Random test now available for the adder. Fails with a stack overflow …

[stevenmburns]

…on examples with 650 bits

[stevenmburns]

@mkorbel1 Is there a way to increase the stack size in Dart so that we don't hit a stack overflow error when working with 650 bit adders? Is there a lot of recursion inside the Dart simulator that might be causing this?

smburns@smburns-XPS-13-9370:~/ROHD/dart-pg/sklansky$ dart test test/sklansky_test.dart --plain-name 'adderRandom adder_650'
00:01 +0 -1: adderRandom adder_650 [E]                                                                                               
  Stack Overflow
  package:rohd/src/values/logic_value.dart 280:41  LogicValue.toString.<fn>
  dart:core                                        new _GrowableList.generate
  package:rohd/src/values/logic_value.dart 280:12  LogicValue.toString
  package:rohd/src/values/logic_value.dart 127:23  LogicValue.of.<fn>
  dart:core                                        new _GrowableList._ofEfficientLengthIterable
  package:rohd/src/modules/bus.dart 151:62         Swizzle._execute
  package:rohd/src/modules/bus.dart 143:9          new Swizzle.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/logic.dart 271:7                Logic._connect.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/modules/gates.dart 207:9        _TwoInputBitwiseGate._execute
  package:rohd/src/modules/gates.dart 194:7        _TwoInputBitwiseGate._setup.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/logic.dart 271:7                Logic._connect.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/modules/bus.dart 85:14          BusSubset._execute
  package:rohd/src/modules/bus.dart 76:7           BusSubset._setup.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/logic.dart 271:7                Logic._connect.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/logic.dart 271:7                Logic._connect.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/modules/bus.dart 152:9          Swizzle._execute
  package:rohd/src/modules/bus.dart 143:9          new Swizzle.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/logic.dart 271:7                Logic._connect.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/modules/gates.dart 207:9        _TwoInputBitwiseGate._execute
  package:rohd/src/modules/gates.dart 194:7        _TwoInputBitwiseGate._setup.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/logic.dart 271:7                Logic._connect.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/modules/bus.dart 85:14          BusSubset._execute
  package:rohd/src/modules/bus.dart 76:7           BusSubset._setup.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/logic.dart 271:7                Logic._connect.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/logic.dart 271:7                Logic._connect.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/modules/bus.dart 152:9          Swizzle._execute
  package:rohd/src/modules/bus.dart 143:9          new Swizzle.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/logic.dart 271:7                Logic._connect.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  .                                                ...
  .                                                ...
  package:rohd/src/modules/gates.dart 194:7        _TwoInputBitwiseGate._setup.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/logic.dart 271:7                Logic._connect.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/modules/bus.dart 85:14          BusSubset._execute
  package:rohd/src/modules/bus.dart 76:7           BusSubset._setup.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/logic.dart 271:7                Logic._connect.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  package:rohd/src/logic.dart 271:7                Logic._connect.<fn>
  package:rohd/src/logic.dart 446:25               Logic.put
  test/sklansky_test.dart 145:11                   testAdderRandom.<fn>
  

To run this test again: dart test test/sklansky_test.dart -p vm --plain-name 'adderRandom adder_650'
adder: 3304706197836812759313325637912508255537535214315586495879430796578571070866797883083557183765831691174296207740223668164073333337864819475213625961188542909505648205287396707218007041970145732200 2483203407525067014820450385970580323274998194533180467780631588296854441716914817004833724537803739030759912953399505954458672186486717092210015017386647456960309740172996485603211241546754820001 1115970412916751870245216299645990262121867417426241594746969246546567741362027056306336189514647116831726395690262501032386771889663088057212915787179643037695915398915481883936355110656378285577 1115970412916751870245216299645990262121867417426241594746969246546567741362027056306336189514647116831726395690262501032386771889663088057212915787179643037695915398915481883936355110656378285577
...

[mkorbel1]

I haven't seen this before. From the stack trace, I think the chain of Logic.put is the signal propagating through the design. I don't know of a way to increase the stack size but I haven't tried before. I'll experiment a bit with this.

[mkorbel1]

I don't think there's an easy way to just increase the stack size in Dart, though it is apparently possible (I think down this route: https://unix.stackexchange.com/questions/127602/default-stack-size-for-pthreads/127615#127615).

However, I have some paths to go down that I think should make this much harder to hit while also improving simulation performance. I also might have a way to make it so you'll never hit this. I'll keep you updated!

I think this only would affect really long combinational chains of logic.

[stevenmburns]

I think that is right. However you might specify a really long combinational chain expecting that synthesis will fix it up. There is a 512-bit priority mux in OpenROAD’s version of Black Parrot that is specified in a linear way like this (the output of sv2v). You might also want to use an inefficient but easy to understand design as a reference in a miter simulation with a block you care about. From: Max Korbel ***@***.***> Sent: Tuesday, November 8, 2022 8:53 AM To: stevenmburns/rohd_sklansky ***@***.***> Cc: Burns, Steven M ***@***.***>; Author ***@***.***> Subject: Re: [stevenmburns/rohd_sklansky] Random test now available for the adder. Fails with a stack overflow … (PR #6) I don't think there's an easy way to just increase the stack size in Dart, though it is apparently possible (I think down this route: https://unix.stackexchange.com/questions/127602/default-stack-size-for-pthreads/127615#127615). However, I have some paths to go down that I think should make this much harder to hit while also improving simulation performance. I also might have a way to make it so you'll never hit this. I'll keep you updated! I think this only would affect really long combinational chains of logic. — Reply to this email directly, view it on GitHub<#6 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AALRI7V34EOOOHG2UTPIM6TWHKAOHANCNFSM6AAAAAARZSLHFQ>. You are receiving this because you authored the thread.Message ID: ***@***.******@***.***>>

[mkorbel1]

@stevenmburns I didn't fully fix the issue yet, but the changes in this PR should significantly mitigate the issue and allow longer chains of combinational logic. A full fix requires a bigger set of changes.
intel/rohd#199

[mkorbel1]

@stevenmburns ROHD v0.4.1 was just released, including the mitigation that helps with this issue
https://pub.dev/packages/rohd/changelog