1 /* Function return value location for Linux/x86-64 ABI.
2 Copyright (C) 2005-2010 Red Hat, Inc.
3 This file is part of Red Hat elfutils.
5 Red Hat elfutils is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by the
7 Free Software Foundation; version 2 of the License.
9 Red Hat elfutils is distributed in the hope that it will be useful, but
10 WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 General Public License for more details.
14 You should have received a copy of the GNU General Public License along
15 with Red Hat elfutils; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
18 Red Hat elfutils is an included package of the Open Invention Network.
19 An included package of the Open Invention Network is a package for which
20 Open Invention Network licensees cross-license their patents. No patent
21 license is granted, either expressly or impliedly, by designation as an
22 included package. Should you wish to participate in the Open Invention
23 Network licensing program, please visit www.openinventionnetwork.com
24 <http://www.openinventionnetwork.com>. */
33 #define BACKEND x86_64_
34 #include "libebl_CPU.h"
37 /* %rax, or pair %rax, %rdx. */
38 static const Dwarf_Op loc_intreg[] =
40 { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 8 },
41 { .atom = DW_OP_reg1 }, { .atom = DW_OP_piece, .number = 8 },
44 #define nloc_intregpair 4
46 /* %st(0), or pair %st(0), %st(1). */
47 static const Dwarf_Op loc_x87reg[] =
49 { .atom = DW_OP_regx, .number = 33 },
50 { .atom = DW_OP_piece, .number = 10 },
51 { .atom = DW_OP_regx, .number = 34 },
52 { .atom = DW_OP_piece, .number = 10 },
55 #define nloc_x87regpair 4
57 /* %xmm0, or pair %xmm0, %xmm1. */
58 static const Dwarf_Op loc_ssereg[] =
60 { .atom = DW_OP_reg17 }, { .atom = DW_OP_piece, .number = 16 },
61 { .atom = DW_OP_reg18 }, { .atom = DW_OP_piece, .number = 16 },
64 #define nloc_sseregpair 4
66 /* The return value is a structure and is actually stored in stack space
67 passed in a hidden argument by the caller. But, the compiler
68 helpfully returns the address of that space in %rax. */
69 static const Dwarf_Op loc_aggregate[] =
71 { .atom = DW_OP_breg0, .number = 0 }
73 #define nloc_aggregate 1
77 x86_64_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
79 /* Start with the function's type, and get the DW_AT_type attribute,
80 which is the type of the return value. */
82 Dwarf_Attribute attr_mem;
83 Dwarf_Attribute *attr = dwarf_attr_integrate (functypedie, DW_AT_type,
86 /* The function has no return value, like a `void' function in C. */
90 Dwarf_Die *typedie = dwarf_formref_die (attr, &die_mem);
91 int tag = dwarf_tag (typedie);
93 /* Follow typedefs and qualifiers to get to the actual type. */
94 while (tag == DW_TAG_typedef
95 || tag == DW_TAG_const_type || tag == DW_TAG_volatile_type
96 || tag == DW_TAG_restrict_type || tag == DW_TAG_mutable_type)
98 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
99 typedie = dwarf_formref_die (attr, &die_mem);
100 tag = dwarf_tag (typedie);
109 case DW_TAG_subrange_type:
110 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
112 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
113 typedie = dwarf_formref_die (attr, &die_mem);
114 tag = dwarf_tag (typedie);
118 case DW_TAG_base_type:
119 case DW_TAG_enumeration_type:
120 case DW_TAG_pointer_type:
121 case DW_TAG_ptr_to_member_type:
122 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
123 &attr_mem), &size) != 0)
125 if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
130 if (tag == DW_TAG_base_type)
133 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
140 case DW_ATE_complex_float:
143 case 4 * 2: /* complex float */
144 case 8 * 2: /* complex double */
146 return nloc_sseregpair;
147 case 16 * 2: /* complex long double */
149 return nloc_x87regpair;
160 case 16: /* long double */
161 /* XXX distinguish __float128, which is sseregpair?? */
174 return nloc_intregpair;
177 *locp = loc_aggregate;
178 return nloc_aggregate;
180 case DW_TAG_structure_type:
181 case DW_TAG_class_type:
182 case DW_TAG_union_type:
183 case DW_TAG_array_type:
184 if (dwarf_aggregate_size (typedie, &size) != 0)
190 Must examine the fields in picayune ways to determine the
191 actual answer. This will be right for small C structs
192 containing integer types and similarly simple cases.
198 /* XXX We don't have a good way to return specific errors from ebl calls.
199 This value means we do not understand the type, but it is well-formed
200 DWARF and might be valid. */