1 /* Function return value location for Alpha ELF ABI.
2 Copyright (C) 2005, 2007, 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 alpha_
37 #include "libebl_CPU.h"
38
39
40 /* $0. */
41 static const Dwarf_Op loc_intreg[] =
42 {
43 { .atom = DW_OP_reg0 }
44 };
45 #define nloc_intreg 1
46
47 /* $f0, or pair $f0, $f1. */
48 static const Dwarf_Op loc_fpreg[] =
49 {
50 { .atom = DW_OP_regx, .number = 32 }, { .atom = DW_OP_piece, .number = 4 },
51 { .atom = DW_OP_regx, .number = 33 }, { .atom = DW_OP_piece, .number = 4 },
52 };
53 #define nloc_fpreg 1
54 #define nloc_fpregpair 4
55
56 /* The return value is a structure and is actually stored in stack space
57 passed in a hidden argument by the caller. But, the compiler
58 helpfully returns the address of that space in $0. */
59 static const Dwarf_Op loc_aggregate[] =
60 {
61 { .atom = DW_OP_breg0, .number = 0 }
62 };
63 #define nloc_aggregate 1
64
65 int
alpha_return_value_location(Dwarf_Die * functypedie,const Dwarf_Op ** locp)66 alpha_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
67 {
68 /* Start with the function's type, and get the DW_AT_type attribute,
69 which is the type of the return value. */
70 Dwarf_Die die_mem, *typedie = &die_mem;
71 int tag = dwarf_peeled_die_type (functypedie, typedie);
72 if (tag <= 0)
73 return tag;
74
75 switch (tag)
76 {
77 case -1:
78 return -1;
79
80 case DW_TAG_subrange_type:
81 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
82 {
83 Dwarf_Attribute attr_mem, *attr;
84 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
85 typedie = dwarf_formref_die (attr, &die_mem);
86 tag = DWARF_TAG_OR_RETURN (typedie);
87 }
88 FALLTHROUGH;
89
90 case DW_TAG_base_type:
91 case DW_TAG_enumeration_type:
92 CASE_POINTER:
93 {
94 Dwarf_Attribute attr_mem;
95 Dwarf_Word size;
96 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
97 &attr_mem), &size) != 0)
98 {
99 if (dwarf_is_pointer (tag))
100 size = 8;
101 else
102 return -1;
103 }
104 if (tag == DW_TAG_base_type)
105 {
106 Dwarf_Word encoding;
107 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
108 &attr_mem),
109 &encoding) != 0)
110 return -1;
111
112 *locp = loc_fpreg;
113 if (encoding == DW_ATE_float)
114 {
115 if (size <= 8)
116 return nloc_fpreg;
117 goto aggregate;
118 }
119 if (encoding == DW_ATE_complex_float)
120 {
121 if (size <= 8 * 2)
122 return nloc_fpregpair;
123 goto aggregate;
124 }
125 }
126 if (size <= 8)
127 {
128 *locp = loc_intreg;
129 return nloc_intreg;
130 }
131 }
132
133 FALLTHROUGH;
134
135 case DW_TAG_structure_type:
136 case DW_TAG_class_type:
137 case DW_TAG_union_type:
138 case DW_TAG_string_type:
139 case DW_TAG_array_type:
140 aggregate:
141 *locp = loc_aggregate;
142 return nloc_aggregate;
143 }
144
145 /* XXX We don't have a good way to return specific errors from ebl calls.
146 This value means we do not understand the type, but it is well-formed
147 DWARF and might be valid. */
148 return -2;
149 }
150