Enable optimization of top-level code.

Enable optimization of top-level code and generate deoptimization support lazily.

This change enables optimization of top-level and eval-code. For this to work, it adds
support for declaring global variables in optimized code.

At the same time it disables the eager generation of deoptimization support data
in the full code generator (originally introduced in
 r10040). This speeds up initial compilation and saves 
memory for functions that won't be optimized. It requires
 recompiling the function with deoptimization
 support when we decide to optimize it.

Committed: https://code.google.com/p/v8/source/detail?r=10700

[fschneider, 2012-02-14 08:36:07]

Right now I only changed the default runtime profiler to only look at ticks from
top-level code if it is the top-most stack frame. There may be few more changes
necessary to enable it with your new profiler.

[Jakob Kummerow, 2012-02-14 10:08:26]

Looks good so far, just a few comments.

Waiting for an update because of that assertion failure you mentioned.

https://chromiumcodereview.appspot.com/9187005/diff/6001/src/compiler.h
File src/compiler.h (right):

https://chromiumcodereview.appspot.com/9187005/diff/6001/src/compiler.h#newcode1
src/compiler.h:1: // Copyright 2011 the V8 project authors. All rights reserved.
nit: 2012

https://chromiumcodereview.appspot.com/9187005/diff/6001/src/ia32/lithium-cod...
File src/ia32/lithium-codegen-ia32.cc (right):

https://chromiumcodereview.appspot.com/9187005/diff/6001/src/ia32/lithium-cod...
src/ia32/lithium-codegen-ia32.cc:2694: __ push(esi);  // The context is the
first argument.
How about an ASSERT(ToRegister(instr->InputAt(0)).is(esi))?

https://chromiumcodereview.appspot.com/9187005/diff/6001/src/runtime-profiler.cc
File src/runtime-profiler.cc (right):

https://chromiumcodereview.appspot.com/9187005/diff/6001/src/runtime-profiler...
src/runtime-profiler.cc:259: // Only record top-level code on top of the
execution stack and
It seems this entire addition is independent of the profiler implementation, so
please move it before the if/else block (i.e. before line 235).

[fschneider, 2012-02-14 13:03:11]

https://chromiumcodereview.appspot.com/9187005/diff/6001/src/compiler.h
File src/compiler.h (right):

https://chromiumcodereview.appspot.com/9187005/diff/6001/src/compiler.h#newcode1
src/compiler.h:1: // Copyright 2011 the V8 project authors. All rights reserved.
On 2012/02/14 10:08:26, Jakob wrote:
> nit: 2012

Done.

https://chromiumcodereview.appspot.com/9187005/diff/6001/src/ia32/lithium-cod...
File src/ia32/lithium-codegen-ia32.cc (right):

https://chromiumcodereview.appspot.com/9187005/diff/6001/src/ia32/lithium-cod...
src/ia32/lithium-codegen-ia32.cc:2694: __ push(esi);  // The context is the
first argument.
On 2012/02/14 10:08:26, Jakob wrote:
> How about an ASSERT(ToRegister(instr->InputAt(0)).is(esi))?

Done.

https://chromiumcodereview.appspot.com/9187005/diff/6001/src/runtime-profiler.cc
File src/runtime-profiler.cc (right):

https://chromiumcodereview.appspot.com/9187005/diff/6001/src/runtime-profiler...
src/runtime-profiler.cc:259: // Only record top-level code on top of the
execution stack and
On 2012/02/14 10:08:26, Jakob wrote:
> It seems this entire addition is independent of the profiler implementation,
so
> please move it before the if/else block (i.e. before line 235).

Done.

Good point. It should work with both profilers.

[Jakob Kummerow, 2012-02-14 13:08:09]

LGTM!

[Tobias Burnus, 2012-02-14 21:22:55]

Using GCC 4.7, I get "set but not used" warnings. As warnings are fatal
(-Werror), the v8 build fails.

While GCC 4.7 is not (yet) a supported compiler, I would be great if it could be
fixed nevertheless.

https://chromiumcodereview.appspot.com/9187005/diff/15002/src/compiler.cc
File src/compiler.cc (right):

https://chromiumcodereview.appspot.com/9187005/diff/15002/src/compiler.cc#new...
src/compiler.cc:218: Handle<JSFunction> closure = info->closure();
GCC 4.7 warns that closure no longer used but only set. Can the closure() line
be removed?

The patch changed the line:
  info->shared_info()->DisableOptimization(*closure);
to
  info->shared_info()->DisableOptimization();


../src/compiler.cc: In function 'bool
v8::internal::MakeCrankshaftCode(v8::internal::CompilationInfo*)':
../src/compiler.cc:218:24: error: variable 'closure' set but not used
[-Werror=unused-but-set-variable]
../src/compiler.cc:239:24: error: variable 'closure' set but not used
[-Werror=unused-but-set-variable]
../src/compiler.cc:318:24: error: variable 'closure' set but not used
[-Werror=unused-but-set-variable]
cc1plus: all warnings being treated as errors

https://chromiumcodereview.appspot.com/9187005/diff/15002/src/compiler.cc#new...
src/compiler.cc:239: Handle<JSFunction> closure = info->closure();
Ditto.

https://chromiumcodereview.appspot.com/9187005/diff/15002/src/compiler.cc#new...
src/compiler.cc:318: Handle<JSFunction> closure = info->closure();
Ditto.