From Craig Silverstein: Add first version of generating error messages

with file name and line number.

1 files changed, 529 insertions, 0 deletions

diff --git a/gold/dwarf_reader.cc b/gold/dwarf_reader.cc
new file mode 100644
index 0000000..05809a7
--- /dev/null
+++ b/gold/dwarf_reader.cc
@@ -0,0 +1,529 @@
+// dwarf_reader.cc -- parse dwarf2/3 debug information
+
+// Copyright 2007 Free Software Foundation, Inc.
+// Written by Ian Lance Taylor <iant@google.com>.
+
+// This file is part of gold.
+
+// 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 "gold.h"
+
+#include "elfcpp_swap.h"
+#include "dwarf.h"
+#include "dwarf_reader.h"
+
+namespace {
+
+// Read an unsigned LEB128 number.  Each byte contains 7 bits of
+// information, plus one bit saying whether the number continues or
+// not.
+
+uint64_t
+read_unsigned_LEB_128(const unsigned char* buffer, size_t* len)
+{
+  uint64_t result = 0;
+  size_t num_read = 0;
+  unsigned int shift = 0;
+  unsigned char byte;
+
+  do
+    {
+      byte = *buffer++;
+      num_read++;
+      result |= (static_cast<uint64_t>(byte & 0x7f)) << shift;
+      shift += 7;
+    }
+  while (byte & 0x80);
+
+  *len = num_read;
+
+  return result;
+}
+
+// Read a signed LEB128 number.  These are like regular LEB128
+// numbers, except the last byte may have a sign bit set.
+
+int64_t
+read_signed_LEB_128(const unsigned char* buffer, size_t* len)
+{
+  int64_t result = 0;
+  int shift = 0;
+  size_t num_read = 0;
+  unsigned char byte;
+
+  do
+    {
+      byte = *buffer++;
+      num_read++;
+      result |= (static_cast<uint64_t>(byte & 0x7f) << shift);
+      shift += 7;
+    }
+  while (byte & 0x80);
+
+  if ((shift < 8 * static_cast<int>(sizeof(result))) && (byte & 0x40))
+    result |= -((static_cast<int64_t>(1)) << shift);
+  *len = num_read;
+  return result;
+}
+
+} // End anonymous namespace.
+
+
+namespace gold {
+
+// This is the format of a DWARF2/3 line state machine that we process
+// opcodes using.  There is no need for anything outside the lineinfo
+// processor to know how this works.
+
+struct LineStateMachine
+{
+  int file_num;
+  uint64_t address;
+  int line_num;
+  int column_num;
+  unsigned int shndx;    // the section address refers to
+  bool is_stmt;          // stmt means statement.
+  bool basic_block;
+  bool end_sequence;
+};
+
+static void
+ResetLineStateMachine(struct LineStateMachine* lsm, bool default_is_stmt)
+{
+  lsm->file_num = 1;
+  lsm->address = 0;
+  lsm->line_num = 1;
+  lsm->column_num = 0;
+  lsm->shndx = -1;
+  lsm->is_stmt = default_is_stmt;
+  lsm->basic_block = false;
+  lsm->end_sequence = false;
+}
+
+// Read the DWARF header.
+
+template<int size, bool big_endian>
+const unsigned char*
+Dwarf_line_info::read_header_prolog(const unsigned char* lineptr)
+{
+  uint32_t initial_length = elfcpp::Swap<32, big_endian>::readval(lineptr);
+  lineptr += 4;
+
+  // In DWARF2/3, if the initial length is all 1 bits, then the offset
+  // size is 8 and we need to read the next 8 bytes for the real length.
+  if (initial_length == 0xffffffff)
+    {
+      header_.offset_size = 8;
+      initial_length = elfcpp::Swap<64, big_endian>::readval(lineptr);
+      lineptr += 8;
+    }
+  else
+    header_.offset_size = 4;
+
+  header_.total_length = initial_length;
+
+  gold_assert(lineptr + header_.total_length <= buffer_end_);
+
+  header_.version = elfcpp::Swap<16, big_endian>::readval(lineptr);
+  lineptr += 2;
+
+  if (header_.offset_size == 4)
+    header_.prologue_length = elfcpp::Swap<32, big_endian>::readval(lineptr);
+  else
+    header_.prologue_length = elfcpp::Swap<64, big_endian>::readval(lineptr);
+  lineptr += header_.offset_size;
+
+  header_.min_insn_length = *lineptr;
+  lineptr += 1;
+
+  header_.default_is_stmt = *lineptr;
+  lineptr += 1;
+
+  header_.line_base = *reinterpret_cast<const signed char*>(lineptr);
+  lineptr += 1;
+
+  header_.line_range = *lineptr;
+  lineptr += 1;
+
+  header_.opcode_base = *lineptr;
+  lineptr += 1;
+
+  header_.std_opcode_lengths.reserve(header_.opcode_base + 1);
+  header_.std_opcode_lengths[0] = 0;
+  for (int i = 1; i < header_.opcode_base; i++)
+    {
+      header_.std_opcode_lengths[i] = *lineptr;
+      lineptr += 1;
+    }
+
+  return lineptr;
+}
+
+// The header for a debug_line section is mildly complicated, because
+// the line info is very tightly encoded.
+
+const unsigned char*
+Dwarf_line_info::read_header_tables(const unsigned char* lineptr)
+{
+  // It is legal for the directory entry table to be empty.
+  if (*lineptr)
+    {
+      int dirindex = 1;
+      while (*lineptr)
+        {
+          const unsigned char* dirname = lineptr;
+          gold_assert(dirindex == static_cast<int>(directories_.size()));
+          directories_.push_back(reinterpret_cast<const char*>(dirname));
+          lineptr += directories_.back().size() + 1;
+          dirindex++;
+        }
+    }
+  lineptr++;
+
+  // It is also legal for the file entry table to be empty.
+  if (*lineptr)
+    {
+      int fileindex = 1;
+      size_t len;
+      while (*lineptr)
+        {
+          const char* filename = reinterpret_cast<const char*>(lineptr);
+          lineptr += strlen(filename) + 1;
+
+          uint64_t dirindex = read_unsigned_LEB_128(lineptr, &len);
+          if (dirindex >= directories_.size())
+            dirindex = 0;
+          lineptr += len;
+
+          read_unsigned_LEB_128(lineptr, &len);   // mod_time
+          lineptr += len;
+
+          read_unsigned_LEB_128(lineptr, &len);   // filelength
+          lineptr += len;
+
+          gold_assert(fileindex == static_cast<int>(files_.size()));
+          files_.push_back(std::pair<int, std::string>(dirindex, filename));
+          fileindex++;
+        }
+    }
+  lineptr++;
+
+  return lineptr;
+}
+
+// Process a single opcode in the .debug.line structure.
+
+// Templating on size and big_endian would yield more efficient (and
+// simpler) code, but would bloat the binary.  Speed isn't important
+// here.
+
+bool
+Dwarf_line_info::process_one_opcode(int size, bool big_endian,
+                                    const unsigned char* start,
+                                    struct LineStateMachine* lsm,
+                                    size_t* len)
+{
+  size_t oplen = 0;
+  size_t templen;
+  unsigned char opcode = *start;
+  oplen++;
+  start++;
+
+  // If the opcode is great than the opcode_base, it is a special
+  // opcode. Most line programs consist mainly of special opcodes.
+  if (opcode >= header_.opcode_base)
+    {
+      opcode -= header_.opcode_base;
+      const int advance_address = ((opcode / header_.line_range)
+                                   * header_.min_insn_length);
+      lsm->address += advance_address;
+
+      const int advance_line = ((opcode % header_.line_range)
+                                + header_.line_base);
+      lsm->line_num += advance_line;
+      lsm->basic_block = true;
+      *len = oplen;
+      return true;
+    }
+
+  // Otherwise, we have the regular opcodes
+  switch (opcode)
+    {
+    case elfcpp::DW_LNS_copy:
+      lsm->basic_block = false;
+      *len = oplen;
+      return true;
+
+    case elfcpp::DW_LNS_advance_pc:
+      {
+        const uint64_t advance_address
+            = read_unsigned_LEB_128(start, &templen);
+        oplen += templen;
+        lsm->address += header_.min_insn_length * advance_address;
+      }
+      break;
+
+    case elfcpp::DW_LNS_advance_line:
+      {
+        const uint64_t advance_line = read_signed_LEB_128(start, &templen);
+        oplen += templen;
+        lsm->line_num += advance_line;
+      }
+      break;
+
+    case elfcpp::DW_LNS_set_file:
+      {
+        const uint64_t fileno = read_unsigned_LEB_128(start, &templen);
+        oplen += templen;
+        lsm->file_num = fileno;
+      }
+      break;
+
+    case elfcpp::DW_LNS_set_column:
+      {
+        const uint64_t colno = read_unsigned_LEB_128(start, &templen);
+        oplen += templen;
+        lsm->column_num = colno;
+      }
+      break;
+
+    case elfcpp::DW_LNS_negate_stmt:
+      lsm->is_stmt = !lsm->is_stmt;
+      break;
+
+    case elfcpp::DW_LNS_set_basic_block:
+      lsm->basic_block = true;
+      break;
+
+    case elfcpp::DW_LNS_fixed_advance_pc:
+      {
+        int advance_address;
+        if (big_endian)
+          advance_address = elfcpp::Swap<16, true>::readval(start);
+        else
+          advance_address = elfcpp::Swap<16, false>::readval(start);
+        oplen += 2;
+        lsm->address += advance_address;
+      }
+      break;
+
+    case elfcpp::DW_LNS_const_add_pc:
+      {
+        const int advance_address = (header_.min_insn_length
+                                     * ((255 - header_.opcode_base)
+                                        / header_.line_range));
+        lsm->address += advance_address;
+      }
+      break;
+
+    case elfcpp::DW_LNS_extended_op:
+      {
+        const uint64_t extended_op_len
+            = read_unsigned_LEB_128(start, &templen);
+        start += templen;
+        oplen += templen + extended_op_len;
+
+        const unsigned char extended_op = *start;
+        start++;
+
+        switch (extended_op)
+          {
+          case elfcpp::DW_LNE_end_sequence:
+            lsm->end_sequence = true;
+            *len = oplen;
+            return true;
+
+          case elfcpp::DW_LNE_set_address:
+            // FIXME: modify the address based on the reloc
+            if (size == 32 && big_endian == false)
+              lsm->address = elfcpp::Swap<32, false>::readval(start);
+            else if (size == 32 && big_endian == true)
+              lsm->address = elfcpp::Swap<32, true>::readval(start);
+            else if (size == 64 && big_endian == false)
+              lsm->address = elfcpp::Swap<64, false>::readval(start);
+            else if (size == 64 && big_endian == true)
+              lsm->address = elfcpp::Swap<64, true>::readval(start);
+            else
+              gold_assert(false);  // We need to implement more cases, then.
+            // FIXME: set lsm->shndx from the reloc
+            lsm->shndx = 1;
+            break;
+
+          case elfcpp::DW_LNE_define_file:
+            {
+              const char* filename  = reinterpret_cast<const char*>(start);
+              templen = strlen(filename) + 1;
+              start += templen;
+
+              uint64_t dirindex = read_unsigned_LEB_128(start, &templen);
+              if (dirindex >= directories_.size())
+                dirindex = 0;
+              oplen += templen;
+
+              read_unsigned_LEB_128(start, &templen);   // mod_time
+              oplen += templen;
+
+              read_unsigned_LEB_128(start, &templen);   // filelength
+              oplen += templen;
+
+              files_.push_back(std::pair<int, std::string>(dirindex,
+							   filename));
+            }
+            break;
+          }
+      }
+      break;
+
+    default:
+      {
+        // Ignore unknown opcode  silently
+        for (int i = 0; i < header_.std_opcode_lengths[opcode]; i++)
+          {
+            size_t templen;
+            read_unsigned_LEB_128(start, &templen);
+            start += templen;
+            oplen += templen;
+          }
+      }
+      break;
+  }
+  *len = oplen;
+  return false;
+}
+
+// Read the debug information at LINEPTR and store it in the line
+// number map.
+
+unsigned const char*
+Dwarf_line_info::read_lines(int size, bool big_endian,
+                            unsigned const char* lineptr)
+{
+  struct LineStateMachine lsm;
+
+  // LENGTHSTART is the place the length field is based on.  It is the
+  // point in the header after the initial length field.
+  const unsigned char* lengthstart = buffer_;
+
+  // In 64 bit dwarf, the initial length is 12 bytes, because of the
+  // 0xffffffff at the start.
+  if (header_.offset_size == 8)
+    lengthstart += 12;
+  else
+    lengthstart += 4;
+
+  while (lineptr < lengthstart + header_.total_length)
+    {
+      ResetLineStateMachine(&lsm, header_.default_is_stmt);
+      while (!lsm.end_sequence)
+        {
+          size_t oplength;
+          bool add_line = this->process_one_opcode(size, big_endian,
+                                                   lineptr, &lsm, &oplength);
+          if (add_line)
+            {
+              Offset_to_lineno_entry entry
+                  = { lsm.address, lsm.file_num, lsm.line_num };
+              line_number_map_[lsm.shndx].push_back(entry);
+            }
+          lineptr += oplength;
+        }
+    }
+
+  return lengthstart + header_.total_length;
+}
+
+// Called after all line numbers have been read.
+
+void
+Dwarf_line_info::finalize_line_number_map()
+{
+  for (Lineno_map::iterator it = line_number_map_.begin();
+       it != line_number_map_.end();
+       ++it)
+    // Each vector needs to be sorted by offset.
+    sort(it->second.begin(), it->second.end());
+}
+
+// Return a string for a file name and line number.
+
+std::string
+Dwarf_line_info::addr2line(unsigned int shndx, off_t offset)
+{
+  const Offset_to_lineno_entry lookup_key = { offset, 0, 0 };
+  std::vector<Offset_to_lineno_entry>& offsets = line_number_map_[shndx];
+  std::vector<Offset_to_lineno_entry>::const_iterator it
+      = std::lower_bound(offsets.begin(), offsets.end(), lookup_key);
+
+  // If we found an exact match, great, otherwise find the last entry
+  // before the passed-in offset.
+  if (it->offset > offset)
+    {
+      if (it == offsets.begin())
+        return "";
+      --it;
+      gold_assert(it->offset < offset);
+    }
+
+  // Convert the file_num + line_num into a string.
+  std::string ret;
+  gold_assert(it->file_num < static_cast<int>(files_.size()));
+  const std::pair<int, std::string>& filename_pair = files_[it->file_num];
+  gold_assert(filename_pair.first < static_cast<int>(directories_.size()));
+  const std::string& dirname = directories_[filename_pair.first];
+  const std::string& filename = filename_pair.second;
+  if (!dirname.empty())
+    {
+      ret += dirname;
+      ret += "/";
+    }
+  ret += filename;
+  if (ret.empty())
+    ret = "(unknown)";
+
+  char buffer[64];   // enough to hold a line number
+  snprintf(buffer, sizeof(buffer), "%d", it->line_num);
+  ret += ":";
+  ret += buffer;
+
+  return ret;
+}
+
+#ifdef HAVE_TARGET_32_LITTLE
+template
+const unsigned char*
+Dwarf_line_info::read_header_prolog<32, false>(const unsigned char* lineptr);
+#endif
+
+#ifdef HAVE_TARGET_32_BIG
+template
+const unsigned char*
+Dwarf_line_info::read_header_prolog<32, true>(const unsigned char* lineptr);
+#endif
+
+#ifdef HAVE_TARGET_64_LITTLE
+template
+const unsigned char*
+Dwarf_line_info::read_header_prolog<64, false>(const unsigned char* lineptr);
+#endif
+
+#ifdef HAVE_TARGET_64_BIG
+template
+const unsigned char*
+Dwarf_line_info::read_header_prolog<64, true>(const unsigned char* lineptr);
+#endif
+
+} // End namespace gold.