CodeGenFunction.cpp revision 3019c444c672938c57f5573840071ecd73425ee7
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 "CGCXXABI.h" 17#include "CGDebugInfo.h" 18#include "CGException.h" 19#include "clang/Basic/TargetInfo.h" 20#include "clang/AST/APValue.h" 21#include "clang/AST/ASTContext.h" 22#include "clang/AST/Decl.h" 23#include "clang/AST/DeclCXX.h" 24#include "clang/AST/StmtCXX.h" 25#include "clang/Frontend/CodeGenOptions.h" 26#include "llvm/Target/TargetData.h" 27#include "llvm/Intrinsics.h" 28using namespace clang; 29using namespace CodeGen; 30 31CodeGenFunction::CodeGenFunction(CodeGenModule &cgm) 32 : BlockFunction(cgm, *this, Builder), CGM(cgm), 33 Target(CGM.getContext().Target), 34 Builder(cgm.getModule().getContext()), 35 NormalCleanupDest(0), EHCleanupDest(0), NextCleanupDestIndex(1), 36 ExceptionSlot(0), DebugInfo(0), IndirectBranch(0), 37 SwitchInsn(0), CaseRangeBlock(0), 38 DidCallStackSave(false), UnreachableBlock(0), 39 CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0), 40 ConditionalBranchLevel(0), TerminateLandingPad(0), TerminateHandler(0), 41 TrapBB(0) { 42 43 // Get some frequently used types. 44 LLVMPointerWidth = Target.getPointerWidth(0); 45 llvm::LLVMContext &LLVMContext = CGM.getLLVMContext(); 46 IntPtrTy = llvm::IntegerType::get(LLVMContext, LLVMPointerWidth); 47 Int32Ty = llvm::Type::getInt32Ty(LLVMContext); 48 Int64Ty = llvm::Type::getInt64Ty(LLVMContext); 49 50 Exceptions = getContext().getLangOptions().Exceptions; 51 CatchUndefined = getContext().getLangOptions().CatchUndefined; 52 CGM.getCXXABI().getMangleContext().startNewFunction(); 53} 54 55ASTContext &CodeGenFunction::getContext() const { 56 return CGM.getContext(); 57} 58 59 60const llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) { 61 return CGM.getTypes().ConvertTypeForMem(T); 62} 63 64const llvm::Type *CodeGenFunction::ConvertType(QualType T) { 65 return CGM.getTypes().ConvertType(T); 66} 67 68bool CodeGenFunction::hasAggregateLLVMType(QualType T) { 69 return T->isRecordType() || T->isArrayType() || T->isAnyComplexType() || 70 T->isObjCObjectType(); 71} 72 73void CodeGenFunction::EmitReturnBlock() { 74 // For cleanliness, we try to avoid emitting the return block for 75 // simple cases. 76 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 77 78 if (CurBB) { 79 assert(!CurBB->getTerminator() && "Unexpected terminated block."); 80 81 // We have a valid insert point, reuse it if it is empty or there are no 82 // explicit jumps to the return block. 83 if (CurBB->empty() || ReturnBlock.getBlock()->use_empty()) { 84 ReturnBlock.getBlock()->replaceAllUsesWith(CurBB); 85 delete ReturnBlock.getBlock(); 86 } else 87 EmitBlock(ReturnBlock.getBlock()); 88 return; 89 } 90 91 // Otherwise, if the return block is the target of a single direct 92 // branch then we can just put the code in that block instead. This 93 // cleans up functions which started with a unified return block. 94 if (ReturnBlock.getBlock()->hasOneUse()) { 95 llvm::BranchInst *BI = 96 dyn_cast<llvm::BranchInst>(*ReturnBlock.getBlock()->use_begin()); 97 if (BI && BI->isUnconditional() && 98 BI->getSuccessor(0) == ReturnBlock.getBlock()) { 99 // Reset insertion point and delete the branch. 100 Builder.SetInsertPoint(BI->getParent()); 101 BI->eraseFromParent(); 102 delete ReturnBlock.getBlock(); 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.getBlock()); 112} 113 114static void EmitIfUsed(CodeGenFunction &CGF, llvm::BasicBlock *BB) { 115 if (!BB) return; 116 if (!BB->use_empty()) 117 return CGF.CurFn->getBasicBlockList().push_back(BB); 118 delete BB; 119} 120 121void CodeGenFunction::FinishFunction(SourceLocation EndLoc) { 122 assert(BreakContinueStack.empty() && 123 "mismatched push/pop in break/continue stack!"); 124 125 // Emit function epilog (to return). 126 EmitReturnBlock(); 127 128 EmitFunctionInstrumentation("__cyg_profile_func_exit"); 129 130 // Emit debug descriptor for function end. 131 if (CGDebugInfo *DI = getDebugInfo()) { 132 DI->setLocation(EndLoc); 133 DI->EmitFunctionEnd(Builder); 134 } 135 136 EmitFunctionEpilog(*CurFnInfo); 137 EmitEndEHSpec(CurCodeDecl); 138 139 assert(EHStack.empty() && 140 "did not remove all scopes from cleanup stack!"); 141 142 // If someone did an indirect goto, emit the indirect goto block at the end of 143 // the function. 144 if (IndirectBranch) { 145 EmitBlock(IndirectBranch->getParent()); 146 Builder.ClearInsertionPoint(); 147 } 148 149 // Remove the AllocaInsertPt instruction, which is just a convenience for us. 150 llvm::Instruction *Ptr = AllocaInsertPt; 151 AllocaInsertPt = 0; 152 Ptr->eraseFromParent(); 153 154 // If someone took the address of a label but never did an indirect goto, we 155 // made a zero entry PHI node, which is illegal, zap it now. 156 if (IndirectBranch) { 157 llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress()); 158 if (PN->getNumIncomingValues() == 0) { 159 PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType())); 160 PN->eraseFromParent(); 161 } 162 } 163 164 EmitIfUsed(*this, RethrowBlock.getBlock()); 165 EmitIfUsed(*this, TerminateLandingPad); 166 EmitIfUsed(*this, TerminateHandler); 167 EmitIfUsed(*this, UnreachableBlock); 168 169 if (CGM.getCodeGenOpts().EmitDeclMetadata) 170 EmitDeclMetadata(); 171} 172 173/// ShouldInstrumentFunction - Return true if the current function should be 174/// instrumented with __cyg_profile_func_* calls 175bool CodeGenFunction::ShouldInstrumentFunction() { 176 if (!CGM.getCodeGenOpts().InstrumentFunctions) 177 return false; 178 if (CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>()) 179 return false; 180 return true; 181} 182 183/// EmitFunctionInstrumentation - Emit LLVM code to call the specified 184/// instrumentation function with the current function and the call site, if 185/// function instrumentation is enabled. 186void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) { 187 if (!ShouldInstrumentFunction()) 188 return; 189 190 const llvm::PointerType *PointerTy; 191 const llvm::FunctionType *FunctionTy; 192 std::vector<const llvm::Type*> ProfileFuncArgs; 193 194 // void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site); 195 PointerTy = llvm::Type::getInt8PtrTy(VMContext); 196 ProfileFuncArgs.push_back(PointerTy); 197 ProfileFuncArgs.push_back(PointerTy); 198 FunctionTy = llvm::FunctionType::get( 199 llvm::Type::getVoidTy(VMContext), 200 ProfileFuncArgs, false); 201 202 llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn); 203 llvm::CallInst *CallSite = Builder.CreateCall( 204 CGM.getIntrinsic(llvm::Intrinsic::returnaddress, 0, 0), 205 llvm::ConstantInt::get(Int32Ty, 0), 206 "callsite"); 207 208 Builder.CreateCall2(F, 209 llvm::ConstantExpr::getBitCast(CurFn, PointerTy), 210 CallSite); 211} 212 213void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy, 214 llvm::Function *Fn, 215 const FunctionArgList &Args, 216 SourceLocation StartLoc) { 217 const Decl *D = GD.getDecl(); 218 219 DidCallStackSave = false; 220 CurCodeDecl = CurFuncDecl = D; 221 FnRetTy = RetTy; 222 CurFn = Fn; 223 assert(CurFn->isDeclaration() && "Function already has body?"); 224 225 // Pass inline keyword to optimizer if it appears explicitly on any 226 // declaration. 227 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) 228 for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(), 229 RE = FD->redecls_end(); RI != RE; ++RI) 230 if (RI->isInlineSpecified()) { 231 Fn->addFnAttr(llvm::Attribute::InlineHint); 232 break; 233 } 234 235 llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn); 236 237 // Create a marker to make it easy to insert allocas into the entryblock 238 // later. Don't create this with the builder, because we don't want it 239 // folded. 240 llvm::Value *Undef = llvm::UndefValue::get(Int32Ty); 241 AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB); 242 if (Builder.isNamePreserving()) 243 AllocaInsertPt->setName("allocapt"); 244 245 ReturnBlock = getJumpDestInCurrentScope("return"); 246 247 Builder.SetInsertPoint(EntryBB); 248 249 QualType FnType = getContext().getFunctionType(RetTy, 0, 0, false, 0, 250 false, false, 0, 0, 251 /*FIXME?*/ 252 FunctionType::ExtInfo()); 253 254 // Emit subprogram debug descriptor. 255 if (CGDebugInfo *DI = getDebugInfo()) { 256 DI->setLocation(StartLoc); 257 DI->EmitFunctionStart(GD, FnType, CurFn, Builder); 258 } 259 260 EmitFunctionInstrumentation("__cyg_profile_func_enter"); 261 262 // FIXME: Leaked. 263 // CC info is ignored, hopefully? 264 CurFnInfo = &CGM.getTypes().getFunctionInfo(FnRetTy, Args, 265 FunctionType::ExtInfo()); 266 267 if (RetTy->isVoidType()) { 268 // Void type; nothing to return. 269 ReturnValue = 0; 270 } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect && 271 hasAggregateLLVMType(CurFnInfo->getReturnType())) { 272 // Indirect aggregate return; emit returned value directly into sret slot. 273 // This reduces code size, and affects correctness in C++. 274 ReturnValue = CurFn->arg_begin(); 275 } else { 276 ReturnValue = CreateIRTemp(RetTy, "retval"); 277 } 278 279 EmitStartEHSpec(CurCodeDecl); 280 EmitFunctionProlog(*CurFnInfo, CurFn, Args); 281 282 if (D && isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance()) 283 CGM.getCXXABI().EmitInstanceFunctionProlog(*this); 284 285 // If any of the arguments have a variably modified type, make sure to 286 // emit the type size. 287 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); 288 i != e; ++i) { 289 QualType Ty = i->second; 290 291 if (Ty->isVariablyModifiedType()) 292 EmitVLASize(Ty); 293 } 294} 295 296void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) { 297 const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl()); 298 assert(FD->getBody()); 299 EmitStmt(FD->getBody()); 300} 301 302/// Tries to mark the given function nounwind based on the 303/// non-existence of any throwing calls within it. We believe this is 304/// lightweight enough to do at -O0. 305static void TryMarkNoThrow(llvm::Function *F) { 306 // LLVM treats 'nounwind' on a function as part of the type, so we 307 // can't do this on functions that can be overwritten. 308 if (F->mayBeOverridden()) return; 309 310 for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI) 311 for (llvm::BasicBlock::iterator 312 BI = FI->begin(), BE = FI->end(); BI != BE; ++BI) 313 if (llvm::CallInst *Call = dyn_cast<llvm::CallInst>(&*BI)) 314 if (!Call->doesNotThrow()) 315 return; 316 F->setDoesNotThrow(true); 317} 318 319void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn) { 320 const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl()); 321 322 // Check if we should generate debug info for this function. 323 if (CGM.getDebugInfo() && !FD->hasAttr<NoDebugAttr>()) 324 DebugInfo = CGM.getDebugInfo(); 325 326 FunctionArgList Args; 327 QualType ResTy = FD->getResultType(); 328 329 CurGD = GD; 330 if (isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isInstance()) 331 CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args); 332 333 if (FD->getNumParams()) { 334 const FunctionProtoType* FProto = FD->getType()->getAs<FunctionProtoType>(); 335 assert(FProto && "Function def must have prototype!"); 336 337 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) 338 Args.push_back(std::make_pair(FD->getParamDecl(i), 339 FProto->getArgType(i))); 340 } 341 342 SourceRange BodyRange; 343 if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange(); 344 345 // Emit the standard function prologue. 346 StartFunction(GD, ResTy, Fn, Args, BodyRange.getBegin()); 347 348 // Generate the body of the function. 349 if (isa<CXXDestructorDecl>(FD)) 350 EmitDestructorBody(Args); 351 else if (isa<CXXConstructorDecl>(FD)) 352 EmitConstructorBody(Args); 353 else 354 EmitFunctionBody(Args); 355 356 // Emit the standard function epilogue. 357 FinishFunction(BodyRange.getEnd()); 358 359 // If we haven't marked the function nothrow through other means, do 360 // a quick pass now to see if we can. 361 if (!CurFn->doesNotThrow()) 362 TryMarkNoThrow(CurFn); 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() == BO_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() == BO_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() == UO_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 520CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) { 521 // Ignore empty classes in C++. 522 if (getContext().getLangOptions().CPlusPlus) { 523 if (const RecordType *RT = Ty->getAs<RecordType>()) { 524 if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty()) 525 return; 526 } 527 } 528 529 // Cast the dest ptr to the appropriate i8 pointer type. 530 unsigned DestAS = 531 cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace(); 532 const llvm::Type *BP = 533 llvm::Type::getInt8PtrTy(VMContext, DestAS); 534 if (DestPtr->getType() != BP) 535 DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); 536 537 // Get size and alignment info for this aggregate. 538 std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); 539 uint64_t Size = TypeInfo.first; 540 unsigned Align = TypeInfo.second; 541 542 // Don't bother emitting a zero-byte memset. 543 if (Size == 0) 544 return; 545 546 llvm::ConstantInt *SizeVal = llvm::ConstantInt::get(IntPtrTy, Size / 8); 547 llvm::ConstantInt *AlignVal = Builder.getInt32(Align / 8); 548 549 // If the type contains a pointer to data member we can't memset it to zero. 550 // Instead, create a null constant and copy it to the destination. 551 if (!CGM.getTypes().isZeroInitializable(Ty)) { 552 llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty); 553 554 llvm::GlobalVariable *NullVariable = 555 new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(), 556 /*isConstant=*/true, 557 llvm::GlobalVariable::PrivateLinkage, 558 NullConstant, llvm::Twine()); 559 llvm::Value *SrcPtr = 560 Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy()); 561 562 // FIXME: variable-size types? 563 564 // Get and call the appropriate llvm.memcpy overload. 565 llvm::Constant *Memcpy = 566 CGM.getMemCpyFn(DestPtr->getType(), SrcPtr->getType(), IntPtrTy); 567 Builder.CreateCall5(Memcpy, DestPtr, SrcPtr, SizeVal, AlignVal, 568 /*volatile*/ Builder.getFalse()); 569 return; 570 } 571 572 // Otherwise, just memset the whole thing to zero. This is legal 573 // because in LLVM, all default initializers (other than the ones we just 574 // handled above) are guaranteed to have a bit pattern of all zeros. 575 576 // FIXME: Handle variable sized types. 577 Builder.CreateCall5(CGM.getMemSetFn(BP, IntPtrTy), DestPtr, 578 Builder.getInt8(0), 579 SizeVal, AlignVal, /*volatile*/ Builder.getFalse()); 580} 581 582llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelStmt *L) { 583 // Make sure that there is a block for the indirect goto. 584 if (IndirectBranch == 0) 585 GetIndirectGotoBlock(); 586 587 llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock(); 588 589 // Make sure the indirect branch includes all of the address-taken blocks. 590 IndirectBranch->addDestination(BB); 591 return llvm::BlockAddress::get(CurFn, BB); 592} 593 594llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() { 595 // If we already made the indirect branch for indirect goto, return its block. 596 if (IndirectBranch) return IndirectBranch->getParent(); 597 598 CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto")); 599 600 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext); 601 602 // Create the PHI node that indirect gotos will add entries to. 603 llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, "indirect.goto.dest"); 604 605 // Create the indirect branch instruction. 606 IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal); 607 return IndirectBranch->getParent(); 608} 609 610llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) { 611 llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; 612 613 assert(SizeEntry && "Did not emit size for type"); 614 return SizeEntry; 615} 616 617llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) { 618 assert(Ty->isVariablyModifiedType() && 619 "Must pass variably modified type to EmitVLASizes!"); 620 621 EnsureInsertPoint(); 622 623 if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) { 624 llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; 625 626 if (!SizeEntry) { 627 const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); 628 629 // Get the element size; 630 QualType ElemTy = VAT->getElementType(); 631 llvm::Value *ElemSize; 632 if (ElemTy->isVariableArrayType()) 633 ElemSize = EmitVLASize(ElemTy); 634 else 635 ElemSize = llvm::ConstantInt::get(SizeTy, 636 getContext().getTypeSizeInChars(ElemTy).getQuantity()); 637 638 llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr()); 639 NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp"); 640 641 SizeEntry = Builder.CreateMul(ElemSize, NumElements); 642 } 643 644 return SizeEntry; 645 } 646 647 if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) { 648 EmitVLASize(AT->getElementType()); 649 return 0; 650 } 651 652 const PointerType *PT = Ty->getAs<PointerType>(); 653 assert(PT && "unknown VM type!"); 654 EmitVLASize(PT->getPointeeType()); 655 return 0; 656} 657 658llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { 659 if (CGM.getContext().getBuiltinVaListType()->isArrayType()) 660 return EmitScalarExpr(E); 661 return EmitLValue(E).getAddress(); 662} 663 664/// Pops cleanup blocks until the given savepoint is reached. 665void CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old) { 666 assert(Old.isValid()); 667 668 while (EHStack.stable_begin() != Old) { 669 EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin()); 670 671 // As long as Old strictly encloses the scope's enclosing normal 672 // cleanup, we're going to emit another normal cleanup which 673 // fallthrough can propagate through. 674 bool FallThroughIsBranchThrough = 675 Old.strictlyEncloses(Scope.getEnclosingNormalCleanup()); 676 677 PopCleanupBlock(FallThroughIsBranchThrough); 678 } 679} 680 681static llvm::BasicBlock *CreateNormalEntry(CodeGenFunction &CGF, 682 EHCleanupScope &Scope) { 683 assert(Scope.isNormalCleanup()); 684 llvm::BasicBlock *Entry = Scope.getNormalBlock(); 685 if (!Entry) { 686 Entry = CGF.createBasicBlock("cleanup"); 687 Scope.setNormalBlock(Entry); 688 } 689 return Entry; 690} 691 692static llvm::BasicBlock *CreateEHEntry(CodeGenFunction &CGF, 693 EHCleanupScope &Scope) { 694 assert(Scope.isEHCleanup()); 695 llvm::BasicBlock *Entry = Scope.getEHBlock(); 696 if (!Entry) { 697 Entry = CGF.createBasicBlock("eh.cleanup"); 698 Scope.setEHBlock(Entry); 699 } 700 return Entry; 701} 702 703/// Transitions the terminator of the given exit-block of a cleanup to 704/// be a cleanup switch. 705static llvm::SwitchInst *TransitionToCleanupSwitch(CodeGenFunction &CGF, 706 llvm::BasicBlock *Block) { 707 // If it's a branch, turn it into a switch whose default 708 // destination is its original target. 709 llvm::TerminatorInst *Term = Block->getTerminator(); 710 assert(Term && "can't transition block without terminator"); 711 712 if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) { 713 assert(Br->isUnconditional()); 714 llvm::LoadInst *Load = 715 new llvm::LoadInst(CGF.getNormalCleanupDestSlot(), "cleanup.dest", Term); 716 llvm::SwitchInst *Switch = 717 llvm::SwitchInst::Create(Load, Br->getSuccessor(0), 4, Block); 718 Br->eraseFromParent(); 719 return Switch; 720 } else { 721 return cast<llvm::SwitchInst>(Term); 722 } 723} 724 725/// Attempts to reduce a cleanup's entry block to a fallthrough. This 726/// is basically llvm::MergeBlockIntoPredecessor, except 727/// simplified/optimized for the tighter constraints on cleanup blocks. 728/// 729/// Returns the new block, whatever it is. 730static llvm::BasicBlock *SimplifyCleanupEntry(CodeGenFunction &CGF, 731 llvm::BasicBlock *Entry) { 732 llvm::BasicBlock *Pred = Entry->getSinglePredecessor(); 733 if (!Pred) return Entry; 734 735 llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Pred->getTerminator()); 736 if (!Br || Br->isConditional()) return Entry; 737 assert(Br->getSuccessor(0) == Entry); 738 739 // If we were previously inserting at the end of the cleanup entry 740 // block, we'll need to continue inserting at the end of the 741 // predecessor. 742 bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry; 743 assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end()); 744 745 // Kill the branch. 746 Br->eraseFromParent(); 747 748 // Merge the blocks. 749 Pred->getInstList().splice(Pred->end(), Entry->getInstList()); 750 751 // Kill the entry block. 752 Entry->eraseFromParent(); 753 754 if (WasInsertBlock) 755 CGF.Builder.SetInsertPoint(Pred); 756 757 return Pred; 758} 759 760static void EmitCleanup(CodeGenFunction &CGF, 761 EHScopeStack::Cleanup *Fn, 762 bool ForEH, 763 llvm::Value *ActiveFlag) { 764 // EH cleanups always occur within a terminate scope. 765 if (ForEH) CGF.EHStack.pushTerminate(); 766 767 // If there's an active flag, load it and skip the cleanup if it's 768 // false. 769 llvm::BasicBlock *ContBB = 0; 770 if (ActiveFlag) { 771 ContBB = CGF.createBasicBlock("cleanup.done"); 772 llvm::BasicBlock *CleanupBB = CGF.createBasicBlock("cleanup.action"); 773 llvm::Value *IsActive 774 = CGF.Builder.CreateLoad(ActiveFlag, "cleanup.is_active"); 775 CGF.Builder.CreateCondBr(IsActive, CleanupBB, ContBB); 776 CGF.EmitBlock(CleanupBB); 777 } 778 779 // Ask the cleanup to emit itself. 780 Fn->Emit(CGF, ForEH); 781 assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?"); 782 783 // Emit the continuation block if there was an active flag. 784 if (ActiveFlag) 785 CGF.EmitBlock(ContBB); 786 787 // Leave the terminate scope. 788 if (ForEH) CGF.EHStack.popTerminate(); 789} 790 791static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit, 792 llvm::BasicBlock *From, 793 llvm::BasicBlock *To) { 794 // Exit is the exit block of a cleanup, so it always terminates in 795 // an unconditional branch or a switch. 796 llvm::TerminatorInst *Term = Exit->getTerminator(); 797 798 if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) { 799 assert(Br->isUnconditional() && Br->getSuccessor(0) == From); 800 Br->setSuccessor(0, To); 801 } else { 802 llvm::SwitchInst *Switch = cast<llvm::SwitchInst>(Term); 803 for (unsigned I = 0, E = Switch->getNumSuccessors(); I != E; ++I) 804 if (Switch->getSuccessor(I) == From) 805 Switch->setSuccessor(I, To); 806 } 807} 808 809/// Pops a cleanup block. If the block includes a normal cleanup, the 810/// current insertion point is threaded through the cleanup, as are 811/// any branch fixups on the cleanup. 812void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) { 813 assert(!EHStack.empty() && "cleanup stack is empty!"); 814 assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!"); 815 EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin()); 816 assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups()); 817 818 // Remember activation information. 819 bool IsActive = Scope.isActive(); 820 llvm::Value *NormalActiveFlag = 821 Scope.shouldTestFlagInNormalCleanup() ? Scope.getActiveFlag() : 0; 822 llvm::Value *EHActiveFlag = 823 Scope.shouldTestFlagInEHCleanup() ? Scope.getActiveFlag() : 0; 824 825 // Check whether we need an EH cleanup. This is only true if we've 826 // generated a lazy EH cleanup block. 827 bool RequiresEHCleanup = Scope.hasEHBranches(); 828 829 // Check the three conditions which might require a normal cleanup: 830 831 // - whether there are branch fix-ups through this cleanup 832 unsigned FixupDepth = Scope.getFixupDepth(); 833 bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth; 834 835 // - whether there are branch-throughs or branch-afters 836 bool HasExistingBranches = Scope.hasBranches(); 837 838 // - whether there's a fallthrough 839 llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock(); 840 bool HasFallthrough = (FallthroughSource != 0 && IsActive); 841 842 // As a kindof crazy internal case, branch-through fall-throughs 843 // leave the insertion point set to the end of the last cleanup. 844 bool HasPrebranchedFallthrough = 845 (FallthroughSource && FallthroughSource->getTerminator()); 846 847 bool RequiresNormalCleanup = false; 848 if (Scope.isNormalCleanup() && 849 (HasFixups || HasExistingBranches || HasFallthrough)) { 850 RequiresNormalCleanup = true; 851 } 852 853 assert(!HasPrebranchedFallthrough || RequiresNormalCleanup || !IsActive); 854 assert(!HasPrebranchedFallthrough || 855 (Scope.isNormalCleanup() && Scope.getNormalBlock() && 856 FallthroughSource->getTerminator()->getSuccessor(0) 857 == Scope.getNormalBlock())); 858 859 // Even if we don't need the normal cleanup, we might still have 860 // prebranched fallthrough to worry about. 861 if (!RequiresNormalCleanup && HasPrebranchedFallthrough) { 862 assert(!IsActive); 863 864 llvm::BasicBlock *NormalEntry = Scope.getNormalBlock(); 865 866 // If we're branching through this cleanup, just forward the 867 // prebranched fallthrough to the next cleanup, leaving the insert 868 // point in the old block. 869 if (FallthroughIsBranchThrough) { 870 EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup()); 871 llvm::BasicBlock *EnclosingEntry = 872 CreateNormalEntry(*this, cast<EHCleanupScope>(S)); 873 874 ForwardPrebranchedFallthrough(FallthroughSource, 875 NormalEntry, EnclosingEntry); 876 assert(NormalEntry->use_empty() && 877 "uses of entry remain after forwarding?"); 878 delete NormalEntry; 879 880 // Otherwise, we're branching out; just emit the next block. 881 } else { 882 EmitBlock(NormalEntry); 883 SimplifyCleanupEntry(*this, NormalEntry); 884 } 885 } 886 887 // If we don't need the cleanup at all, we're done. 888 if (!RequiresNormalCleanup && !RequiresEHCleanup) { 889 EHStack.popCleanup(); // safe because there are no fixups 890 assert(EHStack.getNumBranchFixups() == 0 || 891 EHStack.hasNormalCleanups()); 892 return; 893 } 894 895 // Copy the cleanup emission data out. Note that SmallVector 896 // guarantees maximal alignment for its buffer regardless of its 897 // type parameter. 898 llvm::SmallVector<char, 8*sizeof(void*)> CleanupBuffer; 899 CleanupBuffer.reserve(Scope.getCleanupSize()); 900 memcpy(CleanupBuffer.data(), 901 Scope.getCleanupBuffer(), Scope.getCleanupSize()); 902 CleanupBuffer.set_size(Scope.getCleanupSize()); 903 EHScopeStack::Cleanup *Fn = 904 reinterpret_cast<EHScopeStack::Cleanup*>(CleanupBuffer.data()); 905 906 // We want to emit the EH cleanup after the normal cleanup, but go 907 // ahead and do the setup for the EH cleanup while the scope is still 908 // alive. 909 llvm::BasicBlock *EHEntry = 0; 910 llvm::SmallVector<llvm::Instruction*, 2> EHInstsToAppend; 911 if (RequiresEHCleanup) { 912 EHEntry = CreateEHEntry(*this, Scope); 913 914 // Figure out the branch-through dest if necessary. 915 llvm::BasicBlock *EHBranchThroughDest = 0; 916 if (Scope.hasEHBranchThroughs()) { 917 assert(Scope.getEnclosingEHCleanup() != EHStack.stable_end()); 918 EHScope &S = *EHStack.find(Scope.getEnclosingEHCleanup()); 919 EHBranchThroughDest = CreateEHEntry(*this, cast<EHCleanupScope>(S)); 920 } 921 922 // If we have exactly one branch-after and no branch-throughs, we 923 // can dispatch it without a switch. 924 if (!Scope.hasEHBranchThroughs() && 925 Scope.getNumEHBranchAfters() == 1) { 926 assert(!EHBranchThroughDest); 927 928 // TODO: remove the spurious eh.cleanup.dest stores if this edge 929 // never went through any switches. 930 llvm::BasicBlock *BranchAfterDest = Scope.getEHBranchAfterBlock(0); 931 EHInstsToAppend.push_back(llvm::BranchInst::Create(BranchAfterDest)); 932 933 // Otherwise, if we have any branch-afters, we need a switch. 934 } else if (Scope.getNumEHBranchAfters()) { 935 // The default of the switch belongs to the branch-throughs if 936 // they exist. 937 llvm::BasicBlock *Default = 938 (EHBranchThroughDest ? EHBranchThroughDest : getUnreachableBlock()); 939 940 const unsigned SwitchCapacity = Scope.getNumEHBranchAfters(); 941 942 llvm::LoadInst *Load = 943 new llvm::LoadInst(getEHCleanupDestSlot(), "cleanup.dest"); 944 llvm::SwitchInst *Switch = 945 llvm::SwitchInst::Create(Load, Default, SwitchCapacity); 946 947 EHInstsToAppend.push_back(Load); 948 EHInstsToAppend.push_back(Switch); 949 950 for (unsigned I = 0, E = Scope.getNumEHBranchAfters(); I != E; ++I) 951 Switch->addCase(Scope.getEHBranchAfterIndex(I), 952 Scope.getEHBranchAfterBlock(I)); 953 954 // Otherwise, we have only branch-throughs; jump to the next EH 955 // cleanup. 956 } else { 957 assert(EHBranchThroughDest); 958 EHInstsToAppend.push_back(llvm::BranchInst::Create(EHBranchThroughDest)); 959 } 960 } 961 962 if (!RequiresNormalCleanup) { 963 EHStack.popCleanup(); 964 } else { 965 // If we have a fallthrough and no other need for the cleanup, 966 // emit it directly. 967 if (HasFallthrough && !HasPrebranchedFallthrough && 968 !HasFixups && !HasExistingBranches) { 969 970 // Fixups can cause us to optimistically create a normal block, 971 // only to later have no real uses for it. Just delete it in 972 // this case. 973 // TODO: we can potentially simplify all the uses after this. 974 if (Scope.getNormalBlock()) { 975 Scope.getNormalBlock()->replaceAllUsesWith(getUnreachableBlock()); 976 delete Scope.getNormalBlock(); 977 } 978 979 EHStack.popCleanup(); 980 981 EmitCleanup(*this, Fn, /*ForEH*/ false, NormalActiveFlag); 982 983 // Otherwise, the best approach is to thread everything through 984 // the cleanup block and then try to clean up after ourselves. 985 } else { 986 // Force the entry block to exist. 987 llvm::BasicBlock *NormalEntry = CreateNormalEntry(*this, Scope); 988 989 // I. Set up the fallthrough edge in. 990 991 // If there's a fallthrough, we need to store the cleanup 992 // destination index. For fall-throughs this is always zero. 993 if (HasFallthrough) { 994 if (!HasPrebranchedFallthrough) 995 Builder.CreateStore(Builder.getInt32(0), getNormalCleanupDestSlot()); 996 997 // Otherwise, clear the IP if we don't have fallthrough because 998 // the cleanup is inactive. We don't need to save it because 999 // it's still just FallthroughSource. 1000 } else if (FallthroughSource) { 1001 assert(!IsActive && "source without fallthrough for active cleanup"); 1002 Builder.ClearInsertionPoint(); 1003 } 1004 1005 // II. Emit the entry block. This implicitly branches to it if 1006 // we have fallthrough. All the fixups and existing branches 1007 // should already be branched to it. 1008 EmitBlock(NormalEntry); 1009 1010 // III. Figure out where we're going and build the cleanup 1011 // epilogue. 1012 1013 bool HasEnclosingCleanups = 1014 (Scope.getEnclosingNormalCleanup() != EHStack.stable_end()); 1015 1016 // Compute the branch-through dest if we need it: 1017 // - if there are branch-throughs threaded through the scope 1018 // - if fall-through is a branch-through 1019 // - if there are fixups that will be optimistically forwarded 1020 // to the enclosing cleanup 1021 llvm::BasicBlock *BranchThroughDest = 0; 1022 if (Scope.hasBranchThroughs() || 1023 (FallthroughSource && FallthroughIsBranchThrough) || 1024 (HasFixups && HasEnclosingCleanups)) { 1025 assert(HasEnclosingCleanups); 1026 EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup()); 1027 BranchThroughDest = CreateNormalEntry(*this, cast<EHCleanupScope>(S)); 1028 } 1029 1030 llvm::BasicBlock *FallthroughDest = 0; 1031 llvm::SmallVector<llvm::Instruction*, 2> InstsToAppend; 1032 1033 // If there's exactly one branch-after and no other threads, 1034 // we can route it without a switch. 1035 if (!Scope.hasBranchThroughs() && !HasFixups && !HasFallthrough && 1036 Scope.getNumBranchAfters() == 1) { 1037 assert(!BranchThroughDest || !IsActive); 1038 1039 // TODO: clean up the possibly dead stores to the cleanup dest slot. 1040 llvm::BasicBlock *BranchAfter = Scope.getBranchAfterBlock(0); 1041 InstsToAppend.push_back(llvm::BranchInst::Create(BranchAfter)); 1042 1043 // Build a switch-out if we need it: 1044 // - if there are branch-afters threaded through the scope 1045 // - if fall-through is a branch-after 1046 // - if there are fixups that have nowhere left to go and 1047 // so must be immediately resolved 1048 } else if (Scope.getNumBranchAfters() || 1049 (HasFallthrough && !FallthroughIsBranchThrough) || 1050 (HasFixups && !HasEnclosingCleanups)) { 1051 1052 llvm::BasicBlock *Default = 1053 (BranchThroughDest ? BranchThroughDest : getUnreachableBlock()); 1054 1055 // TODO: base this on the number of branch-afters and fixups 1056 const unsigned SwitchCapacity = 10; 1057 1058 llvm::LoadInst *Load = 1059 new llvm::LoadInst(getNormalCleanupDestSlot(), "cleanup.dest"); 1060 llvm::SwitchInst *Switch = 1061 llvm::SwitchInst::Create(Load, Default, SwitchCapacity); 1062 1063 InstsToAppend.push_back(Load); 1064 InstsToAppend.push_back(Switch); 1065 1066 // Branch-after fallthrough. 1067 if (FallthroughSource && !FallthroughIsBranchThrough) { 1068 FallthroughDest = createBasicBlock("cleanup.cont"); 1069 if (HasFallthrough) 1070 Switch->addCase(Builder.getInt32(0), FallthroughDest); 1071 } 1072 1073 for (unsigned I = 0, E = Scope.getNumBranchAfters(); I != E; ++I) { 1074 Switch->addCase(Scope.getBranchAfterIndex(I), 1075 Scope.getBranchAfterBlock(I)); 1076 } 1077 1078 if (HasFixups && !HasEnclosingCleanups) 1079 ResolveAllBranchFixups(Switch); 1080 } else { 1081 // We should always have a branch-through destination in this case. 1082 assert(BranchThroughDest); 1083 InstsToAppend.push_back(llvm::BranchInst::Create(BranchThroughDest)); 1084 } 1085 1086 // IV. Pop the cleanup and emit it. 1087 EHStack.popCleanup(); 1088 assert(EHStack.hasNormalCleanups() == HasEnclosingCleanups); 1089 1090 EmitCleanup(*this, Fn, /*ForEH*/ false, NormalActiveFlag); 1091 1092 // Append the prepared cleanup prologue from above. 1093 llvm::BasicBlock *NormalExit = Builder.GetInsertBlock(); 1094 for (unsigned I = 0, E = InstsToAppend.size(); I != E; ++I) 1095 NormalExit->getInstList().push_back(InstsToAppend[I]); 1096 1097 // Optimistically hope that any fixups will continue falling through. 1098 for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups(); 1099 I < E; ++I) { 1100 BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I); 1101 if (!Fixup.Destination) continue; 1102 if (!Fixup.OptimisticBranchBlock) { 1103 new llvm::StoreInst(Builder.getInt32(Fixup.DestinationIndex), 1104 getNormalCleanupDestSlot(), 1105 Fixup.InitialBranch); 1106 Fixup.InitialBranch->setSuccessor(0, NormalEntry); 1107 } 1108 Fixup.OptimisticBranchBlock = NormalExit; 1109 } 1110 1111 // V. Set up the fallthrough edge out. 1112 1113 // Case 1: a fallthrough source exists but shouldn't branch to 1114 // the cleanup because the cleanup is inactive. 1115 if (!HasFallthrough && FallthroughSource) { 1116 assert(!IsActive); 1117 1118 // If we have a prebranched fallthrough, that needs to be 1119 // forwarded to the right block. 1120 if (HasPrebranchedFallthrough) { 1121 llvm::BasicBlock *Next; 1122 if (FallthroughIsBranchThrough) { 1123 Next = BranchThroughDest; 1124 assert(!FallthroughDest); 1125 } else { 1126 Next = FallthroughDest; 1127 } 1128 1129 ForwardPrebranchedFallthrough(FallthroughSource, NormalEntry, Next); 1130 } 1131 Builder.SetInsertPoint(FallthroughSource); 1132 1133 // Case 2: a fallthrough source exists and should branch to the 1134 // cleanup, but we're not supposed to branch through to the next 1135 // cleanup. 1136 } else if (HasFallthrough && FallthroughDest) { 1137 assert(!FallthroughIsBranchThrough); 1138 EmitBlock(FallthroughDest); 1139 1140 // Case 3: a fallthrough source exists and should branch to the 1141 // cleanup and then through to the next. 1142 } else if (HasFallthrough) { 1143 // Everything is already set up for this. 1144 1145 // Case 4: no fallthrough source exists. 1146 } else { 1147 Builder.ClearInsertionPoint(); 1148 } 1149 1150 // VI. Assorted cleaning. 1151 1152 // Check whether we can merge NormalEntry into a single predecessor. 1153 // This might invalidate (non-IR) pointers to NormalEntry. 1154 llvm::BasicBlock *NewNormalEntry = 1155 SimplifyCleanupEntry(*this, NormalEntry); 1156 1157 // If it did invalidate those pointers, and NormalEntry was the same 1158 // as NormalExit, go back and patch up the fixups. 1159 if (NewNormalEntry != NormalEntry && NormalEntry == NormalExit) 1160 for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups(); 1161 I < E; ++I) 1162 CGF.EHStack.getBranchFixup(I).OptimisticBranchBlock = NewNormalEntry; 1163 } 1164 } 1165 1166 assert(EHStack.hasNormalCleanups() || EHStack.getNumBranchFixups() == 0); 1167 1168 // Emit the EH cleanup if required. 1169 if (RequiresEHCleanup) { 1170 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP(); 1171 1172 EmitBlock(EHEntry); 1173 EmitCleanup(*this, Fn, /*ForEH*/ true, EHActiveFlag); 1174 1175 // Append the prepared cleanup prologue from above. 1176 llvm::BasicBlock *EHExit = Builder.GetInsertBlock(); 1177 for (unsigned I = 0, E = EHInstsToAppend.size(); I != E; ++I) 1178 EHExit->getInstList().push_back(EHInstsToAppend[I]); 1179 1180 Builder.restoreIP(SavedIP); 1181 1182 SimplifyCleanupEntry(*this, EHEntry); 1183 } 1184} 1185 1186/// Terminate the current block by emitting a branch which might leave 1187/// the current cleanup-protected scope. The target scope may not yet 1188/// be known, in which case this will require a fixup. 1189/// 1190/// As a side-effect, this method clears the insertion point. 1191void CodeGenFunction::EmitBranchThroughCleanup(JumpDest Dest) { 1192 assert(Dest.getScopeDepth().encloses(EHStack.getInnermostNormalCleanup()) 1193 && "stale jump destination"); 1194 1195 if (!HaveInsertPoint()) 1196 return; 1197 1198 // Create the branch. 1199 llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock()); 1200 1201 // Calculate the innermost active normal cleanup. 1202 EHScopeStack::stable_iterator 1203 TopCleanup = EHStack.getInnermostActiveNormalCleanup(); 1204 1205 // If we're not in an active normal cleanup scope, or if the 1206 // destination scope is within the innermost active normal cleanup 1207 // scope, we don't need to worry about fixups. 1208 if (TopCleanup == EHStack.stable_end() || 1209 TopCleanup.encloses(Dest.getScopeDepth())) { // works for invalid 1210 Builder.ClearInsertionPoint(); 1211 return; 1212 } 1213 1214 // If we can't resolve the destination cleanup scope, just add this 1215 // to the current cleanup scope as a branch fixup. 1216 if (!Dest.getScopeDepth().isValid()) { 1217 BranchFixup &Fixup = EHStack.addBranchFixup(); 1218 Fixup.Destination = Dest.getBlock(); 1219 Fixup.DestinationIndex = Dest.getDestIndex(); 1220 Fixup.InitialBranch = BI; 1221 Fixup.OptimisticBranchBlock = 0; 1222 1223 Builder.ClearInsertionPoint(); 1224 return; 1225 } 1226 1227 // Otherwise, thread through all the normal cleanups in scope. 1228 1229 // Store the index at the start. 1230 llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex()); 1231 new llvm::StoreInst(Index, getNormalCleanupDestSlot(), BI); 1232 1233 // Adjust BI to point to the first cleanup block. 1234 { 1235 EHCleanupScope &Scope = 1236 cast<EHCleanupScope>(*EHStack.find(TopCleanup)); 1237 BI->setSuccessor(0, CreateNormalEntry(*this, Scope)); 1238 } 1239 1240 // Add this destination to all the scopes involved. 1241 EHScopeStack::stable_iterator I = TopCleanup; 1242 EHScopeStack::stable_iterator E = Dest.getScopeDepth(); 1243 if (E.strictlyEncloses(I)) { 1244 while (true) { 1245 EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I)); 1246 assert(Scope.isNormalCleanup()); 1247 I = Scope.getEnclosingNormalCleanup(); 1248 1249 // If this is the last cleanup we're propagating through, tell it 1250 // that there's a resolved jump moving through it. 1251 if (!E.strictlyEncloses(I)) { 1252 Scope.addBranchAfter(Index, Dest.getBlock()); 1253 break; 1254 } 1255 1256 // Otherwise, tell the scope that there's a jump propoagating 1257 // through it. If this isn't new information, all the rest of 1258 // the work has been done before. 1259 if (!Scope.addBranchThrough(Dest.getBlock())) 1260 break; 1261 } 1262 } 1263 1264 Builder.ClearInsertionPoint(); 1265} 1266 1267void CodeGenFunction::EmitBranchThroughEHCleanup(UnwindDest Dest) { 1268 // We should never get invalid scope depths for an UnwindDest; that 1269 // implies that the destination wasn't set up correctly. 1270 assert(Dest.getScopeDepth().isValid() && "invalid scope depth on EH dest?"); 1271 1272 if (!HaveInsertPoint()) 1273 return; 1274 1275 // Create the branch. 1276 llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock()); 1277 1278 // Calculate the innermost active cleanup. 1279 EHScopeStack::stable_iterator 1280 InnermostCleanup = EHStack.getInnermostActiveEHCleanup(); 1281 1282 // If the destination is in the same EH cleanup scope as us, we 1283 // don't need to thread through anything. 1284 if (InnermostCleanup.encloses(Dest.getScopeDepth())) { 1285 Builder.ClearInsertionPoint(); 1286 return; 1287 } 1288 assert(InnermostCleanup != EHStack.stable_end()); 1289 1290 // Store the index at the start. 1291 llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex()); 1292 new llvm::StoreInst(Index, getEHCleanupDestSlot(), BI); 1293 1294 // Adjust BI to point to the first cleanup block. 1295 { 1296 EHCleanupScope &Scope = 1297 cast<EHCleanupScope>(*EHStack.find(InnermostCleanup)); 1298 BI->setSuccessor(0, CreateEHEntry(*this, Scope)); 1299 } 1300 1301 // Add this destination to all the scopes involved. 1302 for (EHScopeStack::stable_iterator 1303 I = InnermostCleanup, E = Dest.getScopeDepth(); ; ) { 1304 assert(E.strictlyEncloses(I)); 1305 EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I)); 1306 assert(Scope.isEHCleanup()); 1307 I = Scope.getEnclosingEHCleanup(); 1308 1309 // If this is the last cleanup we're propagating through, add this 1310 // as a branch-after. 1311 if (I == E) { 1312 Scope.addEHBranchAfter(Index, Dest.getBlock()); 1313 break; 1314 } 1315 1316 // Otherwise, add it as a branch-through. If this isn't new 1317 // information, all the rest of the work has been done before. 1318 if (!Scope.addEHBranchThrough(Dest.getBlock())) 1319 break; 1320 } 1321 1322 Builder.ClearInsertionPoint(); 1323} 1324 1325/// All the branch fixups on the EH stack have propagated out past the 1326/// outermost normal cleanup; resolve them all by adding cases to the 1327/// given switch instruction. 1328void CodeGenFunction::ResolveAllBranchFixups(llvm::SwitchInst *Switch) { 1329 llvm::SmallPtrSet<llvm::BasicBlock*, 4> CasesAdded; 1330 1331 for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) { 1332 // Skip this fixup if its destination isn't set or if we've 1333 // already treated it. 1334 BranchFixup &Fixup = EHStack.getBranchFixup(I); 1335 if (Fixup.Destination == 0) continue; 1336 if (!CasesAdded.insert(Fixup.Destination)) continue; 1337 1338 Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), 1339 Fixup.Destination); 1340 } 1341 1342 EHStack.clearFixups(); 1343} 1344 1345void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) { 1346 assert(Block && "resolving a null target block"); 1347 if (!EHStack.getNumBranchFixups()) return; 1348 1349 assert(EHStack.hasNormalCleanups() && 1350 "branch fixups exist with no normal cleanups on stack"); 1351 1352 llvm::SmallPtrSet<llvm::BasicBlock*, 4> ModifiedOptimisticBlocks; 1353 bool ResolvedAny = false; 1354 1355 for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) { 1356 // Skip this fixup if its destination doesn't match. 1357 BranchFixup &Fixup = EHStack.getBranchFixup(I); 1358 if (Fixup.Destination != Block) continue; 1359 1360 Fixup.Destination = 0; 1361 ResolvedAny = true; 1362 1363 // If it doesn't have an optimistic branch block, LatestBranch is 1364 // already pointing to the right place. 1365 llvm::BasicBlock *BranchBB = Fixup.OptimisticBranchBlock; 1366 if (!BranchBB) 1367 continue; 1368 1369 // Don't process the same optimistic branch block twice. 1370 if (!ModifiedOptimisticBlocks.insert(BranchBB)) 1371 continue; 1372 1373 llvm::SwitchInst *Switch = TransitionToCleanupSwitch(*this, BranchBB); 1374 1375 // Add a case to the switch. 1376 Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Block); 1377 } 1378 1379 if (ResolvedAny) 1380 EHStack.popNullFixups(); 1381} 1382 1383static bool IsUsedAsNormalCleanup(EHScopeStack &EHStack, 1384 EHScopeStack::stable_iterator C) { 1385 // If we needed a normal block for any reason, that counts. 1386 if (cast<EHCleanupScope>(*EHStack.find(C)).getNormalBlock()) 1387 return true; 1388 1389 // Check whether any enclosed cleanups were needed. 1390 for (EHScopeStack::stable_iterator 1391 I = EHStack.getInnermostNormalCleanup(); 1392 I != C; ) { 1393 assert(C.strictlyEncloses(I)); 1394 EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I)); 1395 if (S.getNormalBlock()) return true; 1396 I = S.getEnclosingNormalCleanup(); 1397 } 1398 1399 return false; 1400} 1401 1402static bool IsUsedAsEHCleanup(EHScopeStack &EHStack, 1403 EHScopeStack::stable_iterator C) { 1404 // If we needed an EH block for any reason, that counts. 1405 if (cast<EHCleanupScope>(*EHStack.find(C)).getEHBlock()) 1406 return true; 1407 1408 // Check whether any enclosed cleanups were needed. 1409 for (EHScopeStack::stable_iterator 1410 I = EHStack.getInnermostEHCleanup(); I != C; ) { 1411 assert(C.strictlyEncloses(I)); 1412 EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I)); 1413 if (S.getEHBlock()) return true; 1414 I = S.getEnclosingEHCleanup(); 1415 } 1416 1417 return false; 1418} 1419 1420enum ForActivation_t { 1421 ForActivation, 1422 ForDeactivation 1423}; 1424 1425/// The given cleanup block is changing activation state. Configure a 1426/// cleanup variable if necessary. 1427/// 1428/// It would be good if we had some way of determining if there were 1429/// extra uses *after* the change-over point. 1430static void SetupCleanupBlockActivation(CodeGenFunction &CGF, 1431 EHScopeStack::stable_iterator C, 1432 ForActivation_t Kind) { 1433 EHCleanupScope &Scope = cast<EHCleanupScope>(*CGF.EHStack.find(C)); 1434 1435 // We always need the flag if we're activating the cleanup, because 1436 // we have to assume that the current location doesn't necessarily 1437 // dominate all future uses of the cleanup. 1438 bool NeedFlag = (Kind == ForActivation); 1439 1440 // Calculate whether the cleanup was used: 1441 1442 // - as a normal cleanup 1443 if (Scope.isNormalCleanup() && IsUsedAsNormalCleanup(CGF.EHStack, C)) { 1444 Scope.setTestFlagInNormalCleanup(); 1445 NeedFlag = true; 1446 } 1447 1448 // - as an EH cleanup 1449 if (Scope.isEHCleanup() && IsUsedAsEHCleanup(CGF.EHStack, C)) { 1450 Scope.setTestFlagInEHCleanup(); 1451 NeedFlag = true; 1452 } 1453 1454 // If it hasn't yet been used as either, we're done. 1455 if (!NeedFlag) return; 1456 1457 llvm::AllocaInst *Var = Scope.getActiveFlag(); 1458 if (!Var) { 1459 Var = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), "cleanup.isactive"); 1460 Scope.setActiveFlag(Var); 1461 1462 // Initialize to true or false depending on whether it was 1463 // active up to this point. 1464 CGF.InitTempAlloca(Var, CGF.Builder.getInt1(Kind == ForDeactivation)); 1465 } 1466 1467 CGF.Builder.CreateStore(CGF.Builder.getInt1(Kind == ForActivation), Var); 1468} 1469 1470/// Activate a cleanup that was created in an inactivated state. 1471void CodeGenFunction::ActivateCleanupBlock(EHScopeStack::stable_iterator C) { 1472 assert(C != EHStack.stable_end() && "activating bottom of stack?"); 1473 EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C)); 1474 assert(!Scope.isActive() && "double activation"); 1475 1476 SetupCleanupBlockActivation(*this, C, ForActivation); 1477 1478 Scope.setActive(true); 1479} 1480 1481/// Deactive a cleanup that was created in an active state. 1482void CodeGenFunction::DeactivateCleanupBlock(EHScopeStack::stable_iterator C) { 1483 assert(C != EHStack.stable_end() && "deactivating bottom of stack?"); 1484 EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C)); 1485 assert(Scope.isActive() && "double deactivation"); 1486 1487 // If it's the top of the stack, just pop it. 1488 if (C == EHStack.stable_begin()) { 1489 // If it's a normal cleanup, we need to pretend that the 1490 // fallthrough is unreachable. 1491 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP(); 1492 PopCleanupBlock(); 1493 Builder.restoreIP(SavedIP); 1494 return; 1495 } 1496 1497 // Otherwise, follow the general case. 1498 SetupCleanupBlockActivation(*this, C, ForDeactivation); 1499 1500 Scope.setActive(false); 1501} 1502 1503llvm::Value *CodeGenFunction::getNormalCleanupDestSlot() { 1504 if (!NormalCleanupDest) 1505 NormalCleanupDest = 1506 CreateTempAlloca(Builder.getInt32Ty(), "cleanup.dest.slot"); 1507 return NormalCleanupDest; 1508} 1509 1510llvm::Value *CodeGenFunction::getEHCleanupDestSlot() { 1511 if (!EHCleanupDest) 1512 EHCleanupDest = 1513 CreateTempAlloca(Builder.getInt32Ty(), "eh.cleanup.dest.slot"); 1514 return EHCleanupDest; 1515} 1516 1517void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E, 1518 llvm::ConstantInt *Init) { 1519 assert (Init && "Invalid DeclRefExpr initializer!"); 1520 if (CGDebugInfo *Dbg = getDebugInfo()) 1521 Dbg->EmitGlobalVariable(E->getDecl(), Init, Builder); 1522} 1523