llvm-project/clang/test/CodeGenCXX/explicit-instantiation.cpp

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// RUN: %clang_cc1 -emit-llvm -triple i686-pc-linux-gnu -std=c++1y -o - %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-NO-OPT
// RUN: %clang_cc1 -emit-llvm -triple i686-pc-linux-gnu -std=c++1y -O3 -disable-llvm-passes -o - %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-OPT
// RUN: %clang_cc1 -emit-llvm -triple i686-pc-win32 -std=c++1y -o - %s | FileCheck %s --check-prefix=CHECK-MS
// This check logically is attached to 'template int S<int>::i;' below.
// CHECK: @_ZN1SIiE1iE = weak_odr global i32
// This check is logically attached to 'template int ExportedStaticLocal::f<int>()' below.
// CHECK-OPT: @_ZZN19ExportedStaticLocal1fIiEEvvE1i = linkonce_odr global
template<typename T, typename U, typename Result>
struct plus {
Result operator()(const T& t, const U& u) const;
};
template<typename T, typename U, typename Result>
Result plus<T, U, Result>::operator()(const T& t, const U& u) const {
return t + u;
}
// CHECK-LABEL: define weak_odr i32 @_ZNK4plusIillEclERKiRKl
template struct plus<int, long, long>;
namespace EarlyInstantiation {
// Check that we emit definitions if we instantiate a function definition before
// it gets explicitly instantiatied.
template<typename T> struct S {
constexpr int constexpr_function() { return 0; }
auto deduced_return_type() { return 0; }
};
// From an implicit instantiation.
constexpr int a = S<char>().constexpr_function();
int b = S<char>().deduced_return_type();
// From an explicit instantiation declaration.
extern template struct S<int>;
constexpr int c = S<int>().constexpr_function();
int d = S<int>().deduced_return_type();
// CHECK: define weak_odr i32 @_ZN18EarlyInstantiation1SIcE18constexpr_functionEv(
// CHECK: define weak_odr i32 @_ZN18EarlyInstantiation1SIcE19deduced_return_typeEv(
// CHECK: define weak_odr i32 @_ZN18EarlyInstantiation1SIiE18constexpr_functionEv(
// CHECK: define weak_odr i32 @_ZN18EarlyInstantiation1SIiE19deduced_return_typeEv(
template struct S<char>;
template struct S<int>;
template<typename T> constexpr int constexpr_function() { return 0; }
template<typename T> auto deduced_return_type() { return 0; }
// From an implicit instantiation.
constexpr int e = constexpr_function<char>();
int f = deduced_return_type<char>();
// From an explicit instantiation declaration.
extern template int constexpr_function<int>();
extern template auto deduced_return_type<int>();
constexpr int g = constexpr_function<int>();
int h = deduced_return_type<int>();
// The FIXMEs below are for PR19551.
// CHECK: define weak_odr i32 @_ZN18EarlyInstantiation18constexpr_functionIcEEiv(
// FIXME: define weak_odr i32 @_ZN18EarlyInstantiation19deduced_return_typeIcEEiv(
// CHECK: define weak_odr i32 @_ZN18EarlyInstantiation18constexpr_functionIiEEiv(
// FIXME: define weak_odr i32 @_ZN18EarlyInstantiation19deduced_return_typeIiEEiv(
template int constexpr_function<char>();
// FIXME template auto deduced_return_type<char>();
template int constexpr_function<int>();
// FIXME template auto deduced_return_type<int>();
}
namespace LateInstantiation {
// Check that we downgrade the linkage to available_externally if we see an
// explicit instantiation declaration after the function template is
// instantiated.
template<typename T> struct S { constexpr int f() { return 0; } };
template<typename T> constexpr int f() { return 0; }
// Trigger eager instantiation of the function definitions.
int a, b = S<char>().f() + f<char>() + a;
int c, d = S<int>().f() + f<int>() + a;
// Don't allow some of those definitions to be emitted.
extern template struct S<int>;
extern template int f<int>();
// Check that we declare, define, or provide an available-externally
// definition as appropriate.
// CHECK: define linkonce_odr i32 @_ZN17LateInstantiation1SIcE1fEv(
// CHECK: define linkonce_odr i32 @_ZN17LateInstantiation1fIcEEiv(
// CHECK-NO-OPT: declare i32 @_ZN17LateInstantiation1SIiE1fEv(
// CHECK-NO-OPT: declare i32 @_ZN17LateInstantiation1fIiEEiv(
// CHECK-OPT: define available_externally i32 @_ZN17LateInstantiation1SIiE1fEv(
// CHECK-OPT: define available_externally i32 @_ZN17LateInstantiation1fIiEEiv(
}
namespace PR21718 {
// The linkage of a used constexpr member function can change from linkonce_odr
// to weak_odr after explicit instantiation without errors about defining the
// same function twice.
template <typename T>
struct S {
// CHECK-LABEL: define weak_odr i32 @_ZN7PR217181SIiE1fEv
__attribute__((used)) constexpr int f() { return 0; }
};
int g() { return S<int>().f(); }
template struct S<int>;
}
namespace NestedClasses {
// Check how explicit instantiation of an outer class affects the inner class.
template <typename T> struct Outer {
struct Inner {
void f() {}
};
};
// Explicit instantiation definition of Outer causes explicit instantiation
// definition of Inner.
template struct Outer<int>;
// CHECK: define weak_odr void @_ZN13NestedClasses5OuterIiE5Inner1fEv
// CHECK-MS: define weak_odr dso_local x86_thiscallcc void @"?f@Inner@?$Outer@H@NestedClasses@@QAEXXZ"
// Explicit instantiation declaration of Outer causes explicit instantiation
// declaration of Inner, but not in MSVC mode.
extern template struct Outer<char>;
auto use = &Outer<char>::Inner::f;
// CHECK: {{declare|define available_externally}} void @_ZN13NestedClasses5OuterIcE5Inner1fEv
// CHECK-MS: define linkonce_odr dso_local x86_thiscallcc void @"?f@Inner@?$Outer@D@NestedClasses@@QAEXXZ"
}
// Check that we emit definitions from explicit instantiations even when they
// occur prior to the definition itself.
template <typename T> struct S {
void f();
static void g();
static int i;
struct S2 {
void h();
};
};
// CHECK-LABEL: define weak_odr void @_ZN1SIiE1fEv
template void S<int>::f();
// CHECK-LABEL: define weak_odr void @_ZN1SIiE1gEv
template void S<int>::g();
// See the check line at the top of the file.
template int S<int>::i;
// CHECK-LABEL: define weak_odr void @_ZN1SIiE2S21hEv
template void S<int>::S2::h();
template <typename T> void S<T>::f() {}
template <typename T> void S<T>::g() {}
template <typename T> int S<T>::i;
template <typename T> void S<T>::S2::h() {}
namespace ExportedStaticLocal {
void sink(int&);
template <typename T>
inline void f() {
static int i;
sink(i);
}
// See the check line at the top of the file.
extern template void f<int>();
void use() {
f<int>();
}
}
namespace DefaultedMembers {
struct B { B(); B(const B&); ~B(); };
template<typename T> struct A : B {
A() = default;
~A() = default;
};
extern template struct A<int>;
// CHECK-LABEL: define {{.*}} @_ZN16DefaultedMembers1AIiEC2Ev
// CHECK-LABEL: define {{.*}} @_ZN16DefaultedMembers1AIiED2Ev
A<int> ai;
// CHECK-LABEL: define {{.*}} @_ZN16DefaultedMembers1AIiEC2ERKS1_
A<int> ai2(ai);
// CHECK-NOT: @_ZN16DefaultedMembers1AIcE
template struct A<char>;
}