Date: Mon, 10 Jan 2005 14:26:06 -0500 From: Jeremy Tregunna <jtregunna@blurgle.ca> To: "William H. Magill" <magill@mcgillsociety.org> Cc: David Gilbert <dgilbert@dclg.ca> Subject: Re: processor type. Message-ID: <7944CAFC-633D-11D9-8BEE-0003930A1676@blurgle.ca> In-Reply-To: <C81C63C4-6321-11D9-B8BD-000393768D2C@mcgillsociety.org> References: <16866.32790.398095.651691@canoe.dclg.ca> <C81C63C4-6321-11D9-B8BD-000393768D2C@mcgillsociety.org>
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On 10-Jan-05, at 11:07 AM, William H. Magill wrote: <snip> > However, I understand that the GCC compiler picked up (some?many?all) > the Alpha optimization enhancements offered by Compaq shortly before > the Intel/HP deal. If this is the case, it doesn't do them very well, gcc is still dog slow optimizing compared to CCC. > And I do know from long TRU64 experience that optimizing for a > particular > EVx chip can make a big difference. > > The man page for the Dec C Compiler under 5.1A: > Compaq C V6.3-028 on Compaq Tru64 UNIX V5.1 (Rev. 732) > Compiler Driver V6.3-026 (sys) cc Driver > states: > (Note: There are two relevant options for ccc -arch and -tune.) > > -arch option > Specifies which version of the Alpha architecture to generate > instructions for. All Alpha processors implement a core set of > instruc- > tions and, in some cases, the following extensions: BWX > (byte/word- > manipulation extension), MVI (multimedia extension), FIX (square > root > and floating-point convert extension), and CIX (count > extension). (The > Alpha Architecture Reference Manual describes the extensions in > detail.) > > The option specified by the -arch option determines which > instructions > the compiler can generate: > > generic > Generate instructions that are appropriate for all Alpha > proces- > sors. This option is the default. > > host > Generate instructions for the processor that the compiler is > run- > ning on (for example, EV6 instructions on an EV6 processor). > > ev4,ev5 > Generate instructions for the EV4 processor (21064, 21064A, > 21066, > and 21068 chips) and EV5 processor (some 21164 chips). (Note > that > chip number 21164 is used for both EV5 and EV56 processors.) > > Applications compiled with this option will not incur any > emulation > overhead on any Alpha processor. > > ev56 > Generate instructions for EV56 processors (some 21164 chips). > > This option permits the compiler to generate any EV4 > instruction, > plus any instructions contained in the BWX extension. > > Applications compiled with this option may incur emulation > overhead > on EV4 and EV5 processors. > > ev6 Generate instructions for EV6 processors (21264 chips). > > This option permits the compiler to generate any EV6 > instruction, > plus any instructions contained in the following extensions: > BWX, > MVI, and FIX. > > Applications compiled with this option may incur emulation > overhead > on EV4, EV5, EV56, and PCA56 processors. > > ev67 > Generate instructions for EV67 processors (21264A chips). > > This option is the same as the ev6 option except that it > also per- > mits the compiler to generate any instructions contained in > the CIX > extension. > > If your application uses CIX instructions, it may incur > emulation > overhead on all processors that are older than EV67. > > pca56 > Generate instructions for PCA56 processors (21164PC chips). > > This option permits the compiler to generate any EV4 > instruction, > plus any instructions contained in the BWX and MVI > extensions. > > Applications compiled with this option may incur emulation > overhead > on EV4, EV5, and EV56 processors. > > A program compiled with any of the options will run on any Alpha > pro- > cessor. Beginning with DIGITAL UNIX V4.0 and continuing with > subse- > quent versions, the operating system kernel includes an > instruction > emulator. This capability allows any Alpha chip to execute and > produce > correct results from Alpha instructions--even if the some of the > instructions are not implemented on the chip. Applications using > emu- > lated instructions will run correctly, but may incur significant > emula- > tion overhead at run time. > > The psrinfo -v command can be used to determine which type of > processor > is installed on any given Alpha system. > > Note the following differences between the -arch evx and -tune > evx > options (where x designates a specific processor): > > + -arch evx implies -tune evx, but -tune evx does not imply > -arch > evx. > > + -arch evx can generate unguarded evx-specific instructions. > If > you run that application on a pre-evx processor, those > instruc- > tions may get emulated (and emulated instructions can be up > to > 1000 times slower than actual instructions). > > + -tune evx can generate evx-specific instructions, but those > are > always amask-guarded. That expands the code size but avoids > instruction emulation. > > + If you want the best performance possible on an evx > processor and > are not concerned about performance on earlier processors, > the > best choice would be -arch evx (which implies -tune evx). > > + If you want good performance on an evx processor but also > want the > application to run reasonably fast on earlier processors, > the best > choice would probably be -tune evx. > > =============== > -tune option > Instructs the optimizer to tune the application for a specific > version > of the Alpha hardware. This will not prevent the application > from run- > ning correctly on other versions of Alpha but it may run more > slowly > than generically-tuned code on those versions. > > The option argument can be one of the following, which selects > instruc- > tion tuning appropriate for the listed processor(s): > > generic > All Alpha processors. This is the default. > > host > The processor on which the code is compiled. > > ev4 The 21064, 21064A, and 21068 processors. > > ev5,ev56 > The 21164 processor. (Both EV5 and EV56 are numbered 21164.) > > ev6 The 21264 processor. > > ev67 > The 21264A processor. > > See also the -arch option for an explanation of the differences > between > -tune and -arch. > > > T.T.F.N. > William H. Magill > # Beige G3 [Rev A motherboard - 300 MHz 768 Meg] OS X 10.2.8 > # Flat-panel iMac (2.1) [800MHz - Super Drive - 768 Meg] OS X 10.3.7 > # PWS433a [Alpha 21164 Rev 7.2 (EV56)- 64 Meg] Tru64 5.1a > # XP1000 [Alpha 21264-3 (EV6) - 256 meg] FreeBSD 5.3 > # XP1000 [Alpha 21264-A (EV 6.7) - 384 meg] FreeBSD 5.3 > magill@mcgillsociety.org > magill@acm.org > magill@mac.com > whmagill@gmail.com > > _______________________________________________ > freebsd-alpha@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-alpha > To unsubscribe, send any mail to > "freebsd-alpha-unsubscribe@freebsd.org" > > !DSPAM:41e2a80f10651789918842! > > > -- Jeremy Tregunna jtregunna@blurgle.ca
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