1 /* Function return value location for S/390 ABI.
2 Copyright (C) 2006, 2007 Red Hat, Inc.
3 This file is part of Red Hat elfutils.
4
5 Red Hat elfutils is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by the
7 Free Software Foundation; version 2 of the License.
8
9 Red Hat elfutils is distributed in the hope that it will be useful, but
10 WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 General Public License for more details.
13
14 You should have received a copy of the GNU General Public License along
15 with Red Hat elfutils; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
17
18 Red Hat elfutils is an included package of the Open Invention Network.
19 An included package of the Open Invention Network is a package for which
20 Open Invention Network licensees cross-license their patents. No patent
21 license is granted, either expressly or impliedly, by designation as an
22 included package. Should you wish to participate in the Open Invention
23 Network licensing program, please visit www.openinventionnetwork.com
24 <http://www.openinventionnetwork.com>. */
25
26 #ifdef HAVE_CONFIG_H
27 # include <config.h>
28 #endif
29
30 #include <assert.h>
31 #include <dwarf.h>
32
33 #define BACKEND s390_
34 #include "libebl_CPU.h"
35
36
37 /* %r2, or pair %r2, %r3. */
38 static const Dwarf_Op loc_intreg[] =
39 {
40 { .atom = DW_OP_reg2 }, { .atom = DW_OP_piece, .number = 4 },
41 { .atom = DW_OP_reg3 }, { .atom = DW_OP_piece, .number = 4 },
42 };
43 #define nloc_intreg 1
44 #define nloc_intregpair 4
45
46 /* %f0. */
47 static const Dwarf_Op loc_fpreg[] =
48 {
49 { .atom = DW_OP_reg16 },
50 };
51 #define nloc_fpreg 1
52
53 /* The return value is a structure and is actually stored in stack space
54 passed in a hidden argument by the caller. But, the compiler
55 helpfully returns the address of that space in %r2. */
56 static const Dwarf_Op loc_aggregate[] =
57 {
58 { .atom = DW_OP_breg2, .number = 0 }
59 };
60 #define nloc_aggregate 1
61
62
63 int
s390_return_value_location(Dwarf_Die * functypedie,const Dwarf_Op ** locp)64 s390_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
69 Dwarf_Attribute attr_mem;
70 Dwarf_Attribute *attr = dwarf_attr_integrate (functypedie, DW_AT_type,
71 &attr_mem);
72 if (attr == NULL)
73 /* The function has no return value, like a `void' function in C. */
74 return 0;
75
76 Dwarf_Die die_mem;
77 Dwarf_Die *typedie = dwarf_formref_die (attr, &die_mem);
78 int tag = dwarf_tag (typedie);
79
80 /* Follow typedefs and qualifiers to get to the actual type. */
81 while (tag == DW_TAG_typedef
82 || tag == DW_TAG_const_type || tag == DW_TAG_volatile_type
83 || tag == DW_TAG_restrict_type || tag == DW_TAG_mutable_type)
84 {
85 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
86 typedie = dwarf_formref_die (attr, &die_mem);
87 tag = dwarf_tag (typedie);
88 }
89
90 Dwarf_Word size;
91 switch (tag)
92 {
93 case -1:
94 return -1;
95
96 case DW_TAG_subrange_type:
97 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
98 {
99 attr = dwarf_attr (typedie, DW_AT_type, &attr_mem);
100 typedie = dwarf_formref_die (attr, &die_mem);
101 tag = dwarf_tag (typedie);
102 }
103 /* Fall through. */
104
105 case DW_TAG_base_type:
106 case DW_TAG_enumeration_type:
107 case DW_TAG_pointer_type:
108 case DW_TAG_ptr_to_member_type:
109 {
110 Dwarf_Die cudie;
111 uint8_t asize;
112 if (dwarf_diecu (typedie, &cudie, &asize, NULL) == NULL)
113 return -1;
114
115 if (dwarf_formudata (dwarf_attr (typedie, DW_AT_byte_size,
116 &attr_mem), &size) != 0)
117 {
118 if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
119 size = asize;
120 else
121 return -1;
122 }
123 if (tag == DW_TAG_base_type)
124 {
125 Dwarf_Word encoding;
126 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
127 &attr_mem),
128 &encoding) != 0)
129 return -1;
130 if (encoding == DW_ATE_float && size <= 8)
131 {
132 *locp = loc_fpreg;
133 return nloc_fpreg;
134 }
135 }
136 if (size <= 8)
137 {
138 *locp = loc_intreg;
139 return size <= asize ? nloc_intreg : nloc_intregpair;
140 }
141 }
142 /* Fall through. */
143
144 case DW_TAG_structure_type:
145 case DW_TAG_class_type:
146 case DW_TAG_union_type:
147 case DW_TAG_array_type:
148 *locp = loc_aggregate;
149 return nloc_aggregate;
150 }
151
152 /* XXX We don't have a good way to return specific errors from ebl calls.
153 This value means we do not understand the type, but it is well-formed
154 DWARF and might be valid. */
155 return -2;
156 }
157