ZJIT: Compile getblockparam (#15896)

Closes: https://github.com/Shopify/ruby/issues/863

Compile `getblockparam` insn to `GetBlockParam` HIR so that we can handle it in ZJIT.

## Benchmark 
### lobsters

<details>

<summary>before patch</summary>

```
Average of last 10, non-warmup iters: 778ms
***ZJIT: Printing ZJIT statistics on exit***
Top-20 not inlined C methods (58.4% of total 16,091,748):
                                               Hash#fetch: 3,237,974 (20.1%)
                                            Regexp#match?:   708,838 ( 4.4%)
                                                Hash#key?:   702,565 ( 4.4%)
                                              String#sub!:   489,843 ( 3.0%)
                                             Set#include?:   402,395 ( 2.5%)
                                                String#<<:   396,364 ( 2.5%)
                                       String#start_with?:   379,338 ( 2.4%)
                                              Hash#delete:   331,679 ( 2.1%)
                                               String.new:   308,268 ( 1.9%)
                                              Integer#===:   279,074 ( 1.7%)
                                         Symbol#end_with?:   255,538 ( 1.6%)
                                             Kernel#is_a?:   250,000 ( 1.6%)
                                    Process.clock_gettime:   221,598 ( 1.4%)
                                                Integer#>:   219,718 ( 1.4%)
                                            String#match?:   218,057 ( 1.4%)
                                          String#downcase:   213,127 ( 1.3%)
                                               Integer#<=:   202,617 ( 1.3%)
                                                Time#to_i:   195,248 ( 1.2%)
                                              Time#subsec:   192,277 ( 1.2%)
                                                Time#utc?:   188,500 ( 1.2%)
Top-20 calls to C functions from JIT code (83.4% of total 126,501,142):
                             rb_vm_opt_send_without_block: 35,338,443 (27.9%)
                                               rb_vm_send: 10,126,272 ( 8.0%)
                                             rb_hash_aref:  9,221,146 ( 7.3%)
                                          rb_vm_env_write:  8,615,394 ( 6.8%)
                     rb_zjit_writebarrier_check_immediate:  7,666,061 ( 6.1%)
                                rb_vm_getinstancevariable:  5,902,473 ( 4.7%)
                           rb_ivar_get_at_no_ractor_check:  4,775,750 ( 3.8%)
                                        rb_obj_is_kind_of:  3,718,303 ( 2.9%)
                                        rb_vm_invokesuper:  2,705,394 ( 2.1%)
                                             rb_hash_aset:  2,422,892 ( 1.9%)
                                rb_vm_setinstancevariable:  2,385,262 ( 1.9%)
                               rb_vm_opt_getconstant_path:  2,321,875 ( 1.8%)
                                               Hash#fetch:  1,819,675 ( 1.4%)
                                                    fetch:  1,418,299 ( 1.1%)
                                        rb_vm_invokeblock:  1,387,466 ( 1.1%)
                                        rb_str_buf_append:  1,378,634 ( 1.1%)
                                rb_ec_ary_new_from_values:  1,338,599 ( 1.1%)
                               rb_class_allocate_instance:  1,300,827 ( 1.0%)
                                    rb_hash_new_with_size:    906,352 ( 0.7%)
                                        rb_vm_sendforward:    799,626 ( 0.6%)
Top-2 not optimized method types for send (100.0% of total 5,166,211):
  iseq: 5,163,389 (99.9%)
  null:     2,822 ( 0.1%)
Top-3 not optimized method types for send_without_block (100.0% of total 526,119):
        optimized_send: 479,643 (91.2%)
                  null:  42,176 ( 8.0%)
  optimized_block_call:   4,300 ( 0.8%)
Top-3 not optimized method types for super (100.0% of total 2,365,999):
    cfunc: 2,251,438 (95.2%)
    alias:   111,257 ( 4.7%)
  attrset:     3,304 ( 0.1%)
Top-3 instructions with uncategorized fallback reason (100.0% of total 2,214,821):
             invokeblock: 1,387,466 (62.6%)
             sendforward:   799,626 (36.1%)
  opt_send_without_block:    27,729 ( 1.3%)
Top-20 send fallback reasons (100.0% of total 50,357,201):
                          send_without_block_polymorphic: 18,307,466 (36.4%)
                                    singleton_class_seen:  9,310,336 (18.5%)
                          send_not_optimized_method_type:  5,166,211 (10.3%)
                          send_without_block_no_profiles:  4,756,165 ( 9.4%)
                            one_or_more_complex_arg_pass:  2,906,412 ( 5.8%)
                                        send_no_profiles:  2,864,323 ( 5.7%)
                         super_not_optimized_method_type:  2,365,999 ( 4.7%)
                                           uncategorized:  2,214,821 ( 4.4%)
                          send_without_block_megamorphic:    581,552 ( 1.2%)
  send_without_block_not_optimized_method_type_optimized:    483,943 ( 1.0%)
        send_without_block_not_optimized_need_permission:    390,364 ( 0.8%)
                                        send_polymorphic:    329,064 ( 0.7%)
                                   too_many_args_for_lir:    173,570 ( 0.3%)
                          super_target_complex_args_pass:    131,841 ( 0.3%)
                                 super_complex_args_pass:    111,056 ( 0.2%)
                                       super_polymorphic:     86,986 ( 0.2%)
                                     argc_param_mismatch:     48,546 ( 0.1%)
            send_without_block_not_optimized_method_type:     42,176 ( 0.1%)
              send_without_block_direct_keyword_mismatch:     37,484 ( 0.1%)
                                obj_to_string_not_string:     34,865 ( 0.1%)
Top-4 setivar fallback reasons (100.0% of total 2,385,262):
            not_monomorphic: 2,162,525 (90.7%)
               not_t_object:   125,178 ( 5.2%)
                too_complex:    97,538 ( 4.1%)
  new_shape_needs_extension:        21 ( 0.0%)
Top-2 getivar fallback reasons (100.0% of total 6,027,586):
  not_monomorphic: 5,776,418 (95.8%)
      too_complex:   251,168 ( 4.2%)
Top-3 definedivar fallback reasons (100.0% of total 406,027):
  not_monomorphic: 397,876 (98.0%)
      too_complex:   5,122 ( 1.3%)
     not_t_object:   3,029 ( 0.7%)
Top-6 invokeblock handler (100.0% of total 1,387,466):
   monomorphic_iseq: 700,051 (50.5%)
        polymorphic: 513,455 (37.0%)
  monomorphic_other: 106,268 ( 7.7%)
  monomorphic_ifunc:  55,505 ( 4.0%)
        megamorphic:   6,762 ( 0.5%)
        no_profiles:   5,425 ( 0.4%)
Top-9 popular complex argument-parameter features not optimized (100.0% of total 3,353,961):
       param_kw_opt: 1,408,663 (42.0%)
  param_forwardable:   697,209 (20.8%)
        param_block:   632,488 (18.9%)
         param_rest:   346,363 (10.3%)
       param_kwrest:   139,856 ( 4.2%)
    caller_kw_splat:    79,861 ( 2.4%)
       caller_splat:    43,585 ( 1.3%)
    caller_blockarg:     5,826 ( 0.2%)
       caller_kwarg:       110 ( 0.0%)
Top-1 compile error reasons (100.0% of total 188,362):
  exception_handler: 188,362 (100.0%)
Top-7 unhandled YARV insns (100.0% of total 184,408):
       getblockparam: 95,129 (51.6%)
  invokesuperforward: 81,668 (44.3%)
         getconstant:  3,318 ( 1.8%)
       setblockparam:  2,837 ( 1.5%)
          checkmatch:    929 ( 0.5%)
         expandarray:    360 ( 0.2%)
                once:    167 ( 0.1%)
Top-3 unhandled HIR insns (100.0% of total 237,876):
          throw: 199,380 (83.8%)
  invokebuiltin:  35,775 (15.0%)
      array_max:   2,721 ( 1.1%)
Top-20 side exit reasons (100.0% of total 15,592,861):
                   guard_type_failure: 6,993,070 (44.8%)
                  guard_shape_failure: 6,862,785 (44.0%)
  block_param_proxy_not_iseq_or_ifunc: 1,006,781 ( 6.5%)
                   unhandled_hir_insn:   237,876 ( 1.5%)
                        compile_error:   188,362 ( 1.2%)
                  unhandled_yarv_insn:   184,408 ( 1.2%)
           block_param_proxy_modified:    29,130 ( 0.2%)
     patchpoint_stable_constant_names:    22,145 ( 0.1%)
         unhandled_newarray_send_pack:    14,481 ( 0.1%)
                  unhandled_block_arg:    13,788 ( 0.1%)
                 fixnum_mult_overflow:    10,866 ( 0.1%)
               fixnum_lshift_overflow:    10,085 ( 0.1%)
              patchpoint_no_ep_escape:     7,815 ( 0.1%)
                  expandarray_failure:     4,533 ( 0.0%)
             guard_super_method_entry:     4,475 ( 0.0%)
          patchpoint_method_redefined:     1,212 ( 0.0%)
        patchpoint_no_singleton_class:       423 ( 0.0%)
               obj_to_string_fallback:       330 ( 0.0%)
                   guard_less_failure:       163 ( 0.0%)
                            interrupt:       114 ( 0.0%)
                             send_count: 152,442,683
                     dynamic_send_count:  50,357,201 (33.0%)
                   optimized_send_count: 102,085,482 (67.0%)
                  dynamic_setivar_count:   2,385,262 ( 1.6%)
                  dynamic_getivar_count:   6,027,586 ( 4.0%)
              dynamic_definedivar_count:     406,027 ( 0.3%)
              iseq_optimized_send_count:  39,671,621 (26.0%)
      inline_cfunc_optimized_send_count:  42,053,762 (27.6%)
       inline_iseq_optimized_send_count:   3,462,562 ( 2.3%)
non_variadic_cfunc_optimized_send_count:   9,195,248 ( 6.0%)
    variadic_cfunc_optimized_send_count:   7,702,289 ( 5.1%)
compiled_iseq_count:                              5,552
failed_iseq_count:                                    0
compile_time:                                   1,926ms
profile_time:                                      20ms
gc_time:                                           27ms
invalidation_time:                                531ms
vm_write_pc_count:                          132,750,117
vm_write_sp_count:                          132,750,117
vm_write_locals_count:                      128,780,465
vm_write_stack_count:                       128,780,465
vm_write_to_parent_iseq_local_count:            694,799
vm_read_from_parent_iseq_local_count:        14,812,747
guard_type_count:                           159,813,452
guard_type_exit_ratio:                             4.4%
guard_shape_count:                                    0
code_region_bytes:                           29,425,664
zjit_alloc_bytes:                            44,592,776
total_mem_bytes:                             74,018,440
side_exit_count:                             15,592,861
total_insn_count:                           938,453,078
vm_insn_count:                              167,693,539
zjit_insn_count:                            770,759,539
ratio_in_zjit:                                    82.1%

```

</details>

<details>

<summary>after patch</summary>

```
Average of last 10, non-warmup iters: 725ms
***ZJIT: Printing ZJIT statistics on exit***
Top-20 not inlined C methods (58.2% of total 16,004,664):
                                               Hash#fetch: 3,185,115 (19.9%)
                                            Regexp#match?:   708,806 ( 4.4%)
                                                Hash#key?:   702,551 ( 4.4%)
                                              String#sub!:   489,841 ( 3.1%)
                                             Set#include?:   396,625 ( 2.5%)
                                                String#<<:   396,279 ( 2.5%)
                                       String#start_with?:   379,337 ( 2.4%)
                                              Hash#delete:   331,667 ( 2.1%)
                                               String.new:   307,248 ( 1.9%)
                                              Integer#===:   279,054 ( 1.7%)
                                         Symbol#end_with?:   255,538 ( 1.6%)
                                             Kernel#is_a?:   246,961 ( 1.5%)
                                    Process.clock_gettime:   221,588 ( 1.4%)
                                                Integer#>:   219,718 ( 1.4%)
                                            String#match?:   218,059 ( 1.4%)
                                          String#downcase:   213,109 ( 1.3%)
                                               Integer#<=:   202,617 ( 1.3%)
                                                Time#to_i:   192,211 ( 1.2%)
                                              Time#subsec:   189,240 ( 1.2%)
                                            String#to_sym:   185,947 ( 1.2%)
Top-20 calls to C functions from JIT code (83.4% of total 126,772,007):
                             rb_vm_opt_send_without_block: 35,829,863 (28.3%)
                                               rb_vm_send: 10,108,894 ( 8.0%)
                                             rb_hash_aref:  9,009,231 ( 7.1%)
                                          rb_vm_env_write:  8,571,665 ( 6.8%)
                     rb_zjit_writebarrier_check_immediate:  7,702,599 ( 6.1%)
                                rb_vm_getinstancevariable:  5,930,325 ( 4.7%)
                           rb_ivar_get_at_no_ractor_check:  4,764,439 ( 3.8%)
                                        rb_obj_is_kind_of:  3,722,865 ( 2.9%)
                                        rb_vm_invokesuper:  2,687,484 ( 2.1%)
                                             rb_hash_aset:  2,421,186 ( 1.9%)
                                rb_vm_setinstancevariable:  2,355,461 ( 1.9%)
                               rb_vm_opt_getconstant_path:  2,295,528 ( 1.8%)
                                               Hash#fetch:  1,779,524 ( 1.4%)
                                                    fetch:  1,405,591 ( 1.1%)
                                        rb_vm_invokeblock:  1,385,989 ( 1.1%)
                                        rb_str_buf_append:  1,369,177 ( 1.1%)
                                rb_ec_ary_new_from_values:  1,337,865 ( 1.1%)
                               rb_class_allocate_instance:  1,295,755 ( 1.0%)
                                    rb_hash_new_with_size:    902,684 ( 0.7%)
                                        rb_vm_sendforward:    798,572 ( 0.6%)
Top-2 not optimized method types for send (100.0% of total 4,902,716):
  iseq: 4,899,894 (99.9%)
  null:     2,822 ( 0.1%)
Top-3 not optimized method types for send_without_block (100.0% of total 526,064):
        optimized_send: 479,589 (91.2%)
                  null:  42,176 ( 8.0%)
  optimized_block_call:   4,299 ( 0.8%)
Top-3 not optimized method types for super (100.0% of total 2,350,245):
    cfunc: 2,239,567 (95.3%)
    alias:   107,374 ( 4.6%)
  attrset:     3,304 ( 0.1%)
Top-3 instructions with uncategorized fallback reason (100.0% of total 2,216,683):
             invokeblock: 1,385,989 (62.5%)
             sendforward:   798,572 (36.0%)
  opt_send_without_block:    32,122 ( 1.4%)
Top-20 send fallback reasons (99.9% of total 50,810,802):
                          send_without_block_polymorphic: 18,668,686 (36.7%)
                                    singleton_class_seen:  9,323,039 (18.3%)
                          send_not_optimized_method_type:  4,902,716 ( 9.6%)
                          send_without_block_no_profiles:  4,824,297 ( 9.5%)
                                        send_no_profiles:  2,853,944 ( 5.6%)
                            one_or_more_complex_arg_pass:  2,829,717 ( 5.6%)
                         super_not_optimized_method_type:  2,350,245 ( 4.6%)
                                           uncategorized:  2,216,683 ( 4.4%)
                          send_without_block_megamorphic:    723,037 ( 1.4%)
                                        send_polymorphic:    544,026 ( 1.1%)
  send_without_block_not_optimized_method_type_optimized:    483,888 ( 1.0%)
        send_without_block_not_optimized_need_permission:    390,364 ( 0.8%)
                                   too_many_args_for_lir:    172,809 ( 0.3%)
                          super_target_complex_args_pass:    128,824 ( 0.3%)
                                 super_complex_args_pass:    111,053 ( 0.2%)
                                       super_polymorphic:     87,851 ( 0.2%)
                                     argc_param_mismatch:     50,382 ( 0.1%)
            send_without_block_not_optimized_method_type:     42,176 ( 0.1%)
                                obj_to_string_not_string:     34,861 ( 0.1%)
              send_without_block_direct_keyword_mismatch:     32,436 ( 0.1%)
Top-4 setivar fallback reasons (100.0% of total 2,355,461):
            not_monomorphic: 2,132,746 (90.5%)
               not_t_object:   125,163 ( 5.3%)
                too_complex:    97,531 ( 4.1%)
  new_shape_needs_extension:        21 ( 0.0%)
Top-2 getivar fallback reasons (100.0% of total 6,055,438):
  not_monomorphic: 5,806,179 (95.9%)
      too_complex:   249,259 ( 4.1%)
Top-3 definedivar fallback reasons (100.0% of total 405,302):
  not_monomorphic: 397,150 (98.0%)
      too_complex:   5,122 ( 1.3%)
     not_t_object:   3,030 ( 0.7%)
Top-6 invokeblock handler (100.0% of total 1,385,989):
   monomorphic_iseq: 688,167 (49.7%)
        polymorphic: 523,864 (37.8%)
  monomorphic_other: 106,268 ( 7.7%)
  monomorphic_ifunc:  55,505 ( 4.0%)
        megamorphic:   6,761 ( 0.5%)
        no_profiles:   5,424 ( 0.4%)
Top-9 popular complex argument-parameter features not optimized (100.0% of total 3,234,958):
       param_kw_opt: 1,381,881 (42.7%)
  param_forwardable:   685,939 (21.2%)
        param_block:   640,948 (19.8%)
         param_rest:   327,046 (10.1%)
       param_kwrest:   120,209 ( 3.7%)
    caller_kw_splat:    38,970 ( 1.2%)
       caller_splat:    34,029 ( 1.1%)
    caller_blockarg:     5,826 ( 0.2%)
       caller_kwarg:       110 ( 0.0%)
Top-1 compile error reasons (100.0% of total 187,347):
  exception_handler: 187,347 (100.0%)
Top-6 unhandled YARV insns (100.0% of total 89,278):
  invokesuperforward: 81,667 (91.5%)
         getconstant:  3,318 ( 3.7%)
       setblockparam:  2,837 ( 3.2%)
          checkmatch:    929 ( 1.0%)
         expandarray:    360 ( 0.4%)
                once:    167 ( 0.2%)
Top-3 unhandled HIR insns (100.0% of total 236,977):
          throw: 198,481 (83.8%)
  invokebuiltin:  35,775 (15.1%)
      array_max:   2,721 ( 1.1%)
Top-20 side exit reasons (100.0% of total 15,458,443):
                   guard_type_failure: 6,918,397 (44.8%)
                  guard_shape_failure: 6,859,686 (44.4%)
  block_param_proxy_not_iseq_or_ifunc: 1,008,346 ( 6.5%)
                   unhandled_hir_insn:   236,977 ( 1.5%)
                        compile_error:   187,347 ( 1.2%)
                  unhandled_yarv_insn:    89,278 ( 0.6%)
                 fixnum_mult_overflow:    50,739 ( 0.3%)
           block_param_proxy_modified:    28,119 ( 0.2%)
     patchpoint_stable_constant_names:    22,145 ( 0.1%)
         unhandled_newarray_send_pack:    14,481 ( 0.1%)
                  unhandled_block_arg:    13,787 ( 0.1%)
               fixnum_lshift_overflow:    10,085 ( 0.1%)
              patchpoint_no_ep_escape:     7,815 ( 0.1%)
                  expandarray_failure:     4,533 ( 0.0%)
             guard_super_method_entry:     4,475 ( 0.0%)
          patchpoint_method_redefined:     1,212 ( 0.0%)
        patchpoint_no_singleton_class:       423 ( 0.0%)
               obj_to_string_fallback:       330 ( 0.0%)
                   guard_less_failure:       163 ( 0.0%)
                            interrupt:        86 ( 0.0%)
                             send_count: 151,889,096
                     dynamic_send_count:  50,810,802 (33.5%)
                   optimized_send_count: 101,078,294 (66.5%)
                  dynamic_setivar_count:   2,355,461 ( 1.6%)
                  dynamic_getivar_count:   6,055,438 ( 4.0%)
              dynamic_definedivar_count:     405,302 ( 0.3%)
              iseq_optimized_send_count:  39,470,508 (26.0%)
      inline_cfunc_optimized_send_count:  41,381,565 (27.2%)
       inline_iseq_optimized_send_count:   3,370,961 ( 2.2%)
non_variadic_cfunc_optimized_send_count:   9,210,651 ( 6.1%)
    variadic_cfunc_optimized_send_count:   7,644,609 ( 5.0%)
compiled_iseq_count:                              5,552
failed_iseq_count:                                    0
compile_time:                                   1,809ms
profile_time:                                      15ms
gc_time:                                           21ms
invalidation_time:                                526ms
vm_write_pc_count:                          132,774,559
vm_write_sp_count:                          132,774,559
vm_write_locals_count:                      128,748,998
vm_write_stack_count:                       128,748,998
vm_write_to_parent_iseq_local_count:            693,262
vm_read_from_parent_iseq_local_count:        14,737,431
guard_type_count:                           158,811,089
guard_type_exit_ratio:                             4.4%
guard_shape_count:                                    0
code_region_bytes:                           29,458,432
zjit_alloc_bytes:                            44,650,569
total_mem_bytes:                             74,109,001
side_exit_count:                             15,458,443
total_insn_count:                           934,491,306
vm_insn_count:                              166,025,364
zjit_insn_count:                            768,465,942
ratio_in_zjit:                                    82.2%
```

</details>




### rails-bench

<details>

<summary>before patch</summary>

```
Average of last 10, non-warmup iters: 1254ms
***ZJIT: Printing ZJIT statistics on exit***
Top-20 not inlined C methods (52.8% of total 39,182,033):
                                  Hash#key?: 3,141,634 ( 8.0%)
                              Regexp#match?: 2,420,227 ( 6.2%)
                                 Hash#fetch: 2,245,557 ( 5.7%)
                                 Array#any?: 1,157,418 ( 3.0%)
                                Hash#delete: 1,114,346 ( 2.8%)
                                Integer#===: 1,098,163 ( 2.8%)
                                 String.new: 1,004,713 ( 2.6%)
                               MatchData#[]:   831,442 ( 2.1%)
                                   String#b:   797,913 ( 2.0%)
                              String#to_sym:   680,943 ( 1.7%)
                                 Kernel#dup:   680,022 ( 1.7%)
                                 Array#all?:   650,132 ( 1.7%)
                              Fiber.current:   649,003 ( 1.7%)
                                 Array#join:   641,038 ( 1.6%)
                             Array#include?:   613,837 ( 1.6%)
                               Kernel#Array:   610,311 ( 1.6%)
                                  String#<<:   606,240 ( 1.5%)
                           Symbol#end_with?:   598,807 ( 1.5%)
                      String#force_encoding:   593,535 ( 1.5%)
                         Kernel#respond_to?:   550,441 ( 1.4%)
Top-20 calls to C functions from JIT code (75.2% of total 260,204,372):
               rb_vm_opt_send_without_block: 52,620,850 (20.2%)
                               rb_hash_aref: 22,920,184 ( 8.8%)
                            rb_vm_env_write: 19,484,445 ( 7.5%)
                                 rb_vm_send: 16,570,926 ( 6.4%)
       rb_zjit_writebarrier_check_immediate: 13,628,686 ( 5.2%)
                  rb_vm_getinstancevariable: 12,378,112 ( 4.8%)
             rb_ivar_get_at_no_ractor_check: 12,208,856 ( 4.7%)
                          rb_vm_invokesuper:  8,086,664 ( 3.1%)
                               rb_hash_aset:  5,043,532 ( 1.9%)
                          rb_obj_is_kind_of:  4,431,294 ( 1.7%)
                          rb_vm_invokeblock:  4,036,483 ( 1.6%)
                                  Hash#key?:  3,141,634 ( 1.2%)
                 rb_vm_opt_getconstant_path:  3,051,909 ( 1.2%)
                 rb_class_allocate_instance:  2,878,743 ( 1.1%)
                      rb_hash_new_with_size:  2,873,398 ( 1.1%)
                  rb_ec_ary_new_from_values:  2,584,790 ( 1.0%)
                     rb_str_concat_literals:  2,450,752 ( 0.9%)
                              Regexp#match?:  2,420,227 ( 0.9%)
                               rb_obj_alloc:  2,419,180 ( 0.9%)
                  rb_vm_setinstancevariable:  2,357,067 ( 0.9%)
Top-2 not optimized method types for send (100.0% of total 8,550,761):
       iseq: 8,518,290 (99.6%)
  optimized:    32,471 ( 0.4%)
Top-2 not optimized method types for send_without_block (100.0% of total 790,792):
  optimized_send: 608,036 (76.9%)
            null: 182,756 (23.1%)
Top-2 not optimized method types for super (100.0% of total 6,689,860):
    cfunc: 6,640,181 (99.3%)
  attrset:    49,679 ( 0.7%)
Top-3 instructions with uncategorized fallback reason (100.0% of total 5,911,882):
             invokeblock: 4,036,483 (68.3%)
             sendforward: 1,871,601 (31.7%)
  opt_send_without_block:     3,798 ( 0.1%)
Top-20 send fallback reasons (100.0% of total 83,186,524):
                          send_without_block_polymorphic: 33,814,235 (40.6%)
                          send_not_optimized_method_type:  8,550,761 (10.3%)
                          send_without_block_no_profiles:  8,405,471 (10.1%)
                         super_not_optimized_method_type:  6,689,860 ( 8.0%)
                                           uncategorized:  5,911,882 ( 7.1%)
                            one_or_more_complex_arg_pass:  5,502,146 ( 6.6%)
                                        send_no_profiles:  4,700,820 ( 5.7%)
                                        send_polymorphic:  3,318,564 ( 4.0%)
        send_without_block_not_optimized_need_permission:  1,274,177 ( 1.5%)
                                    singleton_class_seen:  1,101,973 ( 1.3%)
                                   too_many_args_for_lir:    905,412 ( 1.1%)
                                 super_complex_args_pass:    829,842 ( 1.0%)
  send_without_block_not_optimized_method_type_optimized:    608,036 ( 0.7%)
                          send_without_block_megamorphic:    565,874 ( 0.7%)
                          super_target_complex_args_pass:    414,600 ( 0.5%)
            send_without_block_not_optimized_method_type:    182,756 ( 0.2%)
                                obj_to_string_not_string:    158,141 ( 0.2%)
                                   super_call_with_block:    100,004 ( 0.1%)
              send_without_block_direct_keyword_mismatch:     99,588 ( 0.1%)
                                       super_polymorphic:     52,358 ( 0.1%)
Top-2 setivar fallback reasons (100.0% of total 2,357,067):
  not_monomorphic: 2,255,283 (95.7%)
     not_t_object:   101,784 ( 4.3%)
Top-1 getivar fallback reasons (100.0% of total 12,378,137):
  not_monomorphic: 12,378,137 (100.0%)
Top-2 definedivar fallback reasons (100.0% of total 350,548):
  not_monomorphic: 350,461 (100.0%)
     not_t_object:      87 ( 0.0%)
Top-6 invokeblock handler (100.0% of total 4,036,483):
   monomorphic_iseq: 2,189,057 (54.2%)
        polymorphic: 1,207,002 (29.9%)
  monomorphic_other:   334,248 ( 8.3%)
  monomorphic_ifunc:   221,225 ( 5.5%)
        megamorphic:    84,439 ( 2.1%)
        no_profiles:       512 ( 0.0%)
Top-9 popular complex argument-parameter features not optimized (100.0% of total 7,096,505):
       param_kw_opt: 1,834,705 (25.9%)
  param_forwardable: 1,824,953 (25.7%)
        param_block: 1,792,214 (25.3%)
         param_rest:   861,894 (12.1%)
    caller_kw_splat:   297,937 ( 4.2%)
       caller_splat:   283,669 ( 4.0%)
       param_kwrest:   200,208 ( 2.8%)
    caller_blockarg:       752 ( 0.0%)
       caller_kwarg:       173 ( 0.0%)
Top-1 compile error reasons (100.0% of total 391,562):
  exception_handler: 391,562 (100.0%)
Top-7 unhandled YARV insns (100.0% of total 1,899,393):
       getblockparam: 898,862 (47.3%)
  invokesuperforward: 498,993 (26.3%)
         getconstant: 400,945 (21.1%)
         expandarray:  49,985 ( 2.6%)
       setblockparam:  49,972 ( 2.6%)
          checkmatch:     480 ( 0.0%)
                once:     156 ( 0.0%)
Top-2 unhandled HIR insns (100.0% of total 268,151):
          throw: 232,560 (86.7%)
  invokebuiltin:  35,591 (13.3%)
Top-19 side exit reasons (100.0% of total 9,609,677):
                  guard_shape_failure: 2,498,160 (26.0%)
  block_param_proxy_not_iseq_or_ifunc: 1,988,408 (20.7%)
                  unhandled_yarv_insn: 1,899,393 (19.8%)
                   guard_type_failure: 1,722,167 (17.9%)
                        compile_error:   391,562 ( 4.1%)
         unhandled_newarray_send_pack:   298,017 ( 3.1%)
                   unhandled_hir_insn:   268,151 ( 2.8%)
          patchpoint_method_redefined:   200,632 ( 2.1%)
                  unhandled_block_arg:   151,295 ( 1.6%)
           block_param_proxy_modified:   124,245 ( 1.3%)
                   guard_less_failure:    50,126 ( 0.5%)
               fixnum_lshift_overflow:     9,985 ( 0.1%)
     patchpoint_stable_constant_names:     6,366 ( 0.1%)
                 fixnum_mult_overflow:       570 ( 0.0%)
               obj_to_string_fallback:       429 ( 0.0%)
              patchpoint_no_ep_escape:       109 ( 0.0%)
                            interrupt:        48 ( 0.0%)
             guard_super_method_entry:         8 ( 0.0%)
             guard_greater_eq_failure:         6 ( 0.0%)
                             send_count: 328,547,991
                     dynamic_send_count:  83,186,524 (25.3%)
                   optimized_send_count: 245,361,467 (74.7%)
                  dynamic_setivar_count:   2,357,067 ( 0.7%)
                  dynamic_getivar_count:  12,378,137 ( 3.8%)
              dynamic_definedivar_count:     350,548 ( 0.1%)
              iseq_optimized_send_count:  93,424,465 (28.4%)
      inline_cfunc_optimized_send_count:  98,338,280 (29.9%)
       inline_iseq_optimized_send_count:   9,338,763 ( 2.8%)
non_variadic_cfunc_optimized_send_count:  26,452,910 ( 8.1%)
    variadic_cfunc_optimized_send_count:  17,807,049 ( 5.4%)
compiled_iseq_count:                               2,887
failed_iseq_count:                                     0
compile_time:                                      877ms
profile_time:                                       32ms
gc_time:                                            11ms
invalidation_time:                                  15ms
vm_write_pc_count:                           284,341,923
vm_write_sp_count:                           284,341,923
vm_write_locals_count:                       272,137,494
vm_write_stack_count:                        272,137,494
vm_write_to_parent_iseq_local_count:           1,079,867
vm_read_from_parent_iseq_local_count:         30,816,135
guard_type_count:                            313,667,907
guard_type_exit_ratio:                              0.5%
guard_shape_count:                                     0
code_region_bytes:                            14,417,920
zjit_alloc_bytes:                             19,075,183
total_mem_bytes:                              33,493,103
side_exit_count:                               9,609,677
total_insn_count:                          1,706,360,231
vm_insn_count:                               124,793,155
zjit_insn_count:                           1,581,567,076
ratio_in_zjit:                                     92.7%
```

</details>

<details>

<summary>after patch</summary>

```
Average of last 10, non-warmup iters: 1136ms
***ZJIT: Printing ZJIT statistics on exit***
Top-20 not inlined C methods (52.8% of total 39,182,033):
                                  Hash#key?: 3,141,634 ( 8.0%)
                              Regexp#match?: 2,420,227 ( 6.2%)
                                 Hash#fetch: 2,245,557 ( 5.7%)
                                 Array#any?: 1,157,418 ( 3.0%)
                                Hash#delete: 1,114,346 ( 2.8%)
                                Integer#===: 1,098,163 ( 2.8%)
                                 String.new: 1,004,713 ( 2.6%)
                               MatchData#[]:   831,442 ( 2.1%)
                                   String#b:   797,913 ( 2.0%)
                              String#to_sym:   680,943 ( 1.7%)
                                 Kernel#dup:   680,022 ( 1.7%)
                                 Array#all?:   650,132 ( 1.7%)
                              Fiber.current:   649,003 ( 1.7%)
                                 Array#join:   641,038 ( 1.6%)
                             Array#include?:   613,837 ( 1.6%)
                               Kernel#Array:   610,311 ( 1.6%)
                                  String#<<:   606,240 ( 1.5%)
                           Symbol#end_with?:   598,807 ( 1.5%)
                      String#force_encoding:   593,535 ( 1.5%)
                         Kernel#respond_to?:   550,441 ( 1.4%)
Top-20 calls to C functions from JIT code (74.8% of total 261,805,313):
               rb_vm_opt_send_without_block: 52,621,173 (20.1%)
                               rb_hash_aref: 22,920,184 ( 8.8%)
                            rb_vm_env_write: 19,484,925 ( 7.4%)
                                 rb_vm_send: 16,571,020 ( 6.3%)
       rb_zjit_writebarrier_check_immediate: 13,780,332 ( 5.3%)
                  rb_vm_getinstancevariable: 12,378,114 ( 4.7%)
             rb_ivar_get_at_no_ractor_check: 12,208,856 ( 4.7%)
                          rb_vm_invokesuper:  8,086,666 ( 3.1%)
                               rb_hash_aset:  5,043,537 ( 1.9%)
                          rb_obj_is_kind_of:  4,431,299 ( 1.7%)
                          rb_vm_invokeblock:  4,036,481 ( 1.5%)
                                  Hash#key?:  3,141,634 ( 1.2%)
                 rb_vm_opt_getconstant_path:  3,051,909 ( 1.2%)
                 rb_class_allocate_instance:  2,878,746 ( 1.1%)
                      rb_hash_new_with_size:  2,873,398 ( 1.1%)
                  rb_ec_ary_new_from_values:  2,585,224 ( 1.0%)
                     rb_str_concat_literals:  2,450,752 ( 0.9%)
                              Regexp#match?:  2,420,227 ( 0.9%)
                               rb_obj_alloc:  2,419,182 ( 0.9%)
                  rb_vm_setinstancevariable:  2,357,067 ( 0.9%)
Top-2 not optimized method types for send (100.0% of total 8,550,761):
       iseq: 8,518,290 (99.6%)
  optimized:    32,471 ( 0.4%)
Top-2 not optimized method types for send_without_block (100.0% of total 790,792):
  optimized_send: 608,036 (76.9%)
            null: 182,756 (23.1%)
Top-2 not optimized method types for super (100.0% of total 6,689,860):
    cfunc: 6,640,181 (99.3%)
  attrset:    49,679 ( 0.7%)
Top-3 instructions with uncategorized fallback reason (100.0% of total 5,911,883):
             invokeblock: 4,036,481 (68.3%)
             sendforward: 1,871,601 (31.7%)
  opt_send_without_block:     3,801 ( 0.1%)
Top-20 send fallback reasons (100.0% of total 83,186,941):
                          send_without_block_polymorphic: 33,814,528 (40.6%)
                          send_not_optimized_method_type:  8,550,761 (10.3%)
                          send_without_block_no_profiles:  8,405,497 (10.1%)
                         super_not_optimized_method_type:  6,689,860 ( 8.0%)
                                           uncategorized:  5,911,883 ( 7.1%)
                            one_or_more_complex_arg_pass:  5,502,147 ( 6.6%)
                                        send_no_profiles:  4,700,820 ( 5.7%)
                                        send_polymorphic:  3,318,658 ( 4.0%)
        send_without_block_not_optimized_need_permission:  1,274,177 ( 1.5%)
                                    singleton_class_seen:  1,101,973 ( 1.3%)
                                   too_many_args_for_lir:    905,412 ( 1.1%)
                                 super_complex_args_pass:    829,842 ( 1.0%)
  send_without_block_not_optimized_method_type_optimized:    608,036 ( 0.7%)
                          send_without_block_megamorphic:    565,874 ( 0.7%)
                          super_target_complex_args_pass:    414,600 ( 0.5%)
            send_without_block_not_optimized_method_type:    182,756 ( 0.2%)
                                obj_to_string_not_string:    158,141 ( 0.2%)
                                   super_call_with_block:    100,004 ( 0.1%)
              send_without_block_direct_keyword_mismatch:     99,588 ( 0.1%)
                                       super_polymorphic:     52,360 ( 0.1%)
Top-2 setivar fallback reasons (100.0% of total 2,357,067):
  not_monomorphic: 2,255,283 (95.7%)
     not_t_object:   101,784 ( 4.3%)
Top-1 getivar fallback reasons (100.0% of total 12,378,139):
  not_monomorphic: 12,378,139 (100.0%)
Top-2 definedivar fallback reasons (100.0% of total 350,548):
  not_monomorphic: 350,461 (100.0%)
     not_t_object:      87 ( 0.0%)
Top-6 invokeblock handler (100.0% of total 4,036,481):
   monomorphic_iseq: 2,189,057 (54.2%)
        polymorphic: 1,207,002 (29.9%)
  monomorphic_other:   334,248 ( 8.3%)
  monomorphic_ifunc:   221,223 ( 5.5%)
        megamorphic:    84,439 ( 2.1%)
        no_profiles:       512 ( 0.0%)
Top-9 popular complex argument-parameter features not optimized (100.0% of total 7,096,506):
       param_kw_opt: 1,834,706 (25.9%)
  param_forwardable: 1,824,953 (25.7%)
        param_block: 1,792,214 (25.3%)
         param_rest:   861,894 (12.1%)
    caller_kw_splat:   297,937 ( 4.2%)
       caller_splat:   283,669 ( 4.0%)
       param_kwrest:   200,208 ( 2.8%)
    caller_blockarg:       752 ( 0.0%)
       caller_kwarg:       173 ( 0.0%)
Top-1 compile error reasons (100.0% of total 391,562):
  exception_handler: 391,562 (100.0%)
Top-6 unhandled YARV insns (100.0% of total 1,000,531):
  invokesuperforward: 498,993 (49.9%)
         getconstant: 400,945 (40.1%)
         expandarray:  49,985 ( 5.0%)
       setblockparam:  49,972 ( 5.0%)
          checkmatch:     480 ( 0.0%)
                once:     156 ( 0.0%)
Top-2 unhandled HIR insns (100.0% of total 268,154):
          throw: 232,560 (86.7%)
  invokebuiltin:  35,594 (13.3%)
Top-19 side exit reasons (100.0% of total 8,710,811):
                  guard_shape_failure: 2,498,161 (28.7%)
  block_param_proxy_not_iseq_or_ifunc: 1,988,408 (22.8%)
                   guard_type_failure: 1,722,168 (19.8%)
                  unhandled_yarv_insn: 1,000,531 (11.5%)
                        compile_error:   391,562 ( 4.5%)
         unhandled_newarray_send_pack:   298,017 ( 3.4%)
                   unhandled_hir_insn:   268,154 ( 3.1%)
          patchpoint_method_redefined:   200,632 ( 2.3%)
                  unhandled_block_arg:   151,295 ( 1.7%)
           block_param_proxy_modified:   124,245 ( 1.4%)
                   guard_less_failure:    50,126 ( 0.6%)
               fixnum_lshift_overflow:     9,985 ( 0.1%)
     patchpoint_stable_constant_names:     6,366 ( 0.1%)
                 fixnum_mult_overflow:       570 ( 0.0%)
               obj_to_string_fallback:       429 ( 0.0%)
              patchpoint_no_ep_escape:       109 ( 0.0%)
                            interrupt:        39 ( 0.0%)
             guard_super_method_entry:         8 ( 0.0%)
             guard_greater_eq_failure:         6 ( 0.0%)
                             send_count: 328,747,903
                     dynamic_send_count:  83,186,941 (25.3%)
                   optimized_send_count: 245,560,962 (74.7%)
                  dynamic_setivar_count:   2,357,067 ( 0.7%)
                  dynamic_getivar_count:  12,378,139 ( 3.8%)
              dynamic_definedivar_count:     350,548 ( 0.1%)
              iseq_optimized_send_count:  93,623,831 (28.5%)
      inline_cfunc_optimized_send_count:  98,338,311 (29.9%)
       inline_iseq_optimized_send_count:   9,338,766 ( 2.8%)
non_variadic_cfunc_optimized_send_count:  26,453,005 ( 8.0%)
    variadic_cfunc_optimized_send_count:  17,807,049 ( 5.4%)
compiled_iseq_count:                               2,888
failed_iseq_count:                                     0
compile_time:                                      858ms
profile_time:                                       29ms
gc_time:                                            59ms
invalidation_time:                                  15ms
vm_write_pc_count:                           285,990,091
vm_write_sp_count:                           285,990,091
vm_write_locals_count:                       272,886,376
vm_write_stack_count:                        272,886,376
vm_write_to_parent_iseq_local_count:           1,079,877
vm_read_from_parent_iseq_local_count:         30,816,135
guard_type_count:                            314,169,071
guard_type_exit_ratio:                              0.5%
guard_shape_count:                                     0
code_region_bytes:                            14,401,536
zjit_alloc_bytes:                             19,128,598
total_mem_bytes:                              33,530,134
side_exit_count:                               8,710,811
total_insn_count:                          1,705,461,649
vm_insn_count:                               121,244,824
zjit_insn_count:                           1,584,216,825
ratio_in_zjit:                                     92.9%
```

</details>

6 files changed, 336 insertions, 0 deletions

diff --git a/test/ruby/test_zjit.rb b/test/ruby/test_zjit.rb
index e347986abc..2066610cb2 100644
--- a/test/ruby/test_zjit.rb
+++ b/test/ruby/test_zjit.rb
@@ -470,6 +470,42 @@ class TestZJIT < Test::Unit::TestCase
     }, insns: [:getblockparamproxy]
   end
 
+  def test_getblockparam
+    assert_compiles '2', %q{
+      def test(&blk)
+        blk
+      end
+      test { 2 }.call
+      test { 2 }.call
+    }, insns: [:getblockparam]
+  end
+
+  def test_getblockparam_proxy_side_exit_restores_block_local
+    assert_compiles '2', %q{
+      def test(&block)
+        b = block
+        # sideexits here
+        raise "test" unless block
+        b ? 2 : 3
+      end
+      test {}
+      test {}
+    }, insns: [:getblockparam, :getblockparamproxy]
+  end
+
+  def test_getblockparam_used_twice_in_args
+    assert_compiles '1', %q{
+      def f(*args) = args
+      def test(&blk)
+        b = blk
+        f(*[1], blk)
+        blk
+      end
+      test {1}.call
+      test {1}.call
+    }, insns: [:getblockparam]
+  end
+
   def test_optimized_method_call_proc_call
     assert_compiles '2', %q{
       p = proc { |x| x * 2 }
diff --git a/zjit/src/codegen.rs b/zjit/src/codegen.rs
index 0030493ddf..870fe7584a 100644
--- a/zjit/src/codegen.rs
+++ b/zjit/src/codegen.rs
@@ -550,6 +550,8 @@ fn gen_insn(cb: &mut CodeBlock, jit: &mut JITState, asm: &mut Assembler, functio
         Insn::SetGlobal { id, val, state } => no_output!(gen_setglobal(jit, asm, *id, opnd!(val), &function.frame_state(*state))),
         Insn::GetGlobal { id, state } => gen_getglobal(jit, asm, *id, &function.frame_state(*state)),
         &Insn::GetLocal { ep_offset, level, use_sp, .. } => gen_getlocal(asm, ep_offset, level, use_sp),
+        &Insn::IsBlockParamModified { level } => gen_is_block_param_modified(asm, level),
+        &Insn::GetBlockParam { ep_offset, level, state } => gen_getblockparam(jit, asm, ep_offset, level, &function.frame_state(state)),
         &Insn::SetLocal { val, ep_offset, level } => no_output!(gen_setlocal(asm, opnd!(val), function.type_of(val), ep_offset, level)),
         Insn::GetConstantPath { ic, state } => gen_get_constant_path(jit, asm, *ic, &function.frame_state(*state)),
         Insn::GetClassVar { id, ic, state } => gen_getclassvar(jit, asm, *id, *ic, &function.frame_state(*state)),
@@ -743,6 +745,46 @@ fn gen_setlocal(asm: &mut Assembler, val: Opnd, val_type: Type, local_ep_offset:
     }
 }
 
+/// Returns 1 (as CBool) when VM_FRAME_FLAG_MODIFIED_BLOCK_PARAM is set; returns 0 otherwise.
+fn gen_is_block_param_modified(asm: &mut Assembler, level: u32) -> Opnd {
+    let ep = gen_get_ep(asm, level);
+    let flags = asm.load(Opnd::mem(VALUE_BITS, ep, SIZEOF_VALUE_I32 * (VM_ENV_DATA_INDEX_FLAGS as i32)));
+    asm.test(flags, VM_FRAME_FLAG_MODIFIED_BLOCK_PARAM.into());
+    asm.csel_nz(Opnd::Imm(1), Opnd::Imm(0))
+}
+
+/// Get the block parameter as a Proc, write it to the environment,
+/// and mark the flag as modified.
+fn gen_getblockparam(jit: &mut JITState, asm: &mut Assembler, ep_offset: u32, level: u32, state: &FrameState) -> Opnd {
+    gen_prepare_leaf_call_with_gc(asm, state);
+    // Bail out if write barrier is required.
+    let ep = gen_get_ep(asm, level);
+    let flags = Opnd::mem(VALUE_BITS, ep, SIZEOF_VALUE_I32 * (VM_ENV_DATA_INDEX_FLAGS as i32));
+    asm.test(flags, VM_ENV_FLAG_WB_REQUIRED.into());
+    asm.jnz(side_exit(jit, state, SideExitReason::BlockParamWbRequired));
+
+    // Convert block handler to Proc.
+    let block_handler = asm.load(Opnd::mem(VALUE_BITS, ep, SIZEOF_VALUE_I32 * VM_ENV_DATA_INDEX_SPECVAL));
+    let proc = asm_ccall!(asm, rb_vm_bh_to_procval, EC, block_handler);
+
+    // Write Proc to EP and mark modified.
+    let ep = gen_get_ep(asm, level);
+    let local_ep_offset = c_int::try_from(ep_offset).unwrap_or_else(|_| {
+        panic!("Could not convert local_ep_offset {ep_offset} to i32")
+    });
+    let offset = -(SIZEOF_VALUE_I32 * local_ep_offset);
+    asm.mov(Opnd::mem(VALUE_BITS, ep, offset), proc);
+
+    let flags = Opnd::mem(VALUE_BITS, ep, SIZEOF_VALUE_I32 * (VM_ENV_DATA_INDEX_FLAGS as i32));
+    let flags_val = asm.load(flags);
+    let modified = asm.or(flags_val, VM_FRAME_FLAG_MODIFIED_BLOCK_PARAM.into());
+    asm.store(flags, modified);
+
+    // Read the Proc from EP.
+    let ep = gen_get_ep(asm, level);
+    asm.load(Opnd::mem(VALUE_BITS, ep, offset))
+}
+
 fn gen_guard_block_param_proxy(jit: &JITState, asm: &mut Assembler, level: u32, state: &FrameState) {
     // Bail out if the `&block` local variable has been modified
     let ep = gen_get_ep(asm, level);
diff --git a/zjit/src/hir.rs b/zjit/src/hir.rs
index 4326d37b34..b4f78c025d 100644
--- a/zjit/src/hir.rs
+++ b/zjit/src/hir.rs
@@ -506,6 +506,7 @@ pub enum SideExitReason {
     Interrupt,
     BlockParamProxyModified,
     BlockParamProxyNotIseqOrIfunc,
+    BlockParamWbRequired,
     StackOverflow,
     FixnumModByZero,
     FixnumDivByZero,
@@ -839,6 +840,11 @@ pub enum Insn {
     /// If `use_sp` is true, it uses the SP register to optimize the read.
     /// `rest_param` is used by infer_types to infer the ArrayExact type.
     GetLocal { level: u32, ep_offset: u32, use_sp: bool, rest_param: bool },
+    /// Check whether VM_FRAME_FLAG_MODIFIED_BLOCK_PARAM is set in the environment flags.
+    /// Returns CBool (0/1).
+    IsBlockParamModified { level: u32 },
+    /// Get the block parameter as a Proc.
+    GetBlockParam { level: u32, ep_offset: u32, state: InsnId },
     /// Set a local variable in a higher scope or the heap
     SetLocal { level: u32, ep_offset: u32, val: InsnId },
     GetSpecialSymbol { symbol_type: SpecialBackrefSymbol, state: InsnId },
@@ -1150,6 +1156,8 @@ impl Insn {
             Insn::GetSpecialNumber { .. } => effects::Any,
             Insn::GetClassVar { .. } => effects::Any,
             Insn::SetClassVar { .. } => effects::Any,
+            Insn::IsBlockParamModified { .. } => effects::Any,
+            Insn::GetBlockParam { .. } => effects::Any,
             Insn::Snapshot { .. } => effects::Empty,
             Insn::Jump(_) => effects::Any,
             Insn::IfTrue { .. } => effects::Any,
@@ -1523,6 +1531,11 @@ impl<'a> std::fmt::Display for InsnPrinter<'a> {
             Insn::GuardGreaterEq { left, right, .. } => write!(f, "GuardGreaterEq {left}, {right}"),
             Insn::GuardSuperMethodEntry { lep, cme, .. } => write!(f, "GuardSuperMethodEntry {lep}, {:p}", self.ptr_map.map_ptr(cme)),
             Insn::GetBlockHandler { lep } => write!(f, "GetBlockHandler {lep}"),
+            &Insn::GetBlockParam { level, ep_offset, .. } => {
+                let name = get_local_var_name_for_printer(self.iseq, level, ep_offset)
+                    .map_or(String::new(), |x| format!("{x}, "));
+                write!(f, "GetBlockParam {name}l{level}, EP@{ep_offset}")
+            },
             Insn::PatchPoint { invariant, .. } => { write!(f, "PatchPoint {}", invariant.print(self.ptr_map)) },
             Insn::GetConstantPath { ic, .. } => { write!(f, "GetConstantPath {:p}", self.ptr_map.map_ptr(ic)) },
             Insn::IsBlockGiven { lep } => { write!(f, "IsBlockGiven {lep}") },
@@ -1589,6 +1602,9 @@ impl<'a> std::fmt::Display for InsnPrinter<'a> {
                 let name = get_local_var_name_for_printer(self.iseq, level, ep_offset).map_or(String::new(), |x| format!("{x}, "));
                 write!(f, "GetLocal {name}l{level}, EP@{ep_offset}{}", if rest_param { ", *" } else { "" })
             },
+            &Insn::IsBlockParamModified { level } => {
+                write!(f, "IsBlockParamModified l{level}")
+            },
             &Insn::SetLocal { val, level, ep_offset } => {
                 let name = get_local_var_name_for_printer(self.iseq, level, ep_offset).map_or(String::new(), |x| format!("{x}, "));
                 write!(f, "SetLocal {name}l{level}, EP@{ep_offset}, {val}")
@@ -2139,6 +2155,7 @@ impl Function {
                     | PutSpecialObject {..}
                     | GetGlobal {..}
                     | GetLocal {..}
+                    | IsBlockParamModified {..}
                     | SideExit {..}
                     | EntryPoint {..}
                     | LoadPC
@@ -2193,6 +2210,7 @@ impl Function {
             &GuardSuperMethodEntry { lep, cme, state } => GuardSuperMethodEntry { lep: find!(lep), cme, state },
             &GetBlockHandler { lep } => GetBlockHandler { lep: find!(lep) },
             &IsBlockGiven { lep } => IsBlockGiven { lep: find!(lep) },
+            &GetBlockParam { level, ep_offset, state } => GetBlockParam { level, ep_offset, state: find!(state) },
             &FixnumAdd { left, right, state } => FixnumAdd { left: find!(left), right: find!(right), state },
             &FixnumSub { left, right, state } => FixnumSub { left: find!(left), right: find!(right), state },
             &FixnumMult { left, right, state } => FixnumMult { left: find!(left), right: find!(right), state },
@@ -2488,6 +2506,8 @@ impl Function {
             Insn::AnyToString { .. } => types::String,
             Insn::GetLocal { rest_param: true, .. } => types::ArrayExact,
             Insn::GetLocal { .. } => types::BasicObject,
+            Insn::IsBlockParamModified { .. } => types::CBool,
+            Insn::GetBlockParam { .. } => types::BasicObject,
             Insn::GetBlockHandler { .. } => types::RubyValue,
             // The type of Snapshot doesn't really matter; it's never materialized. It's used only
             // as a reference for FrameState, which we use to generate side-exit code.
@@ -4386,6 +4406,7 @@ impl Function {
             | &Insn::GetLEP
             | &Insn::LoadSelf
             | &Insn::GetLocal { .. }
+            | &Insn::IsBlockParamModified { .. }
             | &Insn::PutSpecialObject { .. }
             | &Insn::IncrCounter(_)
             | &Insn::IncrCounterPtr { .. } =>
@@ -4396,6 +4417,7 @@ impl Function {
             }
             &Insn::PatchPoint { state, .. }
             | &Insn::CheckInterrupts { state }
+            | &Insn::GetBlockParam { state, .. }
             | &Insn::GetConstantPath { ic: _, state } => {
                 worklist.push_back(state);
             }
@@ -5153,6 +5175,8 @@ impl Function {
             | Insn::GetSpecialNumber { .. }
             | Insn::GetSpecialSymbol { .. }
             | Insn::GetLocal { .. }
+            | Insn::GetBlockParam { .. }
+            | Insn::IsBlockParamModified { .. }
             | Insn::StoreField { .. } => {
                 Ok(())
             }
@@ -6428,6 +6452,112 @@ pub fn iseq_to_hir(iseq: *const rb_iseq_t) -> Result<Function, ParseError> {
                     // TODO(Shopify/ruby#753): GC root, so we should be able to avoid unnecessary GC tracing
                     state.stack_push(fun.push_insn(block, Insn::Const { val: Const::Value(unsafe { rb_block_param_proxy }) }));
                 }
+                YARVINSN_getblockparam => {
+                    fn new_branch_block(
+                        fun: &mut Function,
+                        insn_idx: u32,
+                        exit_state: &FrameState,
+                        locals_count: usize,
+                        stack_count: usize,
+                    ) -> (BlockId, InsnId, FrameState, InsnId) {
+                        let block = fun.new_block(insn_idx);
+                        let self_param = fun.push_insn(block, Insn::Param);
+                        let mut state = exit_state.clone();
+                        state.locals.clear();
+                        state.stack.clear();
+                        state.locals.extend((0..locals_count).map(|_| fun.push_insn(block, Insn::Param)));
+                        state.stack.extend((0..stack_count).map(|_| fun.push_insn(block, Insn::Param)));
+                        let snapshot = fun.push_insn(block, Insn::Snapshot { state: state.clone() });
+                        (block, self_param, state, snapshot)
+                    }
+
+                    fn finish_getblockparam_branch(
+                        fun: &mut Function,
+                        block: BlockId,
+                        self_param: InsnId,
+                        state: &mut FrameState,
+                        join_block: BlockId,
+                        ep_offset: u32,
+                        level: u32,
+                        val: InsnId,
+                    ) {
+                        if level == 0 {
+                            state.setlocal(ep_offset, val);
+                        }
+                        state.stack_push(val);
+                        fun.push_insn(block, Insn::Jump(BranchEdge {
+                            target: join_block,
+                            args: state.as_args(self_param),
+                        }));
+                    }
+
+                    let ep_offset = get_arg(pc, 0).as_u32();
+                    let level = get_arg(pc, 1).as_u32();
+                    let branch_insn_idx = exit_state.insn_idx as u32;
+
+                    // If the block param is already a Proc (modified), read it from EP.
+                    // Otherwise, convert it to a Proc and store it to EP.
+                    let is_modified = fun.push_insn(block, Insn::IsBlockParamModified { level });
+
+                    let locals_count = state.locals.len();
+                    let stack_count = state.stack.len();
+                    let entry_args = state.as_args(self_param);
+
+                    // Set up branch and join blocks.
+                    let (modified_block, modified_self_param, mut modified_state, ..) =
+                    new_branch_block(&mut fun, branch_insn_idx, &exit_state, locals_count, stack_count);
+                    let (unmodified_block, unmodified_self_param, mut unmodified_state, unmodified_exit_id) =
+                    new_branch_block(&mut fun, branch_insn_idx, &exit_state, locals_count, stack_count);
+                    let join_block = insn_idx_to_block.get(&insn_idx).copied().unwrap_or_else(|| fun.new_block(insn_idx));
+
+                    fun.push_insn(block, Insn::IfTrue {
+                        val: is_modified,
+                        target: BranchEdge { target: modified_block, args: entry_args.clone() },
+                    });
+                    fun.push_insn(block, Insn::Jump(BranchEdge {
+                        target: unmodified_block,
+                        args: entry_args,
+                    }));
+
+                    // Push modified block: read Proc from EP.
+                    let modified_val = fun.push_insn(modified_block, Insn::GetLocal {
+                        ep_offset,
+                        level,
+                        use_sp: false,
+                        rest_param: false,
+                    });
+                    finish_getblockparam_branch(
+                        &mut fun,
+                        modified_block,
+                        modified_self_param,
+                        &mut modified_state,
+                        join_block,
+                        ep_offset,
+                        level,
+                        modified_val,
+                    );
+
+                    // Push unmodified block: convert block handler to Proc.
+                    let unmodified_val = fun.push_insn(unmodified_block, Insn::GetBlockParam {
+                        ep_offset,
+                        level,
+                        state: unmodified_exit_id,
+                    });
+                    finish_getblockparam_branch(
+                        &mut fun,
+                        unmodified_block,
+                        unmodified_self_param,
+                        &mut unmodified_state,
+                        join_block,
+                        ep_offset,
+                        level,
+                        unmodified_val,
+                    );
+
+                    // Continue compilation from the join block at the next instruction.
+                    queue.push_back((unmodified_state, join_block, insn_idx, local_inval));
+                    break;
+                }
                 YARVINSN_pop => { state.stack_pop()?; }
                 YARVINSN_dup => { state.stack_push(state.stack_top()?); }
                 YARVINSN_dupn => {
diff --git a/zjit/src/hir/opt_tests.rs b/zjit/src/hir/opt_tests.rs
index da24025010..0a42652993 100644
--- a/zjit/src/hir/opt_tests.rs
+++ b/zjit/src/hir/opt_tests.rs
@@ -3853,6 +3853,67 @@ mod hir_opt_tests {
     }
 
     #[test]
+    fn test_getblockparam() {
+        eval("
+            def test(&block) = block
+        ");
+        assert_snapshot!(hir_string("test"), @r"
+        fn test@<compiled>:2:
+        bb0():
+          EntryPoint interpreter
+          v1:BasicObject = LoadSelf
+          v2:BasicObject = GetLocal :block, l0, SP@4
+          Jump bb2(v1, v2)
+        bb1(v5:BasicObject, v6:BasicObject):
+          EntryPoint JIT(0)
+          Jump bb2(v5, v6)
+        bb2(v8:BasicObject, v9:BasicObject):
+          v13:CBool = IsBlockParamModified l0
+          IfTrue v13, bb3(v8, v9)
+          v24:BasicObject = GetBlockParam :block, l0, EP@3
+          Jump bb5(v8, v24, v24)
+        bb3(v14:BasicObject, v15:BasicObject):
+          v22:BasicObject = GetLocal :block, l0, EP@3
+          Jump bb5(v14, v22, v22)
+        bb5(v26:BasicObject, v27:BasicObject, v28:BasicObject):
+          CheckInterrupts
+          Return v28
+        ");
+    }
+
+    #[test]
+    fn test_getblockparam_nested_block() {
+        eval("
+            def test(&block)
+              proc do
+                block
+              end
+            end
+        ");
+        assert_snapshot!(hir_string_proc("test"), @r"
+        fn block in test@<compiled>:4:
+        bb0():
+          EntryPoint interpreter
+          v1:BasicObject = LoadSelf
+          Jump bb2(v1)
+        bb1(v4:BasicObject):
+          EntryPoint JIT(0)
+          Jump bb2(v4)
+        bb2(v6:BasicObject):
+          v10:CBool = IsBlockParamModified l1
+          IfTrue v10, bb3(v6)
+          v19:BasicObject = GetBlockParam :block, l1, EP@3
+          Jump bb5(v6, v19)
+        bb3(v11:BasicObject):
+          v17:BasicObject = GetLocal :block, l1, EP@3
+          Jump bb5(v11, v17)
+        bb5(v21:BasicObject, v22:BasicObject):
+          CheckInterrupts
+          Return v22
+        ");
+    }
+
+    #[test]
     fn test_getinstancevariable() {
         eval("
             def test = @foo
diff --git a/zjit/src/hir/tests.rs b/zjit/src/hir/tests.rs
index 3e28178273..44082ce908 100644
--- a/zjit/src/hir/tests.rs
+++ b/zjit/src/hir/tests.rs
@@ -2684,6 +2684,71 @@ pub mod hir_build_tests {
     }
 
     #[test]
+    fn test_getblockparam() {
+        eval("
+            def test(&block) = block
+        ");
+        assert_snapshot!(hir_string("test"), @r"
+        fn test@<compiled>:2:
+        bb0():
+          EntryPoint interpreter
+          v1:BasicObject = LoadSelf
+          v2:BasicObject = GetLocal :block, l0, SP@4
+          Jump bb2(v1, v2)
+        bb1(v5:BasicObject, v6:BasicObject):
+          EntryPoint JIT(0)
+          Jump bb2(v5, v6)
+        bb2(v8:BasicObject, v9:BasicObject):
+          v13:CBool = IsBlockParamModified l0
+          IfTrue v13, bb3(v8, v9)
+          Jump bb4(v8, v9)
+        bb3(v14:BasicObject, v15:BasicObject):
+          v22:BasicObject = GetLocal :block, l0, EP@3
+          Jump bb5(v14, v22, v22)
+        bb4(v17:BasicObject, v18:BasicObject):
+          v24:BasicObject = GetBlockParam :block, l0, EP@3
+          Jump bb5(v17, v24, v24)
+        bb5(v26:BasicObject, v27:BasicObject, v28:BasicObject):
+          CheckInterrupts
+          Return v28
+        ");
+    }
+
+    #[test]
+    fn test_getblockparam_nested_block() {
+        eval("
+            def test(&block)
+              proc do
+                block
+              end
+            end
+        ");
+        assert_snapshot!(hir_string_proc("test"), @r"
+        fn block in test@<compiled>:4:
+        bb0():
+          EntryPoint interpreter
+          v1:BasicObject = LoadSelf
+          Jump bb2(v1)
+        bb1(v4:BasicObject):
+          EntryPoint JIT(0)
+          Jump bb2(v4)
+        bb2(v6:BasicObject):
+          v10:CBool = IsBlockParamModified l1
+          IfTrue v10, bb3(v6)
+          Jump bb4(v6)
+        bb3(v11:BasicObject):
+          v17:BasicObject = GetLocal :block, l1, EP@3
+          Jump bb5(v11, v17)
+        bb4(v13:BasicObject):
+          v19:BasicObject = GetBlockParam :block, l1, EP@3
+          Jump bb5(v13, v19)
+        bb5(v21:BasicObject, v22:BasicObject):
+          CheckInterrupts
+          Return v22
+        ");
+    }
+
+    #[test]
     fn test_splatarray_mut() {
         eval("
             def test(a) = [*a]
diff --git a/zjit/src/stats.rs b/zjit/src/stats.rs
index cf100dcda2..556a1417a4 100644
--- a/zjit/src/stats.rs
+++ b/zjit/src/stats.rs
@@ -210,6 +210,7 @@ make_counters! {
         exit_stackoverflow,
         exit_block_param_proxy_modified,
         exit_block_param_proxy_not_iseq_or_ifunc,
+        exit_block_param_wb_required,
         exit_too_many_keyword_parameters,
     }
 
@@ -557,6 +558,7 @@ pub fn side_exit_counter(reason: crate::hir::SideExitReason) -> Counter {
         StackOverflow                 => exit_stackoverflow,
         BlockParamProxyModified       => exit_block_param_proxy_modified,
         BlockParamProxyNotIseqOrIfunc => exit_block_param_proxy_not_iseq_or_ifunc,
+        BlockParamWbRequired          => exit_block_param_wb_required,
         TooManyKeywordParameters      => exit_too_many_keyword_parameters,
         PatchPoint(Invariant::BOPRedefined { .. })
                                       => exit_patchpoint_bop_redefined,