Reviewers: Mads Ager,
Message:
Hi Mads,
This CL provides basic GDB JIT interface integration for the sake of V8
embedders who currently have to manually decode backtraces in gdb.
Here is an example of current backtrace:
-------------------------------------------
(gdb) bt
#0 Print (args=...) at samples/shell.cc:159
#1 0x0807eff9 in v8::internal::HandleApiCallHelper<false> (args=...) at
src/builtins.cc:1058
#2 0x0807c908 in v8::internal::Builtin_Impl_HandleApiCall (args=...) at
src/builtins.cc:1075
#3 0x0807c8ee in v8::internal::Builtin_HandleApiCall (args=...) at
src/builtins.cc:1074
#4 0xf5cae28e in ?? ()
#5 0xf5cc37a4 in ?? ()
#6 0xf5cafc1f in ?? ()
#7 0xf5cc3741 in ?? ()
#8 0xf5cc36df in ?? ()
#9 0xf5cc367b in ?? ()
#10 0xf5cbebd9 in ?? ()
#11 0xf5cb1e42 in ?? ()
-------------------------------------------
And here is an example of backtrace with gdbjit interface integration
enabled:
-------------------------------------------
(gdb) bt
#0 Print (args=...) at samples/shell.cc:159
#1 0x0807eff9 in v8::internal::HandleApiCallHelper<false> (args=...) at
src/builtins.cc:1058
#2 0x0807c908 in v8::internal::Builtin_Impl_HandleApiCall (args=...) at
src/builtins.cc:1075
#3 0x0807c8ee in v8::internal::Builtin_HandleApiCall (args=...) at
src/builtins.cc:1074
#4 0xf5cae28e in ?? ()
#5 0xf5cc4724 in baz () at test.js:10
#6 0xf5cafc1f in ?? ()
#7 0xf5cc46c1 in bar () at test.js:6
#8 0xf5cc465f in foo () at test.js:2
#9 0xf5cc45fb in test.js () at test.js:13
#10 0xf5cbebd9 in ?? ()
#11 0xf5cb1e42 in ?? ()
(gdb) f 5
#5 0xf5cc4724 in baz () at test.js:10
10 print("inside baz");
(gdb) f 8
#8 0xf5cc465f in foo () at test.js:2
2 bar();
-------------------------------------------
This CL is as unobtrusive as possible. All tests in testsuite pass with full
integration enabled.
Current limitations:
- Only ia32 supported. Certain changes in ELF object generation should be
made
to enable it on x64.
- Information emitted in DWARF2 .line_info section is minimal and does not
cover all code, so setting breakpoints by line numbers and steping through
generated code with gdb is not possible.
- No stack unwinding information is emitted. Thus no information about
locals
and function arguments will be available in gdb for generated code.
- If V8 is compiled with snapshot no in memory ELF objects will be
generated for
code de-serialized from snapshot. Thus currently backtrace for V8 without
snapshot is more informative:
-------------------------------------------
#4 0xf5cae06e in STUB: CEntryStub ()
#5 0xf5cc3084 in baz () at test.js:10
#6 0xf5cae7ff in BUILTIN: ArgumentsAdaptorTrampoline ()
#7 0xf5cee6a9 in ?? ()
#8 0xf5cc3021 in bar () at test.js:6
#9 0xf5cc2fbf in foo () at test.js:2
#10 0xf5cc2f5b in test.js () at test.js:13
#11 0xf5caee99 in BUILTIN: JSEntryTrampoline ()
#12 0xf5cee6a9 in ?? ()
#13 0xf5cae2c2 in STUB: JSEntryStub ()
-------------------------------------------
Description:
Basic GDB JIT Interface integration.
It has certain overheads even when gdb is not attached so it is guarded by
ENABLE_GDBJIT_INTERFACE define and --gdbjit flag.
Please review this at http://codereview.chromium.org/5965011/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M SConstruct
M src/SConscript
M src/assembler.h
M src/assembler.cc
M src/bootstrapper.cc
M src/builtins.cc
M src/code-stubs.cc
M src/compiler.cc
M src/flag-definitions.h
M src/full-codegen.cc
A src/gdbjit.h
A src/gdbjit.cc
M src/mark-compact.cc
M src/stub-cache.cc
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