1 /* dw2gencfi.c - Support for generating Dwarf2 CFI information.
2 Copyright 2003 Free Software Foundation, Inc.
3 Contributed by Michal Ludvig <mludvig@suse.cz>
5 This file is part of GAS, the GNU Assembler.
7 GAS is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GAS is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GAS; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 #include "dw2gencfi.h"
26 /* We re-use DWARF2_LINE_MIN_INSN_LENGTH for the code alignment field
27 of the CIE. Default to 1 if not otherwise specified. */
28 #ifndef DWARF2_LINE_MIN_INSN_LENGTH
29 # define DWARF2_LINE_MIN_INSN_LENGTH 1
32 /* If TARGET_USE_CFIPOP is defined, it is required that the target
33 provide the following definitions. Otherwise provide them to
34 allow compilation to continue. */
35 #ifndef TARGET_USE_CFIPOP
36 # ifndef DWARF2_DEFAULT_RETURN_COLUMN
37 # define DWARF2_DEFAULT_RETURN_COLUMN 0
39 # ifndef DWARF2_CIE_DATA_ALIGNMENT
40 # define DWARF2_CIE_DATA_ALIGNMENT 1
44 #ifndef tc_cfi_frame_initial_instructions
45 # define tc_cfi_frame_initial_instructions() ((void)0)
51 struct cfi_insn_data *next;
76 struct fde_entry *next;
77 symbolS *start_address;
79 struct cfi_insn_data *data;
80 struct cfi_insn_data **last;
81 unsigned int return_column;
86 struct cie_entry *next;
87 symbolS *start_address;
88 unsigned int return_column;
89 struct cfi_insn_data *first, *last;
93 /* Current open FDE entry. */
94 static struct fde_entry *cur_fde_data;
95 static symbolS *last_address;
96 static offsetT cur_cfa_offset;
98 /* List of FDE entries. */
99 static struct fde_entry *all_fde_data;
100 static struct fde_entry **last_fde_data = &all_fde_data;
102 /* List of CIEs so that they could be reused. */
103 static struct cie_entry *cie_root;
106 /* Construct a new FDE structure and add it to the end of the fde list. */
108 static struct fde_entry *
109 alloc_fde_entry (void)
111 struct fde_entry *fde = xcalloc (1, sizeof (struct fde_entry));
114 *last_fde_data = fde;
115 last_fde_data = &fde->next;
117 fde->last = &fde->data;
118 fde->return_column = DWARF2_DEFAULT_RETURN_COLUMN;
123 /* The following functions are available for a backend to construct its
124 own unwind information, usually from legacy unwind directives. */
126 /* Construct a new INSN structure and add it to the end of the insn list
127 for the currently active FDE. */
129 static struct cfi_insn_data *
130 alloc_cfi_insn_data (void)
132 struct cfi_insn_data *insn = xcalloc (1, sizeof (struct cfi_insn_data));
134 *cur_fde_data->last = insn;
135 cur_fde_data->last = &insn->next;
140 /* Construct a new FDE structure that begins at LABEL. */
143 cfi_new_fde (symbolS *label)
145 struct fde_entry *fde = alloc_fde_entry ();
146 fde->start_address = label;
147 last_address = label;
150 /* End the currently open FDE. */
153 cfi_end_fde (symbolS *label)
155 cur_fde_data->end_address = label;
159 /* Set the return column for the current FDE. */
162 cfi_set_return_column (unsigned regno)
164 cur_fde_data->return_column = regno;
167 /* Universal functions to store new instructions. */
170 cfi_add_CFA_insn(int insn)
172 struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
174 insn_ptr->insn = insn;
178 cfi_add_CFA_insn_reg (int insn, unsigned regno)
180 struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
182 insn_ptr->insn = insn;
183 insn_ptr->u.r = regno;
187 cfi_add_CFA_insn_offset (int insn, offsetT offset)
189 struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
191 insn_ptr->insn = insn;
192 insn_ptr->u.i = offset;
196 cfi_add_CFA_insn_reg_reg (int insn, unsigned reg1, unsigned reg2)
198 struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
200 insn_ptr->insn = insn;
201 insn_ptr->u.rr.reg1 = reg1;
202 insn_ptr->u.rr.reg2 = reg2;
206 cfi_add_CFA_insn_reg_offset (int insn, unsigned regno, offsetT offset)
208 struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
210 insn_ptr->insn = insn;
211 insn_ptr->u.ri.reg = regno;
212 insn_ptr->u.ri.offset = offset;
215 /* Add a CFI insn to advance the PC from the last address to LABEL. */
218 cfi_add_advance_loc (symbolS *label)
220 struct cfi_insn_data *insn = alloc_cfi_insn_data ();
222 insn->insn = DW_CFA_advance_loc;
223 insn->u.ll.lab1 = last_address;
224 insn->u.ll.lab2 = label;
226 last_address = label;
229 /* Add a DW_CFA_offset record to the CFI data. */
232 cfi_add_CFA_offset (unsigned regno, offsetT offset)
234 cfi_add_CFA_insn_reg_offset (DW_CFA_offset, regno, offset);
237 /* Add a DW_CFA_def_cfa record to the CFI data. */
240 cfi_add_CFA_def_cfa (unsigned regno, offsetT offset)
242 cfi_add_CFA_insn_reg_offset (DW_CFA_def_cfa, regno, offset);
243 cur_cfa_offset = offset;
246 /* Add a DW_CFA_register record to the CFI data. */
249 cfi_add_CFA_register (unsigned reg1, unsigned reg2)
251 cfi_add_CFA_insn_reg_reg (DW_CFA_register, reg1, reg2);
254 /* Add a DW_CFA_def_cfa_register record to the CFI data. */
257 cfi_add_CFA_def_cfa_register (unsigned regno)
259 cfi_add_CFA_insn_reg (DW_CFA_def_cfa_register, regno);
262 /* Add a DW_CFA_def_cfa_offset record to the CFI data. */
265 cfi_add_CFA_def_cfa_offset (offsetT offset)
267 cfi_add_CFA_insn_offset (DW_CFA_def_cfa_offset, offset);
268 cur_cfa_offset = offset;
272 cfi_add_CFA_restore (unsigned regno)
274 cfi_add_CFA_insn_reg (DW_CFA_restore, regno);
278 cfi_add_CFA_undefined (unsigned regno)
280 cfi_add_CFA_insn_reg (DW_CFA_undefined, regno);
284 cfi_add_CFA_same_value (unsigned regno)
286 cfi_add_CFA_insn_reg (DW_CFA_same_value, regno);
290 cfi_add_CFA_remember_state (void)
292 cfi_add_CFA_insn (DW_CFA_remember_state);
296 cfi_add_CFA_restore_state (void)
298 cfi_add_CFA_insn (DW_CFA_restore_state);
302 cfi_add_CFA_nop (void)
304 cfi_add_CFA_insn (DW_CFA_nop);
308 /* Parse CFI assembler directives. */
310 static void dot_cfi (int);
311 static void dot_cfi_startproc (int);
312 static void dot_cfi_endproc (int);
314 /* Fake CFI type; outside the byte range of any real CFI insn. */
315 #define CFI_adjust_cfa_offset 0x100
316 #define CFI_return_column 0x101
318 const pseudo_typeS cfi_pseudo_table[] =
320 { "cfi_startproc", dot_cfi_startproc, 0 },
321 { "cfi_endproc", dot_cfi_endproc, 0 },
322 { "cfi_def_cfa", dot_cfi, DW_CFA_def_cfa },
323 { "cfi_def_cfa_register", dot_cfi, DW_CFA_def_cfa_register },
324 { "cfi_def_cfa_offset", dot_cfi, DW_CFA_def_cfa_offset },
325 { "cfi_adjust_cfa_offset", dot_cfi, CFI_adjust_cfa_offset },
326 { "cfi_offset", dot_cfi, DW_CFA_offset },
327 { "cfi_register", dot_cfi, DW_CFA_register },
328 { "cfi_return_column", dot_cfi, CFI_return_column },
329 { "cfi_restore", dot_cfi, DW_CFA_restore },
330 { "cfi_undefined", dot_cfi, DW_CFA_undefined },
331 { "cfi_same_value", dot_cfi, DW_CFA_same_value },
332 { "cfi_remember_state", dot_cfi, DW_CFA_remember_state },
333 { "cfi_restore_state", dot_cfi, DW_CFA_restore_state },
334 { "cfi_nop", dot_cfi, DW_CFA_nop },
339 cfi_parse_separator (void)
342 if (*input_line_pointer == ',')
343 input_line_pointer++;
345 as_bad (_("missing separator"));
354 #ifdef tc_regname_to_dw2regnum
356 if (is_name_beginner (*input_line_pointer)
357 || (*input_line_pointer == '%'
358 && is_name_beginner (*++input_line_pointer)))
362 name = input_line_pointer;
363 c = get_symbol_end ();
365 if ((regno = tc_regname_to_dw2regnum (name)) < 0)
367 as_bad (_("bad register expression"));
371 *input_line_pointer = c;
381 regno = exp.X_add_number;
385 as_bad (_("bad register expression"));
394 cfi_parse_const (void)
396 return get_absolute_expression ();
407 as_bad (_("CFI instruction used without previous .cfi_startproc"));
411 /* If the last address was not at the current PC, advance to current. */
412 if (symbol_get_frag (last_address) != frag_now
413 || S_GET_VALUE (last_address) != frag_now_fix ())
414 cfi_add_advance_loc (symbol_temp_new_now ());
419 reg1 = cfi_parse_reg ();
420 cfi_parse_separator ();
421 offset = cfi_parse_const ();
422 cfi_add_CFA_offset (reg1, offset);
426 reg1 = cfi_parse_reg ();
427 cfi_parse_separator ();
428 offset = cfi_parse_const ();
429 cfi_add_CFA_def_cfa (reg1, offset);
432 case DW_CFA_register:
433 reg1 = cfi_parse_reg ();
434 cfi_parse_separator ();
435 reg2 = cfi_parse_reg ();
436 cfi_add_CFA_register (reg1, reg2);
439 case DW_CFA_def_cfa_register:
440 reg1 = cfi_parse_reg ();
441 cfi_add_CFA_def_cfa_register (reg1);
444 case DW_CFA_def_cfa_offset:
445 offset = cfi_parse_const ();
446 cfi_add_CFA_def_cfa_offset (offset);
449 case CFI_adjust_cfa_offset:
450 offset = cfi_parse_const ();
451 cfi_add_CFA_def_cfa_offset (cur_cfa_offset + offset);
455 reg1 = cfi_parse_reg ();
456 cfi_add_CFA_restore (reg1);
459 case DW_CFA_undefined:
460 reg1 = cfi_parse_reg ();
461 cfi_add_CFA_undefined (reg1);
464 case DW_CFA_same_value:
465 reg1 = cfi_parse_reg ();
466 cfi_add_CFA_same_value (reg1);
469 case CFI_return_column:
470 reg1 = cfi_parse_reg ();
471 cfi_set_return_column (reg1);
474 case DW_CFA_remember_state:
475 cfi_add_CFA_remember_state ();
478 case DW_CFA_restore_state:
479 cfi_add_CFA_restore_state ();
490 demand_empty_rest_of_line ();
494 dot_cfi_startproc (int ignored ATTRIBUTE_UNUSED)
500 as_bad (_("previous CFI entry not closed (missing .cfi_endproc)"));
504 cfi_new_fde (symbol_temp_new_now ());
507 if (is_name_beginner (*input_line_pointer))
511 name = input_line_pointer;
512 c = get_symbol_end ();
514 if (strcmp (name, "simple") == 0)
517 *input_line_pointer = c;
520 input_line_pointer = name;
522 demand_empty_rest_of_line ();
525 tc_cfi_frame_initial_instructions ();
529 dot_cfi_endproc (int ignored ATTRIBUTE_UNUSED)
533 as_bad (_(".cfi_endproc without corresponding .cfi_startproc"));
537 cfi_end_fde (symbol_temp_new_now ());
541 /* Emit a single byte into the current segment. */
546 FRAG_APPEND_1_CHAR (byte);
549 /* Emit a two-byte word into the current segment. */
554 md_number_to_chars (frag_more (2), data, 2);
557 /* Emit a four byte word into the current segment. */
562 md_number_to_chars (frag_more (4), data, 4);
565 /* Emit an unsigned "little-endian base 128" number. */
568 out_uleb128 (addressT value)
570 output_leb128 (frag_more (sizeof_leb128 (value, 0)), value, 0);
573 /* Emit an unsigned "little-endian base 128" number. */
576 out_sleb128 (offsetT value)
578 output_leb128 (frag_more (sizeof_leb128 (value, 1)), value, 1);
582 output_cfi_insn (struct cfi_insn_data *insn)
589 case DW_CFA_advance_loc:
591 symbolS *from = insn->u.ll.lab1;
592 symbolS *to = insn->u.ll.lab2;
594 if (symbol_get_frag (to) == symbol_get_frag (from))
596 addressT delta = S_GET_VALUE (to) - S_GET_VALUE (from);
597 addressT scaled = delta / DWARF2_LINE_MIN_INSN_LENGTH;
600 out_one (DW_CFA_advance_loc + scaled);
601 else if (delta <= 0xFF)
603 out_one (DW_CFA_advance_loc1);
606 else if (delta <= 0xFFFF)
608 out_one (DW_CFA_advance_loc2);
613 out_one (DW_CFA_advance_loc4);
621 exp.X_op = O_subtract;
622 exp.X_add_symbol = to;
623 exp.X_op_symbol = from;
624 exp.X_add_number = 0;
626 /* The code in ehopt.c expects that one byte of the encoding
627 is already allocated to the frag. This comes from the way
628 that it scans the .eh_frame section looking first for the
629 .byte DW_CFA_advance_loc4. */
632 frag_var (rs_cfa, 4, 0, DWARF2_LINE_MIN_INSN_LENGTH << 3,
633 make_expr_symbol (&exp), frag_now_fix () - 1,
640 offset = insn->u.ri.offset;
643 out_one (DW_CFA_def_cfa_sf);
644 out_uleb128 (insn->u.ri.reg);
645 out_uleb128 (offset);
649 out_one (DW_CFA_def_cfa);
650 out_uleb128 (insn->u.ri.reg);
651 out_uleb128 (offset);
655 case DW_CFA_def_cfa_register:
656 case DW_CFA_undefined:
657 case DW_CFA_same_value:
658 out_one (insn->insn);
659 out_uleb128 (insn->u.r);
662 case DW_CFA_def_cfa_offset:
666 out_one (DW_CFA_def_cfa_offset_sf);
667 out_sleb128 (offset);
671 out_one (DW_CFA_def_cfa_offset);
672 out_uleb128 (offset);
680 out_one (DW_CFA_restore + regno);
684 out_one (DW_CFA_restore_extended);
690 regno = insn->u.ri.reg;
691 offset = insn->u.ri.offset / DWARF2_CIE_DATA_ALIGNMENT;
694 out_one (DW_CFA_offset_extended_sf);
696 out_sleb128 (offset);
698 else if (regno <= 0x3F)
700 out_one (DW_CFA_offset + regno);
701 out_uleb128 (offset);
705 out_one (DW_CFA_offset_extended);
707 out_uleb128 (offset);
711 case DW_CFA_register:
712 out_one (DW_CFA_register);
713 out_uleb128 (insn->u.rr.reg1);
714 out_uleb128 (insn->u.rr.reg2);
717 case DW_CFA_remember_state:
718 case DW_CFA_restore_state:
720 out_one (insn->insn);
729 output_cie (struct cie_entry *cie)
731 symbolS *after_size_address, *end_address;
733 struct cfi_insn_data *i;
735 cie->start_address = symbol_temp_new_now ();
736 after_size_address = symbol_temp_make ();
737 end_address = symbol_temp_make ();
739 exp.X_op = O_subtract;
740 exp.X_add_symbol = end_address;
741 exp.X_op_symbol = after_size_address;
742 exp.X_add_number = 0;
744 emit_expr (&exp, 4); /* Length */
745 symbol_set_value_now (after_size_address);
746 out_four (0); /* CIE id */
747 out_one (DW_CIE_VERSION); /* Version */
748 out_one ('z'); /* Augmentation */
751 out_uleb128 (DWARF2_LINE_MIN_INSN_LENGTH); /* Code alignment */
752 out_sleb128 (DWARF2_CIE_DATA_ALIGNMENT); /* Data alignment */
753 out_one (cie->return_column); /* Return column */
754 out_uleb128 (1); /* Augmentation size */
755 out_one (DW_EH_PE_pcrel | DW_EH_PE_sdata4);
758 for (i = cie->first; i != cie->last; i = i->next)
761 frag_align (2, 0, 0);
762 symbol_set_value_now (end_address);
766 output_fde (struct fde_entry *fde, struct cie_entry *cie,
767 struct cfi_insn_data *first)
769 symbolS *after_size_address, *end_address;
772 after_size_address = symbol_temp_make ();
773 end_address = symbol_temp_make ();
775 exp.X_op = O_subtract;
776 exp.X_add_symbol = end_address;
777 exp.X_op_symbol = after_size_address;
778 exp.X_add_number = 0;
779 emit_expr (&exp, 4); /* Length */
780 symbol_set_value_now (after_size_address);
782 exp.X_add_symbol = after_size_address;
783 exp.X_op_symbol = cie->start_address;
784 emit_expr (&exp, 4); /* CIE offset */
786 exp.X_add_symbol = fde->start_address;
787 exp.X_op_symbol = symbol_temp_new_now ();
788 emit_expr (&exp, 4); /* Code offset */
790 exp.X_add_symbol = fde->end_address;
791 exp.X_op_symbol = fde->start_address; /* Code length */
794 out_uleb128 (0); /* Augmentation size */
796 for (; first; first = first->next)
797 output_cfi_insn (first);
799 frag_align (2, 0, 0);
800 symbol_set_value_now (end_address);
803 static struct cie_entry *
804 select_cie_for_fde (struct fde_entry *fde, struct cfi_insn_data **pfirst)
806 struct cfi_insn_data *i, *j;
807 struct cie_entry *cie;
809 for (cie = cie_root; cie; cie = cie->next)
811 if (cie->return_column != fde->return_column)
813 for (i = cie->first, j = fde->data;
814 i != cie->last && j != NULL;
815 i = i->next, j = j->next)
817 if (i->insn != j->insn)
821 case DW_CFA_advance_loc:
822 /* We reached the first advance in the FDE, but did not
823 reach the end of the CIE list. */
828 if (i->u.ri.reg != j->u.ri.reg)
830 if (i->u.ri.offset != j->u.ri.offset)
834 case DW_CFA_register:
835 if (i->u.rr.reg1 != j->u.rr.reg1)
837 if (i->u.rr.reg2 != j->u.rr.reg2)
841 case DW_CFA_def_cfa_register:
843 case DW_CFA_undefined:
844 case DW_CFA_same_value:
845 if (i->u.r != j->u.r)
849 case DW_CFA_def_cfa_offset:
850 if (i->u.i != j->u.i)
859 /* Success if we reached the end of the CIE list, and we've either
860 run out of FDE entries or we've encountered an advance. */
861 if (i == cie->last && (!j || j->insn == DW_CFA_advance_loc))
870 cie = xmalloc (sizeof (struct cie_entry));
871 cie->next = cie_root;
873 cie->return_column = fde->return_column;
874 cie->first = fde->data;
876 for (i = cie->first; i ; i = i->next)
877 if (i->insn == DW_CFA_advance_loc)
892 struct fde_entry *fde;
893 int save_flag_traditional_format;
897 as_bad (_("open CFI at the end of file; missing .cfi_endproc directive"));
898 cur_fde_data->end_address = cur_fde_data->start_address;
901 if (all_fde_data == 0)
904 /* Open .eh_frame section. */
905 cfi_seg = subseg_new (".eh_frame", 0);
907 bfd_set_section_flags (stdoutput, cfi_seg,
908 SEC_ALLOC | SEC_LOAD | SEC_DATA | SEC_READONLY);
910 subseg_set (cfi_seg, 0);
911 record_alignment (cfi_seg, 2);
913 /* Make sure check_eh_frame doesn't do anything with our output. */
914 save_flag_traditional_format = flag_traditional_format;
915 flag_traditional_format = 1;
917 for (fde = all_fde_data; fde ; fde = fde->next)
919 struct cfi_insn_data *first;
920 struct cie_entry *cie;
922 cie = select_cie_for_fde (fde, &first);
923 output_fde (fde, cie, first);
926 flag_traditional_format = save_flag_traditional_format;