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      1 //==- llvm/CodeGen/MachineMemOperand.h - MachineMemOperand class -*- C++ -*-==//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file contains the declaration of the MachineMemOperand class, which is a
     11 // description of a memory reference. It is used to help track dependencies
     12 // in the backend.
     13 //
     14 //===----------------------------------------------------------------------===//
     15 
     16 #ifndef LLVM_CODEGEN_MACHINEMEMOPERAND_H
     17 #define LLVM_CODEGEN_MACHINEMEMOPERAND_H
     18 
     19 #include "llvm/ADT/PointerUnion.h"
     20 #include "llvm/CodeGen/PseudoSourceValue.h"
     21 #include "llvm/IR/Value.h"  // PointerLikeTypeTraits<Value*>
     22 #include "llvm/Support/DataTypes.h"
     23 
     24 namespace llvm {
     25 
     26 class FoldingSetNodeID;
     27 class MDNode;
     28 class raw_ostream;
     29 
     30 /// MachinePointerInfo - This class contains a discriminated union of
     31 /// information about pointers in memory operands, relating them back to LLVM IR
     32 /// or to virtual locations (such as frame indices) that are exposed during
     33 /// codegen.
     34 struct MachinePointerInfo {
     35   /// V - This is the IR pointer value for the access, or it is null if unknown.
     36   /// If this is null, then the access is to a pointer in the default address
     37   /// space.
     38   PointerUnion<const Value *, const PseudoSourceValue *> V;
     39 
     40   /// Offset - This is an offset from the base Value*.
     41   int64_t Offset;
     42 
     43   explicit MachinePointerInfo(const Value *v = nullptr, int64_t offset = 0)
     44     : V(v), Offset(offset) {}
     45 
     46   explicit MachinePointerInfo(const PseudoSourceValue *v,
     47                               int64_t offset = 0)
     48     : V(v), Offset(offset) {}
     49 
     50   MachinePointerInfo getWithOffset(int64_t O) const {
     51     if (V.isNull()) return MachinePointerInfo();
     52     if (V.is<const Value*>())
     53       return MachinePointerInfo(V.get<const Value*>(), Offset+O);
     54     return MachinePointerInfo(V.get<const PseudoSourceValue*>(), Offset+O);
     55   }
     56 
     57   /// getAddrSpace - Return the LLVM IR address space number that this pointer
     58   /// points into.
     59   unsigned getAddrSpace() const;
     60 
     61   /// getConstantPool - Return a MachinePointerInfo record that refers to the
     62   /// constant pool.
     63   static MachinePointerInfo getConstantPool();
     64 
     65   /// getFixedStack - Return a MachinePointerInfo record that refers to the
     66   /// the specified FrameIndex.
     67   static MachinePointerInfo getFixedStack(int FI, int64_t offset = 0);
     68 
     69   /// getJumpTable - Return a MachinePointerInfo record that refers to a
     70   /// jump table entry.
     71   static MachinePointerInfo getJumpTable();
     72 
     73   /// getGOT - Return a MachinePointerInfo record that refers to a
     74   /// GOT entry.
     75   static MachinePointerInfo getGOT();
     76 
     77   /// getStack - stack pointer relative access.
     78   static MachinePointerInfo getStack(int64_t Offset);
     79 };
     80 
     81 
     82 //===----------------------------------------------------------------------===//
     83 /// MachineMemOperand - A description of a memory reference used in the backend.
     84 /// Instead of holding a StoreInst or LoadInst, this class holds the address
     85 /// Value of the reference along with a byte size and offset. This allows it
     86 /// to describe lowered loads and stores. Also, the special PseudoSourceValue
     87 /// objects can be used to represent loads and stores to memory locations
     88 /// that aren't explicit in the regular LLVM IR.
     89 ///
     90 class MachineMemOperand {
     91   MachinePointerInfo PtrInfo;
     92   uint64_t Size;
     93   unsigned Flags;
     94   const MDNode *TBAAInfo;
     95   const MDNode *Ranges;
     96 
     97 public:
     98   /// Flags values. These may be or'd together.
     99   enum MemOperandFlags {
    100     /// The memory access reads data.
    101     MOLoad = 1,
    102     /// The memory access writes data.
    103     MOStore = 2,
    104     /// The memory access is volatile.
    105     MOVolatile = 4,
    106     /// The memory access is non-temporal.
    107     MONonTemporal = 8,
    108     /// The memory access is invariant.
    109     MOInvariant = 16,
    110     // Target hints allow target passes to annotate memory operations.
    111     MOTargetStartBit = 5,
    112     MOTargetNumBits = 3,
    113     // This is the number of bits we need to represent flags.
    114     MOMaxBits = 8
    115   };
    116 
    117   /// MachineMemOperand - Construct an MachineMemOperand object with the
    118   /// specified PtrInfo, flags, size, and base alignment.
    119   MachineMemOperand(MachinePointerInfo PtrInfo, unsigned flags, uint64_t s,
    120                     unsigned base_alignment, const MDNode *TBAAInfo = nullptr,
    121                     const MDNode *Ranges = nullptr);
    122 
    123   const MachinePointerInfo &getPointerInfo() const { return PtrInfo; }
    124 
    125   /// getValue - Return the base address of the memory access. This may either
    126   /// be a normal LLVM IR Value, or one of the special values used in CodeGen.
    127   /// Special values are those obtained via
    128   /// PseudoSourceValue::getFixedStack(int), PseudoSourceValue::getStack, and
    129   /// other PseudoSourceValue member functions which return objects which stand
    130   /// for frame/stack pointer relative references and other special references
    131   /// which are not representable in the high-level IR.
    132   const Value *getValue() const { return PtrInfo.V.dyn_cast<const Value*>(); }
    133 
    134   const PseudoSourceValue *getPseudoValue() const {
    135     return PtrInfo.V.dyn_cast<const PseudoSourceValue*>();
    136   }
    137 
    138   const void *getOpaqueValue() const { return PtrInfo.V.getOpaqueValue(); }
    139 
    140   /// getFlags - Return the raw flags of the source value, \see MemOperandFlags.
    141   unsigned int getFlags() const { return Flags & ((1 << MOMaxBits) - 1); }
    142 
    143   /// Bitwise OR the current flags with the given flags.
    144   void setFlags(unsigned f) { Flags |= (f & ((1 << MOMaxBits) - 1)); }
    145 
    146   /// getOffset - For normal values, this is a byte offset added to the base
    147   /// address. For PseudoSourceValue::FPRel values, this is the FrameIndex
    148   /// number.
    149   int64_t getOffset() const { return PtrInfo.Offset; }
    150 
    151   unsigned getAddrSpace() const { return PtrInfo.getAddrSpace(); }
    152 
    153   /// getSize - Return the size in bytes of the memory reference.
    154   uint64_t getSize() const { return Size; }
    155 
    156   /// getAlignment - Return the minimum known alignment in bytes of the
    157   /// actual memory reference.
    158   uint64_t getAlignment() const;
    159 
    160   /// getBaseAlignment - Return the minimum known alignment in bytes of the
    161   /// base address, without the offset.
    162   uint64_t getBaseAlignment() const { return (1u << (Flags >> MOMaxBits)) >> 1; }
    163 
    164   /// getTBAAInfo - Return the TBAA tag for the memory reference.
    165   const MDNode *getTBAAInfo() const { return TBAAInfo; }
    166 
    167   /// getRanges - Return the range tag for the memory reference.
    168   const MDNode *getRanges() const { return Ranges; }
    169 
    170   bool isLoad() const { return Flags & MOLoad; }
    171   bool isStore() const { return Flags & MOStore; }
    172   bool isVolatile() const { return Flags & MOVolatile; }
    173   bool isNonTemporal() const { return Flags & MONonTemporal; }
    174   bool isInvariant() const { return Flags & MOInvariant; }
    175 
    176   /// isUnordered - Returns true if this memory operation doesn't have any
    177   /// ordering constraints other than normal aliasing. Volatile and atomic
    178   /// memory operations can't be reordered.
    179   ///
    180   /// Currently, we don't model the difference between volatile and atomic
    181   /// operations. They should retain their ordering relative to all memory
    182   /// operations.
    183   bool isUnordered() const { return !isVolatile(); }
    184 
    185   /// refineAlignment - Update this MachineMemOperand to reflect the alignment
    186   /// of MMO, if it has a greater alignment. This must only be used when the
    187   /// new alignment applies to all users of this MachineMemOperand.
    188   void refineAlignment(const MachineMemOperand *MMO);
    189 
    190   /// setValue - Change the SourceValue for this MachineMemOperand. This
    191   /// should only be used when an object is being relocated and all references
    192   /// to it are being updated.
    193   void setValue(const Value *NewSV) { PtrInfo.V = NewSV; }
    194   void setValue(const PseudoSourceValue *NewSV) { PtrInfo.V = NewSV; }
    195   void setOffset(int64_t NewOffset) { PtrInfo.Offset = NewOffset; }
    196 
    197   /// Profile - Gather unique data for the object.
    198   ///
    199   void Profile(FoldingSetNodeID &ID) const;
    200 };
    201 
    202 raw_ostream &operator<<(raw_ostream &OS, const MachineMemOperand &MRO);
    203 
    204 } // End llvm namespace
    205 
    206 #endif
    207