Refactor LoadIC into Handler Frontend and Backends.

Currently this mostly just moves code around.
- Later the different parts will become individual code objects that tailcall into one another.
- The mapcheck/symbol check still needs to be separated from the overall prototype-chain check so that the ICs can reuse the handlers.

Committed: https://code.google.com/p/v8/source/detail?r=13768

[Toon Verwaest, 2013-02-06 11:25:50]

PTAL

[Jakob Kummerow, 2013-02-06 12:48:27]

I think this is the right approach.

https://chromiumcodereview.appspot.com/12209021/diff/5/src/ia32/stub-cache-ia...
File src/ia32/stub-cache-ia32.cc (right):

https://chromiumcodereview.appspot.com/12209021/diff/5/src/ia32/stub-cache-ia...
src/ia32/stub-cache-ia32.cc:1227: bool must_perfrom_prototype_check =
*interceptor_holder != lookup->holder();
While you're at it: s/perfrom/perform/

https://chromiumcodereview.appspot.com/12209021/diff/5/src/stub-cache.h
File src/stub-cache.h (right):

https://chromiumcodereview.appspot.com/12209021/diff/5/src/stub-cache.h#newco...
src/stub-cache.h:584: bool perform_initial_checks);
Let's use a two-value enum here to add a bit of clarity to call sites.

[Toon Verwaest, 2013-02-06 14:06:30]

Extended the work to replace all JumpIfSmi+CheckPrototypes in LoadICs with
HandlerFrontends. Added extra comments inline.

https://chromiumcodereview.appspot.com/12209021/diff/5/src/ia32/stub-cache-ia...
File src/ia32/stub-cache-ia32.cc (right):

https://chromiumcodereview.appspot.com/12209021/diff/5/src/ia32/stub-cache-ia...
src/ia32/stub-cache-ia32.cc:1047: void
BaseLoadStubCompiler::GenerateDictionaryLoadCallback(
This got moved into CallbackHandlerFrontend directly.

https://chromiumcodereview.appspot.com/12209021/diff/5/src/ia32/stub-cache-ia...
src/ia32/stub-cache-ia32.cc:2721: 
Use other register so it looks exactly the same as another
JumpIfSmi/CheckPrototype combination.

https://chromiumcodereview.appspot.com/12209021/diff/7001/src/ia32/stub-cache...
File src/ia32/stub-cache-ia32.cc (right):

https://chromiumcodereview.appspot.com/12209021/diff/7001/src/ia32/stub-cache...
src/ia32/stub-cache-ia32.cc:3091: Label success, miss;
Kept the header/footer and stuff in between inlined, rather than generating a
special Frontend, since the body of this method doesn't do anything else than
return after the frontend succeeds. There won't be any point in jumping to a
shared stub that just returns.

[Jakob Kummerow, 2013-02-06 14:21:06]

Still looks good, go ahead and do the platform ports.

As I said before, I'd prefer an enum over "bool perform_initial_checks".

[Toon Verwaest, 2013-02-06 17:27:09]

Added ARM, x64 and turned bool into enum. PTAL again.

[Jakob Kummerow, 2013-02-11 14:11:30]

LGTM.

Let's hope our tests would catch any typos in register usage ;-)

Also, since such a large refactoring quite possibly introduces bugs, I think we
should wait until after the branching freeze before landing this.

[Toon Verwaest, 2013-02-27 15:29:01]

Committed manually as r13768 (presubmit successful).