Line data Source code
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
82 : ppc_altivec_abi (void)
83 : {
84 0 : return true;
85 : }
86 :
87 : int
88 0 : 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 0 : Dwarf_Die die_mem, *typedie = &die_mem;
93 0 : int tag = dwarf_peeled_die_type (functypedie, typedie);
94 0 : if (tag <= 0)
95 : return tag;
96 :
97 0 : Dwarf_Word size;
98 0 : switch (tag)
99 : {
100 : case -1:
101 : return -1;
102 :
103 0 : case DW_TAG_subrange_type:
104 0 : if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
105 : {
106 0 : Dwarf_Attribute attr_mem, *attr;
107 0 : attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
108 0 : typedie = dwarf_formref_die (attr, &die_mem);
109 0 : tag = DWARF_TAG_OR_RETURN (typedie);
110 : }
111 0 : FALLTHROUGH;
112 :
113 : case DW_TAG_base_type:
114 : case DW_TAG_enumeration_type:
115 : case DW_TAG_pointer_type:
116 : case DW_TAG_ptr_to_member_type:
117 0 : {
118 0 : Dwarf_Attribute attr_mem;
119 0 : if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
120 : &attr_mem), &size) != 0)
121 : {
122 0 : if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
123 0 : size = 4;
124 : else
125 0 : return -1;
126 : }
127 : }
128 :
129 0 : if (size <= 8)
130 : {
131 0 : if (tag == DW_TAG_base_type)
132 : {
133 0 : Dwarf_Attribute attr_mem;
134 0 : Dwarf_Word encoding;
135 0 : if (dwarf_formudata (dwarf_attr_integrate (typedie,
136 : DW_AT_encoding,
137 : &attr_mem),
138 : &encoding) != 0)
139 0 : return -1;
140 0 : if (encoding == DW_ATE_float)
141 : {
142 0 : *locp = loc_fpreg;
143 0 : return nloc_fpreg;
144 : }
145 : }
146 0 : intreg:
147 0 : *locp = loc_intreg;
148 0 : return size <= 4 ? nloc_intreg : nloc_intregpair;
149 : }
150 :
151 0 : aggregate:
152 0 : *locp = loc_aggregate;
153 0 : return nloc_aggregate;
154 :
155 0 : case DW_TAG_array_type:
156 0 : {
157 0 : Dwarf_Attribute attr_mem;
158 0 : bool is_vector;
159 0 : if (dwarf_formflag (dwarf_attr_integrate (typedie, DW_AT_GNU_vector,
160 : &attr_mem), &is_vector) == 0
161 0 : && is_vector
162 0 : && dwarf_aggregate_size (typedie, &size) == 0)
163 0 : switch (size)
164 : {
165 : case 16:
166 0 : if (ppc_altivec_abi ())
167 : {
168 0 : *locp = loc_vmxreg;
169 0 : return nloc_vmxreg;
170 : }
171 : *locp = loc_intreg;
172 : return nloc_intregquad;
173 : }
174 : }
175 0 : FALLTHROUGH;
176 :
177 : case DW_TAG_structure_type:
178 : case DW_TAG_class_type:
179 : case DW_TAG_union_type:
180 0 : if (SVR4_STRUCT_RETURN
181 : && dwarf_aggregate_size (typedie, &size) == 0
182 : && size > 0 && size <= 8)
183 : goto intreg;
184 0 : goto aggregate;
185 : }
186 :
187 : /* XXX We don't have a good way to return specific errors from ebl calls.
188 : This value means we do not understand the type, but it is well-formed
189 : DWARF and might be valid. */
190 0 : return -2;
191 : }
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