GHC 6.8.1 on powerpc OS X 10.5

[Simon Marlow]

haskell at list.mightyreason.com wrote:
> There are two possible avenues to proceed along.  The first is to figure out
> from the crashing stage2 compiler what is going wrong to cause the segfault.

I bet it would be easier to find a smaller program that crashes.  Start 
from "hello world", or try the programs in testsuite/tests/ghc-regress/codeGen.

Cheers,
	Simon

> But I think this compiler was created in a broken state.  The "unknown
> relocation error 4" from the new 'ld' in 10.5 means it sees but cannot handle
> scattered PPC_RELOC_HI16 segments.  I am guessing that the stage2 compiler is
> linked wrong, which may be why it ends up with a bad address and the error:
>> Program received signal EXC_BAD_ACCESS, Could not access memory.
>> Reason: KERN_INVALID_ADDRESS at address: 0x4082000c
> 
> I do not think I know enough about compilers and linkers to write a good bug
> report to Apple about the fact that 'ld' seems (to me) to write scattered
> PPC_RELOC_HI16 segments which it cannot read and recognize.
> 
> Corey O'Conner : you are debugging ld as well.  Does the 'ld' code look broken
> to you (as detailed in my earlier reply to your message) ?
> 
> Cheers,
>   Chris
> 
> 
> Simon Marlow wrote:
>> The crash is in Haskell code, so the C backtrace is not to be trusted.
>> Actually in this case it looks correct up to schedule(), and the
>> uppermost frame is probably correct - the crash was really in
>> stg_ap_p_fast, but in between is garbage
>> (base_GHCziIOBase_noDuplicate_info).
>>
>> Looks like you're making good progress here, though!  Working backwards
>> from the crash and try to find out where the erroneous memory access
>> originated is the next step.  The wiki page has some useful tips:
>>
>> http://hackage.haskell.org/trac/ghc/wiki/DebuggingGhcCrashes
>>
>> Cheers,
>>     Simon
> 
>