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Performance regression in Yosys 0.39 #4280

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whitequark opened this issue Mar 13, 2024 · 6 comments
Open

Performance regression in Yosys 0.39 #4280

whitequark opened this issue Mar 13, 2024 · 6 comments
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pending-verification This issue is pending verification and/or reproduction

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@whitequark
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whitequark commented Mar 13, 2024 •
edited

Version

0.39

On which OS did this happen?

Linux [I think this needs a "WebAssembly" choice; #4281]

Reproduction Steps

Run Glasgow Interface Explorer testcase glasgow.applet.interface.analyzer.test.AnalyzerAppletTestCase.test_build

Expected Behavior

Build passes timing.

Actual Behavior

Build does not pass timing since Yosys 0.39.
@whitequark whitequark added the pending-verification This issue is pending verification and/or reproduction label Mar 13, 2024
@whitequark whitequark mentioned this issue Mar 13, 2024
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@povik
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povik commented Mar 13, 2024

@whitequark Do we know v0.38 is fine?

@whitequark
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Yes, here is an equivalent build using Yosys 0.38+0

@whitequark
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I actually can't see any commit that should influence this, so maybe it was just a marginal test that worked for like a dozen or two Yosys versions but started failing now?

@povik
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povik commented Mar 13, 2024

I wonder too. I guess you can ask github to rerun the test, to see if it fails reliably?

@povik
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povik commented Mar 13, 2024

I guess you can ask github to rerun the test, to see if it fails reliably?

Ah, but it probably does fail reliably, because the synthesis is deterministic though chaotic. That's what you are getting at when you say it worked for a couple of Yosys versions...

@whitequark
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Yes.

whitequark added a commit to whitequark/glasgow that referenced this issue Mar 14, 2024
@whitequark
applet.interface.analyzer: restrict to revC0+.
04c1526 
After upgrading Yosys to 0.39, the applet stopped passing timing when
built for revA. This was reported against Yosys (YosysHQ/yosys#4280),
but as there don't seem to be any commits that could change synthesis
quality, it was likely just that the analyzer applet was marginal in
first place.

Since this is blocking all further development, the applet is now
restricted to revC0+.
@whitequark whitequark mentioned this issue Mar 14, 2024
Merged
github-merge-queue bot pushed a commit to GlasgowEmbedded/glasgow that referenced this issue Mar 14, 2024
@whitequark
applet.interface.analyzer: restrict to revC0+.
6f20482 
After upgrading Yosys to 0.39, the applet stopped passing timing when
built for revA. This was reported against Yosys (YosysHQ/yosys#4280),
but as there don't seem to be any commits that could change synthesis
quality, it was likely just that the analyzer applet was marginal in
first place.

Since this is blocking all further development, the applet is now
restricted to revC0+.
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