[GHC] #778: memory leak

[GHC]

#778: memory leak
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    Reporter:  guest     |        Owner:         
        Type:  bug       |       Status:  new    
    Priority:  normal    |    Milestone:  6.4.3  
   Component:  Compiler  |      Version:  6.4.2  
    Severity:  normal    |   Resolution:         
    Keywords:  memory    |   Difficulty:  Unknown
Architecture:  Unknown   |           Os:  Linux  
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Comment (by dcoutts at gentoo.org):

 The Gentoo GHC ebuild does partially use the users CFLAGS settings.

 It uses a filtered set of CLAGS for building the .c parts of GHC, ie the
 rts and an even more filtered set for building the .hs parts. -O2 and -O3
 are currently allowed for the .c files. -O3 is only allowed if the user is
 running the testing ~x86 / ~amd64 profiles. For 'stable' x86 and amd64
 profiles only -O2 is allowed for the .c files.

 For building the .hs files we only pass through abi flags to gcc, eg
 things like -mcpu=ultrasparc.

 So my suspicion in this case is that the bug is triggered by using -O3 in
 CFLAGS when emerging dev-lang/ghc. If so it will probably be due to the
 rts being compiled with gcc -O3. So either the rts is breaking some strict
 rule that gcc is relying on for correct optimisation (eg strict aliasing),
 or there is a mis-compilation bug in gcc-4.1.1.

 So my reccomendation to the original bug reporter is to try re-emerging
 with -O2 rather than -O3 in CFLAGS and see if the problem persists. It
 would be helpful to know if that does fix the problem as if it does we'll
 change the ghc ebuild to downgrade -O3 to -O2 to prevent this problem.
 BTW, in future it would be better to report this kind of bug in the Gentoo
 bugzilla first (so we can investigate if it's due to using an unstable
 build environment and/or settings).

 It might be interesting to try building the rts with gcc-4.1.1 and look to
 see if it warns about any strict aliasing issues.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/778>
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