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llvm-project/clang/lib/CodeGen/CGValue.h

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//===-- CGValue.h - LLVM CodeGen wrappers for llvm::Value* ------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// These classes implement wrappers around llvm::Value in order to
// fully represent the range of values for C L- and R- values.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_LIB_CODEGEN_CGVALUE_H
#define LLVM_CLANG_LIB_CODEGEN_CGVALUE_H
#include "clang/AST/ASTContext.h"
#include "clang/AST/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/IR/Type.h"
#include "Address.h"
#include "CodeGenTBAA.h"
namespace llvm {
class Constant;
class MDNode;
}
namespace clang {
namespace CodeGen {
class AggValueSlot;
struct CGBitFieldInfo;
/// RValue - This trivial value class is used to represent the result of an
/// expression that is evaluated. It can be one of three things: either a
/// simple LLVM SSA value, a pair of SSA values for complex numbers, or the
/// address of an aggregate value in memory.
class RValue {
enum Flavor { Scalar, Complex, Aggregate };
// The shift to make to an aggregate's alignment to make it look
// like a pointer.
enum { AggAlignShift = 4 };
// Stores first value and flavor.
llvm::PointerIntPair<llvm::Value *, 2, Flavor> V1;
// Stores second value and volatility.
llvm::PointerIntPair<llvm::Value *, 1, bool> V2;
public:
bool isScalar() const { return V1.getInt() == Scalar; }
bool isComplex() const { return V1.getInt() == Complex; }
bool isAggregate() const { return V1.getInt() == Aggregate; }
bool isVolatileQualified() const { return V2.getInt(); }
/// getScalarVal() - Return the Value* of this scalar value.
llvm::Value *getScalarVal() const {
assert(isScalar() && "Not a scalar!");
return V1.getPointer();
}
/// getComplexVal - Return the real/imag components of this complex value.
///
std::pair<llvm::Value *, llvm::Value *> getComplexVal() const {
return std::make_pair(V1.getPointer(), V2.getPointer());
}
/// getAggregateAddr() - Return the Value* of the address of the aggregate.
Address getAggregateAddress() const {
assert(isAggregate() && "Not an aggregate!");
auto align = reinterpret_cast<uintptr_t>(V2.getPointer()) >> AggAlignShift;
return Address(V1.getPointer(), CharUnits::fromQuantity(align));
}
llvm::Value *getAggregatePointer() const {
assert(isAggregate() && "Not an aggregate!");
return V1.getPointer();
}
static RValue getIgnored() {
// FIXME: should we make this a more explicit state?
return get(nullptr);
}
static RValue get(llvm::Value *V) {
RValue ER;
ER.V1.setPointer(V);
ER.V1.setInt(Scalar);
ER.V2.setInt(false);
return ER;
}
static RValue getComplex(llvm::Value *V1, llvm::Value *V2) {
RValue ER;
ER.V1.setPointer(V1);
ER.V2.setPointer(V2);
ER.V1.setInt(Complex);
ER.V2.setInt(false);
return ER;
}
static RValue getComplex(const std::pair<llvm::Value *, llvm::Value *> &C) {
return getComplex(C.first, C.second);
}
// FIXME: Aggregate rvalues need to retain information about whether they are
// volatile or not. Remove default to find all places that probably get this
// wrong.
static RValue getAggregate(Address addr, bool isVolatile = false) {
RValue ER;
ER.V1.setPointer(addr.getPointer());
ER.V1.setInt(Aggregate);
auto align = static_cast<uintptr_t>(addr.getAlignment().getQuantity());
ER.V2.setPointer(reinterpret_cast<llvm::Value*>(align << AggAlignShift));
ER.V2.setInt(isVolatile);
return ER;
}
};
/// Does an ARC strong l-value have precise lifetime?
enum ARCPreciseLifetime_t {
ARCImpreciseLifetime, ARCPreciseLifetime
};
/// The source of the alignment of an l-value; an expression of
/// confidence in the alignment actually matching the estimate.
enum class AlignmentSource {
/// The l-value was an access to a declared entity or something
/// equivalently strong, like the address of an array allocated by a
/// language runtime.
Decl,
/// The l-value was considered opaque, so the alignment was
/// determined from a type, but that type was an explicitly-aligned
/// typedef.
AttributedType,
/// The l-value was considered opaque, so the alignment was
/// determined from a type.
Type
};
/// Given that the base address has the given alignment source, what's
/// our confidence in the alignment of the field?
static inline AlignmentSource getFieldAlignmentSource(AlignmentSource Source) {
// For now, we don't distinguish fields of opaque pointers from
// top-level declarations, but maybe we should.
return AlignmentSource::Decl;
}
class LValueBaseInfo {
AlignmentSource AlignSource;
bool MayAlias;
public:
explicit LValueBaseInfo(AlignmentSource Source = AlignmentSource::Type,
bool Alias = false)
: AlignSource(Source), MayAlias(Alias) {}
AlignmentSource getAlignmentSource() const { return AlignSource; }
void setAlignmentSource(AlignmentSource Source) { AlignSource = Source; }
bool getMayAlias() const { return MayAlias; }
void setMayAlias(bool Alias) { MayAlias = Alias; }
void mergeForCast(const LValueBaseInfo &Info) {
setAlignmentSource(Info.getAlignmentSource());
setMayAlias(getMayAlias() || Info.getMayAlias());
}
};
/// LValue - This represents an lvalue references. Because C/C++ allow
/// bitfields, this is not a simple LLVM pointer, it may be a pointer plus a
/// bitrange.
class LValue {
enum {
Simple, // This is a normal l-value, use getAddress().
VectorElt, // This is a vector element l-value (V[i]), use getVector*
BitField, // This is a bitfield l-value, use getBitfield*.
ExtVectorElt, // This is an extended vector subset, use getExtVectorComp
GlobalReg // This is a register l-value, use getGlobalReg()
} LVType;
llvm::Value *V;
union {
// Index into a vector subscript: V[i]
llvm::Value *VectorIdx;
// ExtVector element subset: V.xyx
llvm::Constant *VectorElts;
// BitField start bit and size
const CGBitFieldInfo *BitFieldInfo;
};
QualType Type;
// 'const' is unused here
Qualifiers Quals;
// The alignment to use when accessing this lvalue. (For vector elements,
// this is the alignment of the whole vector.)
int64_t Alignment;
// objective-c's ivar
bool Ivar:1;
// objective-c's ivar is an array
bool ObjIsArray:1;
// LValue is non-gc'able for any reason, including being a parameter or local
// variable.
bool NonGC: 1;
// Lvalue is a global reference of an objective-c object
bool GlobalObjCRef : 1;
// Lvalue is a thread local reference
bool ThreadLocalRef : 1;
// Lvalue has ARC imprecise lifetime. We store this inverted to try
// to make the default bitfield pattern all-zeroes.
bool ImpreciseLifetime : 1;
LValueBaseInfo BaseInfo;
TBAAAccessInfo TBAAInfo;
// This flag shows if a nontemporal load/stores should be used when accessing
// this lvalue.
bool Nontemporal : 1;
Expr *BaseIvarExp;
private:
void Initialize(QualType Type, Qualifiers Quals,
CharUnits Alignment, LValueBaseInfo BaseInfo,
llvm::MDNode *TBAAAccessType = nullptr) {
assert((!Alignment.isZero() || Type->isIncompleteType()) &&
"initializing l-value with zero alignment!");
this->Type = Type;
this->Quals = Quals;
this->Alignment = Alignment.getQuantity();
assert(this->Alignment == Alignment.getQuantity() &&
"Alignment exceeds allowed max!");
this->BaseInfo = BaseInfo;
this->TBAAInfo = TBAAAccessInfo(Type, TBAAAccessType, /* Offset= */ 0);
// Initialize Objective-C flags.
this->Ivar = this->ObjIsArray = this->NonGC = this->GlobalObjCRef = false;
this->ImpreciseLifetime = false;
this->Nontemporal = false;
this->ThreadLocalRef = false;
this->BaseIvarExp = nullptr;
}
public:
bool isSimple() const { return LVType == Simple; }
bool isVectorElt() const { return LVType == VectorElt; }
bool isBitField() const { return LVType == BitField; }
bool isExtVectorElt() const { return LVType == ExtVectorElt; }
bool isGlobalReg() const { return LVType == GlobalReg; }
bool isVolatileQualified() const { return Quals.hasVolatile(); }
bool isRestrictQualified() const { return Quals.hasRestrict(); }
unsigned getVRQualifiers() const {
return Quals.getCVRQualifiers() & ~Qualifiers::Const;
}
QualType getType() const { return Type; }
Qualifiers::ObjCLifetime getObjCLifetime() const {
return Quals.getObjCLifetime();
}
bool isObjCIvar() const { return Ivar; }
void setObjCIvar(bool Value) { Ivar = Value; }
bool isObjCArray() const { return ObjIsArray; }
void setObjCArray(bool Value) { ObjIsArray = Value; }
bool isNonGC () const { return NonGC; }
void setNonGC(bool Value) { NonGC = Value; }
bool isGlobalObjCRef() const { return GlobalObjCRef; }
void setGlobalObjCRef(bool Value) { GlobalObjCRef = Value; }
bool isThreadLocalRef() const { return ThreadLocalRef; }
void setThreadLocalRef(bool Value) { ThreadLocalRef = Value;}
ARCPreciseLifetime_t isARCPreciseLifetime() const {
return ARCPreciseLifetime_t(!ImpreciseLifetime);
}
void setARCPreciseLifetime(ARCPreciseLifetime_t value) {
ImpreciseLifetime = (value == ARCImpreciseLifetime);
}
bool isNontemporal() const { return Nontemporal; }
void setNontemporal(bool Value) { Nontemporal = Value; }
bool isObjCWeak() const {
return Quals.getObjCGCAttr() == Qualifiers::Weak;
}
bool isObjCStrong() const {
return Quals.getObjCGCAttr() == Qualifiers::Strong;
}
bool isVolatile() const {
return Quals.hasVolatile();
}
Expr *getBaseIvarExp() const { return BaseIvarExp; }
void setBaseIvarExp(Expr *V) { BaseIvarExp = V; }
TBAAAccessInfo getTBAAInfo() const { return TBAAInfo; }
void setTBAAInfo(TBAAAccessInfo Info) { TBAAInfo = Info; }
llvm::MDNode *getTBAAAccessType() const { return TBAAInfo.AccessType; }
void setTBAAAccessType(llvm::MDNode *N) { TBAAInfo.AccessType = N; }
const Qualifiers &getQuals() const { return Quals; }
Qualifiers &getQuals() { return Quals; }
unsigned getAddressSpace() const { return Quals.getAddressSpace(); }
CharUnits getAlignment() const { return CharUnits::fromQuantity(Alignment); }
void setAlignment(CharUnits A) { Alignment = A.getQuantity(); }
LValueBaseInfo getBaseInfo() const { return BaseInfo; }
void setBaseInfo(LValueBaseInfo Info) { BaseInfo = Info; }
// simple lvalue
llvm::Value *getPointer() const {
assert(isSimple());
return V;
}
Address getAddress() const { return Address(getPointer(), getAlignment()); }
void setAddress(Address address) {
assert(isSimple());
V = address.getPointer();
Alignment = address.getAlignment().getQuantity();
}
// vector elt lvalue
Address getVectorAddress() const {
return Address(getVectorPointer(), getAlignment());
}
llvm::Value *getVectorPointer() const { assert(isVectorElt()); return V; }
llvm::Value *getVectorIdx() const { assert(isVectorElt()); return VectorIdx; }
// extended vector elements.
Address getExtVectorAddress() const {
return Address(getExtVectorPointer(), getAlignment());
}
llvm::Value *getExtVectorPointer() const {
assert(isExtVectorElt());
return V;
}
llvm::Constant *getExtVectorElts() const {
assert(isExtVectorElt());
return VectorElts;
}
// bitfield lvalue
Address getBitFieldAddress() const {
return Address(getBitFieldPointer(), getAlignment());
}
llvm::Value *getBitFieldPointer() const { assert(isBitField()); return V; }
const CGBitFieldInfo &getBitFieldInfo() const {
assert(isBitField());
return *BitFieldInfo;
}
// global register lvalue
llvm::Value *getGlobalReg() const { assert(isGlobalReg()); return V; }
static LValue MakeAddr(Address address, QualType type,
ASTContext &Context,
LValueBaseInfo BaseInfo,
llvm::MDNode *TBAAAccessType = nullptr) {
Qualifiers qs = type.getQualifiers();
qs.setObjCGCAttr(Context.getObjCGCAttrKind(type));
LValue R;
R.LVType = Simple;
assert(address.getPointer()->getType()->isPointerTy());
R.V = address.getPointer();
R.Initialize(type, qs, address.getAlignment(), BaseInfo, TBAAAccessType);
return R;
}
static LValue MakeVectorElt(Address vecAddress, llvm::Value *Idx,
QualType type, LValueBaseInfo BaseInfo) {
LValue R;
R.LVType = VectorElt;
R.V = vecAddress.getPointer();
R.VectorIdx = Idx;
R.Initialize(type, type.getQualifiers(), vecAddress.getAlignment(),
BaseInfo);
return R;
}
static LValue MakeExtVectorElt(Address vecAddress, llvm::Constant *Elts,
QualType type, LValueBaseInfo BaseInfo) {
LValue R;
R.LVType = ExtVectorElt;
R.V = vecAddress.getPointer();
R.VectorElts = Elts;
R.Initialize(type, type.getQualifiers(), vecAddress.getAlignment(),
BaseInfo);
return R;
}
/// \brief Create a new object to represent a bit-field access.
///
/// \param Addr - The base address of the bit-field sequence this
/// bit-field refers to.
/// \param Info - The information describing how to perform the bit-field
/// access.
static LValue MakeBitfield(Address Addr,
const CGBitFieldInfo &Info,
QualType type,
LValueBaseInfo BaseInfo) {
LValue R;
R.LVType = BitField;
R.V = Addr.getPointer();
R.BitFieldInfo = &Info;
R.Initialize(type, type.getQualifiers(), Addr.getAlignment(), BaseInfo);
return R;
}
static LValue MakeGlobalReg(Address Reg, QualType type) {
LValue R;
R.LVType = GlobalReg;
R.V = Reg.getPointer();
R.Initialize(type, type.getQualifiers(), Reg.getAlignment(),
LValueBaseInfo(AlignmentSource::Decl, false));
return R;
}
RValue asAggregateRValue() const {
return RValue::getAggregate(getAddress(), isVolatileQualified());
}
};
/// An aggregate value slot.
class AggValueSlot {
/// The address.
llvm::Value *Addr;
// Qualifiers
Qualifiers Quals;
unsigned Alignment;
/// DestructedFlag - This is set to true if some external code is
/// responsible for setting up a destructor for the slot. Otherwise
/// the code which constructs it should push the appropriate cleanup.
bool DestructedFlag : 1;
/// ObjCGCFlag - This is set to true if writing to the memory in the
/// slot might require calling an appropriate Objective-C GC
/// barrier. The exact interaction here is unnecessarily mysterious.
bool ObjCGCFlag : 1;
/// ZeroedFlag - This is set to true if the memory in the slot is
/// known to be zero before the assignment into it. This means that
/// zero fields don't need to be set.
bool ZeroedFlag : 1;
/// AliasedFlag - This is set to true if the slot might be aliased
/// and it's not undefined behavior to access it through such an
/// alias. Note that it's always undefined behavior to access a C++
/// object that's under construction through an alias derived from
/// outside the construction process.
///
/// This flag controls whether calls that produce the aggregate
/// value may be evaluated directly into the slot, or whether they
/// must be evaluated into an unaliased temporary and then memcpy'ed
/// over. Since it's invalid in general to memcpy a non-POD C++
/// object, it's important that this flag never be set when
/// evaluating an expression which constructs such an object.
bool AliasedFlag : 1;
public:
enum IsAliased_t { IsNotAliased, IsAliased };
enum IsDestructed_t { IsNotDestructed, IsDestructed };
enum IsZeroed_t { IsNotZeroed, IsZeroed };
enum NeedsGCBarriers_t { DoesNotNeedGCBarriers, NeedsGCBarriers };
/// ignored - Returns an aggregate value slot indicating that the
/// aggregate value is being ignored.
static AggValueSlot ignored() {
return forAddr(Address::invalid(), Qualifiers(), IsNotDestructed,
DoesNotNeedGCBarriers, IsNotAliased);
}
/// forAddr - Make a slot for an aggregate value.
///
/// \param quals - The qualifiers that dictate how the slot should
/// be initialied. Only 'volatile' and the Objective-C lifetime
/// qualifiers matter.
///
/// \param isDestructed - true if something else is responsible
/// for calling destructors on this object
/// \param needsGC - true if the slot is potentially located
/// somewhere that ObjC GC calls should be emitted for
static AggValueSlot forAddr(Address addr,
Qualifiers quals,
IsDestructed_t isDestructed,
NeedsGCBarriers_t needsGC,
IsAliased_t isAliased,
IsZeroed_t isZeroed = IsNotZeroed) {
AggValueSlot AV;
if (addr.isValid()) {
AV.Addr = addr.getPointer();
AV.Alignment = addr.getAlignment().getQuantity();
} else {
AV.Addr = nullptr;
AV.Alignment = 0;
}
AV.Quals = quals;
AV.DestructedFlag = isDestructed;
AV.ObjCGCFlag = needsGC;
AV.ZeroedFlag = isZeroed;
AV.AliasedFlag = isAliased;
return AV;
}
static AggValueSlot forLValue(const LValue &LV,
IsDestructed_t isDestructed,
NeedsGCBarriers_t needsGC,
IsAliased_t isAliased,
IsZeroed_t isZeroed = IsNotZeroed) {
return forAddr(LV.getAddress(),
LV.getQuals(), isDestructed, needsGC, isAliased, isZeroed);
}
IsDestructed_t isExternallyDestructed() const {
return IsDestructed_t(DestructedFlag);
}
void setExternallyDestructed(bool destructed = true) {
DestructedFlag = destructed;
}
Qualifiers getQualifiers() const { return Quals; }
bool isVolatile() const {
return Quals.hasVolatile();
}
void setVolatile(bool flag) {
Quals.setVolatile(flag);
}
Qualifiers::ObjCLifetime getObjCLifetime() const {
return Quals.getObjCLifetime();
}
NeedsGCBarriers_t requiresGCollection() const {
return NeedsGCBarriers_t(ObjCGCFlag);
}
llvm::Value *getPointer() const {
return Addr;
}
Address getAddress() const {
return Address(Addr, getAlignment());
}
bool isIgnored() const {
return Addr == nullptr;
}
CharUnits getAlignment() const {
return CharUnits::fromQuantity(Alignment);
}
IsAliased_t isPotentiallyAliased() const {
return IsAliased_t(AliasedFlag);
}
RValue asRValue() const {
if (isIgnored()) {
return RValue::getIgnored();
} else {
return RValue::getAggregate(getAddress(), isVolatile());
}
}
void setZeroed(bool V = true) { ZeroedFlag = V; }
IsZeroed_t isZeroed() const {
return IsZeroed_t(ZeroedFlag);
}
};
} // end namespace CodeGen
} // end namespace clang
#endif
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