1 /* Function return value location for IA64 ABI. 2 Copyright (C) 2006-2010 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 ia64_ 34 #include "libebl_CPU.h" 35 36 37 /* r8, or pair r8, r9, or aggregate up to r8-r11. */ 38 static const Dwarf_Op loc_intreg[] = 39 { 40 { .atom = DW_OP_reg8 }, { .atom = DW_OP_piece, .number = 8 }, 41 { .atom = DW_OP_reg9 }, { .atom = DW_OP_piece, .number = 8 }, 42 { .atom = DW_OP_reg10 }, { .atom = DW_OP_piece, .number = 8 }, 43 { .atom = DW_OP_reg11 }, { .atom = DW_OP_piece, .number = 8 }, 44 }; 45 #define nloc_intreg 1 46 #define nloc_intregs(n) (2 * (n)) 47 48 /* f8, or aggregate up to f8-f15. */ 49 #define DEFINE_FPREG(size) \ 50 static const Dwarf_Op loc_fpreg_##size[] = \ 51 { \ 52 { .atom = DW_OP_regx, .number = 128 + 8 }, \ 53 { .atom = DW_OP_piece, .number = size }, \ 54 { .atom = DW_OP_regx, .number = 128 + 9 }, \ 55 { .atom = DW_OP_piece, .number = size }, \ 56 { .atom = DW_OP_regx, .number = 128 + 10 }, \ 57 { .atom = DW_OP_piece, .number = size }, \ 58 { .atom = DW_OP_regx, .number = 128 + 11 }, \ 59 { .atom = DW_OP_piece, .number = size }, \ 60 { .atom = DW_OP_regx, .number = 128 + 12 }, \ 61 { .atom = DW_OP_piece, .number = size }, \ 62 { .atom = DW_OP_regx, .number = 128 + 13 }, \ 63 { .atom = DW_OP_piece, .number = size }, \ 64 { .atom = DW_OP_regx, .number = 128 + 14 }, \ 65 { .atom = DW_OP_piece, .number = size }, \ 66 { .atom = DW_OP_regx, .number = 128 + 15 }, \ 67 { .atom = DW_OP_piece, .number = size }, \ 68 } 69 #define nloc_fpreg 1 70 #define nloc_fpregs(n) (2 * (n)) 71 72 DEFINE_FPREG (4); 73 DEFINE_FPREG (8); 74 DEFINE_FPREG (10); 75 76 #undef DEFINE_FPREG 77 78 79 /* The return value is a structure and is actually stored in stack space 80 passed in a hidden argument by the caller. But, the compiler 81 helpfully returns the address of that space in r8. */ 82 static const Dwarf_Op loc_aggregate[] = 83 { 84 { .atom = DW_OP_breg8, .number = 0 } 85 }; 86 #define nloc_aggregate 1 87 88 89 /* If this type is an HFA small enough to be returned in FP registers, 90 return the number of registers to use. Otherwise 9, or -1 for errors. */ 91 static int 92 hfa_type (Dwarf_Die *typedie, Dwarf_Word size, 93 const Dwarf_Op **locp, int fpregs_used) 94 { 95 /* Descend the type structure, counting elements and finding their types. 96 If we find a datum that's not an FP type (and not quad FP), punt. 97 If we find a datum that's not the same FP type as the first datum, punt. 98 If we count more than eight total homogeneous FP data, punt. */ 99 100 inline int hfa (const Dwarf_Op *loc, int nregs) 101 { 102 if (fpregs_used == 0) 103 *locp = loc; 104 else if (*locp != loc) 105 return 9; 106 return fpregs_used + nregs; 107 } 108 109 int tag = dwarf_tag (typedie); 110 switch (tag) 111 { 112 Dwarf_Attribute attr_mem; 113 114 case -1: 115 return -1; 116 117 case DW_TAG_base_type:; 118 Dwarf_Word encoding; 119 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding, 120 &attr_mem), &encoding) != 0) 121 return -1; 122 123 switch (encoding) 124 { 125 case DW_ATE_float: 126 switch (size) 127 { 128 case 4: /* float */ 129 return hfa (loc_fpreg_4, 1); 130 case 8: /* double */ 131 return hfa (loc_fpreg_8, 1); 132 case 10: /* x86-style long double, not really used */ 133 return hfa (loc_fpreg_10, 1); 134 } 135 break; 136 137 case DW_ATE_complex_float: 138 switch (size) 139 { 140 case 4 * 2: /* complex float */ 141 return hfa (loc_fpreg_4, 2); 142 case 8 * 2: /* complex double */ 143 return hfa (loc_fpreg_8, 2); 144 case 10 * 2: /* complex long double (x86-style) */ 145 return hfa (loc_fpreg_10, 2); 146 } 147 break; 148 } 149 break; 150 151 case DW_TAG_structure_type: 152 case DW_TAG_class_type: 153 case DW_TAG_union_type:; 154 Dwarf_Die child_mem; 155 switch (dwarf_child (typedie, &child_mem)) 156 { 157 default: 158 return -1; 159 160 case 1: /* No children: empty struct. */ 161 break; 162 163 case 0:; /* Look at each element. */ 164 int max_used = fpregs_used; 165 do 166 switch (dwarf_tag (&child_mem)) 167 { 168 case -1: 169 return -1; 170 171 case DW_TAG_member:; 172 Dwarf_Die child_type_mem; 173 Dwarf_Die *child_typedie 174 = dwarf_formref_die (dwarf_attr_integrate (&child_mem, 175 DW_AT_type, 176 &attr_mem), 177 &child_type_mem); 178 Dwarf_Word child_size; 179 if (dwarf_aggregate_size (child_typedie, &child_size) != 0) 180 return -1; 181 if (tag == DW_TAG_union_type) 182 { 183 int used = hfa_type (child_typedie, child_size, 184 locp, fpregs_used); 185 if (used < 0 || used > 8) 186 return used; 187 if (used > max_used) 188 max_used = used; 189 } 190 else 191 { 192 fpregs_used = hfa_type (child_typedie, child_size, 193 locp, fpregs_used); 194 if (fpregs_used < 0 || fpregs_used > 8) 195 return fpregs_used; 196 } 197 } 198 while (dwarf_siblingof (&child_mem, &child_mem) == 0); 199 if (tag == DW_TAG_union_type) 200 fpregs_used = max_used; 201 break; 202 } 203 break; 204 205 case DW_TAG_array_type: 206 if (size == 0) 207 break; 208 209 Dwarf_Die base_type_mem; 210 Dwarf_Die *base_typedie 211 = dwarf_formref_die (dwarf_attr_integrate (typedie, DW_AT_type, 212 &attr_mem), 213 &base_type_mem); 214 Dwarf_Word base_size; 215 if (dwarf_aggregate_size (base_typedie, &base_size) != 0) 216 return -1; 217 218 int used = hfa_type (base_typedie, base_size, locp, 0); 219 if (used < 0 || used > 8) 220 return used; 221 if (size % (*locp)[1].number != 0) 222 return 0; 223 fpregs_used += used * (size / (*locp)[1].number); 224 break; 225 226 default: 227 return 9; 228 } 229 230 return fpregs_used; 231 } 232 233 int 234 ia64_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp) 235 { 236 /* Start with the function's type, and get the DW_AT_type attribute, 237 which is the type of the return value. */ 238 239 Dwarf_Attribute attr_mem; 240 Dwarf_Attribute *attr = dwarf_attr_integrate (functypedie, DW_AT_type, 241 &attr_mem); 242 if (attr == NULL) 243 /* The function has no return value, like a `void' function in C. */ 244 return 0; 245 246 Dwarf_Die die_mem; 247 Dwarf_Die *typedie = dwarf_formref_die (attr, &die_mem); 248 int tag = dwarf_tag (typedie); 249 250 /* Follow typedefs and qualifiers to get to the actual type. */ 251 while (tag == DW_TAG_typedef 252 || tag == DW_TAG_const_type || tag == DW_TAG_volatile_type 253 || tag == DW_TAG_restrict_type || tag == DW_TAG_mutable_type) 254 { 255 attr = dwarf_attr (typedie, DW_AT_type, &attr_mem); 256 typedie = dwarf_formref_die (attr, &die_mem); 257 tag = dwarf_tag (typedie); 258 } 259 260 Dwarf_Word size; 261 switch (tag) 262 { 263 case -1: 264 return -1; 265 266 case DW_TAG_subrange_type: 267 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size)) 268 { 269 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); 270 typedie = dwarf_formref_die (attr, &die_mem); 271 tag = dwarf_tag (typedie); 272 } 273 /* Fall through. */ 274 275 case DW_TAG_base_type: 276 case DW_TAG_enumeration_type: 277 case DW_TAG_pointer_type: 278 case DW_TAG_ptr_to_member_type: 279 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size, 280 &attr_mem), &size) != 0) 281 { 282 if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) 283 size = 8; 284 else 285 return -1; 286 } 287 if (tag == DW_TAG_base_type) 288 { 289 Dwarf_Word encoding; 290 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding, 291 &attr_mem), 292 &encoding) != 0) 293 return -1; 294 295 switch (encoding) 296 { 297 case DW_ATE_float: 298 switch (size) 299 { 300 case 4: /* float */ 301 *locp = loc_fpreg_4; 302 return nloc_fpreg; 303 case 8: /* double */ 304 *locp = loc_fpreg_8; 305 return nloc_fpreg; 306 case 10: /* x86-style long double, not really used */ 307 *locp = loc_fpreg_10; 308 return nloc_fpreg; 309 case 16: /* long double, IEEE quad format */ 310 *locp = loc_intreg; 311 return nloc_intregs (2); 312 } 313 return -2; 314 315 case DW_ATE_complex_float: 316 switch (size) 317 { 318 case 4 * 2: /* complex float */ 319 *locp = loc_fpreg_4; 320 return nloc_fpregs (2); 321 case 8 * 2: /* complex double */ 322 *locp = loc_fpreg_8; 323 return nloc_fpregs (2); 324 case 10 * 2: /* complex long double (x86-style) */ 325 *locp = loc_fpreg_10; 326 return nloc_fpregs (2); 327 case 16 * 2: /* complex long double (IEEE quad) */ 328 *locp = loc_intreg; 329 return nloc_intregs (4); 330 } 331 return -2; 332 } 333 } 334 335 intreg: 336 *locp = loc_intreg; 337 if (size <= 8) 338 return nloc_intreg; 339 if (size <= 32) 340 return nloc_intregs ((size + 7) / 8); 341 342 large: 343 *locp = loc_aggregate; 344 return nloc_aggregate; 345 346 case DW_TAG_structure_type: 347 case DW_TAG_class_type: 348 case DW_TAG_union_type: 349 case DW_TAG_array_type: 350 if (dwarf_aggregate_size (typedie, &size) != 0) 351 return -1; 352 353 /* If this qualifies as an homogeneous floating-point aggregate 354 (HFA), then it should be returned in FP regs. */ 355 int nfpreg = hfa_type (typedie, size, locp, 0); 356 if (nfpreg < 0) 357 return nfpreg; 358 else if (nfpreg > 0 && nfpreg <= 8) 359 return nfpreg == 1 ? nloc_fpreg : nloc_fpregs (nfpreg); 360 361 if (size > 32) 362 goto large; 363 364 goto intreg; 365 } 366 367 /* XXX We don't have a good way to return specific errors from ebl calls. 368 This value means we do not understand the type, but it is well-formed 369 DWARF and might be valid. */ 370 return -2; 371 } 372
