1 //===- llvm/Support/Memory.h - Memory Support -------------------*- 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 declares the llvm::sys::Memory class.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #ifndef LLVM_SUPPORT_MEMORY_H
15 #define LLVM_SUPPORT_MEMORY_H
16
17 #include "llvm/Support/DataTypes.h"
18 #include <string>
19 #include <system_error>
20
21 namespace llvm {
22 namespace sys {
23
24 /// This class encapsulates the notion of a memory block which has an address
25 /// and a size. It is used by the Memory class (a friend) as the result of
26 /// various memory allocation operations.
27 /// @see Memory
28 /// Memory block abstraction.
29 class MemoryBlock {
30 public:
31 MemoryBlock() : Address(nullptr), Size(0) { }
32 MemoryBlock(void *addr, size_t size) : Address(addr), Size(size) { }
33 void *base() const { return Address; }
34 size_t size() const { return Size; }
35
36 private:
37 void *Address; ///< Address of first byte of memory area
38 size_t Size; ///< Size, in bytes of the memory area
39 friend class Memory;
40 };
41
42 /// This class provides various memory handling functions that manipulate
43 /// MemoryBlock instances.
44 /// @since 1.4
45 /// An abstraction for memory operations.
46 class Memory {
47 public:
48 enum ProtectionFlags {
49 MF_READ = 0x1000000,
50 MF_WRITE = 0x2000000,
51 MF_EXEC = 0x4000000
52 };
53
54 /// This method allocates a block of memory that is suitable for loading
55 /// dynamically generated code (e.g. JIT). An attempt to allocate
56 /// \p NumBytes bytes of virtual memory is made.
57 /// \p NearBlock may point to an existing allocation in which case
58 /// an attempt is made to allocate more memory near the existing block.
59 /// The actual allocated address is not guaranteed to be near the requested
60 /// address.
61 /// \p Flags is used to set the initial protection flags for the block
62 /// of the memory.
63 /// \p EC [out] returns an object describing any error that occurs.
64 ///
65 /// This method may allocate more than the number of bytes requested. The
66 /// actual number of bytes allocated is indicated in the returned
67 /// MemoryBlock.
68 ///
69 /// The start of the allocated block must be aligned with the
70 /// system allocation granularity (64K on Windows, page size on Linux).
71 /// If the address following \p NearBlock is not so aligned, it will be
72 /// rounded up to the next allocation granularity boundary.
73 ///
74 /// \r a non-null MemoryBlock if the function was successful,
75 /// otherwise a null MemoryBlock is with \p EC describing the error.
76 ///
77 /// Allocate mapped memory.
78 static MemoryBlock allocateMappedMemory(size_t NumBytes,
79 const MemoryBlock *const NearBlock,
80 unsigned Flags,
81 std::error_code &EC);
82
83 /// This method releases a block of memory that was allocated with the
84 /// allocateMappedMemory method. It should not be used to release any
85 /// memory block allocated any other way.
86 /// \p Block describes the memory to be released.
87 ///
88 /// \r error_success if the function was successful, or an error_code
89 /// describing the failure if an error occurred.
90 ///
91 /// Release mapped memory.
92 static std::error_code releaseMappedMemory(MemoryBlock &Block);
93
94 /// This method sets the protection flags for a block of memory to the
95 /// state specified by /p Flags. The behavior is not specified if the
96 /// memory was not allocated using the allocateMappedMemory method.
97 /// \p Block describes the memory block to be protected.
98 /// \p Flags specifies the new protection state to be assigned to the block.
99 /// \p ErrMsg [out] returns a string describing any error that occurred.
100 ///
101 /// If \p Flags is MF_WRITE, the actual behavior varies
102 /// with the operating system (i.e. MF_READ | MF_WRITE on Windows) and the
103 /// target architecture (i.e. MF_WRITE -> MF_READ | MF_WRITE on i386).
104 ///
105 /// \r error_success if the function was successful, or an error_code
RuntimeFunction(const support::ulittle32_t * Data)106 /// describing the failure if an error occurred.
107 ///
108 /// Set memory protection state.
109 static std::error_code protectMappedMemory(const MemoryBlock &Block,
110 unsigned Flags);
111
112 /// InvalidateInstructionCache - Before the JIT can run a block of code
Flag()113 /// that has been emitted it must invalidate the instruction cache on some
114 /// platforms.
115 static void InvalidateInstructionCache(const void *Addr, size_t Len);
116 };
ExceptionInformationRVA()117
118 /// Owning version of MemoryBlock.
119 class OwningMemoryBlock {
120 public:
121 OwningMemoryBlock() = default;
122 explicit OwningMemoryBlock(MemoryBlock M) : M(M) {}
123 OwningMemoryBlock(OwningMemoryBlock &&Other) {
124 M = Other.M;
125 Other.M = MemoryBlock();
126 }
127 OwningMemoryBlock& operator=(OwningMemoryBlock &&Other) {
128 M = Other.M;
129 Other.M = MemoryBlock();
130 return *this;
131 }
132 ~OwningMemoryBlock() {
133 Memory::releaseMappedMemory(M);
134 }
135 void *base() const { return M.base(); }
136 size_t size() const { return M.size(); }
137 MemoryBlock getMemoryBlock() const { return M; }
138 private:
139 MemoryBlock M;
140 };
141
H()142 }
143 }
144
145 #endif
146