llvm dev - May 2009 - [LLVMdev] Using non-system compiler to build llvm and llvm-gcc front end

>> $ make -j15
>
> do you really have 15 CPUs?  If not, this will most
> likely just slow things down.
>
I have 8 CPUs. I started with -j8 and turned the knob up a bit. It
seemed to run faster, so I stuck with j15. I guess there might be some
context switching when threads are blocking on memory or IO. I could
be imagining the speedups though because of some sort of placebo
effect.

>> cc1: /pkg/build/llvm/llvm/lib/Analysis/ScalarEvolution.cpp:511:
>> bool<unnamed>::SCEVComplexityCompare::operator()(const
llvm::SCEV*,
>> const llvm::SCEV*) const: Assertion `0 && "Unknown SCEV
kind!"'
>> failed.
>> ../../llvm-gcc/libdecnumber/decNumber.c:5591: internal compiler error:
Aborted
>>
>> This is all with llvm and llvm-gcc source from svn.
>
> Since the SCEV code is changing rapidly at the moment, it may be that you
> had the bad luck to update to a broken revision.
Release 2.5 was giving me problems (see older posts on this thread). I
will see if updating my current revision helps.

> This looks like a clear bug in your system tools: note how it complains
> that a certain section is referenced by itself, and that this is a problem
> because it is being discarded, d'oh!  There's not much we can do
about this
> kind of thing.
OK, not quite sure what this means about my system tools. Is there
something I should be concerned about?

>> I have also tried installing with the llvm-gcc binary for RHEL4 (even
>> though I am running Centos 5). However, "make check" returned
a bunch
>> of unexpected failures.
>
> If you want llvm from svn, then you should use llvm-gcc from svn too.
Yes, I assumed so. I was just getting frustrated with not being able
to build the svn llvm-gcc, so I tried the binary.

> Ciao,
>
> Duncan.
>
Thanks for your help.

Hi,
> OK, not quite sure what this means about my system tools. Is there
> something I should be concerned about?
it seems that a bug in your system tools happens to be tickled by
LLVM.  We can't do much about the fact that your system doesn't
work properly, though if enough people see a problem we do sometimes
try to tweak LLVM so it avoids triggering the bug.  If you don't
have problems when building other programs then I guess there isn't
much to be concerned about!

Ciao,

Duncan.

OK, updated from svn (revision 71457) and got a successful
installation. For the record:

1) Installed gcc 4.3.2 in /pkg/bin/gcc-4.3.2 (to insulate it from the
system compiler)
2) Added /pkg/bin/gcc-4.3.2/bin to my PATH
3) Added /pkg/bin/gcc-4.3.2/lib and /pkg/bin/gcc-4.3.2/lib64 to
/etc/ld.so.conf and ran ldconfig
4) More or less followed README.LLVM:

Configure llvm:
$ ../configure --prefix=/pkg/bin/llvm

Build llvm:
$ make -j10

Configure llvm-gcc:
$ ../llvm-gcc/configure --prefix=/pkg/build/llvm-svn-updated/install
--program-prefix=llvm-
--enable-llvm=/pkg/build/llvm-svn-updated/llvm-obj
--enable-languages=c,c++

Build llvm-gcc:
$ make -j10

Install (run make install in object directories for both llvm and llvm-gcc)

"make check" in llvm-obj fails one of the tests unexpectedly if I
build with ENABLE_OPTIMIZED=1. It looks for some file in Debug and
doesn't find it (LLVMHello.so).

Thanks to Duncan, Anton, and Christian for helping me through this.

Scott