small SPECIALIZE INLINE program taking gigabytes of memory to compile

I have a small program that is taking 1+ GB of memory to compile.

I've distilled the troublesome input down to the following:

{-# LANGUAGE BangPatterns #-}
import Data.Vector

knot :: Vector Double -> Int -> Double
knot vs k = vs ! idx0
  where
  !idx0 = abs k `mod` 16
{-# SPECIALIZE INLINE knot :: Vector Double -> Int -> Double #-}

noise :: Vector Double -> Int -> Double
noise vs k =
  knot vs k + knot vs k + knot vs k + knot vs k +
  knot vs k + knot vs k + knot vs k + knot vs k

Compiled with ghc -fprof-auto -prof -O2 -Wall. As far as I can tell, prof-auto, prof, and optimizations of at least -O1 are required to trigger it.

I'm using ghc-7.8.2 64bit for Windows. vector is version 0.10.9.1 (currently the latest on hackage). Same code worked fine on ghc 7.6.2.

Also worth noting: Even though the SPECIALIZE isn't needed, if you remove the SPECIALIZE or the INLINE the problem goes away. If you remove even one of the duplicated calls to knot vs k in the body of noise then the amount of memory required drops dramatically. Add more to increase the requirements. I've been able to push it up around 10 GB, but I don't have enough memory to test beyond that!

Thanks!

Trac metadata

Trac field	Value
Version	7.8.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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