Author: Robert Hyatt
Date: 13:20:39 10/02/02
Go up one level in this thread
On October 02, 2002 at 15:13:32, Vincent Diepeveen wrote: >On October 01, 2002 at 22:43:58, Robert Hyatt wrote: > >>On October 01, 2002 at 09:43:00, Vincent Diepeveen wrote: >> >>>On September 30, 2002 at 12:13:44, Robert Hyatt wrote: >>> >>>>On September 30, 2002 at 00:09:28, Jeremiah Penery wrote: >>>> >>>>>On September 29, 2002 at 23:31:36, Robert Hyatt wrote: >>>>> >>>>>>I don't know what this means. I have several dozen programs (Crafty >>>>>>is only one) that we have run using intel's compiler and gcc, and in >>>>>>_every_ case, Intel's compiler is faster. On P2's, on P3's and on >>>>>>P4's... Of course I wouldn't use intel's compiler for an AMD chip, >>>>>>why would they want to optimize for a competitor's chip??? >>>>> >>>>>They don't have to optimize specifically for the competitor's chip, as Intel >>>>>compiler still produces probably the fastest binaries for AMD machines. Any >>>>>general optimizations (P2, P3, and even P4 optimizations (excluding SSE2 stuff >>>>>or whatever)) are just as helpful for AMD processors as they are for Intel ones. >>>> >>>> >>>>Maybe or maybe not. AMD's pipeline is different, and there are subtle >>>>differences in instruction choices, that can make a difference in speed. I >>>>don't see why the Intel compiler guys would bother studying AMD at all... >>> >>>I bet 50% of their time goes into studying what is faster for P4 than for K7 :) >> >> >>I'd bet they don't. Optimizing for a specific processor family is tough. >> >>Trying to optimize for one while producing code that does worse on another >>processor is a _real_ can of worms. I don't think anyone would waste that >>kind of time. > >I am very sure they will. We talk about billions being at stake here. >It is completely naive to suppose they do not study the K7. What does it feel like to be "the world's foremost authority on everything?" I am sure Intel has studied AMD chips. I am also sure that the _compiler_ guys are _not_ paying any attention to it, because there is no point to doing so. Have you written a compiler? I have. Have you written an optimizer? I have. Do you know what you are talking about here? I do. Don't make things up. Get real answers. Just like the quad 1.6ghz machines that you claim do not exist but which dell is shipping. I explained that to you a couple of weeks ago. I can't find that quad 2.2 I saw the output from, as that is what I was looking for. But I found several quads in the 1.4-1.6 range. > It is very >good deal to pay a few guys fulltime in order to sell for a couple of >billions more. Because if YOUR compiler, which without question >is doing great at specint tests, is going to let their processor look >better then you sell a couple of billions less. Again, the compiler guys are more interested in making code run faster on their processor. Not in making it run _slower_ on an AMD processor. Nothing forces _anybody_ to use the intel compiler to produce SPEC numbers. If their compiler is worse than MSVC then everyone would use MSVC. Intel would have wasted hundreds of thousands of dollars on the compiler development, and gotten _nothing_ from it. In reality, they just try to make the code run as fast as possible on their chips and to heck with everyone else... > >Do you want to take the risk of a couple of billions? > >Say 50 billion dollar? make up whatever number you want. It doesn't change the basic facts I gave you above. Wave your hands all you want, if it makes you feel better, although it won't make your ramblings true.
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