Certain annotations are not getting deleted by SFC, resulting in compilation failures when running MFC

[joonho3020]

Background Work

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Feature Description

DontTouchAnnotations are not getting deleted after the SFC pass, which results in MFC errors. This is because MFC will try to perform passes correlated to DontTouchAnnotations but the related variables may be missing(SFC could have renamed it or sth).

Currently, we are addressing this by deleting all the corresponding annotations by using jq inside common.mk (#1239).
In the long term, we want a cleaner way of doing this (e.g., fix the SFC to delete the annotations after they are used).

Another related issue is that MFC cannot compile designs containing Fixed & Interval types. At the moment, we are using SFC to compile CHIRRTL into LowFIRRTL & MFC to compile LowFIRRTL to Verilog when we find Fixed types inside the design (we perform grep Fixed inside common.mk). For the SFC + MFC compilation steps to work more elegantly, we need to rewrite Fixed types (and Interval types).

Motivating Example

Look at #1239.