1//===- SearchForAddressOfSpecialSymbol.cpp - Function addresses -*- 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 pulls the addresses of certain symbols out of the linker.  It must
11//  include as few header files as possible because it declares the symbols as
12//  void*, which would conflict with the actual symbol type if any header
13//  declared it.
14//
15//===----------------------------------------------------------------------===//
16
17#include <string.h>
18
19// Must declare the symbols in the global namespace.
20static void *DoSearch(const char* symbolName) {
21#define EXPLICIT_SYMBOL(SYM) \
22   extern void *SYM; if (!strcmp(symbolName, #SYM)) return &SYM
23
24  // If this is darwin, it has some funky issues, try to solve them here.  Some
25  // important symbols are marked 'private external' which doesn't allow
26  // SearchForAddressOfSymbol to find them.  As such, we special case them here,
27  // there is only a small handful of them.
28
29#ifdef __APPLE__
30  {
31    // __eprintf is sometimes used for assert() handling on x86.
32    //
33    // FIXME: Currently disabled when using Clang, as we don't always have our
34    // runtime support libraries available.
35#ifndef __clang__
36#ifdef __i386__
37    EXPLICIT_SYMBOL(__eprintf);
38#endif
39#endif
40  }
41#endif
42
43#ifdef __CYGWIN__
44  {
45    EXPLICIT_SYMBOL(_alloca);
46    EXPLICIT_SYMBOL(__main);
47  }
48#endif
49
50#undef EXPLICIT_SYMBOL
51  return nullptr;
52}
53
54namespace llvm {
55void *SearchForAddressOfSpecialSymbol(const char* symbolName) {
56  return DoSearch(symbolName);
57}
58}  // namespace llvm
59