//===--- CodeGenFunction.cpp - Emit LLVM Code from ASTs for a Function ----===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This coordinates the per-function state used while generating code. // //===----------------------------------------------------------------------===// #include "CodeGenFunction.h" #include "CGBlocks.h" #include "CGCleanup.h" #include "CGCUDARuntime.h" #include "CGCXXABI.h" #include "CGDebugInfo.h" #include "CGOpenMPRuntime.h" #include "CodeGenModule.h" #include "CodeGenPGO.h" #include "TargetInfo.h" #include "clang/AST/ASTContext.h" #include "clang/AST/ASTLambda.h" #include "clang/AST/Decl.h" #include "clang/AST/DeclCXX.h" #include "clang/AST/StmtCXX.h" #include "clang/AST/StmtObjC.h" #include "clang/Basic/Builtins.h" #include "clang/Basic/CodeGenOptions.h" #include "clang/Basic/TargetInfo.h" #include "clang/CodeGen/CGFunctionInfo.h" #include "clang/Frontend/FrontendDiagnostic.h" #include "llvm/IR/DataLayout.h" #include "llvm/IR/Dominators.h" #include "llvm/IR/Intrinsics.h" #include "llvm/IR/MDBuilder.h" #include "llvm/IR/Operator.h" #include "llvm/Transforms/Utils/PromoteMemToReg.h" using namespace clang; using namespace CodeGen; /// shouldEmitLifetimeMarkers - Decide whether we need emit the life-time /// markers. static bool shouldEmitLifetimeMarkers(const CodeGenOptions &CGOpts, const LangOptions &LangOpts) { if (CGOpts.DisableLifetimeMarkers) return false; // Disable lifetime markers in msan builds. // FIXME: Remove this when msan works with lifetime markers. if (LangOpts.Sanitize.has(SanitizerKind::Memory)) return false; // Asan uses markers for use-after-scope checks. if (CGOpts.SanitizeAddressUseAfterScope) return true; // For now, only in optimized builds. return CGOpts.OptimizationLevel != 0; } CodeGenFunction::CodeGenFunction(CodeGenModule &cgm, bool suppressNewContext) : CodeGenTypeCache(cgm), CGM(cgm), Target(cgm.getTarget()), Builder(cgm, cgm.getModule().getContext(), llvm::ConstantFolder(), CGBuilderInserterTy(this)), SanOpts(CGM.getLangOpts().Sanitize), DebugInfo(CGM.getModuleDebugInfo()), PGO(cgm), ShouldEmitLifetimeMarkers(shouldEmitLifetimeMarkers( CGM.getCodeGenOpts(), CGM.getLangOpts())) { if (!suppressNewContext) CGM.getCXXABI().getMangleContext().startNewFunction(); llvm::FastMathFlags FMF; if (CGM.getLangOpts().FastMath) FMF.setFast(); if (CGM.getLangOpts().FiniteMathOnly) { FMF.setNoNaNs(); FMF.setNoInfs(); } if (CGM.getCodeGenOpts().NoNaNsFPMath) { FMF.setNoNaNs(); } if (CGM.getCodeGenOpts().NoSignedZeros) { FMF.setNoSignedZeros(); } if (CGM.getCodeGenOpts().ReciprocalMath) { FMF.setAllowReciprocal(); } if (CGM.getCodeGenOpts().Reassociate) { FMF.setAllowReassoc(); } Builder.setFastMathFlags(FMF); } CodeGenFunction::~CodeGenFunction() { assert(LifetimeExtendedCleanupStack.empty() && "failed to emit a cleanup"); // If there are any unclaimed block infos, go ahead and destroy them // now. This can happen if IR-gen gets clever and skips evaluating // something. if (FirstBlockInfo) destroyBlockInfos(FirstBlockInfo); if (getLangOpts().OpenMP && CurFn) CGM.getOpenMPRuntime().functionFinished(*this); } CharUnits CodeGenFunction::getNaturalPointeeTypeAlignment(QualType T, LValueBaseInfo *BaseInfo, TBAAAccessInfo *TBAAInfo) { return getNaturalTypeAlignment(T->getPointeeType(), BaseInfo, TBAAInfo, /* forPointeeType= */ true); } CharUnits CodeGenFunction::getNaturalTypeAlignment(QualType T, LValueBaseInfo *BaseInfo, TBAAAccessInfo *TBAAInfo, bool forPointeeType) { if (TBAAInfo) *TBAAInfo = CGM.getTBAAAccessInfo(T); // Honor alignment typedef attributes even on incomplete types. // We also honor them straight for C++ class types, even as pointees; // there's an expressivity gap here. if (auto TT = T->getAs()) { if (auto Align = TT->getDecl()->getMaxAlignment()) { if (BaseInfo) *BaseInfo = LValueBaseInfo(AlignmentSource::AttributedType); return getContext().toCharUnitsFromBits(Align); } } if (BaseInfo) *BaseInfo = LValueBaseInfo(AlignmentSource::Type); CharUnits Alignment; if (T->isIncompleteType()) { Alignment = CharUnits::One(); // Shouldn't be used, but pessimistic is best. } else { // For C++ class pointees, we don't know whether we're pointing at a // base or a complete object, so we generally need to use the // non-virtual alignment. const CXXRecordDecl *RD; if (forPointeeType && (RD = T->getAsCXXRecordDecl())) { Alignment = CGM.getClassPointerAlignment(RD); } else { Alignment = getContext().getTypeAlignInChars(T); if (T.getQualifiers().hasUnaligned()) Alignment = CharUnits::One(); } // Cap to the global maximum type alignment unless the alignment // was somehow explicit on the type. if (unsigned MaxAlign = getLangOpts().MaxTypeAlign) { if (Alignment.getQuantity() > MaxAlign && !getContext().isAlignmentRequired(T)) Alignment = CharUnits::fromQuantity(MaxAlign); } } return Alignment; } LValue CodeGenFunction::MakeNaturalAlignAddrLValue(llvm::Value *V, QualType T) { LValueBaseInfo BaseInfo; TBAAAccessInfo TBAAInfo; CharUnits Alignment = getNaturalTypeAlignment(T, &BaseInfo, &TBAAInfo); return LValue::MakeAddr(Address(V, Alignment), T, getContext(), BaseInfo, TBAAInfo); } /// Given a value of type T* that may not be to a complete object, /// construct an l-value with the natural pointee alignment of T. LValue CodeGenFunction::MakeNaturalAlignPointeeAddrLValue(llvm::Value *V, QualType T) { LValueBaseInfo BaseInfo; TBAAAccessInfo TBAAInfo; CharUnits Align = getNaturalTypeAlignment(T, &BaseInfo, &TBAAInfo, /* forPointeeType= */ true); return MakeAddrLValue(Address(V, Align), T, BaseInfo, TBAAInfo); } llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) { return CGM.getTypes().ConvertTypeForMem(T); } llvm::Type *CodeGenFunction::ConvertType(QualType T) { return CGM.getTypes().ConvertType(T); } TypeEvaluationKind CodeGenFunction::getEvaluationKind(QualType type) { type = type.getCanonicalType(); while (true) { switch (type->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::Auto: case Type::DeducedTemplateSpecialization: llvm_unreachable("undeduced type in IR-generation"); // Various scalar types. 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: case Type::Pipe: return TEK_Scalar; // Complexes. case Type::Complex: return TEK_Complex; // Arrays, records, and Objective-C objects. case Type::ConstantArray: case Type::IncompleteArray: case Type::VariableArray: case Type::Record: case Type::ObjCObject: case Type::ObjCInterface: return TEK_Aggregate; // We operate on atomic values according to their underlying type. case Type::Atomic: type = cast(type)->getValueType(); continue; } llvm_unreachable("unknown type kind!"); } } llvm::DebugLoc 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(); ReturnBlock = JumpDest(); } else EmitBlock(ReturnBlock.getBlock()); return llvm::DebugLoc(); } // 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()->user_begin()); if (BI && BI->isUnconditional() && BI->getSuccessor(0) == ReturnBlock.getBlock()) { // Record/return the DebugLoc of the simple 'return' expression to be used // later by the actual 'ret' instruction. llvm::DebugLoc Loc = BI->getDebugLoc(); Builder.SetInsertPoint(BI->getParent()); BI->eraseFromParent(); delete ReturnBlock.getBlock(); ReturnBlock = JumpDest(); return Loc; } } // 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()); return llvm::DebugLoc(); } 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!"); bool OnlySimpleReturnStmts = NumSimpleReturnExprs > 0 && NumSimpleReturnExprs == NumReturnExprs && ReturnBlock.getBlock()->use_empty(); // Usually the return expression is evaluated before the cleanup // code. If the function contains only a simple return statement, // such as a constant, the location before the cleanup code becomes // the last useful breakpoint in the function, because the simple // return expression will be evaluated after the cleanup code. To be // safe, set the debug location for cleanup code to the location of // the return statement. Otherwise the cleanup code should be at the // end of the function's lexical scope. // // If there are multiple branches to the return block, the branch // instructions will get the location of the return statements and // all will be fine. if (CGDebugInfo *DI = getDebugInfo()) { if (OnlySimpleReturnStmts) DI->EmitLocation(Builder, LastStopPoint); else DI->EmitLocation(Builder, EndLoc); } // 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. bool HasCleanups = EHStack.stable_begin() != PrologueCleanupDepth; bool HasOnlyLifetimeMarkers = HasCleanups && EHStack.containsOnlyLifetimeMarkers(PrologueCleanupDepth); bool EmitRetDbgLoc = !HasCleanups || HasOnlyLifetimeMarkers; if (HasCleanups) { // Make sure the line table doesn't jump back into the body for // the ret after it's been at EndLoc. if (CGDebugInfo *DI = getDebugInfo()) if (OnlySimpleReturnStmts) DI->EmitLocation(Builder, EndLoc); PopCleanupBlocks(PrologueCleanupDepth); } // Emit function epilog (to return). llvm::DebugLoc Loc = EmitReturnBlock(); if (ShouldInstrumentFunction()) { if (CGM.getCodeGenOpts().InstrumentFunctions) CurFn->addFnAttr("instrument-function-exit", "__cyg_profile_func_exit"); if (CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining) CurFn->addFnAttr("instrument-function-exit-inlined", "__cyg_profile_func_exit"); } // Emit debug descriptor for function end. if (CGDebugInfo *DI = getDebugInfo()) DI->EmitFunctionEnd(Builder, CurFn); // Reset the debug location to that of the simple 'return' expression, if any // rather than that of the end of the function's scope '}'. ApplyDebugLocation AL(*this, Loc); EmitFunctionEpilog(*CurFnInfo, EmitRetDbgLoc, EndLoc); 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(); } // If some of our locals escaped, insert a call to llvm.localescape in the // entry block. if (!EscapedLocals.empty()) { // Invert the map from local to index into a simple vector. There should be // no holes. SmallVector EscapeArgs; EscapeArgs.resize(EscapedLocals.size()); for (auto &Pair : EscapedLocals) EscapeArgs[Pair.second] = Pair.first; llvm::Function *FrameEscapeFn = llvm::Intrinsic::getDeclaration( &CGM.getModule(), llvm::Intrinsic::localescape); CGBuilderTy(*this, AllocaInsertPt).CreateCall(FrameEscapeFn, EscapeArgs); } // Remove the AllocaInsertPt instruction, which is just a convenience for us. llvm::Instruction *Ptr = AllocaInsertPt; AllocaInsertPt = nullptr; 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); for (const auto &FuncletAndParent : TerminateFunclets) EmitIfUsed(*this, FuncletAndParent.second); if (CGM.getCodeGenOpts().EmitDeclMetadata) EmitDeclMetadata(); for (SmallVectorImpl >::iterator I = DeferredReplacements.begin(), E = DeferredReplacements.end(); I != E; ++I) { I->first->replaceAllUsesWith(I->second); I->first->eraseFromParent(); } // Eliminate CleanupDestSlot alloca by replacing it with SSA values and // PHIs if the current function is a coroutine. We don't do it for all // functions as it may result in slight increase in numbers of instructions // if compiled with no optimizations. We do it for coroutine as the lifetime // of CleanupDestSlot alloca make correct coroutine frame building very // difficult. if (NormalCleanupDest.isValid() && isCoroutine()) { llvm::DominatorTree DT(*CurFn); llvm::PromoteMemToReg( cast(NormalCleanupDest.getPointer()), DT); NormalCleanupDest = Address::invalid(); } // Scan function arguments for vector width. for (llvm::Argument &A : CurFn->args()) if (auto *VT = dyn_cast(A.getType())) LargestVectorWidth = std::max(LargestVectorWidth, VT->getPrimitiveSizeInBits()); // Update vector width based on return type. if (auto *VT = dyn_cast(CurFn->getReturnType())) LargestVectorWidth = std::max(LargestVectorWidth, VT->getPrimitiveSizeInBits()); // Add the required-vector-width attribute. This contains the max width from: // 1. min-vector-width attribute used in the source program. // 2. Any builtins used that have a vector width specified. // 3. Values passed in and out of inline assembly. // 4. Width of vector arguments and return types for this function. // 5. Width of vector aguments and return types for functions called by this // function. CurFn->addFnAttr("min-legal-vector-width", llvm::utostr(LargestVectorWidth)); // If we generated an unreachable return block, delete it now. if (ReturnBlock.isValid() && ReturnBlock.getBlock()->use_empty()) { Builder.ClearInsertionPoint(); ReturnBlock.getBlock()->eraseFromParent(); } if (ReturnValue.isValid()) { auto *RetAlloca = dyn_cast(ReturnValue.getPointer()); if (RetAlloca && RetAlloca->use_empty()) { RetAlloca->eraseFromParent(); ReturnValue = Address::invalid(); } } } /// ShouldInstrumentFunction - Return true if the current function should be /// instrumented with __cyg_profile_func_* calls bool CodeGenFunction::ShouldInstrumentFunction() { if (!CGM.getCodeGenOpts().InstrumentFunctions && !CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining && !CGM.getCodeGenOpts().InstrumentFunctionEntryBare) return false; if (!CurFuncDecl || CurFuncDecl->hasAttr()) return false; return true; } /// ShouldXRayInstrument - Return true if the current function should be /// instrumented with XRay nop sleds. bool CodeGenFunction::ShouldXRayInstrumentFunction() const { return CGM.getCodeGenOpts().XRayInstrumentFunctions; } /// AlwaysEmitXRayCustomEvents - Return true if we should emit IR for calls to /// the __xray_customevent(...) builtin calls, when doing XRay instrumentation. bool CodeGenFunction::AlwaysEmitXRayCustomEvents() const { return CGM.getCodeGenOpts().XRayInstrumentFunctions && (CGM.getCodeGenOpts().XRayAlwaysEmitCustomEvents || CGM.getCodeGenOpts().XRayInstrumentationBundle.Mask == XRayInstrKind::Custom); } bool CodeGenFunction::AlwaysEmitXRayTypedEvents() const { return CGM.getCodeGenOpts().XRayInstrumentFunctions && (CGM.getCodeGenOpts().XRayAlwaysEmitTypedEvents || CGM.getCodeGenOpts().XRayInstrumentationBundle.Mask == XRayInstrKind::Typed); } llvm::Constant * CodeGenFunction::EncodeAddrForUseInPrologue(llvm::Function *F, llvm::Constant *Addr) { // Addresses stored in prologue data can't require run-time fixups and must // be PC-relative. Run-time fixups are undesirable because they necessitate // writable text segments, which are unsafe. And absolute addresses are // undesirable because they break PIE mode. // Add a layer of indirection through a private global. Taking its address // won't result in a run-time fixup, even if Addr has linkonce_odr linkage. auto *GV = new llvm::GlobalVariable(CGM.getModule(), Addr->getType(), /*isConstant=*/true, llvm::GlobalValue::PrivateLinkage, Addr); // Create a PC-relative address. auto *GOTAsInt = llvm::ConstantExpr::getPtrToInt(GV, IntPtrTy); auto *FuncAsInt = llvm::ConstantExpr::getPtrToInt(F, IntPtrTy); auto *PCRelAsInt = llvm::ConstantExpr::getSub(GOTAsInt, FuncAsInt); return (IntPtrTy == Int32Ty) ? PCRelAsInt : llvm::ConstantExpr::getTrunc(PCRelAsInt, Int32Ty); } llvm::Value * CodeGenFunction::DecodeAddrUsedInPrologue(llvm::Value *F, llvm::Value *EncodedAddr) { // Reconstruct the address of the global. auto *PCRelAsInt = Builder.CreateSExt(EncodedAddr, IntPtrTy); auto *FuncAsInt = Builder.CreatePtrToInt(F, IntPtrTy, "func_addr.int"); auto *GOTAsInt = Builder.CreateAdd(PCRelAsInt, FuncAsInt, "global_addr.int"); auto *GOTAddr = Builder.CreateIntToPtr(GOTAsInt, Int8PtrPtrTy, "global_addr"); // Load the original pointer through the global. return Builder.CreateLoad(Address(GOTAddr, getPointerAlign()), "decoded_addr"); } void CodeGenFunction::EmitOpenCLKernelMetadata(const FunctionDecl *FD, llvm::Function *Fn) { if (!FD->hasAttr()) return; llvm::LLVMContext &Context = getLLVMContext(); CGM.GenOpenCLArgMetadata(Fn, FD, this); if (const VecTypeHintAttr *A = FD->getAttr()) { QualType HintQTy = A->getTypeHint(); const ExtVectorType *HintEltQTy = HintQTy->getAs(); bool IsSignedInteger = HintQTy->isSignedIntegerType() || (HintEltQTy && HintEltQTy->getElementType()->isSignedIntegerType()); llvm::Metadata *AttrMDArgs[] = { llvm::ConstantAsMetadata::get(llvm::UndefValue::get( CGM.getTypes().ConvertType(A->getTypeHint()))), llvm::ConstantAsMetadata::get(llvm::ConstantInt::get( llvm::IntegerType::get(Context, 32), llvm::APInt(32, (uint64_t)(IsSignedInteger ? 1 : 0))))}; Fn->setMetadata("vec_type_hint", llvm::MDNode::get(Context, AttrMDArgs)); } if (const WorkGroupSizeHintAttr *A = FD->getAttr()) { llvm::Metadata *AttrMDArgs[] = { llvm::ConstantAsMetadata::get(Builder.getInt32(A->getXDim())), llvm::ConstantAsMetadata::get(Builder.getInt32(A->getYDim())), llvm::ConstantAsMetadata::get(Builder.getInt32(A->getZDim()))}; Fn->setMetadata("work_group_size_hint", llvm::MDNode::get(Context, AttrMDArgs)); } if (const ReqdWorkGroupSizeAttr *A = FD->getAttr()) { llvm::Metadata *AttrMDArgs[] = { llvm::ConstantAsMetadata::get(Builder.getInt32(A->getXDim())), llvm::ConstantAsMetadata::get(Builder.getInt32(A->getYDim())), llvm::ConstantAsMetadata::get(Builder.getInt32(A->getZDim()))}; Fn->setMetadata("reqd_work_group_size", llvm::MDNode::get(Context, AttrMDArgs)); } if (const OpenCLIntelReqdSubGroupSizeAttr *A = FD->getAttr()) { llvm::Metadata *AttrMDArgs[] = { llvm::ConstantAsMetadata::get(Builder.getInt32(A->getSubGroupSize()))}; Fn->setMetadata("intel_reqd_sub_group_size", llvm::MDNode::get(Context, AttrMDArgs)); } } /// Determine whether the function F ends with a return stmt. static bool endsWithReturn(const Decl* F) { const Stmt *Body = nullptr; if (auto *FD = dyn_cast_or_null(F)) Body = FD->getBody(); else if (auto *OMD = dyn_cast_or_null(F)) Body = OMD->getBody(); if (auto *CS = dyn_cast_or_null(Body)) { auto LastStmt = CS->body_rbegin(); if (LastStmt != CS->body_rend()) return isa(*LastStmt); } return false; } void CodeGenFunction::markAsIgnoreThreadCheckingAtRuntime(llvm::Function *Fn) { if (SanOpts.has(SanitizerKind::Thread)) { Fn->addFnAttr("sanitize_thread_no_checking_at_run_time"); Fn->removeFnAttr(llvm::Attribute::SanitizeThread); } } static bool matchesStlAllocatorFn(const Decl *D, const ASTContext &Ctx) { auto *MD = dyn_cast_or_null(D); if (!MD || !MD->getDeclName().getAsIdentifierInfo() || !MD->getDeclName().getAsIdentifierInfo()->isStr("allocate") || (MD->getNumParams() != 1 && MD->getNumParams() != 2)) return false; if (MD->parameters()[0]->getType().getCanonicalType() != Ctx.getSizeType()) return false; if (MD->getNumParams() == 2) { auto *PT = MD->parameters()[1]->getType()->getAs(); if (!PT || !PT->isVoidPointerType() || !PT->getPointeeType().isConstQualified()) return false; } return true; } /// Return the UBSan prologue signature for \p FD if one is available. static llvm::Constant *getPrologueSignature(CodeGenModule &CGM, const FunctionDecl *FD) { if (const auto *MD = dyn_cast(FD)) if (!MD->isStatic()) return nullptr; return CGM.getTargetCodeGenInfo().getUBSanFunctionSignature(CGM); } void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy, llvm::Function *Fn, const CGFunctionInfo &FnInfo, const FunctionArgList &Args, SourceLocation Loc, SourceLocation StartLoc) { assert(!CurFn && "Do not use a CodeGenFunction object for more than one function"); const Decl *D = GD.getDecl(); DidCallStackSave = false; CurCodeDecl = D; if (const auto *FD = dyn_cast_or_null(D)) if (FD->usesSEHTry()) CurSEHParent = FD; CurFuncDecl = (D ? D->getNonClosureContext() : nullptr); FnRetTy = RetTy; CurFn = Fn; CurFnInfo = &FnInfo; assert(CurFn->isDeclaration() && "Function already has body?"); // If this function has been blacklisted for any of the enabled sanitizers, // disable the sanitizer for the function. do { #define SANITIZER(NAME, ID) \ if (SanOpts.empty()) \ break; \ if (SanOpts.has(SanitizerKind::ID)) \ if (CGM.isInSanitizerBlacklist(SanitizerKind::ID, Fn, Loc)) \ SanOpts.set(SanitizerKind::ID, false); #include "clang/Basic/Sanitizers.def" #undef SANITIZER } while (0); if (D) { // Apply the no_sanitize* attributes to SanOpts. for (auto Attr : D->specific_attrs()) { SanitizerMask mask = Attr->getMask(); SanOpts.Mask &= ~mask; if (mask & SanitizerKind::Address) SanOpts.set(SanitizerKind::KernelAddress, false); if (mask & SanitizerKind::KernelAddress) SanOpts.set(SanitizerKind::Address, false); if (mask & SanitizerKind::HWAddress) SanOpts.set(SanitizerKind::KernelHWAddress, false); if (mask & SanitizerKind::KernelHWAddress) SanOpts.set(SanitizerKind::HWAddress, false); } } // Apply sanitizer attributes to the function. if (SanOpts.hasOneOf(SanitizerKind::Address | SanitizerKind::KernelAddress)) Fn->addFnAttr(llvm::Attribute::SanitizeAddress); if (SanOpts.hasOneOf(SanitizerKind::HWAddress | SanitizerKind::KernelHWAddress)) Fn->addFnAttr(llvm::Attribute::SanitizeHWAddress); if (SanOpts.has(SanitizerKind::MemTag)) Fn->addFnAttr(llvm::Attribute::SanitizeMemTag); if (SanOpts.has(SanitizerKind::Thread)) Fn->addFnAttr(llvm::Attribute::SanitizeThread); if (SanOpts.hasOneOf(SanitizerKind::Memory | SanitizerKind::KernelMemory)) Fn->addFnAttr(llvm::Attribute::SanitizeMemory); if (SanOpts.has(SanitizerKind::SafeStack)) Fn->addFnAttr(llvm::Attribute::SafeStack); if (SanOpts.has(SanitizerKind::ShadowCallStack)) Fn->addFnAttr(llvm::Attribute::ShadowCallStack); // Apply fuzzing attribute to the function. if (SanOpts.hasOneOf(SanitizerKind::Fuzzer | SanitizerKind::FuzzerNoLink)) Fn->addFnAttr(llvm::Attribute::OptForFuzzing); // Ignore TSan memory acesses from within ObjC/ObjC++ dealloc, initialize, // .cxx_destruct, __destroy_helper_block_ and all of their calees at run time. if (SanOpts.has(SanitizerKind::Thread)) { if (const auto *OMD = dyn_cast_or_null(D)) { IdentifierInfo *II = OMD->getSelector().getIdentifierInfoForSlot(0); if (OMD->getMethodFamily() == OMF_dealloc || OMD->getMethodFamily() == OMF_initialize || (OMD->getSelector().isUnarySelector() && II->isStr(".cxx_destruct"))) { markAsIgnoreThreadCheckingAtRuntime(Fn); } } } // Ignore unrelated casts in STL allocate() since the allocator must cast // from void* to T* before object initialization completes. Don't match on the // namespace because not all allocators are in std:: if (D && SanOpts.has(SanitizerKind::CFIUnrelatedCast)) { if (matchesStlAllocatorFn(D, getContext())) SanOpts.Mask &= ~SanitizerKind::CFIUnrelatedCast; } // Apply xray attributes to the function (as a string, for now) if (D) { if (const auto *XRayAttr = D->getAttr()) { if (CGM.getCodeGenOpts().XRayInstrumentationBundle.has( XRayInstrKind::Function)) { if (XRayAttr->alwaysXRayInstrument() && ShouldXRayInstrumentFunction()) Fn->addFnAttr("function-instrument", "xray-always"); if (XRayAttr->neverXRayInstrument()) Fn->addFnAttr("function-instrument", "xray-never"); if (const auto *LogArgs = D->getAttr()) if (ShouldXRayInstrumentFunction()) Fn->addFnAttr("xray-log-args", llvm::utostr(LogArgs->getArgumentCount())); } } else { if (ShouldXRayInstrumentFunction() && !CGM.imbueXRayAttrs(Fn, Loc)) Fn->addFnAttr( "xray-instruction-threshold", llvm::itostr(CGM.getCodeGenOpts().XRayInstructionThreshold)); } } // Add no-jump-tables value. Fn->addFnAttr("no-jump-tables", llvm::toStringRef(CGM.getCodeGenOpts().NoUseJumpTables)); // Add profile-sample-accurate value. if (CGM.getCodeGenOpts().ProfileSampleAccurate) Fn->addFnAttr("profile-sample-accurate"); if (getLangOpts().OpenCL) { // Add metadata for a kernel function. if (const FunctionDecl *FD = dyn_cast_or_null(D)) EmitOpenCLKernelMetadata(FD, Fn); } // If we are checking function types, emit a function type signature as // prologue data. if (getLangOpts().CPlusPlus && SanOpts.has(SanitizerKind::Function)) { if (const FunctionDecl *FD = dyn_cast_or_null(D)) { if (llvm::Constant *PrologueSig = getPrologueSignature(CGM, FD)) { // Remove any (C++17) exception specifications, to allow calling e.g. a // noexcept function through a non-noexcept pointer. auto ProtoTy = getContext().getFunctionTypeWithExceptionSpec(FD->getType(), EST_None); llvm::Constant *FTRTTIConst = CGM.GetAddrOfRTTIDescriptor(ProtoTy, /*ForEH=*/true); llvm::Constant *FTRTTIConstEncoded = EncodeAddrForUseInPrologue(Fn, FTRTTIConst); llvm::Constant *PrologueStructElems[] = {PrologueSig, FTRTTIConstEncoded}; llvm::Constant *PrologueStructConst = llvm::ConstantStruct::getAnon(PrologueStructElems, /*Packed=*/true); Fn->setPrologueData(PrologueStructConst); } } } // If we're checking nullability, we need to know whether we can check the // return value. Initialize the flag to 'true' and refine it in EmitParmDecl. if (SanOpts.has(SanitizerKind::NullabilityReturn)) { auto Nullability = FnRetTy->getNullability(getContext()); if (Nullability && *Nullability == NullabilityKind::NonNull) { if (!(SanOpts.has(SanitizerKind::ReturnsNonnullAttribute) && CurCodeDecl && CurCodeDecl->getAttr())) RetValNullabilityPrecondition = llvm::ConstantInt::getTrue(getLLVMContext()); } } // If we're in C++ mode and the function name is "main", it is guaranteed // to be norecurse by the standard (3.6.1.3 "The function main shall not be // used within a program"). if (getLangOpts().CPlusPlus) if (const FunctionDecl *FD = dyn_cast_or_null(D)) if (FD->isMain()) Fn->addFnAttr(llvm::Attribute::NoRecurse); // If a custom alignment is used, force realigning to this alignment on // any main function which certainly will need it. if (const FunctionDecl *FD = dyn_cast_or_null(D)) if ((FD->isMain() || FD->isMSVCRTEntryPoint()) && CGM.getCodeGenOpts().StackAlignment) Fn->addFnAttr("stackrealign"); 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, "allocapt", EntryBB); ReturnBlock = getJumpDestInCurrentScope("return"); Builder.SetInsertPoint(EntryBB); // If we're checking the return value, allocate space for a pointer to a // precise source location of the checked return statement. if (requiresReturnValueCheck()) { ReturnLocation = CreateDefaultAlignTempAlloca(Int8PtrTy, "return.sloc.ptr"); InitTempAlloca(ReturnLocation, llvm::ConstantPointerNull::get(Int8PtrTy)); } // Emit subprogram debug descriptor. if (CGDebugInfo *DI = getDebugInfo()) { // Reconstruct the type from the argument list so that implicit parameters, // such as 'this' and 'vtt', show up in the debug info. Preserve the calling // convention. CallingConv CC = CallingConv::CC_C; if (auto *FD = dyn_cast_or_null(D)) if (const auto *SrcFnTy = FD->getType()->getAs()) CC = SrcFnTy->getCallConv(); SmallVector ArgTypes; for (const VarDecl *VD : Args) ArgTypes.push_back(VD->getType()); QualType FnType = getContext().getFunctionType( RetTy, ArgTypes, FunctionProtoType::ExtProtoInfo(CC)); DI->EmitFunctionStart(GD, Loc, StartLoc, FnType, CurFn, CurFuncIsThunk, Builder); } if (ShouldInstrumentFunction()) { if (CGM.getCodeGenOpts().InstrumentFunctions) CurFn->addFnAttr("instrument-function-entry", "__cyg_profile_func_enter"); if (CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining) CurFn->addFnAttr("instrument-function-entry-inlined", "__cyg_profile_func_enter"); if (CGM.getCodeGenOpts().InstrumentFunctionEntryBare) CurFn->addFnAttr("instrument-function-entry-inlined", "__cyg_profile_func_enter_bare"); } // Since emitting the mcount call here impacts optimizations such as function // inlining, we just add an attribute to insert a mcount call in backend. // The attribute "counting-function" is set to mcount function name which is // architecture dependent. if (CGM.getCodeGenOpts().InstrumentForProfiling) { // Calls to fentry/mcount should not be generated if function has // the no_instrument_function attribute. if (!CurFuncDecl || !CurFuncDecl->hasAttr()) { if (CGM.getCodeGenOpts().CallFEntry) Fn->addFnAttr("fentry-call", "true"); else { Fn->addFnAttr("instrument-function-entry-inlined", getTarget().getMCountName()); } } } if (RetTy->isVoidType()) { // Void type; nothing to return. ReturnValue = Address::invalid(); // Count the implicit return. if (!endsWithReturn(D)) ++NumReturnExprs; } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect) { // Indirect return; emit returned value directly into sret slot. // This reduces code size, and affects correctness in C++. auto AI = CurFn->arg_begin(); if (CurFnInfo->getReturnInfo().isSRetAfterThis()) ++AI; ReturnValue = Address(&*AI, CurFnInfo->getReturnInfo().getIndirectAlign()); if (!CurFnInfo->getReturnInfo().getIndirectByVal()) { ReturnValuePointer = CreateDefaultAlignTempAlloca(Int8PtrTy, "result.ptr"); Builder.CreateStore(Builder.CreatePointerBitCastOrAddrSpaceCast( ReturnValue.getPointer(), Int8PtrTy), ReturnValuePointer); } } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::InAlloca && !hasScalarEvaluationKind(CurFnInfo->getReturnType())) { // Load the sret pointer from the argument struct and return into that. unsigned Idx = CurFnInfo->getReturnInfo().getInAllocaFieldIndex(); llvm::Function::arg_iterator EI = CurFn->arg_end(); --EI; llvm::Value *Addr = Builder.CreateStructGEP(nullptr, &*EI, Idx); ReturnValuePointer = Address(Addr, getPointerAlign()); Addr = Builder.CreateAlignedLoad(Addr, getPointerAlign(), "agg.result"); ReturnValue = Address(Addr, getNaturalTypeAlignment(RetTy)); } 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 (getLangOpts().ObjCAutoRefCount && !CurFnInfo->isReturnsRetained() && RetTy->isObjCRetainableType()) AutoreleaseResult = true; } EmitStartEHSpec(CurCodeDecl); PrologueCleanupDepth = EHStack.stable_begin(); // Emit OpenMP specific initialization of the device functions. if (getLangOpts().OpenMP && CurCodeDecl) CGM.getOpenMPRuntime().emitFunctionProlog(*this, CurCodeDecl); EmitFunctionProlog(*CurFnInfo, CurFn, Args); if (D && isa(D) && cast(D)->isInstance()) { CGM.getCXXABI().EmitInstanceFunctionProlog(*this); const CXXMethodDecl *MD = cast(D); if (MD->getParent()->isLambda() && MD->getOverloadedOperator() == OO_Call) { // We're in a lambda; figure out the captures. MD->getParent()->getCaptureFields(LambdaCaptureFields, LambdaThisCaptureField); if (LambdaThisCaptureField) { // If the lambda captures the object referred to by '*this' - either by // value or by reference, make sure CXXThisValue points to the correct // object. // Get the lvalue for the field (which is a copy of the enclosing object // or contains the address of the enclosing object). LValue ThisFieldLValue = EmitLValueForLambdaField(LambdaThisCaptureField); if (!LambdaThisCaptureField->getType()->isPointerType()) { // If the enclosing object was captured by value, just use its address. CXXThisValue = ThisFieldLValue.getAddress().getPointer(); } else { // Load the lvalue pointed to by the field, since '*this' was captured // by reference. CXXThisValue = EmitLoadOfLValue(ThisFieldLValue, SourceLocation()).getScalarVal(); } } for (auto *FD : MD->getParent()->fields()) { if (FD->hasCapturedVLAType()) { auto *ExprArg = EmitLoadOfLValue(EmitLValueForLambdaField(FD), SourceLocation()).getScalarVal(); auto VAT = FD->getCapturedVLAType(); VLASizeMap[VAT->getSizeExpr()] = ExprArg; } } } else { // Not in a lambda; just use 'this' from the method. // FIXME: Should we generate a new load for each use of 'this'? The // fast register allocator would be happier... CXXThisValue = CXXABIThisValue; } // Check the 'this' pointer once per function, if it's available. if (CXXABIThisValue) { SanitizerSet SkippedChecks; SkippedChecks.set(SanitizerKind::ObjectSize, true); QualType ThisTy = MD->getThisType(); // If this is the call operator of a lambda with no capture-default, it // may have a static invoker function, which may call this operator with // a null 'this' pointer. if (isLambdaCallOperator(MD) && MD->getParent()->getLambdaCaptureDefault() == LCD_None) SkippedChecks.set(SanitizerKind::Null, true); EmitTypeCheck(isa(MD) ? TCK_ConstructorCall : TCK_MemberCall, Loc, CXXABIThisValue, ThisTy, getContext().getTypeAlignInChars(ThisTy->getPointeeType()), SkippedChecks); } } // 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) { const VarDecl *VD = *i; // Dig out the type as written from ParmVarDecls; it's unclear whether // the standard (C99 6.9.1p10) requires this, but we're following the // precedent set by gcc. QualType Ty; if (const ParmVarDecl *PVD = dyn_cast(VD)) Ty = PVD->getOriginalType(); else Ty = VD->getType(); if (Ty->isVariablyModifiedType()) EmitVariablyModifiedType(Ty); } // Emit a location at the end of the prologue. if (CGDebugInfo *DI = getDebugInfo()) DI->EmitLocation(Builder, StartLoc); // TODO: Do we need to handle this in two places like we do with // target-features/target-cpu? if (CurFuncDecl) if (const auto *VecWidth = CurFuncDecl->getAttr()) LargestVectorWidth = VecWidth->getVectorWidth(); } void CodeGenFunction::EmitFunctionBody(const Stmt *Body) { incrementProfileCounter(Body); if (const CompoundStmt *S = dyn_cast(Body)) EmitCompoundStmtWithoutScope(*S); else EmitStmt(Body); } /// When instrumenting to collect profile data, the counts for some blocks /// such as switch cases need to not include the fall-through counts, so /// emit a branch around the instrumentation code. When not instrumenting, /// this just calls EmitBlock(). void CodeGenFunction::EmitBlockWithFallThrough(llvm::BasicBlock *BB, const Stmt *S) { llvm::BasicBlock *SkipCountBB = nullptr; if (HaveInsertPoint() && CGM.getCodeGenOpts().hasProfileClangInstr()) { // When instrumenting for profiling, the fallthrough to certain // statements needs to skip over the instrumentation code so that we // get an accurate count. SkipCountBB = createBasicBlock("skipcount"); EmitBranch(SkipCountBB); } EmitBlock(BB); uint64_t CurrentCount = getCurrentProfileCount(); incrementProfileCounter(S); setCurrentProfileCount(getCurrentProfileCount() + CurrentCount); if (SkipCountBB) EmitBlock(SkipCountBB); } /// 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->isInterposable()) return; for (llvm::BasicBlock &BB : *F) for (llvm::Instruction &I : BB) if (I.mayThrow()) return; F->setDoesNotThrow(); } QualType CodeGenFunction::BuildFunctionArgList(GlobalDecl GD, FunctionArgList &Args) { const FunctionDecl *FD = cast(GD.getDecl()); QualType ResTy = FD->getReturnType(); const CXXMethodDecl *MD = dyn_cast(FD); if (MD && MD->isInstance()) { if (CGM.getCXXABI().HasThisReturn(GD)) ResTy = MD->getThisType(); else if (CGM.getCXXABI().hasMostDerivedReturn(GD)) ResTy = CGM.getContext().VoidPtrTy; CGM.getCXXABI().buildThisParam(*this, Args); } // The base version of an inheriting constructor whose constructed base is a // virtual base is not passed any arguments (because it doesn't actually call // the inherited constructor). bool PassedParams = true; if (const CXXConstructorDecl *CD = dyn_cast(FD)) if (auto Inherited = CD->getInheritedConstructor()) PassedParams = getTypes().inheritingCtorHasParams(Inherited, GD.getCtorType()); if (PassedParams) { for (auto *Param : FD->parameters()) { Args.push_back(Param); if (!Param->hasAttr()) continue; auto *Implicit = ImplicitParamDecl::Create( getContext(), Param->getDeclContext(), Param->getLocation(), /*Id=*/nullptr, getContext().getSizeType(), ImplicitParamDecl::Other); SizeArguments[Param] = Implicit; Args.push_back(Implicit); } } if (MD && (isa(MD) || isa(MD))) CGM.getCXXABI().addImplicitStructorParams(*this, ResTy, Args); return ResTy; } static bool shouldUseUndefinedBehaviorReturnOptimization(const FunctionDecl *FD, const ASTContext &Context) { QualType T = FD->getReturnType(); // Avoid the optimization for functions that return a record type with a // trivial destructor or another trivially copyable type. if (const RecordType *RT = T.getCanonicalType()->getAs()) { if (const auto *ClassDecl = dyn_cast(RT->getDecl())) return !ClassDecl->hasTrivialDestructor(); } return !T.isTriviallyCopyableType(Context); } void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn, const CGFunctionInfo &FnInfo) { const FunctionDecl *FD = cast(GD.getDecl()); CurGD = GD; FunctionArgList Args; QualType ResTy = BuildFunctionArgList(GD, Args); // Check if we should generate debug info for this function. if (FD->hasAttr()) DebugInfo = nullptr; // disable debug info indefinitely for this function // The function might not have a body if we're generating thunks for a // function declaration. SourceRange BodyRange; if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange(); else BodyRange = FD->getLocation(); CurEHLocation = BodyRange.getEnd(); // Use the location of the start of the function to determine where // the function definition is located. By default use the location // of the declaration as the location for the subprogram. A function // may lack a declaration in the source code if it is created by code // gen. (examples: _GLOBAL__I_a, __cxx_global_array_dtor, thunk). SourceLocation Loc = FD->getLocation(); // If this is a function specialization then use the pattern body // as the location for the function. if (const FunctionDecl *SpecDecl = FD->getTemplateInstantiationPattern()) if (SpecDecl->hasBody(SpecDecl)) Loc = SpecDecl->getLocation(); Stmt *Body = FD->getBody(); // Initialize helper which will detect jumps which can cause invalid lifetime // markers. if (Body && ShouldEmitLifetimeMarkers) Bypasses.Init(Body); // Emit the standard function prologue. StartFunction(GD, ResTy, Fn, FnInfo, Args, Loc, BodyRange.getBegin()); // Generate the body of the function. PGO.assignRegionCounters(GD, CurFn); if (isa(FD)) EmitDestructorBody(Args); else if (isa(FD)) EmitConstructorBody(Args); else if (getLangOpts().CUDA && !getLangOpts().CUDAIsDevice && FD->hasAttr()) CGM.getCUDARuntime().emitDeviceStub(*this, Args); else if (isa(FD) && cast(FD)->isLambdaStaticInvoker()) { // The lambda static invoker function is special, because it forwards or // clones the body of the function call operator (but is actually static). EmitLambdaStaticInvokeBody(cast(FD)); } else if (FD->isDefaulted() && isa(FD) && (cast(FD)->isCopyAssignmentOperator() || cast(FD)->isMoveAssignmentOperator())) { // Implicit copy-assignment gets the same special treatment as implicit // copy-constructors. emitImplicitAssignmentOperatorBody(Args); } else if (Body) { EmitFunctionBody(Body); } else llvm_unreachable("no definition for emitted function"); // C++11 [stmt.return]p2: // Flowing off the end of a function [...] results in undefined behavior in // a value-returning function. // C11 6.9.1p12: // If the '}' that terminates a function is reached, and the value of the // function call is used by the caller, the behavior is undefined. if (getLangOpts().CPlusPlus && !FD->hasImplicitReturnZero() && !SawAsmBlock && !FD->getReturnType()->isVoidType() && Builder.GetInsertBlock()) { bool ShouldEmitUnreachable = CGM.getCodeGenOpts().StrictReturn || shouldUseUndefinedBehaviorReturnOptimization(FD, getContext()); if (SanOpts.has(SanitizerKind::Return)) { SanitizerScope SanScope(this); llvm::Value *IsFalse = Builder.getFalse(); EmitCheck(std::make_pair(IsFalse, SanitizerKind::Return), SanitizerHandler::MissingReturn, EmitCheckSourceLocation(FD->getLocation()), None); } else if (ShouldEmitUnreachable) { if (CGM.getCodeGenOpts().OptimizationLevel == 0) EmitTrapCall(llvm::Intrinsic::trap); } if (SanOpts.has(SanitizerKind::Return) || ShouldEmitUnreachable) { Builder.CreateUnreachable(); Builder.ClearInsertionPoint(); } } // 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) 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 (const Stmt *SubStmt : S->children()) if (ContainsLabel(SubStmt, 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) 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 (const Stmt *SubStmt : S->children()) if (containsBreak(SubStmt)) return true; return false; } bool CodeGenFunction::mightAddDeclToScope(const Stmt *S) { if (!S) return false; // Some statement kinds add a scope and thus never add a decl to the current // scope. Note, this list is longer than the list of statements that might // have an unscoped decl nested within them, but this way is conservatively // correct even if more statement kinds are added. if (isa(S) || isa(S) || isa(S) || isa(S) || isa(S) || isa(S) || isa(S) || isa(S) || isa(S) || isa(S)) return false; if (isa(S)) return true; for (const Stmt *SubStmt : S->children()) if (mightAddDeclToScope(SubStmt)) 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, bool AllowLabels) { llvm::APSInt ResultInt; if (!ConstantFoldsToSimpleInteger(Cond, ResultInt, AllowLabels)) 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::APSInt &ResultInt, bool AllowLabels) { // FIXME: Rename and handle conversion of other evaluatable things // to bool. Expr::EvalResult Result; if (!Cond->EvaluateAsInt(Result, getContext())) return false; // Not foldable, not integer or not fully evaluatable. llvm::APSInt Int = Result.Val.getInt(); if (!AllowLabels && CodeGenFunction::ContainsLabel(Cond)) return false; // Contains a label. ResultInt = Int; 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, uint64_t TrueCount) { 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). incrementProfileCounter(CondBOp); return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock, TrueCount); } // 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, TrueCount); } // 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"); // The counter tells us how often we evaluate RHS, and all of TrueCount // can be propagated to that branch. uint64_t RHSCount = getProfileCount(CondBOp->getRHS()); ConditionalEvaluation eval(*this); { ApplyDebugLocation DL(*this, Cond); EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock, RHSCount); EmitBlock(LHSTrue); } incrementProfileCounter(CondBOp); setCurrentProfileCount(getProfileCount(CondBOp->getRHS())); // Any temporaries created here are conditional. eval.begin(*this); EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock, TrueCount); 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). incrementProfileCounter(CondBOp); return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock, TrueCount); } // 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, TrueCount); } // 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"); // We have the count for entry to the RHS and for the whole expression // being true, so we can divy up True count between the short circuit and // the RHS. uint64_t LHSCount = getCurrentProfileCount() - getProfileCount(CondBOp->getRHS()); uint64_t RHSCount = TrueCount - LHSCount; ConditionalEvaluation eval(*this); { ApplyDebugLocation DL(*this, Cond); EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse, LHSCount); EmitBlock(LHSFalse); } incrementProfileCounter(CondBOp); setCurrentProfileCount(getProfileCount(CondBOp->getRHS())); // Any temporaries created here are conditional. eval.begin(*this); EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock, RHSCount); eval.end(*this); return; } } if (const UnaryOperator *CondUOp = dyn_cast(Cond)) { // br(!x, t, f) -> br(x, f, t) if (CondUOp->getOpcode() == UO_LNot) { // Negate the count. uint64_t FalseCount = getCurrentProfileCount() - TrueCount; // Negate the condition and swap the destination blocks. return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock, FalseCount); } } if (const ConditionalOperator *CondOp = dyn_cast(Cond)) { // 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, getProfileCount(CondOp)); // When computing PGO branch weights, we only know the overall count for // the true block. This code is essentially doing tail duplication of the // naive code-gen, introducing new edges for which counts are not // available. Divide the counts proportionally between the LHS and RHS of // the conditional operator. uint64_t LHSScaledTrueCount = 0; if (TrueCount) { double LHSRatio = getProfileCount(CondOp) / (double)getCurrentProfileCount(); LHSScaledTrueCount = TrueCount * LHSRatio; } cond.begin(*this); EmitBlock(LHSBlock); incrementProfileCounter(CondOp); { ApplyDebugLocation DL(*this, Cond); EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock, LHSScaledTrueCount); } cond.end(*this); cond.begin(*this); EmitBlock(RHSBlock); EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock, TrueCount - LHSScaledTrueCount); cond.end(*this); return; } if (const CXXThrowExpr *Throw = dyn_cast(Cond)) { // Conditional operator handling can give us a throw expression as a // condition for a case like: // br(c ? throw x : y, t, f) -> br(c, br(throw x, t, f), br(y, t, f) // Fold this to: // br(c, throw x, br(y, t, f)) EmitCXXThrowExpr(Throw, /*KeepInsertionPoint*/false); return; } // If the branch has a condition wrapped by __builtin_unpredictable, // create metadata that specifies that the branch is unpredictable. // Don't bother if not optimizing because that metadata would not be used. llvm::MDNode *Unpredictable = nullptr; auto *Call = dyn_cast(Cond->IgnoreImpCasts()); if (Call && CGM.getCodeGenOpts().OptimizationLevel != 0) { auto *FD = dyn_cast_or_null(Call->getCalleeDecl()); if (FD && FD->getBuiltinID() == Builtin::BI__builtin_unpredictable) { llvm::MDBuilder MDHelper(getLLVMContext()); Unpredictable = MDHelper.createUnpredictable(); } } // Create branch weights based on the number of times we get here and the // number of times the condition should be true. uint64_t CurrentCount = std::max(getCurrentProfileCount(), TrueCount); llvm::MDNode *Weights = createProfileWeights(TrueCount, CurrentCount - TrueCount); // Emit the code with the fully general case. llvm::Value *CondV; { ApplyDebugLocation DL(*this, Cond); CondV = EvaluateExprAsBool(Cond); } Builder.CreateCondBr(CondV, TrueBlock, FalseBlock, Weights, Unpredictable); } /// ErrorUnsupported - Print out an error that codegen doesn't support the /// specified stmt yet. void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type) { CGM.ErrorUnsupported(S, Type); } /// emitNonZeroVLAInit - Emit the "zero" initialization of a /// variable-length array whose elements have a non-zero bit-pattern. /// /// \param baseType the inner-most element type of the array /// \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 static void emitNonZeroVLAInit(CodeGenFunction &CGF, QualType baseType, Address dest, Address src, llvm::Value *sizeInChars) { CGBuilderTy &Builder = CGF.Builder; CharUnits baseSize = CGF.getContext().getTypeSizeInChars(baseType); llvm::Value *baseSizeInChars = llvm::ConstantInt::get(CGF.IntPtrTy, baseSize.getQuantity()); Address begin = Builder.CreateElementBitCast(dest, CGF.Int8Ty, "vla.begin"); llvm::Value *end = Builder.CreateInBoundsGEP(begin.getPointer(), 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(begin.getType(), 2, "vla.cur"); cur->addIncoming(begin.getPointer(), originBB); CharUnits curAlign = dest.getAlignment().alignmentOfArrayElement(baseSize); // memcpy the individual element bit-pattern. Builder.CreateMemCpy(Address(cur, curAlign), src, baseSizeInChars, /*volatile*/ false); // Go to the next element. llvm::Value *next = Builder.CreateInBoundsGEP(CGF.Int8Ty, cur, baseSizeInChars, "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(Address DestPtr, QualType Ty) { // Ignore empty classes in C++. if (getLangOpts().CPlusPlus) { if (const RecordType *RT = Ty->getAs()) { if (cast(RT->getDecl())->isEmpty()) return; } } // Cast the dest ptr to the appropriate i8 pointer type. if (DestPtr.getElementType() != Int8Ty) DestPtr = Builder.CreateElementBitCast(DestPtr, Int8Ty); // Get size and alignment info for this aggregate. CharUnits size = getContext().getTypeSizeInChars(Ty); 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))) { auto VlaSize = getVLASize(vlaType); SizeVal = VlaSize.NumElts; CharUnits eltSize = getContext().getTypeSizeInChars(VlaSize.Type); if (!eltSize.isOne()) SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(eltSize)); vla = vlaType; } else { return; } } else { SizeVal = CGM.getSize(size); vla = nullptr; } // 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()); CharUnits NullAlign = DestPtr.getAlignment(); NullVariable->setAlignment(NullAlign.getQuantity()); Address SrcPtr(Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy()), NullAlign); if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal); // Get and call the appropriate llvm.memcpy overload. Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, 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, false); } llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *L) { // Make sure that there is a block for the indirect goto. if (!IndirectBranch) 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(*this, 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, Address &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 = nullptr; if (isa(arrayType)) { numVLAElements = getVLASize(cast(arrayType)).NumElts; // 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); uint64_t countFromCLAs = 1; QualType eltType; llvm::ArrayType *llvmArrayType = dyn_cast(addr.getElementType()); while (llvmArrayType) { assert(isa(arrayType)); assert(cast(arrayType)->getSize().getZExtValue() == llvmArrayType->getNumElements()); gepIndices.push_back(zero); countFromCLAs *= llvmArrayType->getNumElements(); eltType = arrayType->getElementType(); llvmArrayType = dyn_cast(llvmArrayType->getElementType()); arrayType = getContext().getAsArrayType(arrayType->getElementType()); assert((!llvmArrayType || arrayType) && "LLVM and Clang types are out-of-synch"); } if (arrayType) { // From this point onwards, the Clang array type has been emitted // as some other type (probably a packed struct). Compute the array // size, and just emit the 'begin' expression as a bitcast. while (arrayType) { countFromCLAs *= cast(arrayType)->getSize().getZExtValue(); eltType = arrayType->getElementType(); arrayType = getContext().getAsArrayType(eltType); } llvm::Type *baseType = ConvertType(eltType); addr = Builder.CreateElementBitCast(addr, baseType, "array.begin"); } else { // Create the actual GEP. addr = Address(Builder.CreateInBoundsGEP(addr.getPointer(), gepIndices, "array.begin"), addr.getAlignment()); } baseType = eltType; 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; } CodeGenFunction::VlaSizePair CodeGenFunction::getVLASize(QualType type) { const VariableArrayType *vla = getContext().getAsVariableArrayType(type); assert(vla && "type was not a variable array type!"); return getVLASize(vla); } CodeGenFunction::VlaSizePair CodeGenFunction::getVLASize(const VariableArrayType *type) { // The number of elements so far; always size_t. llvm::Value *numElements = nullptr; 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. // FIXME: Teach -fsanitize=undefined to trap this. numElements = Builder.CreateNUWMul(numElements, vlaSize); } } while ((type = getContext().getAsVariableArrayType(elementType))); return { numElements, elementType }; } CodeGenFunction::VlaSizePair CodeGenFunction::getVLAElements1D(QualType type) { const VariableArrayType *vla = getContext().getAsVariableArrayType(type); assert(vla && "type was not a variable array type!"); return getVLAElements1D(vla); } CodeGenFunction::VlaSizePair CodeGenFunction::getVLAElements1D(const VariableArrayType *Vla) { llvm::Value *VlaSize = VLASizeMap[Vla->getSizeExpr()]; assert(VlaSize && "no size for VLA!"); assert(VlaSize->getType() == SizeTy); return { VlaSize, Vla->getElementType() }; } 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. 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) #define DEPENDENT_TYPE(Class, Base) case Type::Class: #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) #include "clang/AST/TypeNodes.def" llvm_unreachable("unexpected dependent 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::Elaborated: case Type::TemplateSpecialization: case Type::ObjCTypeParam: case Type::ObjCObject: case Type::ObjCInterface: case Type::ObjCObjectPointer: llvm_unreachable("type class is never variably-modified!"); case Type::Adjusted: type = cast(ty)->getAdjustedType(); break; case Type::Decayed: type = cast(ty)->getPointeeType(); break; 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) { llvm::Value *Size = EmitScalarExpr(size); // C11 6.7.6.2p5: // If the size is an expression that is not an integer constant // expression [...] each time it is evaluated it shall have a value // greater than zero. if (SanOpts.has(SanitizerKind::VLABound) && size->getType()->isSignedIntegerType()) { SanitizerScope SanScope(this); llvm::Value *Zero = llvm::Constant::getNullValue(Size->getType()); llvm::Constant *StaticArgs[] = { EmitCheckSourceLocation(size->getBeginLoc()), EmitCheckTypeDescriptor(size->getType())}; EmitCheck(std::make_pair(Builder.CreateICmpSGT(Size, Zero), SanitizerKind::VLABound), SanitizerHandler::VLABoundNotPositive, StaticArgs, Size); } // Always zexting here would be wrong if it weren't // undefined behavior to have a negative bound. entry = Builder.CreateIntCast(Size, SizeTy, /*signed*/ false); } } type = vat->getElementType(); break; } case Type::FunctionProto: case Type::FunctionNoProto: type = cast(ty)->getReturnType(); break; case Type::Paren: case Type::TypeOf: case Type::UnaryTransform: case Type::Attributed: case Type::SubstTemplateTypeParm: case Type::PackExpansion: case Type::MacroQualified: // Keep walking after single level desugaring. type = type.getSingleStepDesugaredType(getContext()); break; case Type::Typedef: case Type::Decltype: case Type::Auto: case Type::DeducedTemplateSpecialization: // Stop walking: nothing to do. return; case Type::TypeOfExpr: // Stop walking: emit typeof expression. EmitIgnoredExpr(cast(ty)->getUnderlyingExpr()); return; case Type::Atomic: type = cast(ty)->getValueType(); break; case Type::Pipe: type = cast(ty)->getElementType(); break; } } while (type->isVariablyModifiedType()); } Address CodeGenFunction::EmitVAListRef(const Expr* E) { if (getContext().getBuiltinVaListType()->isArrayType()) return EmitPointerWithAlignment(E); return EmitLValue(E).getAddress(); } Address CodeGenFunction::EmitMSVAListRef(const Expr *E) { return EmitLValue(E).getAddress(); } void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E, const APValue &Init) { assert(Init.hasValue() && "Invalid DeclRefExpr initializer!"); if (CGDebugInfo *Dbg = getDebugInfo()) if (CGM.getCodeGenOpts().getDebugInfo() >= codegenoptions::LimitedDebugInfo) 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(); } void CodeGenFunction::EmitAlignmentAssumption(llvm::Value *PtrValue, QualType Ty, SourceLocation Loc, SourceLocation AssumptionLoc, llvm::Value *Alignment, llvm::Value *OffsetValue) { llvm::Value *TheCheck; llvm::Instruction *Assumption = Builder.CreateAlignmentAssumption( CGM.getDataLayout(), PtrValue, Alignment, OffsetValue, &TheCheck); if (SanOpts.has(SanitizerKind::Alignment)) { EmitAlignmentAssumptionCheck(PtrValue, Ty, Loc, AssumptionLoc, Alignment, OffsetValue, TheCheck, Assumption); } } void CodeGenFunction::EmitAlignmentAssumption(llvm::Value *PtrValue, QualType Ty, SourceLocation Loc, SourceLocation AssumptionLoc, unsigned Alignment, llvm::Value *OffsetValue) { llvm::Value *TheCheck; llvm::Instruction *Assumption = Builder.CreateAlignmentAssumption( CGM.getDataLayout(), PtrValue, Alignment, OffsetValue, &TheCheck); if (SanOpts.has(SanitizerKind::Alignment)) { llvm::Value *AlignmentVal = llvm::ConstantInt::get(IntPtrTy, Alignment); EmitAlignmentAssumptionCheck(PtrValue, Ty, Loc, AssumptionLoc, AlignmentVal, OffsetValue, TheCheck, Assumption); } } void CodeGenFunction::EmitAlignmentAssumption(llvm::Value *PtrValue, const Expr *E, SourceLocation AssumptionLoc, unsigned Alignment, llvm::Value *OffsetValue) { if (auto *CE = dyn_cast(E)) E = CE->getSubExprAsWritten(); QualType Ty = E->getType(); SourceLocation Loc = E->getExprLoc(); EmitAlignmentAssumption(PtrValue, Ty, Loc, AssumptionLoc, Alignment, OffsetValue); } llvm::Value *CodeGenFunction::EmitAnnotationCall(llvm::Function *AnnotationFn, llvm::Value *AnnotatedVal, StringRef AnnotationStr, SourceLocation Location) { llvm::Value *Args[4] = { AnnotatedVal, Builder.CreateBitCast(CGM.EmitAnnotationString(AnnotationStr), Int8PtrTy), Builder.CreateBitCast(CGM.EmitAnnotationUnit(Location), Int8PtrTy), CGM.EmitAnnotationLineNo(Location) }; return Builder.CreateCall(AnnotationFn, Args); } void CodeGenFunction::EmitVarAnnotations(const VarDecl *D, llvm::Value *V) { assert(D->hasAttr() && "no annotate attribute"); // FIXME We create a new bitcast for every annotation because that's what // llvm-gcc was doing. for (const auto *I : D->specific_attrs()) EmitAnnotationCall(CGM.getIntrinsic(llvm::Intrinsic::var_annotation), Builder.CreateBitCast(V, CGM.Int8PtrTy, V->getName()), I->getAnnotation(), D->getLocation()); } Address CodeGenFunction::EmitFieldAnnotations(const FieldDecl *D, Address Addr) { assert(D->hasAttr() && "no annotate attribute"); llvm::Value *V = Addr.getPointer(); llvm::Type *VTy = V->getType(); llvm::Function *F = CGM.getIntrinsic(llvm::Intrinsic::ptr_annotation, CGM.Int8PtrTy); for (const auto *I : D->specific_attrs()) { // FIXME Always emit the cast inst so we can differentiate between // annotation on the first field of a struct and annotation on the struct // itself. if (VTy != CGM.Int8PtrTy) V = Builder.CreateBitCast(V, CGM.Int8PtrTy); V = EmitAnnotationCall(F, V, I->getAnnotation(), D->getLocation()); V = Builder.CreateBitCast(V, VTy); } return Address(V, Addr.getAlignment()); } CodeGenFunction::CGCapturedStmtInfo::~CGCapturedStmtInfo() { } CodeGenFunction::SanitizerScope::SanitizerScope(CodeGenFunction *CGF) : CGF(CGF) { assert(!CGF->IsSanitizerScope); CGF->IsSanitizerScope = true; } CodeGenFunction::SanitizerScope::~SanitizerScope() { CGF->IsSanitizerScope = false; } void CodeGenFunction::InsertHelper(llvm::Instruction *I, const llvm::Twine &Name, llvm::BasicBlock *BB, llvm::BasicBlock::iterator InsertPt) const { LoopStack.InsertHelper(I); if (IsSanitizerScope) CGM.getSanitizerMetadata()->disableSanitizerForInstruction(I); } void CGBuilderInserter::InsertHelper( llvm::Instruction *I, const llvm::Twine &Name, llvm::BasicBlock *BB, llvm::BasicBlock::iterator InsertPt) const { llvm::IRBuilderDefaultInserter::InsertHelper(I, Name, BB, InsertPt); if (CGF) CGF->InsertHelper(I, Name, BB, InsertPt); } static bool hasRequiredFeatures(const SmallVectorImpl &ReqFeatures, CodeGenModule &CGM, const FunctionDecl *FD, std::string &FirstMissing) { // If there aren't any required features listed then go ahead and return. if (ReqFeatures.empty()) return false; // Now build up the set of caller features and verify that all the required // features are there. llvm::StringMap CallerFeatureMap; CGM.getFunctionFeatureMap(CallerFeatureMap, GlobalDecl().getWithDecl(FD)); // If we have at least one of the features in the feature list return // true, otherwise return false. return std::all_of( ReqFeatures.begin(), ReqFeatures.end(), [&](StringRef Feature) { SmallVector OrFeatures; Feature.split(OrFeatures, '|'); return llvm::any_of(OrFeatures, [&](StringRef Feature) { if (!CallerFeatureMap.lookup(Feature)) { FirstMissing = Feature.str(); return false; } return true; }); }); } // Emits an error if we don't have a valid set of target features for the // called function. void CodeGenFunction::checkTargetFeatures(const CallExpr *E, const FunctionDecl *TargetDecl) { return checkTargetFeatures(E->getBeginLoc(), TargetDecl); } // Emits an error if we don't have a valid set of target features for the // called function. void CodeGenFunction::checkTargetFeatures(SourceLocation Loc, const FunctionDecl *TargetDecl) { // Early exit if this is an indirect call. if (!TargetDecl) return; // Get the current enclosing function if it exists. If it doesn't // we can't check the target features anyhow. const FunctionDecl *FD = dyn_cast_or_null(CurFuncDecl); if (!FD) return; // Grab the required features for the call. For a builtin this is listed in // the td file with the default cpu, for an always_inline function this is any // listed cpu and any listed features. unsigned BuiltinID = TargetDecl->getBuiltinID(); std::string MissingFeature; if (BuiltinID) { SmallVector ReqFeatures; const char *FeatureList = CGM.getContext().BuiltinInfo.getRequiredFeatures(BuiltinID); // Return if the builtin doesn't have any required features. if (!FeatureList || StringRef(FeatureList) == "") return; StringRef(FeatureList).split(ReqFeatures, ','); if (!hasRequiredFeatures(ReqFeatures, CGM, FD, MissingFeature)) CGM.getDiags().Report(Loc, diag::err_builtin_needs_feature) << TargetDecl->getDeclName() << CGM.getContext().BuiltinInfo.getRequiredFeatures(BuiltinID); } else if (TargetDecl->hasAttr() || TargetDecl->hasAttr()) { // Get the required features for the callee. const TargetAttr *TD = TargetDecl->getAttr(); TargetAttr::ParsedTargetAttr ParsedAttr = CGM.filterFunctionTargetAttrs(TD); SmallVector ReqFeatures; llvm::StringMap CalleeFeatureMap; CGM.getFunctionFeatureMap(CalleeFeatureMap, TargetDecl); for (const auto &F : ParsedAttr.Features) { if (F[0] == '+' && CalleeFeatureMap.lookup(F.substr(1))) ReqFeatures.push_back(StringRef(F).substr(1)); } for (const auto &F : CalleeFeatureMap) { // Only positive features are "required". if (F.getValue()) ReqFeatures.push_back(F.getKey()); } if (!hasRequiredFeatures(ReqFeatures, CGM, FD, MissingFeature)) CGM.getDiags().Report(Loc, diag::err_function_needs_feature) << FD->getDeclName() << TargetDecl->getDeclName() << MissingFeature; } } void CodeGenFunction::EmitSanitizerStatReport(llvm::SanitizerStatKind SSK) { if (!CGM.getCodeGenOpts().SanitizeStats) return; llvm::IRBuilder<> IRB(Builder.GetInsertBlock(), Builder.GetInsertPoint()); IRB.SetCurrentDebugLocation(Builder.getCurrentDebugLocation()); CGM.getSanStats().create(IRB, SSK); } llvm::Value * CodeGenFunction::FormResolverCondition(const MultiVersionResolverOption &RO) { llvm::Value *Condition = nullptr; if (!RO.Conditions.Architecture.empty()) Condition = EmitX86CpuIs(RO.Conditions.Architecture); if (!RO.Conditions.Features.empty()) { llvm::Value *FeatureCond = EmitX86CpuSupports(RO.Conditions.Features); Condition = Condition ? Builder.CreateAnd(Condition, FeatureCond) : FeatureCond; } return Condition; } static void CreateMultiVersionResolverReturn(CodeGenModule &CGM, llvm::Function *Resolver, CGBuilderTy &Builder, llvm::Function *FuncToReturn, bool SupportsIFunc) { if (SupportsIFunc) { Builder.CreateRet(FuncToReturn); return; } llvm::SmallVector Args; llvm::for_each(Resolver->args(), [&](llvm::Argument &Arg) { Args.push_back(&Arg); }); llvm::CallInst *Result = Builder.CreateCall(FuncToReturn, Args); Result->setTailCallKind(llvm::CallInst::TCK_MustTail); if (Resolver->getReturnType()->isVoidTy()) Builder.CreateRetVoid(); else Builder.CreateRet(Result); } void CodeGenFunction::EmitMultiVersionResolver( llvm::Function *Resolver, ArrayRef Options) { assert((getContext().getTargetInfo().getTriple().getArch() == llvm::Triple::x86 || getContext().getTargetInfo().getTriple().getArch() == llvm::Triple::x86_64) && "Only implemented for x86 targets"); bool SupportsIFunc = getContext().getTargetInfo().supportsIFunc(); // Main function's basic block. llvm::BasicBlock *CurBlock = createBasicBlock("resolver_entry", Resolver); Builder.SetInsertPoint(CurBlock); EmitX86CpuInit(); for (const MultiVersionResolverOption &RO : Options) { Builder.SetInsertPoint(CurBlock); llvm::Value *Condition = FormResolverCondition(RO); // The 'default' or 'generic' case. if (!Condition) { assert(&RO == Options.end() - 1 && "Default or Generic case must be last"); CreateMultiVersionResolverReturn(CGM, Resolver, Builder, RO.Function, SupportsIFunc); return; } llvm::BasicBlock *RetBlock = createBasicBlock("resolver_return", Resolver); CGBuilderTy RetBuilder(*this, RetBlock); CreateMultiVersionResolverReturn(CGM, Resolver, RetBuilder, RO.Function, SupportsIFunc); CurBlock = createBasicBlock("resolver_else", Resolver); Builder.CreateCondBr(Condition, RetBlock, CurBlock); } // If no generic/default, emit an unreachable. Builder.SetInsertPoint(CurBlock); llvm::CallInst *TrapCall = EmitTrapCall(llvm::Intrinsic::trap); TrapCall->setDoesNotReturn(); TrapCall->setDoesNotThrow(); Builder.CreateUnreachable(); Builder.ClearInsertionPoint(); } // Loc - where the diagnostic will point, where in the source code this // alignment has failed. // SecondaryLoc - if present (will be present if sufficiently different from // Loc), the diagnostic will additionally point a "Note:" to this location. // It should be the location where the __attribute__((assume_aligned)) // was written e.g. void CodeGenFunction::EmitAlignmentAssumptionCheck( llvm::Value *Ptr, QualType Ty, SourceLocation Loc, SourceLocation SecondaryLoc, llvm::Value *Alignment, llvm::Value *OffsetValue, llvm::Value *TheCheck, llvm::Instruction *Assumption) { assert(Assumption && isa(Assumption) && cast(Assumption)->getCalledValue() == llvm::Intrinsic::getDeclaration( Builder.GetInsertBlock()->getParent()->getParent(), llvm::Intrinsic::assume) && "Assumption should be a call to llvm.assume()."); assert(&(Builder.GetInsertBlock()->back()) == Assumption && "Assumption should be the last instruction of the basic block, " "since the basic block is still being generated."); if (!SanOpts.has(SanitizerKind::Alignment)) return; // Don't check pointers to volatile data. The behavior here is implementation- // defined. if (Ty->getPointeeType().isVolatileQualified()) return; // We need to temorairly remove the assumption so we can insert the // sanitizer check before it, else the check will be dropped by optimizations. Assumption->removeFromParent(); { SanitizerScope SanScope(this); if (!OffsetValue) OffsetValue = Builder.getInt1(0); // no offset. llvm::Constant *StaticData[] = {EmitCheckSourceLocation(Loc), EmitCheckSourceLocation(SecondaryLoc), EmitCheckTypeDescriptor(Ty)}; llvm::Value *DynamicData[] = {EmitCheckValue(Ptr), EmitCheckValue(Alignment), EmitCheckValue(OffsetValue)}; EmitCheck({std::make_pair(TheCheck, SanitizerKind::Alignment)}, SanitizerHandler::AlignmentAssumption, StaticData, DynamicData); } // We are now in the (new, empty) "cont" basic block. // Reintroduce the assumption. Builder.Insert(Assumption); // FIXME: Assumption still has it's original basic block as it's Parent. } llvm::DebugLoc CodeGenFunction::SourceLocToDebugLoc(SourceLocation Location) { if (CGDebugInfo *DI = getDebugInfo()) return DI->SourceLocToDebugLoc(Location); return llvm::DebugLoc(); }