r1caw ex ua6bqg
Member level 2
SPG flow: DC-topo and ICC STA results difference
Dear all!
I have two questions related to DC-topo to ICC BE flow.
I synthesized design in DC-topo with physical libraries (ref MW, tf, TLU+, libs etc) using "compile_ultra -spg" command. After synthesis has been done, I used ICC (with exactly same physical libraries as in DC) to source pre-placed design from DC-topo. I compared two pre-placed floorplans (from DC-topo and restored in ICC with "restore_spg_placement" command) - they are the same. But STA results are much worse in ICC, (slack is worse more than 2 times). Why I have this huge difference (Synopsys user guides told me about 10-20%, but not 200%)? Libraries are the same, floorplans with placed cells are the same.
I compared environments (variables, settings etc) from DC-topo and ICC using "write_environment -consistency" command and obtained two txt files (from DC-topo and from ICC) with environment variables and their values, etc. But comparing them (even using Meld or diff) is tedious. Maybe there is any DC/ICC command to automatically setup same environments to DC-topo/ICC? Or should I check only some keys variables from DC/ICC environment files to obtain STA consistency for restored pre-placed design within 10-20% in ICC?
Dear all!
I have two questions related to DC-topo to ICC BE flow.
I synthesized design in DC-topo with physical libraries (ref MW, tf, TLU+, libs etc) using "compile_ultra -spg" command. After synthesis has been done, I used ICC (with exactly same physical libraries as in DC) to source pre-placed design from DC-topo. I compared two pre-placed floorplans (from DC-topo and restored in ICC with "restore_spg_placement" command) - they are the same. But STA results are much worse in ICC, (slack is worse more than 2 times). Why I have this huge difference (Synopsys user guides told me about 10-20%, but not 200%)? Libraries are the same, floorplans with placed cells are the same.
I compared environments (variables, settings etc) from DC-topo and ICC using "write_environment -consistency" command and obtained two txt files (from DC-topo and from ICC) with environment variables and their values, etc. But comparing them (even using Meld or diff) is tedious. Maybe there is any DC/ICC command to automatically setup same environments to DC-topo/ICC? Or should I check only some keys variables from DC/ICC environment files to obtain STA consistency for restored pre-placed design within 10-20% in ICC?