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[Clang] Add __builtin_launder 

Summary:
This patch adds `__builtin_launder`, which is required to implement `std::launder`. Additionally GCC provides `__builtin_launder`, so thing brings Clang in-line with GCC.

I'm not exactly sure what magic `__builtin_launder` requires, but  based on previous discussions this patch applies a `@llvm.invariant.group.barrier`. As noted in previous discussions, this may not be enough to correctly handle vtables.

Reviewers: rnk, majnemer, rsmith

Reviewed By: rsmith

Subscribers: kristina, Romain-Geissler-1A, erichkeane, amharc, jroelofs, cfe-commits, Prazek

Differential Revision: https://reviews.llvm.org/D40218

llvm-svn: 349195
This commit is contained in:
Eric Fiselier 2018-12-14 21:11:28 +00:00
parent 8f06d10291
commit 261875054e
10 changed files with 558 additions and 1 deletions
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1
clang/include/clang/Basic/Builtins.def
View File

@ -498,6 +498,7 @@ BUILTIN(__builtin_snprintf, "ic*zcC*.", "nFp:2:")
BUILTIN(__builtin_vsprintf, "ic*cC*a", "nFP:1:")
BUILTIN(__builtin_vsnprintf, "ic*zcC*a", "nFP:2:")
BUILTIN(__builtin_thread_pointer, "v*", "nc")
BUILTIN(__builtin_launder, "v*v*", "nt")
// GCC exception builtins
BUILTIN(__builtin_eh_return, "vzv*", "r") // FIXME: Takes intptr_t, not size_t!

4
clang/include/clang/Basic/DiagnosticSemaKinds.td
View File

@ -9475,4 +9475,8 @@ def warn_noderef_on_non_pointer_or_array : Warning<
def warn_noderef_to_dereferenceable_pointer : Warning<
"casting to dereferenceable pointer removes 'noderef' attribute">, InGroup<NoDeref>;
def err_builtin_launder_invalid_arg : Error<
"%select{non-pointer|function pointer|void pointer}0 argument to "
"'__builtin_launder' is not allowed">;
} // end of sema component.

3
clang/lib/AST/ExprConstant.cpp
View File

@ -6112,7 +6112,8 @@ bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
return true;
}
case Builtin::BI__builtin_launder:
return evaluatePointer(E->getArg(0), Result);
case Builtin::BIstrchr:
case Builtin::BIwcschr:
case Builtin::BImemchr:

46
clang/lib/CodeGen/CGBuiltin.cpp
View File

@ -25,6 +25,7 @@
#include "clang/Basic/TargetBuiltins.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/CodeGen/CGFunctionInfo.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/DataLayout.h"
@ -1409,6 +1410,42 @@ static llvm::Value *dumpRecord(CodeGenFunction &CGF, QualType RType,
return Res;
}
static bool
TypeRequiresBuiltinLaunderImp(const ASTContext &Ctx, QualType Ty,
llvm::SmallPtrSetImpl<const Decl *> &Seen) {
if (const auto *Arr = Ctx.getAsArrayType(Ty))
Ty = Ctx.getBaseElementType(Arr);
const auto *Record = Ty->getAsCXXRecordDecl();
if (!Record)
return false;
// We've already checked this type, or are in the process of checking it.
if (!Seen.insert(Record).second)
return false;
assert(Record->hasDefinition() &&
"Incomplete types should already be diagnosed");
if (Record->isDynamicClass())
return true;
for (FieldDecl *F : Record->fields()) {
if (TypeRequiresBuiltinLaunderImp(Ctx, F->getType(), Seen))
return true;
}
return false;
}
/// Determine if the specified type requires laundering by checking if it is a
/// dynamic class type or contains a subobject which is a dynamic class type.
static bool TypeRequiresBuiltinLaunder(CodeGenModule &CGM, QualType Ty) {
if (!CGM.getCodeGenOpts().StrictVTablePointers)
return false;
llvm::SmallPtrSet<const Decl *, 16> Seen;
return TypeRequiresBuiltinLaunderImp(CGM.getContext(), Ty, Seen);
}
RValue CodeGenFunction::emitRotate(const CallExpr *E, bool IsRotateRight) {
llvm::Value *Src = EmitScalarExpr(E->getArg(0));
llvm::Value *ShiftAmt = EmitScalarExpr(E->getArg(1));
@ -2474,6 +2511,15 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
return RValue::get(nullptr);
}
case Builtin::BI__builtin_launder: {
const Expr *Arg = E->getArg(0);
QualType ArgTy = Arg->getType()->getPointeeType();
Value *Ptr = EmitScalarExpr(Arg);
if (TypeRequiresBuiltinLaunder(CGM, ArgTy))
Ptr = Builder.CreateLaunderInvariantGroup(Ptr);
return RValue::get(Ptr);
}
case Builtin::BI__sync_fetch_and_add:
case Builtin::BI__sync_fetch_and_sub:
case Builtin::BI__sync_fetch_and_or:

62
clang/lib/Sema/SemaChecking.cpp
View File

@ -880,6 +880,66 @@ static bool SemaOpenCLBuiltinToAddr(Sema &S, unsigned BuiltinID,
return false;
}
static ExprResult SemaBuiltinLaunder(Sema &S, CallExpr *TheCall) {
if (checkArgCount(S, TheCall, 1))
return ExprError();
// Compute __builtin_launder's parameter type from the argument.
// The parameter type is:
// * The type of the argument if it's not an array or function type,
// Otherwise,
// * The decayed argument type.
QualType ParamTy = [&]() {
QualType ArgTy = TheCall->getArg(0)->getType();
if (const ArrayType *Ty = ArgTy->getAsArrayTypeUnsafe())
return S.Context.getPointerType(Ty->getElementType());
if (ArgTy->isFunctionType()) {
return S.Context.getPointerType(ArgTy);
}
return ArgTy;
}();
TheCall->setType(ParamTy);
auto DiagSelect = [&]() -> llvm::Optional<unsigned> {
if (!ParamTy->isPointerType())
return 0;
if (ParamTy->isFunctionPointerType())
return 1;
if (ParamTy->isVoidPointerType())
return 2;
return llvm::Optional<unsigned>{};
}();
if (DiagSelect.hasValue()) {
S.Diag(TheCall->getBeginLoc(), diag::err_builtin_launder_invalid_arg)
<< DiagSelect.getValue() << TheCall->getSourceRange();
return ExprError();
}
// We either have an incomplete class type, or we have a class template
// whose instantiation has not been forced. Example:
//
// template <class T> struct Foo { T value; };
// Foo<int> *p = nullptr;
// auto *d = __builtin_launder(p);
if (S.RequireCompleteType(TheCall->getBeginLoc(), ParamTy->getPointeeType(),
diag::err_incomplete_type))
return ExprError();
assert(ParamTy->getPointeeType()->isObjectType() &&
"Unhandled non-object pointer case");
InitializedEntity Entity =
InitializedEntity::InitializeParameter(S.Context, ParamTy, false);
ExprResult Arg =
S.PerformCopyInitialization(Entity, SourceLocation(), TheCall->getArg(0));
if (Arg.isInvalid())
return ExprError();
TheCall->setArg(0, Arg.get());
return TheCall;
}
// Emit an error and return true if the current architecture is not in the list
// of supported architectures.
static bool
@ -1042,6 +1102,8 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
if (checkArgCount(*this, TheCall, 1)) return true;
TheCall->setType(Context.IntTy);
break;
case Builtin::BI__builtin_launder:
return SemaBuiltinLaunder(*this, TheCall);
case Builtin::BI__sync_fetch_and_add:
case Builtin::BI__sync_fetch_and_add_1:
case Builtin::BI__sync_fetch_and_add_2:

11
clang/test/CodeGen/builtins.c
View File

@ -132,6 +132,8 @@ int main() {
R(extract_return_addr, (&N));
P(signbit, (1.0));
R(launder, (&N));
return 0;
}
@ -396,6 +398,15 @@ long long test_builtin_readcyclecounter() {
return __builtin_readcyclecounter();
}
/// __builtin_launder should be a NOP in C since there are no vtables.
// CHECK-LABEL: define void @test_builtin_launder
void test_builtin_launder(int *p) {
// CHECK: [[TMP:%.*]] = load i32*,
// CHECK-NOT: @llvm.launder
// CHECK: store i32* [[TMP]],
int *d = __builtin_launder(p);
}
// Behavior of __builtin_os_log differs between platforms, so only test on X86
#ifdef __x86_64__

321
clang/test/CodeGenCXX/builtin-launder.cpp Normal file
View File

@ -0,0 +1,321 @@
// RUN: %clang_cc1 -triple=x86_64-linux-gnu -emit-llvm -fstrict-vtable-pointers -o - %s \
// RUN: | FileCheck --check-prefixes=CHECK,CHECK-STRICT %s
// RUN: %clang_cc1 -triple=x86_64-linux-gnu -emit-llvm -o - %s \
// RUN: | FileCheck --check-prefixes=CHECK,CHECK-NONSTRICT %s
//===----------------------------------------------------------------------===//
// Positive Cases
//===----------------------------------------------------------------------===//
struct TestVirtualFn {
virtual void foo() {}
};
// CHECK-LABEL: define void @test_builtin_launder_virtual_fn
extern "C" void test_builtin_launder_virtual_fn(TestVirtualFn *p) {
// CHECK: store [[TYPE:%[^ ]+]] %p, [[TYPE]]* %p.addr
// CHECK-NEXT: [[TMP0:%.*]] = load [[TYPE]], [[TYPE]]* %p.addr
// CHECK-NONSTRICT-NEXT: store [[TYPE]] [[TMP0]], [[TYPE]]* %d
// CHECK-STRICT-NEXT: [[TMP1:%.*]] = bitcast [[TYPE]] [[TMP0]] to i8*
// CHECK-STRICT-NEXT: [[TMP2:%.*]] = call i8* @llvm.launder.invariant.group.p0i8(i8* [[TMP1]])
// CHECK-STRICT-NEXT: [[TMP3:%.*]] = bitcast i8* [[TMP2]] to [[TYPE]]
// CHECK-STRICT-NEXT: store [[TYPE]] [[TMP3]], [[TYPE]]* %d
// CHECK-NEXT: ret void
TestVirtualFn *d = __builtin_launder(p);
}
struct TestPolyBase : TestVirtualFn {
};
// CHECK-LABEL: define void @test_builtin_launder_poly_base
extern "C" void test_builtin_launder_poly_base(TestPolyBase *p) {
// CHECK-STRICT-NOT: ret void
// CHECK-STRICT: @llvm.launder.invariant.group
// CHECK-NONSTRICT-NOT: @llvm.launder.invariant.group
// CHECK: ret void
TestPolyBase *d = __builtin_launder(p);
}
struct TestBase {};
struct TestVirtualBase : virtual TestBase {};
// CHECK-LABEL: define void @test_builtin_launder_virtual_base
extern "C" void test_builtin_launder_virtual_base(TestVirtualBase *p) {
// CHECK-STRICT-NOT: ret void
// CHECK-STRICT: @llvm.launder.invariant.group
// CHECK-NONSTRICT-NOT: @llvm.launder.invariant.group
// CHECK: ret void
TestVirtualBase *d = __builtin_launder(p);
}
//===----------------------------------------------------------------------===//
// Negative Cases
//===----------------------------------------------------------------------===//
// CHECK-LABEL: define void @test_builtin_launder_ommitted_one
extern "C" void test_builtin_launder_ommitted_one(int *p) {
// CHECK: entry
// CHECK-NEXT: %p.addr = alloca i32*
// CHECK-NEXT: %d = alloca i32*
// CHECK-NEXT: store i32* %p, i32** %p.addr, align 8
// CHECK-NEXT: [[TMP:%.*]] = load i32*, i32** %p.addr
// CHECK-NEXT: store i32* [[TMP]], i32** %d
// CHECK-NEXT: ret void
int *d = __builtin_launder(p);
}
struct TestNoInvariant {
int x;
};
// CHECK-LABEL: define void @test_builtin_launder_ommitted_two
extern "C" void test_builtin_launder_ommitted_two(TestNoInvariant *p) {
// CHECK: entry
// CHECK-NOT: llvm.launder.invariant.group
// CHECK-NEXT: %p.addr = alloca [[TYPE:%.*]], align 8
// CHECK-NEXT: %d = alloca [[TYPE]]
// CHECK-NEXT: store [[TYPE]] %p, [[TYPE]]* %p.addr
// CHECK-NEXT: [[TMP:%.*]] = load [[TYPE]], [[TYPE]]* %p.addr
// CHECK-NEXT: store [[TYPE]] [[TMP]], [[TYPE]]* %d
// CHECK-NEXT: ret void
TestNoInvariant *d = __builtin_launder(p);
}
struct TestVirtualMember {
TestVirtualFn member;
};
// CHECK-LABEL: define void @test_builtin_launder_virtual_member
extern "C" void test_builtin_launder_virtual_member(TestVirtualMember *p) {
// CHECK: entry
// CHECK-NONSTRICT-NOT: @llvm.launder.invariant.group
// CHECK-STRICT: @llvm.launder.invariant.group
// CHECK: ret void
TestVirtualMember *d = __builtin_launder(p);
}
struct TestVirtualMemberDepth2 {
TestVirtualMember member;
};
// CHECK-LABEL: define void @test_builtin_launder_virtual_member_depth_2
extern "C" void test_builtin_launder_virtual_member_depth_2(TestVirtualMemberDepth2 *p) {
// CHECK: entry
// CHECK-NONSTRICT-NOT: @llvm.launder.invariant.group
// CHECK-STRICT: @llvm.launder.invariant.group
// CHECK: ret void
TestVirtualMemberDepth2 *d = __builtin_launder(p);
}
struct TestVirtualReferenceMember {
TestVirtualFn &member;
};
// CHECK-LABEL: define void @test_builtin_launder_virtual_reference_member
extern "C" void test_builtin_launder_virtual_reference_member(TestVirtualReferenceMember *p) {
// CHECK: entry
// CHECK-NOT: @llvm.launder.invariant.group
// CHECK: ret void
TestVirtualReferenceMember *d = __builtin_launder(p);
}
struct TestRecursiveMember {
TestRecursiveMember() : member(*this) {}
TestRecursiveMember &member;
};
// CHECK-LABEL: define void @test_builtin_launder_recursive_member
extern "C" void test_builtin_launder_recursive_member(TestRecursiveMember *p) {
// CHECK: entry
// CHECK-NOT: @llvm.launder.invariant.group
// CHECK: ret void
TestRecursiveMember *d = __builtin_launder(p);
}
struct TestVirtualRecursiveMember {
TestVirtualRecursiveMember() : member(*this) {}
TestVirtualRecursiveMember &member;
virtual void foo();
};
// CHECK-LABEL: define void @test_builtin_launder_virtual_recursive_member
extern "C" void test_builtin_launder_virtual_recursive_member(TestVirtualRecursiveMember *p) {
// CHECK: entry
// CHECK-NONSTRICT-NOT: @llvm.launder.invariant.group
// CHECK-STRICT: @llvm.launder.invariant.group
// CHECK: ret void
TestVirtualRecursiveMember *d = __builtin_launder(p);
}
// CHECK-LABEL: define void @test_builtin_launder_array(
extern "C" void test_builtin_launder_array(TestVirtualFn (&Arr)[5]) {
// CHECK: entry
// CHECK-NONSTRICT-NOT: @llvm.launder.invariant.group
// CHECK-STRICT: @llvm.launder.invariant.group
// CHECK: ret void
TestVirtualFn *d = __builtin_launder(Arr);
}
// CHECK-LABEL: define void @test_builtin_launder_array_nested(
extern "C" void test_builtin_launder_array_nested(TestVirtualFn (&Arr)[5][2]) {
// CHECK: entry
// CHECK-NONSTRICT-NOT: @llvm.launder.invariant.group
// CHECK-STRICT: @llvm.launder.invariant.group
// CHECK: ret void
using RetTy = TestVirtualFn(*)[2];
RetTy d = __builtin_launder(Arr);
}
// CHECK-LABEL: define void @test_builtin_launder_array_no_invariant(
extern "C" void test_builtin_launder_array_no_invariant(TestNoInvariant (&Arr)[5]) {
// CHECK: entry
// CHECK-NOT: @llvm.launder.invariant.group
// CHECK: ret void
TestNoInvariant *d = __builtin_launder(Arr);
}
// CHECK-LABEL: define void @test_builtin_launder_array_nested_no_invariant(
extern "C" void test_builtin_launder_array_nested_no_invariant(TestNoInvariant (&Arr)[5][2]) {
// CHECK: entry
// CHECK-NOT: @llvm.launder.invariant.group
// CHECK: ret void
using RetTy = TestNoInvariant(*)[2];
RetTy d = __builtin_launder(Arr);
}
template <class Member>
struct WithMember {
Member mem;
};
template struct WithMember<TestVirtualFn[5]>;
// CHECK-LABEL: define void @test_builtin_launder_member_array(
extern "C" void test_builtin_launder_member_array(WithMember<TestVirtualFn[5]> *p) {
// CHECK: entry
// CHECK-NONSTRICT-NOT: @llvm.launder.invariant.group
// CHECK-STRICT: @llvm.launder.invariant.group
// CHECK: ret void
auto *d = __builtin_launder(p);
}
template struct WithMember<TestVirtualFn[5][2]>;
// CHECK-LABEL: define void @test_builtin_launder_member_array_nested(
extern "C" void test_builtin_launder_member_array_nested(WithMember<TestVirtualFn[5][2]> *p) {
// CHECK: entry
// CHECK-NONSTRICT-NOT: @llvm.launder.invariant.group
// CHECK-STRICT: @llvm.launder.invariant.group
// CHECK: ret void
auto *d = __builtin_launder(p);
}
template struct WithMember<TestNoInvariant[5]>;
// CHECK-LABEL: define void @test_builtin_launder_member_array_no_invariant(
extern "C" void test_builtin_launder_member_array_no_invariant(WithMember<TestNoInvariant[5]> *p) {
// CHECK: entry
// CHECK-NOT: @llvm.launder.invariant.group
// CHECK: ret void
auto *d = __builtin_launder(p);
}
template struct WithMember<TestNoInvariant[5][2]>;
// CHECK-LABEL: define void @test_builtin_launder_member_array_nested_no_invariant(
extern "C" void test_builtin_launder_member_array_nested_no_invariant(WithMember<TestNoInvariant[5][2]> *p) {
// CHECK: entry
// CHECK-NOT: @llvm.launder.invariant.group
// CHECK: ret void
auto *d = __builtin_launder(p);
}
template <class T>
struct WithBase : T {};
template struct WithBase<TestNoInvariant>;
// CHECK-LABEL: define void @test_builtin_launder_base_no_invariant(
extern "C" void test_builtin_launder_base_no_invariant(WithBase<TestNoInvariant> *p) {
// CHECK: entry
// CHECK-NOT: @llvm.launder.invariant.group
// CHECK: ret void
auto *d = __builtin_launder(p);
}
template struct WithBase<TestVirtualFn>;
// CHECK-LABEL: define void @test_builtin_launder_base(
extern "C" void test_builtin_launder_base(WithBase<TestVirtualFn> *p) {
// CHECK: entry
// CHECK-NONSTRICT-NOT: @llvm.launder.invariant.group
// CHECK-STRICT: @llvm.launder.invariant.group
// CHECK: ret void
auto *d = __builtin_launder(p);
}
/// The test cases in this namespace technically need to be laundered according
/// to the language in the standard (ie they have const or reference subobjects)
/// but LLVM doesn't currently optimize on these cases -- so Clang emits
/// __builtin_launder as a nop.
///
/// NOTE: Adding optimizations for these cases later is an LTO ABI break. That's
/// probably OK for now -- but is something to keep in mind.
namespace pessimizing_cases {
struct TestConstMember {
const int x;
};
// CHECK-LABEL: define void @test_builtin_launder_const_member
extern "C" void test_builtin_launder_const_member(TestConstMember *p) {
// CHECK: entry
// CHECK-NOT: @llvm.launder.invariant.group
// CHECK: ret void
TestConstMember *d = __builtin_launder(p);
}
struct TestConstSubobject {
TestConstMember x;
};
// CHECK-LABEL: define void @test_builtin_launder_const_subobject
extern "C" void test_builtin_launder_const_subobject(TestConstSubobject *p) {
// CHECK: entry
// CHECK-NOT: @llvm.launder.invariant.group
// CHECK: ret void
TestConstSubobject *d = __builtin_launder(p);
}
struct TestConstObject {
const struct TestConstMember x;
};
// CHECK-LABEL: define void @test_builtin_launder_const_object
extern "C" void test_builtin_launder_const_object(TestConstObject *p) {
// CHECK: entry
// CHECK-NOT: @llvm.launder.invariant.group
// CHECK: ret void
TestConstObject *d = __builtin_launder(p);
}
struct TestReferenceMember {
int &x;
};
// CHECK-LABEL: define void @test_builtin_launder_reference_member
extern "C" void test_builtin_launder_reference_member(TestReferenceMember *p) {
// CHECK: entry
// CHECK-NOT: @llvm.launder.invariant.group
// CHECK: ret void
TestReferenceMember *d = __builtin_launder(p);
}
} // namespace pessimizing_cases

1
clang/test/Preprocessor/feature_tests.c
View File

@ -14,6 +14,7 @@
!__has_builtin(__builtin_convertvector) || \
!__has_builtin(__builtin_trap) || \
!__has_builtin(__c11_atomic_init) || \
!__has_builtin(__builtin_launder) || \
!__has_feature(attribute_analyzer_noreturn) || \
!__has_feature(attribute_overloadable)
#error Clang should have these

18
clang/test/Sema/builtins.c
View File

@ -258,6 +258,24 @@ char * Test20(char *p, const char *in, unsigned n)
return buf;
}
typedef void (fn_t)(int);
void test_builtin_launder(char *p, void *vp, const void *cvp,
const volatile int *ip, float *restrict fp,
fn_t *fn) {
__builtin_launder(); // expected-error {{too few arguments to function call, expected 1, have 0}}
__builtin_launder(p, p); // expected-error {{too many arguments to function call, expected 1, have 2}}
int x;
__builtin_launder(x); // expected-error {{non-pointer argument to '__builtin_launder' is not allowed}}
char *d = __builtin_launder(p);
__builtin_launder(vp); // expected-error {{void pointer argument to '__builtin_launder' is not allowed}}
__builtin_launder(cvp); // expected-error {{void pointer argument to '__builtin_launder' is not allowed}}
const volatile int *id = __builtin_launder(ip);
int *id2 = __builtin_launder(ip); // expected-warning {{discards qualifiers}}
float *fd = __builtin_launder(fp);
__builtin_launder(fn); // expected-error {{function pointer argument to '__builtin_launder' is not allowed}}
}
void test21(const int *ptr) {
__sync_fetch_and_add(ptr, 1); // expected-error{{address argument to atomic builtin cannot be const-qualified ('const int *' invalid)}}
__atomic_fetch_add(ptr, 1, 0); // expected-error {{address argument to atomic operation must be a pointer to non-const type ('const int *' invalid)}}

92
clang/test/SemaCXX/builtins.cpp
View File

@ -53,3 +53,95 @@ extern "C" int vfprintf(FILE *__restrict, const char *__restrict,
void synchronize_args() {
__sync_synchronize(0); // expected-error {{too many arguments}}
}
namespace test_launder {
#define TEST_TYPE(Ptr, Type) \
static_assert(__is_same(decltype(__builtin_launder(Ptr)), Type), "expected same type")
struct Dummy {};
using FnType = int(char);
using MemFnType = int (Dummy::*)(char);
using ConstMemFnType = int (Dummy::*)() const;
void foo() {}
void test_builtin_launder_diags(void *vp, const void *cvp, FnType *fnp,
MemFnType mfp, ConstMemFnType cmfp, int (&Arr)[5]) {
__builtin_launder(vp); // expected-error {{void pointer argument to '__builtin_launder' is not allowed}}
__builtin_launder(cvp); // expected-error {{void pointer argument to '__builtin_launder' is not allowed}}
__builtin_launder(fnp); // expected-error {{function pointer argument to '__builtin_launder' is not allowed}}
__builtin_launder(mfp); // expected-error {{non-pointer argument to '__builtin_launder' is not allowed}}
__builtin_launder(cmfp); // expected-error {{non-pointer argument to '__builtin_launder' is not allowed}}
(void)__builtin_launder(&fnp);
__builtin_launder(42); // expected-error {{non-pointer argument to '__builtin_launder' is not allowed}}
__builtin_launder(nullptr); // expected-error {{non-pointer argument to '__builtin_launder' is not allowed}}
__builtin_launder(foo); // expected-error {{function pointer argument to '__builtin_launder' is not allowed}}
(void)__builtin_launder(Arr);
}
void test_builtin_launder(char *p, const volatile int *ip, const float *&fp,
double *__restrict dp) {
int x;
__builtin_launder(x); // expected-error {{non-pointer argument to '__builtin_launder' is not allowed}}
TEST_TYPE(p, char*);
TEST_TYPE(ip, const volatile int*);
TEST_TYPE(fp, const float*);
TEST_TYPE(dp, double *__restrict);
char *d = __builtin_launder(p);
const volatile int *id = __builtin_launder(ip);
int *id2 = __builtin_launder(ip); // expected-error {{cannot initialize a variable of type 'int *' with an rvalue of type 'const volatile int *'}}
const float* fd = __builtin_launder(fp);
}
void test_launder_return_type(const int (&ArrayRef)[101], int (&MArrRef)[42][13],
void (**&FuncPtrRef)()) {
TEST_TYPE(ArrayRef, const int *);
TEST_TYPE(MArrRef, int(*)[13]);
TEST_TYPE(FuncPtrRef, void (**)());
}
template <class Tp>
constexpr Tp *test_constexpr_launder(Tp *tp) {
return __builtin_launder(tp);
}
constexpr int const_int = 42;
constexpr int const_int2 = 101;
constexpr const int *const_ptr = test_constexpr_launder(&const_int);
static_assert(&const_int == const_ptr, "");
static_assert(const_ptr != test_constexpr_launder(&const_int2), "");
void test_non_constexpr() {
constexpr int i = 42; // expected-note {{declared here}}
constexpr const int *ip = __builtin_launder(&i); // expected-error {{constexpr variable 'ip' must be initialized by a constant expression}}
// expected-note@-1 {{pointer to 'i' is not a constant expression}}
}
constexpr bool test_in_constexpr(const int &i) {
return (__builtin_launder(&i) == &i);
}
static_assert(test_in_constexpr(const_int), "");
void f() {
constexpr int i = 42;
static_assert(test_in_constexpr(i), "");
}
struct Incomplete; // expected-note {{forward declaration}}
struct IncompleteMember {
Incomplete &i;
};
void test_incomplete(Incomplete *i, IncompleteMember *im) {
// expected-error@+1 {{incomplete type 'test_launder::Incomplete' where a complete type is required}}
__builtin_launder(i);
__builtin_launder(&i); // OK
__builtin_launder(im); // OK
}
void test_noexcept(int *i) {
static_assert(noexcept(__builtin_launder(i)), "");
}
#undef TEST_TYPE
} // end namespace test_launder