diff --git a/libdwfl/segment.c b/libdwfl/segment.c
new file mode 100644
index 0000000..3c1f8bc
--- /dev/null
+++ b/libdwfl/segment.c
@@ -0,0 +1,300 @@
+/* Manage address space lookup table for libdwfl.
+   Copyright (C) 2008 Red Hat, Inc.
+   This file is part of Red Hat elfutils.
+
+   Red Hat elfutils 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; version 2 of the License.
+
+   Red Hat elfutils 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 Red Hat elfutils; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
+
+   In addition, as a special exception, Red Hat, Inc. gives You the
+   additional right to link the code of Red Hat elfutils with code licensed
+   under any Open Source Initiative certified open source license
+   (http://www.opensource.org/licenses/index.php) which requires the
+   distribution of source code with any binary distribution and to
+   distribute linked combinations of the two.  Non-GPL Code permitted under
+   this exception must only link to the code of Red Hat elfutils through
+   those well defined interfaces identified in the file named EXCEPTION
+   found in the source code files (the "Approved Interfaces").  The files
+   of Non-GPL Code may instantiate templates or use macros or inline
+   functions from the Approved Interfaces without causing the resulting
+   work to be covered by the GNU General Public License.  Only Red Hat,
+   Inc. may make changes or additions to the list of Approved Interfaces.
+   Red Hat's grant of this exception is conditioned upon your not adding
+   any new exceptions.  If you wish to add a new Approved Interface or
+   exception, please contact Red Hat.  You must obey the GNU General Public
+   License in all respects for all of the Red Hat elfutils code and other
+   code used in conjunction with Red Hat elfutils except the Non-GPL Code
+   covered by this exception.  If you modify this file, you may extend this
+   exception to your version of the file, but you are not obligated to do
+   so.  If you do not wish to provide this exception without modification,
+   you must delete this exception statement from your version and license
+   this file solely under the GPL without exception.
+
+   Red Hat elfutils is an included package of the Open Invention Network.
+   An included package of the Open Invention Network is a package for which
+   Open Invention Network licensees cross-license their patents.  No patent
+   license is granted, either expressly or impliedly, by designation as an
+   included package.  Should you wish to participate in the Open Invention
+   Network licensing program, please visit www.openinventionnetwork.com
+   <http://www.openinventionnetwork.com>.  */
+
+#include "libdwflP.h"
+
+static GElf_Addr
+segment_start (Dwfl *dwfl, GElf_Addr start)
+{
+  if (dwfl->segment_align > 1)
+    start &= -dwfl->segment_align;
+  return start;
+}
+
+static GElf_Addr
+segment_end (Dwfl *dwfl, GElf_Addr end)
+{
+  if (dwfl->segment_align > 1)
+    end = (end + dwfl->segment_align - 1) & -dwfl->segment_align;
+  return end;
+}
+
+static bool
+insert (Dwfl *dwfl, size_t i, GElf_Addr start, GElf_Addr end, int segndx)
+{
+  bool need_start = (i == 0 || dwfl->lookup_addr[i - 1] != start);
+  bool need_end = (i >= dwfl->lookup_elts || dwfl->lookup_addr[i + 1] != end);
+  size_t need = need_start + need_end;
+  if (need == 0)
+    return false;
+
+  if (dwfl->lookup_alloc - dwfl->lookup_elts < need)
+    {
+      size_t n = dwfl->lookup_alloc == 0 ? 16 : dwfl->lookup_alloc * 2;
+      GElf_Addr *naddr = realloc (dwfl->lookup_addr, sizeof naddr[0] * n);
+      if (unlikely (naddr == NULL))
+	return true;
+      int *nsegndx = realloc (dwfl->lookup_segndx, sizeof nsegndx[0] * n);
+      if (unlikely (nsegndx == NULL))
+	{
+	  free (naddr);
+	  return true;
+	}
+      dwfl->lookup_alloc = n;
+      dwfl->lookup_addr = naddr;
+      dwfl->lookup_segndx = nsegndx;
+    }
+
+  if (unlikely (i < dwfl->lookup_elts))
+    {
+      memcpy (&dwfl->lookup_addr[i + need], &dwfl->lookup_addr[i],
+	      need * sizeof dwfl->lookup_addr[0]);
+      memcpy (&dwfl->lookup_segndx[i + need], &dwfl->lookup_segndx[i],
+	      need * sizeof dwfl->lookup_segndx[0]);
+      if (dwfl->lookup_module != NULL)
+	memcpy (&dwfl->lookup_module[i + need], &dwfl->lookup_module[i],
+		need * sizeof dwfl->lookup_module[0]);
+    }
+
+  if (need_start)
+    {
+      dwfl->lookup_addr[i] = start;
+      dwfl->lookup_segndx[i] = segndx;
+      ++i;
+    }
+  else
+    dwfl->lookup_segndx[i - 1] = segndx;
+
+  if (need_end)
+    {
+      dwfl->lookup_addr[i] = end;
+      dwfl->lookup_segndx[i] = -1;
+    }
+
+  dwfl->lookup_elts += need;
+
+  return false;
+}
+
+static int
+lookup (Dwfl *dwfl, GElf_Addr address, int hint)
+{
+  if (hint >= 0
+      && address >= dwfl->lookup_addr[hint]
+      && ((size_t) hint + 1 == dwfl->lookup_elts
+	  || address <= dwfl->lookup_addr[hint + 1]))
+    return hint;
+
+  /* Do binary search on the array indexed by module load address.  */
+  size_t l = 0, u = dwfl->lookup_elts;
+  while (l < u)
+    {
+      size_t idx = (l + u) / 2;
+      if (address < dwfl->lookup_addr[idx])
+	u = idx;
+      else
+	{
+	  l = idx + 1;
+	  if (l == dwfl->lookup_elts || address < dwfl->lookup_addr[l])
+	    return idx;
+	}
+    }
+
+  return -1;
+}
+
+static bool
+reify_segments (Dwfl *dwfl)
+{
+  int hint = -1;
+  for (Dwfl_Module *mod = dwfl->modulelist; mod != NULL; mod = mod->next)
+    if (! mod->gc)
+      {
+	const GElf_Addr start = segment_start (dwfl, mod->low_addr);
+	const GElf_Addr end = segment_end (dwfl, mod->high_addr);
+
+	int idx = lookup (dwfl, start, hint);
+	if (unlikely (idx < 0))
+	  {
+	    /* Module starts below any segment.  Insert a low one.  */
+	    if (unlikely (insert (dwfl, 0, start, end, -1)))
+	      return true;
+	    idx = 0;
+	  }
+	else if (dwfl->lookup_addr[idx] > start)
+	  {
+	    /* The module starts in the middle of this segment.  Split it.  */
+	    if (unlikely (insert (dwfl, idx + 1, start, end,
+				  dwfl->lookup_segndx[idx])))
+	      return true;
+	    ++idx;
+	  }
+
+	if ((size_t) idx + 1 < dwfl->lookup_elts
+	    && end < dwfl->lookup_addr[idx + 1]
+	    /* The module ends in the middle of this segment.  Split it.  */
+	    && unlikely (insert (dwfl, idx + 1,
+				 end, dwfl->lookup_addr[idx + 1], -1)))
+	  return true;
+
+	if (dwfl->lookup_module == NULL)
+	  {
+	    dwfl->lookup_module = calloc (dwfl->lookup_alloc,
+					  sizeof dwfl->lookup_module[0]);
+	    if (unlikely (dwfl->lookup_module == NULL))
+	      return true;
+	  }
+
+	/* Cache a backpointer in the module.  */
+	mod->segment = idx;
+
+	/* Put MOD in the table for each segment that's inside it.  */
+	do
+	  dwfl->lookup_module[idx++] = mod;
+	while ((size_t) idx < dwfl->lookup_elts
+	       && dwfl->lookup_addr[idx] < end);
+	hint = (size_t) idx < dwfl->lookup_elts ? idx : -1;
+      }
+
+  return false;
+}
+
+int
+dwfl_addrsegment (Dwfl *dwfl, Dwarf_Addr address, Dwfl_Module **mod)
+{
+  if (unlikely (dwfl == NULL))
+    return -1;
+
+  if (unlikely (dwfl->lookup_module == NULL)
+      && mod != NULL
+      && unlikely (reify_segments (dwfl)))
+    {
+      __libdwfl_seterrno (DWFL_E_NOMEM);
+      return -1;
+    }
+
+  int idx = lookup (dwfl, address, -1);
+  if (likely (mod != NULL))
+    {
+      if (unlikely (idx < 0) || unlikely (dwfl->lookup_module == NULL))
+	*mod = NULL;
+      else
+	{
+	  *mod = dwfl->lookup_module[idx];
+
+	  /* If this segment does not have a module, but the address is
+	     the upper boundary of the previous segment's module, use that.  */
+	  if (*mod == NULL && idx > 0 && dwfl->lookup_addr[idx] == address)
+	    {
+	      *mod = dwfl->lookup_module[idx - 1];
+	      if (*mod != NULL && (*mod)->high_addr != address)
+		*mod = NULL;
+	    }
+	}
+    }
+
+  if (likely (idx >= 0))
+    /* Translate internal segment table index to user segment index.  */
+    idx = dwfl->lookup_segndx[idx];
+
+  return idx;
+}
+INTDEF (dwfl_addrsegment)
+
+int
+dwfl_report_segment (Dwfl *dwfl, int ndx, const GElf_Phdr *phdr, GElf_Addr bias,
+		     const void *ident)
+{
+  if (dwfl == NULL)
+    return -1;
+
+  if (ndx < 0)
+    ndx = dwfl->lookup_tail_ndx;
+
+  if (phdr->p_align > 1 && (dwfl->segment_align <= 1 ||
+			    phdr->p_align < dwfl->segment_align))
+    dwfl->segment_align = phdr->p_align;
+
+  GElf_Addr start = segment_start (dwfl, bias + phdr->p_vaddr);
+  GElf_Addr end = segment_end (dwfl, bias + phdr->p_vaddr + phdr->p_memsz);
+
+  /* Coalesce into the last one if contiguous and matching.  */
+  if (ndx != dwfl->lookup_tail_ndx
+      || ident == NULL
+      || ident != dwfl->lookup_tail_ident
+      || start != dwfl->lookup_tail_vaddr
+      || phdr->p_offset != dwfl->lookup_tail_offset)
+    {
+      /* Normally just appending keeps us sorted.  */
+
+      size_t i = dwfl->lookup_elts;
+      while (i > 0 && unlikely (start < dwfl->lookup_addr[i - 1]))
+	--i;
+
+      if (unlikely (insert (dwfl, i, start, end, ndx)))
+	{
+	  __libdwfl_seterrno (DWFL_E_NOMEM);
+	  return -1;
+	}
+    }
+
+  dwfl->lookup_tail_ident = ident;
+  dwfl->lookup_tail_vaddr = end;
+  dwfl->lookup_tail_offset = end - bias - phdr->p_vaddr + phdr->p_offset;
+  dwfl->lookup_tail_ndx = ndx + 1;
+
+  if (unlikely (dwfl->lookup_module != NULL))
+    {
+      free (dwfl->lookup_module);
+      dwfl->lookup_module = NULL;
+    }
+
+  return ndx;
+}
+INTDEF (dwfl_report_segment)