Re: Added LLVM 1.2 to nightly SPEC comparison runs

[Diego Novillo <dnovillo at redhat dot com>]

On Thu, 2004-04-08 at 11:18, Chris Lattner wrote:

> How did you build LLVM?
>
$ ../llvm/configure --with-llvmgccdir=/home/cygnus/dnovillo/llvm/1.2/cfrontend/x86/llvm-gcc --enable-spec2000=/notnfs/dnovillo/spec2000 --enable-optimized --prefix=/home/cygnus/dnovillo/llvm/1.2

>   By default it compiles in debug mode and
> extensive assertion checking that are useful for development (think
> "checking enabled"++).  If you build the tree with 'make
> ENABLE_OPTIMIZED=1' you should get the binaries in the llvm/tools/Release
> instead of the llvm/tools/Debug directory.  It is also worth checking to
> make sure that the C front-end you are using is not compiled in debug
> mode.
> 
Dunno.  I used the binaries you have in your web page.  I would presume
you build releases with --disable-checking.

> The other, perhaps more important, thing to remember is that you are
> asking LLVM to compile the program *twice*: first with LLVM (optimizing it
> and emitting a C file), then with GCC to compile the gigantic C file for
> the whole program to native code.  These C files are often pretty big
> (e.g., 966077 LOC and 42MB for 176.gcc), so that adds a substantial time
> penalty to the compilation process.
> 
Ah, good point.  There isn't an easy way to compare compile times, then.

> If you're rather wait until 1.3 is out, that's
> also fine, it will probably be out in a couple of months or so.
> 
I'd rather track released versions of other compilers.  It makes
comparison easier.  Will 1.3 have the -Wl,-native-cbe patch that I had
to apply to run SPEC?

> Do you have any idea why gcc, crafty, perlbmk and vortex are failing for
> you?  They work fine for us, so I'd like to know if there is some sort of
> bug that is triggering for you but not us or something.
> 
crafty miscompares.  Check the SPEC log file at
http://people.redhat.com/dnovillo/spec2000/baseline-llvm12/log/20040407/

Perhaps I need some portability flags for llvm.  What do you folks have
in your spec.cfg?

> Do you have any code size numbers?  Our inliner is currently tuned to be
> pretty conservative, it would be interesting to see how size compares.
> 
Ah, no.  Those are not gathered anymore, sorry.


> Is there any interest in compiling the output of LLVM with tree-ssa?
>
Sure.  You could target llvm to mainline after the merge.


> Also, can you change "gcc version 3.4-llvm 20030924 (experimental)" to
> "LLVM 1.2"?
> 
Well, yes, but the script just uses whatever 'llvmgcc --version' says. 
The page is autogenerated, so it would be overwritten the next time it's
updated.


Diego.