Branch data Line data Source code
1 : : /* Function return value location for Linux/i386 ABI.
2 : : Copyright (C) 2005-2010, 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 i386_
37 : : #include "libebl_CPU.h"
38 : :
39 : :
40 : : /* %eax, or pair %eax, %edx. */
41 : : static const Dwarf_Op loc_intreg[] =
42 : : {
43 : : { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 4 },
44 : : { .atom = DW_OP_reg2 }, { .atom = DW_OP_piece, .number = 4 },
45 : : };
46 : : #define nloc_intreg 1
47 : : #define nloc_intregpair 4
48 : :
49 : : /* %st(0). */
50 : : static const Dwarf_Op loc_fpreg[] =
51 : : {
52 : : { .atom = DW_OP_reg11 }
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 %eax. */
59 : : static const Dwarf_Op loc_aggregate[] =
60 : : {
61 : : { .atom = DW_OP_breg0, .number = 0 }
62 : : };
63 : : #define nloc_aggregate 1
64 : :
65 : : int
66 : 0 : i386_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 : 0 : Dwarf_Die die_mem, *typedie = &die_mem;
71 : 0 : int tag = dwarf_peeled_die_type (functypedie, typedie);
72 [ # # ]: 0 : if (tag <= 0)
73 : : return tag;
74 : :
75 [ # # # # : 0 : switch (tag)
# ]
76 : : {
77 : : case -1:
78 : : return -1;
79 : :
80 : 0 : case DW_TAG_subrange_type:
81 [ # # ]: 0 : if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
82 : : {
83 : 0 : Dwarf_Attribute attr_mem, *attr;
84 : 0 : attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
85 : 0 : typedie = dwarf_formref_die (attr, &die_mem);
86 [ # # ]: 0 : tag = DWARF_TAG_OR_RETURN (typedie);
87 : : }
88 : 0 : FALLTHROUGH;
89 : :
90 : : case DW_TAG_base_type:
91 : : case DW_TAG_enumeration_type:
92 : : CASE_POINTER:
93 : : {
94 : 0 : Dwarf_Word size;
95 : 0 : Dwarf_Attribute attr_mem;
96 [ # # ]: 0 : if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
97 : : &attr_mem), &size) != 0)
98 : : {
99 [ # # ]: 0 : if (dwarf_is_pointer (tag))
100 : 0 : size = 4;
101 : : else
102 : 0 : return -1;
103 : : }
104 [ # # ]: 0 : if (tag == DW_TAG_base_type)
105 : : {
106 : 0 : Dwarf_Word encoding;
107 [ # # ]: 0 : if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
108 : : &attr_mem),
109 : : &encoding) != 0)
110 : 0 : return -1;
111 [ # # ]: 0 : if (encoding == DW_ATE_float)
112 : : {
113 [ # # ]: 0 : if (size > 16)
114 : : return -2;
115 : 0 : *locp = loc_fpreg;
116 : 0 : return nloc_fpreg;
117 : : }
118 : : }
119 : 0 : *locp = loc_intreg;
120 [ # # ]: 0 : if (size <= 4)
121 : : return nloc_intreg;
122 [ # # ]: 0 : if (size <= 8)
123 : : return nloc_intregpair;
124 : : }
125 : 0 : FALLTHROUGH;
126 : :
127 : : case DW_TAG_structure_type:
128 : : case DW_TAG_class_type:
129 : : case DW_TAG_union_type:
130 : : case DW_TAG_array_type:
131 : 0 : *locp = loc_aggregate;
132 : 0 : return nloc_aggregate;
133 : : }
134 : :
135 : : /* XXX We don't have a good way to return specific errors from ebl calls.
136 : : This value means we do not understand the type, but it is well-formed
137 : : DWARF and might be valid. */
138 : 0 : return -2;
139 : : }
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