1 //===- llvm/System/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
22 /// This class encapsulates the notion of a memory block which has an address
23 /// and a size. It is used by the Memory class (a friend) as the result of
24 /// various memory allocation operations.
26 /// @brief Memory block abstraction.
29 void *base() const { return Address; }
30 unsigned size() const { return Size; }
32 void *Address; ///< Address of first byte of memory area
33 unsigned Size; ///< Size, in bytes of the memory area
37 /// This class provides various memory handling functions that manipulate
38 /// MemoryBlock instances.
40 /// @brief An abstraction for memory operations.
43 /// This method allocates a block of Read/Write/Execute memory that is
44 /// suitable for executing dynamically generated code (e.g. JIT). An
45 /// attempt to allocate \p NumBytes bytes of virtual memory is made.
46 /// \p NearBlock may point to an existing allocation in which case
47 /// an attempt is made to allocate more memory near the existing block.
49 /// On success, this returns a non-null memory block, otherwise it returns
50 /// a null memory block and fills in *ErrMsg.
52 /// @brief Allocate Read/Write/Execute memory.
53 static MemoryBlock AllocateRWX(unsigned NumBytes,
54 const MemoryBlock *NearBlock,
55 std::string *ErrMsg = 0);
57 /// This method releases a block of Read/Write/Execute memory that was
58 /// allocated with the AllocateRWX method. It should not be used to
59 /// release any memory block allocated any other way.
61 /// On success, this returns false, otherwise it returns true and fills
63 /// @throws std::string if an error occurred.
64 /// @brief Release Read/Write/Execute memory.
65 static bool ReleaseRWX(MemoryBlock &block, std::string *ErrMsg = 0);
68 /// InvalidateInstructionCache - Before the JIT can run a block of code
69 /// that has been emitted it must invalidate the instruction cache on some
71 static void InvalidateInstructionCache(const void *Addr, size_t Len);
73 /// setExecutable - Before the JIT can run a block of code, it has to be
74 /// given read and executable privilege. Return true if it is already r-x
75 /// or the system is able to change its previlege.
76 static bool setExecutable (MemoryBlock &M, std::string *ErrMsg = 0);
78 /// setWritable - When adding to a block of code, the JIT may need
79 /// to mark a block of code as RW since the protections are on page
80 /// boundaries, and the JIT internal allocations are not page aligned.
81 static bool setWritable (MemoryBlock &M, std::string *ErrMsg = 0);
83 /// setRangeExecutable - Mark the page containing a range of addresses
85 static bool setRangeExecutable(const void *Addr, size_t Size);
87 /// setRangeWritable - Mark the page containing a range of addresses
89 static bool setRangeWritable(const void *Addr, size_t Size);