encounter工具对net set_dont_touch

lingshaner

陈斑竹：
        请教一个问题，用encounter做layout工具，遇到 set_dont_touch [get_nets U1/U2/N1]
如果有这样的一条约束，encounter是只dont_touch U1/U2/N1 这个阶层的net，还是U1/N1也
被dont touch呢？
        ICC里面dont touch的属性是不能穿过阶层的，不知道encounter的规则是什么？

陈涛

所有层
你肯定“ICC里面dont touch的属性是不能穿过阶层的”？

lingshaner

是的，net肯定不能，这是我在synopsys的solvnet上当下来的，你可以看看：
Question:

I have a net in my design that I want to preserve during place_opt/route_opt.
I use set_dont_touch to define a dont_touch attribute on this net. But as this net is going to different logical hierarchies, optimization is adding buffers on the segments of the net where I did not define dont_touch.

Doesn't dont_touch propagate through the hierarchy? What I can do to preseve such nets?

Answer:

dont_touch doesn't propagate through the hierarchies. So if your design has a net going inside different logical hierarchies, it will have different hierarchical segments (each segment with a different full name).

In such cases, if you define dont_touch on a single segment, it will not propagate through the logical hierarchy, and only that single net segment will be dont_touch. Optimization is free to buffer other segments.

If you want to prevent this, you need to define set_dont_touch on all those segments.

However, it may be difficult to find all such segments. So here are few other options you may want to consider:

陈涛

謝謝！
這個以前還真沒有注意到

AveryYoung

楼主，你好，请教一个问题；
在edi中，有一个设计，需要给某个input信号加上一个buffer，增加驱动能力，从命令ecoaddrepeater来看，我不知道要如何能够找到这个input pin所在的net名字。求助一下，怎么找到这个net的名字？
还有这个命令是要在route之后报了网表中去找net吗？

漠北

回复 5# AveryYoung


    这个诉求，现成的命令应该是没有，但是可以写脚本抓出来


foreach_in_collection a [get_pins -hier -filter "full_name=~ **你需要查的input的pin名字关键字*"]
{
set pinName [get_attribute [get_pins $a] full_name]
set b [get_attribute [all_fanout -from [get_pins $pinName] -level 1 -flat -only_cells] full_name ]
echo "$b" >> ../data/aa
}