clang/test/CodeGenCXX/RelativeVTablesABI/dynamic-cast.cpp

   1 // dynamic_cast
   2 // Ensure that dynamic casting works normally
   3
   4 // RUN: %clang_cc1 %s -triple=aarch64-unknown-fuchsia -O3 -S -o - -emit-llvm | FileCheck %s
   5
   6 // CHECK:      define{{.*}} ptr @_Z6upcastP1B(ptr noundef readnone returned %b) local_unnamed_addr
   7 // CHECK-NEXT: entry:
   8 // CHECK-NEXT:   ret ptr %b
   9 // CHECK-NEXT: }
  10
  11 // CHECK:      define{{.*}} ptr @_Z8downcastP1A(ptr noundef readonly %a) local_unnamed_addr
  12 // CHECK-NEXT: entry:
  13 // CHECK-NEXT:   [[isnull:%[0-9]+]] = icmp eq ptr %a, null
  14 // CHECK-NEXT:   br i1 [[isnull]], label %[[dynamic_cast_end:[a-z0-9._]+]], label %[[dynamic_cast_notnull:[a-z0-9._]+]]
  15 // CHECK:      [[dynamic_cast_notnull]]:
  16 // CHECK-NEXT:   [[as_b:%[0-9]+]] = tail call ptr @__dynamic_cast(ptr nonnull %a, ptr nonnull @_ZTI1A, ptr nonnull @_ZTI1B, i64 0)
  17 // CHECK-NEXT:   br label %[[dynamic_cast_end]]
  18 // CHECK:      [[dynamic_cast_end]]:
  19 // CHECK-NEXT:   [[res:%[0-9]+]] = phi ptr [ [[as_b]], %[[dynamic_cast_notnull]] ], [ null, %entry ]
  20 // CHECK-NEXT:   ret ptr [[res]]
  21 // CHECK-NEXT: }
  22
  23 // CHECK: declare ptr @__dynamic_cast(ptr, ptr, ptr, i64) local_unnamed_addr
  24
  25 // CHECK:      define{{.*}} ptr @_Z8selfcastP1B(ptr noundef readnone returned %b) local_unnamed_addr
  26 // CHECK-NEXT: entry
  27 // CHECK-NEXT:   ret ptr %b
  28 // CHECK-NEXT: }
  29
  30 // CHECK: define{{.*}} ptr @_Z9void_castP1B(ptr noundef readonly %b) local_unnamed_addr
  31 // CHECK-NEXT: entry:
  32 // CHECK-NEXT:   [[isnull:%[0-9]+]] = icmp eq ptr %b, null
  33 // CHECK-NEXT:   br i1 [[isnull]], label %[[dynamic_cast_end:[a-z0-9._]+]], label %[[dynamic_cast_notnull:[a-z0-9._]+]]
  34 // CHECK:      [[dynamic_cast_notnull]]:
  35 // CHECK-DAG:    [[vtable:%[a-z0-9]+]] = load ptr, ptr %b, align 8
  36 // CHECK-DAG:    [[offset_ptr:%.+]] = getelementptr inbounds i32, ptr [[vtable]], i64 -2
  37 // CHECK-DAG:    [[offset_to_top:%.+]] = load i32, ptr [[offset_ptr]], align 4
  38 // CHECK-DAG:    [[offset_to_top2:%.+]] = sext i32 [[offset_to_top]] to i64
  39 // CHECK-DAG:    [[casted:%.+]] = getelementptr inbounds i8, ptr %b, i64 [[offset_to_top2]]
  40 // CHECK-NEXT:   br label %[[dynamic_cast_end]]
  41 // CHECK:      [[dynamic_cast_end]]:
  42 // CHECK-NEXT:   [[res:%[0-9]+]] = phi ptr [ [[casted]], %[[dynamic_cast_notnull]] ], [ null, %entry ]
  43 // CHECK-NEXT:   ret ptr [[res]]
  44 // CHECK-NEXT: }
  45
  46 class A {
  47 public:
  48   virtual void foo();
  49 };
  50
  51 class B : public A {
  52 public:
  53   void foo() override;
  54 };
  55
  56 void A::foo() {}
  57 void B::foo() {}
  58
  59 A *upcast(B *b) {
  60   return dynamic_cast<A *>(b);
  61 }
  62
  63 B *downcast(A *a) {
  64   return dynamic_cast<B *>(a);
  65 }
  66
  67 B *selfcast(B *b) {
  68   return dynamic_cast<B *>(b);
  69 }
  70
  71 void *void_cast(B *b) {
  72   return dynamic_cast<void *>(b);
  73 }