CodeGenFunction.cpp revision 27dd7d962bbf774988bc5e59d04a7743ed503514
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 "clang/Basic/TargetInfo.h" 20#include "clang/AST/ASTContext.h" 21#include "clang/AST/Decl.h" 22#include "clang/AST/DeclCXX.h" 23#include "clang/AST/StmtCXX.h" 24#include "clang/Frontend/CodeGenOptions.h" 25#include "llvm/Target/TargetData.h" 26#include "llvm/Intrinsics.h" 27using namespace clang; 28using namespace CodeGen; 29 30CodeGenFunction::CodeGenFunction(CodeGenModule &cgm) 31 : CodeGenTypeCache(cgm), CGM(cgm), 32 Target(CGM.getContext().getTargetInfo()), 33 Builder(cgm.getModule().getContext()), 34 AutoreleaseResult(false), BlockInfo(0), BlockPointer(0), 35 LambdaThisCaptureField(0), NormalCleanupDest(0), NextCleanupDestIndex(1), 36 FirstBlockInfo(0), EHResumeBlock(0), ExceptionSlot(0), EHSelectorSlot(0), 37 DebugInfo(0), DisableDebugInfo(false), DidCallStackSave(false), 38 IndirectBranch(0), SwitchInsn(0), CaseRangeBlock(0), UnreachableBlock(0), 39 CXXABIThisDecl(0), CXXABIThisValue(0), CXXThisValue(0), CXXVTTDecl(0), 40 CXXVTTValue(0), OutermostConditional(0), TerminateLandingPad(0), 41 TerminateHandler(0), 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 const CXXMethodDecl *MD = cast<CXXMethodDecl>(D); 357 if (MD->getParent()->isLambda() && 358 MD->getOverloadedOperator() == OO_Call) { 359 // We're in a lambda; figure out the captures. 360 MD->getParent()->getCaptureFields(LambdaCaptureFields, 361 LambdaThisCaptureField); 362 if (LambdaThisCaptureField) { 363 // If this lambda captures this, load it. 364 LValue ThisLValue = EmitLValueForField(CXXABIThisValue, 365 LambdaThisCaptureField, 0); 366 CXXThisValue = EmitLoadOfLValue(ThisLValue).getScalarVal(); 367 } 368 } else { 369 // Not in a lambda; just use 'this' from the method. 370 // FIXME: Should we generate a new load for each use of 'this'? The 371 // fast register allocator would be happier... 372 CXXThisValue = CXXABIThisValue; 373 } 374 } 375 376 // If any of the arguments have a variably modified type, make sure to 377 // emit the type size. 378 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); 379 i != e; ++i) { 380 QualType Ty = (*i)->getType(); 381 382 if (Ty->isVariablyModifiedType()) 383 EmitVariablyModifiedType(Ty); 384 } 385 // Emit a location at the end of the prologue. 386 if (CGDebugInfo *DI = getDebugInfo()) 387 DI->EmitLocation(Builder, StartLoc); 388} 389 390void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) { 391 const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl()); 392 assert(FD->getBody()); 393 EmitStmt(FD->getBody()); 394} 395 396/// Tries to mark the given function nounwind based on the 397/// non-existence of any throwing calls within it. We believe this is 398/// lightweight enough to do at -O0. 399static void TryMarkNoThrow(llvm::Function *F) { 400 // LLVM treats 'nounwind' on a function as part of the type, so we 401 // can't do this on functions that can be overwritten. 402 if (F->mayBeOverridden()) return; 403 404 for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI) 405 for (llvm::BasicBlock::iterator 406 BI = FI->begin(), BE = FI->end(); BI != BE; ++BI) 407 if (llvm::CallInst *Call = dyn_cast<llvm::CallInst>(&*BI)) { 408 if (!Call->doesNotThrow()) 409 return; 410 } else if (isa<llvm::ResumeInst>(&*BI)) { 411 return; 412 } 413 F->setDoesNotThrow(true); 414} 415 416void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn, 417 const CGFunctionInfo &FnInfo) { 418 const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl()); 419 420 // Check if we should generate debug info for this function. 421 if (CGM.getModuleDebugInfo() && !FD->hasAttr<NoDebugAttr>()) 422 DebugInfo = CGM.getModuleDebugInfo(); 423 424 FunctionArgList Args; 425 QualType ResTy = FD->getResultType(); 426 427 CurGD = GD; 428 if (isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isInstance()) 429 CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args); 430 431 if (FD->getNumParams()) 432 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) 433 Args.push_back(FD->getParamDecl(i)); 434 435 SourceRange BodyRange; 436 if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange(); 437 438 // Emit the standard function prologue. 439 StartFunction(GD, ResTy, Fn, FnInfo, Args, BodyRange.getBegin()); 440 441 // Generate the body of the function. 442 if (isa<CXXDestructorDecl>(FD)) 443 EmitDestructorBody(Args); 444 else if (isa<CXXConstructorDecl>(FD)) 445 EmitConstructorBody(Args); 446 else if (getContext().getLangOptions().CUDA && 447 !CGM.getCodeGenOpts().CUDAIsDevice && 448 FD->hasAttr<CUDAGlobalAttr>()) 449 CGM.getCUDARuntime().EmitDeviceStubBody(*this, Args); 450 else if (isa<CXXConversionDecl>(FD) && 451 cast<CXXConversionDecl>(FD)->isLambdaToBlockPointerConversion()) { 452 // The lambda conversion to block pointer is special; the semantics can't be 453 // expressed in the AST, so IRGen needs to special-case it. 454 EmitLambdaToBlockPointerBody(Args); 455 } else if (isa<CXXMethodDecl>(FD) && 456 cast<CXXMethodDecl>(FD)->isLambdaStaticInvoker()) { 457 // The lambda "__invoke" function is special, because it forwards or 458 // clones the body of the function call operator (but is actually static). 459 EmitLambdaStaticInvokeFunction(cast<CXXMethodDecl>(FD)); 460 } 461 else 462 EmitFunctionBody(Args); 463 464 // Emit the standard function epilogue. 465 FinishFunction(BodyRange.getEnd()); 466 467 // If we haven't marked the function nothrow through other means, do 468 // a quick pass now to see if we can. 469 if (!CurFn->doesNotThrow()) 470 TryMarkNoThrow(CurFn); 471} 472 473/// ContainsLabel - Return true if the statement contains a label in it. If 474/// this statement is not executed normally, it not containing a label means 475/// that we can just remove the code. 476bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { 477 // Null statement, not a label! 478 if (S == 0) return false; 479 480 // If this is a label, we have to emit the code, consider something like: 481 // if (0) { ... foo: bar(); } goto foo; 482 // 483 // TODO: If anyone cared, we could track __label__'s, since we know that you 484 // can't jump to one from outside their declared region. 485 if (isa<LabelStmt>(S)) 486 return true; 487 488 // If this is a case/default statement, and we haven't seen a switch, we have 489 // to emit the code. 490 if (isa<SwitchCase>(S) && !IgnoreCaseStmts) 491 return true; 492 493 // If this is a switch statement, we want to ignore cases below it. 494 if (isa<SwitchStmt>(S)) 495 IgnoreCaseStmts = true; 496 497 // Scan subexpressions for verboten labels. 498 for (Stmt::const_child_range I = S->children(); I; ++I) 499 if (ContainsLabel(*I, IgnoreCaseStmts)) 500 return true; 501 502 return false; 503} 504 505/// containsBreak - Return true if the statement contains a break out of it. 506/// If the statement (recursively) contains a switch or loop with a break 507/// inside of it, this is fine. 508bool CodeGenFunction::containsBreak(const Stmt *S) { 509 // Null statement, not a label! 510 if (S == 0) return false; 511 512 // If this is a switch or loop that defines its own break scope, then we can 513 // include it and anything inside of it. 514 if (isa<SwitchStmt>(S) || isa<WhileStmt>(S) || isa<DoStmt>(S) || 515 isa<ForStmt>(S)) 516 return false; 517 518 if (isa<BreakStmt>(S)) 519 return true; 520 521 // Scan subexpressions for verboten breaks. 522 for (Stmt::const_child_range I = S->children(); I; ++I) 523 if (containsBreak(*I)) 524 return true; 525 526 return false; 527} 528 529 530/// ConstantFoldsToSimpleInteger - If the specified expression does not fold 531/// to a constant, or if it does but contains a label, return false. If it 532/// constant folds return true and set the boolean result in Result. 533bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond, 534 bool &ResultBool) { 535 llvm::APInt ResultInt; 536 if (!ConstantFoldsToSimpleInteger(Cond, ResultInt)) 537 return false; 538 539 ResultBool = ResultInt.getBoolValue(); 540 return true; 541} 542 543/// ConstantFoldsToSimpleInteger - If the specified expression does not fold 544/// to a constant, or if it does but contains a label, return false. If it 545/// constant folds return true and set the folded value. 546bool CodeGenFunction:: 547ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APInt &ResultInt) { 548 // FIXME: Rename and handle conversion of other evaluatable things 549 // to bool. 550 llvm::APSInt Int; 551 if (!Cond->EvaluateAsInt(Int, getContext())) 552 return false; // Not foldable, not integer or not fully evaluatable. 553 554 if (CodeGenFunction::ContainsLabel(Cond)) 555 return false; // Contains a label. 556 557 ResultInt = Int; 558 return true; 559} 560 561 562 563/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if 564/// statement) to the specified blocks. Based on the condition, this might try 565/// to simplify the codegen of the conditional based on the branch. 566/// 567void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, 568 llvm::BasicBlock *TrueBlock, 569 llvm::BasicBlock *FalseBlock) { 570 Cond = Cond->IgnoreParens(); 571 572 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { 573 // Handle X && Y in a condition. 574 if (CondBOp->getOpcode() == BO_LAnd) { 575 // If we have "1 && X", simplify the code. "0 && X" would have constant 576 // folded if the case was simple enough. 577 bool ConstantBool = false; 578 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) && 579 ConstantBool) { 580 // br(1 && X) -> br(X). 581 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 582 } 583 584 // If we have "X && 1", simplify the code to use an uncond branch. 585 // "X && 0" would have been constant folded to 0. 586 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) && 587 ConstantBool) { 588 // br(X && 1) -> br(X). 589 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 590 } 591 592 // Emit the LHS as a conditional. If the LHS conditional is false, we 593 // want to jump to the FalseBlock. 594 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); 595 596 ConditionalEvaluation eval(*this); 597 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); 598 EmitBlock(LHSTrue); 599 600 // Any temporaries created here are conditional. 601 eval.begin(*this); 602 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 603 eval.end(*this); 604 605 return; 606 } 607 608 if (CondBOp->getOpcode() == BO_LOr) { 609 // If we have "0 || X", simplify the code. "1 || X" would have constant 610 // folded if the case was simple enough. 611 bool ConstantBool = false; 612 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) && 613 !ConstantBool) { 614 // br(0 || X) -> br(X). 615 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 616 } 617 618 // If we have "X || 0", simplify the code to use an uncond branch. 619 // "X || 1" would have been constant folded to 1. 620 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) && 621 !ConstantBool) { 622 // br(X || 0) -> br(X). 623 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 624 } 625 626 // Emit the LHS as a conditional. If the LHS conditional is true, we 627 // want to jump to the TrueBlock. 628 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); 629 630 ConditionalEvaluation eval(*this); 631 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); 632 EmitBlock(LHSFalse); 633 634 // Any temporaries created here are conditional. 635 eval.begin(*this); 636 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 637 eval.end(*this); 638 639 return; 640 } 641 } 642 643 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { 644 // br(!x, t, f) -> br(x, f, t) 645 if (CondUOp->getOpcode() == UO_LNot) 646 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); 647 } 648 649 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) { 650 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) 651 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); 652 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); 653 654 ConditionalEvaluation cond(*this); 655 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); 656 657 cond.begin(*this); 658 EmitBlock(LHSBlock); 659 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); 660 cond.end(*this); 661 662 cond.begin(*this); 663 EmitBlock(RHSBlock); 664 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); 665 cond.end(*this); 666 667 return; 668 } 669 670 // Emit the code with the fully general case. 671 llvm::Value *CondV = EvaluateExprAsBool(Cond); 672 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); 673} 674 675/// ErrorUnsupported - Print out an error that codegen doesn't support the 676/// specified stmt yet. 677void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, 678 bool OmitOnError) { 679 CGM.ErrorUnsupported(S, Type, OmitOnError); 680} 681 682/// emitNonZeroVLAInit - Emit the "zero" initialization of a 683/// variable-length array whose elements have a non-zero bit-pattern. 684/// 685/// \param src - a char* pointing to the bit-pattern for a single 686/// base element of the array 687/// \param sizeInChars - the total size of the VLA, in chars 688/// \param align - the total alignment of the VLA 689static void emitNonZeroVLAInit(CodeGenFunction &CGF, QualType baseType, 690 llvm::Value *dest, llvm::Value *src, 691 llvm::Value *sizeInChars) { 692 std::pair<CharUnits,CharUnits> baseSizeAndAlign 693 = CGF.getContext().getTypeInfoInChars(baseType); 694 695 CGBuilderTy &Builder = CGF.Builder; 696 697 llvm::Value *baseSizeInChars 698 = llvm::ConstantInt::get(CGF.IntPtrTy, baseSizeAndAlign.first.getQuantity()); 699 700 llvm::Type *i8p = Builder.getInt8PtrTy(); 701 702 llvm::Value *begin = Builder.CreateBitCast(dest, i8p, "vla.begin"); 703 llvm::Value *end = Builder.CreateInBoundsGEP(dest, sizeInChars, "vla.end"); 704 705 llvm::BasicBlock *originBB = CGF.Builder.GetInsertBlock(); 706 llvm::BasicBlock *loopBB = CGF.createBasicBlock("vla-init.loop"); 707 llvm::BasicBlock *contBB = CGF.createBasicBlock("vla-init.cont"); 708 709 // Make a loop over the VLA. C99 guarantees that the VLA element 710 // count must be nonzero. 711 CGF.EmitBlock(loopBB); 712 713 llvm::PHINode *cur = Builder.CreatePHI(i8p, 2, "vla.cur"); 714 cur->addIncoming(begin, originBB); 715 716 // memcpy the individual element bit-pattern. 717 Builder.CreateMemCpy(cur, src, baseSizeInChars, 718 baseSizeAndAlign.second.getQuantity(), 719 /*volatile*/ false); 720 721 // Go to the next element. 722 llvm::Value *next = Builder.CreateConstInBoundsGEP1_32(cur, 1, "vla.next"); 723 724 // Leave if that's the end of the VLA. 725 llvm::Value *done = Builder.CreateICmpEQ(next, end, "vla-init.isdone"); 726 Builder.CreateCondBr(done, contBB, loopBB); 727 cur->addIncoming(next, loopBB); 728 729 CGF.EmitBlock(contBB); 730} 731 732void 733CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) { 734 // Ignore empty classes in C++. 735 if (getContext().getLangOptions().CPlusPlus) { 736 if (const RecordType *RT = Ty->getAs<RecordType>()) { 737 if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty()) 738 return; 739 } 740 } 741 742 // Cast the dest ptr to the appropriate i8 pointer type. 743 unsigned DestAS = 744 cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace(); 745 llvm::Type *BP = Builder.getInt8PtrTy(DestAS); 746 if (DestPtr->getType() != BP) 747 DestPtr = Builder.CreateBitCast(DestPtr, BP); 748 749 // Get size and alignment info for this aggregate. 750 std::pair<CharUnits, CharUnits> TypeInfo = 751 getContext().getTypeInfoInChars(Ty); 752 CharUnits Size = TypeInfo.first; 753 CharUnits Align = TypeInfo.second; 754 755 llvm::Value *SizeVal; 756 const VariableArrayType *vla; 757 758 // Don't bother emitting a zero-byte memset. 759 if (Size.isZero()) { 760 // But note that getTypeInfo returns 0 for a VLA. 761 if (const VariableArrayType *vlaType = 762 dyn_cast_or_null<VariableArrayType>( 763 getContext().getAsArrayType(Ty))) { 764 QualType eltType; 765 llvm::Value *numElts; 766 llvm::tie(numElts, eltType) = getVLASize(vlaType); 767 768 SizeVal = numElts; 769 CharUnits eltSize = getContext().getTypeSizeInChars(eltType); 770 if (!eltSize.isOne()) 771 SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(eltSize)); 772 vla = vlaType; 773 } else { 774 return; 775 } 776 } else { 777 SizeVal = CGM.getSize(Size); 778 vla = 0; 779 } 780 781 // If the type contains a pointer to data member we can't memset it to zero. 782 // Instead, create a null constant and copy it to the destination. 783 // TODO: there are other patterns besides zero that we can usefully memset, 784 // like -1, which happens to be the pattern used by member-pointers. 785 if (!CGM.getTypes().isZeroInitializable(Ty)) { 786 // For a VLA, emit a single element, then splat that over the VLA. 787 if (vla) Ty = getContext().getBaseElementType(vla); 788 789 llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty); 790 791 llvm::GlobalVariable *NullVariable = 792 new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(), 793 /*isConstant=*/true, 794 llvm::GlobalVariable::PrivateLinkage, 795 NullConstant, Twine()); 796 llvm::Value *SrcPtr = 797 Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy()); 798 799 if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal); 800 801 // Get and call the appropriate llvm.memcpy overload. 802 Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align.getQuantity(), false); 803 return; 804 } 805 806 // Otherwise, just memset the whole thing to zero. This is legal 807 // because in LLVM, all default initializers (other than the ones we just 808 // handled above) are guaranteed to have a bit pattern of all zeros. 809 Builder.CreateMemSet(DestPtr, Builder.getInt8(0), SizeVal, 810 Align.getQuantity(), false); 811} 812 813llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *L) { 814 // Make sure that there is a block for the indirect goto. 815 if (IndirectBranch == 0) 816 GetIndirectGotoBlock(); 817 818 llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock(); 819 820 // Make sure the indirect branch includes all of the address-taken blocks. 821 IndirectBranch->addDestination(BB); 822 return llvm::BlockAddress::get(CurFn, BB); 823} 824 825llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() { 826 // If we already made the indirect branch for indirect goto, return its block. 827 if (IndirectBranch) return IndirectBranch->getParent(); 828 829 CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto")); 830 831 // Create the PHI node that indirect gotos will add entries to. 832 llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, 0, 833 "indirect.goto.dest"); 834 835 // Create the indirect branch instruction. 836 IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal); 837 return IndirectBranch->getParent(); 838} 839 840/// Computes the length of an array in elements, as well as the base 841/// element type and a properly-typed first element pointer. 842llvm::Value *CodeGenFunction::emitArrayLength(const ArrayType *origArrayType, 843 QualType &baseType, 844 llvm::Value *&addr) { 845 const ArrayType *arrayType = origArrayType; 846 847 // If it's a VLA, we have to load the stored size. Note that 848 // this is the size of the VLA in bytes, not its size in elements. 849 llvm::Value *numVLAElements = 0; 850 if (isa<VariableArrayType>(arrayType)) { 851 numVLAElements = getVLASize(cast<VariableArrayType>(arrayType)).first; 852 853 // Walk into all VLAs. This doesn't require changes to addr, 854 // which has type T* where T is the first non-VLA element type. 855 do { 856 QualType elementType = arrayType->getElementType(); 857 arrayType = getContext().getAsArrayType(elementType); 858 859 // If we only have VLA components, 'addr' requires no adjustment. 860 if (!arrayType) { 861 baseType = elementType; 862 return numVLAElements; 863 } 864 } while (isa<VariableArrayType>(arrayType)); 865 866 // We get out here only if we find a constant array type 867 // inside the VLA. 868 } 869 870 // We have some number of constant-length arrays, so addr should 871 // have LLVM type [M x [N x [...]]]*. Build a GEP that walks 872 // down to the first element of addr. 873 SmallVector<llvm::Value*, 8> gepIndices; 874 875 // GEP down to the array type. 876 llvm::ConstantInt *zero = Builder.getInt32(0); 877 gepIndices.push_back(zero); 878 879 // It's more efficient to calculate the count from the LLVM 880 // constant-length arrays than to re-evaluate the array bounds. 881 uint64_t countFromCLAs = 1; 882 883 llvm::ArrayType *llvmArrayType = 884 cast<llvm::ArrayType>( 885 cast<llvm::PointerType>(addr->getType())->getElementType()); 886 while (true) { 887 assert(isa<ConstantArrayType>(arrayType)); 888 assert(cast<ConstantArrayType>(arrayType)->getSize().getZExtValue() 889 == llvmArrayType->getNumElements()); 890 891 gepIndices.push_back(zero); 892 countFromCLAs *= llvmArrayType->getNumElements(); 893 894 llvmArrayType = 895 dyn_cast<llvm::ArrayType>(llvmArrayType->getElementType()); 896 if (!llvmArrayType) break; 897 898 arrayType = getContext().getAsArrayType(arrayType->getElementType()); 899 assert(arrayType && "LLVM and Clang types are out-of-synch"); 900 } 901 902 baseType = arrayType->getElementType(); 903 904 // Create the actual GEP. 905 addr = Builder.CreateInBoundsGEP(addr, gepIndices, "array.begin"); 906 907 llvm::Value *numElements 908 = llvm::ConstantInt::get(SizeTy, countFromCLAs); 909 910 // If we had any VLA dimensions, factor them in. 911 if (numVLAElements) 912 numElements = Builder.CreateNUWMul(numVLAElements, numElements); 913 914 return numElements; 915} 916 917std::pair<llvm::Value*, QualType> 918CodeGenFunction::getVLASize(QualType type) { 919 const VariableArrayType *vla = getContext().getAsVariableArrayType(type); 920 assert(vla && "type was not a variable array type!"); 921 return getVLASize(vla); 922} 923 924std::pair<llvm::Value*, QualType> 925CodeGenFunction::getVLASize(const VariableArrayType *type) { 926 // The number of elements so far; always size_t. 927 llvm::Value *numElements = 0; 928 929 QualType elementType; 930 do { 931 elementType = type->getElementType(); 932 llvm::Value *vlaSize = VLASizeMap[type->getSizeExpr()]; 933 assert(vlaSize && "no size for VLA!"); 934 assert(vlaSize->getType() == SizeTy); 935 936 if (!numElements) { 937 numElements = vlaSize; 938 } else { 939 // It's undefined behavior if this wraps around, so mark it that way. 940 numElements = Builder.CreateNUWMul(numElements, vlaSize); 941 } 942 } while ((type = getContext().getAsVariableArrayType(elementType))); 943 944 return std::pair<llvm::Value*,QualType>(numElements, elementType); 945} 946 947void CodeGenFunction::EmitVariablyModifiedType(QualType type) { 948 assert(type->isVariablyModifiedType() && 949 "Must pass variably modified type to EmitVLASizes!"); 950 951 EnsureInsertPoint(); 952 953 // We're going to walk down into the type and look for VLA 954 // expressions. 955 do { 956 assert(type->isVariablyModifiedType()); 957 958 const Type *ty = type.getTypePtr(); 959 switch (ty->getTypeClass()) { 960 961#define TYPE(Class, Base) 962#define ABSTRACT_TYPE(Class, Base) 963#define NON_CANONICAL_TYPE(Class, Base) 964#define DEPENDENT_TYPE(Class, Base) case Type::Class: 965#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) 966#include "clang/AST/TypeNodes.def" 967 llvm_unreachable("unexpected dependent type!"); 968 969 // These types are never variably-modified. 970 case Type::Builtin: 971 case Type::Complex: 972 case Type::Vector: 973 case Type::ExtVector: 974 case Type::Record: 975 case Type::Enum: 976 case Type::Elaborated: 977 case Type::TemplateSpecialization: 978 case Type::ObjCObject: 979 case Type::ObjCInterface: 980 case Type::ObjCObjectPointer: 981 llvm_unreachable("type class is never variably-modified!"); 982 983 case Type::Pointer: 984 type = cast<PointerType>(ty)->getPointeeType(); 985 break; 986 987 case Type::BlockPointer: 988 type = cast<BlockPointerType>(ty)->getPointeeType(); 989 break; 990 991 case Type::LValueReference: 992 case Type::RValueReference: 993 type = cast<ReferenceType>(ty)->getPointeeType(); 994 break; 995 996 case Type::MemberPointer: 997 type = cast<MemberPointerType>(ty)->getPointeeType(); 998 break; 999 1000 case Type::ConstantArray: 1001 case Type::IncompleteArray: 1002 // Losing element qualification here is fine. 1003 type = cast<ArrayType>(ty)->getElementType(); 1004 break; 1005 1006 case Type::VariableArray: { 1007 // Losing element qualification here is fine. 1008 const VariableArrayType *vat = cast<VariableArrayType>(ty); 1009 1010 // Unknown size indication requires no size computation. 1011 // Otherwise, evaluate and record it. 1012 if (const Expr *size = vat->getSizeExpr()) { 1013 // It's possible that we might have emitted this already, 1014 // e.g. with a typedef and a pointer to it. 1015 llvm::Value *&entry = VLASizeMap[size]; 1016 if (!entry) { 1017 // Always zexting here would be wrong if it weren't 1018 // undefined behavior to have a negative bound. 1019 entry = Builder.CreateIntCast(EmitScalarExpr(size), SizeTy, 1020 /*signed*/ false); 1021 } 1022 } 1023 type = vat->getElementType(); 1024 break; 1025 } 1026 1027 case Type::FunctionProto: 1028 case Type::FunctionNoProto: 1029 type = cast<FunctionType>(ty)->getResultType(); 1030 break; 1031 1032 case Type::Paren: 1033 case Type::TypeOf: 1034 case Type::UnaryTransform: 1035 case Type::Attributed: 1036 case Type::SubstTemplateTypeParm: 1037 // Keep walking after single level desugaring. 1038 type = type.getSingleStepDesugaredType(getContext()); 1039 break; 1040 1041 case Type::Typedef: 1042 case Type::Decltype: 1043 case Type::Auto: 1044 // Stop walking: nothing to do. 1045 return; 1046 1047 case Type::TypeOfExpr: 1048 // Stop walking: emit typeof expression. 1049 EmitIgnoredExpr(cast<TypeOfExprType>(ty)->getUnderlyingExpr()); 1050 return; 1051 1052 case Type::Atomic: 1053 type = cast<AtomicType>(ty)->getValueType(); 1054 break; 1055 } 1056 } while (type->isVariablyModifiedType()); 1057} 1058 1059llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { 1060 if (getContext().getBuiltinVaListType()->isArrayType()) 1061 return EmitScalarExpr(E); 1062 return EmitLValue(E).getAddress(); 1063} 1064 1065void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E, 1066 llvm::Constant *Init) { 1067 assert (Init && "Invalid DeclRefExpr initializer!"); 1068 if (CGDebugInfo *Dbg = getDebugInfo()) 1069 Dbg->EmitGlobalVariable(E->getDecl(), Init); 1070} 1071 1072CodeGenFunction::PeepholeProtection 1073CodeGenFunction::protectFromPeepholes(RValue rvalue) { 1074 // At the moment, the only aggressive peephole we do in IR gen 1075 // is trunc(zext) folding, but if we add more, we can easily 1076 // extend this protection. 1077 1078 if (!rvalue.isScalar()) return PeepholeProtection(); 1079 llvm::Value *value = rvalue.getScalarVal(); 1080 if (!isa<llvm::ZExtInst>(value)) return PeepholeProtection(); 1081 1082 // Just make an extra bitcast. 1083 assert(HaveInsertPoint()); 1084 llvm::Instruction *inst = new llvm::BitCastInst(value, value->getType(), "", 1085 Builder.GetInsertBlock()); 1086 1087 PeepholeProtection protection; 1088 protection.Inst = inst; 1089 return protection; 1090} 1091 1092void CodeGenFunction::unprotectFromPeepholes(PeepholeProtection protection) { 1093 if (!protection.Inst) return; 1094 1095 // In theory, we could try to duplicate the peepholes now, but whatever. 1096 protection.Inst->eraseFromParent(); 1097} 1098 1099llvm::Value *CodeGenFunction::EmitAnnotationCall(llvm::Value *AnnotationFn, 1100 llvm::Value *AnnotatedVal, 1101 llvm::StringRef AnnotationStr, 1102 SourceLocation Location) { 1103 llvm::Value *Args[4] = { 1104 AnnotatedVal, 1105 Builder.CreateBitCast(CGM.EmitAnnotationString(AnnotationStr), Int8PtrTy), 1106 Builder.CreateBitCast(CGM.EmitAnnotationUnit(Location), Int8PtrTy), 1107 CGM.EmitAnnotationLineNo(Location) 1108 }; 1109 return Builder.CreateCall(AnnotationFn, Args); 1110} 1111 1112void CodeGenFunction::EmitVarAnnotations(const VarDecl *D, llvm::Value *V) { 1113 assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute"); 1114 // FIXME We create a new bitcast for every annotation because that's what 1115 // llvm-gcc was doing. 1116 for (specific_attr_iterator<AnnotateAttr> 1117 ai = D->specific_attr_begin<AnnotateAttr>(), 1118 ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai) 1119 EmitAnnotationCall(CGM.getIntrinsic(llvm::Intrinsic::var_annotation), 1120 Builder.CreateBitCast(V, CGM.Int8PtrTy, V->getName()), 1121 (*ai)->getAnnotation(), D->getLocation()); 1122} 1123 1124llvm::Value *CodeGenFunction::EmitFieldAnnotations(const FieldDecl *D, 1125 llvm::Value *V) { 1126 assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute"); 1127 llvm::Type *VTy = V->getType(); 1128 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::ptr_annotation, 1129 CGM.Int8PtrTy); 1130 1131 for (specific_attr_iterator<AnnotateAttr> 1132 ai = D->specific_attr_begin<AnnotateAttr>(), 1133 ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai) { 1134 // FIXME Always emit the cast inst so we can differentiate between 1135 // annotation on the first field of a struct and annotation on the struct 1136 // itself. 1137 if (VTy != CGM.Int8PtrTy) 1138 V = Builder.Insert(new llvm::BitCastInst(V, CGM.Int8PtrTy)); 1139 V = EmitAnnotationCall(F, V, (*ai)->getAnnotation(), D->getLocation()); 1140 V = Builder.CreateBitCast(V, VTy); 1141 } 1142 1143 return V; 1144} 1145