECK-NEXT:   call void [[ptr2]](ptr {{[^,]*}} %c)
  24 // CHECK-NEXT:   ret void
  25 // CHECK-NEXT: }
  26
  27 class A {
  28 public:
  29   virtual void foo();
  30 };
  31
  32 class B {
  33   virtual void bar();
  34 };
  35
  36 class C : public A, public B {
  37 public:
  38   void foo() override;
  39   void bar() override;
  40 };
  41
  42 void C::foo() {}
  43 void C::bar() {}
  44
  45 void C_foobar(C *c) {
  46   c->foo();
  47   c->bar();
  48 }