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 EH_FRAME_ALIGNMENT
46 # define EH_FRAME_ALIGNMENT (bfd_get_arch_size (stdoutput) == 64 ? 3 : 2)
48 # define EH_FRAME_ALIGNMENT 2
52 #ifndef tc_cfi_frame_initial_instructions
53 # define tc_cfi_frame_initial_instructions() ((void)0)
59 struct cfi_insn_data *next;
80 struct cfi_escape_data {
81 struct cfi_escape_data *next;
89 struct fde_entry *next;
90 symbolS *start_address;
92 struct cfi_insn_data *data;
93 struct cfi_insn_data **last;
94 unsigned int return_column;
99 struct cie_entry *next;
100 symbolS *start_address;
101 unsigned int return_column;
102 struct cfi_insn_data *first, *last;
106 /* Current open FDE entry. */
107 static struct fde_entry *cur_fde_data;
108 static symbolS *last_address;
109 static offsetT cur_cfa_offset;
111 /* List of FDE entries. */
112 static struct fde_entry *all_fde_data;
113 static struct fde_entry **last_fde_data = &all_fde_data;
115 /* List of CIEs so that they could be reused. */
116 static struct cie_entry *cie_root;
118 /* Stack of old CFI data, for save/restore. */
121 struct cfa_save_data *next;
125 static struct cfa_save_data *cfa_save_stack;
127 /* Construct a new FDE structure and add it to the end of the fde list. */
129 static struct fde_entry *
130 alloc_fde_entry (void)
132 struct fde_entry *fde = xcalloc (1, sizeof (struct fde_entry));
135 *last_fde_data = fde;
136 last_fde_data = &fde->next;
138 fde->last = &fde->data;
139 fde->return_column = DWARF2_DEFAULT_RETURN_COLUMN;
144 /* The following functions are available for a backend to construct its
145 own unwind information, usually from legacy unwind directives. */
147 /* Construct a new INSN structure and add it to the end of the insn list
148 for the currently active FDE. */
150 static struct cfi_insn_data *
151 alloc_cfi_insn_data (void)
153 struct cfi_insn_data *insn = xcalloc (1, sizeof (struct cfi_insn_data));
155 *cur_fde_data->last = insn;
156 cur_fde_data->last = &insn->next;
161 /* Construct a new FDE structure that begins at LABEL. */
164 cfi_new_fde (symbolS *label)
166 struct fde_entry *fde = alloc_fde_entry ();
167 fde->start_address = label;
168 last_address = label;
171 /* End the currently open FDE. */
174 cfi_end_fde (symbolS *label)
176 cur_fde_data->end_address = label;
180 /* Set the return column for the current FDE. */
183 cfi_set_return_column (unsigned regno)
185 cur_fde_data->return_column = regno;
188 /* Universal functions to store new instructions. */
191 cfi_add_CFA_insn(int insn)
193 struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
195 insn_ptr->insn = insn;
199 cfi_add_CFA_insn_reg (int insn, unsigned regno)
201 struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
203 insn_ptr->insn = insn;
204 insn_ptr->u.r = regno;
208 cfi_add_CFA_insn_offset (int insn, offsetT offset)
210 struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
212 insn_ptr->insn = insn;
213 insn_ptr->u.i = offset;
217 cfi_add_CFA_insn_reg_reg (int insn, unsigned reg1, unsigned reg2)
219 struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
221 insn_ptr->insn = insn;
222 insn_ptr->u.rr.reg1 = reg1;
223 insn_ptr->u.rr.reg2 = reg2;
227 cfi_add_CFA_insn_reg_offset (int insn, unsigned regno, offsetT offset)
229 struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
231 insn_ptr->insn = insn;
232 insn_ptr->u.ri.reg = regno;
233 insn_ptr->u.ri.offset = offset;
236 /* Add a CFI insn to advance the PC from the last address to LABEL. */
239 cfi_add_advance_loc (symbolS *label)
241 struct cfi_insn_data *insn = alloc_cfi_insn_data ();
243 insn->insn = DW_CFA_advance_loc;
244 insn->u.ll.lab1 = last_address;
245 insn->u.ll.lab2 = label;
247 last_address = label;
250 /* Add a DW_CFA_offset record to the CFI data. */
253 cfi_add_CFA_offset (unsigned regno, offsetT offset)
255 unsigned int abs_data_align;
257 cfi_add_CFA_insn_reg_offset (DW_CFA_offset, regno, offset);
259 abs_data_align = (DWARF2_CIE_DATA_ALIGNMENT < 0
260 ? -DWARF2_CIE_DATA_ALIGNMENT : DWARF2_CIE_DATA_ALIGNMENT);
261 if (offset % abs_data_align)
262 as_bad (_("register save offset not a multiple of %u"), abs_data_align);
265 /* Add a DW_CFA_def_cfa record to the CFI data. */
268 cfi_add_CFA_def_cfa (unsigned regno, offsetT offset)
270 cfi_add_CFA_insn_reg_offset (DW_CFA_def_cfa, regno, offset);
271 cur_cfa_offset = offset;
274 /* Add a DW_CFA_register record to the CFI data. */
277 cfi_add_CFA_register (unsigned reg1, unsigned reg2)
279 cfi_add_CFA_insn_reg_reg (DW_CFA_register, reg1, reg2);
282 /* Add a DW_CFA_def_cfa_register record to the CFI data. */
285 cfi_add_CFA_def_cfa_register (unsigned regno)
287 cfi_add_CFA_insn_reg (DW_CFA_def_cfa_register, regno);
290 /* Add a DW_CFA_def_cfa_offset record to the CFI data. */
293 cfi_add_CFA_def_cfa_offset (offsetT offset)
295 cfi_add_CFA_insn_offset (DW_CFA_def_cfa_offset, offset);
296 cur_cfa_offset = offset;
300 cfi_add_CFA_restore (unsigned regno)
302 cfi_add_CFA_insn_reg (DW_CFA_restore, regno);
306 cfi_add_CFA_undefined (unsigned regno)
308 cfi_add_CFA_insn_reg (DW_CFA_undefined, regno);
312 cfi_add_CFA_same_value (unsigned regno)
314 cfi_add_CFA_insn_reg (DW_CFA_same_value, regno);
318 cfi_add_CFA_remember_state (void)
320 struct cfa_save_data *p;
322 cfi_add_CFA_insn (DW_CFA_remember_state);
324 p = xmalloc (sizeof (*p));
325 p->cfa_offset = cur_cfa_offset;
326 p->next = cfa_save_stack;
331 cfi_add_CFA_restore_state (void)
333 struct cfa_save_data *p;
335 cfi_add_CFA_insn (DW_CFA_restore_state);
340 cur_cfa_offset = p->cfa_offset;
341 cfa_save_stack = p->next;
347 /* Parse CFI assembler directives. */
349 static void dot_cfi (int);
350 static void dot_cfi_escape (int);
351 static void dot_cfi_startproc (int);
352 static void dot_cfi_endproc (int);
354 /* Fake CFI type; outside the byte range of any real CFI insn. */
355 #define CFI_adjust_cfa_offset 0x100
356 #define CFI_return_column 0x101
357 #define CFI_rel_offset 0x102
358 #define CFI_escape 0x103
360 const pseudo_typeS cfi_pseudo_table[] =
362 { "cfi_startproc", dot_cfi_startproc, 0 },
363 { "cfi_endproc", dot_cfi_endproc, 0 },
364 { "cfi_def_cfa", dot_cfi, DW_CFA_def_cfa },
365 { "cfi_def_cfa_register", dot_cfi, DW_CFA_def_cfa_register },
366 { "cfi_def_cfa_offset", dot_cfi, DW_CFA_def_cfa_offset },
367 { "cfi_adjust_cfa_offset", dot_cfi, CFI_adjust_cfa_offset },
368 { "cfi_offset", dot_cfi, DW_CFA_offset },
369 { "cfi_rel_offset", dot_cfi, CFI_rel_offset },
370 { "cfi_register", dot_cfi, DW_CFA_register },
371 { "cfi_return_column", dot_cfi, CFI_return_column },
372 { "cfi_restore", dot_cfi, DW_CFA_restore },
373 { "cfi_undefined", dot_cfi, DW_CFA_undefined },
374 { "cfi_same_value", dot_cfi, DW_CFA_same_value },
375 { "cfi_remember_state", dot_cfi, DW_CFA_remember_state },
376 { "cfi_restore_state", dot_cfi, DW_CFA_restore_state },
377 { "cfi_escape", dot_cfi_escape, 0 },
382 cfi_parse_separator (void)
385 if (*input_line_pointer == ',')
386 input_line_pointer++;
388 as_bad (_("missing separator"));
397 #ifdef tc_regname_to_dw2regnum
399 if (is_name_beginner (*input_line_pointer)
400 || (*input_line_pointer == '%'
401 && is_name_beginner (*++input_line_pointer)))
405 name = input_line_pointer;
406 c = get_symbol_end ();
408 if ((regno = tc_regname_to_dw2regnum (name)) < 0)
410 as_bad (_("bad register expression"));
414 *input_line_pointer = c;
424 regno = exp.X_add_number;
428 as_bad (_("bad register expression"));
437 cfi_parse_const (void)
439 return get_absolute_expression ();
450 as_bad (_("CFI instruction used without previous .cfi_startproc"));
454 /* If the last address was not at the current PC, advance to current. */
455 if (symbol_get_frag (last_address) != frag_now
456 || S_GET_VALUE (last_address) != frag_now_fix ())
457 cfi_add_advance_loc (symbol_temp_new_now ());
462 reg1 = cfi_parse_reg ();
463 cfi_parse_separator ();
464 offset = cfi_parse_const ();
465 cfi_add_CFA_offset (reg1, offset);
469 reg1 = cfi_parse_reg ();
470 cfi_parse_separator ();
471 offset = cfi_parse_const ();
472 cfi_add_CFA_offset (reg1, offset - cur_cfa_offset);
476 reg1 = cfi_parse_reg ();
477 cfi_parse_separator ();
478 offset = cfi_parse_const ();
479 cfi_add_CFA_def_cfa (reg1, offset);
482 case DW_CFA_register:
483 reg1 = cfi_parse_reg ();
484 cfi_parse_separator ();
485 reg2 = cfi_parse_reg ();
486 cfi_add_CFA_register (reg1, reg2);
489 case DW_CFA_def_cfa_register:
490 reg1 = cfi_parse_reg ();
491 cfi_add_CFA_def_cfa_register (reg1);
494 case DW_CFA_def_cfa_offset:
495 offset = cfi_parse_const ();
496 cfi_add_CFA_def_cfa_offset (offset);
499 case CFI_adjust_cfa_offset:
500 offset = cfi_parse_const ();
501 cfi_add_CFA_def_cfa_offset (cur_cfa_offset + offset);
505 reg1 = cfi_parse_reg ();
506 cfi_add_CFA_restore (reg1);
509 case DW_CFA_undefined:
510 reg1 = cfi_parse_reg ();
511 cfi_add_CFA_undefined (reg1);
514 case DW_CFA_same_value:
515 reg1 = cfi_parse_reg ();
516 cfi_add_CFA_same_value (reg1);
519 case CFI_return_column:
520 reg1 = cfi_parse_reg ();
521 cfi_set_return_column (reg1);
524 case DW_CFA_remember_state:
525 cfi_add_CFA_remember_state ();
528 case DW_CFA_restore_state:
529 cfi_add_CFA_restore_state ();
536 demand_empty_rest_of_line ();
540 dot_cfi_escape (int ignored ATTRIBUTE_UNUSED)
542 struct cfi_escape_data *head, **tail, *e;
543 struct cfi_insn_data *insn;
547 as_bad (_("CFI instruction used without previous .cfi_startproc"));
551 /* If the last address was not at the current PC, advance to current. */
552 if (symbol_get_frag (last_address) != frag_now
553 || S_GET_VALUE (last_address) != frag_now_fix ())
554 cfi_add_advance_loc (symbol_temp_new_now ());
559 e = xmalloc (sizeof (*e));
560 do_parse_cons_expression (&e->exp, 1);
564 while (*input_line_pointer++ == ',');
567 insn = alloc_cfi_insn_data ();
568 insn->insn = CFI_escape;
573 dot_cfi_startproc (int ignored ATTRIBUTE_UNUSED)
579 as_bad (_("previous CFI entry not closed (missing .cfi_endproc)"));
583 cfi_new_fde (symbol_temp_new_now ());
586 if (is_name_beginner (*input_line_pointer))
590 name = input_line_pointer;
591 c = get_symbol_end ();
593 if (strcmp (name, "simple") == 0)
596 *input_line_pointer = c;
599 input_line_pointer = name;
601 demand_empty_rest_of_line ();
604 tc_cfi_frame_initial_instructions ();
608 dot_cfi_endproc (int ignored ATTRIBUTE_UNUSED)
612 as_bad (_(".cfi_endproc without corresponding .cfi_startproc"));
616 cfi_end_fde (symbol_temp_new_now ());
620 /* Emit a single byte into the current segment. */
625 FRAG_APPEND_1_CHAR (byte);
628 /* Emit a two-byte word into the current segment. */
633 md_number_to_chars (frag_more (2), data, 2);
636 /* Emit a four byte word into the current segment. */
641 md_number_to_chars (frag_more (4), data, 4);
644 /* Emit an unsigned "little-endian base 128" number. */
647 out_uleb128 (addressT value)
649 output_leb128 (frag_more (sizeof_leb128 (value, 0)), value, 0);
652 /* Emit an unsigned "little-endian base 128" number. */
655 out_sleb128 (offsetT value)
657 output_leb128 (frag_more (sizeof_leb128 (value, 1)), value, 1);
661 output_cfi_insn (struct cfi_insn_data *insn)
668 case DW_CFA_advance_loc:
670 symbolS *from = insn->u.ll.lab1;
671 symbolS *to = insn->u.ll.lab2;
673 if (symbol_get_frag (to) == symbol_get_frag (from))
675 addressT delta = S_GET_VALUE (to) - S_GET_VALUE (from);
676 addressT scaled = delta / DWARF2_LINE_MIN_INSN_LENGTH;
679 out_one (DW_CFA_advance_loc + scaled);
680 else if (delta <= 0xFF)
682 out_one (DW_CFA_advance_loc1);
685 else if (delta <= 0xFFFF)
687 out_one (DW_CFA_advance_loc2);
692 out_one (DW_CFA_advance_loc4);
700 exp.X_op = O_subtract;
701 exp.X_add_symbol = to;
702 exp.X_op_symbol = from;
703 exp.X_add_number = 0;
705 /* The code in ehopt.c expects that one byte of the encoding
706 is already allocated to the frag. This comes from the way
707 that it scans the .eh_frame section looking first for the
708 .byte DW_CFA_advance_loc4. */
711 frag_var (rs_cfa, 4, 0, DWARF2_LINE_MIN_INSN_LENGTH << 3,
712 make_expr_symbol (&exp), frag_now_fix () - 1,
719 offset = insn->u.ri.offset;
722 out_one (DW_CFA_def_cfa_sf);
723 out_uleb128 (insn->u.ri.reg);
724 out_uleb128 (offset);
728 out_one (DW_CFA_def_cfa);
729 out_uleb128 (insn->u.ri.reg);
730 out_uleb128 (offset);
734 case DW_CFA_def_cfa_register:
735 case DW_CFA_undefined:
736 case DW_CFA_same_value:
737 out_one (insn->insn);
738 out_uleb128 (insn->u.r);
741 case DW_CFA_def_cfa_offset:
745 out_one (DW_CFA_def_cfa_offset_sf);
746 out_sleb128 (offset);
750 out_one (DW_CFA_def_cfa_offset);
751 out_uleb128 (offset);
759 out_one (DW_CFA_restore + regno);
763 out_one (DW_CFA_restore_extended);
769 regno = insn->u.ri.reg;
770 offset = insn->u.ri.offset / DWARF2_CIE_DATA_ALIGNMENT;
773 out_one (DW_CFA_offset_extended_sf);
775 out_sleb128 (offset);
777 else if (regno <= 0x3F)
779 out_one (DW_CFA_offset + regno);
780 out_uleb128 (offset);
784 out_one (DW_CFA_offset_extended);
786 out_uleb128 (offset);
790 case DW_CFA_register:
791 out_one (DW_CFA_register);
792 out_uleb128 (insn->u.rr.reg1);
793 out_uleb128 (insn->u.rr.reg2);
796 case DW_CFA_remember_state:
797 case DW_CFA_restore_state:
798 out_one (insn->insn);
803 struct cfi_escape_data *e;
804 for (e = insn->u.esc; e ; e = e->next)
805 emit_expr (&e->exp, 1);
815 output_cie (struct cie_entry *cie)
817 symbolS *after_size_address, *end_address;
819 struct cfi_insn_data *i;
821 cie->start_address = symbol_temp_new_now ();
822 after_size_address = symbol_temp_make ();
823 end_address = symbol_temp_make ();
825 exp.X_op = O_subtract;
826 exp.X_add_symbol = end_address;
827 exp.X_op_symbol = after_size_address;
828 exp.X_add_number = 0;
830 emit_expr (&exp, 4); /* Length */
831 symbol_set_value_now (after_size_address);
832 out_four (0); /* CIE id */
833 out_one (DW_CIE_VERSION); /* Version */
834 out_one ('z'); /* Augmentation */
837 out_uleb128 (DWARF2_LINE_MIN_INSN_LENGTH); /* Code alignment */
838 out_sleb128 (DWARF2_CIE_DATA_ALIGNMENT); /* Data alignment */
839 out_one (cie->return_column); /* Return column */
840 out_uleb128 (1); /* Augmentation size */
841 out_one (DW_EH_PE_pcrel | DW_EH_PE_sdata4);
844 for (i = cie->first; i != cie->last; i = i->next)
847 symbol_set_value_now (end_address);
851 output_fde (struct fde_entry *fde, struct cie_entry *cie,
852 struct cfi_insn_data *first, int align)
854 symbolS *after_size_address, *end_address;
857 after_size_address = symbol_temp_make ();
858 end_address = symbol_temp_make ();
860 exp.X_op = O_subtract;
861 exp.X_add_symbol = end_address;
862 exp.X_op_symbol = after_size_address;
863 exp.X_add_number = 0;
864 emit_expr (&exp, 4); /* Length */
865 symbol_set_value_now (after_size_address);
867 exp.X_add_symbol = after_size_address;
868 exp.X_op_symbol = cie->start_address;
869 emit_expr (&exp, 4); /* CIE offset */
871 exp.X_add_symbol = fde->start_address;
872 exp.X_op_symbol = symbol_temp_new_now ();
873 emit_expr (&exp, 4); /* Code offset */
875 exp.X_add_symbol = fde->end_address;
876 exp.X_op_symbol = fde->start_address; /* Code length */
879 out_uleb128 (0); /* Augmentation size */
881 for (; first; first = first->next)
882 output_cfi_insn (first);
885 frag_align (align, 0, 0);
886 symbol_set_value_now (end_address);
889 static struct cie_entry *
890 select_cie_for_fde (struct fde_entry *fde, struct cfi_insn_data **pfirst)
892 struct cfi_insn_data *i, *j;
893 struct cie_entry *cie;
895 for (cie = cie_root; cie; cie = cie->next)
897 if (cie->return_column != fde->return_column)
899 for (i = cie->first, j = fde->data;
900 i != cie->last && j != NULL;
901 i = i->next, j = j->next)
903 if (i->insn != j->insn)
907 case DW_CFA_advance_loc:
908 /* We reached the first advance in the FDE, but did not
909 reach the end of the CIE list. */
914 if (i->u.ri.reg != j->u.ri.reg)
916 if (i->u.ri.offset != j->u.ri.offset)
920 case DW_CFA_register:
921 if (i->u.rr.reg1 != j->u.rr.reg1)
923 if (i->u.rr.reg2 != j->u.rr.reg2)
927 case DW_CFA_def_cfa_register:
929 case DW_CFA_undefined:
930 case DW_CFA_same_value:
931 if (i->u.r != j->u.r)
935 case DW_CFA_def_cfa_offset:
936 if (i->u.i != j->u.i)
941 /* Don't bother matching these for now. */
949 /* Success if we reached the end of the CIE list, and we've either
950 run out of FDE entries or we've encountered an advance. */
951 if (i == cie->last && (!j || j->insn == DW_CFA_advance_loc))
960 cie = xmalloc (sizeof (struct cie_entry));
961 cie->next = cie_root;
963 cie->return_column = fde->return_column;
964 cie->first = fde->data;
966 for (i = cie->first; i ; i = i->next)
967 if (i->insn == DW_CFA_advance_loc)
982 struct fde_entry *fde;
983 int save_flag_traditional_format;
987 as_bad (_("open CFI at the end of file; missing .cfi_endproc directive"));
988 cur_fde_data->end_address = cur_fde_data->start_address;
991 if (all_fde_data == 0)
994 /* Open .eh_frame section. */
995 cfi_seg = subseg_new (".eh_frame", 0);
997 bfd_set_section_flags (stdoutput, cfi_seg,
998 SEC_ALLOC | SEC_LOAD | SEC_DATA | SEC_READONLY);
1000 subseg_set (cfi_seg, 0);
1001 record_alignment (cfi_seg, EH_FRAME_ALIGNMENT);
1003 /* Make sure check_eh_frame doesn't do anything with our output. */
1004 save_flag_traditional_format = flag_traditional_format;
1005 flag_traditional_format = 1;
1007 for (fde = all_fde_data; fde ; fde = fde->next)
1009 struct cfi_insn_data *first;
1010 struct cie_entry *cie;
1012 cie = select_cie_for_fde (fde, &first);
1013 output_fde (fde, cie, first, fde->next == NULL ? EH_FRAME_ALIGNMENT : 0);
1016 flag_traditional_format = save_flag_traditional_format;