Index: lib/CodeGen/CGCXXABI.h
===================================================================
--- lib/CodeGen/CGCXXABI.h
+++ lib/CodeGen/CGCXXABI.h
@@ -111,6 +111,10 @@
RAA_Indirect
};
+ /// Returns true if C++ allows us to copy the memory of an object of type RD
+ /// when it is passed as an argument.
+ bool canCopyArgument(const CXXRecordDecl *RD) const;
+
/// Returns how an argument of the given record type should be passed.
virtual RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const = 0;
Index: lib/CodeGen/CGCXXABI.cpp
===================================================================
--- lib/CodeGen/CGCXXABI.cpp
+++ lib/CodeGen/CGCXXABI.cpp
@@ -28,6 +28,37 @@
<< S;
}
+bool CGCXXABI::canCopyArgument(const CXXRecordDecl *RD) const {
+ // If RD has a non-trivial move or copy constructor, we cannot copy the
+ // argument.
+ if (RD->hasNonTrivialCopyConstructor() || RD->hasNonTrivialMoveConstructor())
+ return false;
+
+ // If RD has a non-trivial destructor, we cannot copy the argument.
+ if (RD->hasNonTrivialDestructor())
+ return false;
+
+ // We can only copy the argument if there exists at least one trivial,
+ // non-deleted copy or move constructor.
+ // FIXME: This assumes that all lazily declared copy and move constructors are
+ // not deleted. This assumption might not be true in some corner cases.
+ bool CopyOrMoveDeleted = false;
+ for (const CXXConstructorDecl *CD : RD->ctors()) {
+ if (CD->isCopyConstructor() || CD->isMoveConstructor()) {
+ assert(CD->isTrivial());
+ // We had at least one undeleted trivial copy or move ctor. Return
+ // directly.
+ if (!CD->isDeleted())
+ return true;
+ CopyOrMoveDeleted = true;
+ }
+ }
+
+ // If all trivial copy and move constructors are deleted, we cannot copy the
+ // argument.
+ return !CopyOrMoveDeleted;
+}
+
llvm::Constant *CGCXXABI::GetBogusMemberPointer(QualType T) {
return llvm::Constant::getNullValue(CGM.getTypes().ConvertType(T));
}
Index: lib/CodeGen/ItaniumCXXABI.cpp
===================================================================
--- lib/CodeGen/ItaniumCXXABI.cpp
+++ lib/CodeGen/ItaniumCXXABI.cpp
@@ -59,9 +59,8 @@
}
RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override {
- // Structures with either a non-trivial destructor or a non-trivial
- // copy constructor are always indirect.
- if (!RD->hasTrivialDestructor() || RD->hasNonTrivialCopyConstructor())
+ // If C++ prohibits us from making a copy, pass by address.
+ if (!canCopyArgument(RD))
return RAA_Indirect;
return RAA_Default;
}
Index: lib/CodeGen/MicrosoftCXXABI.cpp
===================================================================
--- lib/CodeGen/MicrosoftCXXABI.cpp
+++ lib/CodeGen/MicrosoftCXXABI.cpp
@@ -407,19 +407,46 @@
return RAA_Default;
case llvm::Triple::x86:
- // 32-bit x86 constructs non-trivial objects directly in outgoing argument
- // slots. LLVM uses the inalloca attribute to implement this.
- if (RD->hasNonTrivialCopyConstructor() || RD->hasNonTrivialDestructor())
+ // All record arguments are passed in memory on x86. Decide whether to
+ // construct the object directly in argument memory, or to construct the
+ // argument elsewhere and copy the bytes during the call.
+
+ // If C++ prohibits us from making a copy, construct the arguments directly
+ // into argument memory.
+ if (!canCopyArgument(RD))
return RAA_DirectInMemory;
+
+ // Otherwise, construct the argument into a temporary and copy the bytes
+ // into the outgoing argument memory.
return RAA_Default;
case llvm::Triple::x86_64:
// Win64 passes objects with non-trivial copy ctors indirectly.
if (RD->hasNonTrivialCopyConstructor())
return RAA_Indirect;
+
// Win64 passes objects larger than 8 bytes indirectly.
if (getContext().getTypeSize(RD->getTypeForDecl()) > 64)
return RAA_Indirect;
+
+ // We have a trivial copy constructor or no copy constructors, but we have
+ // to make sure it isn't deleted.
+ bool CopyDeleted = false;
+ for (const CXXConstructorDecl *CD : RD->ctors()) {
+ if (CD->isCopyConstructor()) {
+ assert(CD->isTrivial());
+ // We had at least one undeleted trivial copy ctor. Return directly.
+ if (!CD->isDeleted())
+ return RAA_Default;
+ CopyDeleted = true;
+ }
+ }
+
+ // The trivial copy constructor was deleted. Return indirectly.
+ if (CopyDeleted)
+ return RAA_Indirect;
+
+ // There were no copy ctors. Return in RAX.
return RAA_Default;
}
Index: test/CodeGenCXX/uncopyable-args.cpp
===================================================================
--- /dev/null
+++ test/CodeGenCXX/uncopyable-args.cpp
@@ -0,0 +1,200 @@
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-windows-msvc -emit-llvm -o - %s | FileCheck %s -check-prefix=WIN64
+
+namespace trivial {
+// Trivial structs should be passed directly.
+struct A {
+ void *p;
+};
+void foo(A);
+void bar() {
+ foo({});
+}
+// CHECK-LABEL: define void @_ZN7trivial3barEv()
+// CHECK: alloca %"struct.trivial::A"
+// CHECK: load i8**
+// CHECK: call void @_ZN7trivial3fooENS_1AE(i8* %{{.*}})
+// CHECK-LABEL: declare void @_ZN7trivial3fooENS_1AE(i8*)
+
+// WIN64-LABEL: declare void @"\01?foo@trivial@@YAXUA@1@@Z"(i64)
+}
+
+namespace default_ctor {
+struct A {
+ A();
+ void *p;
+};
+void foo(A);
+void bar() {
+ // Core issue 1590. We can pass this type in registers, even though C++
+ // normally doesn't permit copies when using braced initialization.
+ foo({});
+}
+// CHECK-LABEL: define void @_ZN12default_ctor3barEv()
+// CHECK: alloca %"struct.default_ctor::A"
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK: load i8**
+// CHECK: call void @_ZN12default_ctor3fooENS_1AE(i8* %{{.*}})
+// CHECK-LABEL: declare void @_ZN12default_ctor3fooENS_1AE(i8*)
+
+// WIN64-LABEL: declare void @"\01?foo@default_ctor@@YAXUA@1@@Z"(i64)
+}
+
+namespace move_ctor {
+// The presence of a move constructor implicitly deletes the trivial copy ctor
+// and means that we have to pass this struct by address.
+struct A {
+ A();
+ A(A &&o);
+ void *p;
+};
+void foo(A);
+void bar() {
+ foo({});
+}
+// CHECK-LABEL: define void @_ZN9move_ctor3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK-NOT: call
+// CHECK: call void @_ZN9move_ctor3fooENS_1AE(%"struct.move_ctor::A"* %{{.*}})
+// CHECK-LABEL: declare void @_ZN9move_ctor3fooENS_1AE(%"struct.move_ctor::A"*)
+
+// WIN64-LABEL: declare void @"\01?foo@move_ctor@@YAXUA@1@@Z"(%"struct.move_ctor::A"*)
+}
+
+namespace all_deleted {
+struct A {
+ A();
+ A(const A &o) = delete;
+ A(A &&o) = delete;
+ void *p;
+};
+void foo(A);
+void bar() {
+ foo({});
+}
+// CHECK-LABEL: define void @_ZN11all_deleted3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK-NOT call
+// CHECK: call void @_ZN11all_deleted3fooENS_1AE(%"struct.all_deleted::A"* %{{.*}})
+// CHECK-LABEL: declare void @_ZN11all_deleted3fooENS_1AE(%"struct.all_deleted::A"*)
+
+// WIN64-LABEL: declare void @"\01?foo@all_deleted@@YAXUA@1@@Z"(%"struct.all_deleted::A"*)
+}
+
+namespace implicitly_deleted {
+struct A {
+ A();
+ A &operator=(A &&o);
+ void *p;
+};
+void foo(A);
+void bar() {
+ foo({});
+}
+// CHECK-LABEL: define void @_ZN18implicitly_deleted3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK-NOT call
+// CHECK: call void @_ZN18implicitly_deleted3fooENS_1AE(%"struct.implicitly_deleted::A"* %{{.*}})
+// CHECK-LABEL: declare void @_ZN18implicitly_deleted3fooENS_1AE(%"struct.implicitly_deleted::A"*)
+
+// WIN64-LABEL: declare void @"\01?foo@implicitly_deleted@@YAXUA@1@@Z"(%"struct.implicitly_deleted::A"*)
+}
+
+namespace one_deleted {
+struct A {
+ A();
+ A(A &&o) = delete;
+ void *p;
+};
+void foo(A);
+void bar() {
+ foo({});
+}
+// CHECK-LABEL: define void @_ZN11one_deleted3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK-NOT call
+// CHECK: call void @_ZN11one_deleted3fooENS_1AE(%"struct.one_deleted::A"* %{{.*}})
+// CHECK-LABEL: declare void @_ZN11one_deleted3fooENS_1AE(%"struct.one_deleted::A"*)
+
+// WIN64-LABEL: declare void @"\01?foo@one_deleted@@YAXUA@1@@Z"(%"struct.one_deleted::A"*)
+}
+
+namespace copy_defaulted {
+struct A {
+ A();
+ A(const A &o) = default;
+ A(A &&o) = delete;
+ void *p;
+};
+void foo(A);
+void bar() {
+ foo({});
+}
+// CHECK-LABEL: define void @_ZN14copy_defaulted3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK: load i8**
+// CHECK: call void @_ZN14copy_defaulted3fooENS_1AE(i8* %{{.*}})
+// CHECK-LABEL: declare void @_ZN14copy_defaulted3fooENS_1AE(i8*)
+
+// WIN64-LABEL: declare void @"\01?foo@copy_defaulted@@YAXUA@1@@Z"(i64)
+}
+
+namespace move_defaulted {
+struct A {
+ A();
+ A(const A &o) = delete;
+ A(A &&o) = default;
+ void *p;
+};
+void foo(A);
+void bar() {
+ foo({});
+}
+// CHECK-LABEL: define void @_ZN14move_defaulted3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK: load i8**
+// CHECK: call void @_ZN14move_defaulted3fooENS_1AE(i8* %{{.*}})
+// CHECK-LABEL: declare void @_ZN14move_defaulted3fooENS_1AE(i8*)
+
+// WIN64-LABEL: declare void @"\01?foo@move_defaulted@@YAXUA@1@@Z"(%"struct.move_defaulted::A"*)
+}
+
+namespace trivial_defaulted {
+struct A {
+ A();
+ A(const A &o) = default;
+ void *p;
+};
+void foo(A);
+void bar() {
+ foo({});
+}
+// CHECK-LABEL: define void @_ZN17trivial_defaulted3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK: load i8**
+// CHECK: call void @_ZN17trivial_defaulted3fooENS_1AE(i8* %{{.*}})
+// CHECK-LABEL: declare void @_ZN17trivial_defaulted3fooENS_1AE(i8*)
+
+// WIN64-LABEL: declare void @"\01?foo@trivial_defaulted@@YAXUA@1@@Z"(i64)
+}
+
+namespace two_copy_ctors {
+struct A {
+ A();
+ A(const A &) = default;
+ A(const A &, int = 0);
+ void *p;
+};
+struct B : A {};
+
+void foo(B);
+void bar() {
+ foo({});
+}
+// CHECK-LABEL: define void @_ZN14two_copy_ctors3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK: call void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"* %{{.*}})
+// CHECK-LABEL: declare void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"*)
+
+// WIN64-LABEL: declare void @"\01?foo@two_copy_ctors@@YAXUB@1@@Z"(%"struct.two_copy_ctors::B"*)
+}