Shader Instructions 2-3 times more in 5.1

Development Rendering
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Hey, you can actually find information about this here: Unreal Engine 5.1 Release Notes | Unreal Engine 5.1 Documentation

Here are some information and quotes about it. Basically Epic has set the Default Shader Model for Unreal Engine to 6 instead of 5. Along with this they have resolved some other issues regarding the instruction count:

  • DirectX 12 with Shader Model 6 is Default on PC for New Projects
  • Set InstructionCount when compiling shaders with DXC, which fixes an issue where all compiles of SM6 shaders were reporting 0 instructions.
  • Fix an issue with ‘GetMaxNumInstructionsForShader’ that reported the incorrect instruction count for the given shader type. The function was not checking to see if the shader type in the pipeline was the same as the shader type we are asking for.

Note: The shader count has never been properly counted. If it was compared to the assembly code it would always differ somewhat. Although, this is something I haven’t been able to verify myself to be true or false.

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