Change a byte[] in KnownColorTable to be ReadOnlySpan<byte>

[stephentoub]

cc: @safern

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Issue Details

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cc: @safern

Author:	stephentoub
Assignees:	-
Labels:	area-System.Drawing
Milestone:	-

[safern]

Curious did you find this in auditing memory on some app or anything?

Should we also update s_colorValueTable to ReadOnlySpan<uint> or that doesn't help?

[gfoidl]

Should we also update s_colorValueTable to ReadOnlySpan<uint> or that doesn't help?

This doesn't help. The C# compiler's optimization to refer to the data-segment of the assembly directly only works for (primitive) types with one byte size (due to endianess concerns). See e.g. this sharplab.

[stephentoub]

We'll need #24961 and Roslyn support for it before we can start using this with types other than byte, sbyte, and bool.

[stephentoub]

Curious did you find this in auditing memory on some app or anything?

I was going back through some PRs I hadn't reviewed and saw the array rather than span being introduced in #50489.