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  • Glasgow Haskell CompilerGlasgow Haskell Compiler
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  • #4856
Closed
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Issue created Dec 21, 2010 by Manuel M T Chakravarty@mchakravartyReporter

Performance regression in the type checker regression for GADTs and type families

The GHC 7.0.2 RC1 shows poor performance when compiling Data.Array.Accelerate. In particular, to type check a particular module, GHC 7.02 takes several minutes, while GHC's resident memory grows to 350MB. In contrast, GHC 6.12.3 compiles the same module in a few seconds.

How to reproduce the problem:

  1. Download the latest version of Data.Array.Accelerate with darcs from http://code.haskell.org/accelerate/
  2. Change directory to the new accelerate darcs repo.
  3. Invoke GHCi as ghci -Iinclude.
  4. Issue the GHCi command: :l Data/Array/Accelerate/Smart.hs

You will notice that Data.Arra.Accelerate.Array.Sugar, which is heavy in type classes and type families, already requires a noticeable time to compile — this is already a performance regression from 6.12.3. The module Data.Array.Accelerate.Smart requires an even much longer time to compile.

Trac metadata
Trac field Value
Version 7.0.1
Type Bug
TypeOfFailure ValidProgramRejected
Priority normal
Resolution Unresolved
Component Compiler (Type checker)
Test case
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