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