ItaniumCXXABI.cpp source code [clang_source_code/lib/AST/ItaniumCXXABI.cpp]

1	//===------- ItaniumCXXABI.cpp - AST support for the Itanium C++ ABI ------===//
2	//
3	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4	// See https://llvm.org/LICENSE.txt for license information.
5	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6	//
7	//===----------------------------------------------------------------------===//
8	//
9	// This provides C++ AST support targeting the Itanium C++ ABI, which is
10	// documented at:
11	// http://www.codesourcery.com/public/cxx-abi/abi.html
12	// http://www.codesourcery.com/public/cxx-abi/abi-eh.html
13	//
14	// It also supports the closely-related ARM C++ ABI, documented at:
15	// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0041c/IHI0041C_cppabi.pdf
16	//
17	//===----------------------------------------------------------------------===//
18
19	#include "CXXABI.h"
20	#include "clang/AST/ASTContext.h"
21	#include "clang/AST/DeclCXX.h"
22	#include "clang/AST/MangleNumberingContext.h"
23	#include "clang/AST/RecordLayout.h"
24	#include "clang/AST/Type.h"
25	#include "clang/Basic/TargetInfo.h"
26	#include "llvm/ADT/iterator.h"
27
28	using namespace clang;
29
30	namespace {
31
32	/// According to Itanium C++ ABI 5.1.2:
33	/// the name of an anonymous union is considered to be
34	/// the name of the first named data member found by a pre-order,
35	/// depth-first, declaration-order walk of the data members of
36	/// the anonymous union.
37	/// If there is no such data member (i.e., if all of the data members
38	/// in the union are unnamed), then there is no way for a program to
39	/// refer to the anonymous union, and there is therefore no need to mangle its name.
40	///
41	/// Returns the name of anonymous union VarDecl or nullptr if it is not found.
42	static const IdentifierInfo *findAnonymousUnionVarDeclName(const VarDecl& VD) {
43	const RecordType *RT = VD.getType()->getAs<RecordType>();
44	(0) . __assert_fail ("RT && \"type of VarDecl is expected to be RecordType.\"", "/home/seafit/code_projects/clang_source/clang/lib/AST/ItaniumCXXABI.cpp", 44, __PRETTY_FUNCTION__))" file_link="../../../include/assert.h.html#88" macro="true">assert(RT && "type of VarDecl is expected to be RecordType.");
45	(0) . __assert_fail ("RT->getDecl()->isUnion() && \"RecordType is expected to be a union.\"", "/home/seafit/code_projects/clang_source/clang/lib/AST/ItaniumCXXABI.cpp", 45, __PRETTY_FUNCTION__))" file_link="../../../include/assert.h.html#88" macro="true">assert(RT->getDecl()->isUnion() && "RecordType is expected to be a union.");
46	if (const FieldDecl *FD = RT->getDecl()->findFirstNamedDataMember()) {
47	return FD->getIdentifier();
48	}
49
50	return nullptr;
51	}
52
53	/// The name of a decomposition declaration.
54	struct DecompositionDeclName {
55	using BindingArray = ArrayRef<const BindingDecl*>;
56
57	/// Representative example of a set of bindings with these names.
58	BindingArray Bindings;
59
60	/// Iterators over the sequence of identifiers in the name.
61	struct Iterator
62	: llvm::iterator_adaptor_base<Iterator, BindingArray::const_iterator,
63	std::random_access_iterator_tag,
64	const IdentifierInfo *> {
65	Iterator(BindingArray::const_iterator It) : iterator_adaptor_base(It) {}
66	const IdentifierInfo operator() const {
67	return (*this->I)->getIdentifier();
68	}
69	};
70	Iterator begin() const { return Iterator(Bindings.begin()); }
71	Iterator end() const { return Iterator(Bindings.end()); }
72	};
73	}
74
75	namespace llvm {
76	template<>
77	struct DenseMapInfo<DecompositionDeclName> {
78	using ArrayInfo = llvm::DenseMapInfo<ArrayRef<const BindingDecl*>>;
79	using IdentInfo = llvm::DenseMapInfo<const IdentifierInfo*>;
80	static DecompositionDeclName getEmptyKey() {
81	return {ArrayInfo::getEmptyKey()};
82	}
83	static DecompositionDeclName getTombstoneKey() {
84	return {ArrayInfo::getTombstoneKey()};
85	}
86	static unsigned getHashValue(DecompositionDeclName Key) {
87	assert(!isEqual(Key, getEmptyKey()) && !isEqual(Key, getTombstoneKey()));
88	return llvm::hash_combine_range(Key.begin(), Key.end());
89	}
90	static bool isEqual(DecompositionDeclName LHS, DecompositionDeclName RHS) {
91	if (ArrayInfo::isEqual(LHS.Bindings, ArrayInfo::getEmptyKey()))
92	return ArrayInfo::isEqual(RHS.Bindings, ArrayInfo::getEmptyKey());
93	if (ArrayInfo::isEqual(LHS.Bindings, ArrayInfo::getTombstoneKey()))
94	return ArrayInfo::isEqual(RHS.Bindings, ArrayInfo::getTombstoneKey());
95	return LHS.Bindings.size() == RHS.Bindings.size() &&
96	std::equal(LHS.begin(), LHS.end(), RHS.begin());
97	}
98	};
99	}
100
101	namespace {
102
103	/// Keeps track of the mangled names of lambda expressions and block
104	/// literals within a particular context.
105	class ItaniumNumberingContext : public MangleNumberingContext {
106	llvm::DenseMap<const Type *, unsigned> ManglingNumbers;
107	llvm::DenseMap<const IdentifierInfo *, unsigned> VarManglingNumbers;
108	llvm::DenseMap<const IdentifierInfo *, unsigned> TagManglingNumbers;
109	llvm::DenseMap<DecompositionDeclName, unsigned>
110	DecompsitionDeclManglingNumbers;
111
112	public:
113	unsigned getManglingNumber(const CXXMethodDecl *CallOperator) override {
114	const FunctionProtoType *Proto =
115	CallOperator->getType()->getAs<FunctionProtoType>();
116	ASTContext &Context = CallOperator->getASTContext();
117
118	FunctionProtoType::ExtProtoInfo EPI;
119	EPI.Variadic = Proto->isVariadic();
120	QualType Key =
121	Context.getFunctionType(Context.VoidTy, Proto->getParamTypes(), EPI);
122	Key = Context.getCanonicalType(Key);
123	return ++ManglingNumbers[Key->castAs<FunctionProtoType>()];
124	}
125
126	unsigned getManglingNumber(const BlockDecl *BD) override {
127	const Type *Ty = nullptr;
128	return ++ManglingNumbers[Ty];
129	}
130
131	unsigned getStaticLocalNumber(const VarDecl *VD) override {
132	return 0;
133	}
134
135	/// Variable decls are numbered by identifier.
136	unsigned getManglingNumber(const VarDecl *VD, unsigned) override {
137	if (auto *DD = dyn_cast<DecompositionDecl>(VD)) {
138	DecompositionDeclName Name{DD->bindings()};
139	return ++DecompsitionDeclManglingNumbers[Name];
140	}
141
142	const IdentifierInfo *Identifier = VD->getIdentifier();
143	if (!Identifier) {
144	// VarDecl without an identifier represents an anonymous union
145	// declaration.
146	Identifier = findAnonymousUnionVarDeclName(*VD);
147	}
148	return ++VarManglingNumbers[Identifier];
149	}
150
151	unsigned getManglingNumber(const TagDecl *TD, unsigned) override {
152	return ++TagManglingNumbers[TD->getIdentifier()];
153	}
154	};
155
156	class ItaniumCXXABI : public CXXABI {
157	protected:
158	ASTContext &Context;
159	public:
160	ItaniumCXXABI(ASTContext &Ctx) : Context(Ctx) { }
161
162	MemberPointerInfo
163	getMemberPointerInfo(const MemberPointerType *MPT) const override {
164	const TargetInfo &Target = Context.getTargetInfo();
165	TargetInfo::IntType PtrDiff = Target.getPtrDiffType(0);
166	MemberPointerInfo MPI;
167	MPI.Width = Target.getTypeWidth(PtrDiff);
168	MPI.Align = Target.getTypeAlign(PtrDiff);
169	MPI.HasPadding = false;
170	if (MPT->isMemberFunctionPointer())
171	MPI.Width *= 2;
172	return MPI;
173	}
174
175	CallingConv getDefaultMethodCallConv(bool isVariadic) const override {
176	const llvm::Triple &T = Context.getTargetInfo().getTriple();
177	if (!isVariadic && T.isWindowsGNUEnvironment() &&
178	T.getArch() == llvm::Triple::x86)
179	return CC_X86ThisCall;
180	return CC_C;
181	}
182
183	// We cheat and just check that the class has a vtable pointer, and that it's
184	// only big enough to have a vtable pointer and nothing more (or less).
185	bool isNearlyEmpty(const CXXRecordDecl *RD) const override {
186
187	// Check that the class has a vtable pointer.
188	if (!RD->isDynamicClass())
189	return false;
190
191	const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
192	CharUnits PointerSize =
193	Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
194	return Layout.getNonVirtualSize() == PointerSize;
195	}
196
197	const CXXConstructorDecl *
198	getCopyConstructorForExceptionObject(CXXRecordDecl *RD) override {
199	return nullptr;
200	}
201
202	void addCopyConstructorForExceptionObject(CXXRecordDecl *RD,
203	CXXConstructorDecl *CD) override {}
204
205	void addTypedefNameForUnnamedTagDecl(TagDecl *TD,
206	TypedefNameDecl *DD) override {}
207
208	TypedefNameDecl getTypedefNameForUnnamedTagDecl(const TagDecl TD) override {
209	return nullptr;
210	}
211
212	void addDeclaratorForUnnamedTagDecl(TagDecl *TD,
213	DeclaratorDecl *DD) override {}
214
215	DeclaratorDecl getDeclaratorForUnnamedTagDecl(const TagDecl TD) override {
216	return nullptr;
217	}
218
219	std::unique_ptr<MangleNumberingContext>
220	createMangleNumberingContext() const override {
221	return llvm::make_unique<ItaniumNumberingContext>();
222	}
223	};
224	}
225
226	CXXABI *clang::CreateItaniumCXXABI(ASTContext &Ctx) {
227	return new ItaniumCXXABI(Ctx);
228	}
229

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