1 /* Function return value location for Linux/m68k ABI.
2 This file is part of elfutils.
3
4 This file is free software; you can redistribute it and/or modify
5 it under the terms of either
6
7 * the GNU Lesser General Public License as published by the Free
8 Software Foundation; either version 3 of the License, or (at
9 your option) any later version
10
11 or
12
13 * the GNU General Public License as published by the Free
14 Software Foundation; either version 2 of the License, or (at
15 your option) any later version
16
17 or both in parallel, as here.
18
19 elfutils is distributed in the hope that it will be useful, but
20 WITHOUT ANY WARRANTY; without even the implied warranty of
21 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22 General Public License for more details.
23
24 You should have received copies of the GNU General Public License and
25 the GNU Lesser General Public License along with this program. If
26 not, see <http://www.gnu.org/licenses/>. */
27
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 m68k_
37 #include "libebl_CPU.h"
38
39
40 /* %d0, or pair %d0, %d1. */
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 };
46 #define nloc_intreg 1
47 #define nloc_intregpair 4
48
49 /* %a0. */
50 static const Dwarf_Op loc_ptrreg[] =
51 {
52 { .atom = DW_OP_reg8 }
53 };
54 #define nloc_ptrreg 1
55
56 /* %fp0. */
57 static const Dwarf_Op loc_fpreg[] =
58 {
59 { .atom = DW_OP_reg16 }
60 };
61 #define nloc_fpreg 1
62
63 /* The return value is a structure and is actually stored in stack space
64 passed in a hidden argument by the caller. But, the compiler
65 helpfully returns the address of that space in %a0. */
66 static const Dwarf_Op loc_aggregate[] =
67 {
68 { .atom = DW_OP_reg8 }
69 };
70 #define nloc_aggregate 1
71
72 int
m68k_return_value_location(Dwarf_Die * functypedie,const Dwarf_Op ** locp)73 m68k_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
74 {
75 /* Start with the function's type, and get the DW_AT_type attribute,
76 which is the type of the return value. */
77 Dwarf_Die die_mem, *typedie = &die_mem;
78 int tag = dwarf_peeled_die_type (functypedie, typedie);
79 if (tag <= 0)
80 return tag;
81
82 switch (tag)
83 {
84 case -1:
85 return -1;
86
87 case DW_TAG_subrange_type:
88 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
89 {
90 Dwarf_Attribute attr_mem, *attr;
91 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
92 typedie = dwarf_formref_die (attr, &die_mem);
93 tag = DWARF_TAG_OR_RETURN (typedie);
94 }
95 FALLTHROUGH;
96
97 case DW_TAG_base_type:
98 case DW_TAG_enumeration_type:
99 CASE_POINTER:
100 {
101 Dwarf_Word size;
102 Dwarf_Attribute attr_mem;
103 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
104 &attr_mem), &size) != 0)
105 {
106 if (dwarf_is_pointer (tag))
107 size = 4;
108 else
109 return -1;
110 }
111 if (tag == DW_TAG_base_type)
112 {
113 Dwarf_Word encoding;
114 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
115 &attr_mem),
116 &encoding) != 0)
117 return -1;
118 if (encoding == DW_ATE_float)
119 {
120 if (size > 12)
121 return -2;
122 *locp = loc_fpreg;
123 return nloc_fpreg;
124 }
125 }
126 if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
127 {
128 *locp = loc_ptrreg;
129 return nloc_ptrreg;
130 }
131 *locp = loc_intreg;
132 if (size <= 4)
133 return nloc_intreg;
134 if (size <= 8)
135 return nloc_intregpair;
136 }
137 FALLTHROUGH;
138 case DW_TAG_structure_type:
139 case DW_TAG_class_type:
140 case DW_TAG_union_type:
141 case DW_TAG_array_type:
142 *locp = loc_aggregate;
143 return nloc_aggregate;
144 }
145
146 /* XXX We don't have a good way to return specific errors from ebl calls.
147 This value means we do not understand the type, but it is well-formed
148 DWARF and might be valid. */
149 return -2;
150 }
151