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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 "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclObjC.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.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()) {
default: assert(0 && "Unknown decl kind!");
case Decl::ParmVar:
assert(0 && "Parmdecls 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++]
// None of these decls require codegen support.
return;
case Decl::Var: {
const VarDecl &VD = cast<VarDecl>(D);
assert(VD.isBlockVarDecl() &&
"Should not see file-scope variables inside a function!");
return EmitBlockVarDecl(VD);
}
case Decl::Typedef: { // typedef int X;
const TypedefDecl &TD = cast<TypedefDecl>(D);
QualType Ty = TD.getUnderlyingType();
if (Ty->isVariablyModifiedType())
EmitVLASize(Ty);
}
}
}
/// EmitBlockVarDecl - This method handles emission of any variable declaration
/// inside a function, including static vars etc.
void CodeGenFunction::EmitBlockVarDecl(const VarDecl &D) {
if (D.hasAttr<AsmLabelAttr>())
CGM.ErrorUnsupported(&D, "__asm__");
switch (D.getStorageClass()) {
case VarDecl::None:
case VarDecl::Auto:
case VarDecl::Register:
return EmitLocalBlockVarDecl(D);
case VarDecl::Static:
return EmitStaticBlockVarDecl(D);
case VarDecl::Extern:
case VarDecl::PrivateExtern:
// Don't emit it now, allow it to be emitted lazily on its first use.
return;
}
assert(0 && "Unknown storage class");
}
llvm::GlobalVariable *
CodeGenFunction::CreateStaticBlockVarDecl(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;
if (getContext().getLangOptions().CPlusPlus) {
Name = CGM.getMangledName(&D);
} else {
std::string ContextName;
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CurFuncDecl))
ContextName = CGM.getMangledName(FD);
else if (isa<ObjCMethodDecl>(CurFuncDecl))
ContextName = std::string(CurFn->getNameStart(),
CurFn->getNameStart() + CurFn->getNameLen());
else
assert(0 && "Unknown context for block var decl");
Name = ContextName + Separator + D.getNameAsString();
}
const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
return new llvm::GlobalVariable(CGM.getModule().getContext(),
LTy, Ty.isConstant(getContext()), Linkage,
llvm::Constant::getNullValue(LTy), Name,
&CGM.getModule(), D.isThreadSpecified(),
Ty.getAddressSpace());
}
void CodeGenFunction::EmitStaticBlockVarDecl(const VarDecl &D) {
llvm::Value *&DMEntry = LocalDeclMap[&D];
assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
llvm::GlobalVariable *GV =
CreateStaticBlockVarDecl(D, ".", llvm::GlobalValue::InternalLinkage);
// Store into LocalDeclMap before generating initializer to handle
// circular references.
DMEntry = GV;
// Make sure to evaluate VLA bounds now so that we have them for later.
if (D.getType()->isVariablyModifiedType())
EmitVLASize(D.getType());
if (D.getType()->isReferenceType()) {
CGM.ErrorUnsupported(&D, "static declaration with reference type");
return;
}
if (D.getInit()) {
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
GenerateStaticCXXBlockVarDeclInit(D, GV);
} else {
// 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() != Init->getType()) {
llvm::GlobalVariable *OldGV = GV;
GV = new llvm::GlobalVariable(CGM.getModule().getContext(),
Init->getType(), OldGV->isConstant(),
OldGV->getLinkage(), Init, "",
&CGM.getModule(), D.isThreadSpecified(),
D.getType().getAddressSpace());
// 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);
}
}
// FIXME: Merge attribute handling.
if (const AnnotateAttr *AA = D.getAttr<AnnotateAttr>()) {
SourceManager &SM = CGM.getContext().getSourceManager();
llvm::Constant *Ann =
CGM.EmitAnnotateAttr(GV, AA,
SM.getInstantiationLineNumber(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.
const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(D.getType());
const llvm::Type *LPtrTy =
llvm::PointerType::get(LTy, D.getType().getAddressSpace());
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);
}
}
/// BuildByRefType - This routine changes a __block variable declared as T x
/// into:
///
/// struct {
/// void *__isa;
/// void *__forwarding;
/// int32_t __flags;
/// int32_t __size;
/// void *__copy_helper;
/// void *__destroy_helper;
/// T x;
/// } x
///
/// Align is the alignment needed in bytes for x.
const llvm::Type *CodeGenFunction::BuildByRefType(QualType Ty,
uint64_t Align) {
const llvm::Type *LTy = ConvertType(Ty);
bool needsCopyDispose = BlockRequiresCopying(Ty);
std::vector<const llvm::Type *> Types(needsCopyDispose*2+5);
const llvm::PointerType *PtrToInt8Ty
= llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
Types[0] = PtrToInt8Ty;
Types[1] = PtrToInt8Ty;
Types[2] = llvm::Type::Int32Ty;
Types[3] = llvm::Type::Int32Ty;
if (needsCopyDispose) {
Types[4] = PtrToInt8Ty;
Types[5] = PtrToInt8Ty;
}
// FIXME: Align this on at least an Align boundary, assert if we can't.
assert((Align <= unsigned(Target.getPointerAlign(0))/8)
&& "Can't align more than pointer yet");
Types[needsCopyDispose*2 + 4] = LTy;
return llvm::StructType::get(Types, false);
}
/// EmitLocalBlockVarDecl - 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::EmitLocalBlockVarDecl(const VarDecl &D) {
QualType Ty = D.getType();
bool isByRef = D.hasAttr<BlocksAttr>();
bool needsDispose = false;
unsigned Align = 0;
llvm::Value *DeclPtr;
if (Ty->isConstantSizeType()) {
if (!Target.useGlobalsForAutomaticVariables()) {
// A normal fixed sized variable becomes an alloca in the entry block.
const llvm::Type *LTy = ConvertTypeForMem(Ty);
Align = getContext().getDeclAlignInBytes(&D);
if (isByRef)
LTy = BuildByRefType(Ty, Align);
llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
Alloc->setName(D.getNameAsString().c_str());
if (isByRef)
Align = std::max(Align, unsigned(Target.getPointerAlign(0) / 8));
Alloc->setAlignment(Align);
DeclPtr = Alloc;
} else {
// Targets that don't support recursion emit locals as globals.
const char *Class =
D.getStorageClass() == VarDecl::Register ? ".reg." : ".auto.";
DeclPtr = CreateStaticBlockVarDecl(D, Class,
llvm::GlobalValue
::InternalLinkage);
}
if (Ty->isVariablyModifiedType())
EmitVLASize(Ty);
} else {
if (!DidCallStackSave) {
// Save the stack.
const llvm::Type *LTy = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
llvm::Value *Stack = CreateTempAlloca(LTy, "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.
CleanupScope scope(*this);
V = Builder.CreateLoad(Stack, "tmp");
llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
Builder.CreateCall(F, V);
}
}
// Get the element type.
const llvm::Type *LElemTy = ConvertTypeForMem(Ty);
const llvm::Type *LElemPtrTy =
llvm::PointerType::get(LElemTy, D.getType().getAddressSpace());
llvm::Value *VLASize = EmitVLASize(Ty);
// Downcast the VLA size expression
VLASize = Builder.CreateIntCast(VLASize, llvm::Type::Int32Ty, false, "tmp");
// Allocate memory for the array.
llvm::Value *VLA = Builder.CreateAlloca(llvm::Type::Int8Ty, VLASize, "vla");
DeclPtr = Builder.CreateBitCast(VLA, LElemPtrTy, "tmp");
}
llvm::Value *&DMEntry = LocalDeclMap[&D];
assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
DMEntry = DeclPtr;
// Emit debug info for local var declaration.
if (CGDebugInfo *DI = getDebugInfo()) {
DI->setLocation(D.getLocation());
if (Target.useGlobalsForAutomaticVariables()) {
DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D);
}
else if (isByRef) {
llvm::Value *Loc;
bool needsCopyDispose = BlockRequiresCopying(Ty);
Loc = Builder.CreateStructGEP(DeclPtr, 1, "forwarding");
Loc = Builder.CreateLoad(Loc, false);
Loc = Builder.CreateBitCast(Loc, DeclPtr->getType());
Loc = Builder.CreateStructGEP(Loc, needsCopyDispose*2+4, "x");
DI->EmitDeclareOfAutoVariable(&D, Loc, Builder);
} else
DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
}
// If this local has an initializer, emit it now.
if (const Expr *Init = D.getInit()) {
llvm::Value *Loc = DeclPtr;
if (isByRef) {
bool needsCopyDispose = BlockRequiresCopying(Ty);
Loc = Builder.CreateStructGEP(DeclPtr, needsCopyDispose*2+4, "x");
}
if (Ty->isReferenceType()) {
llvm::Value *V = EmitReferenceBindingToExpr(Init, Ty).getScalarVal();
EmitStoreOfScalar(V, Loc, false, Ty);
} else if (!hasAggregateLLVMType(Init->getType())) {
llvm::Value *V = EmitScalarExpr(Init);
EmitStoreOfScalar(V, Loc, D.getType().isVolatileQualified(),
D.getType());
} else if (Init->getType()->isAnyComplexType()) {
EmitComplexExprIntoAddr(Init, Loc, D.getType().isVolatileQualified());
} else {
EmitAggExpr(Init, Loc, D.getType().isVolatileQualified());
}
}
if (isByRef) {
const llvm::PointerType *PtrToInt8Ty
= llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
llvm::Value *isa_field = Builder.CreateStructGEP(DeclPtr, 0);
llvm::Value *forwarding_field = Builder.CreateStructGEP(DeclPtr, 1);
llvm::Value *flags_field = Builder.CreateStructGEP(DeclPtr, 2);
llvm::Value *size_field = Builder.CreateStructGEP(DeclPtr, 3);
llvm::Value *V;
int flag = 0;
int flags = 0;
needsDispose = true;
if (Ty->isBlockPointerType()) {
flag |= BLOCK_FIELD_IS_BLOCK;
flags |= BLOCK_HAS_COPY_DISPOSE;
} else if (BlockRequiresCopying(Ty)) {
flag |= BLOCK_FIELD_IS_OBJECT;
flags |= BLOCK_HAS_COPY_DISPOSE;
}
// FIXME: Someone double check this.
if (Ty.isObjCGCWeak())
flag |= BLOCK_FIELD_IS_WEAK;
int isa = 0;
if (flag&BLOCK_FIELD_IS_WEAK)
isa = 1;
V = llvm::ConstantInt::get(llvm::Type::Int32Ty, isa);
V = Builder.CreateIntToPtr(V, PtrToInt8Ty, "isa");
Builder.CreateStore(V, isa_field);
V = Builder.CreateBitCast(DeclPtr, PtrToInt8Ty, "forwarding");
Builder.CreateStore(V, forwarding_field);
V = llvm::ConstantInt::get(llvm::Type::Int32Ty, flags);
Builder.CreateStore(V, flags_field);
const llvm::Type *V1;
V1 = cast<llvm::PointerType>(DeclPtr->getType())->getElementType();
V = llvm::ConstantInt::get(llvm::Type::Int32Ty,
(CGM.getTargetData().getTypeStoreSizeInBits(V1)
/ 8));
Builder.CreateStore(V, size_field);
if (flags & BLOCK_HAS_COPY_DISPOSE) {
BlockHasCopyDispose = true;
llvm::Value *copy_helper = Builder.CreateStructGEP(DeclPtr, 4);
Builder.CreateStore(BuildbyrefCopyHelper(DeclPtr->getType(), flag, Align),
copy_helper);
llvm::Value *destroy_helper = Builder.CreateStructGEP(DeclPtr, 5);
Builder.CreateStore(BuildbyrefDestroyHelper(DeclPtr->getType(), flag,
Align),
destroy_helper);
}
}
// Handle the cleanup attribute
if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
const FunctionDecl *FD = CA->getFunctionDecl();
llvm::Constant* F = CGM.GetAddrOfFunction(GlobalDecl(FD));
assert(F && "Could not find function!");
CleanupScope scope(*this);
const CGFunctionInfo &Info = CGM.getTypes().getFunctionInfo(FD);
// 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 = Info.arg_begin()->type;
DeclPtr = Builder.CreateBitCast(DeclPtr, ConvertType(ArgTy));
CallArgList Args;
Args.push_back(std::make_pair(RValue::get(DeclPtr),
getContext().getPointerType(D.getType())));
EmitCall(Info, F, Args);
}
if (needsDispose && CGM.getLangOptions().getGCMode() != LangOptions::GCOnly) {
CleanupScope scope(*this);
llvm::Value *V = Builder.CreateStructGEP(DeclPtr, 1, "forwarding");
V = Builder.CreateLoad(V, false);
BuildBlockRelease(V);
}
}
/// 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) {
// FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
"Invalid argument to EmitParmDecl");
QualType Ty = D.getType();
llvm::Value *DeclPtr;
if (!Ty->isConstantSizeType()) {
// Variable sized values always are passed by-reference.
DeclPtr = Arg;
} else {
// A fixed sized single-value variable becomes an alloca in the entry block.
const llvm::Type *LTy = ConvertTypeForMem(Ty);
if (LTy->isSingleValueType()) {
// TODO: Alignment
std::string Name = D.getNameAsString();
Name += ".addr";
DeclPtr = CreateTempAlloca(LTy);
DeclPtr->setName(Name.c_str());
// Store the initial value into the alloca.
EmitStoreOfScalar(Arg, DeclPtr, Ty.isVolatileQualified(), Ty);
} else {
// Otherwise, if this is an aggregate, just use the input pointer.
DeclPtr = Arg;
}
Arg->setName(D.getNameAsString());
}
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->setLocation(D.getLocation());
DI->EmitDeclareOfArgVariable(&D, DeclPtr, Builder);
}
}
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