gcc/config/mips/irix6-libc-compat.c

   1 /* Compensate for inconsistent structure return conventions on IRIX 6.  */
   2 /* Compile this one with gcc.  */
   3 /* Copyright (C) 2001  Free Software Foundation, Inc.
   4
   5 This file is part of GNU CC.
   6
   7 GNU CC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 In addition to the permissions in the GNU General Public License, the
  13 Free Software Foundation gives you unlimited permission to link the
  14 compiled version of this file into combinations with other programs,
  15 and to distribute those combinations without any restriction coming
  16 from the use of this file.  (The General Public License restrictions
  17 do apply in other respects; for example, they cover modification of
  18 the file, and distribution when not linked into a combine
  19 executable.)
  20
  21 GNU CC is distributed in the hope that it will be useful,
  22 but WITHOUT ANY WARRANTY; without even the implied warranty of
  23 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  24 GNU General Public License for more details.
  25
  26 You should have received a copy of the GNU General Public License
  27 along with GNU CC; see the file COPYING.  If not, write to
  28 the Free Software Foundation, 59 Temple Place - Suite 330,
  29 Boston, MA 02111-1307, USA.  */
  30
  31 /* GCC doesn't correctly implement the structure and union return
  32    conventions of the N32 and N64 ABIs on IRIX 6, as described in the
  33    MIPSpro N32 ABI Handbook, ch. 2, Calling Convention Implementations, p.7.
  34    The ABI requires that structures (or trailing parts of structures) smaller
  35    than 8 bytes (a 64-bit register) are left-justified, whereas GCC
  36    right-justifies them.
  37
  38    While GCC is internally consistent, calling routines compiled with a
  39    compiler that does implement the documented ABI (like SGIs MIPSpro C
  40    compiler) doesn't work.  This is primarily an issue for system libraries
  41    like libc.  Fortunately, there exist only very few routines that return
  42    structures by value, so until the underlying bug is fixed, it is possible
  43    to work around it by providing wrappers for the few affected routines.
  44
  45    These wrappers rely on the fact that e.g. libc contains weak versions of
  46    those routines, and the real implementation is provided by _-prefixed
  47    variants.  So we can provide our own versions, which will only be linked
  48    if the application uses any of the affected functions, calling the private
  49    variants and then shifting the result as required.
  50
  51    This is a rewrite of code created by Andy Polyakov.  */
  52
  53 #include "config.h"
  54 #include "system.h"
  55 #include "coretypes.h"
  56 #include "tm.h"
  57
  58 /* This must only be used for the N32 and N64 ABIs.  O32 is correct.  */
  59
  60 #if _MIPS_SIM == _ABIN32 || _MIPS_SIM == _ABI64
  61
  62 /* The affected return values need to be shifted by
  63
  64         BITS_PER_WORD - (sizeof (value) * BITS_PER_UNIT).
  65
  66    Since only 32-bit results are involved, the shift count is always 32.  */
  67 #define SHIFT_BITS      32
  68
  69 extern machreg_t _inet_makeaddr (machreg_t, machreg_t);
  70
  71 /* <arpa/inet.h> has
  72
  73         struct in_addr inet_makeaddr (int, int);                (IRIX 6.2)
  74         struct in_addr inet_makeaddr (in_addr_t, in_addr_t);    (IRIX 6.5)  */
  75
  76 machreg_t
  77 inet_makeaddr (machreg_t net, machreg_t lna)
  78 {
  79   return _inet_makeaddr (net, lna) >> SHIFT_BITS;
  80 }
  81
  82 #endif /* _ABIN32 || _ABI64 */