[rtl] refactor mask unit. #845

Job	Run time
Generate CI target for RTL elaborate	21s
Test elaborate (blastoise)	7m 52s
Test elaborate (physical_design_case_0)	8m 3s
Test elaborate (physical_design_case_1)	8m 19s
Test elaborate (physical_design_case_10)	8m 2s
Test elaborate (physical_design_case_11)	7m 58s
Test elaborate (physical_design_case_12)	8m 10s
Test elaborate (physical_design_case_13)	8m 29s
Test elaborate (physical_design_case_14)	8m 3s
Test elaborate (physical_design_case_15)	8m 0s
Test elaborate (physical_design_case_16)	8m 5s
Test elaborate (physical_design_case_17)	7m 56s
Test elaborate (physical_design_case_18)	8m 32s
Test elaborate (physical_design_case_19)	8m 2s
Test elaborate (physical_design_case_2)	8m 11s
Test elaborate (physical_design_case_20)	7m 54s
Test elaborate (physical_design_case_21)	7m 58s
Test elaborate (physical_design_case_22)	8m 0s
Test elaborate (physical_design_case_23)	2m 34s
Test elaborate (physical_design_case_24)	2m 39s
Test elaborate (physical_design_case_25)	2m 37s
Test elaborate (physical_design_case_26)	2m 38s
Test elaborate (physical_design_case_27)	2m 35s
Test elaborate (physical_design_case_28)	2m 40s
Test elaborate (physical_design_case_3)	2m 44s
Test elaborate (physical_design_case_4)	6s
Test elaborate (physical_design_case_5)	2m 39s
Test elaborate (physical_design_case_6)	2m 40s
Test elaborate (physical_design_case_7)	2m 47s
Test elaborate (physical_design_case_8)	2m 57s
Test elaborate (physical_design_case_9)	3m 21s
Test elaborate (rookidee)	2m 40s
Request physical design report	0s
	2h 53m 32s

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