include/llvm/CodeGen/MachineMemOperand.h

   1 //==- llvm/CodeGen/MachineMemOperand.h - MachineMemOperand class -*- C++ -*-==//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file contains the declaration of the MachineMemOperand class, which is a
  10 // description of a memory reference. It is used to help track dependencies
  11 // in the backend.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_CODEGEN_MACHINEMEMOPERAND_H
  16 #define LLVM_CODEGEN_MACHINEMEMOPERAND_H
  17
  18 #include "llvm/ADT/BitmaskEnum.h"
  19 #include "llvm/ADT/PointerUnion.h"
  20 #include "llvm/CodeGen/PseudoSourceValue.h"
  21 #include "llvm/IR/Value.h" // PointerLikeTypeTraits<Value*>
  22 #include "llvm/Support/AtomicOrdering.h"
  23 #include "llvm/Support/DataTypes.h"
  24
  25 namespace llvm {
  26
  27 class FoldingSetNodeID;
  28 class MDNode;
  29 class raw_ostream;
  30 class MachineFunction;
  31 class ModuleSlotTracker;
  32
  33 /// This class contains a discriminated union of information about pointers in
  34 /// memory operands, relating them back to LLVM IR or to virtual locations (such
  35 /// as frame indices) that are exposed during codegen.
  36 struct MachinePointerInfo {
  37   /// This is the IR pointer value for the access, or it is null if unknown.
  38   /// If this is null, then the access is to a pointer in the default address
  39   /// space.
  40   PointerUnion<const Value *, const PseudoSourceValue *> V;
  41
  42   /// Offset - This is an offset from the base Value*.
  43   int64_t Offset;
  44
  45   uint8_t StackID;
  46
  47   unsigned AddrSpace = 0;
  48
  49   explicit MachinePointerInfo(const Value *v, int64_t offset = 0,
  50                               uint8_t ID = 0)
  51       : V(v), Offset(offset), StackID(ID) {
  52     AddrSpace = v ? v->getType()->getPointerAddressSpace() : 0;
  53   }
  54
  55   explicit MachinePointerInfo(const PseudoSourceValue *v, int64_t offset = 0,
  56                               uint8_t ID = 0)
  57       : V(v), Offset(offset), StackID(ID) {
  58     AddrSpace = v ? v->getAddressSpace() : 0;
  59   }
  60
  61   explicit MachinePointerInfo(unsigned AddressSpace = 0)
  62       : V((const Value *)nullptr), Offset(0), StackID(0),
  63         AddrSpace(AddressSpace) {}
  64
  65   explicit MachinePointerInfo(
  66     PointerUnion<const Value *, const PseudoSourceValue *> v,
  67     int64_t offset = 0,
  68     uint8_t ID = 0)
  69     : V(v), Offset(offset), StackID(ID) {
  70     if (V) {
  71       if (const auto *ValPtr = V.dyn_cast<const Value*>())
  72         AddrSpace = ValPtr->getType()->getPointerAddressSpace();
  73       else
  74         AddrSpace = V.get<const PseudoSourceValue*>()->getAddressSpace();
  75     }
  76   }
  77
  78   MachinePointerInfo getWithOffset(int64_t O) const {
  79     if (V.isNull())
  80       return MachinePointerInfo(AddrSpace);
  81     if (V.is<const Value*>())
  82       return MachinePointerInfo(V.get<const Value*>(), Offset+O, StackID);
  83     return MachinePointerInfo(V.get<const PseudoSourceValue*>(), Offset+O,
  84                               StackID);
  85   }
  86
  87   /// Return true if memory region [V, V+Offset+Size) is known to be
  88   /// dereferenceable.
  89   bool isDereferenceable(unsigned Size, LLVMContext &C,
  90                          const DataLayout &DL) const;
  91
  92   /// Return the LLVM IR address space number that this pointer points into.
  93   unsigned getAddrSpace() const;
  94
  95   /// Return a MachinePointerInfo record that refers to the constant pool.
  96   static MachinePointerInfo getConstantPool(MachineFunction &MF);
  97
  98   /// Return a MachinePointerInfo record that refers to the specified
  99   /// FrameIndex.
 100   static MachinePointerInfo getFixedStack(MachineFunction &MF, int FI,
 101                                           int64_t Offset = 0);
 102
 103   /// Return a MachinePointerInfo record that refers to a jump table entry.
 104   static MachinePointerInfo getJumpTable(MachineFunction &MF);
 105
 106   /// Return a MachinePointerInfo record that refers to a GOT entry.
 107   static MachinePointerInfo getGOT(MachineFunction &MF);
 108
 109   /// Stack pointer relative access.
 110   static MachinePointerInfo getStack(MachineFunction &MF, int64_t Offset,
 111                                      uint8_t ID = 0);
 112
 113   /// Stack memory without other information.
 114   static MachinePointerInfo getUnknownStack(MachineFunction &MF);
 115 };
 116
 117
 118 //===----------------------------------------------------------------------===//
 119 /// A description of a memory reference used in the backend.
 120 /// Instead of holding a StoreInst or LoadInst, this class holds the address
 121 /// Value of the reference along with a byte size and offset. This allows it
 122 /// to describe lowered loads and stores. Also, the special PseudoSourceValue
 123 /// objects can be used to represent loads and stores to memory locations
 124 /// that aren't explicit in the regular LLVM IR.
 125 ///
 126 class MachineMemOperand {
 127 public:
 128   /// Flags values. These may be or'd together.
 129   enum Flags : uint16_t {
 130     // No flags set.
 131     MONone = 0,
 132     /// The memory access reads data.
 133     MOLoad = 1u << 0,
 134     /// The memory access writes data.
 135     MOStore = 1u << 1,
 136     /// The memory access is volatile.
 137     MOVolatile = 1u << 2,
 138     /// The memory access is non-temporal.
 139     MONonTemporal = 1u << 3,
 140     /// The memory access is dereferenceable (i.e., doesn't trap).
 141     MODereferenceable = 1u << 4,
 142     /// The memory access always returns the same value (or traps).
 143     MOInvariant = 1u << 5,
 144
 145     // Reserved for use by target-specific passes.
 146     // Targets may override getSerializableMachineMemOperandTargetFlags() to
 147     // enable MIR serialization/parsing of these flags.  If more of these flags
 148     // are added, the MIR printing/parsing code will need to be updated as well.
 149     MOTargetFlag1 = 1u << 6,
 150     MOTargetFlag2 = 1u << 7,
 151     MOTargetFlag3 = 1u << 8,
 152
 153     LLVM_MARK_AS_BITMASK_ENUM(/* LargestFlag = */ MOTargetFlag3)
 154   };
 155
 156 private:
 157   /// Atomic information for this memory operation.
 158   struct MachineAtomicInfo {
 159     /// Synchronization scope ID for this memory operation.
 160     unsigned SSID : 8;            // SyncScope::ID
 161     /// Atomic ordering requirements for this memory operation. For cmpxchg
 162     /// atomic operations, atomic ordering requirements when store occurs.
 163     unsigned Ordering : 4;        // enum AtomicOrdering
 164     /// For cmpxchg atomic operations, atomic ordering requirements when store
 165     /// does not occur.
 166     unsigned FailureOrdering : 4; // enum AtomicOrdering
 167   };
 168
 169   MachinePointerInfo PtrInfo;
 170   uint64_t Size;
 171   Flags FlagVals;
 172   uint16_t BaseAlignLog2; // log_2(base_alignment) + 1
 173   MachineAtomicInfo AtomicInfo;
 174   AAMDNodes AAInfo;
 175   const MDNode *Ranges;
 176
 177 public:
 178   /// Construct a MachineMemOperand object with the specified PtrInfo, flags,
 179   /// size, and base alignment. For atomic operations the synchronization scope
 180   /// and atomic ordering requirements must also be specified. For cmpxchg
 181   /// atomic operations the atomic ordering requirements when store does not
 182   /// occur must also be specified.
 183   MachineMemOperand(MachinePointerInfo PtrInfo, Flags flags, uint64_t s,
 184                     uint64_t a,
 185                     const AAMDNodes &AAInfo = AAMDNodes(),
 186                     const MDNode *Ranges = nullptr,
 187                     SyncScope::ID SSID = SyncScope::System,
 188                     AtomicOrdering Ordering = AtomicOrdering::NotAtomic,
 189                     AtomicOrdering FailureOrdering = AtomicOrdering::NotAtomic);
 190
 191   const MachinePointerInfo &getPointerInfo() const { return PtrInfo; }
 192
 193   /// Return the base address of the memory access. This may either be a normal
 194   /// LLVM IR Value, or one of the special values used in CodeGen.
 195   /// Special values are those obtained via
 196   /// PseudoSourceValue::getFixedStack(int), PseudoSourceValue::getStack, and
 197   /// other PseudoSourceValue member functions which return objects which stand
 198   /// for frame/stack pointer relative references and other special references
 199   /// which are not representable in the high-level IR.
 200   const Value *getValue() const { return PtrInfo.V.dyn_cast<const Value*>(); }
 201
 202   const PseudoSourceValue *getPseudoValue() const {
 203     return PtrInfo.V.dyn_cast<const PseudoSourceValue*>();
 204   }
 205
 206   const void *getOpaqueValue() const { return PtrInfo.V.getOpaqueValue(); }
 207
 208   /// Return the raw flags of the source value, \see Flags.
 209   Flags getFlags() const { return FlagVals; }
 210
 211   /// Bitwise OR the current flags with the given flags.
 212   void setFlags(Flags f) { FlagVals |= f; }
 213
 214   /// For normal values, this is a byte offset added to the base address.
 215   /// For PseudoSourceValue::FPRel values, this is the FrameIndex number.
 216   int64_t getOffset() const { return PtrInfo.Offset; }
 217
 218   unsigned getAddrSpace() const { return PtrInfo.getAddrSpace(); }
 219
 220   /// Return the size in bytes of the memory reference.
 221   uint64_t getSize() const { return Size; }
 222
 223   /// Return the size in bits of the memory reference.
 224   uint64_t getSizeInBits() const { return Size * 8; }
 225
 226   /// Return the minimum known alignment in bytes of the actual memory
 227   /// reference.
 228   uint64_t getAlignment() const;
 229
 230   /// Return the minimum known alignment in bytes of the base address, without
 231   /// the offset.
 232   uint64_t getBaseAlignment() const { return (1u << BaseAlignLog2) >> 1; }
 233
 234   /// Return the AA tags for the memory reference.
 235   AAMDNodes getAAInfo() const { return AAInfo; }
 236
 237   /// Return the range tag for the memory reference.
 238   const MDNode *getRanges() const { return Ranges; }
 239
 240   /// Returns the synchronization scope ID for this memory operation.
 241   SyncScope::ID getSyncScopeID() const {
 242     return static_cast<SyncScope::ID>(AtomicInfo.SSID);
 243   }
 244
 245   /// Return the atomic ordering requirements for this memory operation. For
 246   /// cmpxchg atomic operations, return the atomic ordering requirements when
 247   /// store occurs.
 248   AtomicOrdering getOrdering() const {
 249     return static_cast<AtomicOrdering>(AtomicInfo.Ordering);
 250   }
 251
 252   /// For cmpxchg atomic operations, return the atomic ordering requirements
 253   /// when store does not occur.
 254   AtomicOrdering getFailureOrdering() const {
 255     return static_cast<AtomicOrdering>(AtomicInfo.FailureOrdering);
 256   }
 257
 258   bool isLoad() const { return FlagVals & MOLoad; }
 259   bool isStore() const { return FlagVals & MOStore; }
 260   bool isVolatile() const { return FlagVals & MOVolatile; }
 261   bool isNonTemporal() const { return FlagVals & MONonTemporal; }
 262   bool isDereferenceable() const { return FlagVals & MODereferenceable; }
 263   bool isInvariant() const { return FlagVals & MOInvariant; }
 264
 265   /// Returns true if this operation has an atomic ordering requirement of
 266   /// unordered or higher, false otherwise.
 267   bool isAtomic() const { return getOrdering() != AtomicOrdering::NotAtomic; }
 268
 269   /// Returns true if this memory operation doesn't have any ordering
 270   /// constraints other than normal aliasing. Volatile and (ordered) atomic
 271   /// memory operations can't be reordered.
 272   bool isUnordered() const {
 273     return (getOrdering() == AtomicOrdering::NotAtomic ||
 274             getOrdering() == AtomicOrdering::Unordered) &&
 275            !isVolatile();
 276   }
 277
 278   /// Update this MachineMemOperand to reflect the alignment of MMO, if it has a
 279   /// greater alignment. This must only be used when the new alignment applies
 280   /// to all users of this MachineMemOperand.
 281   void refineAlignment(const MachineMemOperand *MMO);
 282
 283   /// Change the SourceValue for this MachineMemOperand. This should only be
 284   /// used when an object is being relocated and all references to it are being
 285   /// updated.
 286   void setValue(const Value *NewSV) { PtrInfo.V = NewSV; }
 287   void setValue(const PseudoSourceValue *NewSV) { PtrInfo.V = NewSV; }
 288   void setOffset(int64_t NewOffset) { PtrInfo.Offset = NewOffset; }
 289
 290   /// Profile - Gather unique data for the object.
 291   ///
 292   void Profile(FoldingSetNodeID &ID) const;
 293
 294   /// Support for operator<<.
 295   /// @{
 296   void print(raw_ostream &OS, ModuleSlotTracker &MST,
 297              SmallVectorImpl<StringRef> &SSNs, const LLVMContext &Context,
 298              const MachineFrameInfo *MFI, const TargetInstrInfo *TII) const;
 299   /// @}
 300
 301   friend bool operator==(const MachineMemOperand &LHS,
 302                          const MachineMemOperand &RHS) {
 303     return LHS.getValue() == RHS.getValue() &&
 304            LHS.getPseudoValue() == RHS.getPseudoValue() &&
 305            LHS.getSize() == RHS.getSize() &&
 306            LHS.getOffset() == RHS.getOffset() &&
 307            LHS.getFlags() == RHS.getFlags() &&
 308            LHS.getAAInfo() == RHS.getAAInfo() &&
 309            LHS.getRanges() == RHS.getRanges() &&
 310            LHS.getAlignment() == RHS.getAlignment() &&
 311            LHS.getAddrSpace() == RHS.getAddrSpace();
 312   }
 313
 314   friend bool operator!=(const MachineMemOperand &LHS,
 315                          const MachineMemOperand &RHS) {
 316     return !(LHS == RHS);
 317   }
 318 };
 319
 320 } // End llvm namespace
 321
 322 #endif