Generate a complete exception frame header. Discard duplicate

exception frame information.

1 files changed, 1033 insertions, 14 deletions

diff --git a/gold/ehframe.cc b/gold/ehframe.cc
index 607654b..1c7b714 100644
--- a/gold/ehframe.cc
+++ b/gold/ehframe.cc
@@ -22,8 +22,13 @@
 
 #include "gold.h"
 
+#include <cstring>
+#include <algorithm>
+
 #include "elfcpp.h"
 #include "dwarf.h"
+#include "symtab.h"
+#include "reloc.h"
 #include "ehframe.h"
 
 namespace gold
@@ -31,7 +36,8 @@ namespace gold
 
 // This file handles generation of the exception frame header that
 // gcc's runtime support libraries use to find unwind information at
-// runtime.
+// runtime.  This file also handles discarding duplicate exception
+// frame information.
 
 // The exception frame header starts with four bytes:
 
@@ -68,16 +74,17 @@ namespace gold
 // the start of the exception frame header information.  The entries
 // are in sorted order by starting PC.
 
-// FIXME: We currently always generate an empty exception frame
-// header.
-
 const int eh_frame_hdr_size = 4;
 
 // Construct the exception frame header.
 
-Eh_frame_hdr::Eh_frame_hdr(Output_section* eh_frame_section)
+Eh_frame_hdr::Eh_frame_hdr(Output_section* eh_frame_section,
+			   const Eh_frame* eh_frame_data)
   : Output_section_data(4),
-    eh_frame_section_(eh_frame_section)
+    eh_frame_section_(eh_frame_section),
+    eh_frame_data_(eh_frame_data),
+    fde_offsets_(),
+    any_unrecognized_eh_frame_sections_(false)
 {
 }
 
@@ -86,7 +93,15 @@ Eh_frame_hdr::Eh_frame_hdr(Output_section* eh_frame_section)
 void
 Eh_frame_hdr::do_set_address(uint64_t, off_t)
 {
-  this->set_data_size(eh_frame_hdr_size + 4);
+  unsigned int data_size = eh_frame_hdr_size + 4;
+  if (!this->any_unrecognized_eh_frame_sections_)
+    {
+      unsigned int fde_count = this->eh_frame_data_->fde_count();
+      if (fde_count != 0)
+	data_size += 4 + 8 * fde_count;
+      this->fde_offsets_.reserve(fde_count);
+    }
+  this->set_data_size(data_size);
 }
 
 // Write the data to the flie.
@@ -94,6 +109,54 @@ Eh_frame_hdr::do_set_address(uint64_t, off_t)
 void
 Eh_frame_hdr::do_write(Output_file* of)
 {
+  if (parameters->get_size() == 32)
+    {
+      if (!parameters->is_big_endian())
+	{
+#ifdef HAVE_TARGET_32_LITTLE
+	  this->do_sized_write<32, false>(of);
+#else
+	  gold_unreachable();
+#endif
+	}
+      else
+	{
+#ifdef HAVE_TARGET_32_BIG
+	  this->do_sized_write<32, true>(of);
+#else
+	  gold_unreachable();
+#endif
+	}
+    }
+  else if (parameters->get_size() == 64)
+    {
+      if (!parameters->is_big_endian())
+	{
+#ifdef HAVE_TARGET_64_LITTLE
+	  this->do_sized_write<64, false>(of);
+#else
+	  gold_unreachable();
+#endif
+	}
+      else
+	{
+#ifdef HAVE_TARGET_64_BIG
+	  this->do_sized_write<64, true>(of);
+#else
+	  gold_unreachable();
+#endif
+	}
+    }
+  else
+    gold_unreachable();
+}
+
+// Write the data to the file with the right endianness.
+
+template<int size, bool big_endian>
+void
+Eh_frame_hdr::do_sized_write(Output_file* of)
+{
   const off_t off = this->offset();
   const off_t oview_size = this->data_size();
   unsigned char* const oview = of->get_output_view(off, oview_size);
@@ -108,18 +171,974 @@ Eh_frame_hdr::do_write(Output_file* of)
   uint64_t eh_frame_hdr_address = this->address();
   uint64_t eh_frame_offset = (eh_frame_address -
 			      (eh_frame_hdr_address + 4));
-  if (parameters->is_big_endian())
-    elfcpp::Swap<32, true>::writeval(oview + 4, eh_frame_offset);
+  elfcpp::Swap<32, big_endian>::writeval(oview + 4, eh_frame_offset);
+
+  if (this->any_unrecognized_eh_frame_sections_
+      || this->fde_offsets_.empty())
+    {
+      // There are no FDEs, or we didn't recognize the format of the
+      // some of the .eh_frame sections, so we can't write out the
+      // sorted table.
+      oview[2] = elfcpp::DW_EH_PE_omit;
+      oview[3] = elfcpp::DW_EH_PE_omit;
+
+      gold_assert(oview_size == 8);
+    }
   else
-    elfcpp::Swap<32, false>::writeval(oview + 4, eh_frame_offset);
+    {
+      oview[2] = elfcpp::DW_EH_PE_udata4;
+      oview[3] = elfcpp::DW_EH_PE_datarel | elfcpp::DW_EH_PE_sdata4;
+
+      elfcpp::Swap<32, big_endian>::writeval(oview + 8,
+					     this->fde_offsets_.size());
+
+      // We have the offsets of the FDEs in the .eh_frame section.  We
+      // couldn't easily get the PC values before, as they depend on
+      // relocations which are, of course, target specific.  This code
+      // is run after all those relocations have been applied to the
+      // output file.  Here we read the output file again to find the
+      // PC values.  Then we sort the list and write it out.
 
-  // We don't currently write out the sorted table.
-  oview[2] = elfcpp::DW_EH_PE_omit;
-  oview[3] = elfcpp::DW_EH_PE_omit;
+      Fde_addresses<size> fde_addresses(this->fde_offsets_.size());
+      this->get_fde_addresses<size, big_endian>(of, &this->fde_offsets_,
+						&fde_addresses);
 
-  gold_assert(oview_size == 8);
+      std::sort(fde_addresses.begin(), fde_addresses.end(),
+		Fde_address_compare<size>());
+
+      typename elfcpp::Elf_types<size>::Elf_Addr output_address;
+      output_address = this->address();
+
+      unsigned char* pfde = oview + 12;
+      for (typename Fde_addresses<size>::iterator p = fde_addresses.begin();
+	   p != fde_addresses.end();
+	   ++p)
+	{
+	  elfcpp::Swap<32, big_endian>::writeval(pfde,
+						 p->first - output_address);
+	  elfcpp::Swap<32, big_endian>::writeval(pfde + 4,
+						 p->second - output_address);
+	  pfde += 8;
+	}
+
+      gold_assert(pfde - oview == oview_size);
+    }
 
   of->write_output_view(off, oview_size, oview);
 }
 
+// Given the offset FDE_OFFSET of an FDE in the .eh_frame section, and
+// the contents of the .eh_frame section EH_FRAME_CONTENTS, where the
+// FDE's encoding is FDE_ENCODING, return the output address of the
+// FDE's PC.
+
+template<int size, bool big_endian>
+typename elfcpp::Elf_types<size>::Elf_Addr
+Eh_frame_hdr::get_fde_pc(const unsigned char* eh_frame_contents,
+			 off_t fde_offset, unsigned char fde_encoding)
+{
+  // The FDE starts with a 4 byte length and a 4 byte offset to the
+  // CIE.  The PC follows.
+  const unsigned char* p = eh_frame_contents + fde_offset + 8;
+
+  typename elfcpp::Elf_types<size>::Elf_Addr pc;
+  bool is_signed = (fde_encoding & elfcpp::DW_EH_PE_signed) != 0;
+  int pc_size = fde_encoding & 7;
+  if (pc_size == elfcpp::DW_EH_PE_absptr)
+    {
+      if (size == 32)
+	pc_size = elfcpp::DW_EH_PE_udata4;
+      else if (size == 64)
+	pc_size = elfcpp::DW_EH_PE_udata8;
+      else
+	gold_unreachable();
+    }
+
+  switch (pc_size)
+    {
+    case elfcpp::DW_EH_PE_udata2:
+      pc = elfcpp::Swap<16, big_endian>::readval(p);
+      if (is_signed)
+	pc = (pc ^ 0x8000) - 0x8000;
+      break;
+
+    case elfcpp::DW_EH_PE_udata4:
+      pc = elfcpp::Swap<32, big_endian>::readval(p);
+      if (size > 32 && is_signed)
+	pc = (pc ^ 0x80000000) - 0x80000000;
+      break;
+
+    case elfcpp::DW_EH_PE_udata8:
+      gold_assert(size == 64);
+      pc = elfcpp::Swap_unaligned<64, big_endian>::readval(p);
+      break;
+
+    default:
+      gold_unreachable();
+    }
+
+  return pc;
+}
+
+// Given an array of FDE offsets in the .eh_frame section, return an
+// array of offsets from the exception frame header to the FDE's
+// output PC and to the output address of the FDE itself.  We get the
+// FDE's PC by actually looking in the .eh_frame section we just wrote
+// to the output file.
+
+template<int size, bool big_endian>
+void
+Eh_frame_hdr::get_fde_addresses(Output_file* of,
+				const Fde_offsets* fde_offsets,
+				Fde_addresses<size>* fde_addresses)
+{
+  typename elfcpp::Elf_types<size>::Elf_Addr eh_frame_address;
+  eh_frame_address = this->eh_frame_section_->address();
+  off_t eh_frame_offset = this->eh_frame_section_->offset();
+  off_t eh_frame_size = this->eh_frame_section_->data_size();
+  const unsigned char* eh_frame_contents = of->get_input_view(eh_frame_offset,
+							      eh_frame_size);
+
+  for (Fde_offsets::const_iterator p = fde_offsets->begin();
+       p != fde_offsets->end();
+       ++p)
+    {
+      typename elfcpp::Elf_types<size>::Elf_Addr fde_pc;
+      fde_pc = this->get_fde_pc<size, big_endian>(eh_frame_contents,
+						  p->first, p->second);
+      fde_addresses->push_back(fde_pc, eh_frame_address + p->first);
+    }
+
+  of->free_input_view(eh_frame_offset, eh_frame_size, eh_frame_contents);
+}
+
+// Class Fde.
+
+// Write the FDE to OVIEW starting at OFFSET.  CIE_OFFSET is the
+// offset of the CIE in OVIEW.  FDE_ENCODING is the encoding, from the
+// CIE.  Record the FDE pc for EH_FRAME_HDR.  Return the new offset.
+
+template<int size, bool big_endian>
+off_t
+Fde::write(unsigned char* oview, off_t offset, off_t cie_offset,
+	   unsigned char fde_encoding, Eh_frame_hdr* eh_frame_hdr)
+{
+  size_t length = this->contents_.length();
+
+  // Write the length of the FDE as a 32-bit word.  The length word
+  // does not include the four bytes of the length word itself, but it
+  // does include the offset to the CIE.
+  elfcpp::Swap<32, big_endian>::writeval(oview + offset,
+					 length + 4);
+
+  // Write the offset to the CIE as a 32-bit word.  This is the
+  // difference between the address of the offset word itself and the
+  // CIE address.
+  elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4,
+					 offset + 4 - cie_offset);
+
+  // Copy the rest of the FDE.  Note that this is run before
+  // relocation processing is done on this section, so the relocations
+  // will later be applied to the FDE data.
+  memcpy(oview + offset + 8, this->contents_.data(), length);
+
+  // Tell the exception frame header about this FDE.
+  if (eh_frame_hdr != NULL)
+    eh_frame_hdr->record_fde(offset, fde_encoding);
+
+  return offset + length + 8;
+}
+
+// Class Cie.
+
+// Destructor.
+
+Cie::~Cie()
+{
+  for (std::vector<Fde*>::iterator p = this->fdes_.begin();
+       p != this->fdes_.end();
+       ++p)
+    delete *p;
+}
+
+// Set the output offset of a CIE.  Return the new output offset.
+
+off_t
+Cie::set_output_offset(off_t output_offset, unsigned int addralign,
+		       Merge_map* merge_map)
+{
+  size_t length = this->contents_.length();
+  gold_assert((length & (addralign - 1)) == 0);
+  // Add 4 for length and 4 for zero CIE identifier tag.
+  length += 8;
+
+  merge_map->add_mapping(this->object_, this->shndx_, this->input_offset_,
+			 length, output_offset);
+
+  for (std::vector<Fde*>::const_iterator p = this->fdes_.begin();
+       p != this->fdes_.end();
+       ++p)
+    {
+      (*p)->add_mapping(output_offset + length, merge_map);
+
+      size_t fde_length = (*p)->length();
+      gold_assert((fde_length & (addralign - 1)) == 0);
+      length += fde_length;
+    }
+
+  return output_offset + length;
+}
+
+// Write the CIE to OVIEW starting at OFFSET.  EH_FRAME_HDR is for FDE
+// recording.  Return the new offset.
+
+template<int size, bool big_endian>
+off_t
+Cie::write(unsigned char* oview, off_t offset, Eh_frame_hdr* eh_frame_hdr)
+{
+  off_t cie_offset = offset;
+
+  size_t length = this->contents_.length();
+
+  // Write the length of the CIE as a 32-bit word.  The length word
+  // does not include the four bytes of the length word itself.
+  elfcpp::Swap<32, big_endian>::writeval(oview + offset, length + 4);
+
+  // Write the tag which marks this as a CIE: a 32-bit zero.
+  elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4, 0);
+
+  // Write out the CIE data.
+  memcpy(oview + offset + 8, this->contents_.data(), length);
+  offset += length + 8;
+
+  // Write out the associated FDEs.
+  unsigned char fde_encoding = this->fde_encoding_;
+  for (std::vector<Fde*>::const_iterator p = this->fdes_.begin();
+       p != this->fdes_.end();
+       ++p)
+    offset = (*p)->write<size, big_endian>(oview, offset, cie_offset,
+					   fde_encoding, eh_frame_hdr);
+
+  return offset;
+}
+
+// We track all the CIEs we see, and merge them when possible.  This
+// works because each FDE holds an offset to the relevant CIE: we
+// rewrite the FDEs to point to the merged CIE.  This is worthwhile
+// because in a typical C++ program many FDEs in many different object
+// files will use the same CIE.
+
+// An equality operator for Cie.
+
+bool
+operator==(const Cie& cie1, const Cie& cie2)
+{
+  return (cie1.personality_name_ == cie2.personality_name_
+	  && cie1.contents_ == cie2.contents_);
+}
+
+// A less-than operator for Cie.
+
+bool
+operator<(const Cie& cie1, const Cie& cie2)
+{
+  if (cie1.personality_name_ != cie2.personality_name_)
+    return cie1.personality_name_ < cie2.personality_name_;
+  return cie1.contents_ < cie2.contents_;
+}
+
+// Class Eh_frame.
+
+Eh_frame::Eh_frame()
+  : Output_section_data(Output_data::default_alignment()),
+    eh_frame_hdr_(NULL),
+    cie_offsets_(),
+    unmergeable_cie_offsets_(),
+    merge_map_()
+{
+}
+
+// Skip an LEB128, updating *PP to point to the next character.
+// Return false if we ran off the end of the string.
+
+bool
+Eh_frame::skip_leb128(const unsigned char** pp, const unsigned char* pend)
+{
+  const unsigned char* p;
+  for (p = *pp; p < pend; ++p)
+    {
+      if ((*p & 0x80) == 0)
+	{
+	  *pp = p + 1;
+	  return true;
+	}
+    }
+  return false;
+}
+
+// Add input section SHNDX in OBJECT to an exception frame section.
+// SYMBOLS is the contents of the symbol table section (size
+// SYMBOLS_SIZE), SYMBOL_NAMES is the symbol names section (size
+// SYMBOL_NAMES_SIZE).  RELOC_SHNDX is the index of a relocation
+// section applying to SHNDX, or 0 if none, or -1U if more than one.
+// RELOC_TYPE is the type of the reloc section if there is one, either
+// SHT_REL or SHT_RELA.  We try to parse the input exception frame
+// data into our data structures.  If we can't do it, we return false
+// to mean that the section should be handled as a normal input
+// section.
+
+template<int size, bool big_endian>
+bool
+Eh_frame::add_ehframe_input_section(
+    Sized_relobj<size, big_endian>* object,
+    const unsigned char* symbols,
+    off_t symbols_size,
+    const unsigned char* symbol_names,
+    off_t symbol_names_size,
+    unsigned int shndx,
+    unsigned int reloc_shndx,
+    unsigned int reloc_type)
+{
+  // Get the section contents.
+  off_t contents_len;
+  const unsigned char* pcontents = object->section_contents(shndx,
+							    &contents_len,
+							    false);
+  if (contents_len == 0)
+    return false;
+
+  // If this is the marker section for the end of the data, then
+  // return false to force it to be handled as an ordinary input
+  // section.  If we don't do this, we won't correctly handle the case
+  // of unrecognized .eh_frame sections.
+  if (contents_len == 4
+      && elfcpp::Swap<32, big_endian>::readval(pcontents) == 0)
+    return false;
+
+  New_cies new_cies;
+  if (!this->do_add_ehframe_input_section(object, symbols, symbols_size,
+					  symbol_names, symbol_names_size,
+					  shndx, reloc_shndx,
+					  reloc_type, pcontents,
+					  contents_len, &new_cies))
+    {
+      this->eh_frame_hdr_->found_unrecognized_eh_frame_section();
+
+      for (New_cies::iterator p = new_cies.begin();
+	   p != new_cies.end();
+	   ++p)
+	delete p->first;
+
+      return false;
+    }
+
+  // Now that we know we are using this section, record any new CIEs
+  // that we found.
+  for (New_cies::const_iterator p = new_cies.begin();
+       p != new_cies.end();
+       ++p)
+    {
+      uint64_t zero = 0;
+      if (p->second)
+	this->cie_offsets_.insert(std::make_pair(p->first, zero));
+      else
+	this->unmergeable_cie_offsets_.push_back(std::make_pair(p->first,
+								zero));
+    }
+
+  return true;
+}
+
+// The bulk of the implementation of add_ehframe_input_section.
+
+template<int size, bool big_endian>
+bool
+Eh_frame::do_add_ehframe_input_section(
+    Sized_relobj<size, big_endian>* object,
+    const unsigned char* symbols,
+    off_t symbols_size,
+    const unsigned char* symbol_names,
+    off_t symbol_names_size,
+    unsigned int shndx,
+    unsigned int reloc_shndx,
+    unsigned int reloc_type,
+    const unsigned char* pcontents,
+    off_t contents_len,
+    New_cies* new_cies)
+{
+  typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
+  Track_relocs<size, big_endian> relocs;
+
+  const unsigned char* p = pcontents;
+  const unsigned char* pend = p + contents_len;
+
+  // Get the contents of the reloc section if any.
+  if (!relocs.initialize(object, reloc_shndx, reloc_type))
+    return false;
+
+  // Keep track of which CIEs are at which offsets.
+  Offsets_to_cie cies;
+
+  while (p < pend)
+    {
+      if (pend - p < 4)
+	return false;
+
+      // There shouldn't be any relocations here.
+      if (relocs.advance(p + 4 - pcontents) > 0)
+	return false;
+
+      unsigned int len = elfcpp::Swap<32, big_endian>::readval(p);
+      p += 4;
+      if (len == 0)
+	{
+	  // We should only find a zero-length entry at the end of the
+	  // section.
+	  if (p < pend)
+	    return false;
+	  break;
+	}
+      // We don't support a 64-bit .eh_frame.
+      if (len == 0xffffffff)
+	return false;
+      if (static_cast<unsigned int>(pend - p) < len)
+	return false;
+
+      const unsigned char* const pentend = p + len;
+
+      if (pend - p < 4)
+	return false;
+      if (relocs.advance(p + 4 - pcontents) > 0)
+	return false;
+
+      unsigned int id = elfcpp::Swap<32, big_endian>::readval(p);
+      p += 4;
+
+      if (id == 0)
+	{
+	  // CIE.
+	  if (!this->read_cie(object, shndx, symbols, symbols_size,
+			      symbol_names, symbol_names_size,
+			      pcontents, p, pentend, &relocs, &cies,
+			      new_cies))
+	    return false;
+	}
+      else
+	{
+	  // FDE.
+	  if (!this->read_fde(object, shndx, symbols, symbols_size,
+			      pcontents, id, p, pentend, &relocs, &cies))
+	    return false;
+	}
+
+      p = pentend;
+    }
+
+  return true;
+}
+
+// Read a CIE.  Return false if we can't parse the information.
+
+template<int size, bool big_endian>
+bool
+Eh_frame::read_cie(Sized_relobj<size, big_endian>* object,
+		   unsigned int shndx,
+		   const unsigned char* symbols,
+		   off_t symbols_size,
+		   const unsigned char* symbol_names,
+		   off_t symbol_names_size,
+		   const unsigned char* pcontents,
+		   const unsigned char* pcie,
+		   const unsigned char *pcieend,
+		   Track_relocs<size, big_endian>* relocs,
+		   Offsets_to_cie* cies,
+		   New_cies* new_cies)
+{
+  bool mergeable = true;
+
+  // We need to find the personality routine if there is one, since we
+  // can only merge CIEs which use the same routine.  We also need to
+  // find the FDE encoding if there is one, so that we can read the PC
+  // from the FDE.
+
+  const unsigned char* p = pcie;
+
+  if (pcieend - p < 1)
+    return false;
+  unsigned char version = *p++;
+  if (version != 1 && version != 3)
+    return false;
+
+  const unsigned char* paug = p;
+  const void* paugendv = memchr(p, '\0', pcieend - p);
+  const unsigned char* paugend = static_cast<const unsigned char*>(paugendv);
+  if (paugend == NULL)
+    return false;
+  p = paugend + 1;
+
+  if (paug[0] == 'e' && paug[1] == 'h')
+    {
+      // This is a CIE from gcc before version 3.0.  We can't merge
+      // these.  We can still read the FDEs.
+      mergeable = false;
+      paug += 2;
+      if (*paug != '\0')
+	return false;
+      if (pcieend - p < size / 8)
+	return false;
+      p += size / 8;
+    }
+
+  // Skip the code alignment.
+  if (!skip_leb128(&p, pcieend))
+    return false;
+
+  // Skip the data alignment.
+  if (!skip_leb128(&p, pcieend))
+    return false;
+
+  // Skip the return column.
+  if (version == 1)
+    {
+      if (pcieend - p < 1)
+	return false;
+      ++p;
+    }
+  else
+    {
+      if (!skip_leb128(&p, pcieend))
+	return false;
+    }
+
+  if (*paug == 'z')
+    {
+      ++paug;
+      // Skip the augmentation size.
+      if (!skip_leb128(&p, pcieend))
+	return false;
+    }
+
+  unsigned char fde_encoding = elfcpp::DW_EH_PE_absptr;
+  int per_offset = -1;
+  while (*paug != '\0')
+    {
+      switch (*paug)
+	{
+	case 'L': // LSDA encoding.
+	  if (pcieend - p < 1)
+	    return false;
+	  ++p;
+	  break;
+
+	case 'R': // FDE encoding.
+	  if (pcieend - p < 1)
+	    return false;
+	  fde_encoding = *p;
+	  switch (fde_encoding & 7)
+	    {
+	    case elfcpp::DW_EH_PE_absptr:
+	    case elfcpp::DW_EH_PE_udata2:
+	    case elfcpp::DW_EH_PE_udata4:
+	    case elfcpp::DW_EH_PE_udata8:
+	      break;
+	    default:
+	      return false;
+	    }
+	  ++p;
+	  break;
+
+	case 'S':
+	  break;
+
+	case 'P':
+	  // Personality encoding.
+	  {
+	    if (pcieend - p < 1)
+	      return false;
+	    unsigned char per_encoding = *p;
+	    ++p;
+
+	    if ((per_encoding & 0x60) == 0x60)
+	      return false;
+	    unsigned int per_width;
+	    switch (per_encoding & 7)
+	      {
+	      case elfcpp::DW_EH_PE_udata2:
+		per_width = 2;
+		break;
+	      case elfcpp::DW_EH_PE_udata4:
+		per_width = 4;
+		break;
+	      case elfcpp::DW_EH_PE_udata8:
+		per_width = 8;
+		break;
+	      case elfcpp::DW_EH_PE_absptr:
+		per_width = size / 8;
+		break;
+	      default:
+		return false;
+	      }
+
+	    if ((per_encoding & 0xf0) == elfcpp::DW_EH_PE_aligned)
+	      {
+		unsigned int len = p - pcie;
+		len += per_width - 1;
+		len &= ~ (per_width - 1);
+		if (static_cast<unsigned int>(pcieend - p) < len)
+		  return false;
+		p += len;
+	      }
+
+	    per_offset = p - pcontents;
+
+	    if (static_cast<unsigned int>(pcieend - p) < per_width)
+	      return false;
+	    p += per_width;
+	  }
+	  break;
+
+	default:
+	  return false;
+	}
+
+      ++paug;
+    }
+
+  const char* personality_name = "";
+  if (per_offset != -1)
+    {
+      if (relocs->advance(per_offset) > 0)
+	return false;
+      if (relocs->next_offset() != per_offset)
+	return false;
+
+      unsigned int personality_symndx = relocs->next_symndx();
+      if (personality_symndx == -1U)
+	return false;
+
+      if (personality_symndx < object->local_symbol_count())
+	{
+	  // We can only merge this CIE if the personality routine is
+	  // a global symbol.  We can still read the FDEs.
+	  mergeable = false;
+	}
+      else
+	{
+	  const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
+	  if (personality_symndx >= symbols_size / sym_size)
+	    return false;
+	  elfcpp::Sym<size, big_endian> sym(symbols
+					    + (personality_symndx * sym_size));
+	  unsigned int name_offset = sym.get_st_name();
+	  if (name_offset >= symbol_names_size)
+	    return false;
+	  personality_name = (reinterpret_cast<const char*>(symbol_names)
+			      + name_offset);
+	}
+
+      int r = relocs->advance(per_offset + 1);
+      gold_assert(r == 1);
+    }
+
+  if (relocs->advance(pcieend - pcontents) > 0)
+    return false;
+
+  Cie cie(object, shndx, (pcie - 8) - pcontents, fde_encoding, 
+	  personality_name, pcie, pcieend - pcie);
+  Cie* cie_pointer = NULL;
+  if (mergeable)
+    {
+      Cie_offsets::iterator find_cie = this->cie_offsets_.find(&cie);
+      if (find_cie != this->cie_offsets_.end())
+	cie_pointer = find_cie->first;
+      else
+	{
+	  // See if we already saw this CIE in this object file.
+	  for (New_cies::const_iterator pc = new_cies->begin();
+	       pc != new_cies->end();
+	       ++pc)
+	    {
+	      if (*(pc->first) == cie)
+		{
+		  cie_pointer = pc->first;
+		  break;
+		}
+	    }
+	}
+    }
+
+  if (cie_pointer == NULL)
+    {
+      cie_pointer = new Cie(cie);
+      new_cies->push_back(std::make_pair(cie_pointer, mergeable));
+    }
+  else
+    {
+      // We are deleting this CIE.  Record that in our mapping from
+      // input sections to the output section.  At this point we don't
+      // know for sure that we are doing a special mapping for this
+      // input section, but that's OK--if we don't do a special
+      // mapping, nobody will ever ask for the mapping we add here.
+      this->merge_map_.add_mapping(object, shndx, (pcie - 8) - pcontents,
+				   pcieend - (pcie - 8), -1);
+    }
+
+  // Record this CIE plus the offset in the input section.
+  cies->insert(std::make_pair(pcie - pcontents, cie_pointer));
+
+  return true;
+}
+
+// Read an FDE.  Return false if we can't parse the information.
+
+template<int size, bool big_endian>
+bool
+Eh_frame::read_fde(Sized_relobj<size, big_endian>* object,
+		   unsigned int shndx,
+		   const unsigned char* symbols,
+		   off_t symbols_size,
+		   const unsigned char* pcontents,
+		   unsigned int offset,
+		   const unsigned char* pfde,
+		   const unsigned char *pfdeend,
+		   Track_relocs<size, big_endian>* relocs,
+		   Offsets_to_cie* cies)
+{
+  // OFFSET is the distance between the 4 bytes before PFDE to the
+  // start of the CIE.  The offset we recorded for the CIE is 8 bytes
+  // after the start of the CIE--after the length and the zero tag.
+  unsigned int cie_offset = (pfde - 4 - pcontents) - offset + 8;
+  Offsets_to_cie::const_iterator pcie = cies->find(cie_offset);
+  if (pcie == cies->end())
+    return false;
+  Cie* cie = pcie->second;
+
+  // The FDE should start with a reloc to the start of the code which
+  // it describes.
+  if (relocs->advance(pfde - pcontents) > 0)
+    return false;
+
+  if (relocs->next_offset() != pfde - pcontents)
+    return false;
+
+  unsigned int symndx = relocs->next_symndx();
+  if (symndx == -1U)
+    return false;
+
+  // There can be another reloc in the FDE, if the CIE specifies an
+  // LSDA (language specific data area).  We currently don't care.  We
+  // will care later if we want to optimize the LSDA from an absolute
+  // pointer to a PC relative offset when generating a shared library.
+  relocs->advance(pfdeend - pcontents);
+
+  unsigned int fde_shndx;
+  const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
+  if (symndx >= symbols_size / sym_size)
+    return false;
+  elfcpp::Sym<size, big_endian> sym(symbols + symndx * sym_size);
+  fde_shndx = sym.get_st_shndx();
+
+  if (fde_shndx != elfcpp::SHN_UNDEF
+      && fde_shndx < object->shnum()
+      && !object->is_section_included(fde_shndx))
+    {
+      // This FDE applies to a section which we are discarding.  We
+      // can discard this FDE.
+      this->merge_map_.add_mapping(object, shndx, (pfde - 8) - pcontents,
+				   pfdeend - (pfde - 8), -1);
+      return true;
+    }
+
+  cie->add_fde(new Fde(object, shndx, (pfde - 8) - pcontents,
+		       pfde, pfdeend - pfde));
+
+  return true;
+}
+
+// Return the number of FDEs.
+
+unsigned int
+Eh_frame::fde_count() const
+{
+  unsigned int ret = 0;
+  for (Unmergeable_cie_offsets::const_iterator p =
+	 this->unmergeable_cie_offsets_.begin();
+       p != this->unmergeable_cie_offsets_.end();
+       ++p)
+    ret += p->first->fde_count();
+  for (Cie_offsets::const_iterator p = this->cie_offsets_.begin();
+       p != this->cie_offsets_.end();
+       ++p)
+    ret += p->first->fde_count();
+  return ret;
+}
+
+// Set the final data size.
+
+void
+Eh_frame::do_set_address(uint64_t, off_t start_file_offset)
+{
+  off_t output_offset = 0;
+
+  for (Unmergeable_cie_offsets::iterator p =
+	 this->unmergeable_cie_offsets_.begin();
+       p != this->unmergeable_cie_offsets_.end();
+       ++p)
+    {
+      p->second = start_file_offset + output_offset;
+      output_offset = p->first->set_output_offset(output_offset,
+						  this->addralign(),
+						  &this->merge_map_);
+    }
+
+  for (Cie_offsets::iterator p = this->cie_offsets_.begin();
+       p != this->cie_offsets_.end();
+       ++p)
+    {
+      p->second = start_file_offset + output_offset;
+      output_offset = p->first->set_output_offset(output_offset,
+						  this->addralign(),
+						  &this->merge_map_);
+    }
+
+  gold_assert((output_offset & (this->addralign() - 1)) == 0);
+  this->set_data_size(output_offset);
+}
+
+// Return an output offset for an input offset.
+
+bool
+Eh_frame::do_output_offset(const Relobj* object, unsigned int shndx,
+			   off_t offset, off_t* poutput) const
+{
+  return this->merge_map_.get_output_offset(object, shndx, offset, poutput);
+}
+
+// Write the data to the output file.
+
+void
+Eh_frame::do_write(Output_file* of)
+{
+  const off_t offset = this->offset();
+  const off_t oview_size = this->data_size();
+  unsigned char* const oview = of->get_output_view(offset, oview_size);
+
+  if (parameters->get_size() == 32)
+    {
+      if (!parameters->is_big_endian())
+	{
+#ifdef HAVE_TARGET_32_LITTLE
+	  this->do_sized_write<32, false>(oview);
+#else
+	  gold_unreachable();
+#endif
+	}
+      else
+	{
+#ifdef HAVE_TARGET_32_BIG
+	  this->do_sized_write<32, true>(oview);
+#else
+	  gold_unreachable();
+#endif
+	}
+    }
+  else if (parameters->get_size() == 64)
+    {
+      if (!parameters->is_big_endian())
+	{
+#ifdef HAVE_TARGET_64_LITTLE
+	  this->do_sized_write<64, false>(oview);
+#else
+	  gold_unreachable();
+#endif
+	}
+      else
+	{
+#ifdef HAVE_TARGET_64_BIG
+	  this->do_sized_write<64, true>(oview);
+#else
+	  gold_unreachable();
+#endif
+	}
+    }
+  else
+    gold_unreachable();
+
+  of->write_output_view(offset, oview_size, oview);
+}
+
+// Write the data to the output file--template version.
+
+template<int size, bool big_endian>
+void
+Eh_frame::do_sized_write(unsigned char* oview)
+{
+  off_t o = 0;
+  for (Unmergeable_cie_offsets::iterator p =
+	 this->unmergeable_cie_offsets_.begin();
+       p != this->unmergeable_cie_offsets_.end();
+       ++p)
+    o = p->first->write<size, big_endian>(oview, o, this->eh_frame_hdr_);
+  for (Cie_offsets::iterator p = this->cie_offsets_.begin();
+       p != this->cie_offsets_.end();
+       ++p)
+    o = p->first->write<size, big_endian>(oview, o, this->eh_frame_hdr_);
+}
+
+#ifdef HAVE_TARGET_32_LITTLE
+template
+bool
+Eh_frame::add_ehframe_input_section<32, false>(
+    Sized_relobj<32, false>* object,
+    const unsigned char* symbols,
+    off_t symbols_size,
+    const unsigned char* symbol_names,
+    off_t symbol_names_size,
+    unsigned int shndx,
+    unsigned int reloc_shndx,
+    unsigned int reloc_type);
+#endif
+
+#ifdef HAVE_TARGET_32_BIG
+template
+bool
+Eh_frame::add_ehframe_input_section<32, true>(
+    Sized_relobj<32, true>* object,
+    const unsigned char* symbols,
+    off_t symbols_size,
+    const unsigned char* symbol_names,
+    off_t symbol_names_size,
+    unsigned int shndx,
+    unsigned int reloc_shndx,
+    unsigned int reloc_type);
+#endif
+
+#ifdef HAVE_TARGET_64_LITTLE
+template
+bool
+Eh_frame::add_ehframe_input_section<64, false>(
+    Sized_relobj<64, false>* object,
+    const unsigned char* symbols,
+    off_t symbols_size,
+    const unsigned char* symbol_names,
+    off_t symbol_names_size,
+    unsigned int shndx,
+    unsigned int reloc_shndx,
+    unsigned int reloc_type);
+#endif
+
+#ifdef HAVE_TARGET_64_BIG
+template
+bool
+Eh_frame::add_ehframe_input_section<64, true>(
+    Sized_relobj<64, true>* object,
+    const unsigned char* symbols,
+    off_t symbols_size,
+    const unsigned char* symbol_names,
+    off_t symbol_names_size,
+    unsigned int shndx,
+    unsigned int reloc_shndx,
+    unsigned int reloc_type);
+#endif
+
 } // End namespace gold.