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Derived BitPack instance introduces Dubious primitive instantiation warning #2386

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lmbollen opened this issue Jan 2, 2023 · 3 comments · May be fixed by #2397
Open

Derived BitPack instance introduces Dubious primitive instantiation warning #2386

lmbollen opened this issue Jan 2, 2023 · 3 comments · May be fixed by #2397
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@lmbollen
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lmbollen commented Jan 2, 2023

The implementation for derived BitPack instances produces the following warning when producing HDL:

GHC: Setting up GHC took: 0.167s
GHC: Compiling and loading modules took: 0.088s
Clash: Parsing and compiling primitives took 0.143s
GHC+Clash: Loading modules cumulatively took 0.534s
Clash: Compiling Example.Project.topEntity
Clash: Normalization took 0.069s
[WARNING] Dubious primitive instantiation for GHC.Num.Integer.integerToInt#: GHC.Num.Integer.integerToInt#: Integers are dynamically sized in simulation, but fixed-length after synthesis. Use carefully. (disable with -fclash-no-prim-warn)
Clash: Netlist generation took 0.001s
Clash: Compiling Example.Project.topEntity took 0.071s
Clash: Total compilation took 0.606s

Reproducer:

module Example.Project where

import Clash.Prelude

data AorB = A | B
  deriving (Generic, BitPack)

topEntity :: Bool -> AorB
topEntity = bitCoerce

GHC 9.0.2
Clash 1.6.4
@lmbollen lmbollen mentioned this issue Jan 2, 2023
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@leonschoorl
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It's caused by the unpack side of bitCoerce:

topEntity :: BitVector 1 -> AorB
topEntity = unpack

Gives the same error.

@leonschoorl
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leonschoorl commented Jan 2, 2023 •
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In the definition of unpack we effectively have:

sc = unpack @Int (x :: BitVector 64)

That generates the error seen here.

(Because unpack @Int uses fromIntegral

instance BitPack Int where
  [...]
  unpack = fromIntegral

)

@DigitalBrains1
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I think we should just add a prim for unpack @Int (but don't forget about -fclash-intwidth)

rowanG077 added a commit that referenced this issue Jan 4, 2023
@rowanG077
Unpack no longer warns
5738161 
FIXED: Clash no longer gives `Dubious primitive instantiation warning`
when using `unpack` [#2386](#2386).
@rowanG077 rowanG077 linked a pull request Jan 4, 2023 that will close this issue
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rowanG077 added a commit that referenced this issue Jan 4, 2023
@rowanG077
Unpack no longer warns
a07149a 
FIXED: Clash no longer gives `Dubious primitive instantiation warning`
when using `unpack` [#2386](#2386).
rowanG077 added a commit that referenced this issue Jan 4, 2023
@rowanG077
Unpack no longer warns
6bdbd9c 
FIXED: Clash no longer gives `Dubious primitive instantiation warning`
when using `unpack` [#2386](#2386).
rowanG077 added a commit that referenced this issue Jan 4, 2023
@rowanG077
Unpack no longer warns
4f99788 
FIXED: Clash no longer gives `Dubious primitive instantiation warning`
when using `unpack` [#2386](#2386).
rowanG077 added a commit that referenced this issue Jan 4, 2023
@rowanG077
Unpack no longer warns
06b8b75 
FIXED: Clash no longer gives `Dubious primitive instantiation warning`
when using `unpack` [#2386](#2386).
rowanG077 added a commit that referenced this issue Jan 4, 2023
@rowanG077
Unpack no longer warns
ec016d4 
FIXED: Clash no longer gives `Dubious primitive instantiation warning`
when using `unpack` [#2386](#2386).
@jvnknvlgl jvnknvlgl mentioned this issue Aug 2, 2024
Closed
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unpack no longer warns clash-lang/clash-compiler
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@leonschoorl @DigitalBrains1 @martijnbastiaan @lmbollen