| 1 | /* Target-dependent code for the Mitsubishi m32r for GDB, the GNU debugger. |
| 2 | Copyright 1996, Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of GDB. |
| 5 | |
| 6 | This program is free software; you can redistribute it and/or modify |
| 7 | it under the terms of the GNU General Public License as published by |
| 8 | the Free Software Foundation; either version 2 of the License, or |
| 9 | (at your option) any later version. |
| 10 | |
| 11 | This program is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | GNU General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU General Public License |
| 17 | along with this program; if not, write to the Free Software |
| 18 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ |
| 19 | |
| 20 | #include "defs.h" |
| 21 | #include "frame.h" |
| 22 | #include "inferior.h" |
| 23 | #include "obstack.h" |
| 24 | #include "target.h" |
| 25 | #include "value.h" |
| 26 | #include "bfd.h" |
| 27 | #include "gdb_string.h" |
| 28 | #include "gdbcore.h" |
| 29 | #include "symfile.h" |
| 30 | |
| 31 | /* Function: frame_find_saved_regs |
| 32 | Return the frame_saved_regs structure for the frame. |
| 33 | Doesn't really work for dummy frames, but it does pass back |
| 34 | an empty frame_saved_regs, so I guess that's better than total failure */ |
| 35 | |
| 36 | void |
| 37 | m32r_frame_find_saved_regs PARAMS ((struct frame_info *fi, |
| 38 | struct frame_saved_regs *regaddr)) |
| 39 | { |
| 40 | memcpy(regaddr, &fi->fsr, sizeof(struct frame_saved_regs)); |
| 41 | } |
| 42 | |
| 43 | /* Function: skip_prologue |
| 44 | Find end of function prologue */ |
| 45 | |
| 46 | CORE_ADDR |
| 47 | m32r_skip_prologue (pc) |
| 48 | CORE_ADDR pc; |
| 49 | { |
| 50 | CORE_ADDR func_addr, func_end; |
| 51 | struct symtab_and_line sal; |
| 52 | |
| 53 | /* See what the symbol table says */ |
| 54 | |
| 55 | if (find_pc_partial_function (pc, NULL, &func_addr, &func_end)) |
| 56 | { |
| 57 | sal = find_pc_line (func_addr, 0); |
| 58 | |
| 59 | if (sal.line != 0 && sal.end < func_end) |
| 60 | return sal.end; |
| 61 | else |
| 62 | /* Either there's no line info, or the line after the prologue is after |
| 63 | the end of the function. In this case, there probably isn't a |
| 64 | prologue. */ |
| 65 | return pc; |
| 66 | } |
| 67 | |
| 68 | /* We can't find the start of this function, so there's nothing we can do. */ |
| 69 | return pc; |
| 70 | } |
| 71 | |
| 72 | /* Function: scan_prologue |
| 73 | This function decodes the target function prologue to determine |
| 74 | 1) the size of the stack frame, and 2) which registers are saved on it. |
| 75 | It saves the offsets of saved regs in the frame_saved_regs argument, |
| 76 | and returns the frame size. */ |
| 77 | |
| 78 | static unsigned long |
| 79 | m32r_scan_prologue (fi, fsr) |
| 80 | struct frame_info *fi; |
| 81 | struct frame_saved_regs *fsr; |
| 82 | { |
| 83 | struct symtab_and_line sal; |
| 84 | CORE_ADDR prologue_start, prologue_end, current_pc; |
| 85 | unsigned long framesize; |
| 86 | |
| 87 | /* this code essentially duplicates skip_prologue, |
| 88 | but we need the start address below. */ |
| 89 | |
| 90 | if (find_pc_partial_function (fi->pc, NULL, &prologue_start, &prologue_end)) |
| 91 | { |
| 92 | sal = find_pc_line (prologue_start, 0); |
| 93 | |
| 94 | if (sal.line == 0) /* no line info, use current PC */ |
| 95 | if (prologue_start != entry_point_address ()) |
| 96 | prologue_end = fi->pc; |
| 97 | else |
| 98 | return 0; /* _start has no frame or prologue */ |
| 99 | else if (sal.end < prologue_end) /* next line begins after fn end */ |
| 100 | prologue_end = sal.end; /* (probably means no prologue) */ |
| 101 | } |
| 102 | else |
| 103 | prologue_end = prologue_start + 40; /* We're in the boondocks: allow for */ |
| 104 | /* 16 pushes, an add, and "mv fp,sp" */ |
| 105 | |
| 106 | prologue_end = min (prologue_end, fi->pc); |
| 107 | |
| 108 | /* Now, search the prologue looking for instructions that setup fp, save |
| 109 | rp (and other regs), adjust sp and such. */ |
| 110 | |
| 111 | framesize = 0; |
| 112 | for (current_pc = prologue_start; current_pc < prologue_end; current_pc += 2) |
| 113 | { |
| 114 | int insn; |
| 115 | int regno; |
| 116 | |
| 117 | insn = read_memory_unsigned_integer (current_pc, 2); |
| 118 | if (insn & 0x8000) /* Four byte instruction? */ |
| 119 | current_pc += 2; |
| 120 | |
| 121 | if ((insn & 0xf0ff) == 0x207f) { /* st reg, @-sp */ |
| 122 | framesize += 4; |
| 123 | regno = ((insn >> 8) & 0xf); |
| 124 | if (fsr) /* save_regs offset */ |
| 125 | fsr->regs[regno] = framesize; |
| 126 | } |
| 127 | else if ((insn >> 8) == 0x4f) /* addi sp, xx */ |
| 128 | /* add 8 bit sign-extended offset */ |
| 129 | framesize += -((char) (insn & 0xff)); |
| 130 | else if (insn == 0x8faf) /* add3 sp, sp, xxxx */ |
| 131 | /* add 16 bit sign-extended offset */ |
| 132 | framesize += -((short) read_memory_unsigned_integer (current_pc, 2)); |
| 133 | else if (((insn >> 8) == 0xe4) && /* ld24 r4, xxxxxx ; sub sp, r4 */ |
| 134 | read_memory_unsigned_integer (current_pc + 2, 2) == 0x0f24) |
| 135 | { /* subtract 24 bit sign-extended negative-offset */ |
| 136 | insn = read_memory_unsigned_integer (current_pc - 2, 4); |
| 137 | if (insn & 0x00800000) /* sign extend */ |
| 138 | insn |= 0xff000000; /* negative */ |
| 139 | else |
| 140 | insn &= 0x00ffffff; /* positive */ |
| 141 | framesize += insn; |
| 142 | } |
| 143 | else if (insn == 0x1d8f) { /* mv fp, sp */ |
| 144 | fi->using_frame_pointer = 1; /* fp is now valid */ |
| 145 | break; /* end of stack adjustments */ |
| 146 | } |
| 147 | else |
| 148 | break; /* anything else isn't prologue */ |
| 149 | } |
| 150 | return framesize; |
| 151 | } |
| 152 | |
| 153 | /* Function: init_extra_frame_info |
| 154 | This function actually figures out the frame address for a given pc and |
| 155 | sp. This is tricky on the m32r because we sometimes don't use an explicit |
| 156 | frame pointer, and the previous stack pointer isn't necessarily recorded |
| 157 | on the stack. The only reliable way to get this info is to |
| 158 | examine the prologue. */ |
| 159 | |
| 160 | void |
| 161 | m32r_init_extra_frame_info (fi) |
| 162 | struct frame_info *fi; |
| 163 | { |
| 164 | int reg; |
| 165 | |
| 166 | if (fi->next) |
| 167 | fi->pc = FRAME_SAVED_PC (fi->next); |
| 168 | |
| 169 | memset (fi->fsr.regs, '\000', sizeof fi->fsr.regs); |
| 170 | |
| 171 | if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame)) |
| 172 | { |
| 173 | /* We need to setup fi->frame here because run_stack_dummy gets it wrong |
| 174 | by assuming it's always FP. */ |
| 175 | fi->frame = generic_read_register_dummy (fi->pc, fi->frame, SP_REGNUM); |
| 176 | fi->framesize = 0; |
| 177 | return; |
| 178 | } |
| 179 | else |
| 180 | { |
| 181 | fi->using_frame_pointer = 0; |
| 182 | fi->framesize = m32r_scan_prologue (fi, &fi->fsr); |
| 183 | |
| 184 | if (!fi->next) |
| 185 | if (fi->using_frame_pointer) |
| 186 | fi->frame = read_register (FP_REGNUM); |
| 187 | else |
| 188 | fi->frame = read_register (SP_REGNUM); |
| 189 | else /* fi->next means this is not the innermost frame */ |
| 190 | if (fi->using_frame_pointer) /* we have an FP */ |
| 191 | if (fi->next->fsr.regs[FP_REGNUM] != 0) /* caller saved our FP */ |
| 192 | fi->frame = read_memory_integer (fi->next->fsr.regs[FP_REGNUM], 4); |
| 193 | for (reg = 0; reg < NUM_REGS; reg++) |
| 194 | if (fi->fsr.regs[reg] != 0) |
| 195 | fi->fsr.regs[reg] = fi->frame + fi->framesize - fi->fsr.regs[reg]; |
| 196 | } |
| 197 | } |
| 198 | |
| 199 | /* Function: find_callers_reg |
| 200 | Find REGNUM on the stack. Otherwise, it's in an active register. One thing |
| 201 | we might want to do here is to check REGNUM against the clobber mask, and |
| 202 | somehow flag it as invalid if it isn't saved on the stack somewhere. This |
| 203 | would provide a graceful failure mode when trying to get the value of |
| 204 | caller-saves registers for an inner frame. */ |
| 205 | |
| 206 | CORE_ADDR |
| 207 | m32r_find_callers_reg (fi, regnum) |
| 208 | struct frame_info *fi; |
| 209 | int regnum; |
| 210 | { |
| 211 | for (; fi; fi = fi->next) |
| 212 | if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame)) |
| 213 | return generic_read_register_dummy (fi->pc, fi->frame, regnum); |
| 214 | else if (fi->fsr.regs[regnum] != 0) |
| 215 | return read_memory_integer (fi->fsr.regs[regnum], |
| 216 | REGISTER_RAW_SIZE(regnum)); |
| 217 | return read_register (regnum); |
| 218 | } |
| 219 | |
| 220 | /* Function: frame_chain |
| 221 | Given a GDB frame, determine the address of the calling function's frame. |
| 222 | This will be used to create a new GDB frame struct, and then |
| 223 | INIT_EXTRA_FRAME_INFO and INIT_FRAME_PC will be called for the new frame. |
| 224 | For m32r, we save the frame size when we initialize the frame_info. */ |
| 225 | |
| 226 | CORE_ADDR |
| 227 | m32r_frame_chain (fi) |
| 228 | struct frame_info *fi; |
| 229 | { |
| 230 | CORE_ADDR fn_start, callers_pc, fp; |
| 231 | |
| 232 | /* is this a dummy frame? */ |
| 233 | if (PC_IN_CALL_DUMMY(fi->pc, fi->frame, fi->frame)) |
| 234 | return fi->frame; /* dummy frame same as caller's frame */ |
| 235 | |
| 236 | /* is caller-of-this a dummy frame? */ |
| 237 | callers_pc = FRAME_SAVED_PC(fi); /* find out who called us: */ |
| 238 | fp = m32r_find_callers_reg (fi, FP_REGNUM); |
| 239 | if (PC_IN_CALL_DUMMY(callers_pc, fp, fp)) |
| 240 | return fp; /* dummy frame's frame may bear no relation to ours */ |
| 241 | |
| 242 | if (find_pc_partial_function (fi->pc, 0, &fn_start, 0)) |
| 243 | if (fn_start == entry_point_address ()) |
| 244 | return 0; /* in _start fn, don't chain further */ |
| 245 | return fi->frame + fi->framesize; |
| 246 | } |
| 247 | |
| 248 | /* Function: push_return_address (pc) |
| 249 | Set up the return address for the inferior function call. |
| 250 | Necessary for targets that don't actually execute a JSR/BSR instruction |
| 251 | (ie. when using an empty CALL_DUMMY) */ |
| 252 | |
| 253 | CORE_ADDR |
| 254 | m32r_push_return_address (pc, sp) |
| 255 | CORE_ADDR pc; |
| 256 | CORE_ADDR sp; |
| 257 | { |
| 258 | #if CALL_DUMMY_LOCATION != AT_ENTRY_POINT |
| 259 | pc = pc - CALL_DUMMY_START_OFFSET + CALL_DUMMY_BREAKPOINT_OFFSET; |
| 260 | #else |
| 261 | pc = CALL_DUMMY_ADDRESS (); |
| 262 | #endif |
| 263 | write_register (RP_REGNUM, pc); |
| 264 | return sp; |
| 265 | } |
| 266 | |
| 267 | |
| 268 | /* Function: pop_frame |
| 269 | Discard from the stack the innermost frame, |
| 270 | restoring all saved registers. */ |
| 271 | |
| 272 | struct frame_info * |
| 273 | m32r_pop_frame (frame) |
| 274 | struct frame_info *frame; |
| 275 | { |
| 276 | int regnum; |
| 277 | |
| 278 | if (PC_IN_CALL_DUMMY (frame->pc, frame->frame, frame->frame)) |
| 279 | generic_pop_dummy_frame (); |
| 280 | else |
| 281 | { |
| 282 | for (regnum = 0; regnum < NUM_REGS; regnum++) |
| 283 | if (frame->fsr.regs[regnum] != 0) |
| 284 | write_register (regnum, |
| 285 | read_memory_integer (frame->fsr.regs[regnum], 4)); |
| 286 | |
| 287 | write_register (PC_REGNUM, FRAME_SAVED_PC (frame)); |
| 288 | write_register (SP_REGNUM, read_register (FP_REGNUM)); |
| 289 | if (read_register (PSW_REGNUM) & 0x80) |
| 290 | write_register (SPU_REGNUM, read_register (SP_REGNUM)); |
| 291 | else |
| 292 | write_register (SPI_REGNUM, read_register (SP_REGNUM)); |
| 293 | } |
| 294 | flush_cached_frames (); |
| 295 | return NULL; |
| 296 | } |
| 297 | |
| 298 | /* Function: frame_saved_pc |
| 299 | Find the caller of this frame. We do this by seeing if RP_REGNUM is saved |
| 300 | in the stack anywhere, otherwise we get it from the registers. */ |
| 301 | |
| 302 | CORE_ADDR |
| 303 | m32r_frame_saved_pc (fi) |
| 304 | struct frame_info *fi; |
| 305 | { |
| 306 | if (PC_IN_CALL_DUMMY(fi->pc, fi->frame, fi->frame)) |
| 307 | return generic_read_register_dummy(fi->pc, fi->frame, PC_REGNUM); |
| 308 | else |
| 309 | return m32r_find_callers_reg (fi, RP_REGNUM); |
| 310 | } |
| 311 | |
| 312 | /* Function: push_arguments |
| 313 | Setup the function arguments for calling a function in the inferior. |
| 314 | |
| 315 | On the Mitsubishi M32R architecture, there are four registers (R0 to R3) |
| 316 | which are dedicated for passing function arguments. Up to the first |
| 317 | four arguments (depending on size) may go into these registers. |
| 318 | The rest go on the stack. |
| 319 | |
| 320 | Arguments that are smaller than 4 bytes will still take up a whole |
| 321 | register or a whole 32-bit word on the stack, and will be |
| 322 | right-justified in the register or the stack word. This includes |
| 323 | chars, shorts, and small aggregate types. |
| 324 | |
| 325 | Arguments of 8 bytes size are split between two registers, if |
| 326 | available. If only one register is available, the argument will |
| 327 | be split between the register and the stack. Otherwise it is |
| 328 | passed entirely on the stack. Aggregate types with sizes between |
| 329 | 4 and 8 bytes are passed entirely on the stack, and are left-justified |
| 330 | within the double-word (as opposed to aggregates smaller than 4 bytes |
| 331 | which are right-justified). |
| 332 | |
| 333 | Aggregates of greater than 8 bytes are first copied onto the stack, |
| 334 | and then a pointer to the copy is passed in the place of the normal |
| 335 | argument (either in a register if available, or on the stack). |
| 336 | |
| 337 | Functions that must return an aggregate type can return it in the |
| 338 | normal return value registers (R0 and R1) if its size is 8 bytes or |
| 339 | less. For larger return values, the caller must allocate space for |
| 340 | the callee to copy the return value to. A pointer to this space is |
| 341 | passed as an implicit first argument, always in R0. */ |
| 342 | |
| 343 | CORE_ADDR |
| 344 | m32r_push_arguments (nargs, args, sp, struct_return, struct_addr) |
| 345 | int nargs; |
| 346 | value_ptr *args; |
| 347 | CORE_ADDR sp; |
| 348 | unsigned char struct_return; |
| 349 | CORE_ADDR struct_addr; |
| 350 | { |
| 351 | int stack_offset, stack_alloc; |
| 352 | int argreg; |
| 353 | int argnum; |
| 354 | struct type *type; |
| 355 | CORE_ADDR regval; |
| 356 | char *val; |
| 357 | char valbuf[4]; |
| 358 | int len; |
| 359 | int odd_sized_struct; |
| 360 | |
| 361 | /* first force sp to a 4-byte alignment */ |
| 362 | sp = sp & ~3; |
| 363 | |
| 364 | argreg = ARG0_REGNUM; |
| 365 | /* The "struct return pointer" pseudo-argument goes in R0 */ |
| 366 | if (struct_return) |
| 367 | write_register (argreg++, struct_addr); |
| 368 | |
| 369 | /* Now make sure there's space on the stack */ |
| 370 | for (argnum = 0, stack_alloc = 0; |
| 371 | argnum < nargs; argnum++) |
| 372 | stack_alloc += ((TYPE_LENGTH(VALUE_TYPE(args[argnum])) + 3) & ~3); |
| 373 | sp -= stack_alloc; /* make room on stack for args */ |
| 374 | |
| 375 | |
| 376 | /* Now load as many as possible of the first arguments into |
| 377 | registers, and push the rest onto the stack. There are 16 bytes |
| 378 | in four registers available. Loop thru args from first to last. */ |
| 379 | |
| 380 | argreg = ARG0_REGNUM; |
| 381 | for (argnum = 0, stack_offset = 0; argnum < nargs; argnum++) |
| 382 | { |
| 383 | type = VALUE_TYPE (args[argnum]); |
| 384 | len = TYPE_LENGTH (type); |
| 385 | memset(valbuf, 0, sizeof(valbuf)); |
| 386 | if (len < 4) |
| 387 | { /* value gets right-justified in the register or stack word */ |
| 388 | memcpy(valbuf + (4 - len), |
| 389 | (char *) VALUE_CONTENTS (args[argnum]), len); |
| 390 | val = valbuf; |
| 391 | } |
| 392 | else |
| 393 | val = (char *) VALUE_CONTENTS (args[argnum]); |
| 394 | |
| 395 | if (len > 4 && (len & 3) != 0) |
| 396 | odd_sized_struct = 1; /* such structs go entirely on stack */ |
| 397 | else |
| 398 | odd_sized_struct = 0; |
| 399 | while (len > 0) |
| 400 | { |
| 401 | if (argreg > ARGLAST_REGNUM || odd_sized_struct) |
| 402 | { /* must go on the stack */ |
| 403 | write_memory (sp + stack_offset, val, 4); |
| 404 | stack_offset += 4; |
| 405 | } |
| 406 | /* NOTE WELL!!!!! This is not an "else if" clause!!! |
| 407 | That's because some *&^%$ things get passed on the stack |
| 408 | AND in the registers! */ |
| 409 | if (argreg <= ARGLAST_REGNUM) |
| 410 | { /* there's room in a register */ |
| 411 | regval = extract_address (val, REGISTER_RAW_SIZE(argreg)); |
| 412 | write_register (argreg++, regval); |
| 413 | } |
| 414 | /* Store the value 4 bytes at a time. This means that things |
| 415 | larger than 4 bytes may go partly in registers and partly |
| 416 | on the stack. */ |
| 417 | len -= REGISTER_RAW_SIZE(argreg); |
| 418 | val += REGISTER_RAW_SIZE(argreg); |
| 419 | } |
| 420 | } |
| 421 | return sp; |
| 422 | } |
| 423 | |
| 424 | /* Function: fix_call_dummy |
| 425 | If there is real CALL_DUMMY code (eg. on the stack), this function |
| 426 | has the responsability to insert the address of the actual code that |
| 427 | is the target of the target function call. */ |
| 428 | |
| 429 | int |
| 430 | m32r_fix_call_dummy (dummy, pc, fun, nargs, args, type, gcc_p) |
| 431 | char *dummy; |
| 432 | CORE_ADDR pc; |
| 433 | CORE_ADDR fun; |
| 434 | int nargs; |
| 435 | value_ptr *args; |
| 436 | struct type *type; |
| 437 | int gcc_p; |
| 438 | { |
| 439 | /* ld24 r8, <(imm24) fun> */ |
| 440 | *(unsigned long *) (dummy) = (fun & 0x00ffffff) | 0xe8000000; |
| 441 | } |
| 442 | |
| 443 | /* Function: get_saved_register |
| 444 | Just call the generic_get_saved_register function. */ |
| 445 | |
| 446 | void |
| 447 | get_saved_register (raw_buffer, optimized, addrp, frame, regnum, lval) |
| 448 | char *raw_buffer; |
| 449 | int *optimized; |
| 450 | CORE_ADDR *addrp; |
| 451 | struct frame_info *frame; |
| 452 | int regnum; |
| 453 | enum lval_type *lval; |
| 454 | { |
| 455 | generic_get_saved_register (raw_buffer, optimized, addrp, |
| 456 | frame, regnum, lval); |
| 457 | } |
| 458 | |
| 459 | |
| 460 | /* Function: m32r_write_sp |
| 461 | Because SP is really a read-only register that mirrors either SPU or SPI, |
| 462 | we must actually write one of those two as well, depending on PSW. */ |
| 463 | |
| 464 | void |
| 465 | m32r_write_sp (val) |
| 466 | CORE_ADDR val; |
| 467 | { |
| 468 | unsigned long psw = read_register (PSW_REGNUM); |
| 469 | |
| 470 | if (psw & 0x80) /* stack mode: user or interrupt */ |
| 471 | write_register (SPU_REGNUM, val); |
| 472 | else |
| 473 | write_register (SPI_REGNUM, val); |
| 474 | write_register (SP_REGNUM, val); |
| 475 | } |
| 476 | |
| 477 | void |
| 478 | _initialize_m32r_tdep () |
| 479 | { |
| 480 | tm_print_insn = print_insn_m32r; |
| 481 | } |
| 482 | |