1 /* Function return value location for Linux/x86-64 ABI. 2 Copyright (C) 2005, 2007 Red Hat, Inc. 3 This file is part of Red Hat elfutils. 4 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. 8 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. 13 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. 17 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>. */ 25 26 #ifdef HAVE_CONFIG_H 27 # include <config.h> 28 #endif 29 30 #include <assert.h> 31 #include <dwarf.h> 32 33 #define BACKEND x86_64_ 34 #include "libebl_CPU.h" 35 36 37 /* %rax, or pair %rax, %rdx. */ 38 static const Dwarf_Op loc_intreg[] = 39 { 40 { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 8 }, 41 { .atom = DW_OP_reg1 }, { .atom = DW_OP_piece, .number = 8 }, 42 }; 43 #define nloc_intreg 1 44 #define nloc_intregpair 4 45 46 /* %st(0), or pair %st(0), %st(1). */ 47 static const Dwarf_Op loc_x87reg[] = 48 { 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 }, 53 }; 54 #define nloc_x87reg 1 55 #define nloc_x87regpair 4 56 57 /* %xmm0, or pair %xmm0, %xmm1. */ 58 static const Dwarf_Op loc_ssereg[] = 59 { 60 { .atom = DW_OP_reg17 }, { .atom = DW_OP_piece, .number = 16 }, 61 { .atom = DW_OP_reg18 }, { .atom = DW_OP_piece, .number = 16 }, 62 }; 63 #define nloc_ssereg 1 64 #define nloc_sseregpair 4 65 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[] = 70 { 71 { .atom = DW_OP_breg0, .number = 0 } 72 }; 73 #define nloc_aggregate 1 74 75 76 int 77 x86_64_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp) 78 { 79 /* Start with the function's type, and get the DW_AT_type attribute, 80 which is the type of the return value. */ 81 82 Dwarf_Attribute attr_mem; 83 Dwarf_Attribute *attr = dwarf_attr_integrate (functypedie, DW_AT_type, 84 &attr_mem); 85 if (attr == NULL) 86 /* The function has no return value, like a `void' function in C. */ 87 return 0; 88 89 Dwarf_Die die_mem; 90 Dwarf_Die *typedie = dwarf_formref_die (attr, &die_mem); 91 int tag = dwarf_tag (typedie); 92 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) 97 { 98 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); 99 typedie = dwarf_formref_die (attr, &die_mem); 100 tag = dwarf_tag (typedie); 101 } 102 103 Dwarf_Word size; 104 switch (tag) 105 { 106 case -1: 107 return -1; 108 109 case DW_TAG_subrange_type: 110 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size)) 111 { 112 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); 113 typedie = dwarf_formref_die (attr, &die_mem); 114 tag = dwarf_tag (typedie); 115 } 116 /* Fall through. */ 117 118 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) 124 { 125 if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) 126 size = 8; 127 else 128 return -1; 129 } 130 if (tag == DW_TAG_base_type) 131 { 132 Dwarf_Word encoding; 133 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding, 134 &attr_mem), 135 &encoding) != 0) 136 return -1; 137 138 switch (encoding) 139 { 140 case DW_ATE_complex_float: 141 switch (size) 142 { 143 case 4 * 2: /* complex float */ 144 case 8 * 2: /* complex double */ 145 *locp = loc_ssereg; 146 return nloc_sseregpair; 147 case 16 * 2: /* complex long double */ 148 *locp = loc_x87reg; 149 return nloc_x87regpair; 150 } 151 return -2; 152 153 case DW_ATE_float: 154 switch (size) 155 { 156 case 4: /* float */ 157 case 8: /* double */ 158 *locp = loc_ssereg; 159 return nloc_ssereg; 160 case 16: /* long double */ 161 /* XXX distinguish __float128, which is sseregpair?? */ 162 *locp = loc_x87reg; 163 return nloc_x87reg; 164 } 165 return -2; 166 } 167 } 168 169 intreg: 170 *locp = loc_intreg; 171 if (size <= 8) 172 return nloc_intreg; 173 if (size <= 16) 174 return nloc_intregpair; 175 176 large: 177 *locp = loc_aggregate; 178 return nloc_aggregate; 179 180 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_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size, 185 &attr_mem), &size) != 0) 186 return -1; 187 if (size > 16) 188 goto large; 189 190 /* XXX 191 Must examine the fields in picayune ways to determine the 192 actual answer. This will be right for small C structs 193 containing integer types and similarly simple cases. 194 */ 195 196 goto intreg; 197 } 198 199 /* XXX We don't have a good way to return specific errors from ebl calls. 200 This value means we do not understand the type, but it is well-formed 201 DWARF and might be valid. */ 202 return -2; 203 } 204
