icc中set_fix_hold的意思

NAME

set_fix_hold

Sets the fix_hold attribute on clocks in the current design.

status set_fix_holdclocks

clocks

Specifies the clocks on which to set the fix_hold attribute.

This command sets the fix_hold attribute on the specified clock objects in the current design. The fix_hold attribute informs optimization that hold time violations of the specified clocks should be fixed.
Fixing a hold violation requires slowing down data signals. Optimization fixes hold violations while fixing the design rules, but only if the maximum delay cost is not increased or if the set_cost_priority command is used to prioritize hold violations ahead of maximum delay cost. Optimization can violate setup and fix hold as long as the worst negative slack (WNS) is not made worse. Optimization might fix hold and violate setup on noncritical paths.
The report_clock -attributes command identifies the clocks that have the fix_hold attribute.
Use the remove_attribute command to remove the fix_hold attribute.Multicorner-Multimode Support

This command applies to the current scenario only.

The following command sets the fix_hold attribute on clock clk1.prompt> set_fix_hold clk1
The following command removes the fix_hold attribute from clock clk1.prompt> remove_attribute [get_clocks clk1] fix_hold

1. 固定hold time 这个概念是不对的。
2. hold time 是 foundry 库中cell 的时序参数。
3. set_fix_hold 设置这个属性即是告诉工具，要在PR时优化hold time。使之满足timing 要求。

谢谢回答

你们一般什么时候用这个命令?
我以前在做cts的时候用，感觉不好，工具似乎会放很多反相器和buff进去

我们一般都是sign off流程去fix hold，前提肯定是hold violation 数量还可以接受的情况下

嗯 我也是，前面的都不修hold滴！

学习了，

thanks for the response.where could I find man pages for ICC/ICC2 commands?

thanks too！