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Thorsten Froehlich <tho### [at] trf de> wrote:
> Warp wrote:
> > Thorsten Froehlich <tho### [at] trfde> wrote:
> >> Yes, but what use are instructions you won't be able to use in the future
> >> and your are already recommended not to use now?
> >
> > As long as the hardware supports x87, I see absolutely no rational reason
> > why an OS would drop support for 99% of programs just because it doesn't
> > want the FPU to be used.
> Tell that Microsoft, Apple and the Linux community.
Windows, MacOS X and Linux all fully support programs which use the FPU.
If they wouldn't, at least 99% of programs would stop working.
I still see no rational reason to deliberately and on purpose break
99% of programs. What would be the point? Task switching takes a negligible
amount of time, so skipping storing and loading the FPU registers would be
a rather useless micro-optimization.
What other benefit could there be, from the point of view of an OS?
(Sure, they might say "please use SSE rather than the FPU from now on",
but that's a completely different thing from actually going and actively
making most programs out there stop working, for no good reason. The
hardware is there, so why not use it? It doesn't make any sense.)
--
- Warp
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Thorsten Froehlich <tho### [at] trfde> wrote:
> You asked what a fast SSE trigonometry implementation would look like, not
> what code your compiler generates when targeting a P4. So clearly you should
> not be looking at the x87 implementation using the fsincos opcode when you
> want to know how the SSE code would look like!?!
It's obviously telling me that whatever the SSE implementation might be,
it's *not* faster (nor even equally fast) than the fsincos opcode in my
computer, which contradicts what you said that it could be done in software
more efficiently. If it could be done more efficiently, wouldn't gcc do just
that when I instruct it to use SSE?
Is SSE different in x86_64 than it is in x86_32?
--
- Warp
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Warp wrote:
> Thorsten Froehlich <tho### [at] trfde> wrote:
>> Warp wrote:
>>> Thorsten Froehlich <tho### [at] trfde> wrote:
>>>> Yes, but what use are instructions you won't be able to use in the future
>>>> and your are already recommended not to use now?
>>> As long as the hardware supports x87, I see absolutely no rational reason
>>> why an OS would drop support for 99% of programs just because it doesn't
>>> want the FPU to be used.
>
>> Tell that Microsoft, Apple and the Linux community.
>
> Windows, MacOS X and Linux all fully support programs which use the FPU.
> If they wouldn't, at least 99% of programs would stop working.
>
> I still see no rational reason to deliberately and on purpose break
> 99% of programs.
DO NOT ASK ME! They are going to do it, period! Is it really that difficult
to understand? What the heck do you argue with me about the rationale behind
*their* decisions?
Thorsten
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Warp wrote:
> Thorsten Froehlich <tho### [at] trfde> wrote:
>> You asked what a fast SSE trigonometry implementation would look like, not
>> what code your compiler generates when targeting a P4. So clearly you should
>> not be looking at the x87 implementation using the fsincos opcode when you
>> want to know how the SSE code would look like!?!
>
> It's obviously telling me that whatever the SSE implementation might be,
> it's *not* faster (nor even equally fast) than the fsincos opcode in my
> computer, which contradicts what you said that it could be done in software
> more efficiently. If it could be done more efficiently, wouldn't gcc do just
> that when I instruct it to use SSE?
Why do you argue with me about what Microsoft, Apple, Intel and AMD say? I
have no intention to discuss this any further, sorry. This is ridiculous! If
you don't know how to get the performance out of your compiled program that
Microsoft, Apple, Intel and AMD say is possible, then that is not my
problem. If you seriously believe Microsoft, Apple, Intel and AMD would make
suggestions how software runs slower on the latest x86 processors, then
believe it, I cannot change what you want to believe.
Thorsten
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Thorsten Froehlich <tho### [at] trfde> wrote:
> DO NOT ASK ME! They are going to do it, period! Is it really that difficult
> to understand? What the heck do you argue with me about the rationale behind
> *their* decisions?
What decisions? Do you have any concrete reference eg. to some online
linux community resource where they are saying that support for programs
using the FPU will be dropped? Because I would certainly like to know how
it makes any sense.
--
- Warp
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Thorsten Froehlich <tho### [at] trfde> wrote:
> Why do you argue with me about what Microsoft, Apple, Intel and AMD say? I
> have no intention to discuss this any further, sorry. This is ridiculous! If
> you don't know how to get the performance out of your compiled program that
> Microsoft, Apple, Intel and AMD say is possible, then that is not my
> problem. If you seriously believe Microsoft, Apple, Intel and AMD would make
> suggestions how software runs slower on the latest x86 processors, then
> believe it, I cannot change what you want to believe.
Then I only must conclude that Microsoft, Apple, Intel and AMD are lying
because I can't see any actual proof of that in my computer.
--
- Warp
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Gentleman, leave this discussion to 2008...
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Warp wrote:
> Thorsten Froehlich <tho### [at] trfde> wrote:
>> DO NOT ASK ME! They are going to do it, period! Is it really that difficult
>> to understand? What the heck do you argue with me about the rationale behind
>> *their* decisions?
>
> What decisions? Do you have any concrete reference eg. to some online
> linux community resource where they are saying that support for programs
> using the FPU will be dropped? Because I would certainly like to know how
> it makes any sense.
I believe I have provided more than enough references. You can Google for
more information just as easily as I can.
Thorsten
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Thorsten Froehlich <tho### [at] trfde> wrote:
> I believe I have provided more than enough references. You can Google for
> more information just as easily as I can.
So basically you are saying that, among others, linux is going to drop
support for programs using FPU opcodes, and you don't have any concrete
proof of that to show me.
--
- Warp
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On Thu, 01 Jan 2009 02:46:55 +0100, Warp <war### [at] tagpovrayorg> wrote:
> At least in the past Intel processors had the strange rule that you
> cannot
> use the FPU and the SSE unit at the same time. I don't know if they have
> fixed that limitation later.
I think that was FPU and MMX, the reason being that they used the same
registers.
--
FE
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