CodeGenFunction.cpp revision 85e74acfcfb0c835a2e6c1adab314e997917039a
1//===--- CodeGenFunction.cpp - Emit LLVM Code from ASTs for a Function ----===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This coordinates the per-function state used while generating code. 11// 12//===----------------------------------------------------------------------===// 13 14#include "CodeGenFunction.h" 15#include "CodeGenModule.h" 16#include "CGDebugInfo.h" 17#include "clang/Basic/TargetInfo.h" 18#include "clang/AST/APValue.h" 19#include "clang/AST/ASTContext.h" 20#include "clang/AST/Decl.h" 21#include "clang/AST/DeclCXX.h" 22#include "llvm/Target/TargetData.h" 23using namespace clang; 24using namespace CodeGen; 25 26CodeGenFunction::CodeGenFunction(CodeGenModule &cgm) 27 : BlockFunction(cgm, *this, Builder), CGM(cgm), 28 Target(CGM.getContext().Target), 29 Builder(cgm.getModule().getContext()), 30 DebugInfo(0), IndirectGotoSwitch(0), 31 SwitchInsn(0), CaseRangeBlock(0), InvokeDest(0), 32 CXXThisDecl(0) { 33 LLVMIntTy = ConvertType(getContext().IntTy); 34 LLVMPointerWidth = Target.getPointerWidth(0); 35} 36 37ASTContext &CodeGenFunction::getContext() const { 38 return CGM.getContext(); 39} 40 41 42llvm::BasicBlock *CodeGenFunction::getBasicBlockForLabel(const LabelStmt *S) { 43 llvm::BasicBlock *&BB = LabelMap[S]; 44 if (BB) return BB; 45 46 // Create, but don't insert, the new block. 47 return BB = createBasicBlock(S->getName()); 48} 49 50llvm::Value *CodeGenFunction::GetAddrOfLocalVar(const VarDecl *VD) { 51 llvm::Value *Res = LocalDeclMap[VD]; 52 assert(Res && "Invalid argument to GetAddrOfLocalVar(), no decl!"); 53 return Res; 54} 55 56llvm::Constant * 57CodeGenFunction::GetAddrOfStaticLocalVar(const VarDecl *BVD) { 58 return cast<llvm::Constant>(GetAddrOfLocalVar(BVD)); 59} 60 61const llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) { 62 return CGM.getTypes().ConvertTypeForMem(T); 63} 64 65const llvm::Type *CodeGenFunction::ConvertType(QualType T) { 66 return CGM.getTypes().ConvertType(T); 67} 68 69bool CodeGenFunction::hasAggregateLLVMType(QualType T) { 70 return T->isRecordType() || T->isArrayType() || T->isAnyComplexType() || 71 T->isMemberFunctionPointerType(); 72} 73 74void CodeGenFunction::EmitReturnBlock() { 75 // For cleanliness, we try to avoid emitting the return block for 76 // simple cases. 77 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 78 79 if (CurBB) { 80 assert(!CurBB->getTerminator() && "Unexpected terminated block."); 81 82 // We have a valid insert point, reuse it if it is empty or there are no 83 // explicit jumps to the return block. 84 if (CurBB->empty() || ReturnBlock->use_empty()) { 85 ReturnBlock->replaceAllUsesWith(CurBB); 86 delete ReturnBlock; 87 } else 88 EmitBlock(ReturnBlock); 89 return; 90 } 91 92 // Otherwise, if the return block is the target of a single direct 93 // branch then we can just put the code in that block instead. This 94 // cleans up functions which started with a unified return block. 95 if (ReturnBlock->hasOneUse()) { 96 llvm::BranchInst *BI = 97 dyn_cast<llvm::BranchInst>(*ReturnBlock->use_begin()); 98 if (BI && BI->isUnconditional() && BI->getSuccessor(0) == ReturnBlock) { 99 // Reset insertion point and delete the branch. 100 Builder.SetInsertPoint(BI->getParent()); 101 BI->eraseFromParent(); 102 delete ReturnBlock; 103 return; 104 } 105 } 106 107 // FIXME: We are at an unreachable point, there is no reason to emit the block 108 // unless it has uses. However, we still need a place to put the debug 109 // region.end for now. 110 111 EmitBlock(ReturnBlock); 112} 113 114void CodeGenFunction::FinishFunction(SourceLocation EndLoc) { 115 assert(BreakContinueStack.empty() && 116 "mismatched push/pop in break/continue stack!"); 117 assert(BlockScopes.empty() && 118 "did not remove all blocks from block scope map!"); 119 assert(CleanupEntries.empty() && 120 "mismatched push/pop in cleanup stack!"); 121 122 // Emit function epilog (to return). 123 EmitReturnBlock(); 124 125 // Emit debug descriptor for function end. 126 if (CGDebugInfo *DI = getDebugInfo()) { 127 DI->setLocation(EndLoc); 128 DI->EmitRegionEnd(CurFn, Builder); 129 } 130 131 EmitFunctionEpilog(*CurFnInfo, ReturnValue); 132 133 // Remove the AllocaInsertPt instruction, which is just a convenience for us. 134 llvm::Instruction *Ptr = AllocaInsertPt; 135 AllocaInsertPt = 0; 136 Ptr->eraseFromParent(); 137} 138 139void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy, 140 llvm::Function *Fn, 141 const FunctionArgList &Args, 142 SourceLocation StartLoc) { 143 const Decl *D = GD.getDecl(); 144 145 DidCallStackSave = false; 146 CurCodeDecl = CurFuncDecl = D; 147 FnRetTy = RetTy; 148 CurFn = Fn; 149 assert(CurFn->isDeclaration() && "Function already has body?"); 150 151 llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn); 152 153 // Create a marker to make it easy to insert allocas into the entryblock 154 // later. Don't create this with the builder, because we don't want it 155 // folded. 156 llvm::Value *Undef = llvm::UndefValue::get(llvm::Type::getInt32Ty(VMContext)); 157 AllocaInsertPt = new llvm::BitCastInst(Undef, 158 llvm::Type::getInt32Ty(VMContext), "", 159 EntryBB); 160 if (Builder.isNamePreserving()) 161 AllocaInsertPt->setName("allocapt"); 162 163 ReturnBlock = createBasicBlock("return"); 164 ReturnValue = 0; 165 if (!RetTy->isVoidType()) 166 ReturnValue = CreateTempAlloca(ConvertType(RetTy), "retval"); 167 168 Builder.SetInsertPoint(EntryBB); 169 170 QualType FnType = getContext().getFunctionType(RetTy, 0, 0, false, 0); 171 172 // Emit subprogram debug descriptor. 173 // FIXME: The cast here is a huge hack. 174 if (CGDebugInfo *DI = getDebugInfo()) { 175 DI->setLocation(StartLoc); 176 if (isa<FunctionDecl>(D)) { 177 DI->EmitFunctionStart(CGM.getMangledName(GD), FnType, CurFn, Builder); 178 } else { 179 // Just use LLVM function name. 180 181 // FIXME: Remove unnecessary conversion to std::string when API settles. 182 DI->EmitFunctionStart(std::string(Fn->getName()).c_str(), 183 FnType, CurFn, Builder); 184 } 185 } 186 187 // FIXME: Leaked. 188 CurFnInfo = &CGM.getTypes().getFunctionInfo(FnRetTy, Args); 189 EmitFunctionProlog(*CurFnInfo, CurFn, Args); 190 191 // If any of the arguments have a variably modified type, make sure to 192 // emit the type size. 193 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); 194 i != e; ++i) { 195 QualType Ty = i->second; 196 197 if (Ty->isVariablyModifiedType()) 198 EmitVLASize(Ty); 199 } 200} 201 202void CodeGenFunction::GenerateCode(GlobalDecl GD, 203 llvm::Function *Fn) { 204 const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl()); 205 206 // Check if we should generate debug info for this function. 207 if (CGM.getDebugInfo() && !FD->hasAttr<NoDebugAttr>()) 208 DebugInfo = CGM.getDebugInfo(); 209 210 FunctionArgList Args; 211 212 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) { 213 if (MD->isInstance()) { 214 // Create the implicit 'this' decl. 215 // FIXME: I'm not entirely sure I like using a fake decl just for code 216 // generation. Maybe we can come up with a better way? 217 CXXThisDecl = ImplicitParamDecl::Create(getContext(), 0, SourceLocation(), 218 &getContext().Idents.get("this"), 219 MD->getThisType(getContext())); 220 Args.push_back(std::make_pair(CXXThisDecl, CXXThisDecl->getType())); 221 } 222 } 223 224 if (FD->getNumParams()) { 225 const FunctionProtoType* FProto = FD->getType()->getAs<FunctionProtoType>(); 226 assert(FProto && "Function def must have prototype!"); 227 228 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) 229 Args.push_back(std::make_pair(FD->getParamDecl(i), 230 FProto->getArgType(i))); 231 } 232 233 // FIXME: Support CXXTryStmt here, too. 234 if (const CompoundStmt *S = FD->getCompoundBody()) { 235 StartFunction(GD, FD->getResultType(), Fn, Args, S->getLBracLoc()); 236 const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(FD); 237 llvm::BasicBlock *DtorEpilogue = 0; 238 if (DD) { 239 DtorEpilogue = createBasicBlock("dtor.epilogue"); 240 241 PushCleanupBlock(DtorEpilogue); 242 } 243 244 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) 245 EmitCtorPrologue(CD, GD.getCtorType()); 246 EmitStmt(S); 247 248 if (DD) { 249 CleanupBlockInfo Info = PopCleanupBlock(); 250 251 assert(Info.CleanupBlock == DtorEpilogue && "Block mismatch!"); 252 EmitBlock(DtorEpilogue); 253 EmitDtorEpilogue(DD, GD.getDtorType()); 254 255 if (Info.SwitchBlock) 256 EmitBlock(Info.SwitchBlock); 257 if (Info.EndBlock) 258 EmitBlock(Info.EndBlock); 259 } 260 FinishFunction(S->getRBracLoc()); 261 } else if (FD->isImplicit()) { 262 const CXXRecordDecl *ClassDecl = 263 cast<CXXRecordDecl>(FD->getDeclContext()); 264 (void) ClassDecl; 265 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) { 266 // FIXME: For C++0x, we want to look for implicit *definitions* of 267 // these special member functions, rather than implicit *declarations*. 268 if (CD->isCopyConstructor(getContext())) { 269 assert(!ClassDecl->hasUserDeclaredCopyConstructor() && 270 "Cannot synthesize a non-implicit copy constructor"); 271 SynthesizeCXXCopyConstructor(CD, GD.getCtorType(), Fn, Args); 272 } else if (CD->isDefaultConstructor()) { 273 assert(!ClassDecl->hasUserDeclaredConstructor() && 274 "Cannot synthesize a non-implicit default constructor."); 275 SynthesizeDefaultConstructor(CD, GD.getCtorType(), Fn, Args); 276 } else { 277 assert(false && "Implicit constructor cannot be synthesized"); 278 } 279 } else if (const CXXDestructorDecl *CD = dyn_cast<CXXDestructorDecl>(FD)) { 280 assert(!ClassDecl->hasUserDeclaredDestructor() && 281 "Cannot synthesize a non-implicit destructor"); 282 SynthesizeDefaultDestructor(CD, GD.getDtorType(), Fn, Args); 283 } else if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) { 284 assert(MD->isCopyAssignment() && 285 !ClassDecl->hasUserDeclaredCopyAssignment() && 286 "Cannot synthesize a method that is not an implicit-defined " 287 "copy constructor"); 288 SynthesizeCXXCopyAssignment(MD, Fn, Args); 289 } else { 290 assert(false && "Cannot synthesize unknown implicit function"); 291 } 292 } 293 294 // Destroy the 'this' declaration. 295 if (CXXThisDecl) 296 CXXThisDecl->Destroy(getContext()); 297} 298 299/// ContainsLabel - Return true if the statement contains a label in it. If 300/// this statement is not executed normally, it not containing a label means 301/// that we can just remove the code. 302bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { 303 // Null statement, not a label! 304 if (S == 0) return false; 305 306 // If this is a label, we have to emit the code, consider something like: 307 // if (0) { ... foo: bar(); } goto foo; 308 if (isa<LabelStmt>(S)) 309 return true; 310 311 // If this is a case/default statement, and we haven't seen a switch, we have 312 // to emit the code. 313 if (isa<SwitchCase>(S) && !IgnoreCaseStmts) 314 return true; 315 316 // If this is a switch statement, we want to ignore cases below it. 317 if (isa<SwitchStmt>(S)) 318 IgnoreCaseStmts = true; 319 320 // Scan subexpressions for verboten labels. 321 for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end(); 322 I != E; ++I) 323 if (ContainsLabel(*I, IgnoreCaseStmts)) 324 return true; 325 326 return false; 327} 328 329 330/// ConstantFoldsToSimpleInteger - If the sepcified expression does not fold to 331/// a constant, or if it does but contains a label, return 0. If it constant 332/// folds to 'true' and does not contain a label, return 1, if it constant folds 333/// to 'false' and does not contain a label, return -1. 334int CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond) { 335 // FIXME: Rename and handle conversion of other evaluatable things 336 // to bool. 337 Expr::EvalResult Result; 338 if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() || 339 Result.HasSideEffects) 340 return 0; // Not foldable, not integer or not fully evaluatable. 341 342 if (CodeGenFunction::ContainsLabel(Cond)) 343 return 0; // Contains a label. 344 345 return Result.Val.getInt().getBoolValue() ? 1 : -1; 346} 347 348 349/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if 350/// statement) to the specified blocks. Based on the condition, this might try 351/// to simplify the codegen of the conditional based on the branch. 352/// 353void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, 354 llvm::BasicBlock *TrueBlock, 355 llvm::BasicBlock *FalseBlock) { 356 if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) 357 return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock); 358 359 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { 360 // Handle X && Y in a condition. 361 if (CondBOp->getOpcode() == BinaryOperator::LAnd) { 362 // If we have "1 && X", simplify the code. "0 && X" would have constant 363 // folded if the case was simple enough. 364 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == 1) { 365 // br(1 && X) -> br(X). 366 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 367 } 368 369 // If we have "X && 1", simplify the code to use an uncond branch. 370 // "X && 0" would have been constant folded to 0. 371 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == 1) { 372 // br(X && 1) -> br(X). 373 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 374 } 375 376 // Emit the LHS as a conditional. If the LHS conditional is false, we 377 // want to jump to the FalseBlock. 378 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); 379 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); 380 EmitBlock(LHSTrue); 381 382 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 383 return; 384 } else if (CondBOp->getOpcode() == BinaryOperator::LOr) { 385 // If we have "0 || X", simplify the code. "1 || X" would have constant 386 // folded if the case was simple enough. 387 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == -1) { 388 // br(0 || X) -> br(X). 389 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 390 } 391 392 // If we have "X || 0", simplify the code to use an uncond branch. 393 // "X || 1" would have been constant folded to 1. 394 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == -1) { 395 // br(X || 0) -> br(X). 396 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 397 } 398 399 // Emit the LHS as a conditional. If the LHS conditional is true, we 400 // want to jump to the TrueBlock. 401 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); 402 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); 403 EmitBlock(LHSFalse); 404 405 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 406 return; 407 } 408 } 409 410 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { 411 // br(!x, t, f) -> br(x, f, t) 412 if (CondUOp->getOpcode() == UnaryOperator::LNot) 413 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); 414 } 415 416 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) { 417 // Handle ?: operator. 418 419 // Just ignore GNU ?: extension. 420 if (CondOp->getLHS()) { 421 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) 422 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); 423 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); 424 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); 425 EmitBlock(LHSBlock); 426 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); 427 EmitBlock(RHSBlock); 428 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); 429 return; 430 } 431 } 432 433 // Emit the code with the fully general case. 434 llvm::Value *CondV = EvaluateExprAsBool(Cond); 435 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); 436} 437 438/// ErrorUnsupported - Print out an error that codegen doesn't support the 439/// specified stmt yet. 440void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, 441 bool OmitOnError) { 442 CGM.ErrorUnsupported(S, Type, OmitOnError); 443} 444 445void CodeGenFunction::EmitMemSetToZero(llvm::Value *DestPtr, QualType Ty) { 446 const llvm::Type *BP = llvm::Type::getInt8PtrTy(VMContext); 447 if (DestPtr->getType() != BP) 448 DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); 449 450 // Get size and alignment info for this aggregate. 451 std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); 452 453 // Don't bother emitting a zero-byte memset. 454 if (TypeInfo.first == 0) 455 return; 456 457 // FIXME: Handle variable sized types. 458 const llvm::Type *IntPtr = llvm::IntegerType::get(VMContext, 459 LLVMPointerWidth); 460 461 Builder.CreateCall4(CGM.getMemSetFn(), DestPtr, 462 llvm::Constant::getNullValue(llvm::Type::getInt8Ty(VMContext)), 463 // TypeInfo.first describes size in bits. 464 llvm::ConstantInt::get(IntPtr, TypeInfo.first/8), 465 llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 466 TypeInfo.second/8)); 467} 468 469unsigned CodeGenFunction::GetIDForAddrOfLabel(const LabelStmt *L) { 470 // Use LabelIDs.size()+1 as the new ID if one hasn't been assigned. 471 unsigned &Entry = LabelIDs[L]; 472 if (Entry) return Entry; 473 474 Entry = LabelIDs.size(); 475 476 // If this is the first "address taken" of a label and the indirect goto has 477 // already been seen, add this to it. 478 if (IndirectGotoSwitch) { 479 // If this is the first address-taken label, set it as the default dest. 480 if (Entry == 1) 481 IndirectGotoSwitch->setSuccessor(0, getBasicBlockForLabel(L)); 482 else { 483 // Otherwise add it to the switch as a new dest. 484 const llvm::IntegerType *Int32Ty = llvm::Type::getInt32Ty(VMContext); 485 IndirectGotoSwitch->addCase(llvm::ConstantInt::get(Int32Ty, Entry), 486 getBasicBlockForLabel(L)); 487 } 488 } 489 490 return Entry; 491} 492 493llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() { 494 // If we already made the switch stmt for indirect goto, return its block. 495 if (IndirectGotoSwitch) return IndirectGotoSwitch->getParent(); 496 497 EmitBlock(createBasicBlock("indirectgoto")); 498 499 const llvm::IntegerType *Int32Ty = llvm::Type::getInt32Ty(VMContext); 500 501 // Create the PHI node that indirect gotos will add entries to. 502 llvm::Value *DestVal = Builder.CreatePHI(Int32Ty, "indirect.goto.dest"); 503 504 // Create the switch instruction. For now, set the insert block to this block 505 // which will be fixed as labels are added. 506 IndirectGotoSwitch = Builder.CreateSwitch(DestVal, Builder.GetInsertBlock()); 507 508 // Clear the insertion point to indicate we are in unreachable code. 509 Builder.ClearInsertionPoint(); 510 511 // If we already have labels created, add them. 512 if (!LabelIDs.empty()) { 513 // Invert LabelID's so that the order is determinstic. 514 std::vector<const LabelStmt*> AddrTakenLabelsByID; 515 AddrTakenLabelsByID.resize(LabelIDs.size()); 516 517 for (std::map<const LabelStmt*,unsigned>::iterator 518 LI = LabelIDs.begin(), LE = LabelIDs.end(); LI != LE; ++LI) { 519 assert(LI->second-1 < AddrTakenLabelsByID.size() && 520 "Numbering inconsistent"); 521 AddrTakenLabelsByID[LI->second-1] = LI->first; 522 } 523 524 // Set the default entry as the first block. 525 IndirectGotoSwitch->setSuccessor(0, 526 getBasicBlockForLabel(AddrTakenLabelsByID[0])); 527 528 // FIXME: The iteration order of this is nondeterminstic! 529 for (unsigned i = 1, e = AddrTakenLabelsByID.size(); i != e; ++i) 530 IndirectGotoSwitch->addCase(llvm::ConstantInt::get(Int32Ty, i+1), 531 getBasicBlockForLabel(AddrTakenLabelsByID[i])); 532 } else { 533 // Otherwise, create a dead block and set it as the default dest. This will 534 // be removed by the optimizers after the indirect goto is set up. 535 llvm::BasicBlock *Dummy = createBasicBlock("indgoto.dummy"); 536 EmitBlock(Dummy); 537 IndirectGotoSwitch->setSuccessor(0, Dummy); 538 Builder.CreateUnreachable(); 539 Builder.ClearInsertionPoint(); 540 } 541 542 return IndirectGotoSwitch->getParent(); 543} 544 545llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) { 546 llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; 547 548 assert(SizeEntry && "Did not emit size for type"); 549 return SizeEntry; 550} 551 552llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) { 553 assert(Ty->isVariablyModifiedType() && 554 "Must pass variably modified type to EmitVLASizes!"); 555 556 EnsureInsertPoint(); 557 558 if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) { 559 llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; 560 561 if (!SizeEntry) { 562 const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); 563 564 // Get the element size; 565 QualType ElemTy = VAT->getElementType(); 566 llvm::Value *ElemSize; 567 if (ElemTy->isVariableArrayType()) 568 ElemSize = EmitVLASize(ElemTy); 569 else 570 ElemSize = llvm::ConstantInt::get(SizeTy, 571 getContext().getTypeSize(ElemTy) / 8); 572 573 llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr()); 574 NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp"); 575 576 SizeEntry = Builder.CreateMul(ElemSize, NumElements); 577 } 578 579 return SizeEntry; 580 } 581 582 if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) { 583 EmitVLASize(AT->getElementType()); 584 return 0; 585 } 586 587 const PointerType *PT = Ty->getAs<PointerType>(); 588 assert(PT && "unknown VM type!"); 589 EmitVLASize(PT->getPointeeType()); 590 return 0; 591} 592 593llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { 594 if (CGM.getContext().getBuiltinVaListType()->isArrayType()) { 595 return EmitScalarExpr(E); 596 } 597 return EmitLValue(E).getAddress(); 598} 599 600void CodeGenFunction::PushCleanupBlock(llvm::BasicBlock *CleanupBlock) { 601 CleanupEntries.push_back(CleanupEntry(CleanupBlock)); 602} 603 604void CodeGenFunction::EmitCleanupBlocks(size_t OldCleanupStackSize) { 605 assert(CleanupEntries.size() >= OldCleanupStackSize && 606 "Cleanup stack mismatch!"); 607 608 while (CleanupEntries.size() > OldCleanupStackSize) 609 EmitCleanupBlock(); 610} 611 612CodeGenFunction::CleanupBlockInfo CodeGenFunction::PopCleanupBlock() { 613 CleanupEntry &CE = CleanupEntries.back(); 614 615 llvm::BasicBlock *CleanupBlock = CE.CleanupBlock; 616 617 std::vector<llvm::BasicBlock *> Blocks; 618 std::swap(Blocks, CE.Blocks); 619 620 std::vector<llvm::BranchInst *> BranchFixups; 621 std::swap(BranchFixups, CE.BranchFixups); 622 623 CleanupEntries.pop_back(); 624 625 // Check if any branch fixups pointed to the scope we just popped. If so, 626 // we can remove them. 627 for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) { 628 llvm::BasicBlock *Dest = BranchFixups[i]->getSuccessor(0); 629 BlockScopeMap::iterator I = BlockScopes.find(Dest); 630 631 if (I == BlockScopes.end()) 632 continue; 633 634 assert(I->second <= CleanupEntries.size() && "Invalid branch fixup!"); 635 636 if (I->second == CleanupEntries.size()) { 637 // We don't need to do this branch fixup. 638 BranchFixups[i] = BranchFixups.back(); 639 BranchFixups.pop_back(); 640 i--; 641 e--; 642 continue; 643 } 644 } 645 646 llvm::BasicBlock *SwitchBlock = 0; 647 llvm::BasicBlock *EndBlock = 0; 648 if (!BranchFixups.empty()) { 649 SwitchBlock = createBasicBlock("cleanup.switch"); 650 EndBlock = createBasicBlock("cleanup.end"); 651 652 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 653 654 Builder.SetInsertPoint(SwitchBlock); 655 656 llvm::Value *DestCodePtr = CreateTempAlloca(llvm::Type::getInt32Ty(VMContext), 657 "cleanup.dst"); 658 llvm::Value *DestCode = Builder.CreateLoad(DestCodePtr, "tmp"); 659 660 // Create a switch instruction to determine where to jump next. 661 llvm::SwitchInst *SI = Builder.CreateSwitch(DestCode, EndBlock, 662 BranchFixups.size()); 663 664 // Restore the current basic block (if any) 665 if (CurBB) { 666 Builder.SetInsertPoint(CurBB); 667 668 // If we had a current basic block, we also need to emit an instruction 669 // to initialize the cleanup destination. 670 Builder.CreateStore(llvm::Constant::getNullValue(llvm::Type::getInt32Ty(VMContext)), 671 DestCodePtr); 672 } else 673 Builder.ClearInsertionPoint(); 674 675 for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) { 676 llvm::BranchInst *BI = BranchFixups[i]; 677 llvm::BasicBlock *Dest = BI->getSuccessor(0); 678 679 // Fixup the branch instruction to point to the cleanup block. 680 BI->setSuccessor(0, CleanupBlock); 681 682 if (CleanupEntries.empty()) { 683 llvm::ConstantInt *ID; 684 685 // Check if we already have a destination for this block. 686 if (Dest == SI->getDefaultDest()) 687 ID = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 0); 688 else { 689 ID = SI->findCaseDest(Dest); 690 if (!ID) { 691 // No code found, get a new unique one by using the number of 692 // switch successors. 693 ID = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 694 SI->getNumSuccessors()); 695 SI->addCase(ID, Dest); 696 } 697 } 698 699 // Store the jump destination before the branch instruction. 700 new llvm::StoreInst(ID, DestCodePtr, BI); 701 } else { 702 // We need to jump through another cleanup block. Create a pad block 703 // with a branch instruction that jumps to the final destination and 704 // add it as a branch fixup to the current cleanup scope. 705 706 // Create the pad block. 707 llvm::BasicBlock *CleanupPad = createBasicBlock("cleanup.pad", CurFn); 708 709 // Create a unique case ID. 710 llvm::ConstantInt *ID = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 711 SI->getNumSuccessors()); 712 713 // Store the jump destination before the branch instruction. 714 new llvm::StoreInst(ID, DestCodePtr, BI); 715 716 // Add it as the destination. 717 SI->addCase(ID, CleanupPad); 718 719 // Create the branch to the final destination. 720 llvm::BranchInst *BI = llvm::BranchInst::Create(Dest); 721 CleanupPad->getInstList().push_back(BI); 722 723 // And add it as a branch fixup. 724 CleanupEntries.back().BranchFixups.push_back(BI); 725 } 726 } 727 } 728 729 // Remove all blocks from the block scope map. 730 for (size_t i = 0, e = Blocks.size(); i != e; ++i) { 731 assert(BlockScopes.count(Blocks[i]) && 732 "Did not find block in scope map!"); 733 734 BlockScopes.erase(Blocks[i]); 735 } 736 737 return CleanupBlockInfo(CleanupBlock, SwitchBlock, EndBlock); 738} 739 740void CodeGenFunction::EmitCleanupBlock() { 741 CleanupBlockInfo Info = PopCleanupBlock(); 742 743 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 744 if (CurBB && !CurBB->getTerminator() && 745 Info.CleanupBlock->getNumUses() == 0) { 746 CurBB->getInstList().splice(CurBB->end(), Info.CleanupBlock->getInstList()); 747 delete Info.CleanupBlock; 748 } else 749 EmitBlock(Info.CleanupBlock); 750 751 if (Info.SwitchBlock) 752 EmitBlock(Info.SwitchBlock); 753 if (Info.EndBlock) 754 EmitBlock(Info.EndBlock); 755} 756 757void CodeGenFunction::AddBranchFixup(llvm::BranchInst *BI) { 758 assert(!CleanupEntries.empty() && 759 "Trying to add branch fixup without cleanup block!"); 760 761 // FIXME: We could be more clever here and check if there's already a branch 762 // fixup for this destination and recycle it. 763 CleanupEntries.back().BranchFixups.push_back(BI); 764} 765 766void CodeGenFunction::EmitBranchThroughCleanup(llvm::BasicBlock *Dest) { 767 if (!HaveInsertPoint()) 768 return; 769 770 llvm::BranchInst* BI = Builder.CreateBr(Dest); 771 772 Builder.ClearInsertionPoint(); 773 774 // The stack is empty, no need to do any cleanup. 775 if (CleanupEntries.empty()) 776 return; 777 778 if (!Dest->getParent()) { 779 // We are trying to branch to a block that hasn't been inserted yet. 780 AddBranchFixup(BI); 781 return; 782 } 783 784 BlockScopeMap::iterator I = BlockScopes.find(Dest); 785 if (I == BlockScopes.end()) { 786 // We are trying to jump to a block that is outside of any cleanup scope. 787 AddBranchFixup(BI); 788 return; 789 } 790 791 assert(I->second < CleanupEntries.size() && 792 "Trying to branch into cleanup region"); 793 794 if (I->second == CleanupEntries.size() - 1) { 795 // We have a branch to a block in the same scope. 796 return; 797 } 798 799 AddBranchFixup(BI); 800} 801