YJIT: Initial implementation of splat with optional params

[jimmyhmiller]

Big highlight here is reduction of iseq_splat_with_opt on railsbench from 15448. Instead we get 2029 exits for splatarray_length_not_equal. I can definitely implement it so we get rid of most (all?) of those exits as well. But wanted to keep it simple.

Before

ruby 3.3.0dev (2023-01-19T21:26:32Z upstream/master 0949cd7107) +YJIT dev [arm64-darwin22]
Command: bundle check 2> /dev/null || bundle install
The Gemfile's dependencies are satisfied
Command: bin/rails db:migrate db:seed
Using 100 posts in the database
***YJIT: Printing YJIT statistics on exit***
method call exit reasons: 
                      iseq_has_rest     107992 (31.0%)
                          block_arg      64622 (18.6%)
                        iseq_zsuper      46081 (13.2%)
                   iseq_arity_error      28708 ( 8.2%)
                iseq_ruby2_keywords      24995 ( 7.2%)
          args_splat_cfunc_var_args      16250 ( 4.7%)
                     iseq_has_no_kw      15971 ( 4.6%)
                iseq_splat_with_opt      15448 ( 4.4%)
                           kw_splat      12995 ( 3.7%)
                    iseq_has_kwrest       5294 ( 1.5%)
           iseq_missing_optional_kw       4054 ( 1.2%)
             args_splat_cfunc_zuper       2002 ( 0.6%)
                      iseq_has_post       1987 ( 0.6%)
                     refined_method        891 ( 0.3%)
              cfunc_ruby_array_varg        651 ( 0.2%)
                           keywords        102 ( 0.0%)
    args_splat_cfunc_ruby2_keywords         62 ( 0.0%)
                    args_splat_ivar         49 ( 0.0%)
                        send_getter         12 ( 0.0%)
                      zsuper_method          9 ( 0.0%)
               args_splat_optimized          5 ( 0.0%)
                    ivar_set_method          2 ( 0.0%)
                  bmethod_block_arg          2 ( 0.0%)
invokeblock exit reasons: 
               ifunc       5798 (56.1%)
                proc       2363 (22.9%)
     iseq_arg0_splat       2000 (19.4%)
    iseq_tag_changed        102 ( 1.0%)
              symbol         68 ( 0.7%)
invokesuper exit reasons: 
         block       4846 (98.2%)
    me_changed         87 ( 1.8%)
leave exit reasons: 
        interp_return    1847560 (97.7%)
    start_pc_non_zero      43884 ( 2.3%)
         se_interrupt         33 ( 0.0%)
getblockparamproxy exit reasons: 
    block_param_modified          3 (100.0%)
getinstancevariable exit reasons:
    megamorphic      13685 (100.0%)
setinstancevariable exit reasons:
    (all relevant counters are zero)
opt_aref exit reasons: 
    (all relevant counters are zero)
expandarray exit reasons: 
            splat       9974 (99.8%)
    rhs_too_small         22 ( 0.2%)
opt_getinlinecache exit reasons: 
    miss         11 (100.0%)
invalidation reasons: 
       constant_ic_fill       2006 (59.2%)
          method_lookup       1044 (30.8%)
    constant_state_bump        337 ( 9.9%)
bindings_allocations:         180
bindings_set:                   0
compiled_iseq_count:         9282
compiled_block_count:       51937
compiled_branch_count:      82230
block_next_count:           15168
defer_count:                16330
freed_iseq_count:            4051
invalidation_count:          3387
constant_state_bumps:           0
inline_code_size:         8815520
outlined_code_size:       8812960
freed_code_size:                0
code_region_size:        17678336
yjit_alloc_size:         98055804
live_page_count:             1079
freed_page_count:               0
code_gc_count:                  0
num_gc_obj_refs:            41265
object_shape_count:          2396
side_exit_count:           522816
total_exit_count:         2370376
total_insns_count:       89888726
vm_insns_count:           8734613
yjit_insns_count:        81676929
ratio_in_yjit:              90.3%
avg_len_in_yjit:             34.2
Top-20 most frequent exit ops (100.0% of exits):
    opt_send_without_block:     155299 (29.7%)
               invokesuper:     117065 (22.4%)
                      send:     104087 (19.9%)
      opt_getconstant_path:      53736 (10.3%)
               invokeblock:      37015 (7.1%)
                  opt_aref:      14087 (2.7%)
                     throw:      10587 (2.0%)
               expandarray:       9996 (1.9%)
             setlocal_WC_0:       8357 (1.6%)
                    opt_eq:       5009 (1.0%)
       getinstancevariable:       3485 (0.7%)
        getblockparamproxy:       2271 (0.4%)
               objtostring:        448 (0.1%)
          putspecialobject:        386 (0.1%)
                 opt_nil_p:        327 (0.1%)
             definesmethod:        240 (0.0%)
                checkmatch:        204 (0.0%)
                      once:        104 (0.0%)
                     leave:         34 (0.0%)
               opt_empty_p:         31 (0.0%)
itr #1: 5320ms

After

ruby 3.3.0dev (2023-01-19T22:11:54Z yjit-splat-opt-2 1704dd6a06) +YJIT dev [arm64-darwin22]
Command: bundle check 2> /dev/null || bundle install
The Gemfile's dependencies are satisfied
Command: bin/rails db:migrate db:seed
Using 100 posts in the database
***YJIT: Printing YJIT statistics on exit***
method call exit reasons: 
                      iseq_has_rest     107994 (32.3%)
                          block_arg      64624 (19.3%)
                        iseq_zsuper      46081 (13.8%)
                   iseq_arity_error      28708 ( 8.6%)
                iseq_ruby2_keywords      24995 ( 7.5%)
          args_splat_cfunc_var_args      16250 ( 4.9%)
                     iseq_has_no_kw      15971 ( 4.8%)
                           kw_splat      12995 ( 3.9%)
                    iseq_has_kwrest       5294 ( 1.6%)
           iseq_missing_optional_kw       4054 ( 1.2%)
        splatarray_length_not_equal       2029 ( 0.6%)
             args_splat_cfunc_zuper       2002 ( 0.6%)
                      iseq_has_post       1987 ( 0.6%)
                     refined_method        891 ( 0.3%)
              cfunc_ruby_array_varg        651 ( 0.2%)
                           keywords        102 ( 0.0%)
    args_splat_cfunc_ruby2_keywords         62 ( 0.0%)
                    args_splat_ivar         49 ( 0.0%)
                        send_getter         12 ( 0.0%)
                      zsuper_method          9 ( 0.0%)
               args_splat_optimized          5 ( 0.0%)
                    ivar_set_method          2 ( 0.0%)
                  bmethod_block_arg          2 ( 0.0%)
invokeblock exit reasons: 
               ifunc       5798 (56.1%)
                proc       2363 (22.9%)
     iseq_arg0_splat       2000 (19.4%)
    iseq_tag_changed        102 ( 1.0%)
              symbol         68 ( 0.7%)
invokesuper exit reasons: 
         block       4846 (98.3%)
    me_changed         86 ( 1.7%)
leave exit reasons: 
        interp_return    1847554 (97.7%)
    start_pc_non_zero      43886 ( 2.3%)
         se_interrupt         32 ( 0.0%)
getblockparamproxy exit reasons: 
    block_param_modified          3 (100.0%)
getinstancevariable exit reasons:
    megamorphic      13685 (100.0%)
setinstancevariable exit reasons:
    (all relevant counters are zero)
opt_aref exit reasons: 
    (all relevant counters are zero)
expandarray exit reasons: 
            splat       9974 (99.8%)
    rhs_too_small         22 ( 0.2%)
opt_getinlinecache exit reasons: 
    miss         11 (100.0%)
invalidation reasons: 
       constant_ic_fill       2008 (59.3%)
          method_lookup       1044 (30.8%)
    constant_state_bump        337 ( 9.9%)
bindings_allocations:         180
bindings_set:                   0
compiled_iseq_count:         9282
compiled_block_count:       51979
compiled_branch_count:      82304
block_next_count:           15179
defer_count:                16349
freed_iseq_count:            4052
invalidation_count:          3389
constant_state_bumps:           0
inline_code_size:         9056252
outlined_code_size:       9055664
freed_code_size:                0
code_region_size:        18169856
yjit_alloc_size:         98172237
live_page_count:             1109
freed_page_count:               0
code_gc_count:                  0
num_gc_obj_refs:            41318
object_shape_count:          2396
side_exit_count:           509398
total_exit_count:         2356952
total_insns_count:       89898928
vm_insns_count:           8721130
yjit_insns_count:        81687196
ratio_in_yjit:              90.3%
avg_len_in_yjit:             34.4
Top-20 most frequent exit ops (100.0% of exits):
    opt_send_without_block:     141940 (27.9%)
               invokesuper:     117064 (23.0%)
                      send:     104029 (20.4%)
      opt_getconstant_path:      53736 (10.5%)
               invokeblock:      37015 (7.3%)
                  opt_aref:      14087 (2.8%)
                     throw:      10587 (2.1%)
               expandarray:       9996 (2.0%)
             setlocal_WC_0:       8358 (1.6%)
                    opt_eq:       5008 (1.0%)
       getinstancevariable:       3485 (0.7%)
        getblockparamproxy:       2271 (0.4%)
               objtostring:        448 (0.1%)
          putspecialobject:        386 (0.1%)
                 opt_nil_p:        327 (0.1%)
             definesmethod:        240 (0.0%)
                checkmatch:        204 (0.0%)
                      once:        104 (0.0%)
                     leave:         33 (0.0%)
               opt_empty_p:         31 (0.0%)
itr #1: 5523ms