llvm-project/clang/test/CodeGenCXX/internal-linkage.cpp

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// RUN: %clang_cc1 -emit-llvm -triple %itanium_abi_triple -o - %s | FileCheck %s
When a function or variable somehow depends on a type or declaration that is in an anonymous namespace, give that function or variable internal linkage. This change models an oddity of the C++ standard, where names declared in an anonymous namespace have external linkage but, because anonymous namespace are really "uniquely-named" namespaces, the names cannot be referenced from other translation units. That means that they have external linkage for semantic analysis, but the only sensible implementation for code generation is to give them internal linkage. We now model this notion via the UniqueExternalLinkage linkage type. There are several changes here: - Extended NamedDecl::getLinkage() to produce UniqueExternalLinkage when the declaration is in an anonymous namespace. - Added Type::getLinkage() to determine the linkage of a type, which is defined as the minimum linkage of the types (when we're dealing with a compound type that is not a struct/class/union). - Extended NamedDecl::getLinkage() to consider the linkage of the template arguments and template parameters of function template specializations and class template specializations. - Taught code generation to rely on NamedDecl::getLinkage() when determining the linkage of variables and functions, also considering the linkage of the types of those variables and functions (C++ only). Map UniqueExternalLinkage to internal linkage, taking out the explicit checks for isInAnonymousNamespace(). This fixes much of PR5792, which, as discovered by Anders Carlsson, is actually the reason behind the pass-manager assertion that causes the majority of clang-on-clang regression test failures. With this fix, Clang-built-Clang+LLVM passes 88% of its regression tests (up from 67%). The specific numbers are: LLVM: Expected Passes : 4006 Expected Failures : 32 Unsupported Tests : 40 Unexpected Failures: 736 Clang: Expected Passes : 1903 Expected Failures : 14 Unexpected Failures: 75 Overall: Expected Passes : 5909 Expected Failures : 46 Unsupported Tests : 40 Unexpected Failures: 811 Still to do: - Improve testing - Check whether we should allow the presence of types with InternalLinkage (in addition to UniqueExternalLinkage) given variables/functions internal linkage in C++, as mentioned in PR5792. - Determine how expensive the getLinkage() calls are in practice; consider caching the result in NamedDecl. - Assess the feasibility of Chris's idea in comment #1 of PR5792. llvm-svn: 95216
2010-02-03 17:33:45 +08:00
struct Global { Global(); };
template<typename T> struct X { X() {} };
When a function or variable somehow depends on a type or declaration that is in an anonymous namespace, give that function or variable internal linkage. This change models an oddity of the C++ standard, where names declared in an anonymous namespace have external linkage but, because anonymous namespace are really "uniquely-named" namespaces, the names cannot be referenced from other translation units. That means that they have external linkage for semantic analysis, but the only sensible implementation for code generation is to give them internal linkage. We now model this notion via the UniqueExternalLinkage linkage type. There are several changes here: - Extended NamedDecl::getLinkage() to produce UniqueExternalLinkage when the declaration is in an anonymous namespace. - Added Type::getLinkage() to determine the linkage of a type, which is defined as the minimum linkage of the types (when we're dealing with a compound type that is not a struct/class/union). - Extended NamedDecl::getLinkage() to consider the linkage of the template arguments and template parameters of function template specializations and class template specializations. - Taught code generation to rely on NamedDecl::getLinkage() when determining the linkage of variables and functions, also considering the linkage of the types of those variables and functions (C++ only). Map UniqueExternalLinkage to internal linkage, taking out the explicit checks for isInAnonymousNamespace(). This fixes much of PR5792, which, as discovered by Anders Carlsson, is actually the reason behind the pass-manager assertion that causes the majority of clang-on-clang regression test failures. With this fix, Clang-built-Clang+LLVM passes 88% of its regression tests (up from 67%). The specific numbers are: LLVM: Expected Passes : 4006 Expected Failures : 32 Unsupported Tests : 40 Unexpected Failures: 736 Clang: Expected Passes : 1903 Expected Failures : 14 Unexpected Failures: 75 Overall: Expected Passes : 5909 Expected Failures : 46 Unsupported Tests : 40 Unexpected Failures: 811 Still to do: - Improve testing - Check whether we should allow the presence of types with InternalLinkage (in addition to UniqueExternalLinkage) given variables/functions internal linkage in C++, as mentioned in PR5792. - Determine how expensive the getLinkage() calls are in practice; consider caching the result in NamedDecl. - Assess the feasibility of Chris's idea in comment #1 of PR5792. llvm-svn: 95216
2010-02-03 17:33:45 +08:00
namespace {
struct Anon { Anon() {} };
When a function or variable somehow depends on a type or declaration that is in an anonymous namespace, give that function or variable internal linkage. This change models an oddity of the C++ standard, where names declared in an anonymous namespace have external linkage but, because anonymous namespace are really "uniquely-named" namespaces, the names cannot be referenced from other translation units. That means that they have external linkage for semantic analysis, but the only sensible implementation for code generation is to give them internal linkage. We now model this notion via the UniqueExternalLinkage linkage type. There are several changes here: - Extended NamedDecl::getLinkage() to produce UniqueExternalLinkage when the declaration is in an anonymous namespace. - Added Type::getLinkage() to determine the linkage of a type, which is defined as the minimum linkage of the types (when we're dealing with a compound type that is not a struct/class/union). - Extended NamedDecl::getLinkage() to consider the linkage of the template arguments and template parameters of function template specializations and class template specializations. - Taught code generation to rely on NamedDecl::getLinkage() when determining the linkage of variables and functions, also considering the linkage of the types of those variables and functions (C++ only). Map UniqueExternalLinkage to internal linkage, taking out the explicit checks for isInAnonymousNamespace(). This fixes much of PR5792, which, as discovered by Anders Carlsson, is actually the reason behind the pass-manager assertion that causes the majority of clang-on-clang regression test failures. With this fix, Clang-built-Clang+LLVM passes 88% of its regression tests (up from 67%). The specific numbers are: LLVM: Expected Passes : 4006 Expected Failures : 32 Unsupported Tests : 40 Unexpected Failures: 736 Clang: Expected Passes : 1903 Expected Failures : 14 Unexpected Failures: 75 Overall: Expected Passes : 5909 Expected Failures : 46 Unsupported Tests : 40 Unexpected Failures: 811 Still to do: - Improve testing - Check whether we should allow the presence of types with InternalLinkage (in addition to UniqueExternalLinkage) given variables/functions internal linkage in C++, as mentioned in PR5792. - Determine how expensive the getLinkage() calls are in practice; consider caching the result in NamedDecl. - Assess the feasibility of Chris's idea in comment #1 of PR5792. llvm-svn: 95216
2010-02-03 17:33:45 +08:00
// CHECK: @_ZN12_GLOBAL__N_15anon0E = internal global
Global anon0;
}
// CHECK: @anon1 = internal global
Anon anon1;
// CHECK: @anon2 = internal global
X<Anon> anon2;
// rdar: // 8071804
char const * const xyzzy = "Hello, world!";
extern char const * const xyzzy;
char const * const *test1()
{
// CHECK: @_ZL5xyzzy = internal constant
return &xyzzy;
}
static char const * const static_xyzzy = "Hello, world!";
extern char const * const static_xyzzy;
char const * const *test2()
{
// CHECK: @_ZL12static_xyzzy = internal constant
return &static_xyzzy;
}
static char const * static_nonconst_xyzzy = "Hello, world!";
extern char const * static_nonconst_xyzzy;
char const * *test3()
{
// CHECK: @_ZL21static_nonconst_xyzzy = internal global
return &static_nonconst_xyzzy;
}
char const * extern_nonconst_xyzzy = "Hello, world!";
extern char const * extern_nonconst_xyzzy;
char const * *test4()
{
// CHECK: @extern_nonconst_xyzzy = global
return &extern_nonconst_xyzzy;
}
// PR10120
template <typename T> class klass {
virtual void f();
};
namespace { struct S; }
void foo () { klass<S> x; }
// CHECK: @_ZTV5klassIN12_GLOBAL__N_11SEE = internal unnamed_addr constant