Rewrite IncompressibleRegions (may not look good)

.cpp

void BarrierSetAssembler::nmethod_entry_barrier(MacroAssembler* masm, Label* slow_path, Label* continuation, Label* guard) {
  BarrierSetNMethod* bs_nm = BarrierSet::barrier_set()->barrier_set_nmethod();

  if (bs_nm == NULL) {
    return;
  }

  // Assembler::IncompressibleRegion ir(masm);  // Remove our IncompressibleRegion to rewrite it to an instruction-level granularity

  Label local_guard;
  NMethodPatchingType patching_type = nmethod_patching_type();

  if (slow_path == NULL) {
    guard = &local_guard;

    // ...
    __ align(4);
  }

  __ lwu(t0, *guard);

  switch (patching_type) {
    case NMethodPatchingType::conc_data_patch:
      // ...
      __ membar(MacroAssembler::LoadLoad);
    case NMethodPatchingType::stw_instruction_and_data_patch:
      {
        // ...
        // ...
        // ...
        // ...
        // ...
        // ...
        // ...
        Address thread_disarmed_addr(xthread, in_bytes(bs_nm->thread_disarmed_offset()));
        __ lwu(t1, thread_disarmed_addr);
        break;
      }
    case NMethodPatchingType::conc_instruction_and_data_patch:
      {
        // ...
        // ...
        // ...
        // ...
        // ...
        // ...
        // ...
        // ...
        __ la(t1, ExternalAddress((address)&_patching_epoch));     // We have to make things inside 'la' incompressible, transitive
        // ...
        __ _srli(ra, t0, 32);         // Use '_' to prevent compressions
        __ _orr(t1, t1, ra);          // Use '_' to prevent compressions
        // ...
        __ lwu(t1, t1);
        // ...
        __ _slli(t1, t1, 32);         // Use '_' to prevent compressions
        __ _orr(t0, t0, t1);          // Use '_' to prevent compressions
        // ...
        Address thread_disarmed_and_epoch_addr(xthread, in_bytes(bs_nm->thread_disarmed_offset()));
        __ _ld(t1, thread_disarmed_and_epoch_addr);  // Note that we have to add a _ld(Register, Address) here, because we only have the _ld(Register, Register, int32_t offset) in the code base; maybe we have to add a _ld(Register, address) as well...
        break;
      }
    default:
      ShouldNotReachHere();
  }

  if (slow_path == NULL) {
    Label skip_barrier;
    __ _beq(t0, t1, skip_barrier);    // Use '_' to prevent compressions

    int32_t offset = 0;
    __ movptr_with_offset(t0, StubRoutines::riscv::method_entry_barrier(), offset);  // We have to make what inside the movptr_with_offset incompressible...
    __ _jalr(ra, t0, offset);         // Use '_' to prevent compressions
    __ _j(skip_barrier);              // Use '_' to prevent compressions

    __ bind(local_guard);

    MacroAssembler::assert_alignment(__ pc());
    __ emit_int32(0); // nmethod guard value. Skipped over in common case.
    __ bind(skip_barrier);
  } else {
    __ _beq(t0, t1, *continuation);    // Use '_' to prevent compressions
    __ _j(*slow_path);                 // Use '_' to prevent compressions
    __ bind(*continuation);
  }
}