1 /* Function return value location for S/390 ABI.
2 Copyright (C) 2006, 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 s390_
37 #include "libebl_CPU.h"
38
39
40 /* %r2, or pair %r2, %r3. */
41 static const Dwarf_Op loc_intreg[] =
42 {
43 { .atom = DW_OP_reg2 }, { .atom = DW_OP_piece, .number = 4 },
44 { .atom = DW_OP_reg3 }, { .atom = DW_OP_piece, .number = 4 },
45 };
46 #define nloc_intreg 1
47 #define nloc_intregpair 4
48
49 /* %f0. */
50 static const Dwarf_Op loc_fpreg[] =
51 {
52 { .atom = DW_OP_reg16 },
53 };
54 #define nloc_fpreg 1
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 %r2. */
59 static const Dwarf_Op loc_aggregate[] =
60 {
61 { .atom = DW_OP_breg2, .number = 0 }
62 };
63 #define nloc_aggregate 1
64
65
66 int
s390_return_value_location(Dwarf_Die * functypedie,const Dwarf_Op ** locp)67 s390_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
68 {
69 /* Start with the function's type, and get the DW_AT_type attribute,
70 which is the type of the return value. */
71 Dwarf_Die die_mem, *typedie = &die_mem;
72 int tag = dwarf_peeled_die_type (functypedie, typedie);
73 if (tag <= 0)
74 return tag;
75
76 Dwarf_Word size;
77 switch (tag)
78 {
79 case -1:
80 return -1;
81
82 case DW_TAG_subrange_type:
83 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
84 {
85 Dwarf_Attribute attr_mem, *attr;
86 attr = dwarf_attr (typedie, DW_AT_type, &attr_mem);
87 typedie = dwarf_formref_die (attr, &die_mem);
88 tag = DWARF_TAG_OR_RETURN (typedie);
89 }
90 FALLTHROUGH;
91
92 case DW_TAG_base_type:
93 case DW_TAG_enumeration_type:
94 CASE_POINTER:
95 {
96 Dwarf_Die cudie;
97 uint8_t asize;
98 if (dwarf_diecu (typedie, &cudie, &asize, NULL) == NULL)
99 return -1;
100
101 Dwarf_Attribute attr_mem;
102 if (dwarf_formudata (dwarf_attr (typedie, DW_AT_byte_size,
103 &attr_mem), &size) != 0)
104 {
105 if (dwarf_is_pointer (tag))
106 size = asize;
107 else
108 return -1;
109 }
110 if (tag == DW_TAG_base_type)
111 {
112 Dwarf_Word encoding;
113 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
114 &attr_mem),
115 &encoding) != 0)
116 return -1;
117 if (encoding == DW_ATE_float && size <= 8)
118 {
119 *locp = loc_fpreg;
120 return nloc_fpreg;
121 }
122 }
123 if (size <= 8)
124 {
125 *locp = loc_intreg;
126 return size <= asize ? nloc_intreg : nloc_intregpair;
127 }
128 }
129 FALLTHROUGH;
130
131 case DW_TAG_structure_type:
132 case DW_TAG_class_type:
133 case DW_TAG_union_type:
134 case DW_TAG_array_type:
135 *locp = loc_aggregate;
136 return nloc_aggregate;
137 }
138
139 /* XXX We don't have a good way to return specific errors from ebl calls.
140 This value means we do not understand the type, but it is well-formed
141 DWARF and might be valid. */
142 return -2;
143 }
144