[Haskell-cafe] segmentation fault with ghc-6.10.4 on linux-x86_x64

[Thomas Schilling]

This wiki page has some tips on how to debug compiled code.
http://hackage.haskell.org/trac/ghc/wiki/Debugging/CompiledCode

It mentions some parts specific to debugging the GHC code generator,
so some parts may not be relevant to your case.

HTH

On 2 March 2010 10:29, Wim Vanderbauwhede <wim.vanderbauwhede at gmail.com> wrote:
> Hello,
>
> I'm writing a compiler and it segfaults when compiled with  ghc-6.10.4
> on linux-x86_x64.
> It runs fine when compiled with ghc-6.10.4 on Mac OS X 10.5 (64-bit
> Intel) and with ghc-6.8.2 on Mac OS X 10.4 (32-bit PPC).
> I use the Haskell platform, the ghc -v output is
>
> Glasgow Haskell Compiler, Version 6.10.4, for Haskell 98, stage 2
> booted by GHC version 6.8.2
> Using package config file: /usr/local/lib/ghc-6.10.4/./package.conf
> Using package config file: /users/wim/.ghc/x86_64-linux-6.10.4/package.conf
> hiding package base-3.0.3.1 to avoid conflict with later version base-4.1.0.0
> hiding package network-2.2.1.2 to avoid conflict with later version
> network-2.2.1.4
> hiding package time-1.1.2.4 to avoid conflict with later version time-1.1.4
> wired-in package ghc-prim mapped to ghc-prim-0.1.0.0
> wired-in package integer mapped to integer-0.1.0.1
> wired-in package base mapped to base-4.1.0.0
> wired-in package rts mapped to rts-1.0
> wired-in package haskell98 mapped to haskell98-1.0.1.0
> wired-in package syb mapped to syb-0.1.0.1
> wired-in package template-haskell mapped to template-haskell-2.3.0.1
> wired-in package dph-seq mapped to dph-seq-0.3
> wired-in package dph-par mapped to dph-par-0.3
>
>
>
> The offending code is (simplified)
>
>     mapM emit (sc_args sc)
>
> with
>
>    sc::ServiceCall
>    data ServiceCall = MkServiceCall { sc_args::[Expr], ... }
>    data Expr = PureE (PString String) | ...
>
> and emit defined via a type class EmitG:
>
>    emitExpr (PureE e) = emit e
>   instance EmitG Expr where emit = emitExpr
>
>    emitPureExpr (PString s) = return $ show s
>    instance EmitG PureExpr where emit = emitPureExpr
>
> So it actually maps "show" over a list of strings.
>
> The compiler parses a test program, the segfault occurs when emitting
> code for lines like
>  ImgBlock() img1 = img.in("img.raw");
> (a "service call" in my language)
> Replacing the string by a number of any other type of the AST makes no
> difference.
>
> It looks like a bug in ghc's memory allocation. Any suggestions on how
> to debug this?
>
>
> Thanks!
>
> Wim
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