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_SYSTEM_MEMORY_H 15 #define LLVM_SYSTEM_MEMORY_H 16 17 #include "llvm/Support/DataTypes.h" 18 #include <string> 19 20 namespace llvm { 21 namespace sys { 22 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. 26 /// @see Memory 27 /// @brief Memory block abstraction. 28 class MemoryBlock { 29 public: 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; } 34 private: 35 void *Address; ///< Address of first byte of memory area 36 size_t Size; ///< Size, in bytes of the memory area 37 friend class Memory; 38 }; 39 40 /// This class provides various memory handling functions that manipulate 41 /// MemoryBlock instances. 42 /// @since 1.4 43 /// @brief An abstraction for memory operations. 44 class Memory { 45 public: 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. 51 /// 52 /// On success, this returns a non-null memory block, otherwise it returns 53 /// a null memory block and fills in *ErrMsg. 54 /// 55 /// @brief Allocate Read/Write/Execute memory. 56 static MemoryBlock AllocateRWX(size_t NumBytes, 57 const MemoryBlock *NearBlock, 58 std::string *ErrMsg = 0); 59 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. 63 /// 64 /// On success, this returns false, otherwise it returns true and fills 65 /// in *ErrMsg. 66 /// @brief Release Read/Write/Execute memory. 67 static bool ReleaseRWX(MemoryBlock &block, std::string *ErrMsg = 0); 68 69 70 /// InvalidateInstructionCache - Before the JIT can run a block of code 71 /// that has been emitted it must invalidate the instruction cache on some 72 /// platforms. 73 static void InvalidateInstructionCache(const void *Addr, size_t Len); 74 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); 79 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); 84 85 /// setRangeExecutable - Mark the page containing a range of addresses 86 /// as executable. 87 static bool setRangeExecutable(const void *Addr, size_t Size); 88 89 /// setRangeWritable - Mark the page containing a range of addresses 90 /// as writable. 91 static bool setRangeWritable(const void *Addr, size_t Size); 92 }; 93 } 94 } 95 96 #endif 97
