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Diffstat (limited to 'contrib/llvm/tools/clang/lib/CodeGen/CodeGenFunction.cpp')
| -rw-r--r-- | contrib/llvm/tools/clang/lib/CodeGen/CodeGenFunction.cpp | 1230 |
1 files changed, 1230 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/CodeGen/CodeGenFunction.cpp b/contrib/llvm/tools/clang/lib/CodeGen/CodeGenFunction.cpp new file mode 100644 index 0000000..eb6c436 --- /dev/null +++ b/contrib/llvm/tools/clang/lib/CodeGen/CodeGenFunction.cpp @@ -0,0 +1,1230 @@ +//===--- 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 "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) + : BlockFunction(cgm, *this, Builder), CGM(cgm), + Target(CGM.getContext().Target), + Builder(cgm.getModule().getContext()), + ExceptionSlot(0), DebugInfo(0), IndirectBranch(0), + SwitchInsn(0), CaseRangeBlock(0), InvokeDest(0), + DidCallStackSave(false), UnreachableBlock(0), + CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0), + ConditionalBranchLevel(0), TerminateLandingPad(0), TerminateHandler(0), + TrapBB(0) { + + // Get some frequently used types. + LLVMPointerWidth = Target.getPointerWidth(0); + llvm::LLVMContext &LLVMContext = CGM.getLLVMContext(); + IntPtrTy = llvm::IntegerType::get(LLVMContext, LLVMPointerWidth); + Int32Ty = llvm::Type::getInt32Ty(LLVMContext); + Int64Ty = llvm::Type::getInt64Ty(LLVMContext); + + Exceptions = getContext().getLangOptions().Exceptions; + CatchUndefined = getContext().getLangOptions().CatchUndefined; + CGM.getMangleContext().startNewFunction(); +} + +ASTContext &CodeGenFunction::getContext() const { + return CGM.getContext(); +} + + +llvm::Value *CodeGenFunction::GetAddrOfLocalVar(const VarDecl *VD) { + llvm::Value *Res = LocalDeclMap[VD]; + assert(Res && "Invalid argument to GetAddrOfLocalVar(), no decl!"); + return Res; +} + +llvm::Constant * +CodeGenFunction::GetAddrOfStaticLocalVar(const VarDecl *BVD) { + return cast<llvm::Constant>(GetAddrOfLocalVar(BVD)); +} + +const llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) { + return CGM.getTypes().ConvertTypeForMem(T); +} + +const llvm::Type *CodeGenFunction::ConvertType(QualType T) { + return CGM.getTypes().ConvertType(T); +} + +bool CodeGenFunction::hasAggregateLLVMType(QualType T) { + return T->isRecordType() || T->isArrayType() || T->isAnyComplexType() || + T->isMemberFunctionPointerType(); +} + +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.Block->use_empty()) { + ReturnBlock.Block->replaceAllUsesWith(CurBB); + delete ReturnBlock.Block; + } else + EmitBlock(ReturnBlock.Block); + 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.Block->hasOneUse()) { + llvm::BranchInst *BI = + dyn_cast<llvm::BranchInst>(*ReturnBlock.Block->use_begin()); + if (BI && BI->isUnconditional() && + BI->getSuccessor(0) == ReturnBlock.Block) { + // Reset insertion point and delete the branch. + Builder.SetInsertPoint(BI->getParent()); + BI->eraseFromParent(); + delete ReturnBlock.Block; + 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.Block); +} + +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!"); + + // Emit function epilog (to return). + EmitReturnBlock(); + + EmitFunctionInstrumentation("__cyg_profile_func_exit"); + + // Emit debug descriptor for function end. + if (CGDebugInfo *DI = getDebugInfo()) { + DI->setLocation(EndLoc); + DI->EmitRegionEnd(CurFn, 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<llvm::PHINode>(IndirectBranch->getAddress()); + if (PN->getNumIncomingValues() == 0) { + PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType())); + PN->eraseFromParent(); + } + } + + 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->hasAttr<NoInstrumentFunctionAttr>()) + 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) { + if (!ShouldInstrumentFunction()) + return; + + const llvm::PointerType *PointerTy; + const llvm::FunctionType *FunctionTy; + std::vector<const llvm::Type*> ProfileFuncArgs; + + // void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site); + PointerTy = llvm::Type::getInt8PtrTy(VMContext); + ProfileFuncArgs.push_back(PointerTy); + ProfileFuncArgs.push_back(PointerTy); + FunctionTy = llvm::FunctionType::get( + llvm::Type::getVoidTy(VMContext), + ProfileFuncArgs, false); + + llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn); + llvm::CallInst *CallSite = Builder.CreateCall( + CGM.getIntrinsic(llvm::Intrinsic::returnaddress, 0, 0), + llvm::ConstantInt::get(Int32Ty, 0), + "callsite"); + + Builder.CreateCall2(F, + llvm::ConstantExpr::getBitCast(CurFn, PointerTy), + CallSite); +} + +void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy, + llvm::Function *Fn, + const FunctionArgList &Args, + SourceLocation StartLoc) { + const Decl *D = GD.getDecl(); + + DidCallStackSave = false; + CurCodeDecl = CurFuncDecl = D; + FnRetTy = RetTy; + CurFn = Fn; + 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<FunctionDecl>(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; + } + + 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); + + QualType FnType = getContext().getFunctionType(RetTy, 0, 0, false, 0, + false, false, 0, 0, + /*FIXME?*/ + FunctionType::ExtInfo()); + + // Emit subprogram debug descriptor. + if (CGDebugInfo *DI = getDebugInfo()) { + DI->setLocation(StartLoc); + DI->EmitFunctionStart(GD, FnType, CurFn, Builder); + } + + EmitFunctionInstrumentation("__cyg_profile_func_enter"); + + // FIXME: Leaked. + // CC info is ignored, hopefully? + CurFnInfo = &CGM.getTypes().getFunctionInfo(FnRetTy, Args, + FunctionType::ExtInfo()); + + 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"); + } + + EmitStartEHSpec(CurCodeDecl); + EmitFunctionProlog(*CurFnInfo, CurFn, Args); + + if (CXXThisDecl) + CXXThisValue = Builder.CreateLoad(LocalDeclMap[CXXThisDecl], "this"); + if (CXXVTTDecl) + CXXVTTValue = Builder.CreateLoad(LocalDeclMap[CXXVTTDecl], "vtt"); + + // 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->second; + + if (Ty->isVariablyModifiedType()) + EmitVLASize(Ty); + } +} + +void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) { + const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl()); + assert(FD->getBody()); + EmitStmt(FD->getBody()); +} + +void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn) { + const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl()); + + // Check if we should generate debug info for this function. + if (CGM.getDebugInfo() && !FD->hasAttr<NoDebugAttr>()) + DebugInfo = CGM.getDebugInfo(); + + FunctionArgList Args; + + CurGD = GD; + if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) { + if (MD->isInstance()) { + // Create the implicit 'this' decl. + // FIXME: I'm not entirely sure I like using a fake decl just for code + // generation. Maybe we can come up with a better way? + CXXThisDecl = ImplicitParamDecl::Create(getContext(), 0, + FD->getLocation(), + &getContext().Idents.get("this"), + MD->getThisType(getContext())); + Args.push_back(std::make_pair(CXXThisDecl, CXXThisDecl->getType())); + + // Check if we need a VTT parameter as well. + if (CodeGenVTables::needsVTTParameter(GD)) { + // FIXME: The comment about using a fake decl above applies here too. + QualType T = getContext().getPointerType(getContext().VoidPtrTy); + CXXVTTDecl = + ImplicitParamDecl::Create(getContext(), 0, FD->getLocation(), + &getContext().Idents.get("vtt"), T); + Args.push_back(std::make_pair(CXXVTTDecl, CXXVTTDecl->getType())); + } + } + } + + if (FD->getNumParams()) { + const FunctionProtoType* FProto = FD->getType()->getAs<FunctionProtoType>(); + assert(FProto && "Function def must have prototype!"); + + for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) + Args.push_back(std::make_pair(FD->getParamDecl(i), + FProto->getArgType(i))); + } + + SourceRange BodyRange; + if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange(); + + // Emit the standard function prologue. + StartFunction(GD, FD->getResultType(), Fn, Args, BodyRange.getBegin()); + + // Generate the body of the function. + if (isa<CXXDestructorDecl>(FD)) + EmitDestructorBody(Args); + else if (isa<CXXConstructorDecl>(FD)) + EmitConstructorBody(Args); + else + EmitFunctionBody(Args); + + // Emit the standard function epilogue. + FinishFunction(BodyRange.getEnd()); + + // Destroy the 'this' declaration. + if (CXXThisDecl) + CXXThisDecl->Destroy(getContext()); + + // Destroy the VTT declaration. + if (CXXVTTDecl) + CXXVTTDecl->Destroy(getContext()); +} + +/// 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; + if (isa<LabelStmt>(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<SwitchCase>(S) && !IgnoreCaseStmts) + return true; + + // If this is a switch statement, we want to ignore cases below it. + if (isa<SwitchStmt>(S)) + IgnoreCaseStmts = true; + + // Scan subexpressions for verboten labels. + for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end(); + I != E; ++I) + if (ContainsLabel(*I, IgnoreCaseStmts)) + return true; + + return false; +} + + +/// ConstantFoldsToSimpleInteger - If the sepcified expression does not fold to +/// a constant, or if it does but contains a label, return 0. If it constant +/// folds to 'true' and does not contain a label, return 1, if it constant folds +/// to 'false' and does not contain a label, return -1. +int CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond) { + // 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 0; // Not foldable, not integer or not fully evaluatable. + + if (CodeGenFunction::ContainsLabel(Cond)) + return 0; // Contains a label. + + return Result.Val.getInt().getBoolValue() ? 1 : -1; +} + + +/// 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) { + if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) + return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock); + + if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { + // Handle X && Y in a condition. + if (CondBOp->getOpcode() == BinaryOperator::LAnd) { + // If we have "1 && X", simplify the code. "0 && X" would have constant + // folded if the case was simple enough. + if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == 1) { + // 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()) == 1) { + // 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"); + EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); + EmitBlock(LHSTrue); + + // Any temporaries created here are conditional. + BeginConditionalBranch(); + EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); + EndConditionalBranch(); + + return; + } else if (CondBOp->getOpcode() == BinaryOperator::LOr) { + // If we have "0 || X", simplify the code. "1 || X" would have constant + // folded if the case was simple enough. + if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == -1) { + // 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()) == -1) { + // 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"); + EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); + EmitBlock(LHSFalse); + + // Any temporaries created here are conditional. + BeginConditionalBranch(); + EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); + EndConditionalBranch(); + + return; + } + } + + if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { + // br(!x, t, f) -> br(x, f, t) + if (CondUOp->getOpcode() == UnaryOperator::LNot) + return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); + } + + if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(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"); + EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); + EmitBlock(LHSBlock); + EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); + EmitBlock(RHSBlock); + EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); + 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); +} + +void +CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) { + // 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. + if (CGM.getTypes().ContainsPointerToDataMember(Ty)) { + llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty); + + llvm::GlobalVariable *NullVariable = + new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(), + /*isConstant=*/true, + llvm::GlobalVariable::PrivateLinkage, + NullConstant, llvm::Twine()); + EmitAggregateCopy(DestPtr, NullVariable, Ty, /*isVolatile=*/false); + return; + } + + + // Ignore empty classes in C++. + if (getContext().getLangOptions().CPlusPlus) { + if (const RecordType *RT = Ty->getAs<RecordType>()) { + if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty()) + 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. + const llvm::Type *BP = llvm::Type::getInt8PtrTy(VMContext); + if (DestPtr->getType() != BP) + DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); + + // Get size and alignment info for this aggregate. + std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); + + // Don't bother emitting a zero-byte memset. + if (TypeInfo.first == 0) + return; + + // FIXME: Handle variable sized types. + Builder.CreateCall5(CGM.getMemSetFn(BP, IntPtrTy), DestPtr, + llvm::Constant::getNullValue(llvm::Type::getInt8Ty(VMContext)), + // TypeInfo.first describes size in bits. + llvm::ConstantInt::get(IntPtrTy, TypeInfo.first/8), + llvm::ConstantInt::get(Int32Ty, TypeInfo.second/8), + llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext), + 0)); +} + +llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelStmt *L) { + // Make sure that there is a block for the indirect goto. + if (IndirectBranch == 0) + GetIndirectGotoBlock(); + + llvm::BasicBlock *BB = getJumpDestForLabel(L).Block; + + // 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")); + + const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext); + + // Create the PHI node that indirect gotos will add entries to. + llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, "indirect.goto.dest"); + + // Create the indirect branch instruction. + IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal); + return IndirectBranch->getParent(); +} + +llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) { + llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; + + assert(SizeEntry && "Did not emit size for type"); + return SizeEntry; +} + +llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) { + assert(Ty->isVariablyModifiedType() && + "Must pass variably modified type to EmitVLASizes!"); + + EnsureInsertPoint(); + + if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) { + llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; + + if (!SizeEntry) { + const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); + + // Get the element size; + QualType ElemTy = VAT->getElementType(); + llvm::Value *ElemSize; + if (ElemTy->isVariableArrayType()) + ElemSize = EmitVLASize(ElemTy); + else + ElemSize = llvm::ConstantInt::get(SizeTy, + getContext().getTypeSizeInChars(ElemTy).getQuantity()); + + llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr()); + NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp"); + + SizeEntry = Builder.CreateMul(ElemSize, NumElements); + } + + return SizeEntry; + } + + if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) { + EmitVLASize(AT->getElementType()); + return 0; + } + + const PointerType *PT = Ty->getAs<PointerType>(); + assert(PT && "unknown VM type!"); + EmitVLASize(PT->getPointeeType()); + return 0; +} + +llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { + if (CGM.getContext().getBuiltinVaListType()->isArrayType()) + return EmitScalarExpr(E); + return EmitLValue(E).getAddress(); +} + +/// Pops cleanup blocks until the given savepoint is reached. +void CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old) { + assert(Old.isValid()); + + EHScopeStack::iterator E = EHStack.find(Old); + while (EHStack.begin() != E) + PopCleanupBlock(); +} + +/// Destroys a cleanup if it was unused. +static void DestroyCleanup(CodeGenFunction &CGF, + llvm::BasicBlock *Entry, + llvm::BasicBlock *Exit) { + assert(Entry->use_empty() && "destroying cleanup with uses!"); + assert(Exit->getTerminator() == 0 && + "exit has terminator but entry has no predecessors!"); + + // This doesn't always remove the entire cleanup, but it's much + // safer as long as we don't know what blocks belong to the cleanup. + // A *much* better approach if we care about this inefficiency would + // be to lazily emit the cleanup. + + // If the exit block is distinct from the entry, give it a branch to + // an unreachable destination. This preserves the well-formedness + // of the IR. + if (Entry != Exit) + llvm::BranchInst::Create(CGF.getUnreachableBlock(), Exit); + + assert(!Entry->getParent() && "cleanup entry already positioned?"); + // We can't just delete the entry; we have to kill any references to + // its instructions in other blocks. + for (llvm::BasicBlock::iterator I = Entry->begin(), E = Entry->end(); + I != E; ++I) + if (!I->use_empty()) + I->replaceAllUsesWith(llvm::UndefValue::get(I->getType())); + delete Entry; +} + +/// Creates a switch instruction to thread branches out of the given +/// block (which is the exit block of a cleanup). +static void CreateCleanupSwitch(CodeGenFunction &CGF, + llvm::BasicBlock *Block) { + if (Block->getTerminator()) { + assert(isa<llvm::SwitchInst>(Block->getTerminator()) && + "cleanup block already has a terminator, but it isn't a switch"); + return; + } + + llvm::Value *DestCodePtr + = CGF.CreateTempAlloca(CGF.Builder.getInt32Ty(), "cleanup.dst"); + CGBuilderTy Builder(Block); + llvm::Value *DestCode = Builder.CreateLoad(DestCodePtr, "tmp"); + + // Create a switch instruction to determine where to jump next. + Builder.CreateSwitch(DestCode, CGF.getUnreachableBlock()); +} + +/// Attempts to reduce a cleanup's entry block to a fallthrough. This +/// is basically llvm::MergeBlockIntoPredecessor, except +/// simplified/optimized for the tighter constraints on cleanup +/// blocks. +static void SimplifyCleanupEntry(CodeGenFunction &CGF, + llvm::BasicBlock *Entry) { + llvm::BasicBlock *Pred = Entry->getSinglePredecessor(); + if (!Pred) return; + + llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Pred->getTerminator()); + if (!Br || Br->isConditional()) return; + assert(Br->getSuccessor(0) == Entry); + + // If we were previously inserting at the end of the cleanup entry + // block, we'll need to continue inserting at the end of the + // predecessor. + bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry; + assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end()); + + // Kill the branch. + Br->eraseFromParent(); + + // Merge the blocks. + Pred->getInstList().splice(Pred->end(), Entry->getInstList()); + + // Kill the entry block. + Entry->eraseFromParent(); + + if (WasInsertBlock) + CGF.Builder.SetInsertPoint(Pred); +} + +/// Attempts to reduce an cleanup's exit switch to an unconditional +/// branch. +static void SimplifyCleanupExit(llvm::BasicBlock *Exit) { + llvm::TerminatorInst *Terminator = Exit->getTerminator(); + assert(Terminator && "completed cleanup exit has no terminator"); + + llvm::SwitchInst *Switch = dyn_cast<llvm::SwitchInst>(Terminator); + if (!Switch) return; + if (Switch->getNumCases() != 2) return; // default + 1 + + llvm::LoadInst *Cond = cast<llvm::LoadInst>(Switch->getCondition()); + llvm::AllocaInst *CondVar = cast<llvm::AllocaInst>(Cond->getPointerOperand()); + + // Replace the switch instruction with an unconditional branch. + llvm::BasicBlock *Dest = Switch->getSuccessor(1); // default is 0 + Switch->eraseFromParent(); + llvm::BranchInst::Create(Dest, Exit); + + // Delete all uses of the condition variable. + Cond->eraseFromParent(); + while (!CondVar->use_empty()) + cast<llvm::StoreInst>(*CondVar->use_begin())->eraseFromParent(); + + // Delete the condition variable itself. + CondVar->eraseFromParent(); +} + +/// Threads a branch fixup through a cleanup block. +static void ThreadFixupThroughCleanup(CodeGenFunction &CGF, + BranchFixup &Fixup, + llvm::BasicBlock *Entry, + llvm::BasicBlock *Exit) { + if (!Exit->getTerminator()) + CreateCleanupSwitch(CGF, Exit); + + // Find the switch and its destination index alloca. + llvm::SwitchInst *Switch = cast<llvm::SwitchInst>(Exit->getTerminator()); + llvm::Value *DestCodePtr = + cast<llvm::LoadInst>(Switch->getCondition())->getPointerOperand(); + + // Compute the index of the new case we're adding to the switch. + unsigned Index = Switch->getNumCases(); + + const llvm::IntegerType *i32 = llvm::Type::getInt32Ty(CGF.getLLVMContext()); + llvm::ConstantInt *IndexV = llvm::ConstantInt::get(i32, Index); + + // Set the index in the origin block. + new llvm::StoreInst(IndexV, DestCodePtr, Fixup.Origin); + + // Add a case to the switch. + Switch->addCase(IndexV, Fixup.Destination); + + // Change the last branch to point to the cleanup entry block. + Fixup.LatestBranch->setSuccessor(Fixup.LatestBranchIndex, Entry); + + // And finally, update the fixup. + Fixup.LatestBranch = Switch; + Fixup.LatestBranchIndex = Index; +} + +/// Try to simplify both the entry and exit edges of a cleanup. +static void SimplifyCleanupEdges(CodeGenFunction &CGF, + llvm::BasicBlock *Entry, + llvm::BasicBlock *Exit) { + + // Given their current implementations, it's important to run these + // in this order: SimplifyCleanupEntry will delete Entry if it can + // be merged into its predecessor, which will then break + // SimplifyCleanupExit if (as is common) Entry == Exit. + + SimplifyCleanupExit(Exit); + SimplifyCleanupEntry(CGF, Entry); +} + +static void EmitLazyCleanup(CodeGenFunction &CGF, + EHScopeStack::LazyCleanup *Fn, + bool ForEH) { + if (ForEH) CGF.EHStack.pushTerminate(); + Fn->Emit(CGF, ForEH); + if (ForEH) CGF.EHStack.popTerminate(); + assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?"); +} + +static void SplitAndEmitLazyCleanup(CodeGenFunction &CGF, + EHScopeStack::LazyCleanup *Fn, + bool ForEH, + llvm::BasicBlock *Entry) { + assert(Entry && "no entry block for cleanup"); + + // Remove the switch and load from the end of the entry block. + llvm::Instruction *Switch = &Entry->getInstList().back(); + Entry->getInstList().remove(Switch); + assert(isa<llvm::SwitchInst>(Switch)); + llvm::Instruction *Load = &Entry->getInstList().back(); + Entry->getInstList().remove(Load); + assert(isa<llvm::LoadInst>(Load)); + + assert(Entry->getInstList().empty() && + "lazy cleanup block not empty after removing load/switch pair?"); + + // Emit the actual cleanup at the end of the entry block. + CGF.Builder.SetInsertPoint(Entry); + EmitLazyCleanup(CGF, Fn, ForEH); + + // Put the load and switch at the end of the exit block. + llvm::BasicBlock *Exit = CGF.Builder.GetInsertBlock(); + Exit->getInstList().push_back(Load); + Exit->getInstList().push_back(Switch); + + // Clean up the edges if possible. + SimplifyCleanupEdges(CGF, Entry, Exit); + + CGF.Builder.ClearInsertionPoint(); +} + +static void PopLazyCleanupBlock(CodeGenFunction &CGF) { + assert(isa<EHLazyCleanupScope>(*CGF.EHStack.begin()) && "top not a cleanup!"); + EHLazyCleanupScope &Scope = cast<EHLazyCleanupScope>(*CGF.EHStack.begin()); + assert(Scope.getFixupDepth() <= CGF.EHStack.getNumBranchFixups()); + + // Check whether we need an EH cleanup. This is only true if we've + // generated a lazy EH cleanup block. + llvm::BasicBlock *EHEntry = Scope.getEHBlock(); + bool RequiresEHCleanup = (EHEntry != 0); + + // Check the three conditions which might require a normal cleanup: + + // - whether there are branch fix-ups through this cleanup + unsigned FixupDepth = Scope.getFixupDepth(); + bool HasFixups = CGF.EHStack.getNumBranchFixups() != FixupDepth; + + // - whether control has already been threaded through this cleanup + llvm::BasicBlock *NormalEntry = Scope.getNormalBlock(); + bool HasExistingBranches = (NormalEntry != 0); + + // - whether there's a fallthrough + llvm::BasicBlock *FallthroughSource = CGF.Builder.GetInsertBlock(); + bool HasFallthrough = (FallthroughSource != 0); + + bool RequiresNormalCleanup = false; + if (Scope.isNormalCleanup() && + (HasFixups || HasExistingBranches || HasFallthrough)) { + RequiresNormalCleanup = true; + } + + // If we don't need the cleanup at all, we're done. + if (!RequiresNormalCleanup && !RequiresEHCleanup) { + CGF.EHStack.popCleanup(); + assert(CGF.EHStack.getNumBranchFixups() == 0 || + CGF.EHStack.hasNormalCleanups()); + return; + } + + // Copy the cleanup emission data out. Note that SmallVector + // guarantees maximal alignment for its buffer regardless of its + // type parameter. + llvm::SmallVector<char, 8*sizeof(void*)> CleanupBuffer; + CleanupBuffer.reserve(Scope.getCleanupSize()); + memcpy(CleanupBuffer.data(), + Scope.getCleanupBuffer(), Scope.getCleanupSize()); + CleanupBuffer.set_size(Scope.getCleanupSize()); + EHScopeStack::LazyCleanup *Fn = + reinterpret_cast<EHScopeStack::LazyCleanup*>(CleanupBuffer.data()); + + // We're done with the scope; pop it off so we can emit the cleanups. + CGF.EHStack.popCleanup(); + + if (RequiresNormalCleanup) { + // If we have a fallthrough and no other need for the cleanup, + // emit it directly. + if (HasFallthrough && !HasFixups && !HasExistingBranches) { + EmitLazyCleanup(CGF, Fn, /*ForEH*/ false); + + // Otherwise, the best approach is to thread everything through + // the cleanup block and then try to clean up after ourselves. + } else { + // Force the entry block to exist. + if (!HasExistingBranches) { + NormalEntry = CGF.createBasicBlock("cleanup"); + CreateCleanupSwitch(CGF, NormalEntry); + } + + CGF.EmitBlock(NormalEntry); + + // Thread the fallthrough edge through the (momentarily trivial) + // cleanup. + llvm::BasicBlock *FallthroughDestination = 0; + if (HasFallthrough) { + assert(isa<llvm::BranchInst>(FallthroughSource->getTerminator())); + FallthroughDestination = CGF.createBasicBlock("cleanup.cont"); + + BranchFixup Fix; + Fix.Destination = FallthroughDestination; + Fix.LatestBranch = FallthroughSource->getTerminator(); + Fix.LatestBranchIndex = 0; + Fix.Origin = Fix.LatestBranch; + + // Restore fixup invariant. EmitBlock added a branch to the + // cleanup which we need to redirect to the destination. + cast<llvm::BranchInst>(Fix.LatestBranch) + ->setSuccessor(0, Fix.Destination); + + ThreadFixupThroughCleanup(CGF, Fix, NormalEntry, NormalEntry); + } + + // Thread any "real" fixups we need to thread. + for (unsigned I = FixupDepth, E = CGF.EHStack.getNumBranchFixups(); + I != E; ++I) + if (CGF.EHStack.getBranchFixup(I).Destination) + ThreadFixupThroughCleanup(CGF, CGF.EHStack.getBranchFixup(I), + NormalEntry, NormalEntry); + + SplitAndEmitLazyCleanup(CGF, Fn, /*ForEH*/ false, NormalEntry); + + if (HasFallthrough) + CGF.EmitBlock(FallthroughDestination); + } + } + + // Emit the EH cleanup if required. + if (RequiresEHCleanup) { + CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP(); + CGF.EmitBlock(EHEntry); + SplitAndEmitLazyCleanup(CGF, Fn, /*ForEH*/ true, EHEntry); + CGF.Builder.restoreIP(SavedIP); + } +} + +/// Pops a cleanup block. If the block includes a normal cleanup, the +/// current insertion point is threaded through the cleanup, as are +/// any branch fixups on the cleanup. +void CodeGenFunction::PopCleanupBlock() { + assert(!EHStack.empty() && "cleanup stack is empty!"); + if (isa<EHLazyCleanupScope>(*EHStack.begin())) + return PopLazyCleanupBlock(*this); + + assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!"); + EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin()); + assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups()); + + // Handle the EH cleanup if (1) there is one and (2) it's different + // from the normal cleanup. + if (Scope.isEHCleanup() && + Scope.getEHEntry() != Scope.getNormalEntry()) { + llvm::BasicBlock *EHEntry = Scope.getEHEntry(); + llvm::BasicBlock *EHExit = Scope.getEHExit(); + + if (EHEntry->use_empty()) { + DestroyCleanup(*this, EHEntry, EHExit); + } else { + // TODO: this isn't really the ideal location to put this EH + // cleanup, but lazy emission is a better solution than trying + // to pick a better spot. + CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP(); + EmitBlock(EHEntry); + Builder.restoreIP(SavedIP); + + SimplifyCleanupEdges(*this, EHEntry, EHExit); + } + } + + // If we only have an EH cleanup, we don't really need to do much + // here. Branch fixups just naturally drop down to the enclosing + // cleanup scope. + if (!Scope.isNormalCleanup()) { + EHStack.popCleanup(); + assert(EHStack.getNumBranchFixups() == 0 || EHStack.hasNormalCleanups()); + return; + } + + // Check whether the scope has any fixups that need to be threaded. + unsigned FixupDepth = Scope.getFixupDepth(); + bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth; + + // Grab the entry and exit blocks. + llvm::BasicBlock *Entry = Scope.getNormalEntry(); + llvm::BasicBlock *Exit = Scope.getNormalExit(); + + // Check whether anything's been threaded through the cleanup already. + assert((Exit->getTerminator() == 0) == Entry->use_empty() && + "cleanup entry/exit mismatch"); + bool HasExistingBranches = !Entry->use_empty(); + + // Check whether we need to emit a "fallthrough" branch through the + // cleanup for the current insertion point. + llvm::BasicBlock *FallThrough = Builder.GetInsertBlock(); + if (FallThrough && FallThrough->getTerminator()) + FallThrough = 0; + + // If *nothing* is using the cleanup, kill it. + if (!FallThrough && !HasFixups && !HasExistingBranches) { + EHStack.popCleanup(); + DestroyCleanup(*this, Entry, Exit); + return; + } + + // Otherwise, add the block to the function. + EmitBlock(Entry); + + if (FallThrough) + Builder.SetInsertPoint(Exit); + else + Builder.ClearInsertionPoint(); + + // Fast case: if we don't have to add any fixups, and either + // we don't have a fallthrough or the cleanup wasn't previously + // used, then the setup above is sufficient. + if (!HasFixups) { + if (!FallThrough) { + assert(HasExistingBranches && "no reason for cleanup but didn't kill before"); + EHStack.popCleanup(); + SimplifyCleanupEdges(*this, Entry, Exit); + return; + } else if (!HasExistingBranches) { + assert(FallThrough && "no reason for cleanup but didn't kill before"); + // We can't simplify the exit edge in this case because we're + // already inserting at the end of the exit block. + EHStack.popCleanup(); + SimplifyCleanupEntry(*this, Entry); + return; + } + } + + // Otherwise we're going to have to thread things through the cleanup. + llvm::SmallVector<BranchFixup*, 8> Fixups; + + // Synthesize a fixup for the current insertion point. + BranchFixup Cur; + if (FallThrough) { + Cur.Destination = createBasicBlock("cleanup.cont"); + Cur.LatestBranch = FallThrough->getTerminator(); + Cur.LatestBranchIndex = 0; + Cur.Origin = Cur.LatestBranch; + + // Restore fixup invariant. EmitBlock added a branch to the cleanup + // which we need to redirect to the destination. + cast<llvm::BranchInst>(Cur.LatestBranch)->setSuccessor(0, Cur.Destination); + + Fixups.push_back(&Cur); + } else { + Cur.Destination = 0; + } + + // Collect any "real" fixups we need to thread. + for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups(); + I != E; ++I) + if (EHStack.getBranchFixup(I).Destination) + Fixups.push_back(&EHStack.getBranchFixup(I)); + + assert(!Fixups.empty() && "no fixups, invariants broken!"); + + // If there's only a single fixup to thread through, do so with + // unconditional branches. This only happens if there's a single + // branch and no fallthrough. + if (Fixups.size() == 1 && !HasExistingBranches) { + Fixups[0]->LatestBranch->setSuccessor(Fixups[0]->LatestBranchIndex, Entry); + llvm::BranchInst *Br = + llvm::BranchInst::Create(Fixups[0]->Destination, Exit); + Fixups[0]->LatestBranch = Br; + Fixups[0]->LatestBranchIndex = 0; + + // Otherwise, force a switch statement and thread everything through + // the switch. + } else { + CreateCleanupSwitch(*this, Exit); + for (unsigned I = 0, E = Fixups.size(); I != E; ++I) + ThreadFixupThroughCleanup(*this, *Fixups[I], Entry, Exit); + } + + // Emit the fallthrough destination block if necessary. + if (Cur.Destination) + EmitBlock(Cur.Destination); + + // We're finally done with the cleanup. + EHStack.popCleanup(); +} + +void CodeGenFunction::EmitBranchThroughCleanup(JumpDest Dest) { + if (!HaveInsertPoint()) + return; + + // Create the branch. + llvm::BranchInst *BI = Builder.CreateBr(Dest.Block); + + // If we're not in a cleanup scope, we don't need to worry about + // fixups. + if (!EHStack.hasNormalCleanups()) { + Builder.ClearInsertionPoint(); + return; + } + + // Initialize a fixup. + BranchFixup Fixup; + Fixup.Destination = Dest.Block; + Fixup.Origin = BI; + Fixup.LatestBranch = BI; + Fixup.LatestBranchIndex = 0; + + // If we can't resolve the destination cleanup scope, just add this + // to the current cleanup scope. + if (!Dest.ScopeDepth.isValid()) { + EHStack.addBranchFixup() = Fixup; + Builder.ClearInsertionPoint(); + return; + } + + for (EHScopeStack::iterator I = EHStack.begin(), + E = EHStack.find(Dest.ScopeDepth); I != E; ++I) { + if (isa<EHCleanupScope>(*I)) { + EHCleanupScope &Scope = cast<EHCleanupScope>(*I); + if (Scope.isNormalCleanup()) + ThreadFixupThroughCleanup(*this, Fixup, Scope.getNormalEntry(), + Scope.getNormalExit()); + } else if (isa<EHLazyCleanupScope>(*I)) { + EHLazyCleanupScope &Scope = cast<EHLazyCleanupScope>(*I); + if (Scope.isNormalCleanup()) { + llvm::BasicBlock *Block = Scope.getNormalBlock(); + if (!Block) { + Block = createBasicBlock("cleanup"); + Scope.setNormalBlock(Block); + } + ThreadFixupThroughCleanup(*this, Fixup, Block, Block); + } + } + } + + Builder.ClearInsertionPoint(); +} + +void CodeGenFunction::EmitBranchThroughEHCleanup(JumpDest Dest) { + if (!HaveInsertPoint()) + return; + + // Create the branch. + llvm::BranchInst *BI = Builder.CreateBr(Dest.Block); + + // If we're not in a cleanup scope, we don't need to worry about + // fixups. + if (!EHStack.hasEHCleanups()) { + Builder.ClearInsertionPoint(); + return; + } + + // Initialize a fixup. + BranchFixup Fixup; + Fixup.Destination = Dest.Block; + Fixup.Origin = BI; + Fixup.LatestBranch = BI; + Fixup.LatestBranchIndex = 0; + + // We should never get invalid scope depths for these: invalid scope + // depths only arise for as-yet-unemitted labels, and we can't do an + // EH-unwind to one of those. + assert(Dest.ScopeDepth.isValid() && "invalid scope depth on EH dest?"); + + for (EHScopeStack::iterator I = EHStack.begin(), + E = EHStack.find(Dest.ScopeDepth); I != E; ++I) { + if (isa<EHCleanupScope>(*I)) { + EHCleanupScope &Scope = cast<EHCleanupScope>(*I); + if (Scope.isEHCleanup()) + ThreadFixupThroughCleanup(*this, Fixup, Scope.getEHEntry(), + Scope.getEHExit()); + } else if (isa<EHLazyCleanupScope>(*I)) { + EHLazyCleanupScope &Scope = cast<EHLazyCleanupScope>(*I); + if (Scope.isEHCleanup()) { + llvm::BasicBlock *Block = Scope.getEHBlock(); + if (!Block) { + Block = createBasicBlock("eh.cleanup"); + Scope.setEHBlock(Block); + } + ThreadFixupThroughCleanup(*this, Fixup, Block, Block); + } + } + } + + Builder.ClearInsertionPoint(); +} |
