Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.forth > #4640
| From | anton@mips.complang.tuwien.ac.at (Anton Ertl) |
|---|---|
| Subject | Re: Forth Performance Question |
| Newsgroups | comp.lang.forth |
| References | <f0fc528e-2fdb-42af-a66d-976ebfa73b88@c8g2000prn.googlegroups.com> <14589696958436@frunobulax.edu> |
| Organization | Institut fuer Computersprachen, Technische Universitaet Wien |
| Date | 2011-08-07 16:18 +0000 |
| Message-ID | <2011Aug7.181837@mips.complang.tuwien.ac.at> (permalink) |
mhx@iae.nl (Marcel Hendrix) writes:
>TS <thinksquared@gmail.com> wrote Re: Forth Performance Question
>> public class Test {
>> public static void main(String[] args) {
>> for(int i = 0; i < 100000000; ++i){
>> foo();
>> }
>> }
>> private static final int foo(){
>> return 1*1000000;
>> }
>> }
>
>The compiler will not produce code for 1*1000000 (it's a constant),
>and therefore the foo() function is inlined in main. Inlining
>probably doesn't even happen because the efect of foo() can not
>be observed outside the for loop. In that case the JIT may not even
>compile the loop, and your only measuring the startup time of the
>code. To do a true comparison you need multiply not 1 and 1000000,
>but a and b, where a and b are integer arguments to main (so the JIT
>can not predict what they are).
Even that would probably be optimized away completely, because foo()
has no side effects and its result is thrown away. Even if you
eliminate that, multiplying an loop-invariant a and b produces a
loop-invariant result, so the optimizer will likely produce code that
performs only one multiplication.
Better write a program that does something slightly useful; it's less
likely that the compiler can optimize that into oblivion.
- anton
--
M. Anton Ertl http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
New standard: http://www.forth200x.org/forth200x.html
EuroForth 2011: http://www.euroforth.org/ef11/
Back to comp.lang.forth | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Forth Performance Question TS <thinksquared@gmail.com> - 2011-08-06 20:43 -0700
Re: Forth Performance Question "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2011-08-07 01:02 -0400
Re: Forth Performance Question Chris Hinsley <chris.hinsley@gmail.com> - 2011-08-16 12:09 +0100
Re: Forth Performance Question stephenXXX@mpeforth.com (Stephen Pelc) - 2011-08-16 14:08 +0000
Re: Forth Performance Question mhx@iae.nl (Marcel Hendrix) - 2011-08-07 07:45 +0200
Re: Forth Performance Question anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2011-08-07 16:18 +0000
Re: Forth Performance Question Bruno Gauthier <bgauthier@free.fr> - 2011-08-07 07:53 +0200
Re: Forth Performance Question Julian Fondren <ayrnieu@gmail.com> - 2011-08-07 01:01 -0500
Re: Forth Performance Question Albert van der Horst <albert@spenarnc.xs4all.nl> - 2011-08-07 12:50 +0000
Re: Forth Performance Question stephenXXX@mpeforth.com (Stephen Pelc) - 2011-08-07 11:46 +0000
Re: Forth Performance Question Arnold Doray <thinksquared@gmail.com> - 2011-08-10 17:03 +0000
Re: Forth Performance Question Julian Fondren <ayrnieu@gmail.com> - 2011-08-10 13:35 -0500
Re: Forth Performance Question Arnold Doray <thinksquared@gmail.com> - 2011-08-11 15:05 +0000
Re: Forth Performance Question anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2011-08-11 16:26 +0000
Re: Forth Performance Question Arnold Doray <thinksquared@gmail.com> - 2011-08-12 08:15 +0000
Re: Forth Performance Question "Elizabeth D. Rather" <erather@forth.com> - 2011-08-11 22:29 -1000
Re: Forth Performance Question Arnold Doray <thinksquared@gmail.com> - 2011-08-12 10:09 +0000
Re: Forth Performance Question Julian Fondren <ayrnieu@gmail.com> - 2011-08-12 08:15 -0500
Re: Forth Performance Question anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2011-08-12 09:31 +0000
Re: Forth Performance Question crc <charles.childers@gmail.com> - 2011-08-11 10:27 -0700
Re: Forth Performance Question Julian Fondren <ayrnieu@gmail.com> - 2011-08-11 13:18 -0500
Re: Forth Performance Question "Elizabeth D. Rather" <erather@forth.com> - 2011-08-11 12:00 -1000
Re: Forth Performance Question Howerd <howerdo@yahoo.co.uk> - 2011-08-11 15:13 -0700
Re: Forth Performance Question Charles Childers <crc_nospam@retroforth.org> - 2011-08-11 20:52 -0400
Re: Forth Performance Question "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2011-08-12 02:19 -0400
Re: Forth Performance Question Julian Fondren <ayrnieu@gmail.com> - 2011-08-12 02:10 -0500
Re: Forth Performance Question "Elizabeth D. Rather" <erather@forth.com> - 2011-08-11 21:48 -1000
Re: Forth Performance Question "Elizabeth D. Rather" <erather@forth.com> - 2011-08-11 21:41 -1000
Re: Forth Performance Question Charles Childers <crc_nospam@retroforth.org> - 2011-08-10 23:33 -0400
Re: Forth Performance Question Ron Aaron <rambamist@gmail.com> - 2011-08-11 08:59 +0300
Re: Forth Performance Question Arnold Doray <thinksquared@gmail.com> - 2011-08-11 13:48 +0000
Re: Forth Performance Question Charles Childers <crc@retroforth.org> - 2011-08-11 10:30 -0400
Re: Forth Performance Question Ron Aaron <rambamist@gmail.com> - 2011-08-11 08:46 +0300
Re: Forth Performance Question arc <arc@vorsicht-bissig.de> - 2011-08-12 12:20 +0000
Re: Forth Performance Question Arnold Doray <thinksquared@gmail.com> - 2011-08-12 13:59 +0000
Re: Forth Performance Question stephenXXX@mpeforth.com (Stephen Pelc) - 2011-08-12 15:11 +0000
Re: Forth Performance Question Arnold Doray <thinksquared@gmail.com> - 2011-08-12 17:49 +0000
Re: Forth Performance Question stephenXXX@mpeforth.com (Stephen Pelc) - 2011-08-12 19:38 +0000
Re: Forth Performance Question "Elizabeth D. Rather" <erather@forth.com> - 2011-08-12 12:41 -1000
Re: Forth Performance Question Arnold Doray <thinksquared@gmail.com> - 2011-08-13 03:35 +0000
Re: Forth Performance Question "Elizabeth D. Rather" <erather@forth.com> - 2011-08-12 17:52 -1000
Re: Forth Performance Question Paul Rubin <no.email@nospam.invalid> - 2011-08-12 23:55 -0700
Re: Forth Performance Question Albert van der Horst <albert@spenarnc.xs4all.nl> - 2011-08-14 09:01 +0000
Re: Forth Performance Question Paul Rubin <no.email@nospam.invalid> - 2011-08-14 01:36 -0700
Re: Forth Performance Question Arnold Doray <thinksquared@gmail.com> - 2011-08-15 01:43 +0000
Re: Forth Performance Question Hugh Aguilar <hughaguilar96@yahoo.com> - 2011-08-15 16:59 -0700
Re: Forth Performance Question Mark Wills <markrobertwills@yahoo.co.uk> - 2011-08-16 03:25 -0700
Re: Forth Performance Question Arnold Doray <thinksquared@gmail.com> - 2011-08-16 11:22 +0000
Re: Forth Performance Question Hugh Aguilar <hughaguilar96@yahoo.com> - 2011-08-16 14:37 -0700
Re: Forth Performance Question Arnold Doray <thinksquared@gmail.com> - 2011-08-19 14:11 +0000
Re: Forth Performance Question Hugh Aguilar <hughaguilar96@yahoo.com> - 2011-08-22 19:52 -0700
Re: Forth Performance Question Zbiggy <zbigniew2011REMOVE@gmail.REMOVE.com> - 2011-08-13 02:28 +0200
Re: Forth Performance Question Zbiggy <zbigniew2011REMOVE@gmail.REMOVE.com> - 2011-08-12 20:53 +0200
csiph-web