Conflicting exceptions - False path and Multicycle Path

[harpv]

Hi,

I want to know what happens when there's a conflict between the false path and multicycle path exception definition. Which one takes precedence when there happens to be a path such that it's getting sensitized by both the fp and mcp timing exceptions?

Thanks,
Hari

 

[rca]

False path is more restrictive, and then this one has priority over the multicycle path exception.

Same idea for set_max_transition, you could not relax with this command, the tool will use the most constrainted value provided (or not) by the liberty or the constraint.

 

[rahul.achates]

Below is the order of precedence - Leftmost having higher priority.
SFP > MCP > SCP > SMT

 

[layowblue]

Thanks Rahul.
I think the synthesis tool always try to do a "easier" job in term of meeting the timing constraint. i.e. meeting the constraint of "false_path" is way easier than meeting the constraint of MCP or even SMT.
Is it correct?

Below is the order of precedence - Leftmost having higher priority.
SFP > MCP > SCP > SMT

 

[rahul.achates]

All constraints are having specific to a condition , one constraint can't replace another.

In Hardware , there are many signals and sometime it might be possible when you have apply more then one constraint on same signal , in that case, tools will look for order of precedence and final constraint will be applied having higher priority.

False path and MCP are not same.



Rahul