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1 /* Function return value location for Linux/SH ABI.
2    Copyright (C) 2010, 2014 Red Hat, Inc.
3    This file is part of elfutils.
4    Contributed by Matt Fleming <matt@console-pimps.org>.
5 
6    This file is free software; you can redistribute it and/or modify
7    it under the terms of either
8 
9      * the GNU Lesser General Public License as published by the Free
10        Software Foundation; either version 3 of the License, or (at
11        your option) any later version
12 
13    or
14 
15      * the GNU General Public License as published by the Free
16        Software Foundation; either version 2 of the License, or (at
17        your option) any later version
18 
19    or both in parallel, as here.
20 
21    elfutils is distributed in the hope that it will be useful, but
22    WITHOUT ANY WARRANTY; without even the implied warranty of
23    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
24    General Public License for more details.
25 
26    You should have received copies of the GNU General Public License and
27    the GNU Lesser General Public License along with this program.  If
28    not, see <http://www.gnu.org/licenses/>.  */
29 
30 #ifdef HAVE_CONFIG_H
31 # include <config.h>
32 #endif
33 
34 #include <assert.h>
35 #include <dwarf.h>
36 
37 #define BACKEND sh_
38 #include "libebl_CPU.h"
39 
40 
41 /* This is the SVR4 ELF ABI convention, but AIX and Linux do not use it.  */
42 #define SVR4_STRUCT_RETURN 0
43 
44 
45 /* r0, or pair r0, r1.  */
46 static const Dwarf_Op loc_intreg[] =
47   {
48     { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 4 },
49     { .atom = DW_OP_reg1 }, { .atom = DW_OP_piece, .number = 4 },
50   };
51 #define nloc_intreg	1
52 #define nloc_intregpair	4
53 
54 /* fr0 or fr1.  */
55 static const Dwarf_Op loc_fpreg[] =
56   {
57     { .atom = DW_OP_reg25 }, { .atom = DW_OP_piece, .number = 4 },
58     { .atom = DW_OP_reg26 }, { .atom = DW_OP_piece, .number = 4 },
59   };
60 #define nloc_fpreg	1
61 #define nloc_fpregpair	2
62 
63 int
sh_return_value_location(Dwarf_Die * functypedie,const Dwarf_Op ** locp)64 sh_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
65 {
66   /* Start with the function's type, and get the DW_AT_type attribute,
67      which is the type of the return value.  */
68   Dwarf_Die die_mem, *typedie = &die_mem;
69   int tag = dwarf_peeled_die_type (functypedie, typedie);
70   if (tag <= 0)
71     return tag;
72 
73   Dwarf_Word size;
74   switch (tag)
75     {
76     case -1:
77       return -1;
78 
79     case DW_TAG_subrange_type:
80       if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
81 	{
82 	  Dwarf_Attribute attr_mem, *attr;
83 	  attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
84 	  typedie = dwarf_formref_die (attr, &die_mem);
85 	  tag = DWARF_TAG_OR_RETURN (typedie);
86 	}
87       FALLTHROUGH;
88 
89     case DW_TAG_base_type:
90     case DW_TAG_enumeration_type:
91     case DW_TAG_pointer_type:
92     case DW_TAG_ptr_to_member_type:
93       {
94 	Dwarf_Attribute attr_mem;
95 	if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
96 						   &attr_mem), &size) != 0)
97 	  {
98 	    if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
99 	      size = 4;
100 	    else
101 	      return -1;
102 	  }
103       }
104 
105       if (size <= 8)
106 	{
107 	  if (tag == DW_TAG_base_type)
108 	    {
109 	      Dwarf_Attribute attr_mem;
110 	      Dwarf_Word encoding;
111 	      if (dwarf_formudata (dwarf_attr_integrate (typedie,
112 							 DW_AT_encoding,
113 							 &attr_mem),
114 				   &encoding) != 0)
115 		return -1;
116 	      if (encoding == DW_ATE_float)
117 		{
118 		  *locp = loc_fpreg;
119 		  return size <= 4 ? nloc_fpreg : nloc_fpregpair;
120 		}
121 	    }
122 	  *locp = loc_intreg;
123 	  return size <= 4 ? nloc_intreg : nloc_intregpair;
124 	}
125     }
126 
127   /* XXX We don't have a good way to return specific errors from ebl calls.
128      This value means we do not understand the type, but it is well-formed
129      DWARF and might be valid.  */
130   return -2;
131 }
132