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 /* Fall through. */
89
90 case DW_TAG_base_type:
91 case DW_TAG_enumeration_type:
92 case DW_TAG_pointer_type:
93 case DW_TAG_ptr_to_member_type:
94 {
95 Dwarf_Attribute attr_mem;
96 Dwarf_Word size;
97 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
98 &attr_mem), &size) != 0)
99 {
100 if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
101 size = 8;
102 else
103 return -1;
104 }
105 if (tag == DW_TAG_base_type)
106 {
107 Dwarf_Word encoding;
108 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
109 &attr_mem),
110 &encoding) != 0)
111 return -1;
112
113 *locp = loc_fpreg;
114 if (encoding == DW_ATE_float)
115 {
116 if (size <= 8)
117 return nloc_fpreg;
118 goto aggregate;
119 }
120 if (encoding == DW_ATE_complex_float)
121 {
122 if (size <= 8 * 2)
123 return nloc_fpregpair;
124 goto aggregate;
125 }
126 }
127 if (size <= 8)
128 {
129 *locp = loc_intreg;
130 return nloc_intreg;
131 }
132 }
133
134 /* Else fall through. */
135
136 case DW_TAG_structure_type:
137 case DW_TAG_class_type:
138 case DW_TAG_union_type:
139 case DW_TAG_string_type:
140 case DW_TAG_array_type:
141 aggregate:
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