1 /* Function return value location for Linux/PPC ABI.
2 Copyright (C) 2005, 2006, 2007, 2010, 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 ppc_
37 #include "libebl_CPU.h"
38
39
40 /* This is the SVR4 ELF ABI convention, but AIX and Linux do not use it. */
41 #define SVR4_STRUCT_RETURN 0
42
43
44 /* r3, or pair r3, r4, or quad r3-r6. */
45 static const Dwarf_Op loc_intreg[] =
46 {
47 { .atom = DW_OP_reg3 }, { .atom = DW_OP_piece, .number = 4 },
48 { .atom = DW_OP_reg4 }, { .atom = DW_OP_piece, .number = 4 },
49 { .atom = DW_OP_reg5 }, { .atom = DW_OP_piece, .number = 4 },
50 { .atom = DW_OP_reg6 }, { .atom = DW_OP_piece, .number = 4 },
51 };
52 #define nloc_intreg 1
53 #define nloc_intregpair 4
54 #define nloc_intregquad 8
55
56 /* f1. */
57 static const Dwarf_Op loc_fpreg[] =
58 {
59 { .atom = DW_OP_regx, .number = 33 }
60 };
61 #define nloc_fpreg 1
62
63 /* vr2. */
64 static const Dwarf_Op loc_vmxreg[] =
65 {
66 { .atom = DW_OP_regx, .number = 1124 + 2 }
67 };
68 #define nloc_vmxreg 1
69
70 /* The return value is a structure and is actually stored in stack space
71 passed in a hidden argument by the caller. But, the compiler
72 helpfully returns the address of that space in r3. */
73 static const Dwarf_Op loc_aggregate[] =
74 {
75 { .atom = DW_OP_breg3, .number = 0 }
76 };
77 #define nloc_aggregate 1
78
79
80 /* XXX We should check the SHT_GNU_ATTRIBUTES bits here (or in ppc_init). */
81 static bool
ppc_altivec_abi(void)82 ppc_altivec_abi (void)
83 {
84 return true;
85 }
86
87 int
ppc_return_value_location(Dwarf_Die * functypedie,const Dwarf_Op ** locp)88 ppc_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
89 {
90 /* Start with the function's type, and get the DW_AT_type attribute,
91 which is the type of the return value. */
92 Dwarf_Die die_mem, *typedie = &die_mem;
93 int tag = dwarf_peeled_die_type (functypedie, typedie);
94 if (tag <= 0)
95 return tag;
96
97 Dwarf_Word size;
98 switch (tag)
99 {
100 case -1:
101 return -1;
102
103 case DW_TAG_subrange_type:
104 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
105 {
106 Dwarf_Attribute attr_mem, *attr;
107 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
108 typedie = dwarf_formref_die (attr, &die_mem);
109 tag = DWARF_TAG_OR_RETURN (typedie);
110 }
111 FALLTHROUGH;
112
113 case DW_TAG_base_type:
114 case DW_TAG_enumeration_type:
115 CASE_POINTER:
116 {
117 Dwarf_Attribute attr_mem;
118 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
119 &attr_mem), &size) != 0)
120 {
121 if (dwarf_is_pointer (tag))
122 size = 4;
123 else
124 return -1;
125 }
126 }
127
128 if (size <= 8)
129 {
130 if (tag == DW_TAG_base_type)
131 {
132 Dwarf_Attribute attr_mem;
133 Dwarf_Word encoding;
134 if (dwarf_formudata (dwarf_attr_integrate (typedie,
135 DW_AT_encoding,
136 &attr_mem),
137 &encoding) != 0)
138 return -1;
139 if (encoding == DW_ATE_float)
140 {
141 *locp = loc_fpreg;
142 return nloc_fpreg;
143 }
144 }
145 intreg:
146 *locp = loc_intreg;
147 return size <= 4 ? nloc_intreg : nloc_intregpair;
148 }
149
150 aggregate:
151 *locp = loc_aggregate;
152 return nloc_aggregate;
153
154 case DW_TAG_array_type:
155 {
156 Dwarf_Attribute attr_mem;
157 bool is_vector;
158 if (dwarf_formflag (dwarf_attr_integrate (typedie, DW_AT_GNU_vector,
159 &attr_mem), &is_vector) == 0
160 && is_vector
161 && dwarf_aggregate_size (typedie, &size) == 0)
162 switch (size)
163 {
164 case 16:
165 if (ppc_altivec_abi ())
166 {
167 *locp = loc_vmxreg;
168 return nloc_vmxreg;
169 }
170 *locp = loc_intreg;
171 return nloc_intregquad;
172 }
173 }
174 FALLTHROUGH;
175
176 case DW_TAG_structure_type:
177 case DW_TAG_class_type:
178 case DW_TAG_union_type:
179 if (SVR4_STRUCT_RETURN
180 && dwarf_aggregate_size (typedie, &size) == 0
181 && size > 0 && size <= 8)
182 goto intreg;
183 goto aggregate;
184 }
185
186 /* XXX We don't have a good way to return specific errors from ebl calls.
187 This value means we do not understand the type, but it is well-formed
188 DWARF and might be valid. */
189 return -2;
190 }
191