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binutils-gdb/gas/dwarf2dbg.c

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/* dwarf2dbg.c - DWARF2 debug support
Copyright (C) 1999, 2000 Free Software Foundation, Inc.
Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
This file is part of GAS, the GNU Assembler.
GAS is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
GAS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GAS; see the file COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
/* Logical line numbers can be controlled by the compiler via the
following two directives:
.file FILENO "file.c"
.loc FILENO LINENO [COLUMN]
FILENO is the filenumber. */
#include "ansidecl.h"
#include "as.h"
#include "dwarf2dbg.h"
#include "subsegs.h"
#include "elf/dwarf2.h"
/* Since we can't generate the prolog until the body is complete, we
use three different subsegments for .debug_line: one holding the
prolog, one for the directory and filename info, and one for the
body ("statement program"). */
#define DL_PROLOG 0
#define DL_FILES 1
#define DL_BODY 2
/* First special line opcde - leave room for the standard opcodes.
Note: If you want to change this, you'll have to update the
"standard_opcode_lengths" table that is emitted below in
dwarf2_finish(). */
#define DWARF2_LINE_OPCODE_BASE 10
#ifndef DWARF2_LINE_BASE
/* Minimum line offset in a special line info. opcode. This value
was chosen to give a reasonable range of values. */
# define DWARF2_LINE_BASE -5
#endif
/* Range of line offsets in a special line info. opcode. */
#ifndef DWARF2_LINE_RANGE
# define DWARF2_LINE_RANGE 14
#endif
#ifndef DWARF2_LINE_MIN_INSN_LENGTH
/* Define the architecture-dependent minimum instruction length (in
bytes). This value should be rather too small than too big. */
# define DWARF2_LINE_MIN_INSN_LENGTH 4
#endif
/* Flag that indicates the initial value of the is_stmt_start flag.
In the present implementation, we do not mark any lines as
the beginning of a source statement, because that information
is not made available by the GCC front-end. */
#define DWARF2_LINE_DEFAULT_IS_STMT 1
/* Flag that indicates the initial value of the is_stmt_start flag.
In the present implementation, we do not mark any lines as
the beginning of a source statement, because that information
is not made available by the GCC front-end. */
#define DWARF2_LINE_DEFAULT_IS_STMT 1
/* Given a special op, return the line skip amount. */
#define SPECIAL_LINE(op) \
(((op) - DWARF2_LINE_OPCODE_BASE)%DWARF2_LINE_RANGE + DWARF2_LINE_BASE)
/* Given a special op, return the address skip amount (in units of
DWARF2_LINE_MIN_INSN_LENGTH. */
#define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)
/* The maximum address skip amount that can be encoded with a special op. */
#define MAX_SPECIAL_ADDR_DELTA SPECIAL_ADDR(255)
#define INITIAL_STATE \
/* Initialize as per DWARF2.0 standard. */ \
0, /* address */ \
1, /* file */ \
1, /* line */ \
0, /* column */ \
DWARF2_LINE_DEFAULT_IS_STMT, /* is_stmt */ \
0, /* basic_block */ \
1 /* empty_sequence */
static struct
{
/* state machine state as per DWARF2 manual: */
struct dwarf2_sm
{
addressT addr;
unsigned int filenum;
unsigned int line;
unsigned int column;
unsigned int
is_stmt : 1,
basic_block : 1,
empty_sequence : 1; /* current code sequence has no DWARF2 directives? */
}
sm;
unsigned int
any_dwarf2_directives : 1; /* did we emit any DWARF2 line debug directives? */
fragS * frag; /* frag that "addr" is relative to */
segT text_seg; /* text segment "addr" is relative to */
subsegT text_subseg;
segT line_seg; /* ".debug_line" segment */
int last_filename; /* index of last filename that was used */
int num_filenames; /* index of last filename in use */
int filename_len; /* length of the filename array */
struct
{
int dir; /* valid after gen_dir_list() only */
char *name; /* full path before gen_dir_list(), filename afterwards */
}
*file;
struct dwarf2_line_info current; /* current source info: */
/* counters for statistical purposes: */
unsigned int num_line_entries;
unsigned int opcode_hist[256]; /* histogram of opcode frequencies */
}
ls =
{
{
INITIAL_STATE
},
0,
0,
0,
0,
0,
0,
0,
0,
NULL,
{ NULL, 0, 0, 0, 0 },
0,
{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
}
};
/* Function prototypes: */
static void out_uleb128 PARAMS ((addressT));
static void out_sleb128 PARAMS ((offsetT));
static void gen_addr_line PARAMS ((int, addressT));
static void reset_state_machine PARAMS ((void));
static void out_set_addr PARAMS ((addressT));
static void out_end_sequence PARAMS ((void));
static int get_filenum PARAMS ((int, char *));
static void gen_dir_list PARAMS ((void));
static void gen_file_list PARAMS ((void));
static void print_stats PARAMS ((unsigned long));
#define out_byte(byte) FRAG_APPEND_1_CHAR(byte)
#define out_opcode(opc) (out_byte ((opc)), ++ls.opcode_hist[(opc) & 0xff])
/* Output an unsigned "little-endian base 128" number. */
static void
out_uleb128 (value)
addressT value;
{
unsigned char byte, more = 0x80;
do
{
byte = value & 0x7f;
value >>= 7;
if (value == 0)
more = 0;
out_byte (more | byte);
}
while (more);
}
/* Output a signed "little-endian base 128" number. */
static void
out_sleb128 (value)
offsetT value;
{
unsigned char byte, more = 0x80;
do
{
byte = value & 0x7f;
value >>= 7;
if (((value == 0) && ((byte & 0x40) == 0))
|| ((value == -1) && ((byte & 0x40) != 0)))
more = 0;
out_byte (more | byte);
}
while (more);
}
/* Encode a pair of line and address skips as efficiently as possible.
Note that the line skip is signed, whereas the address skip is
unsigned. */
static void
gen_addr_line (line_delta, addr_delta)
int line_delta;
addressT addr_delta;
{
unsigned int tmp, opcode;
tmp = line_delta - DWARF2_LINE_BASE;
if (tmp >= DWARF2_LINE_RANGE)
{
out_opcode (DW_LNS_advance_line);
out_sleb128 (line_delta);
tmp = 0 - DWARF2_LINE_BASE;
line_delta = 0;
}
tmp += DWARF2_LINE_OPCODE_BASE;
/* try using a special opcode: */
opcode = tmp + addr_delta*DWARF2_LINE_RANGE;
if (opcode <= 255)
{
out_opcode (opcode);
return;
}
/* try using DW_LNS_const_add_pc followed by special op: */
opcode = tmp + (addr_delta - MAX_SPECIAL_ADDR_DELTA)*DWARF2_LINE_RANGE;
if (opcode <= 255)
{
out_opcode (DW_LNS_const_add_pc);
out_opcode (opcode);
return;
}
out_opcode (DW_LNS_advance_pc);
out_uleb128 (addr_delta);
if (line_delta)
out_opcode (tmp); /* output line-delta */
else
out_opcode (DW_LNS_copy); /* append new row with current info */
}
static void
reset_state_machine ()
{
static const struct dwarf2_sm initial_state = { INITIAL_STATE };
ls.sm = initial_state;
}
/* Set an absolute address (may results in a relocation entry): */
static void
out_set_addr (addr)
addressT addr;
{
subsegT saved_subseg;
segT saved_seg;
expressionS expr;
symbolS *sym;
int bytes_per_address;
saved_seg = now_seg;
saved_subseg = now_subseg;
subseg_set (ls.text_seg, ls.text_subseg);
sym = symbol_new (".L0\001", now_seg, addr, frag_now);
subseg_set (saved_seg, saved_subseg);
#ifdef BFD_ASSEMBLER
bytes_per_address = bfd_arch_bits_per_address (stdoutput) / 8;
#else
/* FIXME. */
bytes_per_address = 4;
#endif
out_opcode (DW_LNS_extended_op);
out_uleb128 (bytes_per_address + 1);
out_opcode (DW_LNE_set_address);
expr.X_op = O_symbol;
expr.X_add_symbol = sym;
expr.X_add_number = 0;
emit_expr (&expr, bytes_per_address);
}
/* Emit DW_LNS_end_sequence and reset state machine. Does not
preserve the current segment/sub-segment! */
static void
out_end_sequence ()
{
addressT addr, delta;
fragS *text_frag;
if (ls.text_seg)
{
subseg_set (ls.text_seg, ls.text_subseg);
#ifdef md_current_text_addr
addr = md_current_text_addr ();
#else
addr = frag_now_fix ();
#endif
text_frag = frag_now;
subseg_set (ls.line_seg, DL_BODY);
if (text_frag != ls.frag)
{
out_set_addr (addr);
ls.sm.addr = addr;
ls.frag = text_frag;
}
else
{
delta = (addr - ls.sm.addr) / DWARF2_LINE_MIN_INSN_LENGTH;
if (delta > 0)
{
/* Advance address without updating the line-debug
matrix---the end_sequence entry is used only to tell
the debugger the end of the sequence.*/
out_opcode (DW_LNS_advance_pc);
out_uleb128 (delta);
}
}
}
else
subseg_set (ls.line_seg, DL_BODY);
out_opcode (DW_LNS_extended_op);
out_uleb128 (1);
out_byte (DW_LNE_end_sequence);
reset_state_machine ();
}
/* Look up a filenumber either by filename or by filenumber. If both
a filenumber and a filename are specified, lookup by filename takes
precedence. If the filename cannot be found, it is added to the
filetable and the filenumber for the new entry is returned. */
static int
get_filenum (filenum, file)
int filenum;
char *file;
{
int i, last = filenum - 1;
char char0 = file[0];
/* If filenum is out of range of the filename table, then try using the
table entry returned from the previous call. */
if (last >= ls.num_filenames || last < 0)
last = ls.last_filename;
/* Do a quick check against the specified or previously used filenum. */
if (ls.num_filenames > 0 && ls.file[last].name[0] == char0
&& strcmp (ls.file[last].name + 1, file + 1) == 0)
return last + 1;
/* no match, fall back to simple linear scan: */
for (i = 0; i < ls.num_filenames; ++i)
{
if (ls.file[i].name[0] == char0
&& strcmp (ls.file[i].name + 1, file + 1) == 0)
{
ls.last_filename = i;
return i + 1;
}
}
/* no match: enter new filename */
if (ls.num_filenames >= ls.filename_len)
{
ls.filename_len += 13;
ls.file = xrealloc (ls.file, ls.filename_len * sizeof (ls.file[0]));
}
ls.file[ls.num_filenames].dir = 0;
ls.file[ls.num_filenames].name = file;
ls.last_filename = ls.num_filenames;
return ++ls.num_filenames;
}
/* Emit an entry in the line number table if the address or line has changed.
ADDR is relative to the current frag in the text section. */
void
dwarf2_gen_line_info (addr, l)
addressT addr;
struct dwarf2_line_info *l;
{
unsigned int filenum = l->filenum;
unsigned int any_output = 0;
subsegT saved_subseg;
segT saved_seg;
fragS *saved_frag;
if (flag_debug)
fprintf (stderr, "line: addr %lx file `%s' line %u col %u flags %x\n",
(unsigned long) addr, l->filename, l->line, l->column, l->flags);
if (filenum > 0 && !l->filename)
{
if (filenum >= (unsigned int) ls.num_filenames)
{
as_warn ("Encountered bad file number in line number debug info!");
return;
}
}
else if (l->filename)
filenum = get_filenum (filenum, l->filename);
else
return; /* no filename, no filnum => no play */
/* Must save these before the subseg_new call, as that call will change
them. */
saved_seg = now_seg;
saved_subseg = now_subseg;
saved_frag = frag_now;
if (!ls.line_seg)
{
#ifdef BFD_ASSEMBLER
symbolS *secsym;
#endif
ls.line_seg = subseg_new (".debug_line", 0);
#ifdef BFD_ASSEMBLER
bfd_set_section_flags (stdoutput, ls.line_seg, SEC_READONLY);
/* We're going to need this symbol. */
secsym = symbol_find (".debug_line");
if (secsym != NULL)
symbol_set_bfdsym (secsym, ls.line_seg->symbol);
else
symbol_table_insert (section_symbol (ls.line_seg));
#endif
}
subseg_set (ls.line_seg, DL_BODY);
if (ls.text_seg != saved_seg || ls.text_subseg != saved_subseg)
{
if (!ls.sm.empty_sequence)
{
out_end_sequence (); /* terminate previous sequence */
ls.sm.empty_sequence = 1;
}
any_output = 1;
ls.text_seg = saved_seg;
ls.text_subseg = saved_subseg;
out_set_addr (addr);
ls.sm.addr = addr;
ls.frag = saved_frag;
}
if (ls.sm.filenum != filenum)
{
any_output = 1;
out_opcode (DW_LNS_set_file);
out_uleb128 (filenum);
ls.sm.filenum = filenum;
}
if (ls.sm.column != l->column)
{
any_output = 1;
out_opcode (DW_LNS_set_column);
out_uleb128 (l->column);
ls.sm.column = l->column;
}
if (((l->flags & DWARF2_FLAG_BEGIN_STMT) != 0) != ls.sm.is_stmt)
{
any_output = 1;
out_opcode (DW_LNS_negate_stmt);
}
if (l->flags & DWARF2_FLAG_BEGIN_BLOCK)
{
any_output = 1;
out_opcode (DW_LNS_set_basic_block);
}
if (ls.sm.line != l->line)
{
any_output = 1;
if (saved_frag != ls.frag)
{
/* If a new frag got allocated (for whatever reason), then
deal with it by generating a reference symbol. Note: no
end_sequence needs to be generated because the address did
not really decrease (only the reference point changed). */
out_set_addr (addr);
ls.sm.addr = addr;
ls.frag = saved_frag;
}
gen_addr_line (l->line - ls.sm.line,
(addr - ls.sm.addr) / DWARF2_LINE_MIN_INSN_LENGTH);
ls.sm.basic_block = 0;
ls.sm.line = l->line;
ls.sm.addr = addr;
}
subseg_set (saved_seg, saved_subseg);
ls.num_line_entries += any_output;
if (any_output)
ls.sm.empty_sequence = 0;
}
static void
gen_dir_list ()
{
char *str, *slash, *dir_list, *dp, *cp;
int i, j, num_dirs;
dir_list = frag_more (0);
num_dirs = 0;
for (i = 0; i < ls.num_filenames; ++i)
{
str = ls.file[i].name;
slash = strrchr (str, '/');
if (slash)
{
*slash = '\0';
for (j = 0, dp = dir_list; j < num_dirs; ++j)
{
if (strcmp (str, dp) == 0)
{
ls.file[i].dir = j + 1;
break;
}
dp += strlen (dp);
}
if (j >= num_dirs)
{
/* didn't find this directory: append it to the list */
size_t size = strlen (str) + 1;
cp = frag_more (size);
memcpy (cp, str, size);
ls.file[i].dir = ++num_dirs;
}
*slash = '/';
ls.file[i].name = slash + 1;
}
}
out_byte ('\0'); /* terminate directory list */
}
static void
gen_file_list ()
{
size_t size;
char *cp;
int i;
for (i = 0; i < ls.num_filenames; ++i)
{
size = strlen (ls.file[i].name) + 1;
cp = frag_more (size);
memcpy (cp, ls.file[i].name, size);
out_uleb128 (ls.file[i].dir); /* directory number */
out_uleb128 (0); /* last modification timestamp */
out_uleb128 (0); /* filesize */
}
out_byte (0); /* terminate filename list */
}
static void
print_stats (total_size)
unsigned long total_size;
{
static const char *opc_name[] =
{
"extended", "copy", "advance_pc", "advance_line", "set_file",
"set_column", "negate_stmt", "set_basic_block", "const_add_pc",
"fixed_advance_pc"
};
size_t i;
int j;
fprintf (stderr, "Average size: %g bytes/line\n",
total_size / (double) ls.num_line_entries);
fprintf (stderr, "\nStandard opcode histogram:\n");
for (i = 0; i < sizeof (opc_name)/sizeof (opc_name[0]); ++i)
{
fprintf (stderr, "%s", opc_name[i]);
for (j = strlen (opc_name[i]); j < 16; ++j)
fprintf (stderr, " ");
fprintf (stderr, ": %u\n", ls.opcode_hist[i]);
}
fprintf (stderr, "\nSpecial opcodes:\naddr\t\t\t\tline skip\n");
fprintf (stderr, "skip: ");
for (j = DWARF2_LINE_BASE; j < DWARF2_LINE_BASE + DWARF2_LINE_RANGE; ++j)
fprintf (stderr, "%3d", j);
fprintf (stderr, "\n-----");
for (; i < 256; ++i)
{
j = SPECIAL_LINE (i);
if (j == DWARF2_LINE_BASE)
fprintf (stderr, "\n%4u: ",
((unsigned int)
DWARF2_LINE_MIN_INSN_LENGTH * SPECIAL_ADDR (i)));
fprintf (stderr, " %2u", ls.opcode_hist[i]);
}
fprintf (stderr, "\n");
}
void
dwarf2_finish ()
{
addressT body_size, total_size, prolog_size;
subsegT saved_subseg;
segT saved_seg;
char *cp;
if (!ls.line_seg)
/* no .debug_line segment, no work to do... */
return;
saved_seg = now_seg;
saved_subseg = now_subseg;
if (!ls.sm.empty_sequence)
out_end_sequence ();
total_size = body_size = frag_now_fix ();
/* now generate the directory and file lists: */
subseg_set (ls.line_seg, DL_FILES);
gen_dir_list ();
gen_file_list ();
total_size += frag_now_fix ();
/* and now the header ("statement program prolog", in DWARF2 lingo...) */
subseg_set (ls.line_seg, DL_PROLOG);
cp = frag_more (15 + DWARF2_LINE_OPCODE_BASE - 1);
total_size += frag_now_fix ();
prolog_size = total_size - body_size - 10;
# define STUFF(val,size) md_number_to_chars (cp, val, size); cp += size;
STUFF (total_size - 4, 4); /* length */
STUFF (2, 2); /* version */
STUFF (prolog_size, 4); /* prologue_length */
STUFF (DWARF2_LINE_MIN_INSN_LENGTH, 1);
STUFF (DWARF2_LINE_DEFAULT_IS_STMT, 1);
STUFF (DWARF2_LINE_BASE, 1);
STUFF (DWARF2_LINE_RANGE, 1);
STUFF (DWARF2_LINE_OPCODE_BASE, 1);
/* standard_opcode_lengths: */
STUFF (0, 1); /* DW_LNS_copy */
STUFF (1, 1); /* DW_LNS_advance_pc */
STUFF (1, 1); /* DW_LNS_advance_line */
STUFF (1, 1); /* DW_LNS_set_file */
STUFF (1, 1); /* DW_LNS_set_column */
STUFF (0, 1); /* DW_LNS_negate_stmt */
STUFF (0, 1); /* DW_LNS_set_basic_block */
STUFF (0, 1); /* DW_LNS_const_add_pc */
STUFF (1, 1); /* DW_LNS_fixed_advance_pc */
subseg_set (saved_seg, saved_subseg);
if (flag_debug)
print_stats (total_size);
}
void
dwarf2_directive_file (dummy)
int dummy ATTRIBUTE_UNUSED;
{
int len;
/* Continue to accept a bare string and pass it off. */
SKIP_WHITESPACE ();
if (*input_line_pointer == '"')
{
s_app_file (0);
return;
}
ls.any_dwarf2_directives = 1;
if (debug_type == DEBUG_NONE)
/* Automatically turn on DWARF2 debug info unless something else
has been selected. */
debug_type = DEBUG_DWARF2;
ls.current.filenum = get_absolute_expression ();
ls.current.filename = demand_copy_C_string (&len);
demand_empty_rest_of_line ();
}
void
dwarf2_directive_loc (dummy)
int dummy ATTRIBUTE_UNUSED;
{
ls.any_dwarf2_directives = 1;
ls.current.filenum = get_absolute_expression ();
SKIP_WHITESPACE ();
ls.current.line = get_absolute_expression ();
SKIP_WHITESPACE ();
ls.current.column = get_absolute_expression ();
demand_empty_rest_of_line ();
ls.current.flags = DWARF2_FLAG_BEGIN_STMT;
#ifndef NO_LISTING
if (listing)
listing_source_line (ls.current.line);
#endif
}
void
dwarf2_where (line)
struct dwarf2_line_info *line;
{
if (ls.any_dwarf2_directives)
*line = ls.current;
else
{
as_where (&line->filename, &line->line);
line->filenum = 0;
line->column = 0;
line->flags = DWARF2_FLAG_BEGIN_STMT;
}
}
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