SearchForAddressOfSpecialSymbol.cpp revision 218885 
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    EXPLICIT_SYMBOL(__ashldi3);
32    EXPLICIT_SYMBOL(__ashrdi3);
33    EXPLICIT_SYMBOL(__cmpdi2);
34    EXPLICIT_SYMBOL(__divdi3);
35    EXPLICIT_SYMBOL(__fixdfdi);
36    EXPLICIT_SYMBOL(__fixsfdi);
37    EXPLICIT_SYMBOL(__fixunsdfdi);
38    EXPLICIT_SYMBOL(__fixunssfdi);
39    EXPLICIT_SYMBOL(__floatdidf);
40    EXPLICIT_SYMBOL(__floatdisf);
41    EXPLICIT_SYMBOL(__lshrdi3);
42    EXPLICIT_SYMBOL(__moddi3);
43    EXPLICIT_SYMBOL(__udivdi3);
44    EXPLICIT_SYMBOL(__umoddi3);
45
46    // __eprintf is sometimes used for assert() handling on x86.
47    //
48    // FIXME: Currently disabled when using Clang, as we don't always have our
49    // runtime support libraries available.
50#ifndef __clang__
51#ifdef __i386__
52    EXPLICIT_SYMBOL(__eprintf);
53#endif
54#endif
55  }
56#endif
57
58#ifdef __CYGWIN__
59  {
60    EXPLICIT_SYMBOL(_alloca);
61    EXPLICIT_SYMBOL(__main);
62  }
63#endif
64
65#undef EXPLICIT_SYMBOL
66  return 0;
67}
68
69namespace llvm {
70void *SearchForAddressOfSpecialSymbol(const char* symbolName) {
71  return DoSearch(symbolName);
72}
73}  // namespace llvm
74