Fwd: Re: [LLVMdev] new IA64 backend
sabre at nondot.org
Sun Apr 10 15:48:23 PDT 2005
On Sun, 10 Apr 2005, Ricardo wrote:
> Does anybody know if there is some tool to convert from WHIRL to LLVM? maybe some project under
> development? a similar project?
I haven't heard of any such project, but it would be interesting if it
>> --- Duraid Madina <duraid at octopus.com.au> wrote:
>>> Date: Fri, 18 Mar 2005 12:45:54 +0900
>>> From: Duraid Madina <duraid at octopus.com.au>
>>> To: ahs3 at fc.hp.com, LLVM Developers Mailing List <llvmdev at cs.uiuc.edu>
>>> Subject: Re: [LLVMdev] new IA64 backend
>>> Al Stone wrote:
>>>> On Fri, 2005-03-18 at 05:04 +0900, Duraid Madina wrote:
>>>> Woo hoo! And There Was Much Rejoicing in IA64 Land :-).
>>> So we see here that Al has not yet run the test suite. ;-)
>>> Hmm. For those _not_ in IA64 land, here a few random things that might
>>> be interesting:
>>> - IA64, perhaps more than any other general purpose computing
>>> architecture, depends on something like LLVM for high performance.
>>> Whole-program optimization simply 'falls out' with LLVM, yet this is
>>> more or less the limit of what the Intel and HP compiles can do.
>>> Life-long optimization is particularly important on IA64, because
>>> there's only so much that the hardware can do to "help itself." It's
>>> true that some aspects of IA64 are completely orthogonal to things like
>>> out-of-order execution and one can imagine a monster "Itanium 4" (4 as
>>> in "Pentium 4" ;) ), but I personally hope that Intel doesn't go down
>>> that path - at least not until LLVM/IA64 has had a chance to conquer the
>>> world^W^W^Wprove itself in the field. Anyone who saw Intel's
>>> presentation at this year's ISSCC will probably hope so too; an Itanium
>>> 2/12MB @2.5GHz dissipating ~50W can be a frightfully powerful and fairly
>>> _efficient_ device for the 90nm node, but it only shines if you have the
>>> compiler support there.
>>> - IA64 specifies performance gathering abilities that are (to my
>>> knowledge, anyway) simply unparalleled. This might be interesting/useful
>>> for the LLVM-reoptimization folk.
>>> - JITs can be particularly quick on IA64. (No, really!) Register
>>> allocation is a piece of cake for example, and the IA64 machine model is
>>> quite simple.
>>> - The IA64 backend is a little odd in that it defines a register class
>>> for booleans, not just i64s and f64s.
>>> - IA64 users currently suffer from the lack of a solid,
>>> high-performance, easy-to-use open-source compiler. There are some good
>>> open-source compilers (ORC, IMPACT) but these break like twigs, and
>>> aren't really intended for production use. There's GCC which is
>>> _reasonably_ solid these days but the performance ranges from poor to
>>> underwhelming. I'm hoping that llvm-gcc will become an alternative for
>>> those who can't/won't use the Intel or HP compilers.
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu
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