DevMeeting - 2021-08-10/11

[jackkoenig]

2021-08-10/11

Outreach

• [schuyler] No comments on YouTube videos worth addressing
  • [jiuyang] add the YouTube links to readme.
  • [jiuyang] upload slides.
• [jiuyang] find 2019 CCC Video(China).
• 2020 CCC slides are lost?

Discussion 1

• [schuyler] Cleanup CHIRRTL Emission Packagedir #1: Error on MPort Escaping When, Fix SyncReadMem.read(addr, en) to not do this #2064
  • Change SyncReadMem.read(addr, en) to not return the mport
  • [kevin] Just test what SiFive cores need here
  • [kevin] Remove CHIRRTL has been fundamentally broken for a long time and there are a lot of issues here related to enable inference, node vs. wire on read enable, etc.
  • [kevin] read enable in SRAM compiler: https://users.ece.cmu.edu/~koopman/ece548/hw/hw5/meml80.pdf
    _“When CSN is high, the memory goes to stand-by (power down) mode and no access to the memory can”
    **WARN: **_This datasheet might be from a very outdated 500nm technology from 1997. It would be nice if someone at SiFive could tell us if this is still relevant for 7nm.
  • [martin] The read enable in the data sheet is actually an output enable disabling the output driver to tri-state. This was needed in the old days for a bus based design. It might save some power, but most power saving in the datasheet is about chip select (CSN).
    • If we want to support OE then we should also call it output enable
    • The CSN also disable writes, not just reads
      • [kevin] the idea here was that the script invoking the SRAM compiler could take the conjunction of read and write enables to determine if the memory can be powered down
• [jiuyang] How to cite SMT backend?
  • My project depends on SMT, and I'm wondering how to cite Kevin’s job.
  • Cite the FIRRTL paper.
• [jiuyang] add emitter for optimized low firrtl firrtl#2304
  • Removed passes.Legalize
  • But this is used in barstools in https://github.com/ucb-bar/barstools/blob/cdd8af4153926f6bde583a4ebfbc87014cfee9ac/macros/src/main/scala/barstools/macros/MacroCompiler.scala#L786
  • How to fix it?
    • [kevin] Why does barstools depend on this?
    • [kevin] Kevin and Chick to dig into what’s going on here.
    • [kevin] I looked at it and for now I would just remove it, see if it breaks anything. It may never really have been necessary to begin with.
    • Doesn’t break anything, add in my PR:
      • fix for chipsalliance/firrtl#2095 chipsalliance/firrtl#1730 ucb-bar/barstools#101
        • ucb-bar/barstools@22423dc
      • Ask for merging 101
• [jiuyang] Work towards removing DependencyAPIMigration firrtl#2317

  • [schuyler] tl;dr: This is the plan to remove CircuitForm deprecations. This needs an owner.

    • [jiuyang] CircuitForm has been deprecated since 1.3, we should directly remove this.
      • However there is some work to figure out the dependency.
      • Will introduce API change in:

        • sealed abstract class FirrtlEmitter(form: CircuitForm)

        • case class CircuitState(

          circuit:     Circuit,
          
          
          form:        CircuitForm,
          
          
          annotations: AnnotationSeq,
          
          
          renames:     Option[RenameMap])
          
          
            Remove `form: CircuitForm` in 1.6
          

  • Sorry, I was out-of-office last week, and failed to work on this.

  • I can spare time on this branch this week, do I need to work on this?

  • [schuyler] I will do something about this.

• [jiuyang] prefer to using using system protoc and antlr4 in mill firrtl#2276
  • [schuyler] Ping Jack on Wednesday
• [jiuyang] Z3 CI debug #2057 ready for merging.
  • Ping Jack.
• [jiuyang] Speed up CI #2043
  • I’ll finish this PR this week.
  • Ping Jack.
• [jiuyang] remove DefRegInit, change DefReg API with option definition. #1944 ready for merging.
  • Ping jack.
• [jiuyang] Add CI to publish project to maven. cde#17 ready for merging.
  • Need chipsalliance sonatype account.
  • PLCT is applying gold member of chipsalliance from here, but seems to be ignored? :(
  • Ping Jack or Adam (Wednesday or Tuesday).
• [jiuyang] Add Diplomacy to Sandbox projects tac#76 asking help from jack on this.
  • Originally diplomacy from rocket-chip cannot use strict compile options(don’t check unconnected IO).
  • I kept all only LM and Node API for diplomacy, and can replace RC source directly via Split diplomacy into the standalone repository rocket-chip#2741
• [jiuyang] espresso
  • Test espresso with chisel3. Via https://github.com/chipsalliance/espresso/tree/z3-test
  • Working on a C++ version
    • a little bit slower, but much easier to maintain
    • Hopefully it will finish this month. Will release version 3.0
      • Deprecate a lot of APIs(lost codes) in 2.5
      • 3.0 will be a slim C++ rewrite.
  • Ask Jack for the license issue.

Discussion 2

• [schuyler] Cleanup CHIRRTL Emission Packagedir #1: Error on MPort Escaping When, Fix SyncReadMem.read(addr, en) to not do this #2064
• [kevin] would like to make some parts of the SMT backend public
  • [smt] make SMTLib + Btor2 emitters public objects firrtl#2326
  • add -E smt2 support (instead of in addition to -E experimental-smt2)
  • make SMTLibEmitter and Btor2Emitter public objects
  • make FirrtlToTransitionSystemPass a public object
• [kevin] can we use chiseltest for tests in the chisel repo?
  • would like to cut down on the number of testing frameworks
  • happy to add support for any missing features to chiseltest