forked from OSchip/llvm-project
417 lines
15 KiB
C++
417 lines
15 KiB
C++
//===--- CGDeclCXX.cpp - Emit LLVM Code for C++ declarations --------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This contains code dealing with code generation of C++ declarations
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//
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//===----------------------------------------------------------------------===//
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#include "CodeGenFunction.h"
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#include "CGObjCRuntime.h"
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#include "CGCXXABI.h"
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#include "clang/Frontend/CodeGenOptions.h"
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#include "llvm/Intrinsics.h"
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using namespace clang;
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using namespace CodeGen;
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static void EmitDeclInit(CodeGenFunction &CGF, const VarDecl &D,
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llvm::Constant *DeclPtr) {
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assert(D.hasGlobalStorage() && "VarDecl must have global storage!");
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assert(!D.getType()->isReferenceType() &&
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"Should not call EmitDeclInit on a reference!");
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ASTContext &Context = CGF.getContext();
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CharUnits alignment = Context.getDeclAlign(&D);
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QualType type = D.getType();
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LValue lv = CGF.MakeAddrLValue(DeclPtr, type, alignment);
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const Expr *Init = D.getInit();
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if (!CGF.hasAggregateLLVMType(type)) {
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CodeGenModule &CGM = CGF.CGM;
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if (lv.isObjCStrong())
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CGM.getObjCRuntime().EmitObjCGlobalAssign(CGF, CGF.EmitScalarExpr(Init),
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DeclPtr, D.isThreadSpecified());
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else if (lv.isObjCWeak())
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CGM.getObjCRuntime().EmitObjCWeakAssign(CGF, CGF.EmitScalarExpr(Init),
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DeclPtr);
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else
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CGF.EmitScalarInit(Init, &D, lv, false);
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} else if (type->isAnyComplexType()) {
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CGF.EmitComplexExprIntoAddr(Init, DeclPtr, lv.isVolatile());
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} else {
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CGF.EmitAggExpr(Init, AggValueSlot::forLValue(lv,AggValueSlot::IsDestructed,
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AggValueSlot::DoesNotNeedGCBarriers,
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AggValueSlot::IsNotAliased));
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}
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}
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/// Emit code to cause the destruction of the given variable with
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/// static storage duration.
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static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D,
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llvm::Constant *addr) {
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CodeGenModule &CGM = CGF.CGM;
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// FIXME: __attribute__((cleanup)) ?
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QualType type = D.getType();
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QualType::DestructionKind dtorKind = type.isDestructedType();
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switch (dtorKind) {
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case QualType::DK_none:
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return;
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case QualType::DK_cxx_destructor:
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break;
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case QualType::DK_objc_strong_lifetime:
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case QualType::DK_objc_weak_lifetime:
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// We don't care about releasing objects during process teardown.
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return;
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}
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llvm::Constant *function;
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llvm::Constant *argument;
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// Special-case non-array C++ destructors, where there's a function
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// with the right signature that we can just call.
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const CXXRecordDecl *record = 0;
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if (dtorKind == QualType::DK_cxx_destructor &&
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(record = type->getAsCXXRecordDecl())) {
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assert(!record->hasTrivialDestructor());
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CXXDestructorDecl *dtor = record->getDestructor();
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function = CGM.GetAddrOfCXXDestructor(dtor, Dtor_Complete);
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argument = addr;
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// Otherwise, the standard logic requires a helper function.
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} else {
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function = CodeGenFunction(CGM).generateDestroyHelper(addr, type,
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CGF.getDestroyer(dtorKind),
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CGF.needsEHCleanup(dtorKind));
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argument = llvm::Constant::getNullValue(CGF.Int8PtrTy);
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}
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CGM.getCXXABI().registerGlobalDtor(CGF, function, argument);
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}
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/// Emit code to cause the variable at the given address to be considered as
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/// constant from this point onwards.
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static void EmitDeclInvariant(CodeGenFunction &CGF, const VarDecl &D,
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llvm::Constant *Addr) {
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// Don't emit the intrinsic if we're not optimizing.
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if (!CGF.CGM.getCodeGenOpts().OptimizationLevel)
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return;
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// Grab the llvm.invariant.start intrinsic.
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llvm::Intrinsic::ID InvStartID = llvm::Intrinsic::invariant_start;
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llvm::Constant *InvariantStart = CGF.CGM.getIntrinsic(InvStartID);
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// Emit a call with the size in bytes of the object.
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CharUnits WidthChars = CGF.getContext().getTypeSizeInChars(D.getType());
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uint64_t Width = WidthChars.getQuantity();
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llvm::Value *Args[2] = { llvm::ConstantInt::getSigned(CGF.Int64Ty, Width),
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llvm::ConstantExpr::getBitCast(Addr, CGF.Int8PtrTy)};
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CGF.Builder.CreateCall(InvariantStart, Args);
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}
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void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D,
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llvm::Constant *DeclPtr,
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bool PerformInit) {
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const Expr *Init = D.getInit();
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QualType T = D.getType();
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if (!T->isReferenceType()) {
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if (PerformInit)
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EmitDeclInit(*this, D, DeclPtr);
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if (CGM.isTypeConstant(D.getType(), true))
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EmitDeclInvariant(*this, D, DeclPtr);
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else
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EmitDeclDestroy(*this, D, DeclPtr);
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return;
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}
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assert(PerformInit && "cannot have constant initializer which needs "
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"destruction for reference");
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unsigned Alignment = getContext().getDeclAlign(&D).getQuantity();
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RValue RV = EmitReferenceBindingToExpr(Init, &D);
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EmitStoreOfScalar(RV.getScalarVal(), DeclPtr, false, Alignment, T);
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}
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static llvm::Function *
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CreateGlobalInitOrDestructFunction(CodeGenModule &CGM,
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llvm::FunctionType *ty,
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const Twine &name);
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/// Create a stub function, suitable for being passed to atexit,
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/// which passes the given address to the given destructor function.
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static llvm::Constant *createAtExitStub(CodeGenModule &CGM,
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llvm::Constant *dtor,
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llvm::Constant *addr) {
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// Get the destructor function type, void(*)(void).
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llvm::FunctionType *ty = llvm::FunctionType::get(CGM.VoidTy, false);
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llvm::Function *fn =
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CreateGlobalInitOrDestructFunction(CGM, ty,
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Twine("__dtor_", addr->getName()));
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CodeGenFunction CGF(CGM);
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CGF.StartFunction(GlobalDecl(), CGM.getContext().VoidTy, fn,
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CGM.getTypes().arrangeNullaryFunction(),
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FunctionArgList(), SourceLocation());
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llvm::CallInst *call = CGF.Builder.CreateCall(dtor, addr);
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// Make sure the call and the callee agree on calling convention.
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if (llvm::Function *dtorFn =
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dyn_cast<llvm::Function>(dtor->stripPointerCasts()))
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call->setCallingConv(dtorFn->getCallingConv());
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CGF.FinishFunction();
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return fn;
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}
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/// Register a global destructor using the C atexit runtime function.
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void CodeGenFunction::registerGlobalDtorWithAtExit(llvm::Constant *dtor,
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llvm::Constant *addr) {
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// Create a function which calls the destructor.
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llvm::Constant *dtorStub = createAtExitStub(CGM, dtor, addr);
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// extern "C" int atexit(void (*f)(void));
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llvm::FunctionType *atexitTy =
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llvm::FunctionType::get(IntTy, dtorStub->getType(), false);
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llvm::Constant *atexit =
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CGM.CreateRuntimeFunction(atexitTy, "atexit");
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if (llvm::Function *atexitFn = dyn_cast<llvm::Function>(atexit))
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atexitFn->setDoesNotThrow();
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Builder.CreateCall(atexit, dtorStub)->setDoesNotThrow();
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}
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void CodeGenFunction::EmitCXXGuardedInit(const VarDecl &D,
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llvm::GlobalVariable *DeclPtr,
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bool PerformInit) {
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// If we've been asked to forbid guard variables, emit an error now.
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// This diagnostic is hard-coded for Darwin's use case; we can find
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// better phrasing if someone else needs it.
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if (CGM.getCodeGenOpts().ForbidGuardVariables)
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CGM.Error(D.getLocation(),
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"this initialization requires a guard variable, which "
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"the kernel does not support");
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CGM.getCXXABI().EmitGuardedInit(*this, D, DeclPtr, PerformInit);
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}
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static llvm::Function *
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CreateGlobalInitOrDestructFunction(CodeGenModule &CGM,
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llvm::FunctionType *FTy,
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const Twine &Name) {
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llvm::Function *Fn =
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llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage,
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Name, &CGM.getModule());
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if (!CGM.getContext().getLangOpts().AppleKext) {
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// Set the section if needed.
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if (const char *Section =
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CGM.getContext().getTargetInfo().getStaticInitSectionSpecifier())
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Fn->setSection(Section);
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}
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if (!CGM.getLangOpts().Exceptions)
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Fn->setDoesNotThrow();
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if (CGM.getLangOpts().AddressSanitizer)
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Fn->addFnAttr(llvm::Attributes::AddressSafety);
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return Fn;
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}
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void
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CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
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llvm::GlobalVariable *Addr,
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bool PerformInit) {
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llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
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// Create a variable initialization function.
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llvm::Function *Fn =
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CreateGlobalInitOrDestructFunction(*this, FTy, "__cxx_global_var_init");
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CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr,
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PerformInit);
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if (D->hasAttr<InitPriorityAttr>()) {
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unsigned int order = D->getAttr<InitPriorityAttr>()->getPriority();
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OrderGlobalInits Key(order, PrioritizedCXXGlobalInits.size());
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PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
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DelayedCXXInitPosition.erase(D);
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}
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else {
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llvm::DenseMap<const Decl *, unsigned>::iterator I =
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DelayedCXXInitPosition.find(D);
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if (I == DelayedCXXInitPosition.end()) {
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CXXGlobalInits.push_back(Fn);
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} else {
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assert(CXXGlobalInits[I->second] == 0);
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CXXGlobalInits[I->second] = Fn;
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DelayedCXXInitPosition.erase(I);
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}
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}
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}
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void
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CodeGenModule::EmitCXXGlobalInitFunc() {
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while (!CXXGlobalInits.empty() && !CXXGlobalInits.back())
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CXXGlobalInits.pop_back();
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if (CXXGlobalInits.empty() && PrioritizedCXXGlobalInits.empty())
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return;
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llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
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// Create our global initialization function.
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llvm::Function *Fn =
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CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__I_a");
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if (!PrioritizedCXXGlobalInits.empty()) {
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SmallVector<llvm::Constant*, 8> LocalCXXGlobalInits;
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llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(),
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PrioritizedCXXGlobalInits.end());
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for (unsigned i = 0; i < PrioritizedCXXGlobalInits.size(); i++) {
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llvm::Function *Fn = PrioritizedCXXGlobalInits[i].second;
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LocalCXXGlobalInits.push_back(Fn);
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}
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LocalCXXGlobalInits.append(CXXGlobalInits.begin(), CXXGlobalInits.end());
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CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn,
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&LocalCXXGlobalInits[0],
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LocalCXXGlobalInits.size());
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}
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else
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CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn,
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&CXXGlobalInits[0],
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CXXGlobalInits.size());
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AddGlobalCtor(Fn);
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CXXGlobalInits.clear();
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PrioritizedCXXGlobalInits.clear();
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}
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void CodeGenModule::EmitCXXGlobalDtorFunc() {
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if (CXXGlobalDtors.empty())
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return;
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llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
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// Create our global destructor function.
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llvm::Function *Fn =
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CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__D_a");
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CodeGenFunction(*this).GenerateCXXGlobalDtorsFunc(Fn, CXXGlobalDtors);
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AddGlobalDtor(Fn);
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}
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/// Emit the code necessary to initialize the given global variable.
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void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn,
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const VarDecl *D,
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llvm::GlobalVariable *Addr,
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bool PerformInit) {
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if (CGM.getModuleDebugInfo() && !D->hasAttr<NoDebugAttr>())
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DebugInfo = CGM.getModuleDebugInfo();
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StartFunction(GlobalDecl(D), getContext().VoidTy, Fn,
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getTypes().arrangeNullaryFunction(),
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FunctionArgList(), D->getInit()->getExprLoc());
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// Use guarded initialization if the global variable is weak. This
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// occurs for, e.g., instantiated static data members and
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// definitions explicitly marked weak.
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if (Addr->getLinkage() == llvm::GlobalValue::WeakODRLinkage ||
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Addr->getLinkage() == llvm::GlobalValue::WeakAnyLinkage) {
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EmitCXXGuardedInit(*D, Addr, PerformInit);
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} else {
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EmitCXXGlobalVarDeclInit(*D, Addr, PerformInit);
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}
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FinishFunction();
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}
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void CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,
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llvm::Constant **Decls,
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unsigned NumDecls) {
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StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
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getTypes().arrangeNullaryFunction(),
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FunctionArgList(), SourceLocation());
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RunCleanupsScope Scope(*this);
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// When building in Objective-C++ ARC mode, create an autorelease pool
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// around the global initializers.
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if (getLangOpts().ObjCAutoRefCount && getLangOpts().CPlusPlus) {
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llvm::Value *token = EmitObjCAutoreleasePoolPush();
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EmitObjCAutoreleasePoolCleanup(token);
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}
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for (unsigned i = 0; i != NumDecls; ++i)
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if (Decls[i])
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Builder.CreateCall(Decls[i]);
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Scope.ForceCleanup();
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FinishFunction();
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}
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void CodeGenFunction::GenerateCXXGlobalDtorsFunc(llvm::Function *Fn,
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const std::vector<std::pair<llvm::WeakVH, llvm::Constant*> >
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&DtorsAndObjects) {
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StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
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getTypes().arrangeNullaryFunction(),
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FunctionArgList(), SourceLocation());
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// Emit the dtors, in reverse order from construction.
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for (unsigned i = 0, e = DtorsAndObjects.size(); i != e; ++i) {
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llvm::Value *Callee = DtorsAndObjects[e - i - 1].first;
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llvm::CallInst *CI = Builder.CreateCall(Callee,
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DtorsAndObjects[e - i - 1].second);
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// Make sure the call and the callee agree on calling convention.
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if (llvm::Function *F = dyn_cast<llvm::Function>(Callee))
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CI->setCallingConv(F->getCallingConv());
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}
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FinishFunction();
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}
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/// generateDestroyHelper - Generates a helper function which, when
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/// invoked, destroys the given object.
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llvm::Function *
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CodeGenFunction::generateDestroyHelper(llvm::Constant *addr,
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QualType type,
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Destroyer *destroyer,
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bool useEHCleanupForArray) {
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FunctionArgList args;
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ImplicitParamDecl dst(0, SourceLocation(), 0, getContext().VoidPtrTy);
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args.push_back(&dst);
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const CGFunctionInfo &FI =
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CGM.getTypes().arrangeFunctionDeclaration(getContext().VoidTy, args,
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FunctionType::ExtInfo(),
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/*variadic*/ false);
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llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI);
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llvm::Function *fn =
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CreateGlobalInitOrDestructFunction(CGM, FTy, "__cxx_global_array_dtor");
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StartFunction(GlobalDecl(), getContext().VoidTy, fn, FI, args,
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SourceLocation());
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emitDestroy(addr, type, destroyer, useEHCleanupForArray);
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FinishFunction();
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return fn;
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}
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