//===--- CodeGenFunction.cpp - Emit LLVM Code from ASTs for a Function ----===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This coordinates the per-function state used while generating code. // //===----------------------------------------------------------------------===// #include "CodeGenFunction.h" #include "CodeGenModule.h" #include "CGCXXABI.h" #include "CGDebugInfo.h" #include "CGException.h" #include "clang/Basic/TargetInfo.h" #include "clang/AST/APValue.h" #include "clang/AST/ASTContext.h" #include "clang/AST/Decl.h" #include "clang/AST/DeclCXX.h" #include "clang/AST/StmtCXX.h" #include "clang/Frontend/CodeGenOptions.h" #include "llvm/Target/TargetData.h" #include "llvm/Intrinsics.h" using namespace clang; using namespace CodeGen; CodeGenFunction::CodeGenFunction(CodeGenModule &cgm) : CodeGenTypeCache(cgm), CGM(cgm), Target(CGM.getContext().getTargetInfo()), Builder(cgm.getModule().getContext()), AutoreleaseResult(false), BlockInfo(0), BlockPointer(0), NormalCleanupDest(0), NextCleanupDestIndex(1), EHResumeBlock(0), ExceptionSlot(0), EHSelectorSlot(0), DebugInfo(0), DisableDebugInfo(false), DidCallStackSave(false), IndirectBranch(0), SwitchInsn(0), CaseRangeBlock(0), UnreachableBlock(0), CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0), OutermostConditional(0), TerminateLandingPad(0), TerminateHandler(0), TrapBB(0) { CatchUndefined = getContext().getLangOptions().CatchUndefined; CGM.getCXXABI().getMangleContext().startNewFunction(); } llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) { return CGM.getTypes().ConvertTypeForMem(T); } llvm::Type *CodeGenFunction::ConvertType(QualType T) { return CGM.getTypes().ConvertType(T); } bool CodeGenFunction::hasAggregateLLVMType(QualType type) { switch (type.getCanonicalType()->getTypeClass()) { #define TYPE(name, parent) #define ABSTRACT_TYPE(name, parent) #define NON_CANONICAL_TYPE(name, parent) case Type::name: #define DEPENDENT_TYPE(name, parent) case Type::name: #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(name, parent) case Type::name: #include "clang/AST/TypeNodes.def" llvm_unreachable("non-canonical or dependent type in IR-generation"); case Type::Builtin: case Type::Pointer: case Type::BlockPointer: case Type::LValueReference: case Type::RValueReference: case Type::MemberPointer: case Type::Vector: case Type::ExtVector: case Type::FunctionProto: case Type::FunctionNoProto: case Type::Enum: case Type::ObjCObjectPointer: return false; // Complexes, arrays, records, and Objective-C objects. case Type::Complex: case Type::ConstantArray: case Type::IncompleteArray: case Type::VariableArray: case Type::Record: case Type::ObjCObject: case Type::ObjCInterface: return true; } llvm_unreachable("unknown type kind!"); } void CodeGenFunction::EmitReturnBlock() { // For cleanliness, we try to avoid emitting the return block for // simple cases. llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); if (CurBB) { assert(!CurBB->getTerminator() && "Unexpected terminated block."); // We have a valid insert point, reuse it if it is empty or there are no // explicit jumps to the return block. if (CurBB->empty() || ReturnBlock.getBlock()->use_empty()) { ReturnBlock.getBlock()->replaceAllUsesWith(CurBB); delete ReturnBlock.getBlock(); } else EmitBlock(ReturnBlock.getBlock()); return; } // Otherwise, if the return block is the target of a single direct // branch then we can just put the code in that block instead. This // cleans up functions which started with a unified return block. if (ReturnBlock.getBlock()->hasOneUse()) { llvm::BranchInst *BI = dyn_cast(*ReturnBlock.getBlock()->use_begin()); if (BI && BI->isUnconditional() && BI->getSuccessor(0) == ReturnBlock.getBlock()) { // Reset insertion point, including debug location, and delete the branch. Builder.SetCurrentDebugLocation(BI->getDebugLoc()); Builder.SetInsertPoint(BI->getParent()); BI->eraseFromParent(); delete ReturnBlock.getBlock(); return; } } // FIXME: We are at an unreachable point, there is no reason to emit the block // unless it has uses. However, we still need a place to put the debug // region.end for now. EmitBlock(ReturnBlock.getBlock()); } static void EmitIfUsed(CodeGenFunction &CGF, llvm::BasicBlock *BB) { if (!BB) return; if (!BB->use_empty()) return CGF.CurFn->getBasicBlockList().push_back(BB); delete BB; } void CodeGenFunction::FinishFunction(SourceLocation EndLoc) { assert(BreakContinueStack.empty() && "mismatched push/pop in break/continue stack!"); // Pop any cleanups that might have been associated with the // parameters. Do this in whatever block we're currently in; it's // important to do this before we enter the return block or return // edges will be *really* confused. if (EHStack.stable_begin() != PrologueCleanupDepth) PopCleanupBlocks(PrologueCleanupDepth); // Emit function epilog (to return). EmitReturnBlock(); if (ShouldInstrumentFunction()) EmitFunctionInstrumentation("__cyg_profile_func_exit"); // Emit debug descriptor for function end. if (CGDebugInfo *DI = getDebugInfo()) { DI->setLocation(EndLoc); DI->EmitFunctionEnd(Builder); } EmitFunctionEpilog(*CurFnInfo); EmitEndEHSpec(CurCodeDecl); assert(EHStack.empty() && "did not remove all scopes from cleanup stack!"); // If someone did an indirect goto, emit the indirect goto block at the end of // the function. if (IndirectBranch) { EmitBlock(IndirectBranch->getParent()); Builder.ClearInsertionPoint(); } // Remove the AllocaInsertPt instruction, which is just a convenience for us. llvm::Instruction *Ptr = AllocaInsertPt; AllocaInsertPt = 0; Ptr->eraseFromParent(); // If someone took the address of a label but never did an indirect goto, we // made a zero entry PHI node, which is illegal, zap it now. if (IndirectBranch) { llvm::PHINode *PN = cast(IndirectBranch->getAddress()); if (PN->getNumIncomingValues() == 0) { PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType())); PN->eraseFromParent(); } } EmitIfUsed(*this, EHResumeBlock); EmitIfUsed(*this, TerminateLandingPad); EmitIfUsed(*this, TerminateHandler); EmitIfUsed(*this, UnreachableBlock); if (CGM.getCodeGenOpts().EmitDeclMetadata) EmitDeclMetadata(); } /// ShouldInstrumentFunction - Return true if the current function should be /// instrumented with __cyg_profile_func_* calls bool CodeGenFunction::ShouldInstrumentFunction() { if (!CGM.getCodeGenOpts().InstrumentFunctions) return false; if (!CurFuncDecl || CurFuncDecl->hasAttr()) return false; return true; } /// EmitFunctionInstrumentation - Emit LLVM code to call the specified /// instrumentation function with the current function and the call site, if /// function instrumentation is enabled. void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) { // void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site); llvm::PointerType *PointerTy = Int8PtrTy; llvm::Type *ProfileFuncArgs[] = { PointerTy, PointerTy }; llvm::FunctionType *FunctionTy = llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), ProfileFuncArgs, false); llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn); llvm::CallInst *CallSite = Builder.CreateCall( CGM.getIntrinsic(llvm::Intrinsic::returnaddress), llvm::ConstantInt::get(Int32Ty, 0), "callsite"); Builder.CreateCall2(F, llvm::ConstantExpr::getBitCast(CurFn, PointerTy), CallSite); } void CodeGenFunction::EmitMCountInstrumentation() { llvm::FunctionType *FTy = llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), false); llvm::Constant *MCountFn = CGM.CreateRuntimeFunction(FTy, Target.getMCountName()); Builder.CreateCall(MCountFn); } void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy, llvm::Function *Fn, const CGFunctionInfo &FnInfo, const FunctionArgList &Args, SourceLocation StartLoc) { const Decl *D = GD.getDecl(); DidCallStackSave = false; CurCodeDecl = CurFuncDecl = D; FnRetTy = RetTy; CurFn = Fn; CurFnInfo = &FnInfo; assert(CurFn->isDeclaration() && "Function already has body?"); // Pass inline keyword to optimizer if it appears explicitly on any // declaration. if (const FunctionDecl *FD = dyn_cast_or_null(D)) for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(), RE = FD->redecls_end(); RI != RE; ++RI) if (RI->isInlineSpecified()) { Fn->addFnAttr(llvm::Attribute::InlineHint); break; } if (getContext().getLangOptions().OpenCL) { // Add metadata for a kernel function. if (const FunctionDecl *FD = dyn_cast_or_null(D)) if (FD->hasAttr()) { llvm::LLVMContext &Context = getLLVMContext(); llvm::NamedMDNode *OpenCLMetadata = CGM.getModule().getOrInsertNamedMetadata("opencl.kernels"); llvm::Value *Op = Fn; OpenCLMetadata->addOperand(llvm::MDNode::get(Context, Op)); } } llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn); // Create a marker to make it easy to insert allocas into the entryblock // later. Don't create this with the builder, because we don't want it // folded. llvm::Value *Undef = llvm::UndefValue::get(Int32Ty); AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB); if (Builder.isNamePreserving()) AllocaInsertPt->setName("allocapt"); ReturnBlock = getJumpDestInCurrentScope("return"); Builder.SetInsertPoint(EntryBB); // Emit subprogram debug descriptor. if (CGDebugInfo *DI = getDebugInfo()) { // FIXME: what is going on here and why does it ignore all these // interesting type properties? QualType FnType = getContext().getFunctionType(RetTy, 0, 0, FunctionProtoType::ExtProtoInfo()); DI->setLocation(StartLoc); DI->EmitFunctionStart(GD, FnType, CurFn, Builder); } if (ShouldInstrumentFunction()) EmitFunctionInstrumentation("__cyg_profile_func_enter"); if (CGM.getCodeGenOpts().InstrumentForProfiling) EmitMCountInstrumentation(); if (RetTy->isVoidType()) { // Void type; nothing to return. ReturnValue = 0; } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect && hasAggregateLLVMType(CurFnInfo->getReturnType())) { // Indirect aggregate return; emit returned value directly into sret slot. // This reduces code size, and affects correctness in C++. ReturnValue = CurFn->arg_begin(); } else { ReturnValue = CreateIRTemp(RetTy, "retval"); // Tell the epilog emitter to autorelease the result. We do this // now so that various specialized functions can suppress it // during their IR-generation. if (getLangOptions().ObjCAutoRefCount && !CurFnInfo->isReturnsRetained() && RetTy->isObjCRetainableType()) AutoreleaseResult = true; } EmitStartEHSpec(CurCodeDecl); PrologueCleanupDepth = EHStack.stable_begin(); EmitFunctionProlog(*CurFnInfo, CurFn, Args); if (D && isa(D) && cast(D)->isInstance()) CGM.getCXXABI().EmitInstanceFunctionProlog(*this); // If any of the arguments have a variably modified type, make sure to // emit the type size. for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); i != e; ++i) { QualType Ty = (*i)->getType(); if (Ty->isVariablyModifiedType()) EmitVariablyModifiedType(Ty); } } void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) { const FunctionDecl *FD = cast(CurGD.getDecl()); assert(FD->getBody()); EmitStmt(FD->getBody()); } /// Tries to mark the given function nounwind based on the /// non-existence of any throwing calls within it. We believe this is /// lightweight enough to do at -O0. static void TryMarkNoThrow(llvm::Function *F) { // LLVM treats 'nounwind' on a function as part of the type, so we // can't do this on functions that can be overwritten. if (F->mayBeOverridden()) return; for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI) for (llvm::BasicBlock::iterator BI = FI->begin(), BE = FI->end(); BI != BE; ++BI) if (llvm::CallInst *Call = dyn_cast(&*BI)) if (!Call->doesNotThrow()) return; F->setDoesNotThrow(true); } void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn, const CGFunctionInfo &FnInfo) { const FunctionDecl *FD = cast(GD.getDecl()); // Check if we should generate debug info for this function. if (CGM.getModuleDebugInfo() && !FD->hasAttr()) DebugInfo = CGM.getModuleDebugInfo(); FunctionArgList Args; QualType ResTy = FD->getResultType(); CurGD = GD; if (isa(FD) && cast(FD)->isInstance()) CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args); if (FD->getNumParams()) for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) Args.push_back(FD->getParamDecl(i)); SourceRange BodyRange; if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange(); // Emit the standard function prologue. StartFunction(GD, ResTy, Fn, FnInfo, Args, BodyRange.getBegin()); // Generate the body of the function. if (isa(FD)) EmitDestructorBody(Args); else if (isa(FD)) EmitConstructorBody(Args); else EmitFunctionBody(Args); // Emit the standard function epilogue. FinishFunction(BodyRange.getEnd()); // If we haven't marked the function nothrow through other means, do // a quick pass now to see if we can. if (!CurFn->doesNotThrow()) TryMarkNoThrow(CurFn); } /// ContainsLabel - Return true if the statement contains a label in it. If /// this statement is not executed normally, it not containing a label means /// that we can just remove the code. bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { // Null statement, not a label! if (S == 0) return false; // If this is a label, we have to emit the code, consider something like: // if (0) { ... foo: bar(); } goto foo; // // TODO: If anyone cared, we could track __label__'s, since we know that you // can't jump to one from outside their declared region. if (isa(S)) return true; // If this is a case/default statement, and we haven't seen a switch, we have // to emit the code. if (isa(S) && !IgnoreCaseStmts) return true; // If this is a switch statement, we want to ignore cases below it. if (isa(S)) IgnoreCaseStmts = true; // Scan subexpressions for verboten labels. for (Stmt::const_child_range I = S->children(); I; ++I) if (ContainsLabel(*I, IgnoreCaseStmts)) return true; return false; } /// containsBreak - Return true if the statement contains a break out of it. /// If the statement (recursively) contains a switch or loop with a break /// inside of it, this is fine. bool CodeGenFunction::containsBreak(const Stmt *S) { // Null statement, not a label! if (S == 0) return false; // If this is a switch or loop that defines its own break scope, then we can // include it and anything inside of it. if (isa(S) || isa(S) || isa(S) || isa(S)) return false; if (isa(S)) return true; // Scan subexpressions for verboten breaks. for (Stmt::const_child_range I = S->children(); I; ++I) if (containsBreak(*I)) return true; return false; } /// ConstantFoldsToSimpleInteger - If the specified expression does not fold /// to a constant, or if it does but contains a label, return false. If it /// constant folds return true and set the boolean result in Result. bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond, bool &ResultBool) { llvm::APInt ResultInt; if (!ConstantFoldsToSimpleInteger(Cond, ResultInt)) return false; ResultBool = ResultInt.getBoolValue(); return true; } /// ConstantFoldsToSimpleInteger - If the specified expression does not fold /// to a constant, or if it does but contains a label, return false. If it /// constant folds return true and set the folded value. bool CodeGenFunction:: ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APInt &ResultInt) { // FIXME: Rename and handle conversion of other evaluatable things // to bool. Expr::EvalResult Result; if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() || Result.HasSideEffects) return false; // Not foldable, not integer or not fully evaluatable. if (CodeGenFunction::ContainsLabel(Cond)) return false; // Contains a label. ResultInt = Result.Val.getInt(); return true; } /// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if /// statement) to the specified blocks. Based on the condition, this might try /// to simplify the codegen of the conditional based on the branch. /// void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, llvm::BasicBlock *TrueBlock, llvm::BasicBlock *FalseBlock) { Cond = Cond->IgnoreParens(); if (const BinaryOperator *CondBOp = dyn_cast(Cond)) { // Handle X && Y in a condition. if (CondBOp->getOpcode() == BO_LAnd) { // If we have "1 && X", simplify the code. "0 && X" would have constant // folded if the case was simple enough. bool ConstantBool = false; if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) && ConstantBool) { // br(1 && X) -> br(X). return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); } // If we have "X && 1", simplify the code to use an uncond branch. // "X && 0" would have been constant folded to 0. if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) && ConstantBool) { // br(X && 1) -> br(X). return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); } // Emit the LHS as a conditional. If the LHS conditional is false, we // want to jump to the FalseBlock. llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); ConditionalEvaluation eval(*this); EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); EmitBlock(LHSTrue); // Any temporaries created here are conditional. eval.begin(*this); EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); eval.end(*this); return; } if (CondBOp->getOpcode() == BO_LOr) { // If we have "0 || X", simplify the code. "1 || X" would have constant // folded if the case was simple enough. bool ConstantBool = false; if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) && !ConstantBool) { // br(0 || X) -> br(X). return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); } // If we have "X || 0", simplify the code to use an uncond branch. // "X || 1" would have been constant folded to 1. if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) && !ConstantBool) { // br(X || 0) -> br(X). return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); } // Emit the LHS as a conditional. If the LHS conditional is true, we // want to jump to the TrueBlock. llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); ConditionalEvaluation eval(*this); EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); EmitBlock(LHSFalse); // Any temporaries created here are conditional. eval.begin(*this); EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); eval.end(*this); return; } } if (const UnaryOperator *CondUOp = dyn_cast(Cond)) { // br(!x, t, f) -> br(x, f, t) if (CondUOp->getOpcode() == UO_LNot) return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); } if (const ConditionalOperator *CondOp = dyn_cast(Cond)) { // Handle ?: operator. // Just ignore GNU ?: extension. if (CondOp->getLHS()) { // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); ConditionalEvaluation cond(*this); EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); cond.begin(*this); EmitBlock(LHSBlock); EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); cond.end(*this); cond.begin(*this); EmitBlock(RHSBlock); EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); cond.end(*this); return; } } // Emit the code with the fully general case. llvm::Value *CondV = EvaluateExprAsBool(Cond); Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); } /// ErrorUnsupported - Print out an error that codegen doesn't support the /// specified stmt yet. void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, bool OmitOnError) { CGM.ErrorUnsupported(S, Type, OmitOnError); } /// emitNonZeroVLAInit - Emit the "zero" initialization of a /// variable-length array whose elements have a non-zero bit-pattern. /// /// \param src - a char* pointing to the bit-pattern for a single /// base element of the array /// \param sizeInChars - the total size of the VLA, in chars /// \param align - the total alignment of the VLA static void emitNonZeroVLAInit(CodeGenFunction &CGF, QualType baseType, llvm::Value *dest, llvm::Value *src, llvm::Value *sizeInChars) { std::pair baseSizeAndAlign = CGF.getContext().getTypeInfoInChars(baseType); CGBuilderTy &Builder = CGF.Builder; llvm::Value *baseSizeInChars = llvm::ConstantInt::get(CGF.IntPtrTy, baseSizeAndAlign.first.getQuantity()); llvm::Type *i8p = Builder.getInt8PtrTy(); llvm::Value *begin = Builder.CreateBitCast(dest, i8p, "vla.begin"); llvm::Value *end = Builder.CreateInBoundsGEP(dest, sizeInChars, "vla.end"); llvm::BasicBlock *originBB = CGF.Builder.GetInsertBlock(); llvm::BasicBlock *loopBB = CGF.createBasicBlock("vla-init.loop"); llvm::BasicBlock *contBB = CGF.createBasicBlock("vla-init.cont"); // Make a loop over the VLA. C99 guarantees that the VLA element // count must be nonzero. CGF.EmitBlock(loopBB); llvm::PHINode *cur = Builder.CreatePHI(i8p, 2, "vla.cur"); cur->addIncoming(begin, originBB); // memcpy the individual element bit-pattern. Builder.CreateMemCpy(cur, src, baseSizeInChars, baseSizeAndAlign.second.getQuantity(), /*volatile*/ false); // Go to the next element. llvm::Value *next = Builder.CreateConstInBoundsGEP1_32(cur, 1, "vla.next"); // Leave if that's the end of the VLA. llvm::Value *done = Builder.CreateICmpEQ(next, end, "vla-init.isdone"); Builder.CreateCondBr(done, contBB, loopBB); cur->addIncoming(next, loopBB); CGF.EmitBlock(contBB); } void CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) { // Ignore empty classes in C++. if (getContext().getLangOptions().CPlusPlus) { if (const RecordType *RT = Ty->getAs()) { if (cast(RT->getDecl())->isEmpty()) return; } } // Cast the dest ptr to the appropriate i8 pointer type. unsigned DestAS = cast(DestPtr->getType())->getAddressSpace(); llvm::Type *BP = Builder.getInt8PtrTy(DestAS); if (DestPtr->getType() != BP) DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); // Get size and alignment info for this aggregate. std::pair TypeInfo = getContext().getTypeInfoInChars(Ty); CharUnits Size = TypeInfo.first; CharUnits Align = TypeInfo.second; llvm::Value *SizeVal; const VariableArrayType *vla; // Don't bother emitting a zero-byte memset. if (Size.isZero()) { // But note that getTypeInfo returns 0 for a VLA. if (const VariableArrayType *vlaType = dyn_cast_or_null( getContext().getAsArrayType(Ty))) { QualType eltType; llvm::Value *numElts; llvm::tie(numElts, eltType) = getVLASize(vlaType); SizeVal = numElts; CharUnits eltSize = getContext().getTypeSizeInChars(eltType); if (!eltSize.isOne()) SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(eltSize)); vla = vlaType; } else { return; } } else { SizeVal = CGM.getSize(Size); vla = 0; } // If the type contains a pointer to data member we can't memset it to zero. // Instead, create a null constant and copy it to the destination. // TODO: there are other patterns besides zero that we can usefully memset, // like -1, which happens to be the pattern used by member-pointers. if (!CGM.getTypes().isZeroInitializable(Ty)) { // For a VLA, emit a single element, then splat that over the VLA. if (vla) Ty = getContext().getBaseElementType(vla); llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty); llvm::GlobalVariable *NullVariable = new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(), /*isConstant=*/true, llvm::GlobalVariable::PrivateLinkage, NullConstant, Twine()); llvm::Value *SrcPtr = Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy()); if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal); // Get and call the appropriate llvm.memcpy overload. Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align.getQuantity(), false); return; } // Otherwise, just memset the whole thing to zero. This is legal // because in LLVM, all default initializers (other than the ones we just // handled above) are guaranteed to have a bit pattern of all zeros. Builder.CreateMemSet(DestPtr, Builder.getInt8(0), SizeVal, Align.getQuantity(), false); } llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *L) { // Make sure that there is a block for the indirect goto. if (IndirectBranch == 0) GetIndirectGotoBlock(); llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock(); // Make sure the indirect branch includes all of the address-taken blocks. IndirectBranch->addDestination(BB); return llvm::BlockAddress::get(CurFn, BB); } llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() { // If we already made the indirect branch for indirect goto, return its block. if (IndirectBranch) return IndirectBranch->getParent(); CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto")); // Create the PHI node that indirect gotos will add entries to. llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, 0, "indirect.goto.dest"); // Create the indirect branch instruction. IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal); return IndirectBranch->getParent(); } /// Computes the length of an array in elements, as well as the base /// element type and a properly-typed first element pointer. llvm::Value *CodeGenFunction::emitArrayLength(const ArrayType *origArrayType, QualType &baseType, llvm::Value *&addr) { const ArrayType *arrayType = origArrayType; // If it's a VLA, we have to load the stored size. Note that // this is the size of the VLA in bytes, not its size in elements. llvm::Value *numVLAElements = 0; if (isa(arrayType)) { numVLAElements = getVLASize(cast(arrayType)).first; // Walk into all VLAs. This doesn't require changes to addr, // which has type T* where T is the first non-VLA element type. do { QualType elementType = arrayType->getElementType(); arrayType = getContext().getAsArrayType(elementType); // If we only have VLA components, 'addr' requires no adjustment. if (!arrayType) { baseType = elementType; return numVLAElements; } } while (isa(arrayType)); // We get out here only if we find a constant array type // inside the VLA. } // We have some number of constant-length arrays, so addr should // have LLVM type [M x [N x [...]]]*. Build a GEP that walks // down to the first element of addr. SmallVector gepIndices; // GEP down to the array type. llvm::ConstantInt *zero = Builder.getInt32(0); gepIndices.push_back(zero); // It's more efficient to calculate the count from the LLVM // constant-length arrays than to re-evaluate the array bounds. uint64_t countFromCLAs = 1; llvm::ArrayType *llvmArrayType = cast( cast(addr->getType())->getElementType()); while (true) { assert(isa(arrayType)); assert(cast(arrayType)->getSize().getZExtValue() == llvmArrayType->getNumElements()); gepIndices.push_back(zero); countFromCLAs *= llvmArrayType->getNumElements(); llvmArrayType = dyn_cast(llvmArrayType->getElementType()); if (!llvmArrayType) break; arrayType = getContext().getAsArrayType(arrayType->getElementType()); assert(arrayType && "LLVM and Clang types are out-of-synch"); } baseType = arrayType->getElementType(); // Create the actual GEP. addr = Builder.CreateInBoundsGEP(addr, gepIndices, "array.begin"); llvm::Value *numElements = llvm::ConstantInt::get(SizeTy, countFromCLAs); // If we had any VLA dimensions, factor them in. if (numVLAElements) numElements = Builder.CreateNUWMul(numVLAElements, numElements); return numElements; } std::pair CodeGenFunction::getVLASize(QualType type) { const VariableArrayType *vla = getContext().getAsVariableArrayType(type); assert(vla && "type was not a variable array type!"); return getVLASize(vla); } std::pair CodeGenFunction::getVLASize(const VariableArrayType *type) { // The number of elements so far; always size_t. llvm::Value *numElements = 0; QualType elementType; do { elementType = type->getElementType(); llvm::Value *vlaSize = VLASizeMap[type->getSizeExpr()]; assert(vlaSize && "no size for VLA!"); assert(vlaSize->getType() == SizeTy); if (!numElements) { numElements = vlaSize; } else { // It's undefined behavior if this wraps around, so mark it that way. numElements = Builder.CreateNUWMul(numElements, vlaSize); } } while ((type = getContext().getAsVariableArrayType(elementType))); return std::pair(numElements, elementType); } void CodeGenFunction::EmitVariablyModifiedType(QualType type) { assert(type->isVariablyModifiedType() && "Must pass variably modified type to EmitVLASizes!"); EnsureInsertPoint(); // We're going to walk down into the type and look for VLA // expressions. type = type.getCanonicalType(); do { assert(type->isVariablyModifiedType()); const Type *ty = type.getTypePtr(); switch (ty->getTypeClass()) { #define TYPE(Class, Base) #define ABSTRACT_TYPE(Class, Base) #define NON_CANONICAL_TYPE(Class, Base) case Type::Class: #define DEPENDENT_TYPE(Class, Base) case Type::Class: #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class: #include "clang/AST/TypeNodes.def" llvm_unreachable("unexpected dependent or non-canonical type!"); // These types are never variably-modified. case Type::Builtin: case Type::Complex: case Type::Vector: case Type::ExtVector: case Type::Record: case Type::Enum: case Type::ObjCObject: case Type::ObjCInterface: case Type::ObjCObjectPointer: llvm_unreachable("type class is never variably-modified!"); case Type::Pointer: type = cast(ty)->getPointeeType(); break; case Type::BlockPointer: type = cast(ty)->getPointeeType(); break; case Type::LValueReference: case Type::RValueReference: type = cast(ty)->getPointeeType(); break; case Type::MemberPointer: type = cast(ty)->getPointeeType(); break; case Type::ConstantArray: case Type::IncompleteArray: // Losing element qualification here is fine. type = cast(ty)->getElementType(); break; case Type::VariableArray: { // Losing element qualification here is fine. const VariableArrayType *vat = cast(ty); // Unknown size indication requires no size computation. // Otherwise, evaluate and record it. if (const Expr *size = vat->getSizeExpr()) { // It's possible that we might have emitted this already, // e.g. with a typedef and a pointer to it. llvm::Value *&entry = VLASizeMap[size]; if (!entry) { // Always zexting here would be wrong if it weren't // undefined behavior to have a negative bound. entry = Builder.CreateIntCast(EmitScalarExpr(size), SizeTy, /*signed*/ false); } } type = vat->getElementType(); break; } case Type::FunctionProto: case Type::FunctionNoProto: type = cast(ty)->getResultType(); break; } } while (type->isVariablyModifiedType()); } llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { if (getContext().getBuiltinVaListType()->isArrayType()) return EmitScalarExpr(E); return EmitLValue(E).getAddress(); } void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E, llvm::Constant *Init) { assert (Init && "Invalid DeclRefExpr initializer!"); if (CGDebugInfo *Dbg = getDebugInfo()) Dbg->EmitGlobalVariable(E->getDecl(), Init); } CodeGenFunction::PeepholeProtection CodeGenFunction::protectFromPeepholes(RValue rvalue) { // At the moment, the only aggressive peephole we do in IR gen // is trunc(zext) folding, but if we add more, we can easily // extend this protection. if (!rvalue.isScalar()) return PeepholeProtection(); llvm::Value *value = rvalue.getScalarVal(); if (!isa(value)) return PeepholeProtection(); // Just make an extra bitcast. assert(HaveInsertPoint()); llvm::Instruction *inst = new llvm::BitCastInst(value, value->getType(), "", Builder.GetInsertBlock()); PeepholeProtection protection; protection.Inst = inst; return protection; } void CodeGenFunction::unprotectFromPeepholes(PeepholeProtection protection) { if (!protection.Inst) return; // In theory, we could try to duplicate the peepholes now, but whatever. protection.Inst->eraseFromParent(); }