LCOV - code coverage report
Current view: top level - backends - x86_64_retval.c (source / functions) Hit Total Coverage
Test: elfutils-0.178 Lines: 33 52 63.5 %
Date: 2019-11-26 23:55:16 Functions: 1 1 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /* Function return value location for Linux/x86-64 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 x86_64_
      37             : #include "libebl_CPU.h"
      38             : 
      39             : 
      40             : /* %rax, or pair %rax, %rdx.  */
      41             : static const Dwarf_Op loc_intreg[] =
      42             :   {
      43             :     { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 8 },
      44             :     { .atom = DW_OP_reg1 }, { .atom = DW_OP_piece, .number = 8 },
      45             :   };
      46             : #define nloc_intreg     1
      47             : #define nloc_intregpair 4
      48             : 
      49             : /* %st(0), or pair %st(0), %st(1).  */
      50             : static const Dwarf_Op loc_x87reg[] =
      51             :   {
      52             :     { .atom = DW_OP_regx, .number = 33 },
      53             :     { .atom = DW_OP_piece, .number = 10 },
      54             :     { .atom = DW_OP_regx, .number = 34 },
      55             :     { .atom = DW_OP_piece, .number = 10 },
      56             :   };
      57             : #define nloc_x87reg     1
      58             : #define nloc_x87regpair 4
      59             : 
      60             : /* %xmm0, or pair %xmm0, %xmm1.  */
      61             : static const Dwarf_Op loc_ssereg[] =
      62             :   {
      63             :     { .atom = DW_OP_reg17 }, { .atom = DW_OP_piece, .number = 16 },
      64             :     { .atom = DW_OP_reg18 }, { .atom = DW_OP_piece, .number = 16 },
      65             :   };
      66             : #define nloc_ssereg     1
      67             : #define nloc_sseregpair 4
      68             : 
      69             : /* The return value is a structure and is actually stored in stack space
      70             :    passed in a hidden argument by the caller.  But, the compiler
      71             :    helpfully returns the address of that space in %rax.  */
      72             : static const Dwarf_Op loc_aggregate[] =
      73             :   {
      74             :     { .atom = DW_OP_breg0, .number = 0 }
      75             :   };
      76             : #define nloc_aggregate 1
      77             : 
      78             : 
      79             : int
      80       10424 : x86_64_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
      81             : {
      82             :   /* Start with the function's type, and get the DW_AT_type attribute,
      83             :      which is the type of the return value.  */
      84       10424 :   Dwarf_Die die_mem, *typedie = &die_mem;
      85       10424 :   int tag = dwarf_peeled_die_type (functypedie, typedie);
      86       10424 :   if (tag <= 0)
      87             :     return tag;
      88             : 
      89        8331 :   Dwarf_Word size;
      90        8331 :   switch (tag)
      91             :     {
      92             :     case -1:
      93             :       return -1;
      94             : 
      95           0 :     case DW_TAG_subrange_type:
      96           0 :       if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
      97             :         {
      98           0 :           Dwarf_Attribute attr_mem, *attr;
      99           0 :           attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
     100           0 :           typedie = dwarf_formref_die (attr, &die_mem);
     101           0 :           tag = DWARF_TAG_OR_RETURN (typedie);
     102             :         }
     103        8263 :       FALLTHROUGH;
     104             : 
     105             :     case DW_TAG_base_type:
     106             :     case DW_TAG_enumeration_type:
     107             :     case DW_TAG_pointer_type:
     108             :     case DW_TAG_ptr_to_member_type:
     109        8263 :       {
     110        8263 :         Dwarf_Attribute attr_mem;
     111        8263 :         if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
     112             :                                                    &attr_mem), &size) != 0)
     113             :           {
     114           0 :             if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
     115           0 :               size = 8;
     116             :             else
     117           0 :               return -1;
     118             :           }
     119             :       }
     120             : 
     121        8263 :       if (tag == DW_TAG_base_type)
     122             :         {
     123        5967 :           Dwarf_Attribute attr_mem;
     124        5967 :           Dwarf_Word encoding;
     125        5967 :           if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
     126             :                                                      &attr_mem),
     127             :                                &encoding) != 0)
     128         190 :             return -1;
     129             : 
     130        5967 :           switch (encoding)
     131             :             {
     132           0 :             case DW_ATE_complex_float:
     133           0 :               switch (size)
     134             :                 {
     135           0 :                 case 4 * 2:     /* complex float */
     136             :                 case 8 * 2:     /* complex double */
     137           0 :                   *locp = loc_ssereg;
     138           0 :                   return nloc_sseregpair;
     139           0 :                 case 16 * 2:    /* complex long double */
     140           0 :                   *locp = loc_x87reg;
     141           0 :                   return nloc_x87regpair;
     142             :                 }
     143             :               return -2;
     144             : 
     145         190 :             case DW_ATE_float:
     146         190 :               switch (size)
     147             :                 {
     148         100 :                 case 4: /* float */
     149             :                 case 8: /* double */
     150         100 :                   *locp = loc_ssereg;
     151         100 :                   return nloc_ssereg;
     152          90 :                 case 16:        /* long double */
     153             :                   /* XXX distinguish __float128, which is sseregpair?? */
     154          90 :                   *locp = loc_x87reg;
     155          90 :                   return nloc_x87reg;
     156             :                 }
     157             :               return -2;
     158             :             }
     159             :         }
     160             : 
     161        2296 :     intreg:
     162        8139 :       *locp = loc_intreg;
     163        8139 :       if (size <= 8)
     164             :         return nloc_intreg;
     165          62 :       if (size <= 16)
     166             :         return nloc_intregpair;
     167             : 
     168           0 :     large:
     169           2 :       *locp = loc_aggregate;
     170           2 :       return nloc_aggregate;
     171             : 
     172          68 :     case DW_TAG_structure_type:
     173             :     case DW_TAG_class_type:
     174             :     case DW_TAG_union_type:
     175             :     case DW_TAG_array_type:
     176          68 :       if (dwarf_aggregate_size (typedie, &size) != 0)
     177             :         goto large;
     178          68 :       if (size > 16)
     179             :         goto large;
     180             : 
     181             :       /* XXX
     182             :          Must examine the fields in picayune ways to determine the
     183             :          actual answer.  This will be right for small C structs
     184             :          containing integer types and similarly simple cases.
     185             :       */
     186             : 
     187             :       goto intreg;
     188             :     }
     189             : 
     190             :   /* XXX We don't have a good way to return specific errors from ebl calls.
     191             :      This value means we do not understand the type, but it is well-formed
     192             :      DWARF and might be valid.  */
     193           0 :   return -2;
     194             : }

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