1 //===- llvm/Support/Memory.h - Memory Support --------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file declares the llvm::sys::Memory class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_SYSTEM_MEMORY_H
15 #define LLVM_SYSTEM_MEMORY_H
17 #include "llvm/Support/DataTypes.h"
23 /// This class encapsulates the notion of a memory block which has an address
24 /// and a size. It is used by the Memory class (a friend) as the result of
25 /// various memory allocation operations.
27 /// @brief Memory block abstraction.
30 MemoryBlock() : Address(0), Size(0) { }
31 MemoryBlock(void *addr, size_t size) : Address(addr), Size(size) { }
32 void *base() const { return Address; }
33 size_t size() const { return Size; }
35 void *Address; ///< Address of first byte of memory area
36 size_t Size; ///< Size, in bytes of the memory area
40 /// This class provides various memory handling functions that manipulate
41 /// MemoryBlock instances.
43 /// @brief An abstraction for memory operations.
46 /// This method allocates a block of Read/Write/Execute memory that is
47 /// suitable for executing dynamically generated code (e.g. JIT). An
48 /// attempt to allocate \p NumBytes bytes of virtual memory is made.
49 /// \p NearBlock may point to an existing allocation in which case
50 /// an attempt is made to allocate more memory near the existing block.
52 /// On success, this returns a non-null memory block, otherwise it returns
53 /// a null memory block and fills in *ErrMsg.
55 /// @brief Allocate Read/Write/Execute memory.
56 static MemoryBlock AllocateRWX(size_t NumBytes,
57 const MemoryBlock *NearBlock,
58 std::string *ErrMsg = 0);
60 /// This method releases a block of Read/Write/Execute memory that was
61 /// allocated with the AllocateRWX method. It should not be used to
62 /// release any memory block allocated any other way.
64 /// On success, this returns false, otherwise it returns true and fills
66 /// @brief Release Read/Write/Execute memory.
67 static bool ReleaseRWX(MemoryBlock &block, std::string *ErrMsg = 0);
70 /// InvalidateInstructionCache - Before the JIT can run a block of code
71 /// that has been emitted it must invalidate the instruction cache on some
73 static void InvalidateInstructionCache(const void *Addr, size_t Len);
75 /// setExecutable - Before the JIT can run a block of code, it has to be
76 /// given read and executable privilege. Return true if it is already r-x
77 /// or the system is able to change its previlege.
78 static bool setExecutable(MemoryBlock &M, std::string *ErrMsg = 0);
80 /// setWritable - When adding to a block of code, the JIT may need
81 /// to mark a block of code as RW since the protections are on page
82 /// boundaries, and the JIT internal allocations are not page aligned.
83 static bool setWritable(MemoryBlock &M, std::string *ErrMsg = 0);
85 /// setRangeExecutable - Mark the page containing a range of addresses
87 static bool setRangeExecutable(const void *Addr, size_t Size);
89 /// setRangeWritable - Mark the page containing a range of addresses
91 static bool setRangeWritable(const void *Addr, size_t Size);