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+//===-- CGValue.h - LLVM CodeGen wrappers for llvm::Value* ------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// 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;
+
+public:
+ explicit LValueBaseInfo(AlignmentSource Source = AlignmentSource::Type)
+ : AlignSource(Source) {}
+ AlignmentSource getAlignmentSource() const { return AlignSource; }
+ void setAlignmentSource(AlignmentSource Source) { AlignSource = Source; }
+
+ void mergeForCast(const LValueBaseInfo &Info) {
+ setAlignmentSource(Info.getAlignmentSource());
+ }
+};
+
+/// 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.)
+ unsigned 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;
+
+ // This flag shows if a nontemporal load/stores should be used when accessing
+ // this lvalue.
+ bool Nontemporal : 1;
+
+ LValueBaseInfo BaseInfo;
+ TBAAAccessInfo TBAAInfo;
+
+ Expr *BaseIvarExp;
+
+private:
+ void Initialize(QualType Type, Qualifiers Quals, CharUnits Alignment,
+ LValueBaseInfo BaseInfo, TBAAAccessInfo TBAAInfo) {
+ assert((!Alignment.isZero() || Type->isIncompleteType()) &&
+ "initializing l-value with zero alignment!");
+ this->Type = Type;
+ this->Quals = Quals;
+ const unsigned MaxAlign = 1U << 31;
+ this->Alignment = Alignment.getQuantity() <= MaxAlign
+ ? Alignment.getQuantity()
+ : MaxAlign;
+ assert(this->Alignment == Alignment.getQuantity() &&
+ "Alignment exceeds allowed max!");
+ this->BaseInfo = BaseInfo;
+ this->TBAAInfo = TBAAInfo;
+
+ // 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; }
+
+ const Qualifiers &getQuals() const { return Quals; }
+ Qualifiers &getQuals() { return Quals; }
+
+ LangAS 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, TBAAAccessInfo TBAAInfo) {
+ 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, TBAAInfo);
+ return R;
+ }
+
+ static LValue MakeVectorElt(Address vecAddress, llvm::Value *Idx,
+ QualType type, LValueBaseInfo BaseInfo,
+ TBAAAccessInfo TBAAInfo) {
+ LValue R;
+ R.LVType = VectorElt;
+ R.V = vecAddress.getPointer();
+ R.VectorIdx = Idx;
+ R.Initialize(type, type.getQualifiers(), vecAddress.getAlignment(),
+ BaseInfo, TBAAInfo);
+ return R;
+ }
+
+ static LValue MakeExtVectorElt(Address vecAddress, llvm::Constant *Elts,
+ QualType type, LValueBaseInfo BaseInfo,
+ TBAAAccessInfo TBAAInfo) {
+ LValue R;
+ R.LVType = ExtVectorElt;
+ R.V = vecAddress.getPointer();
+ R.VectorElts = Elts;
+ R.Initialize(type, type.getQualifiers(), vecAddress.getAlignment(),
+ BaseInfo, TBAAInfo);
+ return R;
+ }
+
+ /// 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,
+ TBAAAccessInfo TBAAInfo) {
+ LValue R;
+ R.LVType = BitField;
+ R.V = Addr.getPointer();
+ R.BitFieldInfo = &Info;
+ R.Initialize(type, type.getQualifiers(), Addr.getAlignment(), BaseInfo,
+ TBAAInfo);
+ 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), TBAAAccessInfo());
+ 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;
+
+ /// This is set to true if the tail padding of this slot might overlap
+ /// another object that may have already been initialized (and whose
+ /// value must be preserved by this initialization). If so, we may only
+ /// store up to the dsize of the type. Otherwise we can widen stores to
+ /// the size of the type.
+ bool OverlapFlag : 1;
+
+ /// If is set to true, sanitizer checks are already generated for this address
+ /// or not required. For instance, if this address represents an object
+ /// created in 'new' expression, sanitizer checks for memory is made as a part
+ /// of 'operator new' emission and object constructor should not generate
+ /// them.
+ bool SanitizerCheckedFlag : 1;
+
+public:
+ enum IsAliased_t { IsNotAliased, IsAliased };
+ enum IsDestructed_t { IsNotDestructed, IsDestructed };
+ enum IsZeroed_t { IsNotZeroed, IsZeroed };
+ enum Overlap_t { DoesNotOverlap, MayOverlap };
+ enum NeedsGCBarriers_t { DoesNotNeedGCBarriers, NeedsGCBarriers };
+ enum IsSanitizerChecked_t { IsNotSanitizerChecked, IsSanitizerChecked };
+
+ /// 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, DoesNotOverlap);
+ }
+
+ /// 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,
+ Overlap_t mayOverlap,
+ IsZeroed_t isZeroed = IsNotZeroed,
+ IsSanitizerChecked_t isChecked = IsNotSanitizerChecked) {
+ 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;
+ AV.OverlapFlag = mayOverlap;
+ AV.SanitizerCheckedFlag = isChecked;
+ return AV;
+ }
+
+ static AggValueSlot forLValue(const LValue &LV,
+ IsDestructed_t isDestructed,
+ NeedsGCBarriers_t needsGC,
+ IsAliased_t isAliased,
+ Overlap_t mayOverlap,
+ IsZeroed_t isZeroed = IsNotZeroed,
+ IsSanitizerChecked_t isChecked = IsNotSanitizerChecked) {
+ return forAddr(LV.getAddress(), LV.getQuals(), isDestructed, needsGC,
+ isAliased, mayOverlap, isZeroed, isChecked);
+ }
+
+ 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) {
+ if (flag)
+ Quals.addVolatile();
+ else
+ Quals.removeVolatile();
+ }
+
+ 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);
+ }
+
+ Overlap_t mayOverlap() const {
+ return Overlap_t(OverlapFlag);
+ }
+
+ bool isSanitizerChecked() const {
+ return SanitizerCheckedFlag;
+ }
+
+ 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);
+ }
+
+ /// Get the preferred size to use when storing a value to this slot. This
+ /// is the type size unless that might overlap another object, in which
+ /// case it's the dsize.
+ CharUnits getPreferredSize(ASTContext &Ctx, QualType Type) const {
+ return mayOverlap() ? Ctx.getTypeInfoDataSizeInChars(Type).first
+ : Ctx.getTypeSizeInChars(Type);
+ }
+};
+
+} // end namespace CodeGen
+} // end namespace clang
+
+#endif
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