[LLVMdev] Qualitative comparisons between Open64 and llvm
proljc at gmail.com
Tue Jul 6 23:35:55 PDT 2010
Hi, Arvind & Kun
"Generates crap code, has tons of bugs, the community is disorganized
selfish and driven by corporate bullshit"
2010/7/2 Ling Kun <erlv5241 at gmail.com>
> Hi, Arvind Sudarsanam:
> I know some of Open64. Above all, Open64 is designed for a high
> performance compiler. It is now supported by AMD, HP, ICT Chinese
> Academy of Science, etc. and has been ported to X86, Itanium, Loongson
> CPU etc.
> And to your questions
> 1, Open64 already have some main optimization phases, Inline for
> aggressive inline opt. LNO for loop opt, WOPT for machine independent
> opt( transform WHIRL to SSA , do opt, and transform back to WHIRL),
> CG for basic block control flow and target specific opt. You can add
> your passes depend on what your opt is.
> 2, Open64 has dump_* function and traces to get plenty of debugging
> information. It is very helpful for developers, According to my
> experience, WOPT phases is a little difficult to debug, because of
> SSA , alias computation,etc, however, nothing is difficult if you
> understand it :)
> 3,What do you mean by quality? According to SPEC CPU official websit,
> Open64(or pathscale) get better performance on some X86 and Itanium
> processors, you can find more at http://www.pathscale.com/node/18 .
> 4,Open64 has a maillist, you can get more help there.
> 5. Compare to LLVM and GCC, Open64's document is less. But code is
> the best way, and the comment gives many information. : )
> 6, while for retarget, Open64 use a targ_info directory for machine
> description, such as instruction, register, and scheduling
> information. While for multi core processors, Open64 already have
> openmp support.
> While for LLVM, I think other guys in this maillist can give you much
> more information : )
> Ling kun
> On Fri, Jul 2, 2010 at 2:25 AM, Arvind Sudarsanam
> <A.Sudarsanam at cputech.com> wrote:
> > Hi,
> > I have been working towards developing compiler optimization tools
> > targeting multi core processors while using LLVM IR as the starting
> > point and building on top of the analysis and optimization passes
> > available in the llvm source.
> > Recently, I looked into Open64 and its intermediate representation
> > WHIRL. Documentation for developers to use Open64 seems to be inadequate
> > (when compared to LLVM documentation). I am planning to download the
> > source and look into it.
> > I was wondering if anyone has worked with both LLVM and Open64 and has
> > some qualitative comparisons between the two. Maybe, in terms of (a)
> > Ease of developing new passes (2) Ease of debugging (3) Quality of
> > results (4) Support for developers (5) Documentation (6) Ability to
> > retarget towards multi core processors.
> > Thanks in advance
> > Sincerely
> > Arvind
> > CPU Technology
> > Software Engineer
> > _______________________________________________
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