diff --git a/libdwfl/segment.c b/libdwfl/segment.c
new file mode 100644
index 0000000..d9599a7
--- /dev/null
+++ b/libdwfl/segment.c
@@ -0,0 +1,337 @@
+/* Manage address space lookup table for libdwfl.
+   Copyright (C) 2008, 2009, 2010, 2013, 2015 Red Hat, Inc.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   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 copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "libdwflP.h"
+
+GElf_Addr
+internal_function
+__libdwfl_segment_start (Dwfl *dwfl, GElf_Addr start)
+{
+  if (dwfl->segment_align > 1)
+    start &= -dwfl->segment_align;
+  return start;
+}
+
+GElf_Addr
+internal_function
+__libdwfl_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 + 1 >= 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))
+	{
+	  if (naddr != dwfl->lookup_addr)
+	    free (naddr);
+	  return true;
+	}
+      dwfl->lookup_alloc = n;
+      dwfl->lookup_addr = naddr;
+      dwfl->lookup_segndx = nsegndx;
+
+      if (dwfl->lookup_module != NULL)
+	{
+	  /* Make sure this array is big enough too.  */
+	  Dwfl_Module **old = dwfl->lookup_module;
+	  dwfl->lookup_module = realloc (dwfl->lookup_module,
+					 sizeof dwfl->lookup_module[0] * n);
+	  if (unlikely (dwfl->lookup_module == NULL))
+	    {
+	      free (old);
+	      return true;
+	    }
+	}
+    }
+
+  if (unlikely (i < dwfl->lookup_elts))
+    {
+      const size_t move = dwfl->lookup_elts - i;
+      memmove (&dwfl->lookup_addr[i + need], &dwfl->lookup_addr[i],
+	       move * sizeof dwfl->lookup_addr[0]);
+      memmove (&dwfl->lookup_segndx[i + need], &dwfl->lookup_segndx[i],
+	       move * sizeof dwfl->lookup_segndx[0]);
+      if (dwfl->lookup_module != NULL)
+	memmove (&dwfl->lookup_module[i + need], &dwfl->lookup_module[i],
+		 move * sizeof dwfl->lookup_module[0]);
+    }
+
+  if (need_start)
+    {
+      dwfl->lookup_addr[i] = start;
+      dwfl->lookup_segndx[i] = segndx;
+      if (dwfl->lookup_module != NULL)
+	dwfl->lookup_module[i] = NULL;
+      ++i;
+    }
+  else
+    dwfl->lookup_segndx[i - 1] = segndx;
+
+  if (need_end)
+    {
+      dwfl->lookup_addr[i] = end;
+      dwfl->lookup_segndx[i] = -1;
+      if (dwfl->lookup_module != NULL)
+	dwfl->lookup_module[i] = NULL;
+    }
+
+  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;
+  int highest = -1;
+  bool fixup = false;
+  for (Dwfl_Module *mod = dwfl->modulelist; mod != NULL; mod = mod->next)
+    if (! mod->gc)
+      {
+	const GElf_Addr start = __libdwfl_segment_start (dwfl, mod->low_addr);
+	const GElf_Addr end = __libdwfl_segment_end (dwfl, mod->high_addr);
+	bool resized = false;
+
+	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;
+	    resized = true;
+	  }
+	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;
+	    resized = true;
+	  }
+	else if (dwfl->lookup_addr[idx] < start)
+	  {
+	    /* The module starts past the end of this segment.
+	       Add a new one.  */
+	    if (unlikely (insert (dwfl, idx + 1, start, end, -1)))
+	      return true;
+	    ++idx;
+	    resized = true;
+	  }
+
+	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.  */
+	    if (unlikely (insert (dwfl, idx + 1,
+				  end, dwfl->lookup_addr[idx + 1], -1)))
+	      return true;
+	    resized = 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);
+	assert (dwfl->lookup_module[mod->segment] == mod);
+
+	if (resized && idx - 1 >= highest)
+	  /* Expanding the lookup tables invalidated backpointers
+	     we've already stored.  Reset those ones.  */
+	  fixup = true;
+
+	highest = idx - 1;
+	hint = (size_t) idx < dwfl->lookup_elts ? idx : -1;
+      }
+
+  if (fixup)
+    /* Reset backpointer indices invalidated by table insertions.  */
+    for (size_t idx = 0; idx < dwfl->lookup_elts; ++idx)
+      if (dwfl->lookup_module[idx] != NULL)
+	dwfl->lookup_module[idx]->segment = idx;
+
+  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;
+
+  if (unlikely (dwfl->lookup_module != NULL))
+    {
+      free (dwfl->lookup_module);
+      dwfl->lookup_module = NULL;
+    }
+
+  GElf_Addr start = __libdwfl_segment_start (dwfl, bias + phdr->p_vaddr);
+  GElf_Addr end = __libdwfl_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;
+
+  return ndx;
+}
+INTDEF (dwfl_report_segment)