xref: /llvm-project/clang/test/CodeGenCXX/tail-padding.cpp (revision 3512721d52b3380ea4d3f5b2419d0b7b072e7797)
1 // RUN: %clang_cc1 -triple %itanium_abi_triple -emit-llvm -o - %s | FileCheck %s
2 
3 // PR36992
4 namespace Implicit {
5   struct A { char c; A(const A&); };
6   struct B { int n; char c[3]; ~B(); };
7   struct C : B, virtual A {};
8   static_assert(sizeof(C) == sizeof(void*) + 8);
f(C c)9   C f(C c) { return c; }
10 
11   // CHECK: define {{.*}} @_ZN8Implicit1CC1EOS0_
12   // CHECK: call {{.*}} @_ZN8Implicit1AC2ERKS0_(
13   // Note: this must memcpy 7 bytes, not 8, to avoid trampling over the virtual base class.
14   // CHECK: call void @llvm.memcpy.p0.p0.i{{32|64}}(ptr {{.*}}, ptr {{.*}}, i{{32|64}} 7, i1 false)
15   // CHECK: store ptr {{.*}} @_ZTVN8Implicit1CE
16 }
17 
18 namespace InitWithinNVSize {
19   // This is the same as the previous test, except that the A base lies
20   // entirely within the nvsize of C. This makes it valid to copy at the
21   // full width.
22   struct A { char c; A(const A&); };
23   struct B { int n; char c[3]; ~B(); };
24   struct C : B, virtual A { char x; };
25   static_assert(sizeof(C) > sizeof(void*) + 8);
f(C c)26   C f(C c) { return c; }
27 
28   // CHECK: define {{.*}} @_ZN16InitWithinNVSize1CC1EOS0_
29   // CHECK: call {{.*}} @_ZN16InitWithinNVSize1AC2ERKS0_(
30   // This copies over the 'C::x' member, but that's OK because we've not initialized it yet.
31   // CHECK: call void @llvm.memcpy.p0.p0.i{{32|64}}(ptr {{.*}}, ptr {{.*}}, i{{32|64}} 8, i1 false)
32   // CHECK: store ptr {{.*}} @_ZTVN16InitWithinNVSize1CE
33   // CHECK: store i8
34 }
35 
36 namespace NoUniqueAddr {
37   struct A { char c; A(const A&); };
38   struct B { int n; char c[3]; ~B(); };
39   struct C : virtual A { B b; };
40   struct D : virtual A { [[no_unique_address]] B b; };
41   struct E : virtual A { [[no_unique_address]] B b; char x; };
42   static_assert(sizeof(C) == sizeof(void*) + 8 + alignof(void*));
43   static_assert(sizeof(D) == sizeof(void*) + 8);
44   static_assert(sizeof(E) == sizeof(void*) + 8 + alignof(void*));
45 
46   // CHECK: define {{.*}} @_ZN12NoUniqueAddr1CC1EOS0_
47   // CHECK: call {{.*}} @_ZN12NoUniqueAddr1AC2ERKS0_(
48   // CHECK: store ptr {{.*}} @_ZTVN12NoUniqueAddr1CE
49   // Copy the full size of B.
50   // CHECK: call void @llvm.memcpy.p0.p0.i{{32|64}}(ptr {{.*}}, ptr {{.*}}, i{{32|64}} 8, i1 false)
f(C c)51   C f(C c) { return c; }
52 
53   // CHECK: define {{.*}} @_ZN12NoUniqueAddr1DC1EOS0_
54   // CHECK: call {{.*}} @_ZN12NoUniqueAddr1AC2ERKS0_(
55   // CHECK: store ptr {{.*}} @_ZTVN12NoUniqueAddr1DE
56   // Copy just the data size of B, to avoid overwriting the A base class.
57   // CHECK: call void @llvm.memcpy.p0.p0.i{{32|64}}(ptr {{.*}}, ptr {{.*}}, i{{32|64}} 7, i1 false)
f(D d)58   D f(D d) { return d; }
59 
60   // CHECK: define {{.*}} @_ZN12NoUniqueAddr1EC1EOS0_
61   // CHECK: call {{.*}} @_ZN12NoUniqueAddr1AC2ERKS0_(
62   // CHECK: store ptr {{.*}} @_ZTVN12NoUniqueAddr1EE
63   // We can copy the full size of B here. (As it happens, we fold the copy of 'x' into
64   // this memcpy, so we're copying 8 bytes either way.)
65   // CHECK: call void @llvm.memcpy.p0.p0.i{{32|64}}(ptr {{.*}}, ptr {{.*}}, i{{32|64}} 8, i1 false)
f(E e)66   E f(E e) { return e; }
67 
68   struct F : virtual A {
FNoUniqueAddr::F69     F(const F &o) : A(o), b(o.b) {}
70     [[no_unique_address]] B b;
71   };
72 
73   // CHECK: define {{.*}} @_ZN12NoUniqueAddr1FC1ERKS0_
74   // CHECK: call {{.*}} @_ZN12NoUniqueAddr1AC2ERKS0_(
75   // CHECK: store ptr {{.*}} @_ZTVN12NoUniqueAddr1FE
76   // CHECK: call void @llvm.memcpy.p0.p0.i{{32|64}}(ptr {{.*}}, ptr {{.*}}, i{{32|64}} 7, i1 false)
f(F x)77   F f(F x) { return x; }
78 }
79