[LLVMdev] FYI: Phoronix GCC vs. LLVM-GCC benchmarks
David Greene
dag at cray.com
Tue Sep 15 08:35:57 PDT 2009
On Tuesday 15 September 2009 08:16, Olivier Meurant wrote:
> llvm-gcc -v
> Using built-in specs.
> Target: i686-pc-linux-gnu
>
> gcc -v
> Using built-in specs.
> Target: i486-linux-gnu
Different targets. It's no surprise 486 code would perform much worse than
i686 code. These compilers need to target the same architecture. Ideally the
Makefile would include appropriate -march/-mtune/whatever the gcc architecture
switch of the day is.
All test reports should also include switches passed to the compiler for each
run.
Right now this isn't a fair test. It's practically meaningless.
Remember, the goal here isn't to show how great LLVM is. It's to get an
honest assessment of where we are at. Phoronix did us a big favor. Getting
more details about his tests would help us even more.
For one thing, we (Cray) have a number of LLVM enhancements geared toward
Opteron that make a big difference in performance. I'm planning to contribute
much of this to our open source community. So there is definitely room for
improvement to LLVM. The biggest mistake we can make is to think we're the
best.
-Dave
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