CodeGenFunction.cpp revision 203955
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 "clang/AST/StmtCXX.h" 23#include "llvm/Target/TargetData.h" 24using namespace clang; 25using namespace CodeGen; 26 27CodeGenFunction::CodeGenFunction(CodeGenModule &cgm) 28 : BlockFunction(cgm, *this, Builder), CGM(cgm), 29 Target(CGM.getContext().Target), 30 Builder(cgm.getModule().getContext()), 31 DebugInfo(0), IndirectBranch(0), 32 SwitchInsn(0), CaseRangeBlock(0), InvokeDest(0), 33 CXXThisDecl(0), CXXVTTDecl(0), 34 ConditionalBranchLevel(0), TerminateHandler(0), TrapBB(0), 35 UniqueAggrDestructorCount(0) { 36 LLVMIntTy = ConvertType(getContext().IntTy); 37 LLVMPointerWidth = Target.getPointerWidth(0); 38 Exceptions = getContext().getLangOptions().Exceptions; 39 CatchUndefined = getContext().getLangOptions().CatchUndefined; 40} 41 42ASTContext &CodeGenFunction::getContext() const { 43 return CGM.getContext(); 44} 45 46 47llvm::BasicBlock *CodeGenFunction::getBasicBlockForLabel(const LabelStmt *S) { 48 llvm::BasicBlock *&BB = LabelMap[S]; 49 if (BB) return BB; 50 51 // Create, but don't insert, the new block. 52 return BB = createBasicBlock(S->getName()); 53} 54 55llvm::Value *CodeGenFunction::GetAddrOfLocalVar(const VarDecl *VD) { 56 llvm::Value *Res = LocalDeclMap[VD]; 57 assert(Res && "Invalid argument to GetAddrOfLocalVar(), no decl!"); 58 return Res; 59} 60 61llvm::Constant * 62CodeGenFunction::GetAddrOfStaticLocalVar(const VarDecl *BVD) { 63 return cast<llvm::Constant>(GetAddrOfLocalVar(BVD)); 64} 65 66const llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) { 67 return CGM.getTypes().ConvertTypeForMem(T); 68} 69 70const llvm::Type *CodeGenFunction::ConvertType(QualType T) { 71 return CGM.getTypes().ConvertType(T); 72} 73 74bool CodeGenFunction::hasAggregateLLVMType(QualType T) { 75 return T->isRecordType() || T->isArrayType() || T->isAnyComplexType() || 76 T->isMemberFunctionPointerType(); 77} 78 79void CodeGenFunction::EmitReturnBlock() { 80 // For cleanliness, we try to avoid emitting the return block for 81 // simple cases. 82 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 83 84 if (CurBB) { 85 assert(!CurBB->getTerminator() && "Unexpected terminated block."); 86 87 // We have a valid insert point, reuse it if it is empty or there are no 88 // explicit jumps to the return block. 89 if (CurBB->empty() || ReturnBlock->use_empty()) { 90 ReturnBlock->replaceAllUsesWith(CurBB); 91 delete ReturnBlock; 92 } else 93 EmitBlock(ReturnBlock); 94 return; 95 } 96 97 // Otherwise, if the return block is the target of a single direct 98 // branch then we can just put the code in that block instead. This 99 // cleans up functions which started with a unified return block. 100 if (ReturnBlock->hasOneUse()) { 101 llvm::BranchInst *BI = 102 dyn_cast<llvm::BranchInst>(*ReturnBlock->use_begin()); 103 if (BI && BI->isUnconditional() && BI->getSuccessor(0) == ReturnBlock) { 104 // Reset insertion point and delete the branch. 105 Builder.SetInsertPoint(BI->getParent()); 106 BI->eraseFromParent(); 107 delete ReturnBlock; 108 return; 109 } 110 } 111 112 // FIXME: We are at an unreachable point, there is no reason to emit the block 113 // unless it has uses. However, we still need a place to put the debug 114 // region.end for now. 115 116 EmitBlock(ReturnBlock); 117} 118 119void CodeGenFunction::FinishFunction(SourceLocation EndLoc) { 120 assert(BreakContinueStack.empty() && 121 "mismatched push/pop in break/continue stack!"); 122 assert(BlockScopes.empty() && 123 "did not remove all blocks from block scope map!"); 124 assert(CleanupEntries.empty() && 125 "mismatched push/pop in cleanup stack!"); 126 127 // Emit function epilog (to return). 128 EmitReturnBlock(); 129 130 // Emit debug descriptor for function end. 131 if (CGDebugInfo *DI = getDebugInfo()) { 132 DI->setLocation(EndLoc); 133 DI->EmitRegionEnd(CurFn, Builder); 134 } 135 136 EmitFunctionEpilog(*CurFnInfo, ReturnValue); 137 EmitEndEHSpec(CurCodeDecl); 138 139 // If someone did an indirect goto, emit the indirect goto block at the end of 140 // the function. 141 if (IndirectBranch) { 142 EmitBlock(IndirectBranch->getParent()); 143 Builder.ClearInsertionPoint(); 144 } 145 146 // Remove the AllocaInsertPt instruction, which is just a convenience for us. 147 llvm::Instruction *Ptr = AllocaInsertPt; 148 AllocaInsertPt = 0; 149 Ptr->eraseFromParent(); 150 151 // If someone took the address of a label but never did an indirect goto, we 152 // made a zero entry PHI node, which is illegal, zap it now. 153 if (IndirectBranch) { 154 llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress()); 155 if (PN->getNumIncomingValues() == 0) { 156 PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType())); 157 PN->eraseFromParent(); 158 } 159 } 160} 161 162void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy, 163 llvm::Function *Fn, 164 const FunctionArgList &Args, 165 SourceLocation StartLoc) { 166 const Decl *D = GD.getDecl(); 167 168 DidCallStackSave = false; 169 CurCodeDecl = CurFuncDecl = D; 170 FnRetTy = RetTy; 171 CurFn = Fn; 172 assert(CurFn->isDeclaration() && "Function already has body?"); 173 174 // Pass inline keyword to optimizer if it appears explicitly on any 175 // declaration. 176 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) 177 for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(), 178 RE = FD->redecls_end(); RI != RE; ++RI) 179 if (RI->isInlineSpecified()) { 180 Fn->addFnAttr(llvm::Attribute::InlineHint); 181 break; 182 } 183 184 llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn); 185 186 // Create a marker to make it easy to insert allocas into the entryblock 187 // later. Don't create this with the builder, because we don't want it 188 // folded. 189 llvm::Value *Undef = llvm::UndefValue::get(llvm::Type::getInt32Ty(VMContext)); 190 AllocaInsertPt = new llvm::BitCastInst(Undef, 191 llvm::Type::getInt32Ty(VMContext), "", 192 EntryBB); 193 if (Builder.isNamePreserving()) 194 AllocaInsertPt->setName("allocapt"); 195 196 ReturnBlock = createBasicBlock("return"); 197 198 Builder.SetInsertPoint(EntryBB); 199 200 QualType FnType = getContext().getFunctionType(RetTy, 0, 0, false, 0); 201 202 // Emit subprogram debug descriptor. 203 if (CGDebugInfo *DI = getDebugInfo()) { 204 DI->setLocation(StartLoc); 205 DI->EmitFunctionStart(GD, FnType, CurFn, Builder); 206 } 207 208 // FIXME: Leaked. 209 // CC info is ignored, hopefully? 210 CurFnInfo = &CGM.getTypes().getFunctionInfo(FnRetTy, Args, 211 CC_Default, false); 212 213 if (RetTy->isVoidType()) { 214 // Void type; nothing to return. 215 ReturnValue = 0; 216 } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect && 217 hasAggregateLLVMType(CurFnInfo->getReturnType())) { 218 // Indirect aggregate return; emit returned value directly into sret slot. 219 // This reduces code size, and is also affects correctness in C++. 220 ReturnValue = CurFn->arg_begin(); 221 } else { 222 ReturnValue = CreateTempAlloca(ConvertType(RetTy), "retval"); 223 } 224 225 EmitStartEHSpec(CurCodeDecl); 226 EmitFunctionProlog(*CurFnInfo, CurFn, Args); 227 228 // If any of the arguments have a variably modified type, make sure to 229 // emit the type size. 230 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); 231 i != e; ++i) { 232 QualType Ty = i->second; 233 234 if (Ty->isVariablyModifiedType()) 235 EmitVLASize(Ty); 236 } 237} 238 239void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn) { 240 const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl()); 241 242 // Check if we should generate debug info for this function. 243 if (CGM.getDebugInfo() && !FD->hasAttr<NoDebugAttr>()) 244 DebugInfo = CGM.getDebugInfo(); 245 246 FunctionArgList Args; 247 248 CurGD = GD; 249 OuterTryBlock = 0; 250 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) { 251 if (MD->isInstance()) { 252 // Create the implicit 'this' decl. 253 // FIXME: I'm not entirely sure I like using a fake decl just for code 254 // generation. Maybe we can come up with a better way? 255 CXXThisDecl = ImplicitParamDecl::Create(getContext(), 0, SourceLocation(), 256 &getContext().Idents.get("this"), 257 MD->getThisType(getContext())); 258 Args.push_back(std::make_pair(CXXThisDecl, CXXThisDecl->getType())); 259 260 // Check if we need a VTT parameter as well. 261 if (CGVtableInfo::needsVTTParameter(GD)) { 262 // FIXME: The comment about using a fake decl above applies here too. 263 QualType T = getContext().getPointerType(getContext().VoidPtrTy); 264 CXXVTTDecl = 265 ImplicitParamDecl::Create(getContext(), 0, SourceLocation(), 266 &getContext().Idents.get("vtt"), T); 267 Args.push_back(std::make_pair(CXXVTTDecl, CXXVTTDecl->getType())); 268 } 269 } 270 } 271 272 if (FD->getNumParams()) { 273 const FunctionProtoType* FProto = FD->getType()->getAs<FunctionProtoType>(); 274 assert(FProto && "Function def must have prototype!"); 275 276 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) 277 Args.push_back(std::make_pair(FD->getParamDecl(i), 278 FProto->getArgType(i))); 279 } 280 281 if (const CompoundStmt *S = FD->getCompoundBody()) { 282 StartFunction(GD, FD->getResultType(), Fn, Args, S->getLBracLoc()); 283 284 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) { 285 EmitCtorPrologue(CD, GD.getCtorType()); 286 EmitStmt(S); 287 288 // If any of the member initializers are temporaries bound to references 289 // make sure to emit their destructors. 290 EmitCleanupBlocks(0); 291 292 } else if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(FD)) { 293 llvm::BasicBlock *DtorEpilogue = createBasicBlock("dtor.epilogue"); 294 PushCleanupBlock(DtorEpilogue); 295 296 InitializeVtablePtrs(DD->getParent()); 297 298 EmitStmt(S); 299 300 CleanupBlockInfo Info = PopCleanupBlock(); 301 302 assert(Info.CleanupBlock == DtorEpilogue && "Block mismatch!"); 303 EmitBlock(DtorEpilogue); 304 EmitDtorEpilogue(DD, GD.getDtorType()); 305 306 if (Info.SwitchBlock) 307 EmitBlock(Info.SwitchBlock); 308 if (Info.EndBlock) 309 EmitBlock(Info.EndBlock); 310 } else { 311 // Just a regular function, emit its body. 312 EmitStmt(S); 313 } 314 315 FinishFunction(S->getRBracLoc()); 316 } else if (FD->isImplicit()) { 317 const CXXRecordDecl *ClassDecl = 318 cast<CXXRecordDecl>(FD->getDeclContext()); 319 (void) ClassDecl; 320 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) { 321 // FIXME: For C++0x, we want to look for implicit *definitions* of 322 // these special member functions, rather than implicit *declarations*. 323 if (CD->isCopyConstructor()) { 324 assert(!ClassDecl->hasUserDeclaredCopyConstructor() && 325 "Cannot synthesize a non-implicit copy constructor"); 326 SynthesizeCXXCopyConstructor(CD, GD.getCtorType(), Fn, Args); 327 } else if (CD->isDefaultConstructor()) { 328 assert(!ClassDecl->hasUserDeclaredConstructor() && 329 "Cannot synthesize a non-implicit default constructor."); 330 SynthesizeDefaultConstructor(CD, GD.getCtorType(), Fn, Args); 331 } else { 332 assert(false && "Implicit constructor cannot be synthesized"); 333 } 334 } else if (const CXXDestructorDecl *CD = dyn_cast<CXXDestructorDecl>(FD)) { 335 assert(!ClassDecl->hasUserDeclaredDestructor() && 336 "Cannot synthesize a non-implicit destructor"); 337 SynthesizeDefaultDestructor(CD, GD.getDtorType(), Fn, Args); 338 } else if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) { 339 assert(MD->isCopyAssignment() && 340 !ClassDecl->hasUserDeclaredCopyAssignment() && 341 "Cannot synthesize a method that is not an implicit-defined " 342 "copy constructor"); 343 SynthesizeCXXCopyAssignment(MD, Fn, Args); 344 } else { 345 assert(false && "Cannot synthesize unknown implicit function"); 346 } 347 } else if (const Stmt *S = FD->getBody()) { 348 if (const CXXTryStmt *TS = dyn_cast<CXXTryStmt>(S)) { 349 OuterTryBlock = TS; 350 StartFunction(GD, FD->getResultType(), Fn, Args, TS->getTryLoc()); 351 EmitStmt(TS); 352 FinishFunction(TS->getEndLoc()); 353 } 354 } 355 356 // Destroy the 'this' declaration. 357 if (CXXThisDecl) 358 CXXThisDecl->Destroy(getContext()); 359 360 // Destroy the VTT declaration. 361 if (CXXVTTDecl) 362 CXXVTTDecl->Destroy(getContext()); 363} 364 365/// ContainsLabel - Return true if the statement contains a label in it. If 366/// this statement is not executed normally, it not containing a label means 367/// that we can just remove the code. 368bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { 369 // Null statement, not a label! 370 if (S == 0) return false; 371 372 // If this is a label, we have to emit the code, consider something like: 373 // if (0) { ... foo: bar(); } goto foo; 374 if (isa<LabelStmt>(S)) 375 return true; 376 377 // If this is a case/default statement, and we haven't seen a switch, we have 378 // to emit the code. 379 if (isa<SwitchCase>(S) && !IgnoreCaseStmts) 380 return true; 381 382 // If this is a switch statement, we want to ignore cases below it. 383 if (isa<SwitchStmt>(S)) 384 IgnoreCaseStmts = true; 385 386 // Scan subexpressions for verboten labels. 387 for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end(); 388 I != E; ++I) 389 if (ContainsLabel(*I, IgnoreCaseStmts)) 390 return true; 391 392 return false; 393} 394 395 396/// ConstantFoldsToSimpleInteger - If the sepcified expression does not fold to 397/// a constant, or if it does but contains a label, return 0. If it constant 398/// folds to 'true' and does not contain a label, return 1, if it constant folds 399/// to 'false' and does not contain a label, return -1. 400int CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond) { 401 // FIXME: Rename and handle conversion of other evaluatable things 402 // to bool. 403 Expr::EvalResult Result; 404 if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() || 405 Result.HasSideEffects) 406 return 0; // Not foldable, not integer or not fully evaluatable. 407 408 if (CodeGenFunction::ContainsLabel(Cond)) 409 return 0; // Contains a label. 410 411 return Result.Val.getInt().getBoolValue() ? 1 : -1; 412} 413 414 415/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if 416/// statement) to the specified blocks. Based on the condition, this might try 417/// to simplify the codegen of the conditional based on the branch. 418/// 419void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, 420 llvm::BasicBlock *TrueBlock, 421 llvm::BasicBlock *FalseBlock) { 422 if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) 423 return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock); 424 425 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { 426 // Handle X && Y in a condition. 427 if (CondBOp->getOpcode() == BinaryOperator::LAnd) { 428 // If we have "1 && X", simplify the code. "0 && X" would have constant 429 // folded if the case was simple enough. 430 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == 1) { 431 // br(1 && X) -> br(X). 432 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 433 } 434 435 // If we have "X && 1", simplify the code to use an uncond branch. 436 // "X && 0" would have been constant folded to 0. 437 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == 1) { 438 // br(X && 1) -> br(X). 439 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 440 } 441 442 // Emit the LHS as a conditional. If the LHS conditional is false, we 443 // want to jump to the FalseBlock. 444 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); 445 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); 446 EmitBlock(LHSTrue); 447 448 // Any temporaries created here are conditional. 449 BeginConditionalBranch(); 450 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 451 EndConditionalBranch(); 452 453 return; 454 } else if (CondBOp->getOpcode() == BinaryOperator::LOr) { 455 // If we have "0 || X", simplify the code. "1 || X" would have constant 456 // folded if the case was simple enough. 457 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == -1) { 458 // br(0 || X) -> br(X). 459 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 460 } 461 462 // If we have "X || 0", simplify the code to use an uncond branch. 463 // "X || 1" would have been constant folded to 1. 464 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == -1) { 465 // br(X || 0) -> br(X). 466 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 467 } 468 469 // Emit the LHS as a conditional. If the LHS conditional is true, we 470 // want to jump to the TrueBlock. 471 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); 472 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); 473 EmitBlock(LHSFalse); 474 475 // Any temporaries created here are conditional. 476 BeginConditionalBranch(); 477 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 478 EndConditionalBranch(); 479 480 return; 481 } 482 } 483 484 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { 485 // br(!x, t, f) -> br(x, f, t) 486 if (CondUOp->getOpcode() == UnaryOperator::LNot) 487 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); 488 } 489 490 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) { 491 // Handle ?: operator. 492 493 // Just ignore GNU ?: extension. 494 if (CondOp->getLHS()) { 495 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) 496 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); 497 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); 498 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); 499 EmitBlock(LHSBlock); 500 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); 501 EmitBlock(RHSBlock); 502 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); 503 return; 504 } 505 } 506 507 // Emit the code with the fully general case. 508 llvm::Value *CondV = EvaluateExprAsBool(Cond); 509 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); 510} 511 512/// ErrorUnsupported - Print out an error that codegen doesn't support the 513/// specified stmt yet. 514void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, 515 bool OmitOnError) { 516 CGM.ErrorUnsupported(S, Type, OmitOnError); 517} 518 519void CodeGenFunction::EmitMemSetToZero(llvm::Value *DestPtr, QualType Ty) { 520 const llvm::Type *BP = llvm::Type::getInt8PtrTy(VMContext); 521 if (DestPtr->getType() != BP) 522 DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); 523 524 // Get size and alignment info for this aggregate. 525 std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); 526 527 // Don't bother emitting a zero-byte memset. 528 if (TypeInfo.first == 0) 529 return; 530 531 // FIXME: Handle variable sized types. 532 const llvm::Type *IntPtr = llvm::IntegerType::get(VMContext, 533 LLVMPointerWidth); 534 535 Builder.CreateCall4(CGM.getMemSetFn(), DestPtr, 536 llvm::Constant::getNullValue(llvm::Type::getInt8Ty(VMContext)), 537 // TypeInfo.first describes size in bits. 538 llvm::ConstantInt::get(IntPtr, TypeInfo.first/8), 539 llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 540 TypeInfo.second/8)); 541} 542 543llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelStmt *L) { 544 // Make sure that there is a block for the indirect goto. 545 if (IndirectBranch == 0) 546 GetIndirectGotoBlock(); 547 548 llvm::BasicBlock *BB = getBasicBlockForLabel(L); 549 550 // Make sure the indirect branch includes all of the address-taken blocks. 551 IndirectBranch->addDestination(BB); 552 return llvm::BlockAddress::get(CurFn, BB); 553} 554 555llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() { 556 // If we already made the indirect branch for indirect goto, return its block. 557 if (IndirectBranch) return IndirectBranch->getParent(); 558 559 CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto")); 560 561 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext); 562 563 // Create the PHI node that indirect gotos will add entries to. 564 llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, "indirect.goto.dest"); 565 566 // Create the indirect branch instruction. 567 IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal); 568 return IndirectBranch->getParent(); 569} 570 571llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) { 572 llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; 573 574 assert(SizeEntry && "Did not emit size for type"); 575 return SizeEntry; 576} 577 578llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) { 579 assert(Ty->isVariablyModifiedType() && 580 "Must pass variably modified type to EmitVLASizes!"); 581 582 EnsureInsertPoint(); 583 584 if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) { 585 llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; 586 587 if (!SizeEntry) { 588 const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); 589 590 // Get the element size; 591 QualType ElemTy = VAT->getElementType(); 592 llvm::Value *ElemSize; 593 if (ElemTy->isVariableArrayType()) 594 ElemSize = EmitVLASize(ElemTy); 595 else 596 ElemSize = llvm::ConstantInt::get(SizeTy, 597 getContext().getTypeSizeInChars(ElemTy).getQuantity()); 598 599 llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr()); 600 NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp"); 601 602 SizeEntry = Builder.CreateMul(ElemSize, NumElements); 603 } 604 605 return SizeEntry; 606 } 607 608 if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) { 609 EmitVLASize(AT->getElementType()); 610 return 0; 611 } 612 613 const PointerType *PT = Ty->getAs<PointerType>(); 614 assert(PT && "unknown VM type!"); 615 EmitVLASize(PT->getPointeeType()); 616 return 0; 617} 618 619llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { 620 if (CGM.getContext().getBuiltinVaListType()->isArrayType()) { 621 return EmitScalarExpr(E); 622 } 623 return EmitLValue(E).getAddress(); 624} 625 626void CodeGenFunction::PushCleanupBlock(llvm::BasicBlock *CleanupEntryBlock, 627 llvm::BasicBlock *CleanupExitBlock, 628 llvm::BasicBlock *PreviousInvokeDest, 629 bool EHOnly) { 630 CleanupEntries.push_back(CleanupEntry(CleanupEntryBlock, CleanupExitBlock, 631 PreviousInvokeDest, EHOnly)); 632} 633 634void CodeGenFunction::EmitCleanupBlocks(size_t OldCleanupStackSize) { 635 assert(CleanupEntries.size() >= OldCleanupStackSize && 636 "Cleanup stack mismatch!"); 637 638 while (CleanupEntries.size() > OldCleanupStackSize) 639 EmitCleanupBlock(); 640} 641 642CodeGenFunction::CleanupBlockInfo CodeGenFunction::PopCleanupBlock() { 643 CleanupEntry &CE = CleanupEntries.back(); 644 645 llvm::BasicBlock *CleanupEntryBlock = CE.CleanupEntryBlock; 646 647 std::vector<llvm::BasicBlock *> Blocks; 648 std::swap(Blocks, CE.Blocks); 649 650 std::vector<llvm::BranchInst *> BranchFixups; 651 std::swap(BranchFixups, CE.BranchFixups); 652 653 bool EHOnly = CE.EHOnly; 654 655 setInvokeDest(CE.PreviousInvokeDest); 656 657 CleanupEntries.pop_back(); 658 659 // Check if any branch fixups pointed to the scope we just popped. If so, 660 // we can remove them. 661 for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) { 662 llvm::BasicBlock *Dest = BranchFixups[i]->getSuccessor(0); 663 BlockScopeMap::iterator I = BlockScopes.find(Dest); 664 665 if (I == BlockScopes.end()) 666 continue; 667 668 assert(I->second <= CleanupEntries.size() && "Invalid branch fixup!"); 669 670 if (I->second == CleanupEntries.size()) { 671 // We don't need to do this branch fixup. 672 BranchFixups[i] = BranchFixups.back(); 673 BranchFixups.pop_back(); 674 i--; 675 e--; 676 continue; 677 } 678 } 679 680 llvm::BasicBlock *SwitchBlock = CE.CleanupExitBlock; 681 llvm::BasicBlock *EndBlock = 0; 682 if (!BranchFixups.empty()) { 683 if (!SwitchBlock) 684 SwitchBlock = createBasicBlock("cleanup.switch"); 685 EndBlock = createBasicBlock("cleanup.end"); 686 687 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 688 689 Builder.SetInsertPoint(SwitchBlock); 690 691 llvm::Value *DestCodePtr 692 = CreateTempAlloca(llvm::Type::getInt32Ty(VMContext), 693 "cleanup.dst"); 694 llvm::Value *DestCode = Builder.CreateLoad(DestCodePtr, "tmp"); 695 696 // Create a switch instruction to determine where to jump next. 697 llvm::SwitchInst *SI = Builder.CreateSwitch(DestCode, EndBlock, 698 BranchFixups.size()); 699 700 // Restore the current basic block (if any) 701 if (CurBB) { 702 Builder.SetInsertPoint(CurBB); 703 704 // If we had a current basic block, we also need to emit an instruction 705 // to initialize the cleanup destination. 706 Builder.CreateStore(llvm::Constant::getNullValue(llvm::Type::getInt32Ty(VMContext)), 707 DestCodePtr); 708 } else 709 Builder.ClearInsertionPoint(); 710 711 for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) { 712 llvm::BranchInst *BI = BranchFixups[i]; 713 llvm::BasicBlock *Dest = BI->getSuccessor(0); 714 715 // Fixup the branch instruction to point to the cleanup block. 716 BI->setSuccessor(0, CleanupEntryBlock); 717 718 if (CleanupEntries.empty()) { 719 llvm::ConstantInt *ID; 720 721 // Check if we already have a destination for this block. 722 if (Dest == SI->getDefaultDest()) 723 ID = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 0); 724 else { 725 ID = SI->findCaseDest(Dest); 726 if (!ID) { 727 // No code found, get a new unique one by using the number of 728 // switch successors. 729 ID = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 730 SI->getNumSuccessors()); 731 SI->addCase(ID, Dest); 732 } 733 } 734 735 // Store the jump destination before the branch instruction. 736 new llvm::StoreInst(ID, DestCodePtr, BI); 737 } else { 738 // We need to jump through another cleanup block. Create a pad block 739 // with a branch instruction that jumps to the final destination and add 740 // it as a branch fixup to the current cleanup scope. 741 742 // Create the pad block. 743 llvm::BasicBlock *CleanupPad = createBasicBlock("cleanup.pad", CurFn); 744 745 // Create a unique case ID. 746 llvm::ConstantInt *ID 747 = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 748 SI->getNumSuccessors()); 749 750 // Store the jump destination before the branch instruction. 751 new llvm::StoreInst(ID, DestCodePtr, BI); 752 753 // Add it as the destination. 754 SI->addCase(ID, CleanupPad); 755 756 // Create the branch to the final destination. 757 llvm::BranchInst *BI = llvm::BranchInst::Create(Dest); 758 CleanupPad->getInstList().push_back(BI); 759 760 // And add it as a branch fixup. 761 CleanupEntries.back().BranchFixups.push_back(BI); 762 } 763 } 764 } 765 766 // Remove all blocks from the block scope map. 767 for (size_t i = 0, e = Blocks.size(); i != e; ++i) { 768 assert(BlockScopes.count(Blocks[i]) && 769 "Did not find block in scope map!"); 770 771 BlockScopes.erase(Blocks[i]); 772 } 773 774 return CleanupBlockInfo(CleanupEntryBlock, SwitchBlock, EndBlock, EHOnly); 775} 776 777void CodeGenFunction::EmitCleanupBlock() { 778 CleanupBlockInfo Info = PopCleanupBlock(); 779 780 if (Info.EHOnly) { 781 // FIXME: Add this to the exceptional edge 782 if (Info.CleanupBlock->getNumUses() == 0) 783 delete Info.CleanupBlock; 784 return; 785 } 786 787 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 788 if (CurBB && !CurBB->getTerminator() && 789 Info.CleanupBlock->getNumUses() == 0) { 790 CurBB->getInstList().splice(CurBB->end(), Info.CleanupBlock->getInstList()); 791 delete Info.CleanupBlock; 792 } else 793 EmitBlock(Info.CleanupBlock); 794 795 if (Info.SwitchBlock) 796 EmitBlock(Info.SwitchBlock); 797 if (Info.EndBlock) 798 EmitBlock(Info.EndBlock); 799} 800 801void CodeGenFunction::AddBranchFixup(llvm::BranchInst *BI) { 802 assert(!CleanupEntries.empty() && 803 "Trying to add branch fixup without cleanup block!"); 804 805 // FIXME: We could be more clever here and check if there's already a branch 806 // fixup for this destination and recycle it. 807 CleanupEntries.back().BranchFixups.push_back(BI); 808} 809 810void CodeGenFunction::EmitBranchThroughCleanup(llvm::BasicBlock *Dest) { 811 if (!HaveInsertPoint()) 812 return; 813 814 llvm::BranchInst* BI = Builder.CreateBr(Dest); 815 816 Builder.ClearInsertionPoint(); 817 818 // The stack is empty, no need to do any cleanup. 819 if (CleanupEntries.empty()) 820 return; 821 822 if (!Dest->getParent()) { 823 // We are trying to branch to a block that hasn't been inserted yet. 824 AddBranchFixup(BI); 825 return; 826 } 827 828 BlockScopeMap::iterator I = BlockScopes.find(Dest); 829 if (I == BlockScopes.end()) { 830 // We are trying to jump to a block that is outside of any cleanup scope. 831 AddBranchFixup(BI); 832 return; 833 } 834 835 assert(I->second < CleanupEntries.size() && 836 "Trying to branch into cleanup region"); 837 838 if (I->second == CleanupEntries.size() - 1) { 839 // We have a branch to a block in the same scope. 840 return; 841 } 842 843 AddBranchFixup(BI); 844} 845