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IBM Releases Compiler for Power4 and G5
davids-world.com writes "IBM offers its optimized XLC compiler not just for Intel CPUs, but also for its own G5 processor (article in German at Heise). Unlike gcc, it is optimized for the G5 and achieves a major boost in speed, as first results show. I guess we will have to compare the new benchmark data (once available) with the data we get with the optimized Intel compiler for Xeon. The compiler is available for download now."
Lest anyone forget, Apple beat Intel in real world benchmarks... so the PC fanboys cried that SPEC benchmarks are the real measurement to gague speed... (probably because the comparisons were much closer when conducted this way). When SPEC benchmarks were displayed, these same fanboys cried that Intel's compiler wasn't used (instead the same compiler between platforms). Apple replied that its fairer to normalize the compiler between platforms and that while Intel could have achieved higher results when their compiler was used, Apple could do the same. So, here is that compiler. When/if the G5 outperforms Intel's best, what will the fanboys rally cry be next?
And is there a particular reason why IBM couldn't apply their work towards gcc? So much for the whole open-source, contribute-to-the-community philosophy.
Maybe they just didn't feel like it. Maybe they just preferred working with their own code. IBM's contributed, a lot, it doesn't mean that they're now servants of the open source community.
Um, that's the point. IBM cooks up code to make the G5 look as fast as possible. Intel cooks up code to make the Xeon looks as fast as possible. Now compare. Fastest code/chip against the competition's fastest code/chip. The complaint in the past was that it was always the fastest code/chip of one side against a non-optimized code on the other side. Now we can have a fair shootout.
-T
If the parent or grandparent had glanced at the PDF, they too would have noticed that GCC compatibility was one of the major points covered. There are a few pages devoted to what currently is compatible with GCC as well as what's planned. My bet is that they've had their own optimized compiler around since they first fab-ed one of these, to use for test purposes.
It would be foolish to scrap all of the work they'd already done, as well as the performance achieved (double the performance of GCC in some cases, from the PDF). There is mention of this compiler supporting SuSe Enterprise Edition however, but not enough detail to tell if it can compile SuSe or just compile *on* SuSe.
If there is a plan to integrate stuff from this compiler into GCC, my guess is that GCC compatibility would be the first step. It would be very difficult to try to integrate the two if they have fundamentally different structures and no common ground to speak of, not to mention that fact that chip manufacturers invariably keep the true capabilities of their hardware more or less secret until launch time, and putting code into GCC from the beginning may tip their hand to others before they're ready to do so.
obDisclaimer: IANACompilerGuru
Do your homework. Apple modified the tests to reflect the actual shipping models, since they were running on prototype G5's. These issues have long been put to rest and Apple just updated their results the other day with actual shipping G5's. Get out of denial, x8 is not a religion, it's a processor for goodness sake.
Is the word "fanboy" used by anyone but fanboys?
The IBM compiler dis some wild instruction reordering which made the optimized compiled code really hard to understand, but somehow better fitted to the processor's pipeline structure. Fortunately the only thing that broke when I turned on the optimizer was the "marching ants" used for selection, and that was the result of some way-too-fancy-casting of Pattern pointers that fooled the optimizer. I suspect the IBM compilers will continue to reign if performance is the goal.