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Strange behavior when asserting an output signal #494

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sam-falvo opened this issue Aug 29, 2020 · 1 comment
Closed

Strange behavior when asserting an output signal #494

sam-falvo opened this issue Aug 29, 2020 · 1 comment

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@sam-falvo
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I have some code which reads:

    xer_ov_o = dut.o.xer_ov.data
# ...
    comb += Assert(xer_ov_o == dut.i.xer_ov)

This assertion always fails when I run the formal check. However, if I change the above assertion to:

    comb += Assert(dut.o.xer_ov.data == dut.i.xer_ov)

then the assertion works! (If it helps, dut.o.xer_ov.data is a Signal(2).)

I'm not sure why this should be an issue; both dut.o.xer_ov.data and xer_ov_o should refer to the same Python object. Why should this be an issue?

Thanks.

@sam-falvo
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Disregard this issue; I had a small typo which got past two code reviews, but as Murphy's Law applies, I just found it after opening the ticket. :/

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