Bug 189122

Summary:	[WHLSL] Enumerate which operations require uniform control flow and dynamically uniform expressions
Product:	WebKit	Reporter:	Myles C. Maxfield <mmaxfield>
Component:	WebGPU	Assignee:	Nobody <webkit-unassigned>
Status:	RESOLVED FIXED
Severity:	Normal	CC:	jonlee, webkit-bug-importer
Priority:	P2	Keywords:	InRadar
Version:	WebKit Nightly Build
Hardware:	Unspecified
OS:	Unspecified
See Also:	https://bugs.webkit.org/show_bug.cgi?id=189125 https://bugs.webkit.org/show_bug.cgi?id=189123
Bug Depends on:
Bug Blocks:	176199, 189202

Description Myles C. Maxfield 2018-08-29 16:35:44 PDT

Indexing into an array of textures requires a dynamically uniform expression
sample() involves an implicit derivative, and so requires uniform control flow

Comment 1 Radar WebKit Bug Importer 2018-09-12 18:50:46 PDT

<rdar://problem/44402999>

Comment 2 Myles C. Maxfield 2018-09-22 23:51:38 PDT

The following functions require uniform control flow:

ddx()
ddy()
AllMemoryBarrierWithGroupSync()
DeviceMemoryBarrierWithGroupSync()
GroupMemoryBarrierWithGroupSync()
Sample()
SampleBias()
Gather()
GatherRed()
GatherGreen()
GatherBlue()
GatherAlpha()
SampleCmp()
GatherCmp()
GatherCmpRed()
GatherCmp()
GatherCmpRed()

Comment 3 Myles C. Maxfield 2018-09-22 23:52:57 PDT

Indexing into an array which contains textures requires dynamically uniform expressions. I think that's the only operation.

Comment 4 Myles C. Maxfield 2018-09-22 23:54:08 PDT

I suppose this is done now.

Comment 5 Myles C. Maxfield 2018-10-13 14:50:33 PDT

Migrated to https://github.com/gpuweb/WHLSL/issues/58