1//===----------- JITSymbol.h - JIT symbol abstraction -----------*- 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// Abstraction for target process addresses.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_EXECUTIONENGINE_ORC_JITSYMBOL_H
15#define LLVM_EXECUTIONENGINE_ORC_JITSYMBOL_H
16
17#include "llvm/ExecutionEngine/JITSymbolFlags.h"
18#include "llvm/Support/DataTypes.h"
19#include <cassert>
20#include <functional>
21
22namespace llvm {
23namespace orc {
24
25/// @brief Represents an address in the target process's address space.
26typedef uint64_t TargetAddress;
27
28/// @brief Represents a symbol in the JIT.
29class JITSymbol : public JITSymbolBase {
30public:
31
32  typedef std::function<TargetAddress()> GetAddressFtor;
33
34  /// @brief Create a 'null' symbol that represents failure to find a symbol
35  ///        definition.
36  JITSymbol(std::nullptr_t)
37      : JITSymbolBase(JITSymbolFlags::None), CachedAddr(0) {}
38
39  /// @brief Create a symbol for a definition with a known address.
40  JITSymbol(TargetAddress Addr, JITSymbolFlags Flags)
41    : JITSymbolBase(Flags), CachedAddr(Addr) {}
42
43  /// @brief Create a symbol for a definition that doesn't have a known address
44  ///        yet.
45  /// @param GetAddress A functor to materialize a definition (fixing the
46  ///        address) on demand.
47  ///
48  ///   This constructor allows a JIT layer to provide a reference to a symbol
49  /// definition without actually materializing the definition up front. The
50  /// user can materialize the definition at any time by calling the getAddress
51  /// method.
52  JITSymbol(GetAddressFtor GetAddress, JITSymbolFlags Flags)
53      : JITSymbolBase(Flags), GetAddress(std::move(GetAddress)), CachedAddr(0) {}
54
55  /// @brief Returns true if the symbol exists, false otherwise.
56  explicit operator bool() const { return CachedAddr || GetAddress; }
57
58  /// @brief Get the address of the symbol in the target address space. Returns
59  ///        '0' if the symbol does not exist.
60  TargetAddress getAddress() {
61    if (GetAddress) {
62      CachedAddr = GetAddress();
63      assert(CachedAddr && "Symbol could not be materialized.");
64      GetAddress = nullptr;
65    }
66    return CachedAddr;
67  }
68
69private:
70  GetAddressFtor GetAddress;
71  TargetAddress CachedAddr;
72};
73
74} // End namespace orc.
75} // End namespace llvm.
76
77#endif // LLVM_EXECUTIONENGINE_ORC_JITSYMBOL_H
78