Vector2.One is not always <1, 1> in some case (silent bad codegen)

[ryancheung]

Reduced repro - Windows x64, repros at commit 9c0bf21 :

1. Compile with optimizations on:

using System;
using System.Numerics;
using System.Runtime.CompilerServices;

t(1, 1, 1, 1, Vector2.One, Vector2.One, Vector2.One, Vector2.One);

[MethodImplAttribute(MethodImplOptions.NoInlining)]
static void t(int a1, int a2, int a3, int a4, Vector2 x1, Vector2 x2, Vector2 x3, Vector2 x4)
{
   if (x1 != Vector2.One) Console.WriteLine("FAIL");
}

2. Run (with COMPlus_TieredCompilation=0)

Actual result:

• Checked build: Assertion failed 'isFloatReg(dstReg) && isFloatReg(srcReg)' in '$:$(System.String[])' during 'Generate code'
• Release build: FAIL

Expected result: passes without asserts or errors

---

I have some code:

        public static void DrawSpriteFrame(this CommandBuffer commandBuffer, SpriteFrame spriteFrame, Vector2 position, Color color, float layerDepth = 0f)
        {
            DrawSpriteFrame(commandBuffer, spriteFrame, position, null, color, Vector2.One, 0f, SpriteEffects.None, layerDepth);
        }

        public static void DrawSpriteFrame(this CommandBuffer commandBuffer, SpriteFrame spriteFrame, Vector2 position, Rectangle areaRewrite, Color color, float layerDepth = 0f)
        {
            DrawSpriteFrame(commandBuffer, spriteFrame, position, areaRewrite, color, Vector2.One, 0f, SpriteEffects.None, layerDepth);
        }

        public static void DrawSpriteFrame(this CommandBuffer commandBuffer, SpriteFrame spriteFrame, Vector2 position, Size sizeRewrite, Color color, float layerDepth = 0f)
        {
            var areaRewrite = new Rectangle(0, 0, sizeRewrite.Width, sizeRewrite.Height);
            DrawSpriteFrame(commandBuffer, spriteFrame, position, areaRewrite, color, Vector2.One, 0f, SpriteEffects.None, layerDepth);
        }

        public static void DrawSpriteFrame(this CommandBuffer commandBuffer, SpriteFrame spriteFrame, Vector2 position, Rectangle? areaRewrite, Color color, Vector2 scale, float rotation = 0f, SpriteEffects spriteEffects = SpriteEffects.None, float layerDepth = 0f)
        {
            if (scale != Vector2.One)
            {
                Console.WriteLine("Scale is: {0}", scale);
                return;
            }
            ...
        }

The Vector2.One passed to method calls is not actually equal to Vector2.One in NativeAOT sometimes. It returns <6.28E-43, 5.27E-43> instead. But everything is fine is CoreCLR. And I'm sure the value of the scale parameter is always <1, 1> in all code logic.

The workaround I found: Change the method call parameter Vector2.One to new Vector2(1, 1).

Which looks like:

        public static void DrawSpriteFrame(this CommandBuffer commandBuffer, SpriteFrame spriteFrame, Vector2 position, Color color, float layerDepth = 0f)
        {
            DrawSpriteFrame(commandBuffer, spriteFrame, position, null, color, new Vector2(1f, 1f), 0f, SpriteEffects.None, layerDepth);
        }

[jkotas]

Any chance you can share a complete test that reproduces the problem?

If you are unable to create a small repro and you are not confortable sharing the application that hits the problem publicily, would you be willing to share it privately? My email address is in my github profile.

[ryancheung]

Yeah, I can sent you a repro sample by email. Wait a moment.

[ryancheung]

@jkotas A repro sample project is sent to you. The vector2-one-issue-repro branch reproduces this issue.

[ryancheung]

BTW, I have tested with old Microsoft.DotNet.ILCompiler preview 3 version and it works fine.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[jkotas]

@ryancheung Thank you for sharing the repro! This is a bug in the current .NET 6 preview builds. I have transfered to dotnet/runtime repo.

[jkotas]

cc @dotnet/jit-contrib

[sandreenko]

Thanks for the repro @ryancheung , I will take a look.