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97 lines
3.7 KiB
C++
97 lines
3.7 KiB
C++
//===- llvm/Support/Memory.h - Memory Support --------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file declares the llvm::sys::Memory class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SYSTEM_MEMORY_H
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#define LLVM_SYSTEM_MEMORY_H
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#include "llvm/Support/DataTypes.h"
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#include <string>
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namespace llvm {
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namespace sys {
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/// This class encapsulates the notion of a memory block which has an address
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/// and a size. It is used by the Memory class (a friend) as the result of
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/// various memory allocation operations.
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/// @see Memory
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/// @brief Memory block abstraction.
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class MemoryBlock {
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public:
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MemoryBlock() : Address(0), Size(0) { }
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MemoryBlock(void *addr, size_t size) : Address(addr), Size(size) { }
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void *base() const { return Address; }
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size_t size() const { return Size; }
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private:
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void *Address; ///< Address of first byte of memory area
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size_t Size; ///< Size, in bytes of the memory area
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friend class Memory;
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};
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/// This class provides various memory handling functions that manipulate
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/// MemoryBlock instances.
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/// @since 1.4
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/// @brief An abstraction for memory operations.
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class Memory {
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public:
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/// This method allocates a block of Read/Write/Execute memory that is
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/// suitable for executing dynamically generated code (e.g. JIT). An
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/// attempt to allocate \p NumBytes bytes of virtual memory is made.
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/// \p NearBlock may point to an existing allocation in which case
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/// an attempt is made to allocate more memory near the existing block.
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///
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/// On success, this returns a non-null memory block, otherwise it returns
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/// a null memory block and fills in *ErrMsg.
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///
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/// @brief Allocate Read/Write/Execute memory.
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static MemoryBlock AllocateRWX(size_t NumBytes,
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const MemoryBlock *NearBlock,
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std::string *ErrMsg = 0);
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/// This method releases a block of Read/Write/Execute memory that was
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/// allocated with the AllocateRWX method. It should not be used to
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/// release any memory block allocated any other way.
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///
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/// On success, this returns false, otherwise it returns true and fills
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/// in *ErrMsg.
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/// @brief Release Read/Write/Execute memory.
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static bool ReleaseRWX(MemoryBlock &block, std::string *ErrMsg = 0);
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/// InvalidateInstructionCache - Before the JIT can run a block of code
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/// that has been emitted it must invalidate the instruction cache on some
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/// platforms.
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static void InvalidateInstructionCache(const void *Addr, size_t Len);
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/// setExecutable - Before the JIT can run a block of code, it has to be
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/// given read and executable privilege. Return true if it is already r-x
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/// or the system is able to change its previlege.
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static bool setExecutable(MemoryBlock &M, std::string *ErrMsg = 0);
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/// setWritable - When adding to a block of code, the JIT may need
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/// to mark a block of code as RW since the protections are on page
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/// boundaries, and the JIT internal allocations are not page aligned.
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static bool setWritable(MemoryBlock &M, std::string *ErrMsg = 0);
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/// setRangeExecutable - Mark the page containing a range of addresses
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/// as executable.
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static bool setRangeExecutable(const void *Addr, size_t Size);
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/// setRangeWritable - Mark the page containing a range of addresses
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/// as writable.
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static bool setRangeWritable(const void *Addr, size_t Size);
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};
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}
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}
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#endif
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