Did I reach some SPIR-V execution limit on Intel UHD 620?

[stezkmil]

Hello,

I didn't find a forum dedicated to rendering APIs like Vulkan, so I try here. I ran into problems with our GLSL shaders being executed on an Intel GPU. I attach a RenderDoc capture to show the issue. There is a textured, evironment lit and directional light lit sphere. On it are some wireframe like artifacts. Looks like the shading is wrong on triangle edges. This problem appears only on the expensive paths of the shader where there are many instructions to execute. Not on runs where there is no shadow mapping or no other texturing. The problem disappears when I lower the amount of texture fetches. Also lowering the size of a constant array containing precomputed blue noise seemed to help. I don't think we do anything extraordinary in our shaders. Just the usual stuff - environment lighting, direct lighting, shadow mapping, normal mapping and so on. It is worth noting that we mainly run this on nVidias without any problems and we can't just simplify the code to run on Intels. We need to preserve the quality of the shading.

I don't know how to tackle this one. Where do I look if we broke some SPIR-V size limit? Validation layers didn't tell me anything.

To show that this is not a bug in our code, you can open the capture and inspect the pixel, for example 195,81 . This pixel is ok and has a color value of 0.37,0.37,0.14. Below it is a pixel 195,82. This one has wrong values (darker than it should be) of 0.27,0.28,0.13. Now when I hit the Debug button on this wrong pixel, the values shown in the final outColor register show me values 0.368, 0.374, 0.146. So values very close to the "right" values. Where did the difference come from, I have no idea.

My driver version is 31.0.101.2111 but it was the same also on a much older driver.

Thanks for any advice,

Milan

[Alberto_R_Intel]

stezkmil, Thank you for posting in the Intel® Communities Support.

For this specific scenario, I will do further research on this matter to try to provide the information you are looking for or to point you in the right direction for the proper technical support. As soon as I get any updates, I will post all the details on this thread.

Any questions, please let me know.

Regards,

Albert R.

Intel Customer Support Technician

[stezkmil]

Much apperciated.

Regards,

Milan

[Alberto_R_Intel]

Hello stezkmil, I just received an update on this matter.

While we are still working on this topic, we just wanted to confirm:

Would it be possible for you to test this scenario on newer hardware like the Intel® 11th or 12th generation and see if the same happens?

Could you please provide a detailed description step-by-step on how to run it, a video sample, or an app sample about what you are doing? Videos, screenshots showing up the issue for us to try to replicate it on newer hardware?

Where do you work? Are you currently performing a company project?

We recommend to install the latest graphics drivers, the latest Windows* updates, and the latest BIOS updates.

Please attach the SSU report so we can verify further details about the components in your platform, check all the options in the report including the one that says "3rd party software logs":

https://downloadcenter.intel.com/download/25293/Intel-System-Support-Utility-for-Windows-?product=91600

Regards,

Albert R.

Intel Customer Support Technician

[stezkmil]

Hi,

unfortunately I don't have any newer Intel hardware available.

I have an app sample which I could provide, but I can not make it public on this forum. I would provide a link in an email or some private message if that is possible on these forums (didn't find how to do it).

It is a company project (automotive industry).

I had the latest graphics driver installed (31.0.101.2111)

Regards,

Milan

[Alberto_R_Intel]

stezkmil, Thank you very much for sharing the SSU report.

Sure, no problem, I will send you an email so you can reply back to it with the app sample. Please verify your inbox.

Regards,

Albert R.

Intel Customer Support Technician

[Alberto_R_Intel]

Hello stezkmil, I just received an update on this matter.

I sent you an email with private information. Please verify your inbox.

Regards,

Albert R.

Intel Customer Support Technician

[Jean_Intel]

Hello stezkmil,

I hope you are doing fine.

This post is to let you know that our research is still in process. We don't have an answer right now, however, we will post the response on this thread once available.

Best regards, 

Jean O.  

Intel Customer Support Technician

[Alberto_R_Intel]

Hello stezkmil, Thank you very much for your patience.

This is just to inform you know that we are still working on this scenario. As soon as I get any updates, I will post all the details on this thread.

Regards,

Albert R.

Intel Customer Support Technician

[stezkmil]

Hello,

thanks for the update. Looking forward to the results of the investigation.

Regards,

Milan

[Alberto_R_Intel]

Hello stezkmil, You are very welcome.

We will provide the results of the lab as soon as possible.

Regards,

Albert R.

Intel Customer Support Technician

[Alberto_R_Intel]

Hello stezkmil, I just received an update on this matter.

After reviewing the case, we determined that the best course of action, in this case, in order for you to gather the information you are looking for, will be for you to visit, sign in and submit your inquiry to our Intel® Developer Software Forums for further assistance on this topic:

https://community.intel.com/t5/Developer-Software-Forums/ct-p/developer-software-forums

Regards,

Albert R.

Intel Customer Support Technician