Bug 189125

Summary:

[WHLSL] Implement dynamically uniform expression restrictions

Product:

WebKit

Reporter:

Myles C. Maxfield <mmaxfield>

Component:

WebGPU

Assignee:

Myles C. Maxfield <mmaxfield>

Status:

RESOLVED MOVED

Severity:

Normal

CC:

jonlee, webkit-bug-importer

Priority:

Keywords:

InRadar

Version:

WebKit Nightly Build

Hardware:

Unspecified

OS:

Unspecified

See Also:

https://bugs.webkit.org/show_bug.cgi?id=189122
https://bugs.webkit.org/show_bug.cgi?id=189123

Bug Depends on:

Bug Blocks:

176199, 189202

Attachments:

Description	Flags
WIP	none
WIP	none
WIP	none
WIP	none

Myles C. Maxfield

Reported 2018-08-29 16:36:49 PDT

Implement dynamically uniform expression restrictions

Attachments
WIP (43.56 KB, patch) 2018-10-04 19:47 PDT, Myles C. Maxfield	no flags	Details Formatted Diff Diff
WIP (49.71 KB, patch) 2018-10-05 19:35 PDT, Myles C. Maxfield	no flags	Details Formatted Diff Diff
WIP (79.07 KB, patch) 2018-10-09 00:07 PDT, Myles C. Maxfield	no flags	Details Formatted Diff Diff
WIP (79.33 KB, patch) 2018-10-09 00:25 PDT, Myles C. Maxfield	no flags	Details Formatted Diff Diff
Show Obsolete (3) View All Add attachment proposed patch, testcase, etc.

Radar WebKit Bug Importer

Comment 1 2018-09-12 18:50:51 PDT

<rdar://problem/44403002>

Myles C. Maxfield

Comment 2 2018-09-24 10:37:06 PDT

Ever value (lvalue and rvalue) will be associated with a "uniformity" attribute, which will be assigned by the compiler. These attributes can even survive being assigned to a variable, if the variable is marked as "uniform" in the program source. Then, after we know whether or not each value is uniform, we can associate each nested scope with a similar uniformity attribute. This is true iff the condition leading to that scope is uniform. We apply the restriction that any AssignmentExpression inside a non-uniform scope must never assign to a uniform variable that is declared in the non-innermost scope. This should guarantee that all uniform variables are, indeed, uniform. Then, we can require any IndexExpression that indexes into an array which contains textures to use a uniform index.

Myles C. Maxfield

Comment 3 2018-09-24 11:14:24 PDT

Functions that return uniform variables must only have a single return point

Myles C. Maxfield

Comment 4 2018-09-24 11:18:09 PDT

UAVs can't hold uniform values

Myles C. Maxfield

Comment 5 2018-09-24 11:25:41 PDT

Conditional continues and breaks should contribute to the uniformity of the blocks they target

Myles C. Maxfield

Comment 6 2018-09-24 11:28:16 PDT

(In reply to Myles C. Maxfield from comment #5) > Conditional continues and breaks should contribute to the uniformity of the > blocks they target This isn't quite right - the continue & break can affect just the remainder of the scope. Also, uniforms should only exist in thread / constant address space.

Myles C. Maxfield

Comment 7 2018-09-24 11:37:48 PDT

(In reply to Myles C. Maxfield from comment #6) > (In reply to Myles C. Maxfield from comment #5) > > Conditional continues and breaks should contribute to the uniformity of the > > blocks they target > > This isn't quite right - the continue & break can affect just the remainder > of the scope. > and "return" In general, returns should be modeled as an assignment to a variable that's outside the function scope.

Myles C. Maxfield

Comment 8 2018-09-24 11:41:52 PDT

(In reply to Myles C. Maxfield from comment #3) > Functions that return uniform variables must only have a single return point Actually, we can do better - just treat early returns as marking the rest of the scope non-uniform, and treating the return as writing to a value that's outside the scope

Myles C. Maxfield

Comment 9 2018-10-04 19:45:53 PDT

*** Bug 189123 has been marked as a duplicate of this bug. ***

Myles C. Maxfield

Comment 10 2018-10-04 19:47:32 PDT

Created attachment 351650 [details] WIP

Myles C. Maxfield

Comment 11 2018-10-05 19:35:24 PDT

Created attachment 351711 [details] WIP

Myles C. Maxfield

Comment 12 2018-10-09 00:07:01 PDT

Created attachment 351866 [details] WIP