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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 raw_ostream;
26 
27 /// MachinePointerInfo - This class contains a discriminated union of
28 /// information about pointers in memory operands, relating them back to LLVM IR
29 /// or to virtual locations (such as frame indices) that are exposed during
30 /// codegen.
31 struct MachinePointerInfo {
32   /// V - This is the IR pointer value for the access, or it is null if unknown.
33   /// If this is null, then the access is to a pointer in the default address
34   /// space.
35   const Value *V;
36 
37   /// Offset - This is an offset from the base Value*.
38   int64_t Offset;
39 
40   explicit MachinePointerInfo(const Value *v = 0, int64_t offset = 0)
VMachinePointerInfo41     : V(v), Offset(offset) {}
42 
getWithOffsetMachinePointerInfo43   MachinePointerInfo getWithOffset(int64_t O) const {
44     if (V == 0) return MachinePointerInfo(0, 0);
45     return MachinePointerInfo(V, Offset+O);
46   }
47 
48   /// getAddrSpace - Return the LLVM IR address space number that this pointer
49   /// points into.
50   unsigned getAddrSpace() const;
51 
52   /// getConstantPool - Return a MachinePointerInfo record that refers to the
53   /// constant pool.
54   static MachinePointerInfo getConstantPool();
55 
56   /// getFixedStack - Return a MachinePointerInfo record that refers to the
57   /// the specified FrameIndex.
58   static MachinePointerInfo getFixedStack(int FI, int64_t offset = 0);
59 
60   /// getJumpTable - Return a MachinePointerInfo record that refers to a
61   /// jump table entry.
62   static MachinePointerInfo getJumpTable();
63 
64   /// getGOT - Return a MachinePointerInfo record that refers to a
65   /// GOT entry.
66   static MachinePointerInfo getGOT();
67 
68   /// getStack - stack pointer relative access.
69   static MachinePointerInfo getStack(int64_t Offset);
70 };
71 
72 
73 //===----------------------------------------------------------------------===//
74 /// MachineMemOperand - A description of a memory reference used in the backend.
75 /// Instead of holding a StoreInst or LoadInst, this class holds the address
76 /// Value of the reference along with a byte size and offset. This allows it
77 /// to describe lowered loads and stores. Also, the special PseudoSourceValue
78 /// objects can be used to represent loads and stores to memory locations
79 /// that aren't explicit in the regular LLVM IR.
80 ///
81 class MachineMemOperand {
82   MachinePointerInfo PtrInfo;
83   uint64_t Size;
84   unsigned Flags;
85   const MDNode *TBAAInfo;
86 
87 public:
88   /// Flags values. These may be or'd together.
89   enum MemOperandFlags {
90     /// The memory access reads data.
91     MOLoad = 1,
92     /// The memory access writes data.
93     MOStore = 2,
94     /// The memory access is volatile.
95     MOVolatile = 4,
96     /// The memory access is non-temporal.
97     MONonTemporal = 8,
98     // This is the number of bits we need to represent flags.
99     MOMaxBits = 4
100   };
101 
102   /// MachineMemOperand - Construct an MachineMemOperand object with the
103   /// specified PtrInfo, flags, size, and base alignment.
104   MachineMemOperand(MachinePointerInfo PtrInfo, unsigned flags, uint64_t s,
105                     unsigned base_alignment, const MDNode *TBAAInfo = 0);
106 
getPointerInfo()107   const MachinePointerInfo &getPointerInfo() const { return PtrInfo; }
108 
109   /// getValue - Return the base address of the memory access. This may either
110   /// be a normal LLVM IR Value, or one of the special values used in CodeGen.
111   /// Special values are those obtained via
112   /// PseudoSourceValue::getFixedStack(int), PseudoSourceValue::getStack, and
113   /// other PseudoSourceValue member functions which return objects which stand
114   /// for frame/stack pointer relative references and other special references
115   /// which are not representable in the high-level IR.
getValue()116   const Value *getValue() const { return PtrInfo.V; }
117 
118   /// getFlags - Return the raw flags of the source value, \see MemOperandFlags.
getFlags()119   unsigned int getFlags() const { return Flags & ((1 << MOMaxBits) - 1); }
120 
121   /// getOffset - For normal values, this is a byte offset added to the base
122   /// address. For PseudoSourceValue::FPRel values, this is the FrameIndex
123   /// number.
getOffset()124   int64_t getOffset() const { return PtrInfo.Offset; }
125 
126   /// getSize - Return the size in bytes of the memory reference.
getSize()127   uint64_t getSize() const { return Size; }
128 
129   /// getAlignment - Return the minimum known alignment in bytes of the
130   /// actual memory reference.
131   uint64_t getAlignment() const;
132 
133   /// getBaseAlignment - Return the minimum known alignment in bytes of the
134   /// base address, without the offset.
getBaseAlignment()135   uint64_t getBaseAlignment() const { return (1u << (Flags >> MOMaxBits)) >> 1; }
136 
137   /// getTBAAInfo - Return the TBAA tag for the memory reference.
getTBAAInfo()138   const MDNode *getTBAAInfo() const { return TBAAInfo; }
139 
isLoad()140   bool isLoad() const { return Flags & MOLoad; }
isStore()141   bool isStore() const { return Flags & MOStore; }
isVolatile()142   bool isVolatile() const { return Flags & MOVolatile; }
isNonTemporal()143   bool isNonTemporal() const { return Flags & MONonTemporal; }
144 
145   /// refineAlignment - Update this MachineMemOperand to reflect the alignment
146   /// of MMO, if it has a greater alignment. This must only be used when the
147   /// new alignment applies to all users of this MachineMemOperand.
148   void refineAlignment(const MachineMemOperand *MMO);
149 
150   /// setValue - Change the SourceValue for this MachineMemOperand. This
151   /// should only be used when an object is being relocated and all references
152   /// to it are being updated.
setValue(const Value * NewSV)153   void setValue(const Value *NewSV) { PtrInfo.V = NewSV; }
setOffset(int64_t NewOffset)154   void setOffset(int64_t NewOffset) { PtrInfo.Offset = NewOffset; }
155 
156   /// Profile - Gather unique data for the object.
157   ///
158   void Profile(FoldingSetNodeID &ID) const;
159 };
160 
161 raw_ostream &operator<<(raw_ostream &OS, const MachineMemOperand &MRO);
162 
163 } // End llvm namespace
164 
165 #endif
166