gprof/symtab.c

/* symtab.c

   Copyright (C) 1999-2021 Free Software Foundation, Inc.

   This file is part of GNU Binutils.

   This program 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 3 of the License, or
   (at your option) any later version.

   This program 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 this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
   02110-1301, USA.  */

#include "gprof.h"
#include "search_list.h"
#include "source.h"
#include "symtab.h"
#include "cg_arcs.h"
#include "corefile.h"

static int cmp_addr (const PTR, const PTR);

Sym_Table symtab;


/* Initialize a symbol (so it's empty).  */

void
sym_init (Sym *sym)
{
  memset (sym, 0, sizeof (*sym));

  /* It is not safe to assume that a binary zero corresponds
     to a floating-point 0.0, so initialize floats explicitly.  */
  sym->hist.time = 0.0;
  sym->cg.child_time = 0.0;
  sym->cg.prop.fract = 0.0;
  sym->cg.prop.self = 0.0;
  sym->cg.prop.child = 0.0;
}


/* Compare the function entry-point of two symbols and return <0, =0,
   or >0 depending on whether the left value is smaller than, equal
   to, or greater than the right value.  If two symbols are equal
   but one has is_func set and the other doesn't, we make the
   non-function symbol one "bigger" so that the function symbol will
   survive duplicate removal.  Finally, if both symbols have the
   same is_func value, we discriminate against is_static such that
   the global symbol survives.  */

static int
cmp_addr (const PTR lp, const PTR rp)
{
  const Sym *left = (const Sym *) lp;
  const Sym *right = (const Sym *) rp;

  if (left->addr > right->addr)
    return 1;
  else if (left->addr < right->addr)
    return -1;

  if (left->is_func != right->is_func)
    return right->is_func - left->is_func;

  return left->is_static - right->is_static;
}


void
symtab_finalize (Sym_Table *tab)
{
  Sym *src, *dst;
  bfd_vma prev_addr;

  if (!tab->len)
    return;

  /* Sort symbol table in order of increasing function addresses.  */
  qsort (tab->base, tab->len, sizeof (Sym), cmp_addr);

  /* Remove duplicate entries to speed-up later processing and
     set end_addr if its not set yet.  */
  prev_addr = tab->base[0].addr - 1;

  for (src = dst = tab->base; src < tab->limit; ++src)
    {
      if (src->addr == prev_addr)
	{
	  /* If same address, favor global symbol over static one,
	     then function over line number.  If both symbols are
	     either static or global and either function or line, check
	     whether one has name beginning with underscore while
	     the other doesn't.  In such cases, keep sym without
	     underscore.  This takes cares of compiler generated
	     symbols (such as __gnu_compiled, __c89_used, etc.).  */
	  if ((!src->is_static && dst[-1].is_static)
	      || ((src->is_static == dst[-1].is_static)
		  && ((src->is_func && !dst[-1].is_func)
		      || ((src->is_func == dst[-1].is_func)
			  && ((src->name[0] != '_' && dst[-1].name[0] == '_')
			      || (src->name[0] == '_' && dst[-1].name[0] == '_'
				  && src->name[1] != '_'
				  && dst[-1].name[1] == '_'))))))
	    {
	      DBG (AOUTDEBUG | IDDEBUG,
		   printf ("[symtab_finalize] favor %s@%c%c over %s@%c%c",
			   src->name, src->is_static ? 't' : 'T',
			   src->is_func ? 'F' : 'f',
			   dst[-1].name, dst[-1].is_static ? 't' : 'T',
			   dst[-1].is_func ? 'F' : 'f');
		   printf (" (addr=%lx)\n", (unsigned long) src->addr));

	      dst[-1] = *src;
	    }
	  else
	    {
	      DBG (AOUTDEBUG | IDDEBUG,
		   printf ("[symtab_finalize] favor %s@%c%c over %s@%c%c",
			   dst[-1].name, dst[-1].is_static ? 't' : 'T',
			   dst[-1].is_func ? 'F' : 'f',
			   src->name, src->is_static ? 't' : 'T',
			   src->is_func ? 'F' : 'f');
		   printf (" (addr=%lx)\n", (unsigned long) src->addr));
	    }
	}
      else
	{
	  if (dst > tab->base && dst[-1].end_addr == 0)
	    dst[-1].end_addr = src->addr - 1;

	  /* Retain sym only if it has a non-empty address range.  */
	  if (!src->end_addr || src->addr <= src->end_addr)
	    {
	      *dst = *src;
	      dst++;
	      prev_addr = src->addr;
	    }
	}
    }

  if (tab->len > 0 && dst[-1].end_addr == 0)
    dst[-1].end_addr
      = core_text_sect->vma + bfd_section_size (core_text_sect) - 1;

  DBG (AOUTDEBUG | IDDEBUG,
       printf ("[symtab_finalize]: removed %d duplicate entries\n",
	       tab->len - (int) (dst - tab->base)));

  tab->limit = dst;
  tab->len = tab->limit - tab->base;

  DBG (AOUTDEBUG | IDDEBUG,
       unsigned int j;

       for (j = 0; j < tab->len; ++j)
	 {
	   printf ("[symtab_finalize] 0x%lx-0x%lx\t%s\n",
		   (unsigned long) tab->base[j].addr,
		   (unsigned long) tab->base[j].end_addr,
		   tab->base[j].name);
	 }
  );
}


#ifdef DEBUG

Sym *
dbg_sym_lookup (Sym_Table *sym_tab, bfd_vma address)
{
  unsigned long low, mid, high;
  Sym *sym;

  fprintf (stderr, "[dbg_sym_lookup] address 0x%lx\n",
	   (unsigned long) address);

  sym = sym_tab->base;
  for (low = 0, high = sym_tab->len - 1; low != high;)
    {
      mid = (high + low) >> 1;

      fprintf (stderr, "[dbg_sym_lookup] low=0x%lx, mid=0x%lx, high=0x%lx\n",
	       low, mid, high);
      fprintf (stderr, "[dbg_sym_lookup] sym[m]=0x%lx sym[m + 1]=0x%lx\n",
	       (unsigned long) sym[mid].addr,
	       (unsigned long) sym[mid + 1].addr);

      if (sym[mid].addr <= address && sym[mid + 1].addr > address)
	return &sym[mid];

      if (sym[mid].addr > address)
	high = mid;
      else
	low = mid + 1;
    }

  fprintf (stderr, "[dbg_sym_lookup] binary search fails???\n");

  return 0;
}

#endif	/* DEBUG */


/* Look up an address in the symbol-table that is sorted by address.
   If address does not hit any symbol, 0 is returned.  */
Sym *
sym_lookup (Sym_Table *sym_tab, bfd_vma address)
{
  long low, high;
  long mid = -1;
  Sym *sym;
#ifdef DEBUG
  int probes = 0;
#endif /* DEBUG */

  if (!sym_tab->len)
    return 0;

  sym = sym_tab->base;
  for (low = 0, high = sym_tab->len - 1; low != high;)
    {
      DBG (LOOKUPDEBUG, ++probes);
      mid = (high + low) / 2;

      if (sym[mid].addr <= address && sym[mid + 1].addr > address)
	{
	  if (address > sym[mid].end_addr)
	    {
	      /* Address falls into gap between
		 sym[mid] and sym[mid + 1].  */
	      return 0;
	    }
	  else
	    {
	      DBG (LOOKUPDEBUG,
		   printf ("[sym_lookup] %d probes (symtab->len=%u)\n",
			   probes, sym_tab->len - 1));
	      return &sym[mid];
	    }
	}

      if (sym[mid].addr > address)
	high = mid;
      else
	low = mid + 1;
    }

  if (sym[mid + 1].addr <= address)
    {
      if (address > sym[mid + 1].end_addr)
	{
	  /* Address is beyond end of sym[mid + 1].  */
	  return 0;
	}
      else
	{
	  DBG (LOOKUPDEBUG, printf ("[sym_lookup] %d (%u) probes, fall off\n",
				    probes, sym_tab->len - 1));
	  return &sym[mid + 1];
	}
    }

  return 0;
}