Add support for parsing the DW_AT_ranges attributes

This enables the DWARF reader to properly parse DW_AT_ranges attributes
in compilation units and functions. Code covered by a function is now
represented by a vector of ranges instead of a single contiguous range
and DW_AT_ranges entries are used to populate it. All the code and tests
that assumed functions to be contiguous entities has been updated to
reflect the change. DW_AT_ranges attributes found in compilation units
are parsed but no data is generated for them as it is not currently needed.

BUG=754

Change-Id: I310391b525aaba0dd329f1e3187486f2e0c6d442
Reviewed-on: https://chromium-review.googlesource.com/1124721
Reviewed-by: Ted Mielczarek <ted.mielczarek@gmail.com>

1 files changed, 40 insertions, 1 deletions

diff --git a/src/common/linux/dump_symbols.cc b/src/common/linux/dump_symbols.cc
index e7a74ccb..1110cb9d 100644
--- a/src/common/linux/dump_symbols.cc
+++ b/src/common/linux/dump_symbols.cc
@@ -58,6 +58,7 @@
 #include "common/dwarf_cfi_to_module.h"
 #include "common/dwarf_cu_to_module.h"
 #include "common/dwarf_line_to_module.h"
+#include "common/dwarf_range_list_handler.h"
 #include "common/linux/crc32.h"
 #include "common/linux/eintr_wrapper.h"
 #include "common/linux/elfutils.h"
@@ -81,6 +82,7 @@ using google_breakpad::DumpOptions;
 using google_breakpad::DwarfCFIToModule;
 using google_breakpad::DwarfCUToModule;
 using google_breakpad::DwarfLineToModule;
+using google_breakpad::DwarfRangeListHandler;
 using google_breakpad::ElfClass;
 using google_breakpad::ElfClass32;
 using google_breakpad::ElfClass64;
@@ -207,6 +209,30 @@ bool LoadStabs(const typename ElfClass::Ehdr* elf_header,
 }
 #endif  // NO_STABS_SUPPORT
 
+// A range handler that accepts rangelist data parsed by
+// dwarf2reader::RangeListReader and populates a range vector (typically
+// owned by a function) with the results.
+class DumperRangesHandler : public DwarfCUToModule::RangesHandler {
+ public:
+  DumperRangesHandler(const uint8_t *buffer, uint64 size,
+                      dwarf2reader::ByteReader* reader)
+      : buffer_(buffer), size_(size), reader_(reader) { }
+
+  bool ReadRanges(uint64 offset, Module::Address base_address,
+                  vector<Module::Range>* ranges) {
+    DwarfRangeListHandler handler(base_address, ranges);
+    dwarf2reader::RangeListReader rangelist_reader(buffer_, size_, reader_,
+                                                   &handler);
+
+    return rangelist_reader.ReadRangeList(offset);
+  }
+
+ private:
+  const uint8_t *buffer_;
+  uint64 size_;
+  dwarf2reader::ByteReader* reader_;
+};
+
 // A line-to-module loader that accepts line number info parsed by
 // dwarf2reader::LineInfo and populates a Module and a line vector
 // with the results.
@@ -261,6 +287,18 @@ bool LoadDwarf(const string& dwarf_filename,
     file_context.AddSectionToSectionMap(name, contents, section->sh_size);
   }
 
+  // Optional .debug_ranges reader
+  scoped_ptr<DumperRangesHandler> ranges_handler;
+  dwarf2reader::SectionMap::const_iterator ranges_entry =
+      file_context.section_map().find(".debug_ranges");
+  if (ranges_entry != file_context.section_map().end()) {
+    const std::pair<const uint8_t *, uint64>& ranges_section =
+      ranges_entry->second;
+    ranges_handler.reset(
+      new DumperRangesHandler(ranges_section.first, ranges_section.second,
+                              &byte_reader));
+  }
+
   // Parse all the compilation units in the .debug_info section.
   DumperLineToModule line_to_module(&byte_reader);
   dwarf2reader::SectionMap::const_iterator debug_info_entry =
@@ -276,7 +314,8 @@ bool LoadDwarf(const string& dwarf_filename,
     // Make a handler for the root DIE that populates MODULE with the
     // data that was found.
     DwarfCUToModule::WarningReporter reporter(dwarf_filename, offset);
-    DwarfCUToModule root_handler(&file_context, &line_to_module, &reporter);
+    DwarfCUToModule root_handler(&file_context, &line_to_module,
+                                 ranges_handler.get(), &reporter);
     // Make a Dwarf2Handler that drives the DIEHandler.
     dwarf2reader::DIEDispatcher die_dispatcher(&root_handler);
     // Make a DWARF parser for the compilation unit at OFFSET.