Timber Wolf 7 0 Placement n Perform Timber

Timber. Wolf 7. 0 Placement n Perform Timber. Wolf placement § Based on the given standard cell placement § Initial HPBB wirelength = 23 Practical Problems in VLSI Physical Design Timber. Wolf Placement (1/16)

First Swap node b and e § We shift node h: on the shorter side of the receiving row § Node b included in nets {n 3, n 9}, and e in {n 1, n 7} Practical Problems in VLSI Physical Design Timber. Wolf Placement (2/16)

Computing ΔW n ΔW = wirelength change from swap Practical Problems in VLSI Physical Design Timber. Wolf Placement (3/16)

Estimating ΔWs n ΔWs = wirelength change from shifting § h is shifted and included in n 4 = {d, h, i} and n 7 ={c, e, f, h, n} § h is on the right boundary of n 4: gradient(h)++ § h is not on any boundary of n 7: no further change on gradient(h) Practical Problems in VLSI Physical Design Timber. Wolf Placement (4/16)

Estimating ΔWs (cont) Practical Problems in VLSI Physical Design Timber. Wolf Placement (5/16)

Accuracy of ΔWs Estimation n How accurate is ΔWs estimation? § Node h is included in n 4 = {d, h, i} and n 7 ={c, e, f, h, n} § Real change is also 1: accurate estimation Practical Problems in VLSI Physical Design Timber. Wolf Placement (6/16)

Estimation Model B n Based on piecewise linear graph § Shifting h causes the wirelength of n 4 to increase by 1 (19 to 20) and no change on n 7 (stay at 28) Practical Problems in VLSI Physical Design Timber. Wolf Placement (7/16)

Second Swap node m and o § We shift node d and g: on the shorter side of the receiving row § Node m included in nets {n 5, n 9}, and o in {n 2, n 10} Practical Problems in VLSI Physical Design Timber. Wolf Placement (8/16)

Computing ΔW n ΔW = wirelength change from swap Practical Problems in VLSI Physical Design Timber. Wolf Placement (9/16)

Estimating ΔWs n Cell d and g are shifted § d is included in n 4 = {d, h, i}, n 6 ={d, k, j}, and n 8 ={d, l} § d is on the right boundary of n 6 and n 8 § So, gradient(d) = 2 Practical Problems in VLSI Physical Design Timber. Wolf Placement (10/16)

Estimating ΔWs (cont) n Cell d and g are shifted § g is included in n 1 = {a, e, g}, and n 9 ={b, g, i, m} § g is on the right boundary of n 1 and n 9 § So, gradient(g) = 2 Practical Problems in VLSI Physical Design Timber. Wolf Placement (11/16)

Estimating ΔWs (cont) Practical Problems in VLSI Physical Design Timber. Wolf Placement (12/16)

Third Swap node k and m § We shift node c: on the shorter side of the receiving row § Node k included in nets {n 3, n 6 , n 10}, and m in {n 5, n 9} Practical Problems in VLSI Physical Design Timber. Wolf Placement (13/16)

Computing ΔW n ΔW = wirelength change from swap Practical Problems in VLSI Physical Design Timber. Wolf Placement (14/16)

Estimating ΔWs n Cell c is shifted § c is included in n 3 = {b, c, k, n} and n 7 ={c, e, f, h, n} § c is on the left boundary of n 3 § So, gradient(c) = − 1 Practical Problems in VLSI Physical Design Timber. Wolf Placement (15/16)

Estimating ΔWs (cont) Practical Problems in VLSI Physical Design Timber. Wolf Placement (16/16)