lib/System/SearchForAddressOfSpecialSymbol.cpp

   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.
  20 static 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 #ifdef __i386__
  48     EXPLICIT_SYMBOL(__eprintf);
  49 #endif
  50   }
  51 #endif
  52
  53 #ifdef __CYGWIN__
  54   {
  55     EXPLICIT_SYMBOL(_alloca);
  56     EXPLICIT_SYMBOL(__main);
  57   }
  58 #endif
  59
  60 #undef EXPLICIT_SYMBOL
  61   return 0;
  62 }
  63
  64 namespace llvm {
  65 void *SearchForAddressOfSpecialSymbol(const char* symbolName) {
  66   return DoSearch(symbolName);
  67 }
  68 }  // namespace llvm