CodeGenFunction.cpp revision 88d117c2eedd7c5bec57ac983a98d5e12bdd2cc6
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), 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 FunctionArgList &Args, 214 SourceLocation StartLoc, 215 CallingConv CC) { 216 const Decl *D = GD.getDecl(); 217 218 DidCallStackSave = false; 219 CurCodeDecl = CurFuncDecl = D; 220 FnRetTy = RetTy; 221 CurFn = Fn; 222 assert(CurFn->isDeclaration() && "Function already has body?"); 223 224 // Pass inline keyword to optimizer if it appears explicitly on any 225 // declaration. 226 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) 227 for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(), 228 RE = FD->redecls_end(); RI != RE; ++RI) 229 if (RI->isInlineSpecified()) { 230 Fn->addFnAttr(llvm::Attribute::InlineHint); 231 break; 232 } 233 234 if (getContext().getLangOptions().OpenCL) { 235 // Add metadata for a kernel function. 236 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) 237 if (FD->hasAttr<OpenCLKernelAttr>()) { 238 llvm::LLVMContext &Context = getLLVMContext(); 239 llvm::NamedMDNode *OpenCLMetadata = 240 CGM.getModule().getOrInsertNamedMetadata("opencl.kernels"); 241 242 llvm::Value *Op = Fn; 243 OpenCLMetadata->addOperand(llvm::MDNode::get(Context, &Op, 1)); 244 } 245 } 246 247 llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn); 248 249 // Create a marker to make it easy to insert allocas into the entryblock 250 // later. Don't create this with the builder, because we don't want it 251 // folded. 252 llvm::Value *Undef = llvm::UndefValue::get(Int32Ty); 253 AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB); 254 if (Builder.isNamePreserving()) 255 AllocaInsertPt->setName("allocapt"); 256 257 ReturnBlock = getJumpDestInCurrentScope("return"); 258 259 Builder.SetInsertPoint(EntryBB); 260 261 // Emit subprogram debug descriptor. 262 if (CGDebugInfo *DI = getDebugInfo()) { 263 // FIXME: what is going on here and why does it ignore all these 264 // interesting type properties? 265 QualType FnType = 266 getContext().getFunctionType(RetTy, 0, 0, 267 FunctionProtoType::ExtProtoInfo()); 268 269 DI->setLocation(StartLoc); 270 DI->EmitFunctionStart(GD, FnType, CurFn, Builder); 271 } 272 273 if (ShouldInstrumentFunction()) 274 EmitFunctionInstrumentation("__cyg_profile_func_enter"); 275 276 if (CGM.getCodeGenOpts().InstrumentForProfiling) 277 EmitMCountInstrumentation(); 278 279 // FIXME: Leaked. 280 // CC info is ignored, hopefully? 281 CurFnInfo = &CGM.getTypes().getFunctionInfo(FnRetTy, Args, 282 FunctionType::ExtInfo().withCallingConv(CC)); 283 284 if (RetTy->isVoidType()) { 285 // Void type; nothing to return. 286 ReturnValue = 0; 287 } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect && 288 hasAggregateLLVMType(CurFnInfo->getReturnType())) { 289 // Indirect aggregate return; emit returned value directly into sret slot. 290 // This reduces code size, and affects correctness in C++. 291 ReturnValue = CurFn->arg_begin(); 292 } else { 293 ReturnValue = CreateIRTemp(RetTy, "retval"); 294 } 295 296 EmitStartEHSpec(CurCodeDecl); 297 EmitFunctionProlog(*CurFnInfo, CurFn, Args); 298 299 if (D && isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance()) 300 CGM.getCXXABI().EmitInstanceFunctionProlog(*this); 301 302 // If any of the arguments have a variably modified type, make sure to 303 // emit the type size. 304 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); 305 i != e; ++i) { 306 QualType Ty = i->second; 307 308 if (Ty->isVariablyModifiedType()) 309 EmitVLASize(Ty); 310 } 311} 312 313void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) { 314 const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl()); 315 assert(FD->getBody()); 316 EmitStmt(FD->getBody()); 317} 318 319/// Tries to mark the given function nounwind based on the 320/// non-existence of any throwing calls within it. We believe this is 321/// lightweight enough to do at -O0. 322static void TryMarkNoThrow(llvm::Function *F) { 323 // LLVM treats 'nounwind' on a function as part of the type, so we 324 // can't do this on functions that can be overwritten. 325 if (F->mayBeOverridden()) return; 326 327 for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI) 328 for (llvm::BasicBlock::iterator 329 BI = FI->begin(), BE = FI->end(); BI != BE; ++BI) 330 if (llvm::CallInst *Call = dyn_cast<llvm::CallInst>(&*BI)) 331 if (!Call->doesNotThrow()) 332 return; 333 F->setDoesNotThrow(true); 334} 335 336void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn) { 337 const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl()); 338 339 // Check if we should generate debug info for this function. 340 if (CGM.getDebugInfo() && !FD->hasAttr<NoDebugAttr>()) 341 DebugInfo = CGM.getDebugInfo(); 342 343 FunctionArgList Args; 344 QualType ResTy = FD->getResultType(); 345 346 CurGD = GD; 347 if (isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isInstance()) 348 CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args); 349 350 if (FD->getNumParams()) { 351 const FunctionProtoType* FProto = FD->getType()->getAs<FunctionProtoType>(); 352 assert(FProto && "Function def must have prototype!"); 353 354 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) 355 Args.push_back(std::make_pair(FD->getParamDecl(i), 356 FProto->getArgType(i))); 357 } 358 359 SourceRange BodyRange; 360 if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange(); 361 362 // Emit the standard function prologue. 363 StartFunction(GD, ResTy, Fn, Args, BodyRange.getBegin(), CC_Default); 364 365 // Generate the body of the function. 366 if (isa<CXXDestructorDecl>(FD)) 367 EmitDestructorBody(Args); 368 else if (isa<CXXConstructorDecl>(FD)) 369 EmitConstructorBody(Args); 370 else 371 EmitFunctionBody(Args); 372 373 // Emit the standard function epilogue. 374 FinishFunction(BodyRange.getEnd()); 375 376 // If we haven't marked the function nothrow through other means, do 377 // a quick pass now to see if we can. 378 if (!CurFn->doesNotThrow()) 379 TryMarkNoThrow(CurFn); 380} 381 382/// ContainsLabel - Return true if the statement contains a label in it. If 383/// this statement is not executed normally, it not containing a label means 384/// that we can just remove the code. 385bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { 386 // Null statement, not a label! 387 if (S == 0) return false; 388 389 // If this is a label, we have to emit the code, consider something like: 390 // if (0) { ... foo: bar(); } goto foo; 391 // 392 // TODO: If anyone cared, we could track __label__'s, since we know that you 393 // can't jump to one from outside their declared region. 394 if (isa<LabelStmt>(S)) 395 return true; 396 397 // If this is a case/default statement, and we haven't seen a switch, we have 398 // to emit the code. 399 if (isa<SwitchCase>(S) && !IgnoreCaseStmts) 400 return true; 401 402 // If this is a switch statement, we want to ignore cases below it. 403 if (isa<SwitchStmt>(S)) 404 IgnoreCaseStmts = true; 405 406 // Scan subexpressions for verboten labels. 407 for (Stmt::const_child_range I = S->children(); I; ++I) 408 if (ContainsLabel(*I, IgnoreCaseStmts)) 409 return true; 410 411 return false; 412} 413 414/// containsBreak - Return true if the statement contains a break out of it. 415/// If the statement (recursively) contains a switch or loop with a break 416/// inside of it, this is fine. 417bool CodeGenFunction::containsBreak(const Stmt *S) { 418 // Null statement, not a label! 419 if (S == 0) return false; 420 421 // If this is a switch or loop that defines its own break scope, then we can 422 // include it and anything inside of it. 423 if (isa<SwitchStmt>(S) || isa<WhileStmt>(S) || isa<DoStmt>(S) || 424 isa<ForStmt>(S)) 425 return false; 426 427 if (isa<BreakStmt>(S)) 428 return true; 429 430 // Scan subexpressions for verboten breaks. 431 for (Stmt::const_child_range I = S->children(); I; ++I) 432 if (containsBreak(*I)) 433 return true; 434 435 return false; 436} 437 438 439/// ConstantFoldsToSimpleInteger - If the specified expression does not fold 440/// to a constant, or if it does but contains a label, return false. If it 441/// constant folds return true and set the boolean result in Result. 442bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond, 443 bool &ResultBool) { 444 llvm::APInt ResultInt; 445 if (!ConstantFoldsToSimpleInteger(Cond, ResultInt)) 446 return false; 447 448 ResultBool = ResultInt.getBoolValue(); 449 return true; 450} 451 452/// ConstantFoldsToSimpleInteger - If the specified expression does not fold 453/// to a constant, or if it does but contains a label, return false. If it 454/// constant folds return true and set the folded value. 455bool CodeGenFunction:: 456ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APInt &ResultInt) { 457 // FIXME: Rename and handle conversion of other evaluatable things 458 // to bool. 459 Expr::EvalResult Result; 460 if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() || 461 Result.HasSideEffects) 462 return false; // Not foldable, not integer or not fully evaluatable. 463 464 if (CodeGenFunction::ContainsLabel(Cond)) 465 return false; // Contains a label. 466 467 ResultInt = Result.Val.getInt(); 468 return true; 469} 470 471 472 473/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if 474/// statement) to the specified blocks. Based on the condition, this might try 475/// to simplify the codegen of the conditional based on the branch. 476/// 477void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, 478 llvm::BasicBlock *TrueBlock, 479 llvm::BasicBlock *FalseBlock) { 480 if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) 481 return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock); 482 483 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { 484 // Handle X && Y in a condition. 485 if (CondBOp->getOpcode() == BO_LAnd) { 486 // If we have "1 && X", simplify the code. "0 && X" would have constant 487 // folded if the case was simple enough. 488 bool ConstantBool; 489 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) && 490 ConstantBool) { 491 // br(1 && X) -> br(X). 492 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 493 } 494 495 // If we have "X && 1", simplify the code to use an uncond branch. 496 // "X && 0" would have been constant folded to 0. 497 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) && 498 ConstantBool) { 499 // br(X && 1) -> br(X). 500 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 501 } 502 503 // Emit the LHS as a conditional. If the LHS conditional is false, we 504 // want to jump to the FalseBlock. 505 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); 506 507 ConditionalEvaluation eval(*this); 508 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); 509 EmitBlock(LHSTrue); 510 511 // Any temporaries created here are conditional. 512 eval.begin(*this); 513 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 514 eval.end(*this); 515 516 return; 517 } 518 519 if (CondBOp->getOpcode() == BO_LOr) { 520 // If we have "0 || X", simplify the code. "1 || X" would have constant 521 // folded if the case was simple enough. 522 bool ConstantBool; 523 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) && 524 !ConstantBool) { 525 // br(0 || X) -> br(X). 526 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 527 } 528 529 // If we have "X || 0", simplify the code to use an uncond branch. 530 // "X || 1" would have been constant folded to 1. 531 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) && 532 !ConstantBool) { 533 // br(X || 0) -> br(X). 534 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 535 } 536 537 // Emit the LHS as a conditional. If the LHS conditional is true, we 538 // want to jump to the TrueBlock. 539 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); 540 541 ConditionalEvaluation eval(*this); 542 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); 543 EmitBlock(LHSFalse); 544 545 // Any temporaries created here are conditional. 546 eval.begin(*this); 547 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 548 eval.end(*this); 549 550 return; 551 } 552 } 553 554 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { 555 // br(!x, t, f) -> br(x, f, t) 556 if (CondUOp->getOpcode() == UO_LNot) 557 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); 558 } 559 560 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) { 561 // Handle ?: operator. 562 563 // Just ignore GNU ?: extension. 564 if (CondOp->getLHS()) { 565 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) 566 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); 567 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); 568 569 ConditionalEvaluation cond(*this); 570 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); 571 572 cond.begin(*this); 573 EmitBlock(LHSBlock); 574 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); 575 cond.end(*this); 576 577 cond.begin(*this); 578 EmitBlock(RHSBlock); 579 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); 580 cond.end(*this); 581 582 return; 583 } 584 } 585 586 // Emit the code with the fully general case. 587 llvm::Value *CondV = EvaluateExprAsBool(Cond); 588 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); 589} 590 591/// ErrorUnsupported - Print out an error that codegen doesn't support the 592/// specified stmt yet. 593void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, 594 bool OmitOnError) { 595 CGM.ErrorUnsupported(S, Type, OmitOnError); 596} 597 598/// emitNonZeroVLAInit - Emit the "zero" initialization of a 599/// variable-length array whose elements have a non-zero bit-pattern. 600/// 601/// \param src - a char* pointing to the bit-pattern for a single 602/// base element of the array 603/// \param sizeInChars - the total size of the VLA, in chars 604/// \param align - the total alignment of the VLA 605static void emitNonZeroVLAInit(CodeGenFunction &CGF, QualType baseType, 606 llvm::Value *dest, llvm::Value *src, 607 llvm::Value *sizeInChars) { 608 std::pair<CharUnits,CharUnits> baseSizeAndAlign 609 = CGF.getContext().getTypeInfoInChars(baseType); 610 611 CGBuilderTy &Builder = CGF.Builder; 612 613 llvm::Value *baseSizeInChars 614 = llvm::ConstantInt::get(CGF.IntPtrTy, baseSizeAndAlign.first.getQuantity()); 615 616 const llvm::Type *i8p = Builder.getInt8PtrTy(); 617 618 llvm::Value *begin = Builder.CreateBitCast(dest, i8p, "vla.begin"); 619 llvm::Value *end = Builder.CreateInBoundsGEP(dest, sizeInChars, "vla.end"); 620 621 llvm::BasicBlock *originBB = CGF.Builder.GetInsertBlock(); 622 llvm::BasicBlock *loopBB = CGF.createBasicBlock("vla-init.loop"); 623 llvm::BasicBlock *contBB = CGF.createBasicBlock("vla-init.cont"); 624 625 // Make a loop over the VLA. C99 guarantees that the VLA element 626 // count must be nonzero. 627 CGF.EmitBlock(loopBB); 628 629 llvm::PHINode *cur = Builder.CreatePHI(i8p, "vla.cur"); 630 cur->reserveOperandSpace(2); 631 cur->addIncoming(begin, originBB); 632 633 // memcpy the individual element bit-pattern. 634 Builder.CreateMemCpy(cur, src, baseSizeInChars, 635 baseSizeAndAlign.second.getQuantity(), 636 /*volatile*/ false); 637 638 // Go to the next element. 639 llvm::Value *next = Builder.CreateConstInBoundsGEP1_32(cur, 1, "vla.next"); 640 641 // Leave if that's the end of the VLA. 642 llvm::Value *done = Builder.CreateICmpEQ(next, end, "vla-init.isdone"); 643 Builder.CreateCondBr(done, contBB, loopBB); 644 cur->addIncoming(next, loopBB); 645 646 CGF.EmitBlock(contBB); 647} 648 649void 650CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) { 651 // Ignore empty classes in C++. 652 if (getContext().getLangOptions().CPlusPlus) { 653 if (const RecordType *RT = Ty->getAs<RecordType>()) { 654 if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty()) 655 return; 656 } 657 } 658 659 // Cast the dest ptr to the appropriate i8 pointer type. 660 unsigned DestAS = 661 cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace(); 662 const llvm::Type *BP = Builder.getInt8PtrTy(DestAS); 663 if (DestPtr->getType() != BP) 664 DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); 665 666 // Get size and alignment info for this aggregate. 667 std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); 668 uint64_t Size = TypeInfo.first / 8; 669 unsigned Align = TypeInfo.second / 8; 670 671 llvm::Value *SizeVal; 672 const VariableArrayType *vla; 673 674 // Don't bother emitting a zero-byte memset. 675 if (Size == 0) { 676 // But note that getTypeInfo returns 0 for a VLA. 677 if (const VariableArrayType *vlaType = 678 dyn_cast_or_null<VariableArrayType>( 679 getContext().getAsArrayType(Ty))) { 680 SizeVal = GetVLASize(vlaType); 681 vla = vlaType; 682 } else { 683 return; 684 } 685 } else { 686 SizeVal = llvm::ConstantInt::get(IntPtrTy, Size); 687 vla = 0; 688 } 689 690 // If the type contains a pointer to data member we can't memset it to zero. 691 // Instead, create a null constant and copy it to the destination. 692 // TODO: there are other patterns besides zero that we can usefully memset, 693 // like -1, which happens to be the pattern used by member-pointers. 694 if (!CGM.getTypes().isZeroInitializable(Ty)) { 695 // For a VLA, emit a single element, then splat that over the VLA. 696 if (vla) Ty = getContext().getBaseElementType(vla); 697 698 llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty); 699 700 llvm::GlobalVariable *NullVariable = 701 new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(), 702 /*isConstant=*/true, 703 llvm::GlobalVariable::PrivateLinkage, 704 NullConstant, llvm::Twine()); 705 llvm::Value *SrcPtr = 706 Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy()); 707 708 if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal); 709 710 // Get and call the appropriate llvm.memcpy overload. 711 Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align, false); 712 return; 713 } 714 715 // Otherwise, just memset the whole thing to zero. This is legal 716 // because in LLVM, all default initializers (other than the ones we just 717 // handled above) are guaranteed to have a bit pattern of all zeros. 718 Builder.CreateMemSet(DestPtr, Builder.getInt8(0), SizeVal, Align, false); 719} 720 721llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *L) { 722 // Make sure that there is a block for the indirect goto. 723 if (IndirectBranch == 0) 724 GetIndirectGotoBlock(); 725 726 llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock(); 727 728 // Make sure the indirect branch includes all of the address-taken blocks. 729 IndirectBranch->addDestination(BB); 730 return llvm::BlockAddress::get(CurFn, BB); 731} 732 733llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() { 734 // If we already made the indirect branch for indirect goto, return its block. 735 if (IndirectBranch) return IndirectBranch->getParent(); 736 737 CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto")); 738 739 // Create the PHI node that indirect gotos will add entries to. 740 llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, "indirect.goto.dest"); 741 742 // Create the indirect branch instruction. 743 IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal); 744 return IndirectBranch->getParent(); 745} 746 747llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) { 748 llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; 749 750 assert(SizeEntry && "Did not emit size for type"); 751 return SizeEntry; 752} 753 754llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) { 755 assert(Ty->isVariablyModifiedType() && 756 "Must pass variably modified type to EmitVLASizes!"); 757 758 EnsureInsertPoint(); 759 760 if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) { 761 // unknown size indication requires no size computation. 762 if (!VAT->getSizeExpr()) 763 return 0; 764 llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; 765 766 if (!SizeEntry) { 767 const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); 768 769 // Get the element size; 770 QualType ElemTy = VAT->getElementType(); 771 llvm::Value *ElemSize; 772 if (ElemTy->isVariableArrayType()) 773 ElemSize = EmitVLASize(ElemTy); 774 else 775 ElemSize = llvm::ConstantInt::get(SizeTy, 776 getContext().getTypeSizeInChars(ElemTy).getQuantity()); 777 778 llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr()); 779 NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp"); 780 781 SizeEntry = Builder.CreateMul(ElemSize, NumElements); 782 } 783 784 return SizeEntry; 785 } 786 787 if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) { 788 EmitVLASize(AT->getElementType()); 789 return 0; 790 } 791 792 if (const ParenType *PT = dyn_cast<ParenType>(Ty)) { 793 EmitVLASize(PT->getInnerType()); 794 return 0; 795 } 796 797 const PointerType *PT = Ty->getAs<PointerType>(); 798 assert(PT && "unknown VM type!"); 799 EmitVLASize(PT->getPointeeType()); 800 return 0; 801} 802 803llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { 804 if (getContext().getBuiltinVaListType()->isArrayType()) 805 return EmitScalarExpr(E); 806 return EmitLValue(E).getAddress(); 807} 808 809void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E, 810 llvm::Constant *Init) { 811 assert (Init && "Invalid DeclRefExpr initializer!"); 812 if (CGDebugInfo *Dbg = getDebugInfo()) 813 Dbg->EmitGlobalVariable(E->getDecl(), Init); 814} 815 816CodeGenFunction::PeepholeProtection 817CodeGenFunction::protectFromPeepholes(RValue rvalue) { 818 // At the moment, the only aggressive peephole we do in IR gen 819 // is trunc(zext) folding, but if we add more, we can easily 820 // extend this protection. 821 822 if (!rvalue.isScalar()) return PeepholeProtection(); 823 llvm::Value *value = rvalue.getScalarVal(); 824 if (!isa<llvm::ZExtInst>(value)) return PeepholeProtection(); 825 826 // Just make an extra bitcast. 827 assert(HaveInsertPoint()); 828 llvm::Instruction *inst = new llvm::BitCastInst(value, value->getType(), "", 829 Builder.GetInsertBlock()); 830 831 PeepholeProtection protection; 832 protection.Inst = inst; 833 return protection; 834} 835 836void CodeGenFunction::unprotectFromPeepholes(PeepholeProtection protection) { 837 if (!protection.Inst) return; 838 839 // In theory, we could try to duplicate the peepholes now, but whatever. 840 protection.Inst->eraseFromParent(); 841} 842