| 1 | /* Target-dependent code for the TI TMS320C80 (MVP) 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, |
| 19 | Boston, MA 02111-1307, USA. */ |
| 20 | |
| 21 | #include "defs.h" |
| 22 | #include "value.h" |
| 23 | #include "frame.h" |
| 24 | #include "inferior.h" |
| 25 | #include "obstack.h" |
| 26 | #include "target.h" |
| 27 | #include "bfd.h" |
| 28 | #include "gdb_string.h" |
| 29 | #include "gdbcore.h" |
| 30 | #include "symfile.h" |
| 31 | |
| 32 | /* Function: frame_find_saved_regs |
| 33 | Return the frame_saved_regs structure for the frame. |
| 34 | Doesn't really work for dummy frames, but it does pass back |
| 35 | an empty frame_saved_regs, so I guess that's better than total failure */ |
| 36 | |
| 37 | void |
| 38 | tic80_frame_find_saved_regs (struct frame_info *fi, |
| 39 | struct frame_saved_regs *regaddr) |
| 40 | { |
| 41 | memcpy (regaddr, &fi->fsr, sizeof (struct frame_saved_regs)); |
| 42 | } |
| 43 | |
| 44 | /* Function: skip_prologue |
| 45 | Find end of function prologue. */ |
| 46 | |
| 47 | CORE_ADDR |
| 48 | tic80_skip_prologue (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: tic80_scan_prologue |
| 73 | This function decodes the target function prologue to determine: |
| 74 | 1) the size of the stack frame |
| 75 | 2) which registers are saved on it |
| 76 | 3) the offsets of saved regs |
| 77 | 4) the frame size |
| 78 | This information is stored in the "extra" fields of the frame_info. */ |
| 79 | |
| 80 | static void |
| 81 | tic80_scan_prologue (struct frame_info *fi) |
| 82 | { |
| 83 | struct symtab_and_line sal; |
| 84 | CORE_ADDR prologue_start, prologue_end, current_pc; |
| 85 | |
| 86 | /* Assume there is no frame until proven otherwise. */ |
| 87 | fi->framereg = SP_REGNUM; |
| 88 | fi->framesize = 0; |
| 89 | fi->frameoffset = 0; |
| 90 | |
| 91 | /* this code essentially duplicates skip_prologue, |
| 92 | but we need the start address below. */ |
| 93 | |
| 94 | if (find_pc_partial_function (fi->pc, NULL, &prologue_start, &prologue_end)) |
| 95 | { |
| 96 | sal = find_pc_line (prologue_start, 0); |
| 97 | |
| 98 | if (sal.line == 0) /* no line info, use current PC */ |
| 99 | if (prologue_start != entry_point_address ()) |
| 100 | prologue_end = fi->pc; |
| 101 | else |
| 102 | return; /* _start has no frame or prologue */ |
| 103 | else if (sal.end < prologue_end) /* next line begins after fn end */ |
| 104 | prologue_end = sal.end; /* (probably means no prologue) */ |
| 105 | } |
| 106 | else |
| 107 | /* FIXME */ |
| 108 | prologue_end = prologue_start + 40; /* We're in the boondocks: allow for */ |
| 109 | /* 16 pushes, an add, and "mv fp,sp" */ |
| 110 | |
| 111 | prologue_end = min (prologue_end, fi->pc); |
| 112 | |
| 113 | /* Now search the prologue looking for instructions that set up the |
| 114 | frame pointer, adjust the stack pointer, and save registers. */ |
| 115 | |
| 116 | for (current_pc = prologue_start; current_pc < prologue_end; current_pc += 4) |
| 117 | { |
| 118 | unsigned int insn; |
| 119 | int regno; |
| 120 | int offset = 0; |
| 121 | |
| 122 | insn = read_memory_unsigned_integer (current_pc, 4); |
| 123 | |
| 124 | if ((insn & 0x301000) == 0x301000) /* Long immediate? */ |
| 125 | /* FIXME - set offset for long immediate instructions */ |
| 126 | current_pc += 4; |
| 127 | else |
| 128 | { |
| 129 | offset = insn & 0x7fff; /* extract 15-bit offset */ |
| 130 | if (offset & 0x4000) /* if negative, sign-extend */ |
| 131 | offset = -(0x8000 - offset); |
| 132 | } |
| 133 | |
| 134 | if ((insn & 0x7fd0000) == 0x590000) /* st.{w,d} reg, xx(r1) */ |
| 135 | { |
| 136 | regno = ((insn >> 27) & 0x1f); |
| 137 | fi->fsr.regs[regno] = offset; |
| 138 | if (insn & 0x8000) /* 64-bit store (st.d)? */ |
| 139 | fi->fsr.regs[regno + 1] = offset + 4; |
| 140 | } |
| 141 | else if ((insn & 0xffff8000) == 0x086c8000) /* addu xx, r1, r1 */ |
| 142 | fi->framesize = -offset; |
| 143 | else if ((insn & 0xffff8000) == 0xf06c8000) /* addu xx, r1, r30 */ |
| 144 | { |
| 145 | fi->framereg = FP_REGNUM; /* fp is now valid */ |
| 146 | fi->frameoffset = offset; |
| 147 | break; /* end of stack adjustments */ |
| 148 | } |
| 149 | else if (insn == 0xf03b2001) /* addu r1, r0, r30 */ |
| 150 | { |
| 151 | fi->framereg = FP_REGNUM; /* fp is now valid */ |
| 152 | fi->frameoffset = 0; |
| 153 | break; /* end of stack adjustments */ |
| 154 | } |
| 155 | else |
| 156 | /* FIXME - handle long immediate instructions */ |
| 157 | break; /* anything else isn't prologue */ |
| 158 | } |
| 159 | } |
| 160 | |
| 161 | /* Function: init_extra_frame_info |
| 162 | This function actually figures out the frame address for a given pc and |
| 163 | sp. This is tricky on the c80 because we sometimes don't use an explicit |
| 164 | frame pointer, and the previous stack pointer isn't necessarily recorded |
| 165 | on the stack. The only reliable way to get this info is to |
| 166 | examine the prologue. */ |
| 167 | |
| 168 | void |
| 169 | tic80_init_extra_frame_info (struct frame_info *fi) |
| 170 | { |
| 171 | int reg; |
| 172 | |
| 173 | if (fi->next) |
| 174 | fi->pc = FRAME_SAVED_PC (fi->next); |
| 175 | |
| 176 | /* Because zero is a valid register offset relative to SP, we initialize |
| 177 | the offsets to -1 to indicate unused entries. */ |
| 178 | for (reg = 0; reg < NUM_REGS; reg++) |
| 179 | fi->fsr.regs[reg] = -1; |
| 180 | |
| 181 | if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame)) |
| 182 | { |
| 183 | /* We need to setup fi->frame here because run_stack_dummy gets it wrong |
| 184 | by assuming it's always FP. */ |
| 185 | fi->frame = generic_read_register_dummy (fi->pc, fi->frame, SP_REGNUM); |
| 186 | fi->framesize = 0; |
| 187 | fi->frameoffset = 0; |
| 188 | return; |
| 189 | } |
| 190 | else |
| 191 | { |
| 192 | tic80_scan_prologue (fi); |
| 193 | |
| 194 | if (!fi->next) /* this is the innermost frame? */ |
| 195 | fi->frame = read_register (fi->framereg); |
| 196 | else |
| 197 | /* not the innermost frame */ |
| 198 | /* If this function uses FP as the frame register, and the function |
| 199 | it called saved the FP, get the saved FP. */ if (fi->framereg == FP_REGNUM && |
| 200 | fi->next->fsr.regs[FP_REGNUM] != (unsigned) -1) |
| 201 | fi->frame = read_memory_integer (fi->next->fsr.regs[FP_REGNUM], 4); |
| 202 | |
| 203 | /* Convert SP-relative offsets of saved registers to real addresses. */ |
| 204 | for (reg = 0; reg < NUM_REGS; reg++) |
| 205 | if (fi->fsr.regs[reg] == (unsigned) -1) |
| 206 | fi->fsr.regs[reg] = 0; /* unused entry */ |
| 207 | else |
| 208 | fi->fsr.regs[reg] += fi->frame - fi->frameoffset; |
| 209 | } |
| 210 | } |
| 211 | |
| 212 | /* Function: find_callers_reg |
| 213 | Find REGNUM on the stack. Otherwise, it's in an active register. One thing |
| 214 | we might want to do here is to check REGNUM against the clobber mask, and |
| 215 | somehow flag it as invalid if it isn't saved on the stack somewhere. This |
| 216 | would provide a graceful failure mode when trying to get the value of |
| 217 | caller-saves registers for an inner frame. */ |
| 218 | |
| 219 | CORE_ADDR |
| 220 | tic80_find_callers_reg (struct frame_info *fi, int regnum) |
| 221 | { |
| 222 | for (; fi; fi = fi->next) |
| 223 | if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame)) |
| 224 | return generic_read_register_dummy (fi->pc, fi->frame, regnum); |
| 225 | else if (fi->fsr.regs[regnum] != 0) |
| 226 | return read_memory_integer (fi->fsr.regs[regnum], |
| 227 | REGISTER_RAW_SIZE (regnum)); |
| 228 | return read_register (regnum); |
| 229 | } |
| 230 | |
| 231 | /* Function: frame_chain |
| 232 | Given a GDB frame, determine the address of the calling function's frame. |
| 233 | This will be used to create a new GDB frame struct, and then |
| 234 | INIT_EXTRA_FRAME_INFO and INIT_FRAME_PC will be called for the new frame. |
| 235 | For c80, we save the frame size when we initialize the frame_info. */ |
| 236 | |
| 237 | CORE_ADDR |
| 238 | tic80_frame_chain (struct frame_info *fi) |
| 239 | { |
| 240 | CORE_ADDR fn_start, callers_pc, fp; |
| 241 | |
| 242 | /* is this a dummy frame? */ |
| 243 | if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame)) |
| 244 | return fi->frame; /* dummy frame same as caller's frame */ |
| 245 | |
| 246 | /* is caller-of-this a dummy frame? */ |
| 247 | callers_pc = FRAME_SAVED_PC (fi); /* find out who called us: */ |
| 248 | fp = tic80_find_callers_reg (fi, FP_REGNUM); |
| 249 | if (PC_IN_CALL_DUMMY (callers_pc, fp, fp)) |
| 250 | return fp; /* dummy frame's frame may bear no relation to ours */ |
| 251 | |
| 252 | if (find_pc_partial_function (fi->pc, 0, &fn_start, 0)) |
| 253 | if (fn_start == entry_point_address ()) |
| 254 | return 0; /* in _start fn, don't chain further */ |
| 255 | |
| 256 | if (fi->framereg == FP_REGNUM) |
| 257 | return tic80_find_callers_reg (fi, FP_REGNUM); |
| 258 | else |
| 259 | return fi->frame + fi->framesize; |
| 260 | } |
| 261 | |
| 262 | /* Function: pop_frame |
| 263 | Discard from the stack the innermost frame, |
| 264 | restoring all saved registers. */ |
| 265 | |
| 266 | struct frame_info * |
| 267 | tic80_pop_frame (struct frame_info *frame) |
| 268 | { |
| 269 | int regnum; |
| 270 | |
| 271 | if (PC_IN_CALL_DUMMY (frame->pc, frame->frame, frame->frame)) |
| 272 | generic_pop_dummy_frame (); |
| 273 | else |
| 274 | { |
| 275 | for (regnum = 0; regnum < NUM_REGS; regnum++) |
| 276 | if (frame->fsr.regs[regnum] != 0) |
| 277 | write_register (regnum, |
| 278 | read_memory_integer (frame->fsr.regs[regnum], 4)); |
| 279 | |
| 280 | write_register (PC_REGNUM, FRAME_SAVED_PC (frame)); |
| 281 | write_register (SP_REGNUM, read_register (FP_REGNUM)); |
| 282 | #if 0 |
| 283 | if (read_register (PSW_REGNUM) & 0x80) |
| 284 | write_register (SPU_REGNUM, read_register (SP_REGNUM)); |
| 285 | else |
| 286 | write_register (SPI_REGNUM, read_register (SP_REGNUM)); |
| 287 | #endif |
| 288 | } |
| 289 | flush_cached_frames (); |
| 290 | return NULL; |
| 291 | } |
| 292 | |
| 293 | /* Function: frame_saved_pc |
| 294 | Find the caller of this frame. We do this by seeing if LR_REGNUM is saved |
| 295 | in the stack anywhere, otherwise we get it from the registers. */ |
| 296 | |
| 297 | CORE_ADDR |
| 298 | tic80_frame_saved_pc (struct frame_info *fi) |
| 299 | { |
| 300 | if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame)) |
| 301 | return generic_read_register_dummy (fi->pc, fi->frame, PC_REGNUM); |
| 302 | else |
| 303 | return tic80_find_callers_reg (fi, LR_REGNUM); |
| 304 | } |
| 305 | |
| 306 | /* Function: tic80_push_return_address (pc, sp) |
| 307 | Set up the return address for the inferior function call. |
| 308 | Necessary for targets that don't actually execute a JSR/BSR instruction |
| 309 | (ie. when using an empty CALL_DUMMY) */ |
| 310 | |
| 311 | CORE_ADDR |
| 312 | tic80_push_return_address (CORE_ADDR pc, CORE_ADDR sp) |
| 313 | { |
| 314 | write_register (LR_REGNUM, CALL_DUMMY_ADDRESS ()); |
| 315 | return sp; |
| 316 | } |
| 317 | |
| 318 | |
| 319 | /* Function: push_arguments |
| 320 | Setup the function arguments for calling a function in the inferior. |
| 321 | |
| 322 | On the TI C80 architecture, there are six register pairs (R2/R3 to R12/13) |
| 323 | which are dedicated for passing function arguments. Up to the first six |
| 324 | arguments (depending on size) may go into these registers. |
| 325 | The rest go on the stack. |
| 326 | |
| 327 | Arguments that are smaller than 4 bytes will still take up a whole |
| 328 | register or a whole 32-bit word on the stack, and will be |
| 329 | right-justified in the register or the stack word. This includes |
| 330 | chars, shorts, and small aggregate types. |
| 331 | |
| 332 | Arguments that are four bytes or less in size are placed in the |
| 333 | even-numbered register of a register pair, and the odd-numbered |
| 334 | register is not used. |
| 335 | |
| 336 | Arguments of 8 bytes size (such as floating point doubles) are placed |
| 337 | in a register pair. The least significant 32-bit word is placed in |
| 338 | the even-numbered register, and the most significant word in the |
| 339 | odd-numbered register. |
| 340 | |
| 341 | Aggregate types with sizes between 4 and 8 bytes are passed |
| 342 | entirely on the stack, and are left-justified within the |
| 343 | double-word (as opposed to aggregates smaller than 4 bytes |
| 344 | which are right-justified). |
| 345 | |
| 346 | Aggregates of greater than 8 bytes are first copied onto the stack, |
| 347 | and then a pointer to the copy is passed in the place of the normal |
| 348 | argument (either in a register if available, or on the stack). |
| 349 | |
| 350 | Functions that must return an aggregate type can return it in the |
| 351 | normal return value registers (R2 and R3) if its size is 8 bytes or |
| 352 | less. For larger return values, the caller must allocate space for |
| 353 | the callee to copy the return value to. A pointer to this space is |
| 354 | passed as an implicit first argument, always in R0. */ |
| 355 | |
| 356 | CORE_ADDR |
| 357 | tic80_push_arguments (int nargs, value_ptr *args, CORE_ADDR sp, |
| 358 | unsigned char struct_return, CORE_ADDR struct_addr) |
| 359 | { |
| 360 | int stack_offset, stack_alloc; |
| 361 | int argreg; |
| 362 | int argnum; |
| 363 | struct type *type; |
| 364 | CORE_ADDR regval; |
| 365 | char *val; |
| 366 | char valbuf[4]; |
| 367 | int len; |
| 368 | int odd_sized_struct; |
| 369 | int is_struct; |
| 370 | |
| 371 | /* first force sp to a 4-byte alignment */ |
| 372 | sp = sp & ~3; |
| 373 | |
| 374 | argreg = ARG0_REGNUM; |
| 375 | /* The "struct return pointer" pseudo-argument goes in R0 */ |
| 376 | if (struct_return) |
| 377 | write_register (argreg++, struct_addr); |
| 378 | |
| 379 | /* Now make sure there's space on the stack */ |
| 380 | for (argnum = 0, stack_alloc = 0; |
| 381 | argnum < nargs; argnum++) |
| 382 | stack_alloc += ((TYPE_LENGTH (VALUE_TYPE (args[argnum])) + 3) & ~3); |
| 383 | sp -= stack_alloc; /* make room on stack for args */ |
| 384 | |
| 385 | |
| 386 | /* Now load as many as possible of the first arguments into |
| 387 | registers, and push the rest onto the stack. There are 16 bytes |
| 388 | in four registers available. Loop thru args from first to last. */ |
| 389 | |
| 390 | argreg = ARG0_REGNUM; |
| 391 | for (argnum = 0, stack_offset = 0; argnum < nargs; argnum++) |
| 392 | { |
| 393 | type = VALUE_TYPE (args[argnum]); |
| 394 | len = TYPE_LENGTH (type); |
| 395 | memset (valbuf, 0, sizeof (valbuf)); |
| 396 | val = (char *) VALUE_CONTENTS (args[argnum]); |
| 397 | |
| 398 | /* FIXME -- tic80 can take doubleword arguments in register pairs */ |
| 399 | is_struct = (type->code == TYPE_CODE_STRUCT); |
| 400 | odd_sized_struct = 0; |
| 401 | |
| 402 | if (!is_struct) |
| 403 | { |
| 404 | if (len < 4) |
| 405 | { /* value gets right-justified in the register or stack word */ |
| 406 | memcpy (valbuf + (4 - len), val, len); |
| 407 | val = valbuf; |
| 408 | } |
| 409 | if (len > 4 && (len & 3) != 0) |
| 410 | odd_sized_struct = 1; /* such structs go entirely on stack */ |
| 411 | } |
| 412 | else |
| 413 | { |
| 414 | /* Structs are always passed by reference. */ |
| 415 | write_register (argreg, sp + stack_offset); |
| 416 | argreg++; |
| 417 | } |
| 418 | |
| 419 | while (len > 0) |
| 420 | { |
| 421 | if (is_struct || argreg > ARGLAST_REGNUM || odd_sized_struct) |
| 422 | { /* must go on the stack */ |
| 423 | write_memory (sp + stack_offset, val, 4); |
| 424 | stack_offset += 4; |
| 425 | } |
| 426 | /* NOTE WELL!!!!! This is not an "else if" clause!!! |
| 427 | That's because some things get passed on the stack |
| 428 | AND in the registers! */ |
| 429 | if (!is_struct && argreg <= ARGLAST_REGNUM) |
| 430 | { /* there's room in a register */ |
| 431 | regval = extract_address (val, REGISTER_RAW_SIZE (argreg)); |
| 432 | write_register (argreg, regval); |
| 433 | argreg += 2; /* FIXME -- what about doubleword args? */ |
| 434 | } |
| 435 | /* Store the value 4 bytes at a time. This means that things |
| 436 | larger than 4 bytes may go partly in registers and partly |
| 437 | on the stack. */ |
| 438 | len -= REGISTER_RAW_SIZE (argreg); |
| 439 | val += REGISTER_RAW_SIZE (argreg); |
| 440 | } |
| 441 | } |
| 442 | return sp; |
| 443 | } |
| 444 | |
| 445 | /* Function: tic80_write_sp |
| 446 | Because SP is really a read-only register that mirrors either SPU or SPI, |
| 447 | we must actually write one of those two as well, depending on PSW. */ |
| 448 | |
| 449 | void |
| 450 | tic80_write_sp (CORE_ADDR val) |
| 451 | { |
| 452 | #if 0 |
| 453 | unsigned long psw = read_register (PSW_REGNUM); |
| 454 | |
| 455 | if (psw & 0x80) /* stack mode: user or interrupt */ |
| 456 | write_register (SPU_REGNUM, val); |
| 457 | else |
| 458 | write_register (SPI_REGNUM, val); |
| 459 | #endif |
| 460 | write_register (SP_REGNUM, val); |
| 461 | } |
| 462 | |
| 463 | void |
| 464 | _initialize_tic80_tdep (void) |
| 465 | { |
| 466 | tm_print_insn = print_insn_tic80; |
| 467 | } |