* To avoid calling rb_gc_writebarrier() with an immediate value in gen_write_barrier(),
  and avoid the LIR jump issue.

Fixes https://github.com/Shopify/ruby/issues/902

This pull request adds code generation for dividing fixnums.
Testing confirms the normal case, flooring, and side-exiting on division by zero.

Its definition changes depending on e.g. whether there is YJIT in the
build.

Since we do a decent job of pre-sizing objects, don't handle the case where we would need to re-size an object. Also don't handle too-complex shapes.

lobsters stats before:

```
Top-20 calls to C functions from JIT code (79.4% of total 90,051,140):
                             rb_vm_opt_send_without_block: 19,762,433 (21.9%)
                                rb_vm_setinstancevariable:  7,698,314 ( 8.5%)
                                             rb_hash_aref:  6,767,461 ( 7.5%)
                                          rb_vm_env_write:  5,373,080 ( 6.0%)
                                               rb_vm_send:  5,049,229 ( 5.6%)
                                rb_vm_getinstancevariable:  4,535,259 ( 5.0%)
                                        rb_obj_is_kind_of:  3,746,306 ( 4.2%)
                           rb_ivar_get_at_no_ractor_check:  3,745,237 ( 4.2%)
                                        rb_vm_invokesuper:  3,037,467 ( 3.4%)
                                             rb_ary_entry:  2,351,983 ( 2.6%)
                               rb_vm_opt_getconstant_path:  1,344,740 ( 1.5%)
                                        rb_vm_invokeblock:  1,184,474 ( 1.3%)
                                                 Hash#[]=:  1,064,288 ( 1.2%)
                                       rb_gc_writebarrier:  1,006,972 ( 1.1%)
                                rb_ec_ary_new_from_values:    902,687 ( 1.0%)
                                                    fetch:    898,667 ( 1.0%)
                                        rb_str_buf_append:    833,787 ( 0.9%)
                               rb_class_allocate_instance:    822,024 ( 0.9%)
                                               Hash#fetch:    699,580 ( 0.8%)
                                                    _bi20:    682,068 ( 0.8%)
Top-4 setivar fallback reasons (100.0% of total 7,732,326):
  shape_transition: 6,032,109 (78.0%)
   not_monomorphic: 1,469,300 (19.0%)
      not_t_object:   172,636 ( 2.2%)
       too_complex:    58,281 ( 0.8%)
```

lobsters stats after:

```
Top-20 calls to C functions from JIT code (79.0% of total 88,322,656):
                             rb_vm_opt_send_without_block: 19,777,880 (22.4%)
                                             rb_hash_aref:  6,771,589 ( 7.7%)
                                          rb_vm_env_write:  5,372,789 ( 6.1%)
                                       rb_gc_writebarrier:  5,195,527 ( 5.9%)
                                               rb_vm_send:  5,049,145 ( 5.7%)
                                rb_vm_getinstancevariable:  4,538,485 ( 5.1%)
                                        rb_obj_is_kind_of:  3,746,241 ( 4.2%)
                           rb_ivar_get_at_no_ractor_check:  3,745,172 ( 4.2%)
                                        rb_vm_invokesuper:  3,037,157 ( 3.4%)
                                             rb_ary_entry:  2,351,968 ( 2.7%)
                                rb_vm_setinstancevariable:  1,703,337 ( 1.9%)
                               rb_vm_opt_getconstant_path:  1,344,730 ( 1.5%)
                                        rb_vm_invokeblock:  1,184,290 ( 1.3%)
                                                 Hash#[]=:  1,061,868 ( 1.2%)
                                rb_ec_ary_new_from_values:    902,666 ( 1.0%)
                                                    fetch:    898,666 ( 1.0%)
                                        rb_str_buf_append:    833,784 ( 0.9%)
                               rb_class_allocate_instance:    821,778 ( 0.9%)
                                               Hash#fetch:    755,913 ( 0.9%)
Top-4 setivar fallback reasons (100.0% of total 1,703,337):
            not_monomorphic: 1,472,405 (86.4%)
               not_t_object:   172,629 (10.1%)
                too_complex:    58,281 ( 3.4%)
  new_shape_needs_extension:        22 ( 0.0%)
```

I also noticed that primitive printing in HIR was broken so I fixed that.

Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>

We generally know the receiver's class from profile info. I see 600k of these when running lobsters.

* All Invariant::SingleRactorMode PatchPoint are replaced by
  assume_single_ractor_mode() to fix https://github.com/Shopify/ruby/issues/875
  for SingleRactorMode patchpoints.

Append a codepoint.

Don't support shape transitions for now.

This will make reading the parameters nicer for the JITs. Should be
no-op for the C side.

Rename to `VM_KW_SPECIFIED_BITS_MAX` now that it's in `vm_core.h`.