Line data    Source code

       1             : /* Function return value location for Linux/i386 ABI.
       2             :    Copyright (C) 2005-2010, 2014 Red Hat, Inc.
       3             :    This file is part of elfutils.
       4             : 
       5             :    This file is free software; you can redistribute it and/or modify
       6             :    it under the terms of either
       7             : 
       8             :      * the GNU Lesser General Public License as published by the Free
       9             :        Software Foundation; either version 3 of the License, or (at
      10             :        your option) any later version
      11             : 
      12             :    or
      13             : 
      14             :      * the GNU General Public License as published by the Free
      15             :        Software Foundation; either version 2 of the License, or (at
      16             :        your option) any later version
      17             : 
      18             :    or both in parallel, as here.
      19             : 
      20             :    elfutils is distributed in the hope that it will be useful, but
      21             :    WITHOUT ANY WARRANTY; without even the implied warranty of
      22             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      23             :    General Public License for more details.
      24             : 
      25             :    You should have received copies of the GNU General Public License and
      26             :    the GNU Lesser General Public License along with this program.  If
      27             :    not, see <http://www.gnu.org/licenses/>.  */
      28             : 
      29             : #ifdef HAVE_CONFIG_H
      30             : # include <config.h>
      31             : #endif
      32             : 
      33             : #include <assert.h>
      34             : #include <dwarf.h>
      35             : 
      36             : #define BACKEND i386_
      37             : #include "libebl_CPU.h"
      38             : 
      39             : 
      40             : /* %eax, or pair %eax, %edx.  */
      41             : static const Dwarf_Op loc_intreg[] =
      42             :   {
      43             :     { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 4 },
      44             :     { .atom = DW_OP_reg2 }, { .atom = DW_OP_piece, .number = 4 },
      45             :   };
      46             : #define nloc_intreg     1
      47             : #define nloc_intregpair 4
      48             : 
      49             : /* %st(0).  */
      50             : static const Dwarf_Op loc_fpreg[] =
      51             :   {
      52             :     { .atom = DW_OP_reg11 }
      53             :   };
      54             : #define nloc_fpreg      1
      55             : 
      56             : /* The return value is a structure and is actually stored in stack space
      57             :    passed in a hidden argument by the caller.  But, the compiler
      58             :    helpfully returns the address of that space in %eax.  */
      59             : static const Dwarf_Op loc_aggregate[] =
      60             :   {
      61             :     { .atom = DW_OP_breg0, .number = 0 }
      62             :   };
      63             : #define nloc_aggregate 1
      64             : 
      65             : int
      66           0 : i386_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
      67             : {
      68             :   /* Start with the function's type, and get the DW_AT_type attribute,
      69             :      which is the type of the return value.  */
      70           0 :   Dwarf_Die die_mem, *typedie = &die_mem;
      71           0 :   int tag = dwarf_peeled_die_type (functypedie, typedie);
      72           0 :   if (tag <= 0)
      73             :     return tag;
      74             : 
      75           0 :   switch (tag)
      76             :     {
      77             :     case -1:
      78             :       return -1;
      79             : 
      80           0 :     case DW_TAG_subrange_type:
      81           0 :       if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
      82             :         {
      83           0 :           Dwarf_Attribute attr_mem, *attr;
      84           0 :           attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
      85           0 :           typedie = dwarf_formref_die (attr, &die_mem);
      86           0 :           tag = DWARF_TAG_OR_RETURN (typedie);
      87             :         }
      88           0 :       FALLTHROUGH;
      89             : 
      90             :     case DW_TAG_base_type:
      91             :     case DW_TAG_enumeration_type:
      92             :     case DW_TAG_pointer_type:
      93             :     case DW_TAG_ptr_to_member_type:
      94           0 :       {
      95           0 :         Dwarf_Word size;
      96           0 :         Dwarf_Attribute attr_mem;
      97           0 :         if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
      98             :                                                    &attr_mem), &size) != 0)
      99             :           {
     100           0 :             if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
     101           0 :               size = 4;
     102             :             else
     103           0 :               return -1;
     104             :           }
     105           0 :         if (tag == DW_TAG_base_type)
     106             :           {
     107           0 :             Dwarf_Word encoding;
     108           0 :             if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
     109             :                                                        &attr_mem),
     110             :                                  &encoding) != 0)
     111           0 :               return -1;
     112           0 :             if (encoding == DW_ATE_float)
     113             :               {
     114           0 :                 if (size > 16)
     115             :                   return -2;
     116           0 :                 *locp = loc_fpreg;
     117           0 :                 return nloc_fpreg;
     118             :               }
     119             :           }
     120           0 :         *locp = loc_intreg;
     121           0 :         if (size <= 4)
     122             :           return nloc_intreg;
     123           0 :         if (size <= 8)
     124             :           return nloc_intregpair;
     125             :       }
     126           0 :     FALLTHROUGH;
     127             : 
     128             :     case DW_TAG_structure_type:
     129             :     case DW_TAG_class_type:
     130             :     case DW_TAG_union_type:
     131             :     case DW_TAG_array_type:
     132           0 :       *locp = loc_aggregate;
     133           0 :       return nloc_aggregate;
     134             :     }
     135             : 
     136             :   /* XXX We don't have a good way to return specific errors from ebl calls.
     137             :      This value means we do not understand the type, but it is well-formed
     138             :      DWARF and might be valid.  */
     139           0 :   return -2;
     140             : }