[rtl] refactor mask unit. #790

Job	Run time
Generate CI target for RTL elaborate	6s
Test elaborate (blastoise)	7m 19s
Test elaborate (physical_design_case_0)	7m 18s
Test elaborate (physical_design_case_1)	7m 21s
Test elaborate (physical_design_case_10)	7m 3s
Test elaborate (physical_design_case_11)	7m 18s
Test elaborate (physical_design_case_12)	7m 21s
Test elaborate (physical_design_case_13)	7m 34s
Test elaborate (physical_design_case_14)	7m 16s
Test elaborate (physical_design_case_15)	7m 22s
Test elaborate (physical_design_case_16)	7m 14s
Test elaborate (physical_design_case_17)	7m 10s
Test elaborate (physical_design_case_18)	7m 18s
Test elaborate (physical_design_case_19)	7m 20s
Test elaborate (physical_design_case_2)	7m 29s
Test elaborate (physical_design_case_20)	7m 17s
Test elaborate (physical_design_case_21)	2m 37s
Test elaborate (physical_design_case_22)	2m 42s
Test elaborate (physical_design_case_23)	2m 36s
Test elaborate (physical_design_case_24)	2m 40s
Test elaborate (physical_design_case_25)	2m 37s
Test elaborate (physical_design_case_26)	2m 39s
Test elaborate (physical_design_case_27)	2m 35s
Test elaborate (physical_design_case_28)	2m 38s
Test elaborate (physical_design_case_3)	2m 38s
Test elaborate (physical_design_case_4)	5s
Test elaborate (physical_design_case_5)	2m 40s
Test elaborate (physical_design_case_6)	2m 43s
Test elaborate (physical_design_case_7)	2m 45s
Test elaborate (physical_design_case_8)	2m 58s
Test elaborate (physical_design_case_9)	3m 22s
Test elaborate (rookidee)	2m 42s
Request physical design report	0s
	2h 30m 43s

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