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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/BitmaskEnum.h"
     20 #include "llvm/ADT/PointerUnion.h"
     21 #include "llvm/CodeGen/PseudoSourceValue.h"
     22 #include "llvm/IR/Metadata.h"
     23 #include "llvm/IR/Value.h"  // PointerLikeTypeTraits<Value*>
     24 #include "llvm/Support/DataTypes.h"
     25 
     26 namespace llvm {
     27 
     28 class FoldingSetNodeID;
     29 class MDNode;
     30 class raw_ostream;
     31 class MachineFunction;
     32 class ModuleSlotTracker;
     33 
     34 /// This class contains a discriminated union of information about pointers in
     35 /// memory operands, relating them back to LLVM IR or to virtual locations (such
     36 /// as frame indices) that are exposed during codegen.
     37 struct MachinePointerInfo {
     38   /// This is the IR pointer value for the access, or it is null if unknown.
     39   /// If this is null, then the access is to a pointer in the default address
     40   /// space.
     41   PointerUnion<const Value *, const PseudoSourceValue *> V;
     42 
     43   /// Offset - This is an offset from the base Value*.
     44   int64_t Offset;
     45 
     46   explicit MachinePointerInfo(const Value *v = nullptr, int64_t offset = 0)
     47     : V(v), Offset(offset) {}
     48 
     49   explicit MachinePointerInfo(const PseudoSourceValue *v,
     50                               int64_t offset = 0)
     51     : V(v), Offset(offset) {}
     52 
     53   MachinePointerInfo getWithOffset(int64_t O) const {
     54     if (V.isNull()) return MachinePointerInfo();
     55     if (V.is<const Value*>())
     56       return MachinePointerInfo(V.get<const Value*>(), Offset+O);
     57     return MachinePointerInfo(V.get<const PseudoSourceValue*>(), Offset+O);
     58   }
     59 
     60   /// Return the LLVM IR address space number that this pointer points into.
     61   unsigned getAddrSpace() const;
     62 
     63   /// Return a MachinePointerInfo record that refers to the constant pool.
     64   static MachinePointerInfo getConstantPool(MachineFunction &MF);
     65 
     66   /// Return a MachinePointerInfo record that refers to the specified
     67   /// FrameIndex.
     68   static MachinePointerInfo getFixedStack(MachineFunction &MF, int FI,
     69                                           int64_t Offset = 0);
     70 
     71   /// Return a MachinePointerInfo record that refers to a jump table entry.
     72   static MachinePointerInfo getJumpTable(MachineFunction &MF);
     73 
     74   /// Return a MachinePointerInfo record that refers to a GOT entry.
     75   static MachinePointerInfo getGOT(MachineFunction &MF);
     76 
     77   /// Stack pointer relative access.
     78   static MachinePointerInfo getStack(MachineFunction &MF, int64_t Offset);
     79 };
     80 
     81 
     82 //===----------------------------------------------------------------------===//
     83 /// 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 public:
     92   /// Flags values. These may be or'd together.
     93   enum Flags : uint16_t {
     94     // No flags set.
     95     MONone = 0,
     96     /// The memory access reads data.
     97     MOLoad = 1u << 0,
     98     /// The memory access writes data.
     99     MOStore = 1u << 1,
    100     /// The memory access is volatile.
    101     MOVolatile = 1u << 2,
    102     /// The memory access is non-temporal.
    103     MONonTemporal = 1u << 3,
    104     /// The memory access is invariant.
    105     MOInvariant = 1u << 4,
    106 
    107     // Reserved for use by target-specific passes.
    108     MOTargetFlag1 = 1u << 5,
    109     MOTargetFlag2 = 1u << 6,
    110     MOTargetFlag3 = 1u << 7,
    111 
    112     LLVM_MARK_AS_BITMASK_ENUM(/* LargestFlag = */ MOTargetFlag3)
    113   };
    114 
    115 private:
    116   MachinePointerInfo PtrInfo;
    117   uint64_t Size;
    118   Flags FlagVals;
    119   uint16_t BaseAlignLog2; // log_2(base_alignment) + 1
    120   AAMDNodes AAInfo;
    121   const MDNode *Ranges;
    122 
    123 public:
    124   /// Construct a MachineMemOperand object with the specified PtrInfo, flags,
    125   /// size, and base alignment.
    126   MachineMemOperand(MachinePointerInfo PtrInfo, Flags flags, uint64_t s,
    127                     unsigned base_alignment,
    128                     const AAMDNodes &AAInfo = AAMDNodes(),
    129                     const MDNode *Ranges = nullptr);
    130 
    131   const MachinePointerInfo &getPointerInfo() const { return PtrInfo; }
    132 
    133   /// Return the base address of the memory access. This may either be a normal
    134   /// LLVM IR Value, or one of the special values used in CodeGen.
    135   /// Special values are those obtained via
    136   /// PseudoSourceValue::getFixedStack(int), PseudoSourceValue::getStack, and
    137   /// other PseudoSourceValue member functions which return objects which stand
    138   /// for frame/stack pointer relative references and other special references
    139   /// which are not representable in the high-level IR.
    140   const Value *getValue() const { return PtrInfo.V.dyn_cast<const Value*>(); }
    141 
    142   const PseudoSourceValue *getPseudoValue() const {
    143     return PtrInfo.V.dyn_cast<const PseudoSourceValue*>();
    144   }
    145 
    146   const void *getOpaqueValue() const { return PtrInfo.V.getOpaqueValue(); }
    147 
    148   /// Return the raw flags of the source value, \see Flags.
    149   Flags getFlags() const { return FlagVals; }
    150 
    151   /// Bitwise OR the current flags with the given flags.
    152   void setFlags(Flags f) { FlagVals |= f; }
    153 
    154   /// For normal values, this is a byte offset added to the base address.
    155   /// For PseudoSourceValue::FPRel values, this is the FrameIndex number.
    156   int64_t getOffset() const { return PtrInfo.Offset; }
    157 
    158   unsigned getAddrSpace() const { return PtrInfo.getAddrSpace(); }
    159 
    160   /// Return the size in bytes of the memory reference.
    161   uint64_t getSize() const { return Size; }
    162 
    163   /// Return the minimum known alignment in bytes of the actual memory
    164   /// reference.
    165   uint64_t getAlignment() const;
    166 
    167   /// Return the minimum known alignment in bytes of the base address, without
    168   /// the offset.
    169   uint64_t getBaseAlignment() const { return (1u << BaseAlignLog2) >> 1; }
    170 
    171   /// Return the AA tags for the memory reference.
    172   AAMDNodes getAAInfo() const { return AAInfo; }
    173 
    174   /// Return the range tag for the memory reference.
    175   const MDNode *getRanges() const { return Ranges; }
    176 
    177   bool isLoad() const { return FlagVals & MOLoad; }
    178   bool isStore() const { return FlagVals & MOStore; }
    179   bool isVolatile() const { return FlagVals & MOVolatile; }
    180   bool isNonTemporal() const { return FlagVals & MONonTemporal; }
    181   bool isInvariant() const { return FlagVals & MOInvariant; }
    182 
    183   /// Returns true if this memory operation doesn't have any ordering
    184   /// constraints other than normal aliasing. Volatile and atomic memory
    185   /// operations can't be reordered.
    186   ///
    187   /// Currently, we don't model the difference between volatile and atomic
    188   /// operations. They should retain their ordering relative to all memory
    189   /// operations.
    190   bool isUnordered() const { return !isVolatile(); }
    191 
    192   /// Update this MachineMemOperand to reflect the alignment of MMO, if it has a
    193   /// greater alignment. This must only be used when the new alignment applies
    194   /// to all users of this MachineMemOperand.
    195   void refineAlignment(const MachineMemOperand *MMO);
    196 
    197   /// Change the SourceValue for this MachineMemOperand. This should only be
    198   /// used when an object is being relocated and all references to it are being
    199   /// updated.
    200   void setValue(const Value *NewSV) { PtrInfo.V = NewSV; }
    201   void setValue(const PseudoSourceValue *NewSV) { PtrInfo.V = NewSV; }
    202   void setOffset(int64_t NewOffset) { PtrInfo.Offset = NewOffset; }
    203 
    204   /// Profile - Gather unique data for the object.
    205   ///
    206   void Profile(FoldingSetNodeID &ID) const;
    207 
    208   /// Support for operator<<.
    209   /// @{
    210   void print(raw_ostream &OS) const;
    211   void print(raw_ostream &OS, ModuleSlotTracker &MST) const;
    212   /// @}
    213 
    214   friend bool operator==(const MachineMemOperand &LHS,
    215                          const MachineMemOperand &RHS) {
    216     return LHS.getValue() == RHS.getValue() &&
    217            LHS.getPseudoValue() == RHS.getPseudoValue() &&
    218            LHS.getSize() == RHS.getSize() &&
    219            LHS.getOffset() == RHS.getOffset() &&
    220            LHS.getFlags() == RHS.getFlags() &&
    221            LHS.getAAInfo() == RHS.getAAInfo() &&
    222            LHS.getRanges() == RHS.getRanges() &&
    223            LHS.getAlignment() == RHS.getAlignment() &&
    224            LHS.getAddrSpace() == RHS.getAddrSpace();
    225   }
    226 
    227   friend bool operator!=(const MachineMemOperand &LHS,
    228                          const MachineMemOperand &RHS) {
    229     return !(LHS == RHS);
    230   }
    231 };
    232 
    233 inline raw_ostream &operator<<(raw_ostream &OS, const MachineMemOperand &MRO) {
    234   MRO.print(OS);
    235   return OS;
    236 }
    237 
    238 } // End llvm namespace
    239 
    240 #endif
    241