Groups > comp.lang.java.programmer > #6897

Re: higher precision doubles

From	supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com>
Newsgroups	comp.lang.java.programmer
Subject	Re: higher precision doubles
Date	2011-08-09 00:42 -0400
Organization	supercalifragilisticexpialadiamaticonormalizeringelimatisticantations
Message-ID	<j1qdrt$30a$1@speranza.aioe.org> (permalink)
References	<j1hqc1$1ch$1@news.albasani.net> <cOqdnfXfM99lhaDTnZ2dnUVZ_vednZ2d@earthlink.com>

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On 06/08/2011 6:35 AM, Patricia Shanahan wrote:
> In general, a Java implementation must make its floating point
> arithmetic give the same results as the 32 and 64 bit basic formats. If
> "strictfp" is off, the implementation can carry extra extra exponent
> bits, avoiding some cases of overflow and underflow, but is not required
> to do so. Even without strictfp, the mantissa sizes and therefore the
> precision are fixed.

How does that interact with JIT, though? On x86, the simplest way for 
JIT to make non-strictfp code use the FPU would be to just load the 
initial values into the (80-bit-wide!) registers and perform FADDs, 
FMULs, etc. on them. As long as the computation stayed in registers the 
higher precision then ought to remain in effect -- for JITted code. 
Adding extra code to mask off 16 of the register bits (or the mantissa 
subset of the extra bits) after every FP op would slow things down. Is 
the JLS interpreted to require the JIT do this (for non-strictfp code)? 
And, if not, what does the HotSpot JIT do in actuality?

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higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-06 00:20 +0200
  Re: higher precision doubles Patricia Shanahan <pats@acm.org> - 2011-08-06 03:35 -0700
    Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-06 13:03 +0200
      Re: higher precision doubles BGB <cr88192@hotmail.com> - 2011-08-06 12:20 -0700
        Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-06 23:30 +0200
          Re: higher precision doubles BGB <cr88192@hotmail.com> - 2011-08-06 16:12 -0700
            Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-07 01:35 +0200
              Re: higher precision doubles BGB <cr88192@hotmail.com> - 2011-08-06 19:26 -0700
    Re: higher precision doubles supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-08-09 00:42 -0400
      Re: higher precision doubles Patricia Shanahan <pats@acm.org> - 2011-08-09 04:07 -0700
        Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-09 14:00 +0200
          Re: higher precision doubles Patricia Shanahan <pats@acm.org> - 2011-08-09 09:07 -0700
            Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-10 08:50 +0200
        Re: higher precision doubles supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-08-10 20:16 -0400
      Re: higher precision doubles Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-08-09 10:11 -0500
        Re: higher precision doubles Arne Vajhøj <arne@vajhoej.dk> - 2011-08-09 22:40 -0400
          Re: higher precision doubles Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-08-09 22:06 -0500
            Re: higher precision doubles BGB <cr88192@hotmail.com> - 2011-08-10 08:53 -0700
  Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-06 21:24 +0200
    Re: higher precision doubles markspace <-@.> - 2011-08-06 13:29 -0700
      Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-06 23:20 +0200
        Re: higher precision doubles markspace <-@.> - 2011-08-06 15:43 -0700
          Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-07 01:06 +0200
            Re: higher precision doubles Patricia Shanahan <pats@acm.org> - 2011-08-06 16:21 -0700
              Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-07 01:34 +0200
                Re: higher precision doubles Patricia Shanahan <pats@acm.org> - 2011-08-06 21:32 -0700
                Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-07 17:24 +0200
                Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-07 17:39 +0200
                Re: higher precision doubles Patricia Shanahan <pats@acm.org> - 2011-08-07 09:26 -0700
                Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-07 21:23 +0200
                Re: higher precision doubles Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-07 20:48 -0400
                Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-08 09:05 +0200
                Re: higher precision doubles Patricia Shanahan <pats@acm.org> - 2011-08-08 05:37 -0700
                Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-08 19:08 +0200
                Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-08 19:16 +0200
                Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-08 19:29 +0200
                Re: higher precision doubles Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-08-08 21:34 -0500
                Re: higher precision doubles BGB <cr88192@hotmail.com> - 2011-08-08 13:49 -0700
                Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-09 01:08 +0200
                Re: higher precision doubles BGB <cr88192@hotmail.com> - 2011-08-09 02:44 -0700
                Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-09 12:52 +0200
                Re: higher precision doubles BGB <cr88192@hotmail.com> - 2011-08-09 13:15 -0700
                Re: higher precision doubles BGB <cr88192@hotmail.com> - 2011-08-07 13:51 -0700
              Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-07 01:59 +0200
        Re: higher precision doubles Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-08-08 21:03 -0500
    Re: higher precision doubles Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-06 17:33 -0400
    Re: higher precision doubles Patricia Shanahan <pats@acm.org> - 2011-08-06 14:51 -0700
      Re: higher precision doubles Jan Burse <janburse@fastmail.fm> - 2011-08-07 00:57 +0200

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