Debug option -g produce incorrect SpirV code

[mklefrancois]

When using the debug -g option, the SpirV code won't pass validation.

The error will look like:

VUID-VkShaderModuleCreateInfo-pCode-08737(ERROR / SPEC): msgNum: -1520283006 - Validation Error: [ VUID-VkShaderModuleCreateInfo-pCode-08737 ] | MessageID = 0xa5625282 | vkCreateShaderModule(): pCreateInfo->pCode (spirv-val produced an error):
NonSemantic.Shader.DebugInfo.100 DebugFunctionDefinition: must be in the entry basic block of the function
  %41 = OpExtInst %void %2 DebugFunctionDefinition %37 %main

[csyonghe]

We will need a shader code to reproduce this issue since this isn't happening for every shader code.

[mklefrancois]

Here is the shader that is causing an issue:
shader_slang.zip

The compilation arguments are

C:/VulkanSDK/1.4.304.0/Bin/slangc.exe
        -profile sm_6_6+spirv_1_6
        -capability spvInt64Atomics+spvShaderInvocationReorderNV+spvShaderClockKHR+spvRayTracingMotionBlurNV
        -target spirv
        -emit-spirv-directly
        -force-glsl-scalar-layout
        -fvk-use-entrypoint-name
        -g3  # Enable debug information
        -source-embed-style text   
        -source-embed-name shader_comp_slang
        shader.comp.slang

[csyonghe]

I can confirm that this is a bug in SPIRV-Opt. If you compile with -O0 (disable spirv-opt), the resulting SPIRV is fine.

[csyonghe]

Bug filed for SPIRV-Tools: #5959

[mklefrancois]

Thanks for the tip! I confirm that when using -g3 -O0 doesn't generate any validation errors.