1736076 - WebGL extension KHR_parallel_shader_compile doesn't appear to be supported

Status: NEW

(Core :: Graphics: CanvasWebGL, enhancement)

Description

[Rémi Verschelde]

According to MDN, the KHR_parallel_shader_compile WebGL 1.0 extension should be supported in Firefox 80+ on desktop.

Yet websites such as WebGL Caps Viewer don't list it, and my application Godot Engine is unable to use it to compile shaders in parallel. It is however reported as supported and working fine with latest Chrome and Chromium.

I tested both on Windows and Linux, with both Intel and AMD drivers (Linux system details listed below), and neither combination seems to expose KHR_parallel_shader_compile in Firefox. I've had multiple users confirm the same issue on both Windows and Linux (though I don't know with which GPU drivers, if that's relevant to the availability of the extension).

I tried enabling webgl.enable-draft-extensions and webgl.enable-privileged-extensions but that doesn't change the result.

The feature implementation was tracked in https://bugzilla.mozilla.org/show_bug.cgi?id=1536674, but it seems the resolution was a patch that added the extension to the enum, but no actual code to implement it? https://phabricator.services.mozilla.com/D32056

So is MDN incorrect and the extension is actually not supported in Firefox currently?

I tested on current Nightly (95) and release (93). I tried FF 80 but it seems broken on my Linux system, but I had one teammate test and confirm that the extension is also not present there.

$ inxi -CSG
System:    Host: cauldron Kernel: 5.14.12-desktop-2.mga9 x86_64 bits: 64 Desktop: KDE Plasma 5.22.3 Distro: Mageia 9 mga9 
CPU:       Info: Quad Core model: Intel Core i7-8705G bits: 64 type: MT MCP cache: L2: 8 MiB 
           Speed: 3066 MHz min/max: 800/3100 MHz Core speeds (MHz): 1: 3066 2: 3100 3: 3100 4: 3091 5: 3098 6: 2955 7: 3029 
           8: 3025 
Graphics:  Device-1: Intel HD Graphics 630 driver: i915 v: kernel 
           Device-2: Advanced Micro Devices [AMD/ATI] Polaris 22 XL [Radeon RX Vega M GL] driver: amdgpu v: kernel 
           Device-3: Cheng Uei Precision Industry (Foxlink) HP Wide Vision FHD Camera type: USB driver: uvcvideo 
           Display: x11 server: Mageia X.org 1.21.0.99 driver: loaded: intel,v4l resolution: 1920x1080~100Hz 
           OpenGL: renderer: Mesa Intel HD Graphics 630 (KBL GT2) v: 4.6 Mesa 21.2.4

Comment 1

[Rémi Verschelde]

(In reply to Rémi Verschelde from comment #0)

The feature implementation was tracked in https://bugzilla.mozilla.org/show_bug.cgi?id=1536674, but it seems the resolution was a patch that added the extension to the enum, but no actual code to implement it? https://phabricator.services.mozilla.com/D32056

Sorry about that, I had reviewed the bug a bit too quickly, there are links to various intermediate patches which implement the feature.

Comment 2

[Rémi Verschelde]

So on second review, it seems to me that https://bugzilla.mozilla.org/show_bug.cgi?id=1536674 was wrongly closed as fixed by https://hg.mozilla.org/mozilla-central/rev/c534308b0e49 in https://bugzilla.mozilla.org/show_bug.cgi?id=1536674#c5

The actual implementation of the draft extension seems to be https://phabricator.services.mozilla.com/D83315#change-9IYWqbnfEgqP linked in https://bugzilla.mozilla.org/show_bug.cgi?id=1536674#c6, which has yet to be merged in trunk.

So MDN should be updated to remove the reference that FF supports the extension since version 80, likewise with https://caniuse.com/mdn-api_khr_parallel_shader_compile and other similar references.

And https://bugzilla.mozilla.org/show_bug.cgi?id=1536674 should probably be reopened.

Comment 3

[Virginia (please send need info request to Brindusa Tot)]

Hi Rémi,

Thanks for your report and for providing information about it.
I'll be setting up a component so the Core WebGL team can take a look and advice.

Regards,
Virginia

Comment 4

[Ruth John]

I'm happy to update MDN with the relevant information. Do we have an indication of when this will be merged in trunk? The version associated with this bug is 95 - should I go with that? Thanks

Comment 5

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:jgilbert, could you have a look please?

For more information, please visit auto_nag documentation.

Comment 6

[Kelsey Gilbert [:jgilbert]]

Seems like I can't reopen bug 1536674, so I'll rename it I guess?

Comment 7

[Hamish Willee]

Can you please confirm the only change from this is that the Firefox compatibility with version 80 needs to be set as false? This is done in https://github.com/mdn/browser-compat-data/pull/13291

Comment 8

[Kelsey Gilbert [:jgilbert]]

Correct.

Comment 9

[BugBot [:suhaib / :marco/ :calixte]]

The bug has a release status flag that shows some version of Firefox is affected, thus it will be considered confirmed.