Line data    Source code

       1             : /* Function return value location for ARM EABI.
       2             :    Copyright (C) 2009-2010, 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 arm_
      37             : #include "libebl_CPU.h"
      38             : 
      39             : 
      40             : /* r0, or pair r0, r1, or aggregate up to r0-r3.  */
      41             : static const Dwarf_Op loc_intreg[] =
      42             :   {
      43             :     { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 4 },
      44             :     { .atom = DW_OP_reg1 }, { .atom = DW_OP_piece, .number = 4 },
      45             :     { .atom = DW_OP_reg2 }, { .atom = DW_OP_piece, .number = 4 },
      46             :     { .atom = DW_OP_reg3 }, { .atom = DW_OP_piece, .number = 4 },
      47             :   };
      48             : #define nloc_intreg     1
      49             : #define nloc_intregs(n) (2 * (n))
      50             : 
      51             : /* The return value is a structure and is actually stored in stack space
      52             :    passed in a hidden argument by the caller.  But, the compiler
      53             :    helpfully returns the address of that space in r0.  */
      54             : static const Dwarf_Op loc_aggregate[] =
      55             :   {
      56             :     { .atom = DW_OP_breg0, .number = 0 }
      57             :   };
      58             : #define nloc_aggregate 1
      59             : 
      60             : 
      61             : int
      62           0 : arm_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
      63             : {
      64             :   /* Start with the function's type, and get the DW_AT_type attribute,
      65             :      which is the type of the return value.  */
      66           0 :   Dwarf_Die die_mem, *typedie = &die_mem;
      67           0 :   int tag = dwarf_peeled_die_type (functypedie, typedie);
      68           0 :   if (tag <= 0)
      69             :     return tag;
      70             : 
      71           0 :   Dwarf_Word size;
      72           0 :   switch (tag)
      73             :     {
      74             :     case -1:
      75             :       return -1;
      76             : 
      77           0 :     case DW_TAG_subrange_type:
      78           0 :       if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
      79             :         {
      80           0 :           Dwarf_Attribute attr_mem, *attr;
      81           0 :           attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
      82           0 :           typedie = dwarf_formref_die (attr, &die_mem);
      83           0 :           tag = DWARF_TAG_OR_RETURN (typedie);
      84             :         }
      85           0 :       FALLTHROUGH;
      86             : 
      87             :     case DW_TAG_base_type:
      88             :     case DW_TAG_enumeration_type:
      89             :     case DW_TAG_pointer_type:
      90             :     case DW_TAG_ptr_to_member_type:
      91             :       {
      92           0 :         Dwarf_Attribute attr_mem;
      93           0 :         if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
      94             :                                                    &attr_mem), &size) != 0)
      95             :           {
      96           0 :             if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
      97           0 :               size = 4;
      98             :             else
      99             :               return -1;
     100             :           }
     101           0 :         if (size <= 16)
     102             :           {
     103           0 :           intreg:
     104           0 :             *locp = loc_intreg;
     105           0 :             return size <= 4 ? nloc_intreg : nloc_intregs ((size + 3) / 4);
     106             :           }
     107             : 
     108           0 :       aggregate:
     109           0 :         *locp = loc_aggregate;
     110           0 :         return nloc_aggregate;
     111             :       }
     112             : 
     113           0 :     case DW_TAG_structure_type:
     114             :     case DW_TAG_class_type:
     115             :     case DW_TAG_union_type:
     116             :     case DW_TAG_array_type:
     117           0 :       if (dwarf_aggregate_size (typedie, &size) == 0
     118           0 :           && size > 0 && size <= 4)
     119             :         goto intreg;
     120             :       goto aggregate;
     121             :     }
     122             : 
     123             :   /* XXX We don't have a good way to return specific errors from ebl calls.
     124             :      This value means we do not understand the type, but it is well-formed
     125             :      DWARF and might be valid.  */
     126           0 :   return -2;
     127             : }