1//==- CGObjCRuntime.cpp - Interface to Shared Objective-C Runtime Features ==//
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 abstract class defines the interface for Objective-C runtime-specific
10// code generation. It provides some concrete helper methods for functionality
11// shared between all (or most) of the Objective-C runtimes supported by clang.
12//
13//===----------------------------------------------------------------------===//
14
15#include "CGObjCRuntime.h"
16#include "CGCXXABI.h"
17#include "CGCleanup.h"
18#include "CGRecordLayout.h"
19#include "CodeGenFunction.h"
20#include "CodeGenModule.h"
21#include "clang/AST/RecordLayout.h"
22#include "clang/AST/StmtObjC.h"
23#include "clang/CodeGen/CGFunctionInfo.h"
24#include "clang/CodeGen/CodeGenABITypes.h"
25#include "llvm/Support/SaveAndRestore.h"
26
27using namespace clang;
28using namespace CodeGen;
29
30uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
31 const ObjCInterfaceDecl *OID,
32 const ObjCIvarDecl *Ivar) {
33 return CGM.getContext().lookupFieldBitOffset(OID, nullptr, Ivar) /
34 CGM.getContext().getCharWidth();
35}
36
37uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
38 const ObjCImplementationDecl *OID,
39 const ObjCIvarDecl *Ivar) {
40 return CGM.getContext().lookupFieldBitOffset(OID->getClassInterface(), OID,
41 Ivar) /
42 CGM.getContext().getCharWidth();
43}
44
45unsigned CGObjCRuntime::ComputeBitfieldBitOffset(
46 CodeGen::CodeGenModule &CGM,
47 const ObjCInterfaceDecl *ID,
48 const ObjCIvarDecl *Ivar) {
49 return CGM.getContext().lookupFieldBitOffset(ID, ID->getImplementation(),
50 Ivar);
51}
52
53LValue CGObjCRuntime::EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF,
54 const ObjCInterfaceDecl *OID,
55 llvm::Value *BaseValue,
56 const ObjCIvarDecl *Ivar,
57 unsigned CVRQualifiers,
58 llvm::Value *Offset) {
59 // Compute (type*) ( (char *) BaseValue + Offset)
60 QualType InterfaceTy{OID->getTypeForDecl(), 0};
61 QualType ObjectPtrTy =
62 CGF.CGM.getContext().getObjCObjectPointerType(InterfaceTy);
63 QualType IvarTy =
64 Ivar->getUsageType(ObjectPtrTy).withCVRQualifiers(CVRQualifiers);
65 llvm::Type *LTy = CGF.CGM.getTypes().ConvertTypeForMem(IvarTy);
66 llvm::Value *V = CGF.Builder.CreateBitCast(BaseValue, CGF.Int8PtrTy);
67 V = CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, V, Offset, "add.ptr");
68
69 if (!Ivar->isBitField()) {
70 V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
71 LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
72 return LV;
73 }
74
75 // We need to compute an access strategy for this bit-field. We are given the
76 // offset to the first byte in the bit-field, the sub-byte offset is taken
77 // from the original layout. We reuse the normal bit-field access strategy by
78 // treating this as an access to a struct where the bit-field is in byte 0,
79 // and adjust the containing type size as appropriate.
80 //
81 // FIXME: Note that currently we make a very conservative estimate of the
82 // alignment of the bit-field, because (a) it is not clear what guarantees the
83 // runtime makes us, and (b) we don't have a way to specify that the struct is
84 // at an alignment plus offset.
85 //
86 // Note, there is a subtle invariant here: we can only call this routine on
87 // non-synthesized ivars but we may be called for synthesized ivars. However,
88 // a synthesized ivar can never be a bit-field, so this is safe.
89 uint64_t FieldBitOffset =
90 CGF.CGM.getContext().lookupFieldBitOffset(OID, nullptr, Ivar);
91 uint64_t BitOffset = FieldBitOffset % CGF.CGM.getContext().getCharWidth();
92 uint64_t AlignmentBits = CGF.CGM.getTarget().getCharAlign();
93 uint64_t BitFieldSize = Ivar->getBitWidthValue(CGF.getContext());
94 CharUnits StorageSize = CGF.CGM.getContext().toCharUnitsFromBits(
95 llvm::alignTo(BitOffset + BitFieldSize, AlignmentBits));
96 CharUnits Alignment = CGF.CGM.getContext().toCharUnitsFromBits(AlignmentBits);
97
98 // Allocate a new CGBitFieldInfo object to describe this access.
99 //
100 // FIXME: This is incredibly wasteful, these should be uniqued or part of some
101 // layout object. However, this is blocked on other cleanups to the
102 // Objective-C code, so for now we just live with allocating a bunch of these
103 // objects.
104 CGBitFieldInfo *Info = new (CGF.CGM.getContext()) CGBitFieldInfo(
105 CGBitFieldInfo::MakeInfo(CGF.CGM.getTypes(), Ivar, BitOffset, BitFieldSize,
106 CGF.CGM.getContext().toBits(StorageSize),
107 CharUnits::fromQuantity(0)));
108
109 Address Addr(V, Alignment);
110 Addr = CGF.Builder.CreateElementBitCast(Addr,
111 llvm::Type::getIntNTy(CGF.getLLVMContext(),
112 Info->StorageSize));
113 return LValue::MakeBitfield(Addr, *Info, IvarTy,
114 LValueBaseInfo(AlignmentSource::Decl),
115 TBAAAccessInfo());
116}
117
118namespace {
119 struct CatchHandler {
120 const VarDecl *Variable;
121 const Stmt *Body;
122 llvm::BasicBlock *Block;
123 llvm::Constant *TypeInfo;
124 /// Flags used to differentiate cleanups and catchalls in Windows SEH
125 unsigned Flags;
126 };
127
128 struct CallObjCEndCatch final : EHScopeStack::Cleanup {
129 CallObjCEndCatch(bool MightThrow, llvm::FunctionCallee Fn)
130 : MightThrow(MightThrow), Fn(Fn) {}
131 bool MightThrow;
132 llvm::FunctionCallee Fn;
133
134 void Emit(CodeGenFunction &CGF, Flags flags) override {
135 if (MightThrow)
136 CGF.EmitRuntimeCallOrInvoke(Fn);
137 else
138 CGF.EmitNounwindRuntimeCall(Fn);
139 }
140 };
141}
142
143void CGObjCRuntime::EmitTryCatchStmt(CodeGenFunction &CGF,
144 const ObjCAtTryStmt &S,
145 llvm::FunctionCallee beginCatchFn,
146 llvm::FunctionCallee endCatchFn,
147 llvm::FunctionCallee exceptionRethrowFn) {
148 // Jump destination for falling out of catch bodies.
149 CodeGenFunction::JumpDest Cont;
150 if (S.getNumCatchStmts())
151 Cont = CGF.getJumpDestInCurrentScope("eh.cont");
152
153 bool useFunclets = EHPersonality::get(CGF).usesFuncletPads();
154
155 CodeGenFunction::FinallyInfo FinallyInfo;
156 if (!useFunclets)
157 if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
158 FinallyInfo.enter(CGF, Finally->getFinallyBody(),
159 beginCatchFn, endCatchFn, exceptionRethrowFn);
160
161 SmallVector<CatchHandler, 8> Handlers;
162
163
164 // Enter the catch, if there is one.
165 if (S.getNumCatchStmts()) {
166 for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; ++I) {
167 const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
168 const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
169
170 Handlers.push_back(CatchHandler());
171 CatchHandler &Handler = Handlers.back();
172 Handler.Variable = CatchDecl;
173 Handler.Body = CatchStmt->getCatchBody();
174 Handler.Block = CGF.createBasicBlock("catch");
175 Handler.Flags = 0;
176
177 // @catch(...) always matches.
178 if (!CatchDecl) {
179 auto catchAll = getCatchAllTypeInfo();
180 Handler.TypeInfo = catchAll.RTTI;
181 Handler.Flags = catchAll.Flags;
182 // Don't consider any other catches.
183 break;
184 }
185
186 Handler.TypeInfo = GetEHType(CatchDecl->getType());
187 }
188
189 EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
190 for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
191 Catch->setHandler(I, { Handlers[I].TypeInfo, Handlers[I].Flags }, Handlers[I].Block);
192 }
193
194 if (useFunclets)
195 if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt()) {
196 CodeGenFunction HelperCGF(CGM, /*suppressNewContext=*/true);
197 if (!CGF.CurSEHParent)
198 CGF.CurSEHParent = cast<NamedDecl>(CGF.CurFuncDecl);
199 // Outline the finally block.
200 const Stmt *FinallyBlock = Finally->getFinallyBody();
201 HelperCGF.startOutlinedSEHHelper(CGF, /*isFilter*/false, FinallyBlock);
202
203 // Emit the original filter expression, convert to i32, and return.
204 HelperCGF.EmitStmt(FinallyBlock);
205
206 HelperCGF.FinishFunction(FinallyBlock->getEndLoc());
207
208 llvm::Function *FinallyFunc = HelperCGF.CurFn;
209
210
211 // Push a cleanup for __finally blocks.
212 CGF.pushSEHCleanup(NormalAndEHCleanup, FinallyFunc);
213 }
214
215
216 // Emit the try body.
217 CGF.EmitStmt(S.getTryBody());
218
219 // Leave the try.
220 if (S.getNumCatchStmts())
221 CGF.popCatchScope();
222
223 // Remember where we were.
224 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
225
226 // Emit the handlers.
227 for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
228 CatchHandler &Handler = Handlers[I];
229
230 CGF.EmitBlock(Handler.Block);
231 llvm::CatchPadInst *CPI = nullptr;
232 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(CGF.CurrentFuncletPad);
233 if (useFunclets)
234 if ((CPI = dyn_cast_or_null<llvm::CatchPadInst>(Handler.Block->getFirstNonPHI()))) {
235 CGF.CurrentFuncletPad = CPI;
236 CPI->setOperand(2, CGF.getExceptionSlot().getPointer());
237 }
238 llvm::Value *RawExn = CGF.getExceptionFromSlot();
239
240 // Enter the catch.
241 llvm::Value *Exn = RawExn;
242 if (beginCatchFn)
243 Exn = CGF.EmitNounwindRuntimeCall(beginCatchFn, RawExn, "exn.adjusted");
244
245 CodeGenFunction::LexicalScope cleanups(CGF, Handler.Body->getSourceRange());
246
247 if (endCatchFn) {
248 // Add a cleanup to leave the catch.
249 bool EndCatchMightThrow = (Handler.Variable == nullptr);
250
251 CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
252 EndCatchMightThrow,
253 endCatchFn);
254 }
255
256 // Bind the catch parameter if it exists.
257 if (const VarDecl *CatchParam = Handler.Variable) {
258 llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
259 llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
260
261 CGF.EmitAutoVarDecl(*CatchParam);
262 EmitInitOfCatchParam(CGF, CastExn, CatchParam);
263 }
264 if (CPI)
265 CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
266
267 CGF.ObjCEHValueStack.push_back(Exn);
268 CGF.EmitStmt(Handler.Body);
269 CGF.ObjCEHValueStack.pop_back();
270
271 // Leave any cleanups associated with the catch.
272 cleanups.ForceCleanup();
273
274 CGF.EmitBranchThroughCleanup(Cont);
275 }
276
277 // Go back to the try-statement fallthrough.
278 CGF.Builder.restoreIP(SavedIP);
279
280 // Pop out of the finally.
281 if (!useFunclets && S.getFinallyStmt())
282 FinallyInfo.exit(CGF);
283
284 if (Cont.isValid())
285 CGF.EmitBlock(Cont.getBlock());
286}
287
288void CGObjCRuntime::EmitInitOfCatchParam(CodeGenFunction &CGF,
289 llvm::Value *exn,
290 const VarDecl *paramDecl) {
291
292 Address paramAddr = CGF.GetAddrOfLocalVar(paramDecl);
293
294 switch (paramDecl->getType().getQualifiers().getObjCLifetime()) {
295 case Qualifiers::OCL_Strong:
296 exn = CGF.EmitARCRetainNonBlock(exn);
297 LLVM_FALLTHROUGH;
298
299 case Qualifiers::OCL_None:
300 case Qualifiers::OCL_ExplicitNone:
301 case Qualifiers::OCL_Autoreleasing:
302 CGF.Builder.CreateStore(exn, paramAddr);
303 return;
304
305 case Qualifiers::OCL_Weak:
306 CGF.EmitARCInitWeak(paramAddr, exn);
307 return;
308 }
309 llvm_unreachable("invalid ownership qualifier");
310}
311
312namespace {
313 struct CallSyncExit final : EHScopeStack::Cleanup {
314 llvm::FunctionCallee SyncExitFn;
315 llvm::Value *SyncArg;
316 CallSyncExit(llvm::FunctionCallee SyncExitFn, llvm::Value *SyncArg)
317 : SyncExitFn(SyncExitFn), SyncArg(SyncArg) {}
318
319 void Emit(CodeGenFunction &CGF, Flags flags) override {
320 CGF.EmitNounwindRuntimeCall(SyncExitFn, SyncArg);
321 }
322 };
323}
324
325void CGObjCRuntime::EmitAtSynchronizedStmt(CodeGenFunction &CGF,
326 const ObjCAtSynchronizedStmt &S,
327 llvm::FunctionCallee syncEnterFn,
328 llvm::FunctionCallee syncExitFn) {
329 CodeGenFunction::RunCleanupsScope cleanups(CGF);
330
331 // Evaluate the lock operand. This is guaranteed to dominate the
332 // ARC release and lock-release cleanups.
333 const Expr *lockExpr = S.getSynchExpr();
334 llvm::Value *lock;
335 if (CGF.getLangOpts().ObjCAutoRefCount) {
336 lock = CGF.EmitARCRetainScalarExpr(lockExpr);
337 lock = CGF.EmitObjCConsumeObject(lockExpr->getType(), lock);
338 } else {
339 lock = CGF.EmitScalarExpr(lockExpr);
340 }
341 lock = CGF.Builder.CreateBitCast(lock, CGF.VoidPtrTy);
342
343 // Acquire the lock.
344 CGF.Builder.CreateCall(syncEnterFn, lock)->setDoesNotThrow();
345
346 // Register an all-paths cleanup to release the lock.
347 CGF.EHStack.pushCleanup<CallSyncExit>(NormalAndEHCleanup, syncExitFn, lock);
348
349 // Emit the body of the statement.
350 CGF.EmitStmt(S.getSynchBody());
351}
352
353/// Compute the pointer-to-function type to which a message send
354/// should be casted in order to correctly call the given method
355/// with the given arguments.
356///
357/// \param method - may be null
358/// \param resultType - the result type to use if there's no method
359/// \param callArgs - the actual arguments, including implicit ones
360CGObjCRuntime::MessageSendInfo
361CGObjCRuntime::getMessageSendInfo(const ObjCMethodDecl *method,
362 QualType resultType,
363 CallArgList &callArgs) {
364 // If there's a method, use information from that.
365 if (method) {
366 const CGFunctionInfo &signature =
367 CGM.getTypes().arrangeObjCMessageSendSignature(method, callArgs[0].Ty);
368
369 llvm::PointerType *signatureType =
370 CGM.getTypes().GetFunctionType(signature)->getPointerTo();
371
372 const CGFunctionInfo &signatureForCall =
373 CGM.getTypes().arrangeCall(signature, callArgs);
374
375 return MessageSendInfo(signatureForCall, signatureType);
376 }
377
378 // There's no method; just use a default CC.
379 const CGFunctionInfo &argsInfo =
380 CGM.getTypes().arrangeUnprototypedObjCMessageSend(resultType, callArgs);
381
382 // Derive the signature to call from that.
383 llvm::PointerType *signatureType =
384 CGM.getTypes().GetFunctionType(argsInfo)->getPointerTo();
385 return MessageSendInfo(argsInfo, signatureType);
386}
387
388llvm::Constant *
389clang::CodeGen::emitObjCProtocolObject(CodeGenModule &CGM,
390 const ObjCProtocolDecl *protocol) {
391 return CGM.getObjCRuntime().GetOrEmitProtocol(protocol);
392}
393
394std::string CGObjCRuntime::getSymbolNameForMethod(const ObjCMethodDecl *OMD,
395 bool includeCategoryName) {
396 std::string buffer;
397 llvm::raw_string_ostream out(buffer);
398 CGM.getCXXABI().getMangleContext().mangleObjCMethodName(OMD, out,
399 /*includePrefixByte=*/true,
400 includeCategoryName);
401 return buffer;
402}
403