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//===----------- JITSymbol.h - JIT symbol abstraction -----------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Abstraction for target process addresses.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_EXECUTIONENGINE_ORC_JITSYMBOL_H
#define LLVM_EXECUTIONENGINE_ORC_JITSYMBOL_H
#include "llvm/Support/DataTypes.h"
#include <cassert>
#include <functional>
namespace llvm {
namespace orc {
/// @brief Represents an address in the target process's address space.
typedef uint64_t TargetAddress;
/// @brief Represents a symbol in the JIT.
class JITSymbol {
public:
typedef std::function<TargetAddress()> GetAddressFtor;
/// @brief Create a 'null' symbol that represents failure to find a symbol
/// definition.
JITSymbol(std::nullptr_t) : CachedAddr(0) {}
/// @brief Create a symbol for a definition with a known address.
JITSymbol(TargetAddress Addr)
: CachedAddr(Addr) {}
/// @brief Create a symbol for a definition that doesn't have a known address
/// yet.
/// @param GetAddress A functor to materialize a definition (fixing the
/// address) on demand.
///
/// This constructor allows a JIT layer to provide a reference to a symbol
/// definition without actually materializing the definition up front. The
/// user can materialize the definition at any time by calling the getAddress
/// method.
JITSymbol(GetAddressFtor GetAddress)
: CachedAddr(0), GetAddress(std::move(GetAddress)) {}
/// @brief Returns true if the symbol exists, false otherwise.
explicit operator bool() const { return CachedAddr || GetAddress; }
/// @brief Get the address of the symbol in the target address space. Returns
/// '0' if the symbol does not exist.
TargetAddress getAddress() {
if (GetAddress) {
CachedAddr = GetAddress();
assert(CachedAddr && "Symbol could not be materialized.");
GetAddress = nullptr;
}
return CachedAddr;
}
private:
TargetAddress CachedAddr;
GetAddressFtor GetAddress;
};
} // End namespace orc.
} // End namespace llvm.
#endif // LLVM_EXECUTIONENGINE_ORC_JITSYMBOL_H
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