Modernize and optimize pixel format operations across platforms. by JimBobSquarePants · Pull Request #2645 · SixLabors/ImageSharp

JimBobSquarePants · 2024-01-15T04:39:22Z

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I have written a descriptive pull-request title
I have verified that there are no overlapping pull-requests open
I have verified that I am following the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules 👮.
I have provided test coverage for my change (where applicable)

Description

Updates API to use static interface methods for improved usability and extensibility.
Optimizes and modernizes SIMD pixel shuffle operations, adding ARM support.
~~Optimizes and modernizes SIMD Vector4 packing operations.~~ I'm leaving this for a follow up PR

I don't expect anyone to reasonably find the time to analyze this line-by-line as it's a massive piece of work. However, changes on the whole are simplistic and the developer benefit massive.

API change Elevator Pitch

The abomination that is.

TPixel pixel = default;
pixel.FromScaledVector(vector)

Becomes, as nature intended.

TPixel pixel = TPixel.FromScaledVector(vector);

All other conversion methods follow suit where applicable.

JimBobSquarePants · 2024-01-15T04:57:14Z

+    /// <param name="numBytes">The number of bytes to shift by.</param>
+    /// <returns>The <see cref="Vector128{Byte}"/>.</returns>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static Vector128<byte> ShiftRightBytesInVector(Vector128<byte> value, [ConstantExpected(Max = (byte)15)] byte numBytes)


There's something not right in one of the methods below on Arm64.

@tannergooding @saucecontrol Would either of you be able to do a quick readthrough and set me right?

Figured it out. It was left shift. I'd forgotten to offset.

tannergooding · 2024-01-16T14:28:51Z

+    /// Calculates <paramref name="x"/> % 4
+    /// </summary>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static nuint Modulo4(nuint x) => x & 3;


Just noting that x % 4 should already get optimized to x & 3 by the JIT since x is nuint (and therefore definitely unsigned)

Thanks yeah, I just kept it the same for consistency.

tannergooding · 2024-01-16T14:36:46Z

+                    ref Vector512<float> vs0 = ref Unsafe.Add(ref sourceBase, i);
+                    ref Vector512<float> vd0 = ref Unsafe.Add(ref destinationBase, i);

-                    vd0 = Avx.Permute(vs0, control);
-                    Unsafe.Add(ref vd0, 1) = Avx.Permute(Unsafe.Add(ref vs0, 1), control);
-                    Unsafe.Add(ref vd0, 2) = Avx.Permute(Unsafe.Add(ref vs0, 2), control);
-                    Unsafe.Add(ref vd0, 3) = Avx.Permute(Unsafe.Add(ref vs0, 3), control);
+                    vd0 = Vector512Utilities.Shuffle(vs0, control);
+                    Unsafe.Add(ref vd0, (nuint)1) = Vector512Utilities.Shuffle(Unsafe.Add(ref vs0, (nuint)1), control);
+                    Unsafe.Add(ref vd0, (nuint)2) = Vector512Utilities.Shuffle(Unsafe.Add(ref vs0, (nuint)2), control);
+                    Unsafe.Add(ref vd0, (nuint)3) = Vector512Utilities.Shuffle(Unsafe.Add(ref vs0, (nuint)3), control);


Worth noting that you could do this like the following:

Vector512Utilities.Shuffle(Vector512.LoadUnsafe(ref sourceBase, i + 0), control).StoreUnsafe(ref destinationBase, i + 0). Vector512Utilities.Shuffle(Vector512.LoadUnsafe(ref sourceBase, i + 1), control).StoreUnsafe(ref destinationBase, i + 1). Vector512Utilities.Shuffle(Vector512.LoadUnsafe(ref sourceBase, i + 2), control).StoreUnsafe(ref destinationBase, i + 2). Vector512Utilities.Shuffle(Vector512.LoadUnsafe(ref sourceBase, i + 3), control).StoreUnsafe(ref destinationBase, i + 3).

It shouldn't result in any codegen differences, but avoids needing to manipulate the byref and uses direct hardware intrinsic APIs, rather than the Unsafe helpers, so can be easier to read/understand at least IMO.

sourceBase is Vector512<float> so Vector512.LoadUnsafe(ref sourceBase, i + 0) would yield Vector512<Vector512<float>>. I could use float as the base ref type but that complicates the offsetting which confuses me and causes me to make mistakes.

tannergooding

LGTM, just left a couple comments on newer APIs that might help with readability

stefannikolei · 2024-01-20T13:21:08Z

-    /// </summary>
-    /// <returns>The <see cref="PixelTypeInfo"/>.</returns>
-#pragma warning disable CA1000
-    static abstract PixelTypeInfo GetPixelTypeInfo();


Just curious. Is there a specific reason to kick it from the interface and only have it in the implementations? Probably it was never called from the interface and only from specific implementations?

Actually, this is just temporary. I had to hack to get the solution to build because we were misusing ApproximateFloatComparer in the tests.

tannergooding · 2024-01-20T16:14:40Z

  <Include Path="..\shared-infrastructure\sixlabors.ruleset" Action="Default" />
-  <Rules AnalyzerId="StyleCop.Analyzers" RuleNamespace="StyleCop.Analyzers">
+  <Rules AnalyzerId="Microsoft.CodeAnalysis.CSharp.Features" RuleNamespace="Microsoft.CodeAnalysis.CSharp.Features">
+    <Rule Id="IDE0290" Action="None" />


This should also be suppressible via .editorconfig using csharp_style_prefer_primary_constructors = false:none (or a different severity level if you want to block use of primary constructors altogether, such as silent, suggestion, warning, or error)

Thanks. Yeah, I’ll do that upstream. Not sold on primary constructors. The syntax doesn’t sit right with me.

JimBobSquarePants added 3 commits January 13, 2024 10:13

Port shuffle4

3969525

Port first Shuffl3 method

4931372

Introduce new utilities to replace poor performing runtime methods

b250ac3

JimBobSquarePants added API area:pixelformats breaking Signifies a binary breaking change. arch:arm64 labels Jan 15, 2024

JimBobSquarePants added this to the v4.0.0 milestone Jan 15, 2024

Fix missed normalization

4c47a78

JimBobSquarePants commented Jan 15, 2024

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saucecontrol reviewed Jan 15, 2024

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Comment thread src/ImageSharp/Common/Helpers/Vector128Utilities.cs Outdated

JimBobSquarePants added 4 commits January 15, 2024 15:24

Attempt to fix left shift

d9126ea

Push the right fix!

5cf8f60

Use proper constant

c9b4edd

Update individual pixel implementations

acaebd9

tannergooding reviewed Jan 16, 2024

View reviewed changes

tannergooding approved these changes Jan 16, 2024

View reviewed changes

Update library to use new pixel API

dfd983f

stefannikolei reviewed Jan 20, 2024

View reviewed changes

tannergooding reviewed Jan 20, 2024

View reviewed changes

Restore GetPixelTypeInfo

8af75fe

JimBobSquarePants mentioned this pull request Jan 21, 2024

Investigate skipped tests in PackedPixelTests #594

Closed

4 tasks

JimBobSquarePants added 2 commits January 21, 2024 22:04

Update refs

2de4f2c

Merge branch 'main' into js/pixelsformats

cee00af

JimBobSquarePants marked this pull request as ready for review January 21, 2024 12:17

JimBobSquarePants changed the title ~~WIP : Modernize and optimize pixel format operations across platforms.~~ Modernize and optimize pixel format operations across platforms. Jan 21, 2024

JimBobSquarePants requested review from stefannikolei and tocsoft and removed request for stefannikolei January 21, 2024 12:17

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Modernize and optimize pixel format operations across platforms.#2645

Modernize and optimize pixel format operations across platforms.#2645
JimBobSquarePants merged 14 commits into
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API change Elevator Pitch

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