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llvm-project/clang/lib/CodeGen/CGDecl.cpp
John McCall a5efa7386a Track whether an AggValueSlot is potentially aliased, and do not 
emit call results into potentially aliased slots.  This allows us
to properly mark indirect return slots as noalias, at the cost
of requiring an extra memcpy when assigning an aggregate call
result into a l-value.  It also brings us into compliance with
the x86-64 ABI.

llvm-svn: 138599
2011-08-25 23:04:34 +00:00

1506 lines
55 KiB
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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 "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:
assert(0 && "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;
}
assert(0 && "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
assert(0 && "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
assert(0 && "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());
// FIXME: Merge attribute handling.
if (const AnnotateAttr *AA = D.getAttr<AnnotateAttr>()) {
SourceManager &SM = CGM.getContext().getSourceManager();
llvm::Constant *Ann =
CGM.EmitAnnotateAttr(GV, AA, SM.getExpansionLineNumber(D.getLocation()));
CGM.AddAnnotation(Ann);
}
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, "tmp");
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.
CodeGenFunction::RunCleanupsScope Scope(*this);
if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init))
init = ewc->getSubExpr();
// 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);
}
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, "tmp");
// 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, "tmp");
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().getGCMode() != 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.
DeclPtr = CreateMemTemp(Ty, D.getName() + ".addr");
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);
}
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