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