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/APValue.h" 22 #include "clang/AST/ASTContext.h" 23 #include "clang/AST/Decl.h" 24 #include "clang/AST/DeclCXX.h" 25 #include "clang/AST/StmtCXX.h" 26 #include "clang/Frontend/CodeGenOptions.h" 27 #include "llvm/Target/TargetData.h" 28 #include "llvm/Intrinsics.h" 29 using namespace clang; 30 using namespace CodeGen; 31 32 CodeGenFunction::CodeGenFunction(CodeGenModule &cgm) 33 : CodeGenTypeCache(cgm), CGM(cgm), 34 Target(CGM.getContext().getTargetInfo()), Builder(cgm.getModule().getContext()), 35 AutoreleaseResult(false), BlockInfo(0), BlockPointer(0), 36 NormalCleanupDest(0), NextCleanupDestIndex(1), 37 EHResumeBlock(0), ExceptionSlot(0), EHSelectorSlot(0), 38 DebugInfo(0), DisableDebugInfo(false), DidCallStackSave(false), 39 IndirectBranch(0), SwitchInsn(0), CaseRangeBlock(0), UnreachableBlock(0), 40 CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0), 41 OutermostConditional(0), TerminateLandingPad(0), TerminateHandler(0), 42 TrapBB(0) { 43 44 CatchUndefined = getContext().getLangOptions().CatchUndefined; 45 CGM.getCXXABI().getMangleContext().startNewFunction(); 46 } 47 48 49 llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) { 50 return CGM.getTypes().ConvertTypeForMem(T); 51 } 52 53 llvm::Type *CodeGenFunction::ConvertType(QualType T) { 54 return CGM.getTypes().ConvertType(T); 55 } 56 57 bool CodeGenFunction::hasAggregateLLVMType(QualType type) { 58 switch (type.getCanonicalType()->getTypeClass()) { 59 #define TYPE(name, parent) 60 #define ABSTRACT_TYPE(name, parent) 61 #define NON_CANONICAL_TYPE(name, parent) case Type::name: 62 #define DEPENDENT_TYPE(name, parent) case Type::name: 63 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(name, parent) case Type::name: 64 #include "clang/AST/TypeNodes.def" 65 llvm_unreachable("non-canonical or dependent type in IR-generation"); 66 67 case Type::Builtin: 68 case Type::Pointer: 69 case Type::BlockPointer: 70 case Type::LValueReference: 71 case Type::RValueReference: 72 case Type::MemberPointer: 73 case Type::Vector: 74 case Type::ExtVector: 75 case Type::FunctionProto: 76 case Type::FunctionNoProto: 77 case Type::Enum: 78 case Type::ObjCObjectPointer: 79 return false; 80 81 // Complexes, arrays, records, and Objective-C objects. 82 case Type::Complex: 83 case Type::ConstantArray: 84 case Type::IncompleteArray: 85 case Type::VariableArray: 86 case Type::Record: 87 case Type::ObjCObject: 88 case Type::ObjCInterface: 89 return true; 90 91 // In IRGen, atomic types are just the underlying type 92 case Type::Atomic: 93 return hasAggregateLLVMType(type->getAs<AtomicType>()->getValueType()); 94 } 95 llvm_unreachable("unknown type kind!"); 96 } 97 98 void CodeGenFunction::EmitReturnBlock() { 99 // For cleanliness, we try to avoid emitting the return block for 100 // simple cases. 101 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 102 103 if (CurBB) { 104 assert(!CurBB->getTerminator() && "Unexpected terminated block."); 105 106 // We have a valid insert point, reuse it if it is empty or there are no 107 // explicit jumps to the return block. 108 if (CurBB->empty() || ReturnBlock.getBlock()->use_empty()) { 109 ReturnBlock.getBlock()->replaceAllUsesWith(CurBB); 110 delete ReturnBlock.getBlock(); 111 } else 112 EmitBlock(ReturnBlock.getBlock()); 113 return; 114 } 115 116 // Otherwise, if the return block is the target of a single direct 117 // branch then we can just put the code in that block instead. This 118 // cleans up functions which started with a unified return block. 119 if (ReturnBlock.getBlock()->hasOneUse()) { 120 llvm::BranchInst *BI = 121 dyn_cast<llvm::BranchInst>(*ReturnBlock.getBlock()->use_begin()); 122 if (BI && BI->isUnconditional() && 123 BI->getSuccessor(0) == ReturnBlock.getBlock()) { 124 // Reset insertion point, including debug location, and delete the branch. 125 Builder.SetCurrentDebugLocation(BI->getDebugLoc()); 126 Builder.SetInsertPoint(BI->getParent()); 127 BI->eraseFromParent(); 128 delete ReturnBlock.getBlock(); 129 return; 130 } 131 } 132 133 // FIXME: We are at an unreachable point, there is no reason to emit the block 134 // unless it has uses. However, we still need a place to put the debug 135 // region.end for now. 136 137 EmitBlock(ReturnBlock.getBlock()); 138 } 139 140 static void EmitIfUsed(CodeGenFunction &CGF, llvm::BasicBlock *BB) { 141 if (!BB) return; 142 if (!BB->use_empty()) 143 return CGF.CurFn->getBasicBlockList().push_back(BB); 144 delete BB; 145 } 146 147 void CodeGenFunction::FinishFunction(SourceLocation EndLoc) { 148 assert(BreakContinueStack.empty() && 149 "mismatched push/pop in break/continue stack!"); 150 151 // Pop any cleanups that might have been associated with the 152 // parameters. Do this in whatever block we're currently in; it's 153 // important to do this before we enter the return block or return 154 // edges will be *really* confused. 155 if (EHStack.stable_begin() != PrologueCleanupDepth) 156 PopCleanupBlocks(PrologueCleanupDepth); 157 158 // Emit function epilog (to return). 159 EmitReturnBlock(); 160 161 if (ShouldInstrumentFunction()) 162 EmitFunctionInstrumentation("__cyg_profile_func_exit"); 163 164 // Emit debug descriptor for function end. 165 if (CGDebugInfo *DI = getDebugInfo()) { 166 DI->setLocation(EndLoc); 167 DI->EmitFunctionEnd(Builder); 168 } 169 170 EmitFunctionEpilog(*CurFnInfo); 171 EmitEndEHSpec(CurCodeDecl); 172 173 assert(EHStack.empty() && 174 "did not remove all scopes from cleanup stack!"); 175 176 // If someone did an indirect goto, emit the indirect goto block at the end of 177 // the function. 178 if (IndirectBranch) { 179 EmitBlock(IndirectBranch->getParent()); 180 Builder.ClearInsertionPoint(); 181 } 182 183 // Remove the AllocaInsertPt instruction, which is just a convenience for us. 184 llvm::Instruction *Ptr = AllocaInsertPt; 185 AllocaInsertPt = 0; 186 Ptr->eraseFromParent(); 187 188 // If someone took the address of a label but never did an indirect goto, we 189 // made a zero entry PHI node, which is illegal, zap it now. 190 if (IndirectBranch) { 191 llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress()); 192 if (PN->getNumIncomingValues() == 0) { 193 PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType())); 194 PN->eraseFromParent(); 195 } 196 } 197 198 EmitIfUsed(*this, EHResumeBlock); 199 EmitIfUsed(*this, TerminateLandingPad); 200 EmitIfUsed(*this, TerminateHandler); 201 EmitIfUsed(*this, UnreachableBlock); 202 203 if (CGM.getCodeGenOpts().EmitDeclMetadata) 204 EmitDeclMetadata(); 205 } 206 207 /// ShouldInstrumentFunction - Return true if the current function should be 208 /// instrumented with __cyg_profile_func_* calls 209 bool CodeGenFunction::ShouldInstrumentFunction() { 210 if (!CGM.getCodeGenOpts().InstrumentFunctions) 211 return false; 212 if (!CurFuncDecl || CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>()) 213 return false; 214 return true; 215 } 216 217 /// EmitFunctionInstrumentation - Emit LLVM code to call the specified 218 /// instrumentation function with the current function and the call site, if 219 /// function instrumentation is enabled. 220 void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) { 221 // void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site); 222 llvm::PointerType *PointerTy = Int8PtrTy; 223 llvm::Type *ProfileFuncArgs[] = { PointerTy, PointerTy }; 224 llvm::FunctionType *FunctionTy = 225 llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), 226 ProfileFuncArgs, false); 227 228 llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn); 229 llvm::CallInst *CallSite = Builder.CreateCall( 230 CGM.getIntrinsic(llvm::Intrinsic::returnaddress), 231 llvm::ConstantInt::get(Int32Ty, 0), 232 "callsite"); 233 234 Builder.CreateCall2(F, 235 llvm::ConstantExpr::getBitCast(CurFn, PointerTy), 236 CallSite); 237 } 238 239 void CodeGenFunction::EmitMCountInstrumentation() { 240 llvm::FunctionType *FTy = 241 llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), false); 242 243 llvm::Constant *MCountFn = CGM.CreateRuntimeFunction(FTy, 244 Target.getMCountName()); 245 Builder.CreateCall(MCountFn); 246 } 247 248 void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy, 249 llvm::Function *Fn, 250 const CGFunctionInfo &FnInfo, 251 const FunctionArgList &Args, 252 SourceLocation StartLoc) { 253 const Decl *D = GD.getDecl(); 254 255 DidCallStackSave = false; 256 CurCodeDecl = CurFuncDecl = D; 257 FnRetTy = RetTy; 258 CurFn = Fn; 259 CurFnInfo = &FnInfo; 260 assert(CurFn->isDeclaration() && "Function already has body?"); 261 262 // Pass inline keyword to optimizer if it appears explicitly on any 263 // declaration. 264 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) 265 for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(), 266 RE = FD->redecls_end(); RI != RE; ++RI) 267 if (RI->isInlineSpecified()) { 268 Fn->addFnAttr(llvm::Attribute::InlineHint); 269 break; 270 } 271 272 if (getContext().getLangOptions().OpenCL) { 273 // Add metadata for a kernel function. 274 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) 275 if (FD->hasAttr<OpenCLKernelAttr>()) { 276 llvm::LLVMContext &Context = getLLVMContext(); 277 llvm::NamedMDNode *OpenCLMetadata = 278 CGM.getModule().getOrInsertNamedMetadata("opencl.kernels"); 279 280 llvm::Value *Op = Fn; 281 OpenCLMetadata->addOperand(llvm::MDNode::get(Context, Op)); 282 } 283 } 284 285 llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn); 286 287 // Create a marker to make it easy to insert allocas into the entryblock 288 // later. Don't create this with the builder, because we don't want it 289 // folded. 290 llvm::Value *Undef = llvm::UndefValue::get(Int32Ty); 291 AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB); 292 if (Builder.isNamePreserving()) 293 AllocaInsertPt->setName("allocapt"); 294 295 ReturnBlock = getJumpDestInCurrentScope("return"); 296 297 Builder.SetInsertPoint(EntryBB); 298 299 // Emit subprogram debug descriptor. 300 if (CGDebugInfo *DI = getDebugInfo()) { 301 // FIXME: what is going on here and why does it ignore all these 302 // interesting type properties? 303 QualType FnType = 304 getContext().getFunctionType(RetTy, 0, 0, 305 FunctionProtoType::ExtProtoInfo()); 306 307 DI->setLocation(StartLoc); 308 DI->EmitFunctionStart(GD, FnType, CurFn, Builder); 309 } 310 311 if (ShouldInstrumentFunction()) 312 EmitFunctionInstrumentation("__cyg_profile_func_enter"); 313 314 if (CGM.getCodeGenOpts().InstrumentForProfiling) 315 EmitMCountInstrumentation(); 316 317 if (RetTy->isVoidType()) { 318 // Void type; nothing to return. 319 ReturnValue = 0; 320 } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect && 321 hasAggregateLLVMType(CurFnInfo->getReturnType())) { 322 // Indirect aggregate return; emit returned value directly into sret slot. 323 // This reduces code size, and affects correctness in C++. 324 ReturnValue = CurFn->arg_begin(); 325 } else { 326 ReturnValue = CreateIRTemp(RetTy, "retval"); 327 328 // Tell the epilog emitter to autorelease the result. We do this 329 // now so that various specialized functions can suppress it 330 // during their IR-generation. 331 if (getLangOptions().ObjCAutoRefCount && 332 !CurFnInfo->isReturnsRetained() && 333 RetTy->isObjCRetainableType()) 334 AutoreleaseResult = true; 335 } 336 337 EmitStartEHSpec(CurCodeDecl); 338 339 PrologueCleanupDepth = EHStack.stable_begin(); 340 EmitFunctionProlog(*CurFnInfo, CurFn, Args); 341 342 if (D && isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance()) 343 CGM.getCXXABI().EmitInstanceFunctionProlog(*this); 344 345 // If any of the arguments have a variably modified type, make sure to 346 // emit the type size. 347 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); 348 i != e; ++i) { 349 QualType Ty = (*i)->getType(); 350 351 if (Ty->isVariablyModifiedType()) 352 EmitVariablyModifiedType(Ty); 353 } 354 // Emit a location at the end of the prologue. 355 if (CGDebugInfo *DI = getDebugInfo()) 356 DI->EmitLocation(Builder, StartLoc); 357 } 358 359 void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) { 360 const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl()); 361 assert(FD->getBody()); 362 EmitStmt(FD->getBody()); 363 } 364 365 /// Tries to mark the given function nounwind based on the 366 /// non-existence of any throwing calls within it. We believe this is 367 /// lightweight enough to do at -O0. 368 static void TryMarkNoThrow(llvm::Function *F) { 369 // LLVM treats 'nounwind' on a function as part of the type, so we 370 // can't do this on functions that can be overwritten. 371 if (F->mayBeOverridden()) return; 372 373 for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI) 374 for (llvm::BasicBlock::iterator 375 BI = FI->begin(), BE = FI->end(); BI != BE; ++BI) 376 if (llvm::CallInst *Call = dyn_cast<llvm::CallInst>(&*BI)) { 377 if (!Call->doesNotThrow()) 378 return; 379 } else if (isa<llvm::ResumeInst>(&*BI)) { 380 return; 381 } 382 F->setDoesNotThrow(true); 383 } 384 385 void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn, 386 const CGFunctionInfo &FnInfo) { 387 const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl()); 388 389 // Check if we should generate debug info for this function. 390 if (CGM.getModuleDebugInfo() && !FD->hasAttr<NoDebugAttr>()) 391 DebugInfo = CGM.getModuleDebugInfo(); 392 393 FunctionArgList Args; 394 QualType ResTy = FD->getResultType(); 395 396 CurGD = GD; 397 if (isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isInstance()) 398 CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args); 399 400 if (FD->getNumParams()) 401 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) 402 Args.push_back(FD->getParamDecl(i)); 403 404 SourceRange BodyRange; 405 if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange(); 406 407 // Emit the standard function prologue. 408 StartFunction(GD, ResTy, Fn, FnInfo, Args, BodyRange.getBegin()); 409 410 // Generate the body of the function. 411 if (isa<CXXDestructorDecl>(FD)) 412 EmitDestructorBody(Args); 413 else if (isa<CXXConstructorDecl>(FD)) 414 EmitConstructorBody(Args); 415 else if (getContext().getLangOptions().CUDA && 416 !CGM.getCodeGenOpts().CUDAIsDevice && 417 FD->hasAttr<CUDAGlobalAttr>()) 418 CGM.getCUDARuntime().EmitDeviceStubBody(*this, Args); 419 else 420 EmitFunctionBody(Args); 421 422 // Emit the standard function epilogue. 423 FinishFunction(BodyRange.getEnd()); 424 425 // If we haven't marked the function nothrow through other means, do 426 // a quick pass now to see if we can. 427 if (!CurFn->doesNotThrow()) 428 TryMarkNoThrow(CurFn); 429 } 430 431 /// ContainsLabel - Return true if the statement contains a label in it. If 432 /// this statement is not executed normally, it not containing a label means 433 /// that we can just remove the code. 434 bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { 435 // Null statement, not a label! 436 if (S == 0) return false; 437 438 // If this is a label, we have to emit the code, consider something like: 439 // if (0) { ... foo: bar(); } goto foo; 440 // 441 // TODO: If anyone cared, we could track __label__'s, since we know that you 442 // can't jump to one from outside their declared region. 443 if (isa<LabelStmt>(S)) 444 return true; 445 446 // If this is a case/default statement, and we haven't seen a switch, we have 447 // to emit the code. 448 if (isa<SwitchCase>(S) && !IgnoreCaseStmts) 449 return true; 450 451 // If this is a switch statement, we want to ignore cases below it. 452 if (isa<SwitchStmt>(S)) 453 IgnoreCaseStmts = true; 454 455 // Scan subexpressions for verboten labels. 456 for (Stmt::const_child_range I = S->children(); I; ++I) 457 if (ContainsLabel(*I, IgnoreCaseStmts)) 458 return true; 459 460 return false; 461 } 462 463 /// containsBreak - Return true if the statement contains a break out of it. 464 /// If the statement (recursively) contains a switch or loop with a break 465 /// inside of it, this is fine. 466 bool CodeGenFunction::containsBreak(const Stmt *S) { 467 // Null statement, not a label! 468 if (S == 0) return false; 469 470 // If this is a switch or loop that defines its own break scope, then we can 471 // include it and anything inside of it. 472 if (isa<SwitchStmt>(S) || isa<WhileStmt>(S) || isa<DoStmt>(S) || 473 isa<ForStmt>(S)) 474 return false; 475 476 if (isa<BreakStmt>(S)) 477 return true; 478 479 // Scan subexpressions for verboten breaks. 480 for (Stmt::const_child_range I = S->children(); I; ++I) 481 if (containsBreak(*I)) 482 return true; 483 484 return false; 485 } 486 487 488 /// ConstantFoldsToSimpleInteger - If the specified expression does not fold 489 /// to a constant, or if it does but contains a label, return false. If it 490 /// constant folds return true and set the boolean result in Result. 491 bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond, 492 bool &ResultBool) { 493 llvm::APInt ResultInt; 494 if (!ConstantFoldsToSimpleInteger(Cond, ResultInt)) 495 return false; 496 497 ResultBool = ResultInt.getBoolValue(); 498 return true; 499 } 500 501 /// ConstantFoldsToSimpleInteger - If the specified expression does not fold 502 /// to a constant, or if it does but contains a label, return false. If it 503 /// constant folds return true and set the folded value. 504 bool CodeGenFunction:: 505 ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APInt &ResultInt) { 506 // FIXME: Rename and handle conversion of other evaluatable things 507 // to bool. 508 Expr::EvalResult Result; 509 if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() || 510 Result.HasSideEffects) 511 return false; // Not foldable, not integer or not fully evaluatable. 512 513 if (CodeGenFunction::ContainsLabel(Cond)) 514 return false; // Contains a label. 515 516 ResultInt = Result.Val.getInt(); 517 return true; 518 } 519 520 521 522 /// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if 523 /// statement) to the specified blocks. Based on the condition, this might try 524 /// to simplify the codegen of the conditional based on the branch. 525 /// 526 void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, 527 llvm::BasicBlock *TrueBlock, 528 llvm::BasicBlock *FalseBlock) { 529 Cond = Cond->IgnoreParens(); 530 531 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { 532 // Handle X && Y in a condition. 533 if (CondBOp->getOpcode() == BO_LAnd) { 534 // If we have "1 && X", simplify the code. "0 && X" would have constant 535 // folded if the case was simple enough. 536 bool ConstantBool = false; 537 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) && 538 ConstantBool) { 539 // br(1 && X) -> br(X). 540 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 541 } 542 543 // If we have "X && 1", simplify the code to use an uncond branch. 544 // "X && 0" would have been constant folded to 0. 545 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) && 546 ConstantBool) { 547 // br(X && 1) -> br(X). 548 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 549 } 550 551 // Emit the LHS as a conditional. If the LHS conditional is false, we 552 // want to jump to the FalseBlock. 553 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); 554 555 ConditionalEvaluation eval(*this); 556 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); 557 EmitBlock(LHSTrue); 558 559 // Any temporaries created here are conditional. 560 eval.begin(*this); 561 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 562 eval.end(*this); 563 564 return; 565 } 566 567 if (CondBOp->getOpcode() == BO_LOr) { 568 // If we have "0 || X", simplify the code. "1 || X" would have constant 569 // folded if the case was simple enough. 570 bool ConstantBool = false; 571 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) && 572 !ConstantBool) { 573 // br(0 || X) -> br(X). 574 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 575 } 576 577 // If we have "X || 0", simplify the code to use an uncond branch. 578 // "X || 1" would have been constant folded to 1. 579 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) && 580 !ConstantBool) { 581 // br(X || 0) -> br(X). 582 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 583 } 584 585 // Emit the LHS as a conditional. If the LHS conditional is true, we 586 // want to jump to the TrueBlock. 587 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); 588 589 ConditionalEvaluation eval(*this); 590 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); 591 EmitBlock(LHSFalse); 592 593 // Any temporaries created here are conditional. 594 eval.begin(*this); 595 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 596 eval.end(*this); 597 598 return; 599 } 600 } 601 602 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { 603 // br(!x, t, f) -> br(x, f, t) 604 if (CondUOp->getOpcode() == UO_LNot) 605 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); 606 } 607 608 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) { 609 // Handle ?: operator. 610 611 // Just ignore GNU ?: extension. 612 if (CondOp->getLHS()) { 613 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) 614 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); 615 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); 616 617 ConditionalEvaluation cond(*this); 618 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); 619 620 cond.begin(*this); 621 EmitBlock(LHSBlock); 622 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); 623 cond.end(*this); 624 625 cond.begin(*this); 626 EmitBlock(RHSBlock); 627 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); 628 cond.end(*this); 629 630 return; 631 } 632 } 633 634 // Emit the code with the fully general case. 635 llvm::Value *CondV = EvaluateExprAsBool(Cond); 636 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); 637 } 638 639 /// ErrorUnsupported - Print out an error that codegen doesn't support the 640 /// specified stmt yet. 641 void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, 642 bool OmitOnError) { 643 CGM.ErrorUnsupported(S, Type, OmitOnError); 644 } 645 646 /// emitNonZeroVLAInit - Emit the "zero" initialization of a 647 /// variable-length array whose elements have a non-zero bit-pattern. 648 /// 649 /// \param src - a char* pointing to the bit-pattern for a single 650 /// base element of the array 651 /// \param sizeInChars - the total size of the VLA, in chars 652 /// \param align - the total alignment of the VLA 653 static void emitNonZeroVLAInit(CodeGenFunction &CGF, QualType baseType, 654 llvm::Value *dest, llvm::Value *src, 655 llvm::Value *sizeInChars) { 656 std::pair<CharUnits,CharUnits> baseSizeAndAlign 657 = CGF.getContext().getTypeInfoInChars(baseType); 658 659 CGBuilderTy &Builder = CGF.Builder; 660 661 llvm::Value *baseSizeInChars 662 = llvm::ConstantInt::get(CGF.IntPtrTy, baseSizeAndAlign.first.getQuantity()); 663 664 llvm::Type *i8p = Builder.getInt8PtrTy(); 665 666 llvm::Value *begin = Builder.CreateBitCast(dest, i8p, "vla.begin"); 667 llvm::Value *end = Builder.CreateInBoundsGEP(dest, sizeInChars, "vla.end"); 668 669 llvm::BasicBlock *originBB = CGF.Builder.GetInsertBlock(); 670 llvm::BasicBlock *loopBB = CGF.createBasicBlock("vla-init.loop"); 671 llvm::BasicBlock *contBB = CGF.createBasicBlock("vla-init.cont"); 672 673 // Make a loop over the VLA. C99 guarantees that the VLA element 674 // count must be nonzero. 675 CGF.EmitBlock(loopBB); 676 677 llvm::PHINode *cur = Builder.CreatePHI(i8p, 2, "vla.cur"); 678 cur->addIncoming(begin, originBB); 679 680 // memcpy the individual element bit-pattern. 681 Builder.CreateMemCpy(cur, src, baseSizeInChars, 682 baseSizeAndAlign.second.getQuantity(), 683 /*volatile*/ false); 684 685 // Go to the next element. 686 llvm::Value *next = Builder.CreateConstInBoundsGEP1_32(cur, 1, "vla.next"); 687 688 // Leave if that's the end of the VLA. 689 llvm::Value *done = Builder.CreateICmpEQ(next, end, "vla-init.isdone"); 690 Builder.CreateCondBr(done, contBB, loopBB); 691 cur->addIncoming(next, loopBB); 692 693 CGF.EmitBlock(contBB); 694 } 695 696 void 697 CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) { 698 // Ignore empty classes in C++. 699 if (getContext().getLangOptions().CPlusPlus) { 700 if (const RecordType *RT = Ty->getAs<RecordType>()) { 701 if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty()) 702 return; 703 } 704 } 705 706 // Cast the dest ptr to the appropriate i8 pointer type. 707 unsigned DestAS = 708 cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace(); 709 llvm::Type *BP = Builder.getInt8PtrTy(DestAS); 710 if (DestPtr->getType() != BP) 711 DestPtr = Builder.CreateBitCast(DestPtr, BP); 712 713 // Get size and alignment info for this aggregate. 714 std::pair<CharUnits, CharUnits> TypeInfo = 715 getContext().getTypeInfoInChars(Ty); 716 CharUnits Size = TypeInfo.first; 717 CharUnits Align = TypeInfo.second; 718 719 llvm::Value *SizeVal; 720 const VariableArrayType *vla; 721 722 // Don't bother emitting a zero-byte memset. 723 if (Size.isZero()) { 724 // But note that getTypeInfo returns 0 for a VLA. 725 if (const VariableArrayType *vlaType = 726 dyn_cast_or_null<VariableArrayType>( 727 getContext().getAsArrayType(Ty))) { 728 QualType eltType; 729 llvm::Value *numElts; 730 llvm::tie(numElts, eltType) = getVLASize(vlaType); 731 732 SizeVal = numElts; 733 CharUnits eltSize = getContext().getTypeSizeInChars(eltType); 734 if (!eltSize.isOne()) 735 SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(eltSize)); 736 vla = vlaType; 737 } else { 738 return; 739 } 740 } else { 741 SizeVal = CGM.getSize(Size); 742 vla = 0; 743 } 744 745 // If the type contains a pointer to data member we can't memset it to zero. 746 // Instead, create a null constant and copy it to the destination. 747 // TODO: there are other patterns besides zero that we can usefully memset, 748 // like -1, which happens to be the pattern used by member-pointers. 749 if (!CGM.getTypes().isZeroInitializable(Ty)) { 750 // For a VLA, emit a single element, then splat that over the VLA. 751 if (vla) Ty = getContext().getBaseElementType(vla); 752 753 llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty); 754 755 llvm::GlobalVariable *NullVariable = 756 new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(), 757 /*isConstant=*/true, 758 llvm::GlobalVariable::PrivateLinkage, 759 NullConstant, Twine()); 760 llvm::Value *SrcPtr = 761 Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy()); 762 763 if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal); 764 765 // Get and call the appropriate llvm.memcpy overload. 766 Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align.getQuantity(), false); 767 return; 768 } 769 770 // Otherwise, just memset the whole thing to zero. This is legal 771 // because in LLVM, all default initializers (other than the ones we just 772 // handled above) are guaranteed to have a bit pattern of all zeros. 773 Builder.CreateMemSet(DestPtr, Builder.getInt8(0), SizeVal, 774 Align.getQuantity(), false); 775 } 776 777 llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *L) { 778 // Make sure that there is a block for the indirect goto. 779 if (IndirectBranch == 0) 780 GetIndirectGotoBlock(); 781 782 llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock(); 783 784 // Make sure the indirect branch includes all of the address-taken blocks. 785 IndirectBranch->addDestination(BB); 786 return llvm::BlockAddress::get(CurFn, BB); 787 } 788 789 llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() { 790 // If we already made the indirect branch for indirect goto, return its block. 791 if (IndirectBranch) return IndirectBranch->getParent(); 792 793 CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto")); 794 795 // Create the PHI node that indirect gotos will add entries to. 796 llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, 0, 797 "indirect.goto.dest"); 798 799 // Create the indirect branch instruction. 800 IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal); 801 return IndirectBranch->getParent(); 802 } 803 804 /// Computes the length of an array in elements, as well as the base 805 /// element type and a properly-typed first element pointer. 806 llvm::Value *CodeGenFunction::emitArrayLength(const ArrayType *origArrayType, 807 QualType &baseType, 808 llvm::Value *&addr) { 809 const ArrayType *arrayType = origArrayType; 810 811 // If it's a VLA, we have to load the stored size. Note that 812 // this is the size of the VLA in bytes, not its size in elements. 813 llvm::Value *numVLAElements = 0; 814 if (isa<VariableArrayType>(arrayType)) { 815 numVLAElements = getVLASize(cast<VariableArrayType>(arrayType)).first; 816 817 // Walk into all VLAs. This doesn't require changes to addr, 818 // which has type T* where T is the first non-VLA element type. 819 do { 820 QualType elementType = arrayType->getElementType(); 821 arrayType = getContext().getAsArrayType(elementType); 822 823 // If we only have VLA components, 'addr' requires no adjustment. 824 if (!arrayType) { 825 baseType = elementType; 826 return numVLAElements; 827 } 828 } while (isa<VariableArrayType>(arrayType)); 829 830 // We get out here only if we find a constant array type 831 // inside the VLA. 832 } 833 834 // We have some number of constant-length arrays, so addr should 835 // have LLVM type [M x [N x [...]]]*. Build a GEP that walks 836 // down to the first element of addr. 837 SmallVector<llvm::Value*, 8> gepIndices; 838 839 // GEP down to the array type. 840 llvm::ConstantInt *zero = Builder.getInt32(0); 841 gepIndices.push_back(zero); 842 843 // It's more efficient to calculate the count from the LLVM 844 // constant-length arrays than to re-evaluate the array bounds. 845 uint64_t countFromCLAs = 1; 846 847 llvm::ArrayType *llvmArrayType = 848 cast<llvm::ArrayType>( 849 cast<llvm::PointerType>(addr->getType())->getElementType()); 850 while (true) { 851 assert(isa<ConstantArrayType>(arrayType)); 852 assert(cast<ConstantArrayType>(arrayType)->getSize().getZExtValue() 853 == llvmArrayType->getNumElements()); 854 855 gepIndices.push_back(zero); 856 countFromCLAs *= llvmArrayType->getNumElements(); 857 858 llvmArrayType = 859 dyn_cast<llvm::ArrayType>(llvmArrayType->getElementType()); 860 if (!llvmArrayType) break; 861 862 arrayType = getContext().getAsArrayType(arrayType->getElementType()); 863 assert(arrayType && "LLVM and Clang types are out-of-synch"); 864 } 865 866 baseType = arrayType->getElementType(); 867 868 // Create the actual GEP. 869 addr = Builder.CreateInBoundsGEP(addr, gepIndices, "array.begin"); 870 871 llvm::Value *numElements 872 = llvm::ConstantInt::get(SizeTy, countFromCLAs); 873 874 // If we had any VLA dimensions, factor them in. 875 if (numVLAElements) 876 numElements = Builder.CreateNUWMul(numVLAElements, numElements); 877 878 return numElements; 879 } 880 881 std::pair<llvm::Value*, QualType> 882 CodeGenFunction::getVLASize(QualType type) { 883 const VariableArrayType *vla = getContext().getAsVariableArrayType(type); 884 assert(vla && "type was not a variable array type!"); 885 return getVLASize(vla); 886 } 887 888 std::pair<llvm::Value*, QualType> 889 CodeGenFunction::getVLASize(const VariableArrayType *type) { 890 // The number of elements so far; always size_t. 891 llvm::Value *numElements = 0; 892 893 QualType elementType; 894 do { 895 elementType = type->getElementType(); 896 llvm::Value *vlaSize = VLASizeMap[type->getSizeExpr()]; 897 assert(vlaSize && "no size for VLA!"); 898 assert(vlaSize->getType() == SizeTy); 899 900 if (!numElements) { 901 numElements = vlaSize; 902 } else { 903 // It's undefined behavior if this wraps around, so mark it that way. 904 numElements = Builder.CreateNUWMul(numElements, vlaSize); 905 } 906 } while ((type = getContext().getAsVariableArrayType(elementType))); 907 908 return std::pair<llvm::Value*,QualType>(numElements, elementType); 909 } 910 911 void CodeGenFunction::EmitVariablyModifiedType(QualType type) { 912 assert(type->isVariablyModifiedType() && 913 "Must pass variably modified type to EmitVLASizes!"); 914 915 EnsureInsertPoint(); 916 917 // We're going to walk down into the type and look for VLA 918 // expressions. 919 type = type.getCanonicalType(); 920 do { 921 assert(type->isVariablyModifiedType()); 922 923 const Type *ty = type.getTypePtr(); 924 switch (ty->getTypeClass()) { 925 #define TYPE(Class, Base) 926 #define ABSTRACT_TYPE(Class, Base) 927 #define NON_CANONICAL_TYPE(Class, Base) case Type::Class: 928 #define DEPENDENT_TYPE(Class, Base) case Type::Class: 929 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class: 930 #include "clang/AST/TypeNodes.def" 931 llvm_unreachable("unexpected dependent or non-canonical type!"); 932 933 // These types are never variably-modified. 934 case Type::Builtin: 935 case Type::Complex: 936 case Type::Vector: 937 case Type::ExtVector: 938 case Type::Record: 939 case Type::Enum: 940 case Type::ObjCObject: 941 case Type::ObjCInterface: 942 case Type::ObjCObjectPointer: 943 llvm_unreachable("type class is never variably-modified!"); 944 945 case Type::Pointer: 946 type = cast<PointerType>(ty)->getPointeeType(); 947 break; 948 949 case Type::BlockPointer: 950 type = cast<BlockPointerType>(ty)->getPointeeType(); 951 break; 952 953 case Type::LValueReference: 954 case Type::RValueReference: 955 type = cast<ReferenceType>(ty)->getPointeeType(); 956 break; 957 958 case Type::MemberPointer: 959 type = cast<MemberPointerType>(ty)->getPointeeType(); 960 break; 961 962 case Type::ConstantArray: 963 case Type::IncompleteArray: 964 // Losing element qualification here is fine. 965 type = cast<ArrayType>(ty)->getElementType(); 966 break; 967 968 case Type::VariableArray: { 969 // Losing element qualification here is fine. 970 const VariableArrayType *vat = cast<VariableArrayType>(ty); 971 972 // Unknown size indication requires no size computation. 973 // Otherwise, evaluate and record it. 974 if (const Expr *size = vat->getSizeExpr()) { 975 // It's possible that we might have emitted this already, 976 // e.g. with a typedef and a pointer to it. 977 llvm::Value *&entry = VLASizeMap[size]; 978 if (!entry) { 979 // Always zexting here would be wrong if it weren't 980 // undefined behavior to have a negative bound. 981 entry = Builder.CreateIntCast(EmitScalarExpr(size), SizeTy, 982 /*signed*/ false); 983 } 984 } 985 type = vat->getElementType(); 986 break; 987 } 988 989 case Type::FunctionProto: 990 case Type::FunctionNoProto: 991 type = cast<FunctionType>(ty)->getResultType(); 992 break; 993 994 case Type::Atomic: 995 type = cast<AtomicType>(ty)->getValueType(); 996 break; 997 } 998 } while (type->isVariablyModifiedType()); 999 } 1000 1001 llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { 1002 if (getContext().getBuiltinVaListType()->isArrayType()) 1003 return EmitScalarExpr(E); 1004 return EmitLValue(E).getAddress(); 1005 } 1006 1007 void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E, 1008 llvm::Constant *Init) { 1009 assert (Init && "Invalid DeclRefExpr initializer!"); 1010 if (CGDebugInfo *Dbg = getDebugInfo()) 1011 Dbg->EmitGlobalVariable(E->getDecl(), Init); 1012 } 1013 1014 CodeGenFunction::PeepholeProtection 1015 CodeGenFunction::protectFromPeepholes(RValue rvalue) { 1016 // At the moment, the only aggressive peephole we do in IR gen 1017 // is trunc(zext) folding, but if we add more, we can easily 1018 // extend this protection. 1019 1020 if (!rvalue.isScalar()) return PeepholeProtection(); 1021 llvm::Value *value = rvalue.getScalarVal(); 1022 if (!isa<llvm::ZExtInst>(value)) return PeepholeProtection(); 1023 1024 // Just make an extra bitcast. 1025 assert(HaveInsertPoint()); 1026 llvm::Instruction *inst = new llvm::BitCastInst(value, value->getType(), "", 1027 Builder.GetInsertBlock()); 1028 1029 PeepholeProtection protection; 1030 protection.Inst = inst; 1031 return protection; 1032 } 1033 1034 void CodeGenFunction::unprotectFromPeepholes(PeepholeProtection protection) { 1035 if (!protection.Inst) return; 1036 1037 // In theory, we could try to duplicate the peepholes now, but whatever. 1038 protection.Inst->eraseFromParent(); 1039 } 1040 1041 llvm::Value *CodeGenFunction::EmitAnnotationCall(llvm::Value *AnnotationFn, 1042 llvm::Value *AnnotatedVal, 1043 llvm::StringRef AnnotationStr, 1044 SourceLocation Location) { 1045 llvm::Value *Args[4] = { 1046 AnnotatedVal, 1047 Builder.CreateBitCast(CGM.EmitAnnotationString(AnnotationStr), Int8PtrTy), 1048 Builder.CreateBitCast(CGM.EmitAnnotationUnit(Location), Int8PtrTy), 1049 CGM.EmitAnnotationLineNo(Location) 1050 }; 1051 return Builder.CreateCall(AnnotationFn, Args); 1052 } 1053 1054 void CodeGenFunction::EmitVarAnnotations(const VarDecl *D, llvm::Value *V) { 1055 assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute"); 1056 // FIXME We create a new bitcast for every annotation because that's what 1057 // llvm-gcc was doing. 1058 for (specific_attr_iterator<AnnotateAttr> 1059 ai = D->specific_attr_begin<AnnotateAttr>(), 1060 ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai) 1061 EmitAnnotationCall(CGM.getIntrinsic(llvm::Intrinsic::var_annotation), 1062 Builder.CreateBitCast(V, CGM.Int8PtrTy, V->getName()), 1063 (*ai)->getAnnotation(), D->getLocation()); 1064 } 1065 1066 llvm::Value *CodeGenFunction::EmitFieldAnnotations(const FieldDecl *D, 1067 llvm::Value *V) { 1068 assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute"); 1069 llvm::Type *VTy = V->getType(); 1070 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::ptr_annotation, 1071 CGM.Int8PtrTy); 1072 1073 for (specific_attr_iterator<AnnotateAttr> 1074 ai = D->specific_attr_begin<AnnotateAttr>(), 1075 ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai) { 1076 // FIXME Always emit the cast inst so we can differentiate between 1077 // annotation on the first field of a struct and annotation on the struct 1078 // itself. 1079 if (VTy != CGM.Int8PtrTy) 1080 V = Builder.Insert(new llvm::BitCastInst(V, CGM.Int8PtrTy)); 1081 V = EmitAnnotationCall(F, V, (*ai)->getAnnotation(), D->getLocation()); 1082 V = Builder.CreateBitCast(V, VTy); 1083 } 1084 1085 return V; 1086 } 1087