ES6 modules + new String

[janbiedermann]

continue work of #1970
experimental
use new String instead of string primitives to support ruby String semantics in "use strict" mode

[janbiedermann]

all strings are new String() and no primitives, at least all those cases that are covered by the tests.
Lets benchmark ...

[janbiedermann]

Benchmarks:
run in nodejs v12.1.0, one run only, possibly highly scientific

• 1_opal-1-0-0-beta1 : es6_modules_string in nodejs runner new String()
• 2_opal-1-0-0-beta1 : es6_modules_string in strictnodejs runner new String()
• 3_opal-1-0-0-beta1 : es6_modules in nodejs runner string primitives
• 4_opal-1-0-0-beta1 : es6_modules in strictnodejs runner string primitives

Base: 1_opal-1-0-0-beta1
Benchmark                                               1_opal-1-0-0-beta1 |      4_opal-1-0-0-beta1 |      2_opal-1-0-0-beta1 |      3_opal-1-0-0-beta1 | 
test/cruby/benchmark/bm_loop_times.rb                              3.840ms |      -95.84%    0.160ms |      -95.92%    0.157ms |       +9.45%    4.203ms | 
test/cruby/benchmark/bm_vm2_dstr.rb                                1.647ms |      -95.18%    0.079ms |       -2.26%    1.610ms |      -94.87%    0.085ms | 
test/cruby/benchmark/bm_vm1_gc_short_lived.rb                      5.388ms |      -93.93%    0.327ms |       -3.15%    5.219ms |      -93.55%    0.348ms | 
test/cruby/benchmark/bm_vm2_poly_method_ov.rb                      1.904ms |      -91.38%    0.164ms |      -90.81%    0.175ms |       -3.71%    1.833ms | 
test/cruby/benchmark/bm_so_nested_loop.rb                          2.882ms |      -85.70%    0.412ms |      -85.59%    0.415ms |       +8.32%    3.122ms | 
test/cruby/benchmark/bm_vm2_poly_method.rb                         1.831ms |      -76.92%    0.422ms |      -89.95%    0.184ms |       +6.92%    1.957ms | 
test/cruby/benchmark/bm_vm1_neq.rb                                 4.219ms |      -74.23%    1.087ms |      -70.76%    1.234ms |       -2.12%    4.130ms | 
test/cruby/benchmark/bm_hash_aref_str.rb                           2.606ms |      -71.67%    0.738ms |      -72.69%    0.712ms |       +8.22%    2.820ms | 
test/cruby/benchmark/bm_so_random.rb                               1.668ms |      -56.25%    0.730ms |      -53.84%    0.770ms |       +2.40%    1.708ms | 
test/cruby/benchmark/bm_so_ackermann.rb                            0.279ms |      -40.64%    0.166ms |      -42.96%    0.159ms |      -11.53%    0.247ms | 
test/cruby/benchmark/bm_vm2_send.rb                                1.424ms |      -35.45%    0.919ms |      -36.47%    0.905ms |       +6.98%    1.523ms | 
test/cruby/benchmark/bm_app_answer.rb                              0.020ms |      -30.67%    0.014ms |      -32.83%    0.013ms |       +1.99%    0.020ms | 
test/cruby/benchmark/bm_vm1_attr_ivar_set.rb                      44.378ms |      -26.41%   32.658ms |       -2.68%   43.187ms |      -23.68%   33.868ms | 
test/cruby/benchmark/bm_vm2_struct_big_aset.rb                     4.391ms |      -25.56%    3.268ms |       -1.71%    4.316ms |      -16.07%    3.685ms | 
test/cruby/benchmark/bm_vm2_struct_small_aset.rb                   4.247ms |      -25.46%    3.166ms |       -0.60%    4.222ms |      -21.47%    3.335ms | 
test/cruby/benchmark/bm_so_object.rb                               1.901ms |      -23.44%    1.455ms |      -27.23%    1.383ms |       +7.53%    2.044ms | 
test/cruby/benchmark/bm_so_lists.rb                                4.879ms |      -17.71%    4.015ms |      -25.23%    3.648ms |       -4.64%    4.653ms | 
test/cruby/benchmark/bm_vm2_struct_big_aref_lo.rb                  0.133ms |      -15.01%    0.113ms |      -11.98%    0.118ms |      -15.59%    0.113ms | 
test/cruby/benchmark/bm_vm2_zsuper.rb                              2.194ms |      -12.33%    1.923ms |      -14.68%    1.872ms |      +13.05%    2.480ms | 
test/cruby/benchmark/bm_vm2_case.rb                                5.270ms |      -10.67%    4.708ms |      -16.50%    4.401ms |       -3.37%    5.092ms | 
test/cruby/benchmark/bm_vm2_method_missing.rb                      0.081ms |      -10.65%    0.072ms |       -8.58%    0.074ms |       -5.34%    0.077ms | 
test/cruby/benchmark/bm_so_matrix.rb                               2.046ms |      -10.41%    1.833ms |       -1.46%    2.017ms |      +16.07%    2.375ms | 
test/cruby/benchmark/bm_loop_for.rb                                0.208ms |       -9.60%    0.188ms |       -5.04%    0.198ms |       -7.19%    0.193ms | 
test/cruby/benchmark/bm_vm1_not.rb                                 0.644ms |       -9.49%    0.583ms |       -8.50%    0.589ms |       -6.09%    0.605ms | 
test/cruby/benchmark/bm_vm1_swap.rb                                0.387ms |       -7.50%    0.358ms |       -8.25%    0.355ms |       -1.48%    0.381ms | 
test/cruby/benchmark/bm_hash_aref_miss.rb                          0.971ms |       -7.37%    0.899ms |      -11.29%    0.861ms |       -5.39%    0.919ms | 
test/cruby/benchmark/bm_vm3_clearmethodcache.rb                    6.286ms |       -7.13%    5.838ms |       -7.56%    5.811ms |       -1.08%    6.218ms | 
test/cruby/benchmark/bm_hash_keys.rb                               3.187ms |       -5.30%    3.018ms |       -1.92%    3.125ms |       -1.33%    3.144ms | 
test/cruby/benchmark/bm_vm2_array.rb                               0.074ms |       -4.78%    0.071ms |       -6.98%    0.069ms |       -9.00%    0.068ms | 
test/cruby/benchmark/bm_loop_whileloop.rb                          0.348ms |       -3.78%    0.335ms |       -5.56%    0.329ms |       -4.25%    0.333ms | 
test/cruby/benchmark/bm_app_tak.rb                                 0.229ms |       -3.76%    0.220ms |       -3.61%    0.220ms |       +2.76%    0.235ms | 
test/cruby/benchmark/bm_vm1_block.rb                               5.447ms |       -3.39%    5.262ms |       -1.53%    5.364ms |       +1.06%    5.505ms | 
test/cruby/benchmark/bm_vm2_super.rb                               1.347ms |       -1.32%    1.329ms |       -3.34%    1.302ms |       -3.84%    1.295ms | 
test/cruby/benchmark/bm_vm1_simplereturn.rb                        0.365ms |       -0.98%    0.361ms |       -6.98%    0.340ms |       -3.74%    0.351ms | 
test/cruby/benchmark/bm_vm2_proc.rb                                1.025ms |       -0.57%    1.019ms |       +0.85%    1.034ms |       +8.13%    1.108ms | 
test/cruby/benchmark/bm_vm2_bigarray.rb                            0.065ms |       -0.32%    0.065ms |       +1.17%    0.066ms |       +0.03%    0.065ms | 
test/cruby/benchmark/bm_hash_shift.rb                             26.586ms |       -0.02%   26.581ms |       -0.09%   26.561ms |       +5.92%   28.160ms | 
test/cruby/benchmark/bm_app_tarai.rb                               0.173ms |       +0.20%    0.174ms |       -0.34%    0.173ms |       +1.72%    0.176ms | 
test/cruby/benchmark/bm_vm2_method.rb                              0.071ms |       +0.40%    0.071ms |      +10.12%    0.078ms |      +16.99%    0.083ms | 
test/cruby/benchmark/bm_vm2_unif1.rb                               0.072ms |       +0.45%    0.072ms |       -0.79%    0.071ms |      +10.70%    0.079ms | 
test/cruby/benchmark/bm_vm1_lvar_set.rb                            0.322ms |       +0.91%    0.325ms |       -2.01%    0.316ms |       +9.19%    0.352ms | 
test/cruby/benchmark/bm_vm2_method_with_block.rb                   4.916ms |       +0.99%    4.965ms |       +0.51%    4.941ms |       +1.56%    4.993ms | 
test/cruby/benchmark/bm_vm1_lvar_init.rb                           6.904ms |       +1.74%    7.025ms |       +1.00%    6.973ms |      +25.87%    8.691ms | 
test/cruby/benchmark/bm_vm2_defined_method.rb                      0.077ms |       +2.21%    0.079ms |       +0.19%    0.077ms |      +17.20%    0.090ms | 
test/cruby/benchmark/bm_vm1_ensure.rb                              0.351ms |       +2.94%    0.361ms |       +1.09%    0.355ms |       -1.62%    0.345ms | 
test/cruby/benchmark/bm_vm1_attr_ivar.rb                           0.366ms |       +3.59%    0.380ms |       -8.68%    0.335ms |       +4.94%    0.384ms | 
test/cruby/benchmark/bm_hash_values.rb                             2.990ms |       +3.93%    3.107ms |       +3.13%    3.084ms |       +4.51%    3.125ms | 
test/cruby/benchmark/bm_vm2_newlambda.rb                           0.728ms |       +4.41%    0.760ms |       +2.77%    0.748ms |       +5.35%    0.767ms | 
test/cruby/benchmark/bm_vm1_float_simple.rb                        0.463ms |       +4.99%    0.486ms |       +4.94%    0.486ms |       +2.99%    0.477ms | 
test/cruby/benchmark/bm_app_strconcat.rb                           0.029ms |       +5.15%    0.030ms |       +1.45%    0.029ms |      +19.94%    0.035ms | 
test/cruby/benchmark/bm_app_fib.rb                                 0.153ms |       +5.24%    0.161ms |       +2.07%    0.156ms |      +10.11%    0.169ms | 
test/cruby/benchmark/bm_vm1_ivar.rb                                0.363ms |       +5.48%    0.383ms |       -3.93%    0.349ms |      +10.78%    0.403ms | 
test/cruby/benchmark/bm_vm1_yield.rb                               1.740ms |       +7.10%    1.864ms |       +3.26%    1.797ms |      +18.84%    2.068ms | 
test/cruby/benchmark/bm_vm1_ivar_set.rb                            0.341ms |       +8.16%    0.369ms |       +5.88%    0.361ms |       +2.26%    0.349ms | 
test/cruby/benchmark/bm_vm2_struct_small_aref.rb                   0.078ms |       +8.84%    0.085ms |       +8.87%    0.085ms |      +70.65%    0.134ms | 
test/cruby/benchmark/bm_loop_whileloop2.rb                         0.066ms |       +9.17%    0.072ms |       +4.73%    0.069ms |       +0.32%    0.066ms | 
test/cruby/benchmark/bm_vm1_length.rb                              0.557ms |       +9.38%    0.610ms |       +1.57%    0.566ms |      +17.66%    0.656ms | 
test/cruby/benchmark/bm_vm1_rescue.rb                              0.315ms |      +11.17%    0.351ms |       +2.16%    0.322ms |       +4.09%    0.328ms | 
test/cruby/benchmark/bm_hash_flatten.rb                            1.293ms |      +11.48%    1.442ms |       +2.19%    1.321ms |       +5.67%    1.366ms | 
test/cruby/benchmark/bm_app_factorial.rb                           0.011ms |      +12.99%    0.013ms |       -1.10%    0.011ms |      +17.83%    0.013ms | 
test/cruby/benchmark/bm_vm2_struct_big_aref_hi.rb                  0.112ms |      +22.87%    0.137ms |      +31.72%    0.147ms |      +25.66%    0.141ms | 
test/cruby/benchmark/bm_vm1_const.rb                               2.427ms |      +23.46%    2.997ms |      +10.89%    2.692ms |      +20.41%    2.923ms | 
test/cruby/benchmark/bm_vm2_bighash.rb                            17.081ms |      +98.11%   33.840ms |      -32.88%   11.466ms |      +43.34%   24.484ms |

[janbiedermann]

conclusions:

• strict mode gives a nice performance boost in nodejs v12.1.0, see run 1 vs. run 2, run 3 vs. run 4
• new String() has advantages and disadvantages, see run 1 vs. run 3, run 2 vs. run 4
• strict mode and new String() is on average faster than non strict mode with string primitives, see run 2 vs. run 3

[janbiedermann]

obsolete, Javascript 'boxed' values are to be avoided