Possible FPU emulation bug in 2.5.1?

Zoltar · 01 January 2013, 19:08

Greetings to you all. This is my first post on here after lurking for a wee while.

I was trying out some benchmarking using Real3D 1.4.2 in WinUAE and noticed some errors in the final image when rendering using the TurboReal executable.

Interestingly, it only seems to affect, in this scene at least, the bump-mapped texture on the teapot. I'll try some older versions of WinUAE and get back with some more results.

In the meantime, Happy New Year!

SJ

Zoltar · 01 January 2013, 20:28

After working through the previous WinUAE versions i've found that 2.0.1 is the last one that produces the correct image.

2.1.0 thru 2.3.0 all produce the same garbled image as above. In 2.3.1 thru 2.3.3 both the Real and TurboReal versions of the program crash the emulated Amiga. 2.4.0 thru to the current version all have the same problem.

I've been testing using JIT 68030 CPU + 68882 on the 'Fastest possible' setting.

Hope that helps you out a wee bit.

SJ

Toni Wilen · 01 January 2013, 20:40

Important question that needs answer: does it happen without JIT?

Zoltar · 01 January 2013, 20:53

Quote:

Originally Posted by Toni Wilen

Important question that needs answer: does it happen without JIT?

In 2.5.1, yes it does. Would it be worth going through all the older versions testing that?

SJ

Toni Wilen · 02 January 2013, 10:05

Unfortunately there is no FPU emulation differences between 2.0.1 and 2.1.0. Could you test which beta introduced the problem?

All 2.1.0 betas are still available http://www.winuae.net/files/b/winuae_2100bx.zip (where x = 13 to 25, earlier 2.1 betas are named winuae_2020bx.zip, 1 to 12)

It looks like accuracy difference, perhaps FPU is in different mode in later versions.

Zoltar · 02 January 2013, 15:28

Quote:

Originally Posted by Toni Wilen

Unfortunately there is no FPU emulation differences between 2.0.1 and 2.1.0. Could you test which beta introduced the problem?

All 2.1.0 betas are still available http://www.winuae.net/files/b/winuae_2100bx.zip (where x = 13 to 25, earlier 2.1 betas are named winuae_2020bx.zip, 1 to 12)

It looks like accuracy difference, perhaps FPU is in different mode in later versions.

Ok dude, i'll have a crack at it later today. Could you check out the download link? It's giving me a 404 error here.

SJ

Toni Wilen · 02 January 2013, 15:31

You missed "x = <some number>". Read above post again

Zoltar · 02 January 2013, 16:38

Quote:

Originally Posted by Toni Wilen

You missed "x = <some number>". Read above post again

Ha! Now that i'm fully awake that makes perfect sense.

SJ

Zoltar · 02 January 2013, 20:35

OK dude, here goes...

I tried out 2.1.0 first, before I tried any of the betas, making a new test configuration file with it first just so I could save a few seconds fiddling about in between each test and, interestingly, it rendered the image correctly. Indeed, all the 2.1.0 betas worked fine when using that .uae file.

I then tried the .uae I used yesterday, which is my main A1200HD config that I use 90% of the time and the issue first appears in b14, continuing on through all the remaining betas.

I wondered if it was just as simple as needing a new configuration file so I tried making a new .uae with 2.5.1 to see if it made any difference but it still produces the same messed up results. Using the config that worked with the betas above also made no difference.

Hopefully that sheds some light on things for you.

SJ

Toni Wilen · 02 January 2013, 20:43

Thanks.

Could you find the difference in config file? CPU panel looks same? What about Direct3D vs DirectDraw or filter settings? At least D3D may change FPU mode but it should have been fixed long time ago.

Or just attach both working and non-working config file.

Zoltar · 02 January 2013, 22:31

Quote:

Originally Posted by Toni Wilen

Thanks.

Could you find the difference in config file? CPU panel looks same? What about Direct3D vs DirectDraw or filter settings? At least D3D may change FPU mode but it should have been fixed long time ago.

Or just attach both working and non-working config file.

I think that's it dude. Using the working 2.1.0 config file in 2.5.1 with DirectDraw selected produces the correct result. Changing to Direct3D mode reproduces the error.

If I save the working 2.1.0 config back out of 2.5.1, then restart the emulator, changing between DirectDraw or Direct3D now makes no difference and it generates the same scrambled up texture on the teapot.

Is anything else you can think of that you'd like me to try?

SJ

Toni Wilen · 04 January 2013, 17:50

Does http://www.winuae.net/files/b/winuae.zip fix it?

Zoltar · 04 January 2013, 23:07

Quote:

Originally Posted by Toni Wilen

Does http://www.winuae.net/files/b/winuae.zip fix it?

Yes, that works fine now dude. In Direct3D or DirectDraw, with any of my configs, it now renders correctly. Excellent!

SJ

Toni Wilen · 05 January 2013, 14:52

Great.

It was stupid bug, routine that gets and sets host FPU precision/rounding modes, I assumed it returns old mode value but it returns value you just set.

Usually functions that do both get and set returns old state, not new state.

01 January 2013, 19:08	#1
Zoltar Registered User Join Date: May 2012 Location: Scotland Posts: 34	Possible FPU emulation bug in 2.5.1? Greetings to you all. This is my first post on here after lurking for a wee while. I was trying out some benchmarking using Real3D 1.4.2 in WinUAE and noticed some errors in the final image when rendering using the TurboReal executable. Interestingly, it only seems to affect, in this scene at least, the bump-mapped texture on the teapot. I'll try some older versions of WinUAE and get back with some more results. In the meantime, Happy New Year! SJ Attached Thumbnails

01 January 2013, 20:28	#2
Zoltar Registered User Join Date: May 2012 Location: Scotland Posts: 34	After working through the previous WinUAE versions i've found that 2.0.1 is the last one that produces the correct image. 2.1.0 thru 2.3.0 all produce the same garbled image as above. In 2.3.1 thru 2.3.3 both the Real and TurboReal versions of the program crash the emulated Amiga. 2.4.0 thru to the current version all have the same problem. I've been testing using JIT 68030 CPU + 68882 on the 'Fastest possible' setting. Hope that helps you out a wee bit. SJ Attached Thumbnails

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01 January 2013, 20:40	#3
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,505	Important question that needs answer: does it happen without JIT?

02 January 2013, 10:05	#5
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,505	Unfortunately there is no FPU emulation differences between 2.0.1 and 2.1.0. Could you test which beta introduced the problem? All 2.1.0 betas are still available http://www.winuae.net/files/b/winuae_2100bx.zip (where x = 13 to 25, earlier 2.1 betas are named winuae_2020bx.zip, 1 to 12) It looks like accuracy difference, perhaps FPU is in different mode in later versions.

02 January 2013, 15:31	#7
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,505	You missed "x = <some number>". Read above post again

02 January 2013, 20:35	#9
Zoltar Registered User Join Date: May 2012 Location: Scotland Posts: 34	OK dude, here goes... I tried out 2.1.0 first, before I tried any of the betas, making a new test configuration file with it first just so I could save a few seconds fiddling about in between each test and, interestingly, it rendered the image correctly. Indeed, all the 2.1.0 betas worked fine when using that .uae file. I then tried the .uae I used yesterday, which is my main A1200HD config that I use 90% of the time and the issue first appears in b14, continuing on through all the remaining betas. I wondered if it was just as simple as needing a new configuration file so I tried making a new .uae with 2.5.1 to see if it made any difference but it still produces the same messed up results. Using the config that worked with the betas above also made no difference. Hopefully that sheds some light on things for you. SJ

02 January 2013, 20:43	#10
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,505	Thanks. Could you find the difference in config file? CPU panel looks same? What about Direct3D vs DirectDraw or filter settings? At least D3D may change FPU mode but it should have been fixed long time ago. Or just attach both working and non-working config file.

04 January 2013, 17:50	#12
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,505	Does http://www.winuae.net/files/b/winuae.zip fix it?

05 January 2013, 14:52	#14
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,505	Great. It was stupid bug, routine that gets and sets host FPU precision/rounding modes, I assumed it returns old mode value but it returns value you just set. Usually functions that do both get and set returns old state, not new state.

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