CodeGenFunction.cpp revision 8b418685e9e4f02f4eb2a76e1ec063e07552b68d
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 "CGCUDARuntime.h" 17#include "CGCXXABI.h" 18#include "CGDebugInfo.h" 19#include "CGException.h" 20#include "clang/Basic/TargetInfo.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 : CodeGenTypeCache(cgm), CGM(cgm), 33 Target(CGM.getContext().getTargetInfo()), Builder(cgm.getModule().getContext()), 34 AutoreleaseResult(false), BlockInfo(0), BlockPointer(0), 35 NormalCleanupDest(0), NextCleanupDestIndex(1), FirstBlockInfo(0), 36 EHResumeBlock(0), ExceptionSlot(0), EHSelectorSlot(0), 37 DebugInfo(0), DisableDebugInfo(false), DidCallStackSave(false), 38 IndirectBranch(0), SwitchInsn(0), CaseRangeBlock(0), UnreachableBlock(0), 39 CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0), 40 OutermostConditional(0), TerminateLandingPad(0), TerminateHandler(0), 41 TrapBB(0) { 42 43 CatchUndefined = getContext().getLangOptions().CatchUndefined; 44 CGM.getCXXABI().getMangleContext().startNewFunction(); 45} 46 47CodeGenFunction::~CodeGenFunction() { 48 // If there are any unclaimed block infos, go ahead and destroy them 49 // now. This can happen if IR-gen gets clever and skips evaluating 50 // something. 51 if (FirstBlockInfo) 52 destroyBlockInfos(FirstBlockInfo); 53} 54 55 56llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) { 57 return CGM.getTypes().ConvertTypeForMem(T); 58} 59 60llvm::Type *CodeGenFunction::ConvertType(QualType T) { 61 return CGM.getTypes().ConvertType(T); 62} 63 64bool CodeGenFunction::hasAggregateLLVMType(QualType type) { 65 switch (type.getCanonicalType()->getTypeClass()) { 66#define TYPE(name, parent) 67#define ABSTRACT_TYPE(name, parent) 68#define NON_CANONICAL_TYPE(name, parent) case Type::name: 69#define DEPENDENT_TYPE(name, parent) case Type::name: 70#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(name, parent) case Type::name: 71#include "clang/AST/TypeNodes.def" 72 llvm_unreachable("non-canonical or dependent type in IR-generation"); 73 74 case Type::Builtin: 75 case Type::Pointer: 76 case Type::BlockPointer: 77 case Type::LValueReference: 78 case Type::RValueReference: 79 case Type::MemberPointer: 80 case Type::Vector: 81 case Type::ExtVector: 82 case Type::FunctionProto: 83 case Type::FunctionNoProto: 84 case Type::Enum: 85 case Type::ObjCObjectPointer: 86 return false; 87 88 // Complexes, arrays, records, and Objective-C objects. 89 case Type::Complex: 90 case Type::ConstantArray: 91 case Type::IncompleteArray: 92 case Type::VariableArray: 93 case Type::Record: 94 case Type::ObjCObject: 95 case Type::ObjCInterface: 96 return true; 97 98 // In IRGen, atomic types are just the underlying type 99 case Type::Atomic: 100 return hasAggregateLLVMType(type->getAs<AtomicType>()->getValueType()); 101 } 102 llvm_unreachable("unknown type kind!"); 103} 104 105void CodeGenFunction::EmitReturnBlock() { 106 // For cleanliness, we try to avoid emitting the return block for 107 // simple cases. 108 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 109 110 if (CurBB) { 111 assert(!CurBB->getTerminator() && "Unexpected terminated block."); 112 113 // We have a valid insert point, reuse it if it is empty or there are no 114 // explicit jumps to the return block. 115 if (CurBB->empty() || ReturnBlock.getBlock()->use_empty()) { 116 ReturnBlock.getBlock()->replaceAllUsesWith(CurBB); 117 delete ReturnBlock.getBlock(); 118 } else 119 EmitBlock(ReturnBlock.getBlock()); 120 return; 121 } 122 123 // Otherwise, if the return block is the target of a single direct 124 // branch then we can just put the code in that block instead. This 125 // cleans up functions which started with a unified return block. 126 if (ReturnBlock.getBlock()->hasOneUse()) { 127 llvm::BranchInst *BI = 128 dyn_cast<llvm::BranchInst>(*ReturnBlock.getBlock()->use_begin()); 129 if (BI && BI->isUnconditional() && 130 BI->getSuccessor(0) == ReturnBlock.getBlock()) { 131 // Reset insertion point, including debug location, and delete the branch. 132 Builder.SetCurrentDebugLocation(BI->getDebugLoc()); 133 Builder.SetInsertPoint(BI->getParent()); 134 BI->eraseFromParent(); 135 delete ReturnBlock.getBlock(); 136 return; 137 } 138 } 139 140 // FIXME: We are at an unreachable point, there is no reason to emit the block 141 // unless it has uses. However, we still need a place to put the debug 142 // region.end for now. 143 144 EmitBlock(ReturnBlock.getBlock()); 145} 146 147static void EmitIfUsed(CodeGenFunction &CGF, llvm::BasicBlock *BB) { 148 if (!BB) return; 149 if (!BB->use_empty()) 150 return CGF.CurFn->getBasicBlockList().push_back(BB); 151 delete BB; 152} 153 154void CodeGenFunction::FinishFunction(SourceLocation EndLoc) { 155 assert(BreakContinueStack.empty() && 156 "mismatched push/pop in break/continue stack!"); 157 158 // Pop any cleanups that might have been associated with the 159 // parameters. Do this in whatever block we're currently in; it's 160 // important to do this before we enter the return block or return 161 // edges will be *really* confused. 162 if (EHStack.stable_begin() != PrologueCleanupDepth) 163 PopCleanupBlocks(PrologueCleanupDepth); 164 165 // Emit function epilog (to return). 166 EmitReturnBlock(); 167 168 if (ShouldInstrumentFunction()) 169 EmitFunctionInstrumentation("__cyg_profile_func_exit"); 170 171 // Emit debug descriptor for function end. 172 if (CGDebugInfo *DI = getDebugInfo()) { 173 DI->setLocation(EndLoc); 174 DI->EmitFunctionEnd(Builder); 175 } 176 177 EmitFunctionEpilog(*CurFnInfo); 178 EmitEndEHSpec(CurCodeDecl); 179 180 assert(EHStack.empty() && 181 "did not remove all scopes from cleanup stack!"); 182 183 // If someone did an indirect goto, emit the indirect goto block at the end of 184 // the function. 185 if (IndirectBranch) { 186 EmitBlock(IndirectBranch->getParent()); 187 Builder.ClearInsertionPoint(); 188 } 189 190 // Remove the AllocaInsertPt instruction, which is just a convenience for us. 191 llvm::Instruction *Ptr = AllocaInsertPt; 192 AllocaInsertPt = 0; 193 Ptr->eraseFromParent(); 194 195 // If someone took the address of a label but never did an indirect goto, we 196 // made a zero entry PHI node, which is illegal, zap it now. 197 if (IndirectBranch) { 198 llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress()); 199 if (PN->getNumIncomingValues() == 0) { 200 PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType())); 201 PN->eraseFromParent(); 202 } 203 } 204 205 EmitIfUsed(*this, EHResumeBlock); 206 EmitIfUsed(*this, TerminateLandingPad); 207 EmitIfUsed(*this, TerminateHandler); 208 EmitIfUsed(*this, UnreachableBlock); 209 210 if (CGM.getCodeGenOpts().EmitDeclMetadata) 211 EmitDeclMetadata(); 212} 213 214/// ShouldInstrumentFunction - Return true if the current function should be 215/// instrumented with __cyg_profile_func_* calls 216bool CodeGenFunction::ShouldInstrumentFunction() { 217 if (!CGM.getCodeGenOpts().InstrumentFunctions) 218 return false; 219 if (!CurFuncDecl || CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>()) 220 return false; 221 return true; 222} 223 224/// EmitFunctionInstrumentation - Emit LLVM code to call the specified 225/// instrumentation function with the current function and the call site, if 226/// function instrumentation is enabled. 227void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) { 228 // void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site); 229 llvm::PointerType *PointerTy = Int8PtrTy; 230 llvm::Type *ProfileFuncArgs[] = { PointerTy, PointerTy }; 231 llvm::FunctionType *FunctionTy = 232 llvm::FunctionType::get(VoidTy, ProfileFuncArgs, false); 233 234 llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn); 235 llvm::CallInst *CallSite = Builder.CreateCall( 236 CGM.getIntrinsic(llvm::Intrinsic::returnaddress), 237 llvm::ConstantInt::get(Int32Ty, 0), 238 "callsite"); 239 240 Builder.CreateCall2(F, 241 llvm::ConstantExpr::getBitCast(CurFn, PointerTy), 242 CallSite); 243} 244 245void CodeGenFunction::EmitMCountInstrumentation() { 246 llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false); 247 248 llvm::Constant *MCountFn = CGM.CreateRuntimeFunction(FTy, 249 Target.getMCountName()); 250 Builder.CreateCall(MCountFn); 251} 252 253void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy, 254 llvm::Function *Fn, 255 const CGFunctionInfo &FnInfo, 256 const FunctionArgList &Args, 257 SourceLocation StartLoc) { 258 const Decl *D = GD.getDecl(); 259 260 DidCallStackSave = false; 261 CurCodeDecl = CurFuncDecl = D; 262 FnRetTy = RetTy; 263 CurFn = Fn; 264 CurFnInfo = &FnInfo; 265 assert(CurFn->isDeclaration() && "Function already has body?"); 266 267 // Pass inline keyword to optimizer if it appears explicitly on any 268 // declaration. 269 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) 270 for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(), 271 RE = FD->redecls_end(); RI != RE; ++RI) 272 if (RI->isInlineSpecified()) { 273 Fn->addFnAttr(llvm::Attribute::InlineHint); 274 break; 275 } 276 277 if (getContext().getLangOptions().OpenCL) { 278 // Add metadata for a kernel function. 279 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) 280 if (FD->hasAttr<OpenCLKernelAttr>()) { 281 llvm::LLVMContext &Context = getLLVMContext(); 282 llvm::NamedMDNode *OpenCLMetadata = 283 CGM.getModule().getOrInsertNamedMetadata("opencl.kernels"); 284 285 llvm::Value *Op = Fn; 286 OpenCLMetadata->addOperand(llvm::MDNode::get(Context, Op)); 287 } 288 } 289 290 llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn); 291 292 // Create a marker to make it easy to insert allocas into the entryblock 293 // later. Don't create this with the builder, because we don't want it 294 // folded. 295 llvm::Value *Undef = llvm::UndefValue::get(Int32Ty); 296 AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB); 297 if (Builder.isNamePreserving()) 298 AllocaInsertPt->setName("allocapt"); 299 300 ReturnBlock = getJumpDestInCurrentScope("return"); 301 302 Builder.SetInsertPoint(EntryBB); 303 304 // Emit subprogram debug descriptor. 305 if (CGDebugInfo *DI = getDebugInfo()) { 306 unsigned NumArgs = 0; 307 QualType *ArgsArray = new QualType[Args.size()]; 308 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); 309 i != e; ++i) { 310 ArgsArray[NumArgs++] = (*i)->getType(); 311 } 312 313 QualType FnType = 314 getContext().getFunctionType(RetTy, ArgsArray, NumArgs, 315 FunctionProtoType::ExtProtoInfo()); 316 317 delete[] ArgsArray; 318 319 DI->setLocation(StartLoc); 320 DI->EmitFunctionStart(GD, FnType, CurFn, Builder); 321 } 322 323 if (ShouldInstrumentFunction()) 324 EmitFunctionInstrumentation("__cyg_profile_func_enter"); 325 326 if (CGM.getCodeGenOpts().InstrumentForProfiling) 327 EmitMCountInstrumentation(); 328 329 if (RetTy->isVoidType()) { 330 // Void type; nothing to return. 331 ReturnValue = 0; 332 } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect && 333 hasAggregateLLVMType(CurFnInfo->getReturnType())) { 334 // Indirect aggregate return; emit returned value directly into sret slot. 335 // This reduces code size, and affects correctness in C++. 336 ReturnValue = CurFn->arg_begin(); 337 } else { 338 ReturnValue = CreateIRTemp(RetTy, "retval"); 339 340 // Tell the epilog emitter to autorelease the result. We do this 341 // now so that various specialized functions can suppress it 342 // during their IR-generation. 343 if (getLangOptions().ObjCAutoRefCount && 344 !CurFnInfo->isReturnsRetained() && 345 RetTy->isObjCRetainableType()) 346 AutoreleaseResult = true; 347 } 348 349 EmitStartEHSpec(CurCodeDecl); 350 351 PrologueCleanupDepth = EHStack.stable_begin(); 352 EmitFunctionProlog(*CurFnInfo, CurFn, Args); 353 354 if (D && isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance()) 355 CGM.getCXXABI().EmitInstanceFunctionProlog(*this); 356 357 // If any of the arguments have a variably modified type, make sure to 358 // emit the type size. 359 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); 360 i != e; ++i) { 361 QualType Ty = (*i)->getType(); 362 363 if (Ty->isVariablyModifiedType()) 364 EmitVariablyModifiedType(Ty); 365 } 366 // Emit a location at the end of the prologue. 367 if (CGDebugInfo *DI = getDebugInfo()) 368 DI->EmitLocation(Builder, StartLoc); 369} 370 371void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) { 372 const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl()); 373 assert(FD->getBody()); 374 EmitStmt(FD->getBody()); 375} 376 377/// Tries to mark the given function nounwind based on the 378/// non-existence of any throwing calls within it. We believe this is 379/// lightweight enough to do at -O0. 380static void TryMarkNoThrow(llvm::Function *F) { 381 // LLVM treats 'nounwind' on a function as part of the type, so we 382 // can't do this on functions that can be overwritten. 383 if (F->mayBeOverridden()) return; 384 385 for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI) 386 for (llvm::BasicBlock::iterator 387 BI = FI->begin(), BE = FI->end(); BI != BE; ++BI) 388 if (llvm::CallInst *Call = dyn_cast<llvm::CallInst>(&*BI)) { 389 if (!Call->doesNotThrow()) 390 return; 391 } else if (isa<llvm::ResumeInst>(&*BI)) { 392 return; 393 } 394 F->setDoesNotThrow(true); 395} 396 397void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn, 398 const CGFunctionInfo &FnInfo) { 399 const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl()); 400 401 // Check if we should generate debug info for this function. 402 if (CGM.getModuleDebugInfo() && !FD->hasAttr<NoDebugAttr>()) 403 DebugInfo = CGM.getModuleDebugInfo(); 404 405 FunctionArgList Args; 406 QualType ResTy = FD->getResultType(); 407 408 CurGD = GD; 409 if (isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isInstance()) 410 CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args); 411 412 if (FD->getNumParams()) 413 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) 414 Args.push_back(FD->getParamDecl(i)); 415 416 SourceRange BodyRange; 417 if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange(); 418 419 // Emit the standard function prologue. 420 StartFunction(GD, ResTy, Fn, FnInfo, Args, BodyRange.getBegin()); 421 422 // Generate the body of the function. 423 if (isa<CXXDestructorDecl>(FD)) 424 EmitDestructorBody(Args); 425 else if (isa<CXXConstructorDecl>(FD)) 426 EmitConstructorBody(Args); 427 else if (getContext().getLangOptions().CUDA && 428 !CGM.getCodeGenOpts().CUDAIsDevice && 429 FD->hasAttr<CUDAGlobalAttr>()) 430 CGM.getCUDARuntime().EmitDeviceStubBody(*this, Args); 431 else 432 EmitFunctionBody(Args); 433 434 // Emit the standard function epilogue. 435 FinishFunction(BodyRange.getEnd()); 436 437 // If we haven't marked the function nothrow through other means, do 438 // a quick pass now to see if we can. 439 if (!CurFn->doesNotThrow()) 440 TryMarkNoThrow(CurFn); 441} 442 443/// ContainsLabel - Return true if the statement contains a label in it. If 444/// this statement is not executed normally, it not containing a label means 445/// that we can just remove the code. 446bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { 447 // Null statement, not a label! 448 if (S == 0) return false; 449 450 // If this is a label, we have to emit the code, consider something like: 451 // if (0) { ... foo: bar(); } goto foo; 452 // 453 // TODO: If anyone cared, we could track __label__'s, since we know that you 454 // can't jump to one from outside their declared region. 455 if (isa<LabelStmt>(S)) 456 return true; 457 458 // If this is a case/default statement, and we haven't seen a switch, we have 459 // to emit the code. 460 if (isa<SwitchCase>(S) && !IgnoreCaseStmts) 461 return true; 462 463 // If this is a switch statement, we want to ignore cases below it. 464 if (isa<SwitchStmt>(S)) 465 IgnoreCaseStmts = true; 466 467 // Scan subexpressions for verboten labels. 468 for (Stmt::const_child_range I = S->children(); I; ++I) 469 if (ContainsLabel(*I, IgnoreCaseStmts)) 470 return true; 471 472 return false; 473} 474 475/// containsBreak - Return true if the statement contains a break out of it. 476/// If the statement (recursively) contains a switch or loop with a break 477/// inside of it, this is fine. 478bool CodeGenFunction::containsBreak(const Stmt *S) { 479 // Null statement, not a label! 480 if (S == 0) return false; 481 482 // If this is a switch or loop that defines its own break scope, then we can 483 // include it and anything inside of it. 484 if (isa<SwitchStmt>(S) || isa<WhileStmt>(S) || isa<DoStmt>(S) || 485 isa<ForStmt>(S)) 486 return false; 487 488 if (isa<BreakStmt>(S)) 489 return true; 490 491 // Scan subexpressions for verboten breaks. 492 for (Stmt::const_child_range I = S->children(); I; ++I) 493 if (containsBreak(*I)) 494 return true; 495 496 return false; 497} 498 499 500/// ConstantFoldsToSimpleInteger - If the specified expression does not fold 501/// to a constant, or if it does but contains a label, return false. If it 502/// constant folds return true and set the boolean result in Result. 503bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond, 504 bool &ResultBool) { 505 llvm::APInt ResultInt; 506 if (!ConstantFoldsToSimpleInteger(Cond, ResultInt)) 507 return false; 508 509 ResultBool = ResultInt.getBoolValue(); 510 return true; 511} 512 513/// ConstantFoldsToSimpleInteger - If the specified expression does not fold 514/// to a constant, or if it does but contains a label, return false. If it 515/// constant folds return true and set the folded value. 516bool CodeGenFunction:: 517ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APInt &ResultInt) { 518 // FIXME: Rename and handle conversion of other evaluatable things 519 // to bool. 520 llvm::APSInt Int; 521 if (!Cond->EvaluateAsInt(Int, getContext())) 522 return false; // Not foldable, not integer or not fully evaluatable. 523 524 if (CodeGenFunction::ContainsLabel(Cond)) 525 return false; // Contains a label. 526 527 ResultInt = Int; 528 return true; 529} 530 531 532 533/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if 534/// statement) to the specified blocks. Based on the condition, this might try 535/// to simplify the codegen of the conditional based on the branch. 536/// 537void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, 538 llvm::BasicBlock *TrueBlock, 539 llvm::BasicBlock *FalseBlock) { 540 Cond = Cond->IgnoreParens(); 541 542 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { 543 // Handle X && Y in a condition. 544 if (CondBOp->getOpcode() == BO_LAnd) { 545 // If we have "1 && X", simplify the code. "0 && X" would have constant 546 // folded if the case was simple enough. 547 bool ConstantBool = false; 548 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) && 549 ConstantBool) { 550 // br(1 && X) -> br(X). 551 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 552 } 553 554 // If we have "X && 1", simplify the code to use an uncond branch. 555 // "X && 0" would have been constant folded to 0. 556 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) && 557 ConstantBool) { 558 // br(X && 1) -> br(X). 559 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 560 } 561 562 // Emit the LHS as a conditional. If the LHS conditional is false, we 563 // want to jump to the FalseBlock. 564 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); 565 566 ConditionalEvaluation eval(*this); 567 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); 568 EmitBlock(LHSTrue); 569 570 // Any temporaries created here are conditional. 571 eval.begin(*this); 572 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 573 eval.end(*this); 574 575 return; 576 } 577 578 if (CondBOp->getOpcode() == BO_LOr) { 579 // If we have "0 || X", simplify the code. "1 || X" would have constant 580 // folded if the case was simple enough. 581 bool ConstantBool = false; 582 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) && 583 !ConstantBool) { 584 // br(0 || X) -> br(X). 585 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 586 } 587 588 // If we have "X || 0", simplify the code to use an uncond branch. 589 // "X || 1" would have been constant folded to 1. 590 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) && 591 !ConstantBool) { 592 // br(X || 0) -> br(X). 593 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 594 } 595 596 // Emit the LHS as a conditional. If the LHS conditional is true, we 597 // want to jump to the TrueBlock. 598 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); 599 600 ConditionalEvaluation eval(*this); 601 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); 602 EmitBlock(LHSFalse); 603 604 // Any temporaries created here are conditional. 605 eval.begin(*this); 606 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 607 eval.end(*this); 608 609 return; 610 } 611 } 612 613 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { 614 // br(!x, t, f) -> br(x, f, t) 615 if (CondUOp->getOpcode() == UO_LNot) 616 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); 617 } 618 619 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) { 620 // Handle ?: operator. 621 622 // Just ignore GNU ?: extension. 623 if (CondOp->getLHS()) { 624 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) 625 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); 626 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); 627 628 ConditionalEvaluation cond(*this); 629 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); 630 631 cond.begin(*this); 632 EmitBlock(LHSBlock); 633 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); 634 cond.end(*this); 635 636 cond.begin(*this); 637 EmitBlock(RHSBlock); 638 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); 639 cond.end(*this); 640 641 return; 642 } 643 } 644 645 // Emit the code with the fully general case. 646 llvm::Value *CondV = EvaluateExprAsBool(Cond); 647 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); 648} 649 650/// ErrorUnsupported - Print out an error that codegen doesn't support the 651/// specified stmt yet. 652void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, 653 bool OmitOnError) { 654 CGM.ErrorUnsupported(S, Type, OmitOnError); 655} 656 657/// emitNonZeroVLAInit - Emit the "zero" initialization of a 658/// variable-length array whose elements have a non-zero bit-pattern. 659/// 660/// \param src - a char* pointing to the bit-pattern for a single 661/// base element of the array 662/// \param sizeInChars - the total size of the VLA, in chars 663/// \param align - the total alignment of the VLA 664static void emitNonZeroVLAInit(CodeGenFunction &CGF, QualType baseType, 665 llvm::Value *dest, llvm::Value *src, 666 llvm::Value *sizeInChars) { 667 std::pair<CharUnits,CharUnits> baseSizeAndAlign 668 = CGF.getContext().getTypeInfoInChars(baseType); 669 670 CGBuilderTy &Builder = CGF.Builder; 671 672 llvm::Value *baseSizeInChars 673 = llvm::ConstantInt::get(CGF.IntPtrTy, baseSizeAndAlign.first.getQuantity()); 674 675 llvm::Type *i8p = Builder.getInt8PtrTy(); 676 677 llvm::Value *begin = Builder.CreateBitCast(dest, i8p, "vla.begin"); 678 llvm::Value *end = Builder.CreateInBoundsGEP(dest, sizeInChars, "vla.end"); 679 680 llvm::BasicBlock *originBB = CGF.Builder.GetInsertBlock(); 681 llvm::BasicBlock *loopBB = CGF.createBasicBlock("vla-init.loop"); 682 llvm::BasicBlock *contBB = CGF.createBasicBlock("vla-init.cont"); 683 684 // Make a loop over the VLA. C99 guarantees that the VLA element 685 // count must be nonzero. 686 CGF.EmitBlock(loopBB); 687 688 llvm::PHINode *cur = Builder.CreatePHI(i8p, 2, "vla.cur"); 689 cur->addIncoming(begin, originBB); 690 691 // memcpy the individual element bit-pattern. 692 Builder.CreateMemCpy(cur, src, baseSizeInChars, 693 baseSizeAndAlign.second.getQuantity(), 694 /*volatile*/ false); 695 696 // Go to the next element. 697 llvm::Value *next = Builder.CreateConstInBoundsGEP1_32(cur, 1, "vla.next"); 698 699 // Leave if that's the end of the VLA. 700 llvm::Value *done = Builder.CreateICmpEQ(next, end, "vla-init.isdone"); 701 Builder.CreateCondBr(done, contBB, loopBB); 702 cur->addIncoming(next, loopBB); 703 704 CGF.EmitBlock(contBB); 705} 706 707void 708CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) { 709 // Ignore empty classes in C++. 710 if (getContext().getLangOptions().CPlusPlus) { 711 if (const RecordType *RT = Ty->getAs<RecordType>()) { 712 if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty()) 713 return; 714 } 715 } 716 717 // Cast the dest ptr to the appropriate i8 pointer type. 718 unsigned DestAS = 719 cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace(); 720 llvm::Type *BP = Builder.getInt8PtrTy(DestAS); 721 if (DestPtr->getType() != BP) 722 DestPtr = Builder.CreateBitCast(DestPtr, BP); 723 724 // Get size and alignment info for this aggregate. 725 std::pair<CharUnits, CharUnits> TypeInfo = 726 getContext().getTypeInfoInChars(Ty); 727 CharUnits Size = TypeInfo.first; 728 CharUnits Align = TypeInfo.second; 729 730 llvm::Value *SizeVal; 731 const VariableArrayType *vla; 732 733 // Don't bother emitting a zero-byte memset. 734 if (Size.isZero()) { 735 // But note that getTypeInfo returns 0 for a VLA. 736 if (const VariableArrayType *vlaType = 737 dyn_cast_or_null<VariableArrayType>( 738 getContext().getAsArrayType(Ty))) { 739 QualType eltType; 740 llvm::Value *numElts; 741 llvm::tie(numElts, eltType) = getVLASize(vlaType); 742 743 SizeVal = numElts; 744 CharUnits eltSize = getContext().getTypeSizeInChars(eltType); 745 if (!eltSize.isOne()) 746 SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(eltSize)); 747 vla = vlaType; 748 } else { 749 return; 750 } 751 } else { 752 SizeVal = CGM.getSize(Size); 753 vla = 0; 754 } 755 756 // If the type contains a pointer to data member we can't memset it to zero. 757 // Instead, create a null constant and copy it to the destination. 758 // TODO: there are other patterns besides zero that we can usefully memset, 759 // like -1, which happens to be the pattern used by member-pointers. 760 if (!CGM.getTypes().isZeroInitializable(Ty)) { 761 // For a VLA, emit a single element, then splat that over the VLA. 762 if (vla) Ty = getContext().getBaseElementType(vla); 763 764 llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty); 765 766 llvm::GlobalVariable *NullVariable = 767 new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(), 768 /*isConstant=*/true, 769 llvm::GlobalVariable::PrivateLinkage, 770 NullConstant, Twine()); 771 llvm::Value *SrcPtr = 772 Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy()); 773 774 if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal); 775 776 // Get and call the appropriate llvm.memcpy overload. 777 Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align.getQuantity(), false); 778 return; 779 } 780 781 // Otherwise, just memset the whole thing to zero. This is legal 782 // because in LLVM, all default initializers (other than the ones we just 783 // handled above) are guaranteed to have a bit pattern of all zeros. 784 Builder.CreateMemSet(DestPtr, Builder.getInt8(0), SizeVal, 785 Align.getQuantity(), false); 786} 787 788llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *L) { 789 // Make sure that there is a block for the indirect goto. 790 if (IndirectBranch == 0) 791 GetIndirectGotoBlock(); 792 793 llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock(); 794 795 // Make sure the indirect branch includes all of the address-taken blocks. 796 IndirectBranch->addDestination(BB); 797 return llvm::BlockAddress::get(CurFn, BB); 798} 799 800llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() { 801 // If we already made the indirect branch for indirect goto, return its block. 802 if (IndirectBranch) return IndirectBranch->getParent(); 803 804 CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto")); 805 806 // Create the PHI node that indirect gotos will add entries to. 807 llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, 0, 808 "indirect.goto.dest"); 809 810 // Create the indirect branch instruction. 811 IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal); 812 return IndirectBranch->getParent(); 813} 814 815/// Computes the length of an array in elements, as well as the base 816/// element type and a properly-typed first element pointer. 817llvm::Value *CodeGenFunction::emitArrayLength(const ArrayType *origArrayType, 818 QualType &baseType, 819 llvm::Value *&addr) { 820 const ArrayType *arrayType = origArrayType; 821 822 // If it's a VLA, we have to load the stored size. Note that 823 // this is the size of the VLA in bytes, not its size in elements. 824 llvm::Value *numVLAElements = 0; 825 if (isa<VariableArrayType>(arrayType)) { 826 numVLAElements = getVLASize(cast<VariableArrayType>(arrayType)).first; 827 828 // Walk into all VLAs. This doesn't require changes to addr, 829 // which has type T* where T is the first non-VLA element type. 830 do { 831 QualType elementType = arrayType->getElementType(); 832 arrayType = getContext().getAsArrayType(elementType); 833 834 // If we only have VLA components, 'addr' requires no adjustment. 835 if (!arrayType) { 836 baseType = elementType; 837 return numVLAElements; 838 } 839 } while (isa<VariableArrayType>(arrayType)); 840 841 // We get out here only if we find a constant array type 842 // inside the VLA. 843 } 844 845 // We have some number of constant-length arrays, so addr should 846 // have LLVM type [M x [N x [...]]]*. Build a GEP that walks 847 // down to the first element of addr. 848 SmallVector<llvm::Value*, 8> gepIndices; 849 850 // GEP down to the array type. 851 llvm::ConstantInt *zero = Builder.getInt32(0); 852 gepIndices.push_back(zero); 853 854 // It's more efficient to calculate the count from the LLVM 855 // constant-length arrays than to re-evaluate the array bounds. 856 uint64_t countFromCLAs = 1; 857 858 llvm::ArrayType *llvmArrayType = 859 cast<llvm::ArrayType>( 860 cast<llvm::PointerType>(addr->getType())->getElementType()); 861 while (true) { 862 assert(isa<ConstantArrayType>(arrayType)); 863 assert(cast<ConstantArrayType>(arrayType)->getSize().getZExtValue() 864 == llvmArrayType->getNumElements()); 865 866 gepIndices.push_back(zero); 867 countFromCLAs *= llvmArrayType->getNumElements(); 868 869 llvmArrayType = 870 dyn_cast<llvm::ArrayType>(llvmArrayType->getElementType()); 871 if (!llvmArrayType) break; 872 873 arrayType = getContext().getAsArrayType(arrayType->getElementType()); 874 assert(arrayType && "LLVM and Clang types are out-of-synch"); 875 } 876 877 baseType = arrayType->getElementType(); 878 879 // Create the actual GEP. 880 addr = Builder.CreateInBoundsGEP(addr, gepIndices, "array.begin"); 881 882 llvm::Value *numElements 883 = llvm::ConstantInt::get(SizeTy, countFromCLAs); 884 885 // If we had any VLA dimensions, factor them in. 886 if (numVLAElements) 887 numElements = Builder.CreateNUWMul(numVLAElements, numElements); 888 889 return numElements; 890} 891 892std::pair<llvm::Value*, QualType> 893CodeGenFunction::getVLASize(QualType type) { 894 const VariableArrayType *vla = getContext().getAsVariableArrayType(type); 895 assert(vla && "type was not a variable array type!"); 896 return getVLASize(vla); 897} 898 899std::pair<llvm::Value*, QualType> 900CodeGenFunction::getVLASize(const VariableArrayType *type) { 901 // The number of elements so far; always size_t. 902 llvm::Value *numElements = 0; 903 904 QualType elementType; 905 do { 906 elementType = type->getElementType(); 907 llvm::Value *vlaSize = VLASizeMap[type->getSizeExpr()]; 908 assert(vlaSize && "no size for VLA!"); 909 assert(vlaSize->getType() == SizeTy); 910 911 if (!numElements) { 912 numElements = vlaSize; 913 } else { 914 // It's undefined behavior if this wraps around, so mark it that way. 915 numElements = Builder.CreateNUWMul(numElements, vlaSize); 916 } 917 } while ((type = getContext().getAsVariableArrayType(elementType))); 918 919 return std::pair<llvm::Value*,QualType>(numElements, elementType); 920} 921 922void CodeGenFunction::EmitVariablyModifiedType(QualType type) { 923 assert(type->isVariablyModifiedType() && 924 "Must pass variably modified type to EmitVLASizes!"); 925 926 EnsureInsertPoint(); 927 928 // We're going to walk down into the type and look for VLA 929 // expressions. 930 do { 931 assert(type->isVariablyModifiedType()); 932 933 const Type *ty = type.getTypePtr(); 934 switch (ty->getTypeClass()) { 935 936#define TYPE(Class, Base) 937#define ABSTRACT_TYPE(Class, Base) 938#define NON_CANONICAL_TYPE(Class, Base) 939#define DEPENDENT_TYPE(Class, Base) case Type::Class: 940#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) 941#include "clang/AST/TypeNodes.def" 942 llvm_unreachable("unexpected dependent type!"); 943 944 // These types are never variably-modified. 945 case Type::Builtin: 946 case Type::Complex: 947 case Type::Vector: 948 case Type::ExtVector: 949 case Type::Record: 950 case Type::Enum: 951 case Type::Elaborated: 952 case Type::TemplateSpecialization: 953 case Type::ObjCObject: 954 case Type::ObjCInterface: 955 case Type::ObjCObjectPointer: 956 llvm_unreachable("type class is never variably-modified!"); 957 958 case Type::Pointer: 959 type = cast<PointerType>(ty)->getPointeeType(); 960 break; 961 962 case Type::BlockPointer: 963 type = cast<BlockPointerType>(ty)->getPointeeType(); 964 break; 965 966 case Type::LValueReference: 967 case Type::RValueReference: 968 type = cast<ReferenceType>(ty)->getPointeeType(); 969 break; 970 971 case Type::MemberPointer: 972 type = cast<MemberPointerType>(ty)->getPointeeType(); 973 break; 974 975 case Type::ConstantArray: 976 case Type::IncompleteArray: 977 // Losing element qualification here is fine. 978 type = cast<ArrayType>(ty)->getElementType(); 979 break; 980 981 case Type::VariableArray: { 982 // Losing element qualification here is fine. 983 const VariableArrayType *vat = cast<VariableArrayType>(ty); 984 985 // Unknown size indication requires no size computation. 986 // Otherwise, evaluate and record it. 987 if (const Expr *size = vat->getSizeExpr()) { 988 // It's possible that we might have emitted this already, 989 // e.g. with a typedef and a pointer to it. 990 llvm::Value *&entry = VLASizeMap[size]; 991 if (!entry) { 992 // Always zexting here would be wrong if it weren't 993 // undefined behavior to have a negative bound. 994 entry = Builder.CreateIntCast(EmitScalarExpr(size), SizeTy, 995 /*signed*/ false); 996 } 997 } 998 type = vat->getElementType(); 999 break; 1000 } 1001 1002 case Type::FunctionProto: 1003 case Type::FunctionNoProto: 1004 type = cast<FunctionType>(ty)->getResultType(); 1005 break; 1006 1007 case Type::Paren: 1008 case Type::TypeOf: 1009 case Type::UnaryTransform: 1010 case Type::Attributed: 1011 case Type::SubstTemplateTypeParm: 1012 // Keep walking after single level desugaring. 1013 type = type.getSingleStepDesugaredType(getContext()); 1014 break; 1015 1016 case Type::Typedef: 1017 case Type::Decltype: 1018 case Type::Auto: 1019 // Stop walking: nothing to do. 1020 return; 1021 1022 case Type::TypeOfExpr: 1023 // Stop walking: emit typeof expression. 1024 EmitIgnoredExpr(cast<TypeOfExprType>(ty)->getUnderlyingExpr()); 1025 return; 1026 1027 case Type::Atomic: 1028 type = cast<AtomicType>(ty)->getValueType(); 1029 break; 1030 } 1031 } while (type->isVariablyModifiedType()); 1032} 1033 1034llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { 1035 if (getContext().getBuiltinVaListType()->isArrayType()) 1036 return EmitScalarExpr(E); 1037 return EmitLValue(E).getAddress(); 1038} 1039 1040void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E, 1041 llvm::Constant *Init) { 1042 assert (Init && "Invalid DeclRefExpr initializer!"); 1043 if (CGDebugInfo *Dbg = getDebugInfo()) 1044 Dbg->EmitGlobalVariable(E->getDecl(), Init); 1045} 1046 1047CodeGenFunction::PeepholeProtection 1048CodeGenFunction::protectFromPeepholes(RValue rvalue) { 1049 // At the moment, the only aggressive peephole we do in IR gen 1050 // is trunc(zext) folding, but if we add more, we can easily 1051 // extend this protection. 1052 1053 if (!rvalue.isScalar()) return PeepholeProtection(); 1054 llvm::Value *value = rvalue.getScalarVal(); 1055 if (!isa<llvm::ZExtInst>(value)) return PeepholeProtection(); 1056 1057 // Just make an extra bitcast. 1058 assert(HaveInsertPoint()); 1059 llvm::Instruction *inst = new llvm::BitCastInst(value, value->getType(), "", 1060 Builder.GetInsertBlock()); 1061 1062 PeepholeProtection protection; 1063 protection.Inst = inst; 1064 return protection; 1065} 1066 1067void CodeGenFunction::unprotectFromPeepholes(PeepholeProtection protection) { 1068 if (!protection.Inst) return; 1069 1070 // In theory, we could try to duplicate the peepholes now, but whatever. 1071 protection.Inst->eraseFromParent(); 1072} 1073 1074llvm::Value *CodeGenFunction::EmitAnnotationCall(llvm::Value *AnnotationFn, 1075 llvm::Value *AnnotatedVal, 1076 llvm::StringRef AnnotationStr, 1077 SourceLocation Location) { 1078 llvm::Value *Args[4] = { 1079 AnnotatedVal, 1080 Builder.CreateBitCast(CGM.EmitAnnotationString(AnnotationStr), Int8PtrTy), 1081 Builder.CreateBitCast(CGM.EmitAnnotationUnit(Location), Int8PtrTy), 1082 CGM.EmitAnnotationLineNo(Location) 1083 }; 1084 return Builder.CreateCall(AnnotationFn, Args); 1085} 1086 1087void CodeGenFunction::EmitVarAnnotations(const VarDecl *D, llvm::Value *V) { 1088 assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute"); 1089 // FIXME We create a new bitcast for every annotation because that's what 1090 // llvm-gcc was doing. 1091 for (specific_attr_iterator<AnnotateAttr> 1092 ai = D->specific_attr_begin<AnnotateAttr>(), 1093 ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai) 1094 EmitAnnotationCall(CGM.getIntrinsic(llvm::Intrinsic::var_annotation), 1095 Builder.CreateBitCast(V, CGM.Int8PtrTy, V->getName()), 1096 (*ai)->getAnnotation(), D->getLocation()); 1097} 1098 1099llvm::Value *CodeGenFunction::EmitFieldAnnotations(const FieldDecl *D, 1100 llvm::Value *V) { 1101 assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute"); 1102 llvm::Type *VTy = V->getType(); 1103 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::ptr_annotation, 1104 CGM.Int8PtrTy); 1105 1106 for (specific_attr_iterator<AnnotateAttr> 1107 ai = D->specific_attr_begin<AnnotateAttr>(), 1108 ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai) { 1109 // FIXME Always emit the cast inst so we can differentiate between 1110 // annotation on the first field of a struct and annotation on the struct 1111 // itself. 1112 if (VTy != CGM.Int8PtrTy) 1113 V = Builder.Insert(new llvm::BitCastInst(V, CGM.Int8PtrTy)); 1114 V = EmitAnnotationCall(F, V, (*ai)->getAnnotation(), D->getLocation()); 1115 V = Builder.CreateBitCast(V, VTy); 1116 } 1117 1118 return V; 1119} 1120