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MS ABI: Update the thunk linkage computation

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As suggested by Reid:

 - class has GVA_Internal linkage -> internal
 - thunk has return adjustment -> weak_odr, to handle evil corner case [1]
 - all other normal methods -> linkonce_odr

 1. Evil corner case:

  struct Incomplete;
  struct A { int a; virtual A *bar(); };
  struct B { int b; virtual B *foo(Incomplete); };
  struct C : A, B { int c; virtual C *foo(Incomplete); };
  C c;

Here, the thunk for C::foo() will be emitted when C::foo() is defined, which
might be in a different translation unit, so it needs to be weak_odr.

Differential Revision: http://reviews.llvm.org/D3992

llvm-svn: 210368
This commit is contained in:
Hans Wennborg 2014-06-06 20:04:01 +00:00
parent 0766ae08e5
commit c94391d3bf
9 changed files with 41 additions and 17 deletions
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3
clang/lib/CodeGen/CGCXXABI.h
View File

@ -359,7 +359,8 @@ public:
/// base tables.
virtual void emitVirtualInheritanceTables(const CXXRecordDecl *RD) = 0;
virtual void setThunkLinkage(llvm::Function *Thunk, bool ForVTable) = 0;
virtual void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,
GlobalDecl GD, bool ReturnAdjustment) = 0;
virtual llvm::Value *performThisAdjustment(CodeGenFunction &CGF,
llvm::Value *This,

6
clang/lib/CodeGen/CGVTables.cpp
View File

@ -382,12 +382,14 @@ void CodeGenVTables::emitThunk(GlobalDecl GD, const ThunkInfo &Thunk,
// FIXME: Do something better here; GenerateVarArgsThunk is extremely ugly.
if (!UseAvailableExternallyLinkage) {
CodeGenFunction(CGM).GenerateVarArgsThunk(ThunkFn, FnInfo, GD, Thunk);
CGM.getCXXABI().setThunkLinkage(ThunkFn, ForVTable);
CGM.getCXXABI().setThunkLinkage(ThunkFn, ForVTable, GD,
!Thunk.Return.isEmpty());
}
} else {
// Normal thunk body generation.
CodeGenFunction(CGM).GenerateThunk(ThunkFn, FnInfo, GD, Thunk);
CGM.getCXXABI().setThunkLinkage(ThunkFn, ForVTable);
CGM.getCXXABI().setThunkLinkage(ThunkFn, ForVTable, GD,
!Thunk.Return.isEmpty());
}
}

3
clang/lib/CodeGen/ItaniumCXXABI.cpp
View File

@ -174,7 +174,8 @@ public:
void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override;
void setThunkLinkage(llvm::Function *Thunk, bool ForVTable) override {
void setThunkLinkage(llvm::Function *Thunk, bool ForVTable, GlobalDecl GD,
bool ReturnAdjustment) override {
// Allow inlining of thunks by emitting them with available_externally
// linkage together with vtables when needed.
if (ForVTable)

15
clang/lib/CodeGen/MicrosoftCXXABI.cpp
View File

@ -201,11 +201,20 @@ public:
void emitVBTableDefinition(const VPtrInfo &VBT, const CXXRecordDecl *RD,
llvm::GlobalVariable *GV) const;
void setThunkLinkage(llvm::Function *Thunk, bool ForVTable) override {
Thunk->setLinkage(llvm::GlobalValue::WeakAnyLinkage);
void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,
GlobalDecl GD, bool ReturnAdjustment) override {
// Never dllimport/dllexport thunks.
Thunk->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
GVALinkage Linkage =
getContext().GetGVALinkageForFunction(cast<FunctionDecl>(GD.getDecl()));
if (Linkage == GVA_Internal)
Thunk->setLinkage(llvm::GlobalValue::InternalLinkage);
else if (ReturnAdjustment)
Thunk->setLinkage(llvm::GlobalValue::WeakODRLinkage);
else
Thunk->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
}
llvm::Value *performThisAdjustment(CodeGenFunction &CGF, llvm::Value *This,

2
clang/test/CodeGenCXX/dllimport.cpp
View File

@ -566,7 +566,7 @@ namespace DontUseDtorAlias {
namespace Vtordisp {
// Don't dllimport the vtordisp.
// MO1-DAG: define weak x86_thiscallcc void @"\01?f@?$C@D@Vtordisp@@$4PPPPPPPM@A@AEXXZ"
// MO1-DAG: define linkonce_odr x86_thiscallcc void @"\01?f@?$C@D@Vtordisp@@$4PPPPPPPM@A@AEXXZ"
class Base {
virtual void f() {}

2
clang/test/CodeGenCXX/microsoft-abi-structors.cpp
View File

@ -153,7 +153,7 @@ C::~C() {
void foo() {
C c;
}
// DTORS2-LABEL: define weak x86_thiscallcc void @"\01??_EC@dtor_in_second_nvbase@@W3AEPAXI@Z"
// DTORS2-LABEL: define linkonce_odr x86_thiscallcc void @"\01??_EC@dtor_in_second_nvbase@@W3AEPAXI@Z"
// DTORS2: (%"struct.dtor_in_second_nvbase::C"* %this, i32 %should_call_delete)
// Do an adjustment from B* to C*.
// DTORS2: getelementptr i8* %{{.*}}, i32 -4

19
clang/test/CodeGenCXX/microsoft-abi-thunks.cpp
View File

@ -61,13 +61,13 @@ struct C : A, B {
C::C() {} // Emits vftable and forces thunk generation.
// CODEGEN-LABEL: define weak x86_thiscallcc void @"\01??_EC@@W3AEPAXI@Z"(%struct.C* %this, i32 %should_call_delete)
// CODEGEN-LABEL: define linkonce_odr x86_thiscallcc void @"\01??_EC@@W3AEPAXI@Z"(%struct.C* %this, i32 %should_call_delete)
// CODEGEN: getelementptr i8* {{.*}}, i32 -4
// FIXME: should actually call _EC, not _GC.
// CODEGEN: call x86_thiscallcc void @"\01??_GC@@UAEPAXI@Z"
// CODEGEN: ret
// CODEGEN-LABEL: define weak x86_thiscallcc void @"\01?public_f@C@@W3AEXXZ"(%struct.C*
// CODEGEN-LABEL: define linkonce_odr x86_thiscallcc void @"\01?public_f@C@@W3AEXXZ"(%struct.C*
// CODEGEN: getelementptr i8* {{.*}}, i32 -4
// CODEGEN: call x86_thiscallcc void @"\01?public_f@C@@UAEXXZ"(%struct.C*
// CODEGEN: ret
@ -91,7 +91,7 @@ struct E : D {
E::E() {} // Emits vftable and forces thunk generation.
// CODEGEN-LABEL: define weak x86_thiscallcc %struct.C* @"\01?goo@E@@QAEPAUB@@XZ"
// CODEGEN-LABEL: define weak_odr x86_thiscallcc %struct.C* @"\01?goo@E@@QAEPAUB@@XZ"
// CODEGEN: call x86_thiscallcc %struct.C* @"\01?goo@E@@UAEPAUC@@XZ"
// CODEGEN: getelementptr inbounds i8* {{.*}}, i32 4
// CODEGEN: ret
@ -124,7 +124,7 @@ struct I : D {
I::I() {} // Emits vftable and forces thunk generation.
// CODEGEN-LABEL: define weak x86_thiscallcc %struct.{{[BF]}}* @"\01?goo@I@@QAEPAUB@@XZ"
// CODEGEN-LABEL: define weak_odr x86_thiscallcc %struct.{{[BF]}}* @"\01?goo@I@@QAEPAUB@@XZ"
// CODEGEN: %[[ORIG_RET:.*]] = call x86_thiscallcc %struct.F* @"\01?goo@I@@UAEPAUF@@XZ"
// CODEGEN: %[[ORIG_RET_i8:.*]] = bitcast %struct.F* %[[ORIG_RET]] to i8*
// CODEGEN: %[[VBPTR_i8:.*]] = getelementptr inbounds i8* %[[ORIG_RET_i8]], i32 4
@ -152,3 +152,14 @@ struct C : A, B {
};
C c;
}
namespace {
struct E : D {
E();
virtual C* goo();
};
E::E() {}
E e;
// Class with internal linkage has internal linkage thunks.
// CODEGEN: define internal x86_thiscallcc %struct.C* @"\01?goo@E@?A@@QAEPAUB@@XZ"
}

6
clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance-vtordisps.cpp
View File

@ -23,7 +23,7 @@ struct D : virtual C {
D::D() {} // Forces vftable emission.
// CHECK-LABEL: define weak x86_thiscallcc void @"\01?f@D@@$4PPPPPPPM@A@AEXXZ"
// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@D@@$4PPPPPPPM@A@AEXXZ"
// CHECK: %[[ECX:.*]] = load %struct.D** %{{.*}}
// CHECK: %[[ECX_i8:.*]] = bitcast %struct.D* %[[ECX]] to i8*
// CHECK: %[[VTORDISP_PTR_i8:.*]] = getelementptr i8* %[[ECX_i8]], i32 -4
@ -34,7 +34,7 @@ D::D() {} // Forces vftable emission.
// CHECK: call x86_thiscallcc void @"\01?f@D@@UAEXXZ"(i8* %[[ADJUSTED_i8]])
// CHECK: ret void
// CHECK-LABEL: define weak x86_thiscallcc void @"\01?f@D@@$4PPPPPPPI@3AEXXZ"
// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@D@@$4PPPPPPPI@3AEXXZ"
// CHECK: %[[ECX:.*]] = load %struct.D** %{{.*}}
// CHECK: %[[ECX_i8:.*]] = bitcast %struct.D* %[[ECX]] to i8*
// CHECK: %[[VTORDISP_PTR_i8:.*]] = getelementptr i8* %[[ECX_i8]], i32 -8
@ -63,7 +63,7 @@ struct G : virtual F, virtual E {
G::G() {} // Forces vftable emission.
// CHECK-LABEL: define weak x86_thiscallcc void @"\01?f@E@@$R4BA@M@PPPPPPPM@7AEXXZ"(i8*)
// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@E@@$R4BA@M@PPPPPPPM@7AEXXZ"(i8*)
// CHECK: %[[ECX:.*]] = load %struct.E** %{{.*}}
// CHECK: %[[ECX_i8:.*]] = bitcast %struct.E* %[[ECX]] to i8*
// CHECK: %[[VTORDISP_PTR_i8:.*]] = getelementptr i8* %[[ECX_i8]], i32 -4

2
clang/test/CodeGenCXX/microsoft-abi-vtables-virtual-inheritance.cpp
View File

@ -145,7 +145,7 @@ struct X: virtual C {
// MANGLING-DAG: @"\01??_7X@Test4@@6B@"
// Also check the mangling of the thunk.
// MANGLING-DAG: define weak x86_thiscallcc void @"\01?f@C@@WPPPPPPPI@AEXXZ"
// MANGLING-DAG: define linkonce_odr x86_thiscallcc void @"\01?f@C@@WPPPPPPPI@AEXXZ"
};
X::X() {}