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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 | 790 |
1 files changed, 790 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..f1b7286 --- /dev/null +++ b/contrib/llvm/tools/clang/lib/CodeGen/CodeGenFunction.cpp @@ -0,0 +1,790 @@ +//===--- 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().Target), Builder(cgm.getModule().getContext()), + BlockInfo(0), BlockPointer(0), + NormalCleanupDest(0), EHCleanupDest(0), NextCleanupDestIndex(1), + ExceptionSlot(0), DebugInfo(0), IndirectBranch(0), + SwitchInsn(0), CaseRangeBlock(0), + DidCallStackSave(false), 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(); +} + +ASTContext &CodeGenFunction::getContext() const { + return CGM.getContext(); +} + + +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->isObjCObjectType(); +} + +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<llvm::BranchInst>(*ReturnBlock.getBlock()->use_begin()); + if (BI && BI->isUnconditional() && + BI->getSuccessor(0) == ReturnBlock.getBlock()) { + // Reset insertion point and delete the branch. + 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!"); + + // 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<llvm::PHINode>(IndirectBranch->getAddress()); + if (PN->getNumIncomingValues() == 0) { + PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType())); + PN->eraseFromParent(); + } + } + + EmitIfUsed(*this, RethrowBlock.getBlock()); + 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) { + 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 = Int8PtrTy; + ProfileFuncArgs.push_back(PointerTy); + ProfileFuncArgs.push_back(PointerTy); + 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, 0, 0), + 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 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; + } + + if (getContext().getLangOptions().OpenCL) { + // Add metadata for a kernel function. + if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) + if (FD->hasAttr<OpenCLKernelAttr>()) { + llvm::LLVMContext &Context = getLLVMContext(); + llvm::NamedMDNode *OpenCLMetadata = + CGM.getModule().getOrInsertNamedMetadata("opencl.kernels"); + + llvm::Value *Op = Fn; + OpenCLMetadata->addOperand(llvm::MDNode::get(Context, &Op, 1)); + } + } + + 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(); + + // 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 (D && isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(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->second; + + if (Ty->isVariablyModifiedType()) + EmitVLASize(Ty); + } +} + +void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) { + const FunctionDecl *FD = cast<FunctionDecl>(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<llvm::CallInst>(&*BI)) + if (!Call->doesNotThrow()) + return; + F->setDoesNotThrow(true); +} + +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; + QualType ResTy = FD->getResultType(); + + CurGD = GD; + if (isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isInstance()) + CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args); + + 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, ResTy, 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()); + + // 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; + 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_range I = S->children(); I; ++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() == BO_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"); + + 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; + } else 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. + 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"); + + 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<UnaryOperator>(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<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"); + + 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<CharUnits,CharUnits> baseSizeAndAlign + = CGF.getContext().getTypeInfoInChars(baseType); + + CGBuilderTy &Builder = CGF.Builder; + + llvm::Value *baseSizeInChars + = llvm::ConstantInt::get(CGF.IntPtrTy, baseSizeAndAlign.first.getQuantity()); + + const 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, "vla.cur"); + cur->reserveOperandSpace(2); + 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<RecordType>()) { + if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty()) + return; + } + } + + // Cast the dest ptr to the appropriate i8 pointer type. + unsigned DestAS = + cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace(); + const 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<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); + uint64_t Size = TypeInfo.first / 8; + unsigned Align = TypeInfo.second / 8; + + llvm::Value *SizeVal; + const VariableArrayType *vla; + + // Don't bother emitting a zero-byte memset. + if (Size == 0) { + // But note that getTypeInfo returns 0 for a VLA. + if (const VariableArrayType *vlaType = + dyn_cast_or_null<VariableArrayType>( + getContext().getAsArrayType(Ty))) { + SizeVal = GetVLASize(vlaType); + vla = vlaType; + } else { + return; + } + } else { + SizeVal = llvm::ConstantInt::get(IntPtrTy, 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, llvm::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, 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, 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, "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)) { + // unknown size indication requires no size computation. + if (!VAT->getSizeExpr()) + return 0; + 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; + } + + if (const ParenType *PT = dyn_cast<ParenType>(Ty)) { + EmitVLASize(PT->getInnerType()); + 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 (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<llvm::ZExtInst>(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(); +} |
