1/* Function return value location for SPARC.
2   Copyright (C) 2006-2010, 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 sparc_
37#include "libebl_CPU.h"
38
39
40/* %o0, or pair %o0, %o1.  */
41static const Dwarf_Op loc_intreg[] =
42  {
43    { .atom = DW_OP_reg8 }, { .atom = DW_OP_piece, .number = 4 },
44    { .atom = DW_OP_reg9 }, { .atom = DW_OP_piece, .number = 4 },
45  };
46#define nloc_intreg	1
47#define nloc_intregpair	4
48
49/* %f0 or pair %f0, %f1, or quad %f0..%f3.  */
50static const Dwarf_Op loc_fpreg[] =
51  {
52    { .atom = DW_OP_regx, .number = 32 }, { .atom = DW_OP_piece, .number = 4 },
53    { .atom = DW_OP_regx, .number = 33 }, { .atom = DW_OP_piece, .number = 4 },
54    { .atom = DW_OP_regx, .number = 34 }, { .atom = DW_OP_piece, .number = 4 },
55    { .atom = DW_OP_regx, .number = 35 }, { .atom = DW_OP_piece, .number = 4 },
56  };
57#define nloc_fpreg	1
58#define nloc_fpregpair	4
59#define nloc_fpregquad	8
60
61/* The return value is a structure and is actually stored in stack space
62   passed in a hidden argument by the caller.  But, the compiler
63   helpfully returns the address of that space in %o0.  */
64static const Dwarf_Op loc_aggregate[] =
65  {
66    { .atom = DW_OP_breg8, .number = 0 }
67  };
68#define nloc_aggregate 1
69
70int
71sparc_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
72{
73  /* Start with the function's type, and get the DW_AT_type attribute,
74     which is the type of the return value.  */
75  Dwarf_Die die_mem, *typedie = &die_mem;
76  int tag = dwarf_peeled_die_type (functypedie, typedie);
77  if (tag <= 0)
78    return tag;
79
80  Dwarf_Word size;
81  switch (tag)
82    {
83    case -1:
84      return -1;
85
86    case DW_TAG_subrange_type:
87      if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
88	{
89	  Dwarf_Attribute attr_mem, *attr;
90	  attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
91	  typedie = dwarf_formref_die (attr, &die_mem);
92	  tag = DWARF_TAG_OR_RETURN (typedie);
93	}
94      /* Fall through.  */
95
96    case DW_TAG_base_type:
97    case DW_TAG_enumeration_type:
98    case DW_TAG_pointer_type:
99    case DW_TAG_ptr_to_member_type:
100      {
101	Dwarf_Attribute attr_mem;
102	if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
103						   &attr_mem), &size) != 0)
104	  {
105	    uint8_t asize;
106	    Dwarf_Die cudie;
107	    if ((tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
108		&& dwarf_diecu (typedie, &cudie, &asize, NULL) != NULL)
109	      size = asize;
110	    else
111	      return -1;
112	  }
113      }
114
115      if (tag == DW_TAG_base_type)
116	{
117	  Dwarf_Attribute attr_mem;
118	  Dwarf_Word encoding;
119	  if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
120						     &attr_mem),
121			       &encoding) != 0)
122	    return -1;
123	  if (encoding == DW_ATE_float)
124	    {
125	      *locp = loc_fpreg;
126	      if (size <= 4)
127		return nloc_fpreg;
128	      if (size <= 8)
129		return nloc_fpregpair;
130	      if (size <= 16)
131		return nloc_fpregquad;
132	    }
133	}
134      if (size <= 8)
135	{
136	intreg:
137	  *locp = loc_intreg;
138	  return size <= 4 ? nloc_intreg : nloc_intregpair;
139	}
140
141    aggregate:
142      *locp = loc_aggregate;
143      return nloc_aggregate;
144
145    case DW_TAG_structure_type:
146    case DW_TAG_class_type:
147    case DW_TAG_union_type:
148    case DW_TAG_array_type:
149      if (dwarf_aggregate_size (typedie, &size) == 0
150	  && size > 0 && size <= 8)
151	goto intreg;
152      goto aggregate;
153    }
154
155  /* XXX We don't have a good way to return specific errors from ebl calls.
156     This value means we do not understand the type, but it is well-formed
157     DWARF and might be valid.  */
158  return -2;
159}
160