[LLVMdev] LLVM on OpenBSD

Edd Barrett vext01 at gmail.com
Wed Jun 18 06:08:46 PDT 2008

Holger Schurig wrote:
>> With 3.3.5 my first test took 5 times to produce a non "bus
>> error" build. There were no 'make cleans' in between.
>> What is going on?
> You mean you used your bsd-ports-provided gcc to compile LLVM and 
> you've got 4 times a bus-error during the build?  In this case, 
> it cannot be a LLVM problem.

Ok, to clarify,

I have tried the OpenBSD provided gcc-3.3.5 (which is considered the
least buggy version of gcc) and also with gcc-4.2 from ports.

Sometimes you get a clean build of llvm, sometimes you don't and instead
get a bus error.

> In the linux-community, people say that bus-error's are almost 
> always because of faulty hardware, e.g. problem with DRAM 
> timing, overheated CPU, power-supply that cannot provide enought 
> power during current surges, things like that.

That is one reason a bus error might occur, but my more common
understanding of a bus error is data not properly aligned with the byte
boundaries and/or out of range memory at the physical level.

The machine I am building on is my workstation which I use 9-4.30
mon-fri. I run all manner of apps without any problems, so if it were
bad hardware it would have shown itself by now surely.

As a test I got another developer to try on a different machine and he 
has the same problem. In another test he  also tried a more aggressive 
malloc.conf (a mechanism which causes malloc to do all sorts of 
randomisation and page filling to test for memory based bugs) and a 
completely different error was encountered:

SelectionDAG.cpp:2602: warning: converting of negative value
`-1' to `long long

Also we found that without specifying --enable-optimized, the 
optimisations were still present:

-O3 -fomit-frame-pointer -Woverloaded-virtual -pedantic
-Wall -W -Wwrite-strings -Wno-long-long -Wunused -Wno-unused-parameter



Best Regards


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