Add debug fission support.

This added debug fission support.
It tries to find the dwp file from the debug dir /usr/lib/debug/*/debug
and read symbols from them.

Most of this patch comes from
https://critique.corp.google.com/#review/52048295
and some fixes after that.
The elf_reader.cc comes from TOT google code. I just
removed some google dependency.

Current problems from this patch
1: Some type mismatch: from uint8_t * to char *.
2: Some hack to find the .dwp file. (replace .debug with .dwp)

BUG=chromium:604440
R=dehao@google.com, ivanpe@chromium.org

Review URL: https://codereview.chromium.org/1884283002 .

Makefile.am

@@ -564,6 +564,7 @@ src_tools_linux_dump_syms_dump_syms_SOURCES = \
 	src/common/dwarf/bytereader.cc \
 	src/common/dwarf/dwarf2diehandler.cc \
 	src/common/dwarf/dwarf2reader.cc \
+	src/common/dwarf/elf_reader.cc \
 	src/common/linux/crc32.cc \
 	src/common/linux/dump_symbols.cc \
 	src/common/linux/elf_symbols_to_module.cc \
@@ -601,6 +602,7 @@ src_tools_mac_dump_syms_dump_syms_mac_SOURCES = \
 	src/common/dwarf/bytereader.cc \
 	src/common/dwarf/dwarf2diehandler.cc \
 	src/common/dwarf/dwarf2reader.cc \
+	src/common/dwarf/elf_reader.cc \
 	src/common/mac/arch_utilities.cc \
 	src/common/mac/dump_syms.cc \
 	src/common/mac/file_id.cc \
@@ -636,6 +638,7 @@ src_common_dumper_unittest_SOURCES = \
 	src/common/dwarf/dwarf2diehandler.cc \
 	src/common/dwarf/dwarf2diehandler_unittest.cc \
 	src/common/dwarf/dwarf2reader.cc \
+	src/common/dwarf/elf_reader.cc \
 	src/common/dwarf/dwarf2reader_cfi_unittest.cc \
 	src/common/dwarf/dwarf2reader_die_unittest.cc \
 	src/common/linux/crc32.cc \
@@ -678,6 +681,7 @@ src_common_mac_macho_reader_unittest_SOURCES = \
 	src/common/dwarf/cfi_assembler.cc \
 	src/common/dwarf/dwarf2diehandler.cc \
 	src/common/dwarf/dwarf2reader.cc \
+	src/common/dwarf/elf_reader.cc \
 	src/common/mac/arch_utilities.cc \
 	src/common/mac/file_id.cc \
 	src/common/mac/macho_id.cc \

Makefile.in

@@ -691,6 +691,7 @@ am__src_common_dumper_unittest_SOURCES_DIST =  \
 	src/common/dwarf/dwarf2reader.cc \
 	src/common/dwarf/dwarf2reader_cfi_unittest.cc \
 	src/common/dwarf/dwarf2reader_die_unittest.cc \
+	src/common/dwarf/elf_reader.cc \
 	src/common/linux/crc32.cc src/common/linux/dump_symbols.cc \
 	src/common/linux/dump_symbols_unittest.cc \
 	src/common/linux/elf_core_dump.cc \
@@ -732,6 +733,7 @@ am__src_common_dumper_unittest_SOURCES_DIST =  \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/src_common_dumper_unittest-dwarf2reader.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/src_common_dumper_unittest-dwarf2reader_cfi_unittest.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/src_common_dumper_unittest-dwarf2reader_die_unittest.$(OBJEXT) \
+@DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@  src/common/dwarf/src_common_dumper_unittest-elf_reader.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/linux/src_common_dumper_unittest-crc32.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/linux/src_common_dumper_unittest-dump_symbols.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/linux/src_common_dumper_unittest-dump_symbols_unittest.$(OBJEXT) \
@@ -767,6 +769,7 @@ am__src_common_mac_macho_reader_unittest_SOURCES_DIST =  \
 	src/common/dwarf/cfi_assembler.cc \
 	src/common/dwarf/dwarf2diehandler.cc \
 	src/common/dwarf/dwarf2reader.cc \
+	src/common/dwarf/elf_reader.cc \
 	src/common/mac/arch_utilities.cc src/common/mac/file_id.cc \
 	src/common/mac/macho_id.cc src/common/mac/macho_reader.cc \
 	src/common/mac/macho_reader_unittest.cc \
@@ -785,6 +788,7 @@ am__src_common_mac_macho_reader_unittest_SOURCES_DIST =  \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/src_common_mac_macho_reader_unittest-cfi_assembler.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/src_common_mac_macho_reader_unittest-dwarf2diehandler.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/src_common_mac_macho_reader_unittest-dwarf2reader.$(OBJEXT) \
+@DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@  src/common/dwarf/src_common_mac_macho_reader_unittest-elf_reader.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/mac/src_common_mac_macho_reader_unittest-arch_utilities.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/mac/src_common_mac_macho_reader_unittest-file_id.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/mac/src_common_mac_macho_reader_unittest-macho_id.$(OBJEXT) \
@@ -1343,7 +1347,8 @@ am__src_tools_linux_dump_syms_dump_syms_SOURCES_DIST =  \
 	src/common/module.cc src/common/stabs_reader.cc \
 	src/common/stabs_to_module.cc src/common/dwarf/bytereader.cc \
 	src/common/dwarf/dwarf2diehandler.cc \
-	src/common/dwarf/dwarf2reader.cc src/common/linux/crc32.cc \
+	src/common/dwarf/dwarf2reader.cc \
+	src/common/dwarf/elf_reader.cc src/common/linux/crc32.cc \
 	src/common/linux/dump_symbols.cc \
 	src/common/linux/elf_symbols_to_module.cc \
 	src/common/linux/elfutils.cc src/common/linux/file_id.cc \
@@ -1361,6 +1366,7 @@ am__src_tools_linux_dump_syms_dump_syms_SOURCES_DIST =  \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/bytereader.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/dwarf2diehandler.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/dwarf2reader.$(OBJEXT) \
+@DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@  src/common/dwarf/elf_reader.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/linux/crc32.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/linux/dump_symbols.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/linux/elf_symbols_to_module.$(OBJEXT) \
@@ -1415,6 +1421,7 @@ am__src_tools_mac_dump_syms_dump_syms_mac_SOURCES_DIST =  \
 	src/common/dwarf/bytereader.cc \
 	src/common/dwarf/dwarf2diehandler.cc \
 	src/common/dwarf/dwarf2reader.cc \
+	src/common/dwarf/elf_reader.cc \
 	src/common/mac/arch_utilities.cc src/common/mac/dump_syms.cc \
 	src/common/mac/file_id.cc src/common/mac/macho_id.cc \
 	src/common/mac/macho_reader.cc \
@@ -1432,6 +1439,7 @@ am__src_tools_mac_dump_syms_dump_syms_mac_SOURCES_DIST =  \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-bytereader.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-dwarf2diehandler.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-dwarf2reader.$(OBJEXT) \
+@DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@  src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/mac/src_tools_mac_dump_syms_dump_syms_mac-arch_utilities.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/mac/src_tools_mac_dump_syms_dump_syms_mac-dump_syms.$(OBJEXT) \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/mac/src_tools_mac_dump_syms_dump_syms_mac-file_id.$(OBJEXT) \
@@ -2306,6 +2314,7 @@ TESTS = $(check_PROGRAMS) $(check_SCRIPTS)
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/bytereader.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/dwarf2diehandler.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/dwarf2reader.cc \
+@DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@  src/common/dwarf/elf_reader.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/linux/crc32.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/linux/dump_symbols.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/linux/elf_symbols_to_module.cc \
@@ -2343,6 +2352,7 @@ TESTS = $(check_PROGRAMS) $(check_SCRIPTS)
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/bytereader.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/dwarf2diehandler.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/dwarf2reader.cc \
+@DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@  src/common/dwarf/elf_reader.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/mac/arch_utilities.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/mac/dump_syms.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/mac/file_id.cc \
@@ -2381,6 +2391,7 @@ TESTS = $(check_PROGRAMS) $(check_SCRIPTS)
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/dwarf2reader.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/dwarf2reader_cfi_unittest.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/dwarf2reader_die_unittest.cc \
+@DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@  src/common/dwarf/elf_reader.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/linux/crc32.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/linux/dump_symbols.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/linux/dump_symbols_unittest.cc \
@@ -2423,6 +2434,7 @@ TESTS = $(check_PROGRAMS) $(check_SCRIPTS)
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/cfi_assembler.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/dwarf2diehandler.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/dwarf/dwarf2reader.cc \
+@DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@  src/common/dwarf/elf_reader.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/mac/arch_utilities.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/mac/file_id.cc \
 @DISABLE_TOOLS_FALSE@@LINUX_HOST_TRUE@	src/common/mac/macho_id.cc \
@@ -3790,6 +3802,9 @@ src/common/dwarf/src_common_dumper_unittest-dwarf2reader_cfi_unittest.$(OBJEXT):
 src/common/dwarf/src_common_dumper_unittest-dwarf2reader_die_unittest.$(OBJEXT):  \
 	src/common/dwarf/$(am__dirstamp) \
 	src/common/dwarf/$(DEPDIR)/$(am__dirstamp)
+src/common/dwarf/src_common_dumper_unittest-elf_reader.$(OBJEXT):  \
+        src/common/dwarf/$(am__dirstamp) \
+        src/common/dwarf/$(DEPDIR)/$(am__dirstamp)
 src/common/linux/src_common_dumper_unittest-crc32.$(OBJEXT):  \
 	src/common/linux/$(am__dirstamp) \
 	src/common/linux/$(DEPDIR)/$(am__dirstamp)
@@ -3890,6 +3905,9 @@ src/common/dwarf/src_common_mac_macho_reader_unittest-dwarf2diehandler.$(OBJEXT)
 src/common/dwarf/src_common_mac_macho_reader_unittest-dwarf2reader.$(OBJEXT):  \
 	src/common/dwarf/$(am__dirstamp) \
 	src/common/dwarf/$(DEPDIR)/$(am__dirstamp)
+src/common/dwarf/src_common_mac_macho_reader_unittest-elf_reader.$(OBJEXT):  \
+        src/common/dwarf/$(am__dirstamp) \
+        src/common/dwarf/$(DEPDIR)/$(am__dirstamp)
 src/common/mac/$(am__dirstamp):
 	@$(MKDIR_P) src/common/mac
 	@: > src/common/mac/$(am__dirstamp)
@@ -4222,6 +4240,9 @@ src/common/dwarf/dwarf2diehandler.$(OBJEXT):  \
 src/common/dwarf/dwarf2reader.$(OBJEXT):  \
 	src/common/dwarf/$(am__dirstamp) \
 	src/common/dwarf/$(DEPDIR)/$(am__dirstamp)
+src/common/dwarf/elf_reader.$(OBJEXT):  \
+        src/common/dwarf/$(am__dirstamp) \
+        src/common/dwarf/$(DEPDIR)/$(am__dirstamp)
 src/common/linux/crc32.$(OBJEXT): src/common/linux/$(am__dirstamp) \
 	src/common/linux/$(DEPDIR)/$(am__dirstamp)
 src/common/linux/dump_symbols.$(OBJEXT):  \
@@ -4322,6 +4343,9 @@ src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-dwarf2diehandler.$(OBJEXT
 src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-dwarf2reader.$(OBJEXT):  \
 	src/common/dwarf/$(am__dirstamp) \
 	src/common/dwarf/$(DEPDIR)/$(am__dirstamp)
+src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.$(OBJEXT):  \
+        src/common/dwarf/$(am__dirstamp) \
+        src/common/dwarf/$(DEPDIR)/$(am__dirstamp)
 src/common/mac/src_tools_mac_dump_syms_dump_syms_mac-arch_utilities.$(OBJEXT):  \
 	src/common/mac/$(am__dirstamp) \
 	src/common/mac/$(DEPDIR)/$(am__dirstamp)
@@ -4472,6 +4496,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/bytereader.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/dwarf2diehandler.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/dwarf2reader.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/elf_reader.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_common_dumper_unittest-bytereader.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_common_dumper_unittest-bytereader_unittest.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_common_dumper_unittest-cfi_assembler.Po@am__quote@
@@ -4480,13 +4505,16 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_common_dumper_unittest-dwarf2reader.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_common_dumper_unittest-dwarf2reader_cfi_unittest.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_common_dumper_unittest-dwarf2reader_die_unittest.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_common_dumper_unittest-elf_reader.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_common_mac_macho_reader_unittest-bytereader.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_common_mac_macho_reader_unittest-cfi_assembler.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_common_mac_macho_reader_unittest-dwarf2diehandler.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_common_mac_macho_reader_unittest-dwarf2reader.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_common_mac_macho_reader_unittest-elf_reader.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-bytereader.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-dwarf2diehandler.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-dwarf2reader.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@src/common/dwarf/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/linux/$(DEPDIR)/crc32.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/linux/$(DEPDIR)/dump_symbols.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@src/common/linux/$(DEPDIR)/elf_core_dump.Po@am__quote@
@@ -6707,6 +6735,20 @@ src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-dwarf2reader.obj: src/com
 @AMDEP_TRUE@@am__fastdepCXX_FALSE@	DEPDIR=$(DEPDIR) $(CXXDEPMODE) $(depcomp) @AMDEPBACKSLASH@
 @am__fastdepCXX_FALSE@	$(AM_V_CXX@am__nodep@)$(CXX) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(src_tools_mac_dump_syms_dump_syms_mac_CXXFLAGS) $(CXXFLAGS) -c -o src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-dwarf2reader.obj `if test -f 'src/common/dwarf/dwarf2reader.cc'; then $(CYGPATH_W) 'src/common/dwarf/dwarf2reader.cc'; else $(CYGPATH_W) '$(srcdir)/src/common/dwarf/dwarf2reader.cc'; fi`
 
+src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.o: src/common/dwarf/elf_reader.cc
+@am__fastdepCXX_TRUE@	$(AM_V_CXX)$(CXX) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(src_tools_mac_dump_syms_dump_syms_mac_CXXFLAGS) $(CXXFLAGS) -MT src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.o -MD -MP -MF src/common/dwarf/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.Tpo -c -o src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.o `test -f 'src/common/dwarf/elf_reader.cc' || echo '$(srcdir)/'`src/common/dwarf/elf_reader.cc
+@am__fastdepCXX_TRUE@	$(AM_V_at)$(am__mv) src/common/dwarf/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.Tpo src/common/dwarf/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.Po
+@AMDEP_TRUE@@am__fastdepCXX_FALSE@	$(AM_V_CXX)source='src/common/dwarf/elf_reader.cc' object='src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.o' libtool=no @AMDEPBACKSLASH@
+@AMDEP_TRUE@@am__fastdepCXX_FALSE@	DEPDIR=$(DEPDIR) $(CXXDEPMODE) $(depcomp) @AMDEPBACKSLASH@
+@am__fastdepCXX_FALSE@	$(AM_V_CXX@am__nodep@)$(CXX) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(src_tools_mac_dump_syms_dump_syms_mac_CXXFLAGS) $(CXXFLAGS) -c -o src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.o `test -f 'src/common/dwarf/elf_reader.cc' || echo '$(srcdir)/'`src/common/dwarf/elf_reader.cc
+
+src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.obj: src/common/dwarf/elf_reader.cc
+@am__fastdepCXX_TRUE@	$(AM_V_CXX)$(CXX) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(src_tools_mac_dump_syms_dump_syms_mac_CXXFLAGS) $(CXXFLAGS) -MT src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.obj -MD -MP -MF src/common/dwarf/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.Tpo -c -o src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.obj `if test -f 'src/common/dwarf/elf_reader.cc'; then $(CYGPATH_W) 'src/common/dwarf/elf_reader.cc'; else $(CYGPATH_W) '$(srcdir)/src/common/dwarf/elf_reader.cc'; fi`
+@am__fastdepCXX_TRUE@	$(AM_V_at)$(am__mv) src/common/dwarf/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.Tpo src/common/dwarf/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.Po
+@AMDEP_TRUE@@am__fastdepCXX_FALSE@	$(AM_V_CXX)source='src/common/dwarf/elf_reader.cc' object='src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.obj' libtool=no @AMDEPBACKSLASH@
+@AMDEP_TRUE@@am__fastdepCXX_FALSE@	DEPDIR=$(DEPDIR) $(CXXDEPMODE) $(depcomp) @AMDEPBACKSLASH@
+@am__fastdepCXX_FALSE@	$(AM_V_CXX@am__nodep@)$(CXX) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(src_tools_mac_dump_syms_dump_syms_mac_CXXFLAGS) $(CXXFLAGS) -c -o src/common/dwarf/src_tools_mac_dump_syms_dump_syms_mac-elf_reader.obj `if test -f 'src/common/dwarf/elf_reader.cc'; then $(CYGPATH_W) 'src/common/dwarf/elf_reader.cc'; else $(CYGPATH_W) '$(srcdir)/src/common/dwarf/elf_reader.cc'; fi`
+
 src/common/mac/src_tools_mac_dump_syms_dump_syms_mac-arch_utilities.o: src/common/mac/arch_utilities.cc
 @am__fastdepCXX_TRUE@	$(AM_V_CXX)$(CXX) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(src_tools_mac_dump_syms_dump_syms_mac_CXXFLAGS) $(CXXFLAGS) -MT src/common/mac/src_tools_mac_dump_syms_dump_syms_mac-arch_utilities.o -MD -MP -MF src/common/mac/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-arch_utilities.Tpo -c -o src/common/mac/src_tools_mac_dump_syms_dump_syms_mac-arch_utilities.o `test -f 'src/common/mac/arch_utilities.cc' || echo '$(srcdir)/'`src/common/mac/arch_utilities.cc
 @am__fastdepCXX_TRUE@	$(AM_V_at)$(am__mv) src/common/mac/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-arch_utilities.Tpo src/common/mac/$(DEPDIR)/src_tools_mac_dump_syms_dump_syms_mac-arch_utilities.Po

src/common/common.gyp

@@ -75,6 +75,8 @@
         'dwarf/dwarf2reader.cc',
         'dwarf/dwarf2reader.h',
         'dwarf/dwarf2reader_test_common.h',
+	'dwarf/elf_reader.cc',
+	'dwarf/elf_reader.h',
         'dwarf/functioninfo.cc',
         'dwarf/functioninfo.h',
         'dwarf/line_state_machine.h',

src/common/dwarf/bytereader.cc

@@ -243,4 +243,8 @@ uint64 ByteReader::ReadEncodedPointer(const uint8_t *buffer,
   return pointer;
 }
 
+Endianness ByteReader::GetEndianness() const {
+  return endian_;
+}
+
 }  // namespace dwarf2reader

src/common/dwarf/bytereader.h

@@ -280,6 +280,7 @@ class ByteReader {
                             DwarfPointerEncoding encoding,
                             size_t *len) const;
 
+  Endianness GetEndianness() const;
  private:
 
   // Function pointer type for our address and offset readers.

src/common/dwarf/dwarf2enums.h

@@ -149,7 +149,10 @@ enum DwarfForm {
   DW_FORM_sec_offset = 0x17,
   DW_FORM_exprloc = 0x18,
   DW_FORM_flag_present = 0x19,
-  DW_FORM_ref_sig8 = 0x20
+  DW_FORM_ref_sig8 = 0x20,
+  // Extensions for Fission.  See http://gcc.gnu.org/wiki/DebugFission.
+  DW_FORM_GNU_addr_index = 0x1f01,
+  DW_FORM_GNU_str_index = 0x1f02
 };
 
 // Attribute names and codes
@@ -264,6 +267,13 @@ enum DwarfAttribute {
   DW_AT_body_begin = 0x2105,
   DW_AT_body_end   = 0x2106,
   DW_AT_GNU_vector = 0x2107,
+  // Extensions for Fission.  See http://gcc.gnu.org/wiki/DebugFission.
+  DW_AT_GNU_dwo_name = 0x2130,
+  DW_AT_GNU_dwo_id = 0x2131,
+  DW_AT_GNU_ranges_base = 0x2132,
+  DW_AT_GNU_addr_base = 0x2133,
+  DW_AT_GNU_pubnames = 0x2134,
+  DW_AT_GNU_pubtypes = 0x2135,
   // VMS extensions.
   DW_AT_VMS_rtnbeg_pd_address = 0x2201,
   // UPC extension.
@@ -491,7 +501,22 @@ enum DwarfOpcode {
   DW_OP_lo_user                      =0xe0,
   DW_OP_hi_user                      =0xff,  
   // GNU extensions
-  DW_OP_GNU_push_tls_address         =0xe0
+  DW_OP_GNU_push_tls_address         =0xe0,
+  // Extensions for Fission.  See http://gcc.gnu.org/wiki/DebugFission.
+  DW_OP_GNU_addr_index               =0xfb,
+  DW_OP_GNU_const_index              =0xfc
+};
+
+// Section identifiers for DWP files
+enum DwarfSectionId {
+  DW_SECT_INFO = 1,
+  DW_SECT_TYPES = 2,
+  DW_SECT_ABBREV = 3,
+  DW_SECT_LINE = 4,
+  DW_SECT_LOC = 5,
+  DW_SECT_STR_OFFSETS = 6,
+  DW_SECT_MACINFO = 7,
+  DW_SECT_MACRO = 8
 };
 
 // Source languages.  These are values for DW_AT_language.

src/common/dwarf/dwarf2reader.cc

@@ -44,6 +44,8 @@
 #include <string>
 #include <utility>
 
+#include <sys/stat.h>
+
 #include "common/dwarf/bytereader-inl.h"
 #include "common/dwarf/bytereader.h"
 #include "common/dwarf/line_state_machine.h"
@@ -51,11 +53,38 @@
 
 namespace dwarf2reader {
 
-CompilationUnit::CompilationUnit(const SectionMap& sections, uint64 offset,
+CompilationUnit::CompilationUnit(const string& path,
+                                 const SectionMap& sections, uint64 offset,
                                  ByteReader* reader, Dwarf2Handler* handler)
-    : offset_from_section_start_(offset), reader_(reader),
+    : path_(path), offset_from_section_start_(offset), reader_(reader),
-      sections_(sections), handler_(handler), abbrevs_(NULL),
+      sections_(sections), handler_(handler), abbrevs_(),
-      string_buffer_(NULL), string_buffer_length_(0) {}
+      string_buffer_(NULL), string_buffer_length_(0),
+      str_offsets_buffer_(NULL), str_offsets_buffer_length_(0),
+      addr_buffer_(NULL), addr_buffer_length_(0),
+      is_split_dwarf_(false), dwo_id_(0), dwo_name_(),
+      skeleton_dwo_id_(0), ranges_base_(0), addr_base_(0),
+      have_checked_for_dwp_(false), dwp_path_(),
+      dwp_byte_reader_(), dwp_reader_() {}
+
+// Initialize a compilation unit from a .dwo or .dwp file.
+// In this case, we need the .debug_addr section from the
+// executable file that contains the corresponding skeleton
+// compilation unit.  We also inherit the Dwarf2Handler from
+// the executable file, and call it as if we were still
+// processing the original compilation unit.
+
+void CompilationUnit::SetSplitDwarf(const uint8_t* addr_buffer,
+                                    uint64 addr_buffer_length,
+                                    uint64 addr_base,
+                                    uint64 ranges_base,
+                                    uint64 dwo_id) {
+  is_split_dwarf_ = true;
+  addr_buffer_ = addr_buffer;
+  addr_buffer_length_ = addr_buffer_length;
+  addr_base_ = addr_base;
+  ranges_base_ = ranges_base;
+  skeleton_dwo_id_ = dwo_id;
+}
 
 // Read a DWARF2/3 abbreviation section.
 // Each abbrev consists of a abbreviation number, a tag, a byte
@@ -174,6 +203,8 @@ const uint8_t *CompilationUnit::SkipAttribute(const uint8_t *start,
       return start + strlen(reinterpret_cast<const char *>(start)) + 1;
     case DW_FORM_udata:
     case DW_FORM_ref_udata:
+    case DW_FORM_GNU_str_index:
+    case DW_FORM_GNU_addr_index:
       reader_->ReadUnsignedLEB128(start, &len);
       return start + len;
 
@@ -296,9 +327,31 @@ uint64 CompilationUnit::Start() {
     string_buffer_length_ = iter->second.second;
   }
 
+  // Set the string offsets section if we have one.
+  iter = sections_.find(".debug_str_offsets");
+  if (iter != sections_.end()) {
+    str_offsets_buffer_ = iter->second.first;
+    str_offsets_buffer_length_ = iter->second.second;
+  }
+
+  // Set the address section if we have one.
+  iter = sections_.find(".debug_addr");
+  if (iter != sections_.end()) {
+    addr_buffer_ = iter->second.first;
+    addr_buffer_length_ = iter->second.second;
+  }
+
   // Now that we have our abbreviations, start processing DIE's.
   ProcessDIEs();
 
+  // If this is a skeleton compilation unit generated with split DWARF,
+  // and the client needs the full debug info, we need to find the full
+  // compilation unit in a .dwo or .dwp file.
+  if (!is_split_dwarf_
+      && dwo_name_ != NULL
+      && handler_->NeedSplitDebugInfo())
+    ProcessSplitDwarf();
+
   return ourlength;
 }
 
@@ -320,48 +373,46 @@ const uint8_t *CompilationUnit::ProcessAttribute(
       return ProcessAttribute(dieoffset, start, attr, form);
 
     case DW_FORM_flag_present:
-      handler_->ProcessAttributeUnsigned(dieoffset, attr, form, 1);
+      ProcessAttributeUnsigned(dieoffset, attr, form, 1);
       return start;
     case DW_FORM_data1:
     case DW_FORM_flag:
-      handler_->ProcessAttributeUnsigned(dieoffset, attr, form,
+      ProcessAttributeUnsigned(dieoffset, attr, form,
-                                         reader_->ReadOneByte(start));
+                               reader_->ReadOneByte(start));
       return start + 1;
     case DW_FORM_data2:
-      handler_->ProcessAttributeUnsigned(dieoffset, attr, form,
+      ProcessAttributeUnsigned(dieoffset, attr, form,
-                                         reader_->ReadTwoBytes(start));
+                               reader_->ReadTwoBytes(start));
       return start + 2;
     case DW_FORM_data4:
-      handler_->ProcessAttributeUnsigned(dieoffset, attr, form,
+      ProcessAttributeUnsigned(dieoffset, attr, form,
-                                         reader_->ReadFourBytes(start));
+                               reader_->ReadFourBytes(start));
       return start + 4;
     case DW_FORM_data8:
-      handler_->ProcessAttributeUnsigned(dieoffset, attr, form,
+      ProcessAttributeUnsigned(dieoffset, attr, form,
-                                         reader_->ReadEightBytes(start));
+                               reader_->ReadEightBytes(start));
       return start + 8;
     case DW_FORM_string: {
       const char *str = reinterpret_cast<const char *>(start);
-      handler_->ProcessAttributeString(dieoffset, attr, form,
+      ProcessAttributeString(dieoffset, attr, form, str);
-                                       str);
       return start + strlen(str) + 1;
     }
     case DW_FORM_udata:
-      handler_->ProcessAttributeUnsigned(dieoffset, attr, form,
+      ProcessAttributeUnsigned(dieoffset, attr, form,
-                                         reader_->ReadUnsignedLEB128(start,
+                               reader_->ReadUnsignedLEB128(start, &len));
-                                                                     &len));
       return start + len;
 
     case DW_FORM_sdata:
-      handler_->ProcessAttributeSigned(dieoffset, attr, form,
+      ProcessAttributeSigned(dieoffset, attr, form,
-                                      reader_->ReadSignedLEB128(start, &len));
+                             reader_->ReadSignedLEB128(start, &len));
       return start + len;
     case DW_FORM_addr:
-      handler_->ProcessAttributeUnsigned(dieoffset, attr, form,
+      ProcessAttributeUnsigned(dieoffset, attr, form,
-                                         reader_->ReadAddress(start));
+                               reader_->ReadAddress(start));
       return start + reader_->AddressSize();
     case DW_FORM_sec_offset:
-      handler_->ProcessAttributeUnsigned(dieoffset, attr, form,
+      ProcessAttributeUnsigned(dieoffset, attr, form,
-                                         reader_->ReadOffset(start));
+                               reader_->ReadOffset(start));
       return start + reader_->OffsetSize();
 
     case DW_FORM_ref1:
@@ -441,10 +492,32 @@ const uint8_t *CompilationUnit::ProcessAttribute(
       assert(string_buffer_ + offset < string_buffer_ + string_buffer_length_);
 
       const char *str = reinterpret_cast<const char *>(string_buffer_ + offset);
-      handler_->ProcessAttributeString(dieoffset, attr, form,
+      ProcessAttributeString(dieoffset, attr, form, str);
-                                       str);
       return start + reader_->OffsetSize();
     }
+
+    case DW_FORM_GNU_str_index: {
+      uint64 str_index = reader_->ReadUnsignedLEB128(start, &len);
+      const uint8_t* offset_ptr =
+          str_offsets_buffer_ + str_index * reader_->OffsetSize();
+      const uint64 offset = reader_->ReadOffset(offset_ptr);
+      if (offset >= string_buffer_length_) {
+        return NULL;
+      }
+
+      const char* str = reinterpret_cast<const char *>(string_buffer_) + offset;
+      ProcessAttributeString(dieoffset, attr, form, str);
+      return start + len;
+      break;
+    }
+    case DW_FORM_GNU_addr_index: {
+      uint64 addr_index = reader_->ReadUnsignedLEB128(start, &len);
+      const uint8_t* addr_ptr =
+          addr_buffer_ + addr_base_ + addr_index * reader_->AddressSize();
+      ProcessAttributeUnsigned(dieoffset, attr, form,
+                               reader_->ReadAddress(addr_ptr));
+      return start + len;
+    }
   }
   fprintf(stderr, "Unhandled form type\n");
   return NULL;
@@ -458,6 +531,16 @@ const uint8_t *CompilationUnit::ProcessDIE(uint64 dieoffset,
        i++)  {
     start = ProcessAttribute(dieoffset, start, i->first, i->second);
   }
+
+  // If this is a compilation unit in a split DWARF object, verify that
+  // the dwo_id matches. If it does not match, we will ignore this
+  // compilation unit.
+  if (abbrev.tag == DW_TAG_compile_unit
+      && is_split_dwarf_
+      && dwo_id_ != skeleton_dwo_id_) {
+    return NULL;
+  }
+
   return start;
 }
 
@@ -515,6 +598,307 @@ void CompilationUnit::ProcessDIEs() {
   }
 }
 
+// Check for a valid ELF file and return the Address size.
+// Returns 0 if not a valid ELF file.
+inline int GetElfWidth(const ElfReader& elf) {
+  if (elf.IsElf32File())
+    return 4;
+  if (elf.IsElf64File())
+    return 8;
+  return 0;
+}
+
+void CompilationUnit::ProcessSplitDwarf() {
+  struct stat statbuf;
+  if (!have_checked_for_dwp_) {
+    // Look for a .dwp file in the same directory as the executable.
+    have_checked_for_dwp_ = true;
+    string dwp_suffix(".dwp");
+    dwp_path_ = path_ + dwp_suffix;
+    if (stat(dwp_path_.c_str(), &statbuf) != 0) {
+      // Fall back to a split .debug file in the same directory.
+      string debug_suffix(".debug");
+      dwp_path_ = path_;
+      size_t found = path_.rfind(debug_suffix);
+      if (found + debug_suffix.length() == path_.length())
+        dwp_path_ = dwp_path_.replace(found, debug_suffix.length(), dwp_suffix);
+    }
+    if (stat(dwp_path_.c_str(), &statbuf) == 0) {
+      ElfReader* elf = new ElfReader(dwp_path_);
+      int width = GetElfWidth(*elf);
+      if (width != 0) {
+        dwp_byte_reader_.reset(new ByteReader(reader_->GetEndianness()));
+        dwp_byte_reader_->SetAddressSize(width);
+        dwp_reader_.reset(new DwpReader(*dwp_byte_reader_, elf));
+        dwp_reader_->Initialize();
+      } else {
+        delete elf;
+      }
+    }
+  }
+  bool found_in_dwp = false;
+  if (dwp_reader_ != NULL) {
+    // If we have a .dwp file, read the debug sections for the requested CU.
+    SectionMap sections;
+    dwp_reader_->ReadDebugSectionsForCU(dwo_id_, &sections);
+    if (!sections.empty()) {
+      found_in_dwp = true;
+      CompilationUnit dwp_comp_unit(dwp_path_, sections, 0,
+                                    dwp_byte_reader_.get(), handler_);
+      dwp_comp_unit.SetSplitDwarf(addr_buffer_, addr_buffer_length_, addr_base_,
+                                  ranges_base_, dwo_id_);
+      dwp_comp_unit.Start();
+    }
+  }
+  if (!found_in_dwp) {
+    // If no .dwp file, try to open the .dwo file.
+    if (stat(dwo_name_, &statbuf) == 0) {
+      ElfReader elf(dwo_name_);
+      int width = GetElfWidth(elf);
+      if (width != 0) {
+        ByteReader reader(ENDIANNESS_LITTLE);
+        reader.SetAddressSize(width);
+        SectionMap sections;
+        ReadDebugSectionsFromDwo(&elf, &sections);
+        CompilationUnit dwo_comp_unit(dwo_name_, sections, 0, &reader,
+                                      handler_);
+        dwo_comp_unit.SetSplitDwarf(addr_buffer_, addr_buffer_length_,
+                                    addr_base_, ranges_base_, dwo_id_);
+        dwo_comp_unit.Start();
+      }
+    }
+  }
+}
+
+void CompilationUnit::ReadDebugSectionsFromDwo(ElfReader* elf_reader,
+                                               SectionMap* sections) {
+  static const char* const section_names[] = {
+    ".debug_abbrev",
+    ".debug_info",
+    ".debug_str_offsets",
+    ".debug_str"
+  };
+  for (unsigned int i = 0u;
+       i < sizeof(section_names)/sizeof(*(section_names)); ++i) {
+    string base_name = section_names[i];
+    string dwo_name = base_name + ".dwo";
+    size_t section_size;
+    const char* section_data = elf_reader->GetSectionByName(dwo_name,
+                                                            &section_size);
+    if (section_data != NULL)
+      sections->insert(std::make_pair(
+          base_name, std::make_pair(
+             reinterpret_cast<const uint8_t *>(section_data),
+             section_size)));
+  }
+}
+
+DwpReader::DwpReader(const ByteReader& byte_reader, ElfReader* elf_reader)
+    : elf_reader_(elf_reader), byte_reader_(byte_reader),
+      cu_index_(NULL), cu_index_size_(0), string_buffer_(NULL),
+      string_buffer_size_(0), version_(0), ncolumns_(0), nunits_(0),
+      nslots_(0), phash_(NULL), pindex_(NULL), shndx_pool_(NULL),
+      offset_table_(NULL), size_table_(NULL), abbrev_data_(NULL),
+      abbrev_size_(0), info_data_(NULL), info_size_(0),
+      str_offsets_data_(NULL), str_offsets_size_(0) {}
+
+DwpReader::~DwpReader() {
+  if (elf_reader_) delete elf_reader_;
+}
+
+void DwpReader::Initialize() {
+  cu_index_ = elf_reader_->GetSectionByName(".debug_cu_index",
+                                            &cu_index_size_);
+  if (cu_index_ == NULL) {
+    return;
+  }
+  // The .debug_str.dwo section is shared by all CUs in the file.
+  string_buffer_ = elf_reader_->GetSectionByName(".debug_str.dwo",
+                                                 &string_buffer_size_);
+
+  version_ = byte_reader_.ReadFourBytes(
+      reinterpret_cast<const uint8_t *>(cu_index_));
+
+  if (version_ == 1) {
+    nslots_ = byte_reader_.ReadFourBytes(
+        reinterpret_cast<const uint8_t *>(cu_index_)
+        + 3 * sizeof(uint32));
+    phash_ = cu_index_ + 4 * sizeof(uint32);
+    pindex_ = phash_ + nslots_ * sizeof(uint64);
+    shndx_pool_ = pindex_ + nslots_ * sizeof(uint32);
+    if (shndx_pool_ >= cu_index_ + cu_index_size_) {
+      version_ = 0;
+    }
+  } else if (version_ == 2) {
+    ncolumns_ = byte_reader_.ReadFourBytes(
+        reinterpret_cast<const uint8_t *>(cu_index_) + sizeof(uint32));
+    nunits_ = byte_reader_.ReadFourBytes(
+        reinterpret_cast<const uint8_t *>(cu_index_) + 2 * sizeof(uint32));
+    nslots_ = byte_reader_.ReadFourBytes(
+        reinterpret_cast<const uint8_t *>(cu_index_) + 3 * sizeof(uint32));
+    phash_ = cu_index_ + 4 * sizeof(uint32);
+    pindex_ = phash_ + nslots_ * sizeof(uint64);
+    offset_table_ = pindex_ + nslots_ * sizeof(uint32);
+    size_table_ = offset_table_ + ncolumns_ * (nunits_ + 1) * sizeof(uint32);
+    abbrev_data_ = elf_reader_->GetSectionByName(".debug_abbrev.dwo",
+                                                 &abbrev_size_);
+    info_data_ = elf_reader_->GetSectionByName(".debug_info.dwo", &info_size_);
+    str_offsets_data_ = elf_reader_->GetSectionByName(".debug_str_offsets.dwo",
+                                                      &str_offsets_size_);
+    if (size_table_ >= cu_index_ + cu_index_size_) {
+      version_ = 0;
+    }
+  }
+}
+
+void DwpReader::ReadDebugSectionsForCU(uint64 dwo_id,
+                                       SectionMap* sections) {
+  if (version_ == 1) {
+    int slot = LookupCU(dwo_id);
+    if (slot == -1) {
+      return;
+    }
+
+    // The index table points to the section index pool, where we
+    // can read a list of section indexes for the debug sections
+    // for the CU whose dwo_id we are looking for.
+    int index = byte_reader_.ReadFourBytes(
+        reinterpret_cast<const uint8_t *>(pindex_)
+        + slot * sizeof(uint32));
+    const char* shndx_list = shndx_pool_ + index * sizeof(uint32);
+    for (;;) {
+      if (shndx_list >= cu_index_ + cu_index_size_) {
+        version_ = 0;
+        return;
+      }
+      unsigned int shndx = byte_reader_.ReadFourBytes(
+          reinterpret_cast<const uint8_t *>(shndx_list));
+      shndx_list += sizeof(uint32);
+      if (shndx == 0)
+        break;
+      const char* section_name = elf_reader_->GetSectionName(shndx);
+      size_t section_size;
+      const char* section_data;
+      // We're only interested in these four debug sections.
+      // The section names in the .dwo file end with ".dwo", but we
+      // add them to the sections table with their normal names.
+      if (!strncmp(section_name, ".debug_abbrev", strlen(".debug_abbrev"))) {
+        section_data = elf_reader_->GetSectionByIndex(shndx, &section_size);
+        sections->insert(std::make_pair(
+            ".debug_abbrev",
+            std::make_pair(reinterpret_cast<const uint8_t *> (section_data),
+                                                              section_size)));
+      } else if (!strncmp(section_name, ".debug_info", strlen(".debug_info"))) {
+        section_data = elf_reader_->GetSectionByIndex(shndx, &section_size);
+        sections->insert(std::make_pair(
+            ".debug_info",
+            std::make_pair(reinterpret_cast<const uint8_t *> (section_data),
+                           section_size)));
+      } else if (!strncmp(section_name, ".debug_str_offsets",
+                          strlen(".debug_str_offsets"))) {
+        section_data = elf_reader_->GetSectionByIndex(shndx, &section_size);
+        sections->insert(std::make_pair(
+            ".debug_str_offsets",
+            std::make_pair(reinterpret_cast<const uint8_t *> (section_data),
+                           section_size)));
+      }
+    }
+    sections->insert(std::make_pair(
+        ".debug_str",
+        std::make_pair(reinterpret_cast<const uint8_t *> (string_buffer_),
+                       string_buffer_size_)));
+  } else if (version_ == 2) {
+    uint32 index = LookupCUv2(dwo_id);
+    if (index == 0) {
+      return;
+    }
+
+    // The index points to a row in each of the section offsets table
+    // and the section size table, where we can read the offsets and sizes
+    // of the contributions to each debug section from the CU whose dwo_id
+    // we are looking for. Row 0 of the section offsets table has the
+    // section ids for each column of the table. The size table begins
+    // with row 1.
+    const char* id_row = offset_table_;
+    const char* offset_row = offset_table_
+                             + index * ncolumns_ * sizeof(uint32);
+    const char* size_row =
+        size_table_ + (index - 1) * ncolumns_ * sizeof(uint32);
+    if (size_row + ncolumns_ * sizeof(uint32) > cu_index_ + cu_index_size_) {
+      version_ = 0;
+      return;
+    }
+    for (unsigned int col = 0u; col < ncolumns_; ++col) {
+      uint32 section_id =
+          byte_reader_.ReadFourBytes(reinterpret_cast<const uint8_t *>(id_row)
+                                     + col * sizeof(uint32));
+      uint32 offset = byte_reader_.ReadFourBytes(
+          reinterpret_cast<const uint8_t *>(offset_row)
+          + col * sizeof(uint32));
+      uint32 size = byte_reader_.ReadFourBytes(
+          reinterpret_cast<const uint8_t *>(size_row) + col * sizeof(uint32));
+      if (section_id == DW_SECT_ABBREV) {
+        sections->insert(std::make_pair(
+            ".debug_abbrev",
+            std::make_pair(reinterpret_cast<const uint8_t *> (abbrev_data_)
+                           + offset, size)));
+      } else if (section_id == DW_SECT_INFO) {
+        sections->insert(std::make_pair(
+            ".debug_info",
+            std::make_pair(reinterpret_cast<const uint8_t *> (info_data_)
+                           + offset, size)));
+      } else if (section_id == DW_SECT_STR_OFFSETS) {
+        sections->insert(std::make_pair(
+            ".debug_str_offsets",
+            std::make_pair(reinterpret_cast<const uint8_t *> (str_offsets_data_)
+                           + offset, size)));
+      }
+    }
+    sections->insert(std::make_pair(
+        ".debug_str",
+        std::make_pair(reinterpret_cast<const uint8_t *> (string_buffer_),
+                       string_buffer_size_)));
+  }
+}
+
+int DwpReader::LookupCU(uint64 dwo_id) {
+  uint32 slot = static_cast<uint32>(dwo_id) & (nslots_ - 1);
+  uint64 probe = byte_reader_.ReadEightBytes(
+      reinterpret_cast<const uint8_t *>(phash_) + slot * sizeof(uint64));
+  if (probe != 0 && probe != dwo_id) {
+    uint32 secondary_hash =
+        (static_cast<uint32>(dwo_id >> 32) & (nslots_ - 1)) | 1;
+    do {
+      slot = (slot + secondary_hash) & (nslots_ - 1);
+      probe = byte_reader_.ReadEightBytes(
+          reinterpret_cast<const uint8_t *>(phash_) + slot * sizeof(uint64));
+    } while (probe != 0 && probe != dwo_id);
+  }
+  if (probe == 0)
+    return -1;
+  return slot;
+}
+
+uint32 DwpReader::LookupCUv2(uint64 dwo_id) {
+  uint32 slot = static_cast<uint32>(dwo_id) & (nslots_ - 1);
+  uint64 probe = byte_reader_.ReadEightBytes(
+      reinterpret_cast<const uint8_t *>(phash_) + slot * sizeof(uint64));
+  uint32 index = byte_reader_.ReadFourBytes(
+      reinterpret_cast<const uint8_t *>(pindex_) + slot * sizeof(uint32));
+  if (index != 0 && probe != dwo_id) {
+    uint32 secondary_hash =
+        (static_cast<uint32>(dwo_id >> 32) & (nslots_ - 1)) | 1;
+    do {
+      slot = (slot + secondary_hash) & (nslots_ - 1);
+      probe = byte_reader_.ReadEightBytes(
+          reinterpret_cast<const uint8_t *>(phash_) + slot * sizeof(uint64));
+      index = byte_reader_.ReadFourBytes(
+          reinterpret_cast<const uint8_t *>(pindex_) + slot * sizeof(uint32));
+    } while (index != 0 && probe != dwo_id);
+  }
+  return index;
+}
+
 LineInfo::LineInfo(const uint8_t *buffer, uint64 buffer_length,
                    ByteReader* reader, LineInfoHandler* handler):
     handler_(handler), reader_(reader), buffer_(buffer) {

src/common/dwarf/dwarf2reader.h

@@ -47,16 +47,19 @@
 #include <string>
 #include <utility>
 #include <vector>
+#include <memory>
 
 #include "common/dwarf/bytereader.h"
 #include "common/dwarf/dwarf2enums.h"
 #include "common/dwarf/types.h"
 #include "common/using_std_string.h"
+#include "common/dwarf/elf_reader.h"
 
 namespace dwarf2reader {
 struct LineStateMachine;
 class Dwarf2Handler;
 class LineInfoHandler;
+class DwpReader;
 
 // This maps from a string naming a section to a pair containing a
 // the data for the section, and the size of the section.
@@ -184,151 +187,10 @@ class LineInfoHandler {
                        uint32 file_num, uint32 line_num, uint32 column_num) { }
 };
 
-// The base of DWARF2/3 debug info is a DIE (Debugging Information
-// Entry.
-// DWARF groups DIE's into a tree and calls the root of this tree a
-// "compilation unit".  Most of the time, there is one compilation
-// unit in the .debug_info section for each file that had debug info
-// generated.
-// Each DIE consists of
-
-// 1. a tag specifying a thing that is being described (ie
-// DW_TAG_subprogram for functions, DW_TAG_variable for variables, etc
-// 2. attributes (such as DW_AT_location for location in memory,
-// DW_AT_name for name), and data for each attribute.
-// 3. A flag saying whether the DIE has children or not
-
-// In order to gain some amount of compression, the format of
-// each DIE (tag name, attributes and data forms for the attributes)
-// are stored in a separate table called the "abbreviation table".
-// This is done because a large number of DIEs have the exact same tag
-// and list of attributes, but different data for those attributes.
-// As a result, the .debug_info section is just a stream of data, and
-// requires reading of the .debug_abbrev section to say what the data
-// means.
-
-// As a warning to the user, it should be noted that the reason for
-// using absolute offsets from the beginning of .debug_info is that
-// DWARF2/3 supports referencing DIE's from other DIE's by their offset
-// from either the current compilation unit start, *or* the beginning
-// of the .debug_info section.  This means it is possible to reference
-// a DIE in one compilation unit from a DIE in another compilation
-// unit.  This style of reference is usually used to eliminate
-// duplicated information that occurs across compilation
-// units, such as base types, etc.  GCC 3.4+ support this with
-// -feliminate-dwarf2-dups.  Other toolchains will sometimes do
-// duplicate elimination in the linker.
-
-class CompilationUnit {
- public:
-
-  // Initialize a compilation unit.  This requires a map of sections,
-  // the offset of this compilation unit in the .debug_info section, a
-  // ByteReader, and a Dwarf2Handler class to call callbacks in.
-  CompilationUnit(const SectionMap& sections, uint64 offset,
-                  ByteReader* reader, Dwarf2Handler* handler);
-  virtual ~CompilationUnit() {
-    if (abbrevs_) delete abbrevs_;
-  }
-
-  // Begin reading a Dwarf2 compilation unit, and calling the
-  // callbacks in the Dwarf2Handler
-
-  // Return the full length of the compilation unit, including
-  // headers. This plus the starting offset passed to the constructor
-  // is the offset of the end of the compilation unit --- and the
-  // start of the next compilation unit, if there is one.
-  uint64 Start();
-
- private:
-
-  // This struct represents a single DWARF2/3 abbreviation
-  // The abbreviation tells how to read a DWARF2/3 DIE, and consist of a
-  // tag and a list of attributes, as well as the data form of each attribute.
-  struct Abbrev {
-    uint64 number;
-    enum DwarfTag tag;
-    bool has_children;
-    AttributeList attributes;
-  };
-
-  // A DWARF2/3 compilation unit header.  This is not the same size as
-  // in the actual file, as the one in the file may have a 32 bit or
-  // 64 bit length.
-  struct CompilationUnitHeader {
-    uint64 length;
-    uint16 version;
-    uint64 abbrev_offset;
-    uint8 address_size;
-  } header_;
-
-  // Reads the DWARF2/3 header for this compilation unit.
-  void ReadHeader();
-
-  // Reads the DWARF2/3 abbreviations for this compilation unit
-  void ReadAbbrevs();
-
-  // Processes a single DIE for this compilation unit and return a new
-  // pointer just past the end of it
-  const uint8_t *ProcessDIE(uint64 dieoffset,
-                            const uint8_t *start,
-                            const Abbrev& abbrev);
-
-  // Processes a single attribute and return a new pointer just past the
-  // end of it
-  const uint8_t *ProcessAttribute(uint64 dieoffset,
-                                  const uint8_t *start,
-                                  enum DwarfAttribute attr,
-                                  enum DwarfForm form);
-
-  // Processes all DIEs for this compilation unit
-  void ProcessDIEs();
-
-  // Skips the die with attributes specified in ABBREV starting at
-  // START, and return the new place to position the stream to.
-  const uint8_t *SkipDIE(const uint8_t *start, const Abbrev& abbrev);
-
-  // Skips the attribute starting at START, with FORM, and return the
-  // new place to position the stream to.
-  const uint8_t *SkipAttribute(const uint8_t *start, enum DwarfForm form);
-
-  // Offset from section start is the offset of this compilation unit
-  // from the beginning of the .debug_info section.
-  uint64 offset_from_section_start_;
-
-  // buffer is the buffer for our CU, starting at .debug_info + offset
-  // passed in from constructor.
-  // after_header points to right after the compilation unit header.
-  const uint8_t *buffer_;
-  uint64 buffer_length_;
-  const uint8_t *after_header_;
-
-  // The associated ByteReader that handles endianness issues for us
-  ByteReader* reader_;
-
-  // The map of sections in our file to buffers containing their data
-  const SectionMap& sections_;
-
-  // The associated handler to call processing functions in
-  Dwarf2Handler* handler_;
-
-  // Set of DWARF2/3 abbreviations for this compilation unit.  Indexed
-  // by abbreviation number, which means that abbrevs_[0] is not
-  // valid.
-  std::vector<Abbrev>* abbrevs_;
-
-  // String section buffer and length, if we have a string section.
-  // This is here to avoid doing a section lookup for strings in
-  // ProcessAttribute, which is in the hot path for DWARF2 reading.
-  const uint8_t *string_buffer_;
-  uint64 string_buffer_length_;
-};
-
 // This class is the main interface between the reader and the
 // client.  The virtual functions inside this get called for
 // interesting events that happen during DWARF2 reading.
 // The default implementation skips everything.
-
 class Dwarf2Handler {
  public:
   Dwarf2Handler() { }
@@ -342,6 +204,19 @@ class Dwarf2Handler {
                                     uint8 offset_size, uint64 cu_length,
                                     uint8 dwarf_version) { return false; }
 
+  // When processing a skeleton compilation unit, resulting from a split
+  // DWARF compilation, once the skeleton debug info has been read,
+  // the reader will call this function to ask the client if it needs
+  // the full debug info from the .dwo or .dwp file.  Return true if
+  // you need it, or false to skip processing the split debug info.
+  virtual bool NeedSplitDebugInfo() { return true; }
+
+  // Start to process a split compilation unit at OFFSET from the beginning of
+  // the debug_info section in the .dwp/.dwo file.  Return false if you would
+  // like to skip this compilation unit.
+  virtual bool StartSplitCompilationUnit(uint64 offset,
+                                         uint64 cu_length) { return false; }
+
   // Start to process a DIE at OFFSET from the beginning of the .debug_info
   // section. Return false if you would like to skip this DIE.
   virtual bool StartDIE(uint64 offset, enum DwarfTag tag) { return false; }
@@ -412,6 +287,367 @@ class Dwarf2Handler {
 
 };
 
+// The base of DWARF2/3 debug info is a DIE (Debugging Information
+// Entry.
+// DWARF groups DIE's into a tree and calls the root of this tree a
+// "compilation unit".  Most of the time, there is one compilation
+// unit in the .debug_info section for each file that had debug info
+// generated.
+// Each DIE consists of
+
+// 1. a tag specifying a thing that is being described (ie
+// DW_TAG_subprogram for functions, DW_TAG_variable for variables, etc
+// 2. attributes (such as DW_AT_location for location in memory,
+// DW_AT_name for name), and data for each attribute.
+// 3. A flag saying whether the DIE has children or not
+
+// In order to gain some amount of compression, the format of
+// each DIE (tag name, attributes and data forms for the attributes)
+// are stored in a separate table called the "abbreviation table".
+// This is done because a large number of DIEs have the exact same tag
+// and list of attributes, but different data for those attributes.
+// As a result, the .debug_info section is just a stream of data, and
+// requires reading of the .debug_abbrev section to say what the data
+// means.
+
+// As a warning to the user, it should be noted that the reason for
+// using absolute offsets from the beginning of .debug_info is that
+// DWARF2/3 supports referencing DIE's from other DIE's by their offset
+// from either the current compilation unit start, *or* the beginning
+// of the .debug_info section.  This means it is possible to reference
+// a DIE in one compilation unit from a DIE in another compilation
+// unit.  This style of reference is usually used to eliminate
+// duplicated information that occurs across compilation
+// units, such as base types, etc.  GCC 3.4+ support this with
+// -feliminate-dwarf2-dups.  Other toolchains will sometimes do
+// duplicate elimination in the linker.
+
+class CompilationUnit {
+ public:
+
+  // Initialize a compilation unit.  This requires a map of sections,
+  // the offset of this compilation unit in the .debug_info section, a
+  // ByteReader, and a Dwarf2Handler class to call callbacks in.
+  CompilationUnit(const string& path, const SectionMap& sections, uint64 offset,
+                  ByteReader* reader, Dwarf2Handler* handler);
+  virtual ~CompilationUnit() {
+    if (abbrevs_) delete abbrevs_;
+  }
+
+  // Initialize a compilation unit from a .dwo or .dwp file.
+  // In this case, we need the .debug_addr section from the
+  // executable file that contains the corresponding skeleton
+  // compilation unit.  We also inherit the Dwarf2Handler from
+  // the executable file, and call it as if we were still
+  // processing the original compilation unit.
+  void SetSplitDwarf(const uint8_t* addr_buffer, uint64 addr_buffer_length,
+                     uint64 addr_base, uint64 ranges_base, uint64 dwo_id);
+
+  // Begin reading a Dwarf2 compilation unit, and calling the
+  // callbacks in the Dwarf2Handler
+
+  // Return the full length of the compilation unit, including
+  // headers. This plus the starting offset passed to the constructor
+  // is the offset of the end of the compilation unit --- and the
+  // start of the next compilation unit, if there is one.
+  uint64 Start();
+
+ private:
+
+  // This struct represents a single DWARF2/3 abbreviation
+  // The abbreviation tells how to read a DWARF2/3 DIE, and consist of a
+  // tag and a list of attributes, as well as the data form of each attribute.
+  struct Abbrev {
+    uint64 number;
+    enum DwarfTag tag;
+    bool has_children;
+    AttributeList attributes;
+  };
+
+  // A DWARF2/3 compilation unit header.  This is not the same size as
+  // in the actual file, as the one in the file may have a 32 bit or
+  // 64 bit length.
+  struct CompilationUnitHeader {
+    uint64 length;
+    uint16 version;
+    uint64 abbrev_offset;
+    uint8 address_size;
+  } header_;
+
+  // Reads the DWARF2/3 header for this compilation unit.
+  void ReadHeader();
+
+  // Reads the DWARF2/3 abbreviations for this compilation unit
+  void ReadAbbrevs();
+
+  // Processes a single DIE for this compilation unit and return a new
+  // pointer just past the end of it
+  const uint8_t *ProcessDIE(uint64 dieoffset,
+                            const uint8_t *start,
+                            const Abbrev& abbrev);
+
+  // Processes a single attribute and return a new pointer just past the
+  // end of it
+  const uint8_t *ProcessAttribute(uint64 dieoffset,
+                                  const uint8_t *start,
+                                  enum DwarfAttribute attr,
+                                  enum DwarfForm form);
+
+  // Called when we have an attribute with unsigned data to give to
+  // our handler.  The attribute is for the DIE at OFFSET from the
+  // beginning of compilation unit, has a name of ATTR, a form of
+  // FORM, and the actual data of the attribute is in DATA.
+  // If we see a DW_AT_GNU_dwo_id attribute, save the value so that
+  // we can find the debug info in a .dwo or .dwp file.
+  void ProcessAttributeUnsigned(uint64 offset,
+                                enum DwarfAttribute attr,
+                                enum DwarfForm form,
+                                uint64 data) {
+    if (attr == DW_AT_GNU_dwo_id) {
+      dwo_id_ = data;
+    }
+    else if (attr == DW_AT_GNU_addr_base) {
+      addr_base_ = data;
+    }
+    else if (attr == DW_AT_GNU_ranges_base) {
+      ranges_base_ = data;
+    }
+    // TODO(yunlian): When we add DW_AT_ranges_base from DWARF-5,
+    // that base will apply to DW_AT_ranges attributes in the
+    // skeleton CU as well as in the .dwo/.dwp files.
+    else if (attr == DW_AT_ranges && is_split_dwarf_) {
+      data += ranges_base_;
+    }
+    handler_->ProcessAttributeUnsigned(offset, attr, form, data);
+  }
+
+  // Called when we have an attribute with signed data to give to
+  // our handler.  The attribute is for the DIE at OFFSET from the
+  // beginning of compilation unit, has a name of ATTR, a form of
+  // FORM, and the actual data of the attribute is in DATA.
+  void ProcessAttributeSigned(uint64 offset,
+                              enum DwarfAttribute attr,
+                              enum DwarfForm form,
+                              int64 data) {
+    handler_->ProcessAttributeSigned(offset, attr, form, data);
+  }
+
+  // Called when we have an attribute with a buffer of data to give to
+  // our handler.  The attribute is for the DIE at OFFSET from the
+  // beginning of compilation unit, has a name of ATTR, a form of
+  // FORM, and the actual data of the attribute is in DATA, and the
+  // length of the buffer is LENGTH.
+  void ProcessAttributeBuffer(uint64 offset,
+                              enum DwarfAttribute attr,
+                              enum DwarfForm form,
+                              const uint8_t* data,
+                              uint64 len) {
+    handler_->ProcessAttributeBuffer(offset, attr, form, data, len);
+  }
+
+  // Called when we have an attribute with string data to give to
+  // our handler.  The attribute is for the DIE at OFFSET from the
+  // beginning of compilation unit, has a name of ATTR, a form of
+  // FORM, and the actual data of the attribute is in DATA.
+  // If we see a DW_AT_GNU_dwo_name attribute, save the value so
+  // that we can find the debug info in a .dwo or .dwp file.
+  void ProcessAttributeString(uint64 offset,
+                              enum DwarfAttribute attr,
+                              enum DwarfForm form,
+                              const char* data) {
+    if (attr == DW_AT_GNU_dwo_name)
+      dwo_name_ = data;
+    handler_->ProcessAttributeString(offset, attr, form, data);
+  }
+
+  // Processes all DIEs for this compilation unit
+  void ProcessDIEs();
+
+  // Skips the die with attributes specified in ABBREV starting at
+  // START, and return the new place to position the stream to.
+  const uint8_t *SkipDIE(const uint8_t *start, const Abbrev& abbrev);
+
+  // Skips the attribute starting at START, with FORM, and return the
+  // new place to position the stream to.
+  const uint8_t *SkipAttribute(const uint8_t *start, enum DwarfForm form);
+
+  // Process the actual debug information in a split DWARF file.
+  void ProcessSplitDwarf();
+
+  // Read the debug sections from a .dwo file.
+  void ReadDebugSectionsFromDwo(ElfReader* elf_reader,
+                                SectionMap* sections);
+
+  // Path of the file containing the debug information.
+  const string path_;
+
+  // Offset from section start is the offset of this compilation unit
+  // from the beginning of the .debug_info section.
+  uint64 offset_from_section_start_;
+
+  // buffer is the buffer for our CU, starting at .debug_info + offset
+  // passed in from constructor.
+  // after_header points to right after the compilation unit header.
+  const uint8_t *buffer_;
+  uint64 buffer_length_;
+  const uint8_t *after_header_;
+
+  // The associated ByteReader that handles endianness issues for us
+  ByteReader* reader_;
+
+  // The map of sections in our file to buffers containing their data
+  const SectionMap& sections_;
+
+  // The associated handler to call processing functions in
+  Dwarf2Handler* handler_;
+
+  // Set of DWARF2/3 abbreviations for this compilation unit.  Indexed
+  // by abbreviation number, which means that abbrevs_[0] is not
+  // valid.
+  std::vector<Abbrev>* abbrevs_;
+
+  // String section buffer and length, if we have a string section.
+  // This is here to avoid doing a section lookup for strings in
+  // ProcessAttribute, which is in the hot path for DWARF2 reading.
+  const uint8_t *string_buffer_;
+  uint64 string_buffer_length_;
+
+  // String offsets section buffer and length, if we have a string offsets
+  // section (.debug_str_offsets or .debug_str_offsets.dwo).
+  const uint8_t* str_offsets_buffer_;
+  uint64 str_offsets_buffer_length_;
+
+  // Address section buffer and length, if we have an address section
+  // (.debug_addr).
+  const uint8_t* addr_buffer_;
+  uint64 addr_buffer_length_;
+
+  // Flag indicating whether this compilation unit is part of a .dwo
+  // or .dwp file.  If true, we are reading this unit because a
+  // skeleton compilation unit in an executable file had a
+  // DW_AT_GNU_dwo_name or DW_AT_GNU_dwo_id attribute.
+  // In a .dwo file, we expect the string offsets section to
+  // have a ".dwo" suffix, and we will use the ".debug_addr" section
+  // associated with the skeleton compilation unit.
+  bool is_split_dwarf_;
+
+  // The value of the DW_AT_GNU_dwo_id attribute, if any.
+  uint64 dwo_id_;
+
+  // The value of the DW_AT_GNU_dwo_name attribute, if any.
+  const char* dwo_name_;
+
+  // If this is a split DWARF CU, the value of the DW_AT_GNU_dwo_id attribute
+  // from the skeleton CU.
+  uint64 skeleton_dwo_id_;
+
+  // The value of the DW_AT_GNU_ranges_base attribute, if any.
+  uint64 ranges_base_;
+
+  // The value of the DW_AT_GNU_addr_base attribute, if any.
+  uint64 addr_base_;
+
+  // True if we have already looked for a .dwp file.
+  bool have_checked_for_dwp_;
+
+  // Path to the .dwp file.
+  string dwp_path_;
+
+  // ByteReader for the DWP file.
+  std::unique_ptr<ByteReader> dwp_byte_reader_;
+
+  // DWP reader.
+   std::unique_ptr<DwpReader> dwp_reader_;
+};
+
+// A Reader for a .dwp file.  Supports the fetching of DWARF debug
+// info for a given dwo_id.
+//
+// There are two versions of .dwp files.  In both versions, the
+// .dwp file is an ELF file containing only debug sections.
+// In Version 1, the file contains many copies of each debug
+// section, one for each .dwo file that is packaged in the .dwp
+// file, and the .debug_cu_index section maps from the dwo_id
+// to a set of section indexes.  In Version 2, the file contains
+// one of each debug section, and the .debug_cu_index section
+// maps from the dwo_id to a set of offsets and lengths that
+// identify each .dwo file's contribution to the larger sections.
+
+class DwpReader {
+ public:
+  DwpReader(const ByteReader& byte_reader, ElfReader* elf_reader);
+
+  ~DwpReader();
+
+  // Read the CU index and initialize data members.
+  void Initialize();
+
+  // Read the debug sections for the given dwo_id.
+  void ReadDebugSectionsForCU(uint64 dwo_id, SectionMap* sections);
+
+ private:
+  // Search a v1 hash table for "dwo_id".  Returns the slot index
+  // where the dwo_id was found, or -1 if it was not found.
+  int LookupCU(uint64 dwo_id);
+
+  // Search a v2 hash table for "dwo_id".  Returns the row index
+  // in the offsets and sizes tables, or 0 if it was not found.
+  uint32 LookupCUv2(uint64 dwo_id);
+
+  // The ELF reader for the .dwp file.
+  ElfReader* elf_reader_;
+
+  // The ByteReader for the .dwp file.
+  const ByteReader& byte_reader_;
+
+  // Pointer to the .debug_cu_index section.
+  const char* cu_index_;
+
+  // Size of the .debug_cu_index section.
+  size_t cu_index_size_;
+
+  // Pointer to the .debug_str.dwo section.
+  const char* string_buffer_;
+
+  // Size of the .debug_str.dwo section.
+  size_t string_buffer_size_;
+
+  // Version of the .dwp file.  We support versions 1 and 2 currently.
+  int version_;
+
+  // Number of columns in the section tables (version 2).
+  unsigned int ncolumns_;
+
+  // Number of units in the section tables (version 2).
+  unsigned int nunits_;
+
+  // Number of slots in the hash table.
+  unsigned int nslots_;
+
+  // Pointer to the beginning of the hash table.
+  const char* phash_;
+
+  // Pointer to the beginning of the index table.
+  const char* pindex_;
+
+  // Pointer to the beginning of the section index pool (version 1).
+  const char* shndx_pool_;
+
+  // Pointer to the beginning of the section offset table (version 2).
+  const char* offset_table_;
+
+  // Pointer to the beginning of the section size table (version 2).
+  const char* size_table_;
+
+  // Contents of the sections of interest (version 2).
+  const char* abbrev_data_;
+  size_t abbrev_size_;
+  const char* info_data_;
+  size_t info_size_;
+  const char* str_offsets_data_;
+  size_t str_offsets_size_;
+};
+
 // This class is a reader for DWARF's Call Frame Information.  CFI
 // describes how to unwind stack frames --- even for functions that do
 // not follow fixed conventions for saving registers, whose frame size

src/common/dwarf/elf_reader.h

@@ -0,0 +1,166 @@
+// Copyright 2005 Google Inc. All Rights Reserved.
+// Author: chatham@google.com (Andrew Chatham)
+// Author: satorux@google.com (Satoru Takabayashi)
+//
+// ElfReader handles reading in ELF. It can extract symbols from the
+// current process, which may be used to symbolize stack traces
+// without having to make a potentially dangerous call to fork().
+//
+// ElfReader dynamically allocates memory, so it is not appropriate to
+// use once the address space might be corrupted, such as during
+// process death.
+//
+// ElfReader supports both 32-bit and 64-bit ELF binaries.
+
+#ifndef COMMON_DWARF_ELF_READER_H__
+#define COMMON_DWARF_ELF_READER_H__
+
+#include <string>
+#include <vector>
+
+#include "common/dwarf/types.h"
+
+using std::string;
+using std::vector;
+using std::pair;
+
+namespace dwarf2reader {
+
+class SymbolMap;
+class Elf32;
+class Elf64;
+template<typename ElfArch>
+class ElfReaderImpl;
+
+class ElfReader {
+ public:
+  explicit ElfReader(const string &path);
+  ~ElfReader();
+
+  // Parse the ELF prologue of this file and return whether it was
+  // successfully parsed and matches the word size and byte order of
+  // the current process.
+  bool IsNativeElfFile() const;
+
+  // Similar to IsNativeElfFile but checks if it's a 32-bit ELF file.
+  bool IsElf32File() const;
+
+  // Similar to IsNativeElfFile but checks if it's a 64-bit ELF file.
+  bool IsElf64File() const;
+
+  // Checks if it's an ELF file of type ET_DYN (shared object file).
+  bool IsDynamicSharedObject();
+
+  // Add symbols in the given ELF file into the provided SymbolMap,
+  // assuming that the file has been loaded into the specified
+  // offset.
+  //
+  // The remaining arguments are typically taken from a
+  // ProcMapsIterator (base/sysinfo.h) and describe which portions of
+  // the ELF file are mapped into which parts of memory:
+  //
+  // mem_offset - position at which the segment is mapped into memory
+  // file_offset - offset in the file where the mapping begins
+  // length - length of the mapped segment
+  void AddSymbols(SymbolMap *symbols,
+                  uint64 mem_offset, uint64 file_offset,
+                  uint64 length);
+
+  class SymbolSink {
+   public:
+    virtual ~SymbolSink() {}
+    virtual void AddSymbol(const char *name, uint64 address, uint64 size) = 0;
+  };
+
+  // Like AddSymbols above, but with no address correction.
+  // Processes any SHT_SYMTAB section, followed by any SHT_DYNSYM section.
+  void VisitSymbols(SymbolSink *sink);
+
+  // Like VisitSymbols above, but for a specific symbol binding/type.
+  // A negative value for the binding and type parameters means any
+  // binding or type.
+  void VisitSymbols(SymbolSink *sink, int symbol_binding, int symbol_type);
+
+  // Like VisitSymbols above but can optionally export raw symbol values instead
+  // of adjusted ones.
+  void VisitSymbols(SymbolSink *sink, int symbol_binding, int symbol_type,
+                    bool get_raw_symbol_values);
+
+  // p_vaddr of the first PT_LOAD segment (if any), or 0 if no PT_LOAD
+  // segments are present. This is the address an ELF image was linked
+  // (by static linker) to be loaded at. Usually (but not always) 0 for
+  // shared libraries and position-independent executables.
+  uint64 VaddrOfFirstLoadSegment();
+
+  // Return the name of section "shndx".  Returns NULL if the section
+  // is not found.
+  const char *GetSectionName(int shndx);
+
+  // Return the number of sections in the given ELF file.
+  uint64 GetNumSections();
+
+  // Get section "shndx" from the given ELF file.  On success, return
+  // the pointer to the section and store the size in "size".
+  // On error, return NULL.  The returned section data is only valid
+  // until the ElfReader gets destroyed.
+  const char *GetSectionByIndex(int shndx, size_t *size);
+
+  // Get section with "section_name" (ex. ".text", ".symtab") in the
+  // given ELF file.  On success, return the pointer to the section
+  // and store the size in "size".  On error, return NULL.  The
+  // returned section data is only valid until the ElfReader gets
+  // destroyed.
+  const char *GetSectionByName(const string &section_name, size_t *size);
+
+  // This is like GetSectionByName() but it returns a lot of extra information
+  // about the section. The SectionInfo structure is almost identical to
+  // the typedef struct Elf64_Shdr defined in <elf.h>, but is redefined
+  // here so that the many short macro names in <elf.h> don't have to be
+  // added to our already cluttered namespace.
+  struct SectionInfo {
+    uint32 type;                // Section type (SHT_xxx constant from elf.h).
+    uint64 flags;               // Section flags (SHF_xxx constants from elf.h).
+    uint64 addr;                // Section virtual address at execution.
+    uint64 offset;              // Section file offset.
+    uint64 size;                // Section size in bytes.
+    uint32 link;                // Link to another section.
+    uint32 info;                // Additional section information.
+    uint64 addralign;           // Section alignment.
+    uint64 entsize;             // Entry size if section holds a table.
+  };
+  const char *GetSectionInfoByName(const string &section_name,
+                                   SectionInfo *info);
+
+  // Check if "path" is an ELF binary that has not been stripped of symbol
+  // tables.  This function supports both 32-bit and 64-bit ELF binaries.
+  static bool IsNonStrippedELFBinary(const string &path);
+
+  // Check if "path" is an ELF binary that has not been stripped of debug
+  // info. Unlike IsNonStrippedELFBinary, this function will return
+  // false for binaries passed through "strip -S".
+  static bool IsNonDebugStrippedELFBinary(const string &path);
+
+  // Match a requested section name with the section name as it
+  // appears in the elf-file, adjusting for compressed debug section
+  // names.  For example, returns true if name == ".debug_abbrev" and
+  // sh_name == ".zdebug_abbrev"
+  static bool SectionNamesMatch(const string &name, const string &sh_name);
+
+ private:
+  // Lazily initialize impl32_ and return it.
+  ElfReaderImpl<Elf32> *GetImpl32();
+  // Ditto for impl64_.
+  ElfReaderImpl<Elf64> *GetImpl64();
+
+  // Path of the file we're reading.
+  const string path_;
+  // Read-only file descriptor for the file. May be -1 if there was an
+  // error during open.
+  int fd_;
+  ElfReaderImpl<Elf32> *impl32_;
+  ElfReaderImpl<Elf64> *impl64_;
+};
+
+}  // namespace dwarf2reader
+
+#endif  // COMMON_DWARF_ELF_READER_H__

src/common/linux/dump_symbols.cc

@@ -288,7 +288,8 @@ bool LoadDwarf(const string& dwarf_filename,
     // Make a Dwarf2Handler that drives the DIEHandler.
     dwarf2reader::DIEDispatcher die_dispatcher(&root_handler);
     // Make a DWARF parser for the compilation unit at OFFSET.
-    dwarf2reader::CompilationUnit reader(file_context.section_map(),
+    dwarf2reader::CompilationUnit reader(dwarf_filename,
+                                         file_context.section_map(),
                                          offset,
                                          &byte_reader,
                                          &die_dispatcher);

src/common/mac/dump_syms.cc

@@ -437,7 +437,8 @@ bool DumpSymbols::ReadDwarf(google_breakpad::Module *module,
     // Make a Dwarf2Handler that drives our DIEHandler.
     dwarf2reader::DIEDispatcher die_dispatcher(&root_handler);
     // Make a DWARF parser for the compilation unit at OFFSET.
-    dwarf2reader::CompilationUnit dwarf_reader(file_context.section_map(),
+    dwarf2reader::CompilationUnit dwarf_reader(selected_object_name_,
+                                               file_context.section_map(),
                                                offset,
                                                &byte_reader,
                                                &die_dispatcher);