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.  */
46static 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.  */
55static 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
63int
64sh_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      /* Fall through.  */
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