[SPIR-V] fatal error: generated SPIR-V is invalid: The <id> passed to OpAccessChain to index into a structure must be an OpConstant

[Sanakan8472]

Hi, As instructed by the compiler, I'm creating a ticket: Command: dxc.exe test.hlsl -spirv -T vs_6_6 -E main -fvk-use-dx-layout -fspv-target-env=vulkan1.1 -Fo ps.out Output:

fatal error: generated SPIR-V is invalid: The <id> passed to OpAccessChain to index into a structure must be an OpConstant.
  %16 = OpLoad %uint %gl_VertexIndex

Used latest build artifact at time of writing. Git commit: 3082ec4a0fa2c4988ba7ee6e3040760850ede98c

Repro Code:

cbuffer TestPositions : register(b3)
{
  float4 Vertex0;
  float4 Vertex1;
  float4 Vertex2;
};

struct VS_OUT
{
  float4 Position : SV_Position;
};

VS_OUT main(uint vertexId : SV_VertexID)
{
  const float4 positions[] = {
    Vertex0,
    Vertex1,
    Vertex2
  };

  VS_OUT RetVal;
  RetVal.Position = positions[vertexId];
  return RetVal;
}

[BarabasGitHub]

Got the same using

struct Rectangle
{
    float2 extent;
    float2 rotation; // complex
    float3 center; // last is depth
    float4 colour;
    float2 uv_min;
    float2 uv_max;
};

ConstantBuffer<Rectangle> g_rectangles[] : register(b2, space1);

float4 main(uint vertex_index : SV_VertexID, uint instance_index : SV_InstanceID)
{
    return CreateRectangleVertex(vertex_index, g_rectangles[instance_index]);
}

command line options: -HV 2021 -WX -spirv -fspv-extension=SPV_EXT_descriptor_indexing -E main -I./ -T vs_6_0

error message:

1>CUSTOMBUILD : fatal error : generated SPIR-V is invalid: OpAccessChain result type (OpTypeStruct) does not match the type that results from indexing into the base <id> (OpTypeStruct).
1>  %51 = OpAccessChain %_ptr_Uniform_ConstantBuffer %g_rectangles %50
1>
1>note: please file a bug report on https://github.com/Microsoft/DirectXShaderCompiler/issues with source code if possible
1>

[Keenuts]

Hello all!

Can reproduce at 7a45cbbf8bab340d212d72c3cfe9f8c5f5837ccf on linux. Will investigate.

[Keenuts]

This issue is caused by SPIRV-Tools optimizer. Root cause found and fix found. However I need to solve another bug before being able to submit this fix.