Ruby

optimize method dispatch for lead/kw params.

similar idea to r67315, provide the following optimization
for method dispatch with lead and kw parameters.

(1) add a special branch to check passing kw arguments to
a method which has lead and kw parameters.
ex) def foo(x, k:1); end; foo(0, k:1)
(2) add a special branch to check passing no-kw arguments to
a method which has lead and kw parameters.
ex) def foo(x, k:1); end; foo(0)

For (1) and (2) cases, provide special dispatchers. For (2) case,
this patch only use the special dispatcher if all default
kw parameters are literal values (nil, 1, and so on. In other case,
kw->default_values does not contains Qundef) (and no required kw
parameters becaseu they don't pass any keyword parameters).

Passing keyword arguments with a hash object is not a scope of
this patch.

Without this patch, (1) and (2) cases use setup_parameters_complex().
Especially, (2) seems frequent case for methods which extend a normal
usecase with keyword parameters (like: exception: true).

We can measure the performance with benchmark-driver:
With methods: def kw k1:1, k2:2; end
def m; end
With the following binaries:
clean-miniruby: unmodified trunk.
opt_miniruby1: use special branches for lead/kw parameters.
opt_miniruby2: use special dispatchers for lead/kw parameters.
opt_cc_miniruby: apply step (2).
Result with benchmark-driver:

 m opt_miniruby2: 75222278.0 i/s clean-miniruby: 73177896.5 i/s - 1.03x slower opt_miniruby1: 62466783.3 i/s - 1.20x slower kw opt_miniruby2: 52044504.4 i/s opt_miniruby1: 29142025.7 i/s - 1.79x slower clean-miniruby: 20515235.4 i/s - 2.54x slower kw k1: 10 opt_miniruby2: 26492219.5 i/s opt_miniruby1: 25409484.9 i/s - 1.04x slower clean-miniruby: 20235113.7 i/s - 1.31x slower kw k1: 10, k2: 20 opt_miniruby1: 24159534.0 i/s opt_miniruby2: 23470527.5 i/s - 1.03x slower clean-miniruby: 17822621.5 i/s - 1.36x slower 

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67333 b2dd03c8-39d4-4d8f-98ff-823fe69b080e