CodeGenFunction.cpp revision 221345
1//===--- CodeGenFunction.cpp - Emit LLVM Code from ASTs for a Function ----===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This coordinates the per-function state used while generating code. 11// 12//===----------------------------------------------------------------------===// 13 14#include "CodeGenFunction.h" 15#include "CodeGenModule.h" 16#include "CGCXXABI.h" 17#include "CGDebugInfo.h" 18#include "CGException.h" 19#include "clang/Basic/TargetInfo.h" 20#include "clang/AST/APValue.h" 21#include "clang/AST/ASTContext.h" 22#include "clang/AST/Decl.h" 23#include "clang/AST/DeclCXX.h" 24#include "clang/AST/StmtCXX.h" 25#include "clang/Frontend/CodeGenOptions.h" 26#include "llvm/Target/TargetData.h" 27#include "llvm/Intrinsics.h" 28using namespace clang; 29using namespace CodeGen; 30 31CodeGenFunction::CodeGenFunction(CodeGenModule &cgm) 32 : CodeGenTypeCache(cgm), CGM(cgm), 33 Target(CGM.getContext().Target), Builder(cgm.getModule().getContext()), 34 BlockInfo(0), BlockPointer(0), 35 NormalCleanupDest(0), EHCleanupDest(0), NextCleanupDestIndex(1), 36 ExceptionSlot(0), DebugInfo(0), DisableDebugInfo(false), IndirectBranch(0), 37 SwitchInsn(0), CaseRangeBlock(0), 38 DidCallStackSave(false), 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 47ASTContext &CodeGenFunction::getContext() const { 48 return CGM.getContext(); 49} 50 51 52const llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) { 53 return CGM.getTypes().ConvertTypeForMem(T); 54} 55 56const llvm::Type *CodeGenFunction::ConvertType(QualType T) { 57 return CGM.getTypes().ConvertType(T); 58} 59 60bool CodeGenFunction::hasAggregateLLVMType(QualType T) { 61 return T->isRecordType() || T->isArrayType() || T->isAnyComplexType() || 62 T->isObjCObjectType(); 63} 64 65void CodeGenFunction::EmitReturnBlock() { 66 // For cleanliness, we try to avoid emitting the return block for 67 // simple cases. 68 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 69 70 if (CurBB) { 71 assert(!CurBB->getTerminator() && "Unexpected terminated block."); 72 73 // We have a valid insert point, reuse it if it is empty or there are no 74 // explicit jumps to the return block. 75 if (CurBB->empty() || ReturnBlock.getBlock()->use_empty()) { 76 ReturnBlock.getBlock()->replaceAllUsesWith(CurBB); 77 delete ReturnBlock.getBlock(); 78 } else 79 EmitBlock(ReturnBlock.getBlock()); 80 return; 81 } 82 83 // Otherwise, if the return block is the target of a single direct 84 // branch then we can just put the code in that block instead. This 85 // cleans up functions which started with a unified return block. 86 if (ReturnBlock.getBlock()->hasOneUse()) { 87 llvm::BranchInst *BI = 88 dyn_cast<llvm::BranchInst>(*ReturnBlock.getBlock()->use_begin()); 89 if (BI && BI->isUnconditional() && 90 BI->getSuccessor(0) == ReturnBlock.getBlock()) { 91 // Reset insertion point and delete the branch. 92 Builder.SetInsertPoint(BI->getParent()); 93 BI->eraseFromParent(); 94 delete ReturnBlock.getBlock(); 95 return; 96 } 97 } 98 99 // FIXME: We are at an unreachable point, there is no reason to emit the block 100 // unless it has uses. However, we still need a place to put the debug 101 // region.end for now. 102 103 EmitBlock(ReturnBlock.getBlock()); 104} 105 106static void EmitIfUsed(CodeGenFunction &CGF, llvm::BasicBlock *BB) { 107 if (!BB) return; 108 if (!BB->use_empty()) 109 return CGF.CurFn->getBasicBlockList().push_back(BB); 110 delete BB; 111} 112 113void CodeGenFunction::FinishFunction(SourceLocation EndLoc) { 114 assert(BreakContinueStack.empty() && 115 "mismatched push/pop in break/continue stack!"); 116 117 // Emit function epilog (to return). 118 EmitReturnBlock(); 119 120 if (ShouldInstrumentFunction()) 121 EmitFunctionInstrumentation("__cyg_profile_func_exit"); 122 123 // Emit debug descriptor for function end. 124 if (CGDebugInfo *DI = getDebugInfo()) { 125 DI->setLocation(EndLoc); 126 DI->EmitFunctionEnd(Builder); 127 } 128 129 EmitFunctionEpilog(*CurFnInfo); 130 EmitEndEHSpec(CurCodeDecl); 131 132 assert(EHStack.empty() && 133 "did not remove all scopes from cleanup stack!"); 134 135 // If someone did an indirect goto, emit the indirect goto block at the end of 136 // the function. 137 if (IndirectBranch) { 138 EmitBlock(IndirectBranch->getParent()); 139 Builder.ClearInsertionPoint(); 140 } 141 142 // Remove the AllocaInsertPt instruction, which is just a convenience for us. 143 llvm::Instruction *Ptr = AllocaInsertPt; 144 AllocaInsertPt = 0; 145 Ptr->eraseFromParent(); 146 147 // If someone took the address of a label but never did an indirect goto, we 148 // made a zero entry PHI node, which is illegal, zap it now. 149 if (IndirectBranch) { 150 llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress()); 151 if (PN->getNumIncomingValues() == 0) { 152 PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType())); 153 PN->eraseFromParent(); 154 } 155 } 156 157 EmitIfUsed(*this, RethrowBlock.getBlock()); 158 EmitIfUsed(*this, TerminateLandingPad); 159 EmitIfUsed(*this, TerminateHandler); 160 EmitIfUsed(*this, UnreachableBlock); 161 162 if (CGM.getCodeGenOpts().EmitDeclMetadata) 163 EmitDeclMetadata(); 164} 165 166/// ShouldInstrumentFunction - Return true if the current function should be 167/// instrumented with __cyg_profile_func_* calls 168bool CodeGenFunction::ShouldInstrumentFunction() { 169 if (!CGM.getCodeGenOpts().InstrumentFunctions) 170 return false; 171 if (CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>()) 172 return false; 173 return true; 174} 175 176/// EmitFunctionInstrumentation - Emit LLVM code to call the specified 177/// instrumentation function with the current function and the call site, if 178/// function instrumentation is enabled. 179void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) { 180 const llvm::PointerType *PointerTy; 181 const llvm::FunctionType *FunctionTy; 182 std::vector<const llvm::Type*> ProfileFuncArgs; 183 184 // void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site); 185 PointerTy = Int8PtrTy; 186 ProfileFuncArgs.push_back(PointerTy); 187 ProfileFuncArgs.push_back(PointerTy); 188 FunctionTy = llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), 189 ProfileFuncArgs, false); 190 191 llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn); 192 llvm::CallInst *CallSite = Builder.CreateCall( 193 CGM.getIntrinsic(llvm::Intrinsic::returnaddress, 0, 0), 194 llvm::ConstantInt::get(Int32Ty, 0), 195 "callsite"); 196 197 Builder.CreateCall2(F, 198 llvm::ConstantExpr::getBitCast(CurFn, PointerTy), 199 CallSite); 200} 201 202void CodeGenFunction::EmitMCountInstrumentation() { 203 llvm::FunctionType *FTy = 204 llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), false); 205 206 llvm::Constant *MCountFn = CGM.CreateRuntimeFunction(FTy, 207 Target.getMCountName()); 208 Builder.CreateCall(MCountFn); 209} 210 211void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy, 212 llvm::Function *Fn, 213 const CGFunctionInfo &FnInfo, 214 const FunctionArgList &Args, 215 SourceLocation StartLoc) { 216 const Decl *D = GD.getDecl(); 217 218 DidCallStackSave = false; 219 CurCodeDecl = CurFuncDecl = D; 220 FnRetTy = RetTy; 221 CurFn = Fn; 222 CurFnInfo = &FnInfo; 223 assert(CurFn->isDeclaration() && "Function already has body?"); 224 225 // Pass inline keyword to optimizer if it appears explicitly on any 226 // declaration. 227 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) 228 for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(), 229 RE = FD->redecls_end(); RI != RE; ++RI) 230 if (RI->isInlineSpecified()) { 231 Fn->addFnAttr(llvm::Attribute::InlineHint); 232 break; 233 } 234 235 if (getContext().getLangOptions().OpenCL) { 236 // Add metadata for a kernel function. 237 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) 238 if (FD->hasAttr<OpenCLKernelAttr>()) { 239 llvm::LLVMContext &Context = getLLVMContext(); 240 llvm::NamedMDNode *OpenCLMetadata = 241 CGM.getModule().getOrInsertNamedMetadata("opencl.kernels"); 242 243 llvm::Value *Op = Fn; 244 OpenCLMetadata->addOperand(llvm::MDNode::get(Context, Op)); 245 } 246 } 247 248 llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn); 249 250 // Create a marker to make it easy to insert allocas into the entryblock 251 // later. Don't create this with the builder, because we don't want it 252 // folded. 253 llvm::Value *Undef = llvm::UndefValue::get(Int32Ty); 254 AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB); 255 if (Builder.isNamePreserving()) 256 AllocaInsertPt->setName("allocapt"); 257 258 ReturnBlock = getJumpDestInCurrentScope("return"); 259 260 Builder.SetInsertPoint(EntryBB); 261 262 // Emit subprogram debug descriptor. 263 if (CGDebugInfo *DI = getDebugInfo()) { 264 // FIXME: what is going on here and why does it ignore all these 265 // interesting type properties? 266 QualType FnType = 267 getContext().getFunctionType(RetTy, 0, 0, 268 FunctionProtoType::ExtProtoInfo()); 269 270 DI->setLocation(StartLoc); 271 DI->EmitFunctionStart(GD, FnType, CurFn, Builder); 272 } 273 274 if (ShouldInstrumentFunction()) 275 EmitFunctionInstrumentation("__cyg_profile_func_enter"); 276 277 if (CGM.getCodeGenOpts().InstrumentForProfiling) 278 EmitMCountInstrumentation(); 279 280 if (RetTy->isVoidType()) { 281 // Void type; nothing to return. 282 ReturnValue = 0; 283 } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect && 284 hasAggregateLLVMType(CurFnInfo->getReturnType())) { 285 // Indirect aggregate return; emit returned value directly into sret slot. 286 // This reduces code size, and affects correctness in C++. 287 ReturnValue = CurFn->arg_begin(); 288 } else { 289 ReturnValue = CreateIRTemp(RetTy, "retval"); 290 } 291 292 EmitStartEHSpec(CurCodeDecl); 293 EmitFunctionProlog(*CurFnInfo, CurFn, Args); 294 295 if (D && isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance()) 296 CGM.getCXXABI().EmitInstanceFunctionProlog(*this); 297 298 // If any of the arguments have a variably modified type, make sure to 299 // emit the type size. 300 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); 301 i != e; ++i) { 302 QualType Ty = (*i)->getType(); 303 304 if (Ty->isVariablyModifiedType()) 305 EmitVLASize(Ty); 306 } 307} 308 309void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) { 310 const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl()); 311 assert(FD->getBody()); 312 EmitStmt(FD->getBody()); 313} 314 315/// Tries to mark the given function nounwind based on the 316/// non-existence of any throwing calls within it. We believe this is 317/// lightweight enough to do at -O0. 318static void TryMarkNoThrow(llvm::Function *F) { 319 // LLVM treats 'nounwind' on a function as part of the type, so we 320 // can't do this on functions that can be overwritten. 321 if (F->mayBeOverridden()) return; 322 323 for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI) 324 for (llvm::BasicBlock::iterator 325 BI = FI->begin(), BE = FI->end(); BI != BE; ++BI) 326 if (llvm::CallInst *Call = dyn_cast<llvm::CallInst>(&*BI)) 327 if (!Call->doesNotThrow()) 328 return; 329 F->setDoesNotThrow(true); 330} 331 332void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn, 333 const CGFunctionInfo &FnInfo) { 334 const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl()); 335 336 // Check if we should generate debug info for this function. 337 if (CGM.getModuleDebugInfo() && !FD->hasAttr<NoDebugAttr>()) 338 DebugInfo = CGM.getModuleDebugInfo(); 339 340 FunctionArgList Args; 341 QualType ResTy = FD->getResultType(); 342 343 CurGD = GD; 344 if (isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isInstance()) 345 CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args); 346 347 if (FD->getNumParams()) 348 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) 349 Args.push_back(FD->getParamDecl(i)); 350 351 SourceRange BodyRange; 352 if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange(); 353 354 // Emit the standard function prologue. 355 StartFunction(GD, ResTy, Fn, FnInfo, Args, BodyRange.getBegin()); 356 357 // Generate the body of the function. 358 if (isa<CXXDestructorDecl>(FD)) 359 EmitDestructorBody(Args); 360 else if (isa<CXXConstructorDecl>(FD)) 361 EmitConstructorBody(Args); 362 else 363 EmitFunctionBody(Args); 364 365 // Emit the standard function epilogue. 366 FinishFunction(BodyRange.getEnd()); 367 368 // If we haven't marked the function nothrow through other means, do 369 // a quick pass now to see if we can. 370 if (!CurFn->doesNotThrow()) 371 TryMarkNoThrow(CurFn); 372} 373 374/// ContainsLabel - Return true if the statement contains a label in it. If 375/// this statement is not executed normally, it not containing a label means 376/// that we can just remove the code. 377bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { 378 // Null statement, not a label! 379 if (S == 0) return false; 380 381 // If this is a label, we have to emit the code, consider something like: 382 // if (0) { ... foo: bar(); } goto foo; 383 // 384 // TODO: If anyone cared, we could track __label__'s, since we know that you 385 // can't jump to one from outside their declared region. 386 if (isa<LabelStmt>(S)) 387 return true; 388 389 // If this is a case/default statement, and we haven't seen a switch, we have 390 // to emit the code. 391 if (isa<SwitchCase>(S) && !IgnoreCaseStmts) 392 return true; 393 394 // If this is a switch statement, we want to ignore cases below it. 395 if (isa<SwitchStmt>(S)) 396 IgnoreCaseStmts = true; 397 398 // Scan subexpressions for verboten labels. 399 for (Stmt::const_child_range I = S->children(); I; ++I) 400 if (ContainsLabel(*I, IgnoreCaseStmts)) 401 return true; 402 403 return false; 404} 405 406/// containsBreak - Return true if the statement contains a break out of it. 407/// If the statement (recursively) contains a switch or loop with a break 408/// inside of it, this is fine. 409bool CodeGenFunction::containsBreak(const Stmt *S) { 410 // Null statement, not a label! 411 if (S == 0) return false; 412 413 // If this is a switch or loop that defines its own break scope, then we can 414 // include it and anything inside of it. 415 if (isa<SwitchStmt>(S) || isa<WhileStmt>(S) || isa<DoStmt>(S) || 416 isa<ForStmt>(S)) 417 return false; 418 419 if (isa<BreakStmt>(S)) 420 return true; 421 422 // Scan subexpressions for verboten breaks. 423 for (Stmt::const_child_range I = S->children(); I; ++I) 424 if (containsBreak(*I)) 425 return true; 426 427 return false; 428} 429 430 431/// ConstantFoldsToSimpleInteger - If the specified expression does not fold 432/// to a constant, or if it does but contains a label, return false. If it 433/// constant folds return true and set the boolean result in Result. 434bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond, 435 bool &ResultBool) { 436 llvm::APInt ResultInt; 437 if (!ConstantFoldsToSimpleInteger(Cond, ResultInt)) 438 return false; 439 440 ResultBool = ResultInt.getBoolValue(); 441 return true; 442} 443 444/// ConstantFoldsToSimpleInteger - If the specified expression does not fold 445/// to a constant, or if it does but contains a label, return false. If it 446/// constant folds return true and set the folded value. 447bool CodeGenFunction:: 448ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APInt &ResultInt) { 449 // FIXME: Rename and handle conversion of other evaluatable things 450 // to bool. 451 Expr::EvalResult Result; 452 if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() || 453 Result.HasSideEffects) 454 return false; // Not foldable, not integer or not fully evaluatable. 455 456 if (CodeGenFunction::ContainsLabel(Cond)) 457 return false; // Contains a label. 458 459 ResultInt = Result.Val.getInt(); 460 return true; 461} 462 463 464 465/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if 466/// statement) to the specified blocks. Based on the condition, this might try 467/// to simplify the codegen of the conditional based on the branch. 468/// 469void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, 470 llvm::BasicBlock *TrueBlock, 471 llvm::BasicBlock *FalseBlock) { 472 Cond = Cond->IgnoreParens(); 473 474 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { 475 // Handle X && Y in a condition. 476 if (CondBOp->getOpcode() == BO_LAnd) { 477 // If we have "1 && X", simplify the code. "0 && X" would have constant 478 // folded if the case was simple enough. 479 bool ConstantBool = false; 480 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) && 481 ConstantBool) { 482 // br(1 && X) -> br(X). 483 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 484 } 485 486 // If we have "X && 1", simplify the code to use an uncond branch. 487 // "X && 0" would have been constant folded to 0. 488 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) && 489 ConstantBool) { 490 // br(X && 1) -> br(X). 491 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 492 } 493 494 // Emit the LHS as a conditional. If the LHS conditional is false, we 495 // want to jump to the FalseBlock. 496 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); 497 498 ConditionalEvaluation eval(*this); 499 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); 500 EmitBlock(LHSTrue); 501 502 // Any temporaries created here are conditional. 503 eval.begin(*this); 504 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 505 eval.end(*this); 506 507 return; 508 } 509 510 if (CondBOp->getOpcode() == BO_LOr) { 511 // If we have "0 || X", simplify the code. "1 || X" would have constant 512 // folded if the case was simple enough. 513 bool ConstantBool = false; 514 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) && 515 !ConstantBool) { 516 // br(0 || X) -> br(X). 517 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 518 } 519 520 // If we have "X || 0", simplify the code to use an uncond branch. 521 // "X || 1" would have been constant folded to 1. 522 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) && 523 !ConstantBool) { 524 // br(X || 0) -> br(X). 525 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 526 } 527 528 // Emit the LHS as a conditional. If the LHS conditional is true, we 529 // want to jump to the TrueBlock. 530 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); 531 532 ConditionalEvaluation eval(*this); 533 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); 534 EmitBlock(LHSFalse); 535 536 // Any temporaries created here are conditional. 537 eval.begin(*this); 538 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 539 eval.end(*this); 540 541 return; 542 } 543 } 544 545 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { 546 // br(!x, t, f) -> br(x, f, t) 547 if (CondUOp->getOpcode() == UO_LNot) 548 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); 549 } 550 551 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) { 552 // Handle ?: operator. 553 554 // Just ignore GNU ?: extension. 555 if (CondOp->getLHS()) { 556 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) 557 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); 558 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); 559 560 ConditionalEvaluation cond(*this); 561 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); 562 563 cond.begin(*this); 564 EmitBlock(LHSBlock); 565 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); 566 cond.end(*this); 567 568 cond.begin(*this); 569 EmitBlock(RHSBlock); 570 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); 571 cond.end(*this); 572 573 return; 574 } 575 } 576 577 // Emit the code with the fully general case. 578 llvm::Value *CondV = EvaluateExprAsBool(Cond); 579 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); 580} 581 582/// ErrorUnsupported - Print out an error that codegen doesn't support the 583/// specified stmt yet. 584void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, 585 bool OmitOnError) { 586 CGM.ErrorUnsupported(S, Type, OmitOnError); 587} 588 589/// emitNonZeroVLAInit - Emit the "zero" initialization of a 590/// variable-length array whose elements have a non-zero bit-pattern. 591/// 592/// \param src - a char* pointing to the bit-pattern for a single 593/// base element of the array 594/// \param sizeInChars - the total size of the VLA, in chars 595/// \param align - the total alignment of the VLA 596static void emitNonZeroVLAInit(CodeGenFunction &CGF, QualType baseType, 597 llvm::Value *dest, llvm::Value *src, 598 llvm::Value *sizeInChars) { 599 std::pair<CharUnits,CharUnits> baseSizeAndAlign 600 = CGF.getContext().getTypeInfoInChars(baseType); 601 602 CGBuilderTy &Builder = CGF.Builder; 603 604 llvm::Value *baseSizeInChars 605 = llvm::ConstantInt::get(CGF.IntPtrTy, baseSizeAndAlign.first.getQuantity()); 606 607 const llvm::Type *i8p = Builder.getInt8PtrTy(); 608 609 llvm::Value *begin = Builder.CreateBitCast(dest, i8p, "vla.begin"); 610 llvm::Value *end = Builder.CreateInBoundsGEP(dest, sizeInChars, "vla.end"); 611 612 llvm::BasicBlock *originBB = CGF.Builder.GetInsertBlock(); 613 llvm::BasicBlock *loopBB = CGF.createBasicBlock("vla-init.loop"); 614 llvm::BasicBlock *contBB = CGF.createBasicBlock("vla-init.cont"); 615 616 // Make a loop over the VLA. C99 guarantees that the VLA element 617 // count must be nonzero. 618 CGF.EmitBlock(loopBB); 619 620 llvm::PHINode *cur = Builder.CreatePHI(i8p, 2, "vla.cur"); 621 cur->addIncoming(begin, originBB); 622 623 // memcpy the individual element bit-pattern. 624 Builder.CreateMemCpy(cur, src, baseSizeInChars, 625 baseSizeAndAlign.second.getQuantity(), 626 /*volatile*/ false); 627 628 // Go to the next element. 629 llvm::Value *next = Builder.CreateConstInBoundsGEP1_32(cur, 1, "vla.next"); 630 631 // Leave if that's the end of the VLA. 632 llvm::Value *done = Builder.CreateICmpEQ(next, end, "vla-init.isdone"); 633 Builder.CreateCondBr(done, contBB, loopBB); 634 cur->addIncoming(next, loopBB); 635 636 CGF.EmitBlock(contBB); 637} 638 639void 640CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) { 641 // Ignore empty classes in C++. 642 if (getContext().getLangOptions().CPlusPlus) { 643 if (const RecordType *RT = Ty->getAs<RecordType>()) { 644 if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty()) 645 return; 646 } 647 } 648 649 // Cast the dest ptr to the appropriate i8 pointer type. 650 unsigned DestAS = 651 cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace(); 652 const llvm::Type *BP = Builder.getInt8PtrTy(DestAS); 653 if (DestPtr->getType() != BP) 654 DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); 655 656 // Get size and alignment info for this aggregate. 657 std::pair<CharUnits, CharUnits> TypeInfo = 658 getContext().getTypeInfoInChars(Ty); 659 CharUnits Size = TypeInfo.first; 660 CharUnits Align = TypeInfo.second; 661 662 llvm::Value *SizeVal; 663 const VariableArrayType *vla; 664 665 // Don't bother emitting a zero-byte memset. 666 if (Size.isZero()) { 667 // But note that getTypeInfo returns 0 for a VLA. 668 if (const VariableArrayType *vlaType = 669 dyn_cast_or_null<VariableArrayType>( 670 getContext().getAsArrayType(Ty))) { 671 SizeVal = GetVLASize(vlaType); 672 vla = vlaType; 673 } else { 674 return; 675 } 676 } else { 677 SizeVal = llvm::ConstantInt::get(IntPtrTy, Size.getQuantity()); 678 vla = 0; 679 } 680 681 // If the type contains a pointer to data member we can't memset it to zero. 682 // Instead, create a null constant and copy it to the destination. 683 // TODO: there are other patterns besides zero that we can usefully memset, 684 // like -1, which happens to be the pattern used by member-pointers. 685 if (!CGM.getTypes().isZeroInitializable(Ty)) { 686 // For a VLA, emit a single element, then splat that over the VLA. 687 if (vla) Ty = getContext().getBaseElementType(vla); 688 689 llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty); 690 691 llvm::GlobalVariable *NullVariable = 692 new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(), 693 /*isConstant=*/true, 694 llvm::GlobalVariable::PrivateLinkage, 695 NullConstant, llvm::Twine()); 696 llvm::Value *SrcPtr = 697 Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy()); 698 699 if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal); 700 701 // Get and call the appropriate llvm.memcpy overload. 702 Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align.getQuantity(), false); 703 return; 704 } 705 706 // Otherwise, just memset the whole thing to zero. This is legal 707 // because in LLVM, all default initializers (other than the ones we just 708 // handled above) are guaranteed to have a bit pattern of all zeros. 709 Builder.CreateMemSet(DestPtr, Builder.getInt8(0), SizeVal, 710 Align.getQuantity(), false); 711} 712 713llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *L) { 714 // Make sure that there is a block for the indirect goto. 715 if (IndirectBranch == 0) 716 GetIndirectGotoBlock(); 717 718 llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock(); 719 720 // Make sure the indirect branch includes all of the address-taken blocks. 721 IndirectBranch->addDestination(BB); 722 return llvm::BlockAddress::get(CurFn, BB); 723} 724 725llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() { 726 // If we already made the indirect branch for indirect goto, return its block. 727 if (IndirectBranch) return IndirectBranch->getParent(); 728 729 CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto")); 730 731 // Create the PHI node that indirect gotos will add entries to. 732 llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, 0, 733 "indirect.goto.dest"); 734 735 // Create the indirect branch instruction. 736 IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal); 737 return IndirectBranch->getParent(); 738} 739 740llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) { 741 llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; 742 743 assert(SizeEntry && "Did not emit size for type"); 744 return SizeEntry; 745} 746 747llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) { 748 assert(Ty->isVariablyModifiedType() && 749 "Must pass variably modified type to EmitVLASizes!"); 750 751 EnsureInsertPoint(); 752 753 if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) { 754 // unknown size indication requires no size computation. 755 if (!VAT->getSizeExpr()) 756 return 0; 757 llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; 758 759 if (!SizeEntry) { 760 const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); 761 762 // Get the element size; 763 QualType ElemTy = VAT->getElementType(); 764 llvm::Value *ElemSize; 765 if (ElemTy->isVariableArrayType()) 766 ElemSize = EmitVLASize(ElemTy); 767 else 768 ElemSize = llvm::ConstantInt::get(SizeTy, 769 getContext().getTypeSizeInChars(ElemTy).getQuantity()); 770 771 llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr()); 772 NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp"); 773 774 SizeEntry = Builder.CreateMul(ElemSize, NumElements); 775 } 776 777 return SizeEntry; 778 } 779 780 if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) { 781 EmitVLASize(AT->getElementType()); 782 return 0; 783 } 784 785 if (const ParenType *PT = dyn_cast<ParenType>(Ty)) { 786 EmitVLASize(PT->getInnerType()); 787 return 0; 788 } 789 790 const PointerType *PT = Ty->getAs<PointerType>(); 791 assert(PT && "unknown VM type!"); 792 EmitVLASize(PT->getPointeeType()); 793 return 0; 794} 795 796llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { 797 if (getContext().getBuiltinVaListType()->isArrayType()) 798 return EmitScalarExpr(E); 799 return EmitLValue(E).getAddress(); 800} 801 802void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E, 803 llvm::Constant *Init) { 804 assert (Init && "Invalid DeclRefExpr initializer!"); 805 if (CGDebugInfo *Dbg = getDebugInfo()) 806 Dbg->EmitGlobalVariable(E->getDecl(), Init); 807} 808 809CodeGenFunction::PeepholeProtection 810CodeGenFunction::protectFromPeepholes(RValue rvalue) { 811 // At the moment, the only aggressive peephole we do in IR gen 812 // is trunc(zext) folding, but if we add more, we can easily 813 // extend this protection. 814 815 if (!rvalue.isScalar()) return PeepholeProtection(); 816 llvm::Value *value = rvalue.getScalarVal(); 817 if (!isa<llvm::ZExtInst>(value)) return PeepholeProtection(); 818 819 // Just make an extra bitcast. 820 assert(HaveInsertPoint()); 821 llvm::Instruction *inst = new llvm::BitCastInst(value, value->getType(), "", 822 Builder.GetInsertBlock()); 823 824 PeepholeProtection protection; 825 protection.Inst = inst; 826 return protection; 827} 828 829void CodeGenFunction::unprotectFromPeepholes(PeepholeProtection protection) { 830 if (!protection.Inst) return; 831 832 // In theory, we could try to duplicate the peepholes now, but whatever. 833 protection.Inst->eraseFromParent(); 834} 835