1 /* Function return value location for ARM EABI.
2 Copyright (C) 2009-2010, 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 arm_
37 #include "libebl_CPU.h"
38
39
40 /* r0, or pair r0, r1, or aggregate up to r0-r3. */
41 static const Dwarf_Op loc_intreg[] =
42 {
43 { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 4 },
44 { .atom = DW_OP_reg1 }, { .atom = DW_OP_piece, .number = 4 },
45 { .atom = DW_OP_reg2 }, { .atom = DW_OP_piece, .number = 4 },
46 { .atom = DW_OP_reg3 }, { .atom = DW_OP_piece, .number = 4 },
47 };
48 #define nloc_intreg 1
49 #define nloc_intregs(n) (2 * (n))
50
51 /* The return value is a structure and is actually stored in stack space
52 passed in a hidden argument by the caller. But, the compiler
53 helpfully returns the address of that space in r0. */
54 static const Dwarf_Op loc_aggregate[] =
55 {
56 { .atom = DW_OP_breg0, .number = 0 }
57 };
58 #define nloc_aggregate 1
59
60
61 int
arm_return_value_location(Dwarf_Die * functypedie,const Dwarf_Op ** locp)62 arm_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
63 {
64 /* Start with the function's type, and get the DW_AT_type attribute,
65 which is the type of the return value. */
66 Dwarf_Die die_mem, *typedie = &die_mem;
67 int tag = dwarf_peeled_die_type (functypedie, typedie);
68 if (tag <= 0)
69 return tag;
70
71 Dwarf_Word size;
72 switch (tag)
73 {
74 case -1:
75 return -1;
76
77 case DW_TAG_subrange_type:
78 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
79 {
80 Dwarf_Attribute attr_mem, *attr;
81 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
82 typedie = dwarf_formref_die (attr, &die_mem);
83 tag = DWARF_TAG_OR_RETURN (typedie);
84 }
85 /* Fall through. */
86
87 case DW_TAG_base_type:
88 case DW_TAG_enumeration_type:
89 case DW_TAG_pointer_type:
90 case DW_TAG_ptr_to_member_type:
91 {
92 Dwarf_Attribute attr_mem;
93 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
94 &attr_mem), &size) != 0)
95 {
96 if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
97 size = 4;
98 else
99 return -1;
100 }
101 if (size <= 16)
102 {
103 intreg:
104 *locp = loc_intreg;
105 return size <= 4 ? nloc_intreg : nloc_intregs ((size + 3) / 4);
106 }
107
108 aggregate:
109 *locp = loc_aggregate;
110 return nloc_aggregate;
111 }
112
113 case DW_TAG_structure_type:
114 case DW_TAG_class_type:
115 case DW_TAG_union_type:
116 case DW_TAG_array_type:
117 if (dwarf_aggregate_size (typedie, &size) == 0
118 && size > 0 && size <= 4)
119 goto intreg;
120 goto aggregate;
121 }
122
123 /* XXX We don't have a good way to return specific errors from ebl calls.
124 This value means we do not understand the type, but it is well-formed
125 DWARF and might be valid. */
126 return -2;
127 }
128