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llvm-project/clang/lib/CodeGen/CGDecl.cpp

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//===--- CGDecl.cpp - Emit LLVM Code for declarations ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This contains code to emit Decl nodes as LLVM code.
//
//===----------------------------------------------------------------------===//
#include "CGDebugInfo.h"
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "CGOpenCLRuntime.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclObjC.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Frontend/CodeGenOptions.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Intrinsics.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Type.h"
using namespace clang;
using namespace CodeGen;
void CodeGenFunction::EmitDecl(const Decl &D) {
switch (D.getKind()) {
case Decl::TranslationUnit:
case Decl::Namespace:
case Decl::UnresolvedUsingTypename:
case Decl::ClassTemplateSpecialization:
case Decl::ClassTemplatePartialSpecialization:
case Decl::TemplateTypeParm:
case Decl::UnresolvedUsingValue:
case Decl::NonTypeTemplateParm:
case Decl::CXXMethod:
case Decl::CXXConstructor:
case Decl::CXXDestructor:
case Decl::CXXConversion:
case Decl::Field:
case Decl::IndirectField:
case Decl::ObjCIvar:
case Decl::ObjCAtDefsField:
case Decl::ParmVar:
case Decl::ImplicitParam:
case Decl::ClassTemplate:
case Decl::FunctionTemplate:
case Decl::TypeAliasTemplate:
case Decl::TemplateTemplateParm:
case Decl::ObjCMethod:
case Decl::ObjCCategory:
case Decl::ObjCProtocol:
case Decl::ObjCInterface:
case Decl::ObjCCategoryImpl:
case Decl::ObjCImplementation:
case Decl::ObjCProperty:
case Decl::ObjCCompatibleAlias:
case Decl::AccessSpec:
case Decl::LinkageSpec:
case Decl::ObjCPropertyImpl:
case Decl::ObjCClass:
case Decl::ObjCForwardProtocol:
case Decl::FileScopeAsm:
case Decl::Friend:
case Decl::FriendTemplate:
case Decl::Block:
case Decl::ClassScopeFunctionSpecialization:
llvm_unreachable("Declaration should not be in declstmts!");
case Decl::Function: // void X();
case Decl::Record: // struct/union/class X;
case Decl::Enum: // enum X;
case Decl::EnumConstant: // enum ? { X = ? }
case Decl::CXXRecord: // struct/union/class X; [C++]
case Decl::Using: // using X; [C++]
case Decl::UsingShadow:
case Decl::UsingDirective: // using namespace X; [C++]
case Decl::NamespaceAlias:
case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
case Decl::Label: // __label__ x;
// None of these decls require codegen support.
return;
case Decl::Var: {
const VarDecl &VD = cast<VarDecl>(D);
assert(VD.isLocalVarDecl() &&
"Should not see file-scope variables inside a function!");
return EmitVarDecl(VD);
}
case Decl::Typedef: // typedef int X;
case Decl::TypeAlias: { // using X = int; [C++0x]
const TypedefNameDecl &TD = cast<TypedefNameDecl>(D);
QualType Ty = TD.getUnderlyingType();
if (Ty->isVariablyModifiedType())
EmitVariablyModifiedType(Ty);
}
}
}
/// EmitVarDecl - This method handles emission of any variable declaration
/// inside a function, including static vars etc.
void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
switch (D.getStorageClass()) {
case SC_None:
case SC_Auto:
case SC_Register:
return EmitAutoVarDecl(D);
case SC_Static: {
llvm::GlobalValue::LinkageTypes Linkage =
llvm::GlobalValue::InternalLinkage;
// If the function definition has some sort of weak linkage, its
// static variables should also be weak so that they get properly
// uniqued. We can't do this in C, though, because there's no
// standard way to agree on which variables are the same (i.e.
// there's no mangling).
if (getContext().getLangOptions().CPlusPlus)
if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage()))
Linkage = CurFn->getLinkage();
return EmitStaticVarDecl(D, Linkage);
}
case SC_Extern:
case SC_PrivateExtern:
// Don't emit it now, allow it to be emitted lazily on its first use.
return;
case SC_OpenCLWorkGroupLocal:
return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D);
}
llvm_unreachable("Unknown storage class");
}
static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D,
const char *Separator) {
CodeGenModule &CGM = CGF.CGM;
if (CGF.getContext().getLangOptions().CPlusPlus) {
StringRef Name = CGM.getMangledName(&D);
return Name.str();
}
std::string ContextName;
if (!CGF.CurFuncDecl) {
// Better be in a block declared in global scope.
const NamedDecl *ND = cast<NamedDecl>(&D);
const DeclContext *DC = ND->getDeclContext();
if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) {
MangleBuffer Name;
CGM.getBlockMangledName(GlobalDecl(), Name, BD);
ContextName = Name.getString();
}
else
llvm_unreachable("Unknown context for block static var decl");
} else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) {
StringRef Name = CGM.getMangledName(FD);
ContextName = Name.str();
} else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl))
ContextName = CGF.CurFn->getName();
else
llvm_unreachable("Unknown context for static var decl");
return ContextName + Separator + D.getNameAsString();
}
llvm::GlobalVariable *
CodeGenFunction::CreateStaticVarDecl(const VarDecl &D,
const char *Separator,
llvm::GlobalValue::LinkageTypes Linkage) {
QualType Ty = D.getType();
assert(Ty->isConstantSizeType() && "VLAs can't be static");
std::string Name = GetStaticDeclName(*this, D, Separator);
llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
llvm::GlobalVariable *GV =
new llvm::GlobalVariable(CGM.getModule(), LTy,
Ty.isConstant(getContext()), Linkage,
CGM.EmitNullConstant(D.getType()), Name, 0,
D.isThreadSpecified(),
CGM.getContext().getTargetAddressSpace(Ty));
GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
if (Linkage != llvm::GlobalValue::InternalLinkage)
GV->setVisibility(CurFn->getVisibility());
return GV;
}
/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the
/// global variable that has already been created for it. If the initializer
/// has a different type than GV does, this may free GV and return a different
/// one. Otherwise it just returns GV.
llvm::GlobalVariable *
CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
llvm::GlobalVariable *GV) {
llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(), D.getType(), this);
// If constant emission failed, then this should be a C++ static
// initializer.
if (!Init) {
if (!getContext().getLangOptions().CPlusPlus)
CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
else if (Builder.GetInsertBlock()) {
// Since we have a static initializer, this global variable can't
// be constant.
GV->setConstant(false);
EmitCXXGuardedInit(D, GV);
}
return GV;
}
// The initializer may differ in type from the global. Rewrite
// the global to match the initializer. (We have to do this
// because some types, like unions, can't be completely represented
// in the LLVM type system.)
if (GV->getType()->getElementType() != Init->getType()) {
llvm::GlobalVariable *OldGV = GV;
GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
OldGV->isConstant(),
OldGV->getLinkage(), Init, "",
/*InsertBefore*/ OldGV,
D.isThreadSpecified(),
CGM.getContext().getTargetAddressSpace(D.getType()));
GV->setVisibility(OldGV->getVisibility());
// Steal the name of the old global
GV->takeName(OldGV);
// Replace all uses of the old global with the new global
llvm::Constant *NewPtrForOldDecl =
llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
OldGV->replaceAllUsesWith(NewPtrForOldDecl);
// Erase the old global, since it is no longer used.
OldGV->eraseFromParent();
}
GV->setInitializer(Init);
return GV;
}
void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
llvm::GlobalValue::LinkageTypes Linkage) {
llvm::Value *&DMEntry = LocalDeclMap[&D];
assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
llvm::GlobalVariable *GV = CreateStaticVarDecl(D, ".", Linkage);
// Store into LocalDeclMap before generating initializer to handle
// circular references.
DMEntry = GV;
// We can't have a VLA here, but we can have a pointer to a VLA,
// even though that doesn't really make any sense.
// Make sure to evaluate VLA bounds now so that we have them for later.
if (D.getType()->isVariablyModifiedType())
EmitVariablyModifiedType(D.getType());
// Local static block variables must be treated as globals as they may be
// referenced in their RHS initializer block-literal expresion.
CGM.setStaticLocalDeclAddress(&D, GV);
// If this value has an initializer, emit it.
if (D.getInit())
GV = AddInitializerToStaticVarDecl(D, GV);
GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
if (D.hasAttr<AnnotateAttr>())
CGM.AddGlobalAnnotations(&D, GV);
if (const SectionAttr *SA = D.getAttr<SectionAttr>())
GV->setSection(SA->getName());
if (D.hasAttr<UsedAttr>())
CGM.AddUsedGlobal(GV);
// We may have to cast the constant because of the initializer
// mismatch above.
//
// FIXME: It is really dangerous to store this in the map; if anyone
// RAUW's the GV uses of this constant will be invalid.
llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(D.getType());
llvm::Type *LPtrTy =
LTy->getPointerTo(CGM.getContext().getTargetAddressSpace(D.getType()));
DMEntry = llvm::ConstantExpr::getBitCast(GV, LPtrTy);
// Emit global variable debug descriptor for static vars.
CGDebugInfo *DI = getDebugInfo();
if (DI) {
DI->setLocation(D.getLocation());
DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(GV), &D);
}
}
namespace {
struct DestroyObject : EHScopeStack::Cleanup {
DestroyObject(llvm::Value *addr, QualType type,
CodeGenFunction::Destroyer *destroyer,
bool useEHCleanupForArray)
: addr(addr), type(type), destroyer(*destroyer),
useEHCleanupForArray(useEHCleanupForArray) {}
llvm::Value *addr;
QualType type;
CodeGenFunction::Destroyer &destroyer;
bool useEHCleanupForArray;
void Emit(CodeGenFunction &CGF, Flags flags) {
// Don't use an EH cleanup recursively from an EH cleanup.
bool useEHCleanupForArray =
flags.isForNormalCleanup() && this->useEHCleanupForArray;
CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray);
}
};
struct DestroyNRVOVariable : EHScopeStack::Cleanup {
DestroyNRVOVariable(llvm::Value *addr,
const CXXDestructorDecl *Dtor,
llvm::Value *NRVOFlag)
: Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {}
const CXXDestructorDecl *Dtor;
llvm::Value *NRVOFlag;
llvm::Value *Loc;
void Emit(CodeGenFunction &CGF, Flags flags) {
// Along the exceptions path we always execute the dtor.
bool NRVO = flags.isForNormalCleanup() && NRVOFlag;
llvm::BasicBlock *SkipDtorBB = 0;
if (NRVO) {
// If we exited via NRVO, we skip the destructor call.
llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val");
CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
CGF.EmitBlock(RunDtorBB);
}
CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
/*ForVirtualBase=*/false, Loc);
if (NRVO) CGF.EmitBlock(SkipDtorBB);
}
};
struct CallStackRestore : EHScopeStack::Cleanup {
llvm::Value *Stack;
CallStackRestore(llvm::Value *Stack) : Stack(Stack) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
llvm::Value *V = CGF.Builder.CreateLoad(Stack);
llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
CGF.Builder.CreateCall(F, V);
}
};
struct ExtendGCLifetime : EHScopeStack::Cleanup {
const VarDecl &Var;
ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
// Compute the address of the local variable, in case it's a
// byref or something.
DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue,
SourceLocation());
llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE));
CGF.EmitExtendGCLifetime(value);
}
};
struct CallCleanupFunction : EHScopeStack::Cleanup {
llvm::Constant *CleanupFn;
const CGFunctionInfo &FnInfo;
const VarDecl &Var;
CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
const VarDecl *Var)
: CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue,
SourceLocation());
// Compute the address of the local variable, in case it's a byref
// or something.
llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress();
// In some cases, the type of the function argument will be different from
// the type of the pointer. An example of this is
// void f(void* arg);
// __attribute__((cleanup(f))) void *g;
//
// To fix this we insert a bitcast here.
QualType ArgTy = FnInfo.arg_begin()->type;
llvm::Value *Arg =
CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
CallArgList Args;
Args.add(RValue::get(Arg),
CGF.getContext().getPointerType(Var.getType()));
CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
}
};
}
/// EmitAutoVarWithLifetime - Does the setup required for an automatic
/// variable with lifetime.
static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
llvm::Value *addr,
Qualifiers::ObjCLifetime lifetime) {
switch (lifetime) {
case Qualifiers::OCL_None:
llvm_unreachable("present but none");
case Qualifiers::OCL_ExplicitNone:
// nothing to do
break;
case Qualifiers::OCL_Strong: {
CodeGenFunction::Destroyer &destroyer =
(var.hasAttr<ObjCPreciseLifetimeAttr>()
? CodeGenFunction::destroyARCStrongPrecise
: CodeGenFunction::destroyARCStrongImprecise);
CleanupKind cleanupKind = CGF.getARCCleanupKind();
CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
cleanupKind & EHCleanup);
break;
}
case Qualifiers::OCL_Autoreleasing:
// nothing to do
break;
case Qualifiers::OCL_Weak:
// __weak objects always get EH cleanups; otherwise, exceptions
// could cause really nasty crashes instead of mere leaks.
CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
CodeGenFunction::destroyARCWeak,
/*useEHCleanup*/ true);
break;
}
}
static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
if (const Expr *e = dyn_cast<Expr>(s)) {
// Skip the most common kinds of expressions that make
// hierarchy-walking expensive.
s = e = e->IgnoreParenCasts();
if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
return (ref->getDecl() == &var);
}
for (Stmt::const_child_range children = s->children(); children; ++children)
// children might be null; as in missing decl or conditional of an if-stmt.
if ((*children) && isAccessedBy(var, *children))
return true;
return false;
}
static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
if (!decl) return false;
if (!isa<VarDecl>(decl)) return false;
const VarDecl *var = cast<VarDecl>(decl);
return isAccessedBy(*var, e);
}
static void drillIntoBlockVariable(CodeGenFunction &CGF,
LValue &lvalue,
const VarDecl *var) {
lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var));
}
void CodeGenFunction::EmitScalarInit(const Expr *init,
const ValueDecl *D,
LValue lvalue,
bool capturedByInit) {
Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
if (!lifetime) {
llvm::Value *value = EmitScalarExpr(init);
if (capturedByInit)
drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
EmitStoreThroughLValue(RValue::get(value), lvalue);
return;
}
// If we're emitting a value with lifetime, we have to do the
// initialization *before* we leave the cleanup scopes.
if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) {
enterFullExpression(ewc);
init = ewc->getSubExpr();
}
CodeGenFunction::RunCleanupsScope Scope(*this);
// We have to maintain the illusion that the variable is
// zero-initialized. If the variable might be accessed in its
// initializer, zero-initialize before running the initializer, then
// actually perform the initialization with an assign.
bool accessedByInit = false;
if (lifetime != Qualifiers::OCL_ExplicitNone)
accessedByInit = (capturedByInit || isAccessedBy(D, init));
if (accessedByInit) {
LValue tempLV = lvalue;
// Drill down to the __block object if necessary.
if (capturedByInit) {
// We can use a simple GEP for this because it can't have been
// moved yet.
tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(),
getByRefValueLLVMField(cast<VarDecl>(D))));
}
llvm::PointerType *ty
= cast<llvm::PointerType>(tempLV.getAddress()->getType());
ty = cast<llvm::PointerType>(ty->getElementType());
llvm::Value *zero = llvm::ConstantPointerNull::get(ty);
// If __weak, we want to use a barrier under certain conditions.
if (lifetime == Qualifiers::OCL_Weak)
EmitARCInitWeak(tempLV.getAddress(), zero);
// Otherwise just do a simple store.
else
EmitStoreOfScalar(zero, tempLV);
}
// Emit the initializer.
llvm::Value *value = 0;
switch (lifetime) {
case Qualifiers::OCL_None:
llvm_unreachable("present but none");
case Qualifiers::OCL_ExplicitNone:
// nothing to do
value = EmitScalarExpr(init);
break;
case Qualifiers::OCL_Strong: {
value = EmitARCRetainScalarExpr(init);
break;
}
case Qualifiers::OCL_Weak: {
// No way to optimize a producing initializer into this. It's not
// worth optimizing for, because the value will immediately
// disappear in the common case.
value = EmitScalarExpr(init);
if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
if (accessedByInit)
EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true);
else
EmitARCInitWeak(lvalue.getAddress(), value);
return;
}
case Qualifiers::OCL_Autoreleasing:
value = EmitARCRetainAutoreleaseScalarExpr(init);
break;
}
if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
// If the variable might have been accessed by its initializer, we
// might have to initialize with a barrier. We have to do this for
// both __weak and __strong, but __weak got filtered out above.
if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
llvm::Value *oldValue = EmitLoadOfScalar(lvalue);
EmitStoreOfScalar(value, lvalue);
EmitARCRelease(oldValue, /*precise*/ false);
return;
}
EmitStoreOfScalar(value, lvalue);
}
/// EmitScalarInit - Initialize the given lvalue with the given object.
void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) {
Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
if (!lifetime)
return EmitStoreThroughLValue(RValue::get(init), lvalue);
switch (lifetime) {
case Qualifiers::OCL_None:
llvm_unreachable("present but none");
case Qualifiers::OCL_ExplicitNone:
// nothing to do
break;
case Qualifiers::OCL_Strong:
init = EmitARCRetain(lvalue.getType(), init);
break;
case Qualifiers::OCL_Weak:
// Initialize and then skip the primitive store.
EmitARCInitWeak(lvalue.getAddress(), init);
return;
case Qualifiers::OCL_Autoreleasing:
init = EmitARCRetainAutorelease(lvalue.getType(), init);
break;
}
EmitStoreOfScalar(init, lvalue);
}
/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
/// non-zero parts of the specified initializer with equal or fewer than
/// NumStores scalar stores.
static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
unsigned &NumStores) {
// Zero and Undef never requires any extra stores.
if (isa<llvm::ConstantAggregateZero>(Init) ||
isa<llvm::ConstantPointerNull>(Init) ||
isa<llvm::UndefValue>(Init))
return true;
if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
isa<llvm::ConstantExpr>(Init))
return Init->isNullValue() || NumStores--;
// See if we can emit each element.
if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
return false;
}
return true;
}
// Anything else is hard and scary.
return false;
}
/// emitStoresForInitAfterMemset - For inits that
/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
/// stores that would be required.
static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
bool isVolatile, CGBuilderTy &Builder) {
// Zero doesn't require any stores.
if (isa<llvm::ConstantAggregateZero>(Init) ||
isa<llvm::ConstantPointerNull>(Init) ||
isa<llvm::UndefValue>(Init))
return;
if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
isa<llvm::ConstantExpr>(Init)) {
if (!Init->isNullValue())
Builder.CreateStore(Init, Loc, isVolatile);
return;
}
assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
"Unknown value type!");
for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
if (Elt->isNullValue()) continue;
// Otherwise, get a pointer to the element and emit it.
emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
isVolatile, Builder);
}
}
/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
/// plus some stores to initialize a local variable instead of using a memcpy
/// from a constant global. It is beneficial to use memset if the global is all
/// zeros, or mostly zeros and large.
static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
uint64_t GlobalSize) {
// If a global is all zeros, always use a memset.
if (isa<llvm::ConstantAggregateZero>(Init)) return true;
// If a non-zero global is <= 32 bytes, always use a memcpy. If it is large,
// do it if it will require 6 or fewer scalar stores.
// TODO: Should budget depends on the size? Avoiding a large global warrants
// plopping in more stores.
unsigned StoreBudget = 6;
uint64_t SizeLimit = 32;
return GlobalSize > SizeLimit &&
canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
}
/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
/// variable declaration with auto, register, or no storage class specifier.
/// These turn into simple stack objects, or GlobalValues depending on target.
void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
AutoVarEmission emission = EmitAutoVarAlloca(D);
EmitAutoVarInit(emission);
EmitAutoVarCleanups(emission);
}
/// EmitAutoVarAlloca - Emit the alloca and debug information for a
/// local variable. Does not emit initalization or destruction.
CodeGenFunction::AutoVarEmission
CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
QualType Ty = D.getType();
AutoVarEmission emission(D);
bool isByRef = D.hasAttr<BlocksAttr>();
emission.IsByRef = isByRef;
CharUnits alignment = getContext().getDeclAlign(&D);
emission.Alignment = alignment;
// If the type is variably-modified, emit all the VLA sizes for it.
if (Ty->isVariablyModifiedType())
EmitVariablyModifiedType(Ty);
llvm::Value *DeclPtr;
if (Ty->isConstantSizeType()) {
if (!Target.useGlobalsForAutomaticVariables()) {
bool NRVO = getContext().getLangOptions().ElideConstructors &&
D.isNRVOVariable();
// If this value is a POD array or struct with a statically
// determinable constant initializer, there are optimizations we
// can do.
// TODO: we can potentially constant-evaluate non-POD structs and
// arrays as long as the initialization is trivial (e.g. if they
// have a non-trivial destructor, but not a non-trivial constructor).
if (D.getInit() &&
(Ty->isArrayType() || Ty->isRecordType()) &&
(Ty.isPODType(getContext()) ||
getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
D.getInit()->isConstantInitializer(getContext(), false)) {
// If the variable's a const type, and it's neither an NRVO
// candidate nor a __block variable, emit it as a global instead.
if (CGM.getCodeGenOpts().MergeAllConstants && Ty.isConstQualified() &&
!NRVO && !isByRef) {
EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
emission.Address = 0; // signal this condition to later callbacks
assert(emission.wasEmittedAsGlobal());
return emission;
}
// Otherwise, tell the initialization code that we're in this case.
emission.IsConstantAggregate = true;
}
// A normal fixed sized variable becomes an alloca in the entry block,
// unless it's an NRVO variable.
llvm::Type *LTy = ConvertTypeForMem(Ty);
if (NRVO) {
// The named return value optimization: allocate this variable in the
// return slot, so that we can elide the copy when returning this
// variable (C++0x [class.copy]p34).
DeclPtr = ReturnValue;
if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
// Create a flag that is used to indicate when the NRVO was applied
// to this variable. Set it to zero to indicate that NRVO was not
// applied.
llvm::Value *Zero = Builder.getFalse();
llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo");
EnsureInsertPoint();
Builder.CreateStore(Zero, NRVOFlag);
// Record the NRVO flag for this variable.
NRVOFlags[&D] = NRVOFlag;
emission.NRVOFlag = NRVOFlag;
}
}
} else {
if (isByRef)
LTy = BuildByRefType(&D);
llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
Alloc->setName(D.getNameAsString());
CharUnits allocaAlignment = alignment;
if (isByRef)
allocaAlignment = std::max(allocaAlignment,
getContext().toCharUnitsFromBits(Target.getPointerAlign(0)));
Alloc->setAlignment(allocaAlignment.getQuantity());
DeclPtr = Alloc;
}
} else {
// Targets that don't support recursion emit locals as globals.
const char *Class =
D.getStorageClass() == SC_Register ? ".reg." : ".auto.";
DeclPtr = CreateStaticVarDecl(D, Class,
llvm::GlobalValue::InternalLinkage);
}
} else {
EnsureInsertPoint();
if (!DidCallStackSave) {
// Save the stack.
llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack");
llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
llvm::Value *V = Builder.CreateCall(F);
Builder.CreateStore(V, Stack);
DidCallStackSave = true;
// Push a cleanup block and restore the stack there.
// FIXME: in general circumstances, this should be an EH cleanup.
EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack);
}
llvm::Value *elementCount;
QualType elementType;
llvm::tie(elementCount, elementType) = getVLASize(Ty);
llvm::Type *llvmTy = ConvertTypeForMem(elementType);
// Allocate memory for the array.
llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
vla->setAlignment(alignment.getQuantity());
DeclPtr = vla;
}
llvm::Value *&DMEntry = LocalDeclMap[&D];
assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
DMEntry = DeclPtr;
emission.Address = DeclPtr;
// Emit debug info for local var declaration.
if (HaveInsertPoint())
if (CGDebugInfo *DI = getDebugInfo()) {
DI->setLocation(D.getLocation());
if (Target.useGlobalsForAutomaticVariables()) {
DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D);
} else
DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
}
if (D.hasAttr<AnnotateAttr>())
EmitVarAnnotations(&D, emission.Address);
return emission;
}
/// Determines whether the given __block variable is potentially
/// captured by the given expression.
static bool isCapturedBy(const VarDecl &var, const Expr *e) {
// Skip the most common kinds of expressions that make
// hierarchy-walking expensive.
e = e->IgnoreParenCasts();
if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
const BlockDecl *block = be->getBlockDecl();
for (BlockDecl::capture_const_iterator i = block->capture_begin(),
e = block->capture_end(); i != e; ++i) {
if (i->getVariable() == &var)
return true;
}
// No need to walk into the subexpressions.
return false;
}
if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) {
const CompoundStmt *CS = SE->getSubStmt();
for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
BE = CS->body_end(); BI != BE; ++BI)
if (Expr *E = dyn_cast<Expr>((*BI))) {
if (isCapturedBy(var, E))
return true;
}
else if (DeclStmt *DS = dyn_cast<DeclStmt>((*BI))) {
// special case declarations
for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end();
I != E; ++I) {
if (VarDecl *VD = dyn_cast<VarDecl>((*I))) {
Expr *Init = VD->getInit();
if (Init && isCapturedBy(var, Init))
return true;
}
}
}
else
// FIXME. Make safe assumption assuming arbitrary statements cause capturing.
// Later, provide code to poke into statements for capture analysis.
return true;
return false;
}
for (Stmt::const_child_range children = e->children(); children; ++children)
if (isCapturedBy(var, cast<Expr>(*children)))
return true;
return false;
}
/// \brief Determine whether the given initializer is trivial in the sense
/// that it requires no code to be generated.
static bool isTrivialInitializer(const Expr *Init) {
if (!Init)
return true;
if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
if (CXXConstructorDecl *Constructor = Construct->getConstructor())
if (Constructor->isTrivial() &&
Constructor->isDefaultConstructor() &&
!Construct->requiresZeroInitialization())
return true;
return false;
}
void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
assert(emission.Variable && "emission was not valid!");
// If this was emitted as a global constant, we're done.
if (emission.wasEmittedAsGlobal()) return;
const VarDecl &D = *emission.Variable;
QualType type = D.getType();
// If this local has an initializer, emit it now.
const Expr *Init = D.getInit();
// If we are at an unreachable point, we don't need to emit the initializer
// unless it contains a label.
if (!HaveInsertPoint()) {
if (!Init || !ContainsLabel(Init)) return;
EnsureInsertPoint();
}
// Initialize the structure of a __block variable.
if (emission.IsByRef)
emitByrefStructureInit(emission);
if (isTrivialInitializer(Init))
return;
CharUnits alignment = emission.Alignment;
// Check whether this is a byref variable that's potentially
// captured and moved by its own initializer. If so, we'll need to
// emit the initializer first, then copy into the variable.
bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
llvm::Value *Loc =
capturedByInit ? emission.Address : emission.getObjectAddress(*this);
if (!emission.IsConstantAggregate) {
LValue lv = MakeAddrLValue(Loc, type, alignment.getQuantity());
lv.setNonGC(true);
return EmitExprAsInit(Init, &D, lv, capturedByInit);
}
// If this is a simple aggregate initialization, we can optimize it
// in various ways.
assert(!capturedByInit && "constant init contains a capturing block?");
bool isVolatile = type.isVolatileQualified();
llvm::Constant *constant = CGM.EmitConstantExpr(D.getInit(), type, this);
assert(constant != 0 && "Wasn't a simple constant init?");
llvm::Value *SizeVal =
llvm::ConstantInt::get(IntPtrTy,
getContext().getTypeSizeInChars(type).getQuantity());
llvm::Type *BP = Int8PtrTy;
if (Loc->getType() != BP)
Loc = Builder.CreateBitCast(Loc, BP);
// If the initializer is all or mostly zeros, codegen with memset then do
// a few stores afterward.
if (shouldUseMemSetPlusStoresToInitialize(constant,
CGM.getTargetData().getTypeAllocSize(constant->getType()))) {
Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
alignment.getQuantity(), isVolatile);
if (!constant->isNullValue()) {
Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder);
}
} else {
// Otherwise, create a temporary global with the initializer then
// memcpy from the global to the alloca.
std::string Name = GetStaticDeclName(*this, D, ".");
llvm::GlobalVariable *GV =
new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
llvm::GlobalValue::PrivateLinkage,
constant, Name, 0, false, 0);
GV->setAlignment(alignment.getQuantity());
GV->setUnnamedAddr(true);
llvm::Value *SrcPtr = GV;
if (SrcPtr->getType() != BP)
SrcPtr = Builder.CreateBitCast(SrcPtr, BP);
Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(),
isVolatile);
}
}
/// Emit an expression as an initializer for a variable at the given
/// location. The expression is not necessarily the normal
/// initializer for the variable, and the address is not necessarily
/// its normal location.
///
/// \param init the initializing expression
/// \param var the variable to act as if we're initializing
/// \param loc the address to initialize; its type is a pointer
/// to the LLVM mapping of the variable's type
/// \param alignment the alignment of the address
/// \param capturedByInit true if the variable is a __block variable
/// whose address is potentially changed by the initializer
void CodeGenFunction::EmitExprAsInit(const Expr *init,
const ValueDecl *D,
LValue lvalue,
bool capturedByInit) {
QualType type = D->getType();
if (type->isReferenceType()) {
RValue rvalue = EmitReferenceBindingToExpr(init, D);
if (capturedByInit)
drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
EmitStoreThroughLValue(rvalue, lvalue);
} else if (!hasAggregateLLVMType(type)) {
EmitScalarInit(init, D, lvalue, capturedByInit);
} else if (type->isAnyComplexType()) {
ComplexPairTy complex = EmitComplexExpr(init);
if (capturedByInit)
drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
StoreComplexToAddr(complex, lvalue.getAddress(), lvalue.isVolatile());
} else {
// TODO: how can we delay here if D is captured by its initializer?
EmitAggExpr(init, AggValueSlot::forLValue(lvalue,
AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased));
}
}
/// Enter a destroy cleanup for the given local variable.
void CodeGenFunction::emitAutoVarTypeCleanup(
const CodeGenFunction::AutoVarEmission &emission,
QualType::DestructionKind dtorKind) {
assert(dtorKind != QualType::DK_none);
// Note that for __block variables, we want to destroy the
// original stack object, not the possibly forwarded object.
llvm::Value *addr = emission.getObjectAddress(*this);
const VarDecl *var = emission.Variable;
QualType type = var->getType();
CleanupKind cleanupKind = NormalAndEHCleanup;
CodeGenFunction::Destroyer *destroyer = 0;
switch (dtorKind) {
case QualType::DK_none:
llvm_unreachable("no cleanup for trivially-destructible variable");
case QualType::DK_cxx_destructor:
// If there's an NRVO flag on the emission, we need a different
// cleanup.
if (emission.NRVOFlag) {
assert(!type->isArrayType());
CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor,
emission.NRVOFlag);
return;
}
break;
case QualType::DK_objc_strong_lifetime:
// Suppress cleanups for pseudo-strong variables.
if (var->isARCPseudoStrong()) return;
// Otherwise, consider whether to use an EH cleanup or not.
cleanupKind = getARCCleanupKind();
// Use the imprecise destroyer by default.
if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
destroyer = CodeGenFunction::destroyARCStrongImprecise;
break;
case QualType::DK_objc_weak_lifetime:
break;
}
// If we haven't chosen a more specific destroyer, use the default.
if (!destroyer) destroyer = &getDestroyer(dtorKind);
// Use an EH cleanup in array destructors iff the destructor itself
// is being pushed as an EH cleanup.
bool useEHCleanup = (cleanupKind & EHCleanup);
EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
useEHCleanup);
}
void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
assert(emission.Variable && "emission was not valid!");
// If this was emitted as a global constant, we're done.
if (emission.wasEmittedAsGlobal()) return;
const VarDecl &D = *emission.Variable;
// Check the type for a cleanup.
if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
emitAutoVarTypeCleanup(emission, dtorKind);
// In GC mode, honor objc_precise_lifetime.
if (getLangOptions().getGC() != LangOptions::NonGC &&
D.hasAttr<ObjCPreciseLifetimeAttr>()) {
EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
}
// Handle the cleanup attribute.
if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
const FunctionDecl *FD = CA->getFunctionDecl();
llvm::Constant *F = CGM.GetAddrOfFunction(FD);
assert(F && "Could not find function!");
const CGFunctionInfo &Info = CGM.getTypes().getFunctionInfo(FD);
EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
}
// If this is a block variable, call _Block_object_destroy
// (on the unforwarded address).
if (emission.IsByRef)
enterByrefCleanup(emission);
}
CodeGenFunction::Destroyer &
CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
// This is surprisingly compiler-dependent. GCC 4.2 can't bind
// references to functions directly in returns, and using '*&foo'
// confuses MSVC. Luckily, the following code pattern works in both.
Destroyer *destroyer = 0;
switch (kind) {
case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
case QualType::DK_cxx_destructor:
destroyer = &destroyCXXObject;
break;
case QualType::DK_objc_strong_lifetime:
destroyer = &destroyARCStrongPrecise;
break;
case QualType::DK_objc_weak_lifetime:
destroyer = &destroyARCWeak;
break;
}
return *destroyer;
}
/// pushDestroy - Push the standard destructor for the given type.
void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
llvm::Value *addr, QualType type) {
assert(dtorKind && "cannot push destructor for trivial type");
CleanupKind cleanupKind = getCleanupKind(dtorKind);
pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
cleanupKind & EHCleanup);
}
void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr,
QualType type, Destroyer &destroyer,
bool useEHCleanupForArray) {
pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
destroyer, useEHCleanupForArray);
}
/// emitDestroy - Immediately perform the destruction of the given
/// object.
///
/// \param addr - the address of the object; a type*
/// \param type - the type of the object; if an array type, all
/// objects are destroyed in reverse order
/// \param destroyer - the function to call to destroy individual
/// elements
/// \param useEHCleanupForArray - whether an EH cleanup should be
/// used when destroying array elements, in case one of the
/// destructions throws an exception
void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type,
Destroyer &destroyer,
bool useEHCleanupForArray) {
const ArrayType *arrayType = getContext().getAsArrayType(type);
if (!arrayType)
return destroyer(*this, addr, type);
llvm::Value *begin = addr;
llvm::Value *length = emitArrayLength(arrayType, type, begin);
// Normally we have to check whether the array is zero-length.
bool checkZeroLength = true;
// But if the array length is constant, we can suppress that.
if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
// ...and if it's constant zero, we can just skip the entire thing.
if (constLength->isZero()) return;
checkZeroLength = false;
}
llvm::Value *end = Builder.CreateInBoundsGEP(begin, length);
emitArrayDestroy(begin, end, type, destroyer,
checkZeroLength, useEHCleanupForArray);
}
/// emitArrayDestroy - Destroys all the elements of the given array,
/// beginning from last to first. The array cannot be zero-length.
///
/// \param begin - a type* denoting the first element of the array
/// \param end - a type* denoting one past the end of the array
/// \param type - the element type of the array
/// \param destroyer - the function to call to destroy elements
/// \param useEHCleanup - whether to push an EH cleanup to destroy
/// the remaining elements in case the destruction of a single
/// element throws
void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
llvm::Value *end,
QualType type,
Destroyer &destroyer,
bool checkZeroLength,
bool useEHCleanup) {
assert(!type->isArrayType());
// The basic structure here is a do-while loop, because we don't
// need to check for the zero-element case.
llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
if (checkZeroLength) {
llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
"arraydestroy.isempty");
Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
}
// Enter the loop body, making that address the current address.
llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
EmitBlock(bodyBB);
llvm::PHINode *elementPast =
Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
elementPast->addIncoming(end, entryBB);
// Shift the address back by one element.
llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne,
"arraydestroy.element");
if (useEHCleanup)
pushRegularPartialArrayCleanup(begin, element, type, destroyer);
// Perform the actual destruction there.
destroyer(*this, element, type);
if (useEHCleanup)
PopCleanupBlock();
// Check whether we've reached the end.
llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
Builder.CreateCondBr(done, doneBB, bodyBB);
elementPast->addIncoming(element, Builder.GetInsertBlock());
// Done.
EmitBlock(doneBB);
}
/// Perform partial array destruction as if in an EH cleanup. Unlike
/// emitArrayDestroy, the element type here may still be an array type.
static void emitPartialArrayDestroy(CodeGenFunction &CGF,
llvm::Value *begin, llvm::Value *end,
QualType type,
CodeGenFunction::Destroyer &destroyer) {
// If the element type is itself an array, drill down.
unsigned arrayDepth = 0;
while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
// VLAs don't require a GEP index to walk into.
if (!isa<VariableArrayType>(arrayType))
arrayDepth++;
type = arrayType->getElementType();
}
if (arrayDepth) {
llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1);
SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero);
begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend");
}
// Destroy the array. We don't ever need an EH cleanup because we
// assume that we're in an EH cleanup ourselves, so a throwing
// destructor causes an immediate terminate.
CGF.emitArrayDestroy(begin, end, type, destroyer,
/*checkZeroLength*/ true, /*useEHCleanup*/ false);
}
namespace {
/// RegularPartialArrayDestroy - a cleanup which performs a partial
/// array destroy where the end pointer is regularly determined and
/// does not need to be loaded from a local.
class RegularPartialArrayDestroy : public EHScopeStack::Cleanup {
llvm::Value *ArrayBegin;
llvm::Value *ArrayEnd;
QualType ElementType;
CodeGenFunction::Destroyer &Destroyer;
public:
RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
QualType elementType,
CodeGenFunction::Destroyer *destroyer)
: ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
ElementType(elementType), Destroyer(*destroyer) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
ElementType, Destroyer);
}
};
/// IrregularPartialArrayDestroy - a cleanup which performs a
/// partial array destroy where the end pointer is irregularly
/// determined and must be loaded from a local.
class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup {
llvm::Value *ArrayBegin;
llvm::Value *ArrayEndPointer;
QualType ElementType;
CodeGenFunction::Destroyer &Destroyer;
public:
IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
llvm::Value *arrayEndPointer,
QualType elementType,
CodeGenFunction::Destroyer *destroyer)
: ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
ElementType(elementType), Destroyer(*destroyer) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
ElementType, Destroyer);
}
};
}
/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
/// already-constructed elements of the given array. The cleanup
/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
///
/// \param elementType - the immediate element type of the array;
/// possibly still an array type
/// \param array - a value of type elementType*
/// \param destructionKind - the kind of destruction required
/// \param initializedElementCount - a value of type size_t* holding
/// the number of successfully-constructed elements
void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
llvm::Value *arrayEndPointer,
QualType elementType,
Destroyer &destroyer) {
pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup,
arrayBegin, arrayEndPointer,
elementType, &destroyer);
}
/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
/// already-constructed elements of the given array. The cleanup
/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
///
/// \param elementType - the immediate element type of the array;
/// possibly still an array type
/// \param array - a value of type elementType*
/// \param destructionKind - the kind of destruction required
/// \param initializedElementCount - a value of type size_t* holding
/// the number of successfully-constructed elements
void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
llvm::Value *arrayEnd,
QualType elementType,
Destroyer &destroyer) {
pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup,
arrayBegin, arrayEnd,
elementType, &destroyer);
}
namespace {
/// A cleanup to perform a release of an object at the end of a
/// function. This is used to balance out the incoming +1 of a
/// ns_consumed argument when we can't reasonably do that just by
/// not doing the initial retain for a __block argument.
struct ConsumeARCParameter : EHScopeStack::Cleanup {
ConsumeARCParameter(llvm::Value *param) : Param(param) {}
llvm::Value *Param;
void Emit(CodeGenFunction &CGF, Flags flags) {
CGF.EmitARCRelease(Param, /*precise*/ false);
}
};
}
/// Emit an alloca (or GlobalValue depending on target)
/// for the specified parameter and set up LocalDeclMap.
void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
unsigned ArgNo) {
// FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
"Invalid argument to EmitParmDecl");
Arg->setName(D.getName());
// Use better IR generation for certain implicit parameters.
if (isa<ImplicitParamDecl>(D)) {
// The only implicit argument a block has is its literal.
if (BlockInfo) {
LocalDeclMap[&D] = Arg;
if (CGDebugInfo *DI = getDebugInfo()) {
DI->setLocation(D.getLocation());
DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder);
}
return;
}
}
QualType Ty = D.getType();
llvm::Value *DeclPtr;
// If this is an aggregate or variable sized value, reuse the input pointer.
if (!Ty->isConstantSizeType() ||
CodeGenFunction::hasAggregateLLVMType(Ty)) {
DeclPtr = Arg;
} else {
// Otherwise, create a temporary to hold the value.
llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
D.getName() + ".addr");
Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity());
DeclPtr = Alloc;
bool doStore = true;
Qualifiers qs = Ty.getQualifiers();
if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
// We honor __attribute__((ns_consumed)) for types with lifetime.
// For __strong, it's handled by just skipping the initial retain;
// otherwise we have to balance out the initial +1 with an extra
// cleanup to do the release at the end of the function.
bool isConsumed = D.hasAttr<NSConsumedAttr>();
// 'self' is always formally __strong, but if this is not an
// init method then we don't want to retain it.
if (D.isARCPseudoStrong()) {
const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
assert(&D == method->getSelfDecl());
assert(lt == Qualifiers::OCL_Strong);
assert(qs.hasConst());
assert(method->getMethodFamily() != OMF_init);
(void) method;
lt = Qualifiers::OCL_ExplicitNone;
}
if (lt == Qualifiers::OCL_Strong) {
if (!isConsumed)
// Don't use objc_retainBlock for block pointers, because we
// don't want to Block_copy something just because we got it
// as a parameter.
Arg = EmitARCRetainNonBlock(Arg);
} else {
// Push the cleanup for a consumed parameter.
if (isConsumed)
EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg);
if (lt == Qualifiers::OCL_Weak) {
EmitARCInitWeak(DeclPtr, Arg);
doStore = false; // The weak init is a store, no need to do two
}
}
// Enter the cleanup scope.
EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
}
// Store the initial value into the alloca.
if (doStore) {
LValue lv = MakeAddrLValue(DeclPtr, Ty,
getContext().getDeclAlign(&D).getQuantity());
EmitStoreOfScalar(Arg, lv);
}
}
llvm::Value *&DMEntry = LocalDeclMap[&D];
assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
DMEntry = DeclPtr;
// Emit debug info for param declaration.
if (CGDebugInfo *DI = getDebugInfo())
DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder);
if (D.hasAttr<AnnotateAttr>())
EmitVarAnnotations(&D, DeclPtr);
}
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