tree dd3b8018176ada85d51b2f8ca46e515fbf55b50f
parent 9dcf75c80187504ec88e7ef91d64a6a68279eb9d
author Yevgeny Rouban <yevgeny.y.rouban@intel.com> 1407490178 +0700
committer Tong Shen <endlessroad@google.com> 1408140252 -0700

ART source line debug info in OAT files

OAT files have source line information enough for ART runtime needs like
jump to/from interpreter and thread suspension. But this information
is not enough for finer grained source level debugging and low-level
profiling (VTune or perf).

This patch adds to OAT files two additional sections:
.debug_line - DWARF formatted Elf32 section with detailed source line
              information (mapping from native PC to Java source lines).

In addition to the debugging symbols added using the dex2oat option
--include-debug-symbols, the source line information is added to
the section .debug_line.

The source line info can be read by many Elf reading tools like objdump,
readelf, dwarfdump, gdb, perf, VTune, ...

gdb can use this debug line information in x86. In 64-bit mode
the information can be used if the oat file is mapped in the lower
address space (address has higher 32 bits zeroed). Relocation works.

Testing:
1. art/test/run-test --host --gdb [--64] 001-HelloWorld
2. in gdb: break Main.java:19
3. in gdb: break Runtime.java:111
4. in gdb: run  - stops at void java.lang.Runtime.<init>()
5. in gdb: backtrace  - shows call stack down to main()
6. in gdb: continue - stops at void Main.main() (only in 32-bit mode)
7. in gdb: backtrace  - shows call stack down to main()
8. objdump -W <oat-file> - addresses are from VMA range of .text
   section reported by objdump -h <file>
9. dwarfdump -ka <oat-file> - no errors expected

Size of aosp-x86-eng boot.oat increased by 11% from 80.5Mb to 89.2Mb
with two sections added .debug_line (7.2Mb) and .rel.debug (1.5Mb).

Change-Id: Ib8828832686e49782a63d5529008ff4814ed9cda
Signed-off-by: Yevgeny Rouban <yevgeny.y.rouban@intel.com>