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Stub code for JIT’ed code generated by compiler

before compilation


      wrapper
   +---------------------------------+
   |                                 |
---+-> entry:                        |
   |       jmp [next];               |
   |   next:                         |
   |       subl [rip + counter], 1;  |
   |       jne vm_entry;             |
   |       <exec_compile_and_patch>  |
   |       jmp entry;                |
   |                                 |
   +---------------------------------+

after compilation for self_class1


      wrapper                                class guard stub (1)
   +---------------------------------+     +--------------------------------------------+
   |                                 |     |                                            |
---+-> entry:                        |  +--+-> guard1:                                  |
   |       jmp [guard1]; ------------+-/   |       movq rdi, [r14 - (LFP_SELF)];        |
   |   next:                         |     |       class_guard(self_class1)  -----------+-----> exit
   |       subl [rip + counter], 1;  |     |   patch_point:                             |
   |       jne vm_entry;             |     |       jmp [jit_entry1];                    |
   |       <exec_compile_and_patch>  |     |         |                                  |
   |       jmp entry;                |     +---------+----------------------------------+
   |                                 |               |
   +---------------------------------+               |
                                                     |      JIT code for self_class
                                                     |   +---------------------------+
                                                     |   |                           |
                                                     +---+-> jit_entry1              |
                                                         |                           |
                                                         |     <jit_code>            |
                                                         |                           |
                                                         |                           |
                                                         +---------------------------+

after re-compilation for self_class1


      wrapper                                class guard stub (1)
   +---------------------------------+     +--------------------------------------------+
   |                                 |     |                                            |
---+-> entry:                        |  +--+-> guard1:                                  |
   |       jmp [guard1]; ------------+-/   |       movq rdi, [r14 - (LFP_SELF)];        |
   |   next:                         |     |       class_guard(self_class1)  -----------+-----> exit
   |       subl [rip + counter], 1;  |     |   patch_point:                             |
   |       jne vm_entry;             |     |       jmp [jit_entry2];                    |
   |       <exec_compile_and_patch>  |     |         |                                  |
   |       jmp entry;                |     +---------+----------------------------------+
   |                                 |               |
   +---------------------------------+               |
                                                     |      JIT code for self_class1
                                                     |   +---------------------------+
                                                     |   | +---------------------------+
                                                     |   | |                           |
                                                     +---+-+-> jit_entry2              |
                                                         | |                           |
                                                         | |     <jit_code>            |
                                                         | |                           |
                                                         +-|                           |
                                                           +---------------------------+

after compilation for self_class2


      wrapper                                class guard stub (1)                               class guard stub (2)
   +---------------------------------+     +--------------------------------------------+     +--------------------------------------------+
   |                                 |     |                                            |     |                                            |
---+-> entry:                        |  +--+-> guard1:                                  |   +-+-> guard2:                                  |
   |       jmp [guard1]; ------------+-/   |       movq rdi, [r14 - (LFP_SELF)];        |  /  |       movq rdi, [r14 - (LFP_SELF)];        |
   |   next:                         |     |       class_guard(self_class1)  -----------+-+   |       class_guard(self_class2)  -----------+-----> vm_entry
   |       subl [rip + counter], 1;  |     |   patch_point:                             |     |   patch_point:                             |
   |       jne vm_entry;             |     |       jmp [jit_entry1];                    |     |       jmp [jit_entry2];                    |
   |       <exec_compile_and_patch>  |     |         |                                  |     |         |                                  |
   |       jmp entry;                |     +---------+----------------------------------+     +---------+----------------------------------+
   |                                 |               |                                                  |
   +---------------------------------+               |                                                  |
                                                     |      JIT code for self_class1                    |      JIT code for self_class2
                                                     |   +---------------------------+                  |   +---------------------------+
                                                     |   |                           |                  |   |                           |
                                                     +---+-> jit_entry1:             |                  +---+-> jit_entry2:             |
                                                         |                           |                      |                           |
                                                         |     <jit_code>            |                      |     <jit_code>            |
                                                         |                           |                      |                           |
                                                         |                           |                      |                           |
                                                         +---------------------------+                      +---------------------------+