Ben Cheng | 25b3c04 | 2013-11-20 14:45:36 -0800 | [diff] [blame] | 1 | /* Function return value location for Linux/x86-64 ABI. |
Elliott Hughes | 0333382 | 2015-02-18 22:19:45 -0800 | [diff] [blame^] | 2 | Copyright (C) 2005-2010, 2014 Red Hat, Inc. |
| 3 | This file is part of elfutils. |
Ben Cheng | 25b3c04 | 2013-11-20 14:45:36 -0800 | [diff] [blame] | 4 | |
Elliott Hughes | 0333382 | 2015-02-18 22:19:45 -0800 | [diff] [blame^] | 5 | This file is free software; you can redistribute it and/or modify |
| 6 | it under the terms of either |
Ben Cheng | 25b3c04 | 2013-11-20 14:45:36 -0800 | [diff] [blame] | 7 | |
Elliott Hughes | 0333382 | 2015-02-18 22:19:45 -0800 | [diff] [blame^] | 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 |
Ben Cheng | 25b3c04 | 2013-11-20 14:45:36 -0800 | [diff] [blame] | 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 | |
Elliott Hughes | 0333382 | 2015-02-18 22:19:45 -0800 | [diff] [blame^] | 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/>. */ |
Ben Cheng | 25b3c04 | 2013-11-20 14:45:36 -0800 | [diff] [blame] | 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 x86_64_ |
| 37 | #include "libebl_CPU.h" |
| 38 | |
| 39 | |
| 40 | /* %rax, or pair %rax, %rdx. */ |
| 41 | static const Dwarf_Op loc_intreg[] = |
| 42 | { |
| 43 | { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 8 }, |
| 44 | { .atom = DW_OP_reg1 }, { .atom = DW_OP_piece, .number = 8 }, |
| 45 | }; |
| 46 | #define nloc_intreg 1 |
| 47 | #define nloc_intregpair 4 |
| 48 | |
| 49 | /* %st(0), or pair %st(0), %st(1). */ |
| 50 | static const Dwarf_Op loc_x87reg[] = |
| 51 | { |
| 52 | { .atom = DW_OP_regx, .number = 33 }, |
| 53 | { .atom = DW_OP_piece, .number = 10 }, |
| 54 | { .atom = DW_OP_regx, .number = 34 }, |
| 55 | { .atom = DW_OP_piece, .number = 10 }, |
| 56 | }; |
| 57 | #define nloc_x87reg 1 |
| 58 | #define nloc_x87regpair 4 |
| 59 | |
| 60 | /* %xmm0, or pair %xmm0, %xmm1. */ |
| 61 | static const Dwarf_Op loc_ssereg[] = |
| 62 | { |
| 63 | { .atom = DW_OP_reg17 }, { .atom = DW_OP_piece, .number = 16 }, |
| 64 | { .atom = DW_OP_reg18 }, { .atom = DW_OP_piece, .number = 16 }, |
| 65 | }; |
| 66 | #define nloc_ssereg 1 |
| 67 | #define nloc_sseregpair 4 |
| 68 | |
| 69 | /* The return value is a structure and is actually stored in stack space |
| 70 | passed in a hidden argument by the caller. But, the compiler |
| 71 | helpfully returns the address of that space in %rax. */ |
| 72 | static const Dwarf_Op loc_aggregate[] = |
| 73 | { |
| 74 | { .atom = DW_OP_breg0, .number = 0 } |
| 75 | }; |
| 76 | #define nloc_aggregate 1 |
| 77 | |
| 78 | |
| 79 | int |
| 80 | x86_64_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp) |
| 81 | { |
| 82 | /* Start with the function's type, and get the DW_AT_type attribute, |
| 83 | which is the type of the return value. */ |
Elliott Hughes | 0333382 | 2015-02-18 22:19:45 -0800 | [diff] [blame^] | 84 | Dwarf_Die die_mem, *typedie = &die_mem; |
| 85 | int tag = dwarf_peeled_die_type (functypedie, typedie); |
| 86 | if (tag <= 0) |
| 87 | return tag; |
Ben Cheng | 25b3c04 | 2013-11-20 14:45:36 -0800 | [diff] [blame] | 88 | |
| 89 | Dwarf_Word size; |
| 90 | switch (tag) |
| 91 | { |
| 92 | case -1: |
| 93 | return -1; |
| 94 | |
| 95 | case DW_TAG_subrange_type: |
| 96 | if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size)) |
| 97 | { |
Elliott Hughes | 0333382 | 2015-02-18 22:19:45 -0800 | [diff] [blame^] | 98 | Dwarf_Attribute attr_mem, *attr; |
Ben Cheng | 25b3c04 | 2013-11-20 14:45:36 -0800 | [diff] [blame] | 99 | attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); |
| 100 | typedie = dwarf_formref_die (attr, &die_mem); |
Elliott Hughes | 0333382 | 2015-02-18 22:19:45 -0800 | [diff] [blame^] | 101 | tag = DWARF_TAG_OR_RETURN (typedie); |
Ben Cheng | 25b3c04 | 2013-11-20 14:45:36 -0800 | [diff] [blame] | 102 | } |
| 103 | /* Fall through. */ |
| 104 | |
| 105 | case DW_TAG_base_type: |
| 106 | case DW_TAG_enumeration_type: |
| 107 | case DW_TAG_pointer_type: |
| 108 | case DW_TAG_ptr_to_member_type: |
Elliott Hughes | 0333382 | 2015-02-18 22:19:45 -0800 | [diff] [blame^] | 109 | { |
| 110 | Dwarf_Attribute attr_mem; |
| 111 | if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size, |
| 112 | &attr_mem), &size) != 0) |
| 113 | { |
| 114 | if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) |
| 115 | size = 8; |
| 116 | else |
| 117 | return -1; |
| 118 | } |
| 119 | } |
| 120 | |
Ben Cheng | 25b3c04 | 2013-11-20 14:45:36 -0800 | [diff] [blame] | 121 | if (tag == DW_TAG_base_type) |
| 122 | { |
Elliott Hughes | 0333382 | 2015-02-18 22:19:45 -0800 | [diff] [blame^] | 123 | Dwarf_Attribute attr_mem; |
Ben Cheng | 25b3c04 | 2013-11-20 14:45:36 -0800 | [diff] [blame] | 124 | Dwarf_Word encoding; |
| 125 | if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding, |
| 126 | &attr_mem), |
| 127 | &encoding) != 0) |
| 128 | return -1; |
| 129 | |
| 130 | switch (encoding) |
| 131 | { |
| 132 | case DW_ATE_complex_float: |
| 133 | switch (size) |
| 134 | { |
| 135 | case 4 * 2: /* complex float */ |
| 136 | case 8 * 2: /* complex double */ |
| 137 | *locp = loc_ssereg; |
| 138 | return nloc_sseregpair; |
| 139 | case 16 * 2: /* complex long double */ |
| 140 | *locp = loc_x87reg; |
| 141 | return nloc_x87regpair; |
| 142 | } |
| 143 | return -2; |
| 144 | |
| 145 | case DW_ATE_float: |
| 146 | switch (size) |
| 147 | { |
| 148 | case 4: /* float */ |
| 149 | case 8: /* double */ |
| 150 | *locp = loc_ssereg; |
| 151 | return nloc_ssereg; |
| 152 | case 16: /* long double */ |
| 153 | /* XXX distinguish __float128, which is sseregpair?? */ |
| 154 | *locp = loc_x87reg; |
| 155 | return nloc_x87reg; |
| 156 | } |
| 157 | return -2; |
| 158 | } |
| 159 | } |
| 160 | |
| 161 | intreg: |
| 162 | *locp = loc_intreg; |
| 163 | if (size <= 8) |
| 164 | return nloc_intreg; |
| 165 | if (size <= 16) |
| 166 | return nloc_intregpair; |
| 167 | |
| 168 | large: |
| 169 | *locp = loc_aggregate; |
| 170 | return nloc_aggregate; |
| 171 | |
| 172 | case DW_TAG_structure_type: |
| 173 | case DW_TAG_class_type: |
| 174 | case DW_TAG_union_type: |
| 175 | case DW_TAG_array_type: |
| 176 | if (dwarf_aggregate_size (typedie, &size) != 0) |
| 177 | goto large; |
| 178 | if (size > 16) |
| 179 | goto large; |
| 180 | |
| 181 | /* XXX |
| 182 | Must examine the fields in picayune ways to determine the |
| 183 | actual answer. This will be right for small C structs |
| 184 | containing integer types and similarly simple cases. |
| 185 | */ |
| 186 | |
| 187 | goto intreg; |
| 188 | } |
| 189 | |
| 190 | /* XXX We don't have a good way to return specific errors from ebl calls. |
| 191 | This value means we do not understand the type, but it is well-formed |
| 192 | DWARF and might be valid. */ |
| 193 | return -2; |
| 194 | } |