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what is weight relating here in group_path synth command ?

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hariharan.gb

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Hi

In the synthesis command below:

DC Shell >> group_path -name <> -from <> -to <> -weight 2

what is this weight 2 represents in group path? can anyone explain exactly, what it does to our synthesis process ?

Thanks
Hariharan B
 

yx.yang

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When DC do optimization, it will give more effort(such as run time) to path group with bigger weight.
By default, all the path are given the same default weight value.
 

hariharan.gb

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Thanks Yang,

Can you please comment on the below as well.
If I am starting my synthesis, and say for example I have a critical path group violating with 3ns.
I have given set_path_group -name xxx -weight < 4 >

Correct me, if my understanding is wrong.
This means worst 4 path down from WNS will be given more importance and tool will try to fix these 4 paths as much as it can ( taking more time of tool).
If my understanding is correct - weight value varies from 0 -100, so 100 is the max path that is given to tool., we cant give more than that? correct ?

Thanks
Hariharan B
 

yx.yang

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The weight number "4" just set the optimization priority of the pathes. When issue the path_group command you need tell DC which pathes will give the weight (in you case is 4) value. You can use -from/-to option of this command to identify the pathes, on which you want to apply the weight value. Please "man group_path" in DC.
That is: "4" just represent the priority of the path group. In that path group you can have 1 timing path or 100000 timing pathes.
By the way, command is "group_path", not "set_path_group".
 

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