microsoft / microsoft/DirectXShaderCompiler

[SPIR-V] OpCopyLogical with same Result and Operand Type for arrays in cbuffer

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bug spirv
Dominant language
C++
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Description

When compiling a cbuffer with an array, an invalid OpCopyLogical instruction is generated where the result type is the same as the operand type.

HLSL Source:

    cbuffer CBArrays : register(b0) {
      float c1[2];
      int4 c2[2][2];
      bool c3[2];
    }
    
    struct Arrays {
      float c1[2];
      int4 c2[2][2];
     bool c3[2];
   };
   
   RWStructuredBuffer<Arrays> Out : register(u1);
   
   [numthreads(1,1,1)]
   void main() {
     Out[0].c1 = c1;
     Out[0].c2 = c2;
     Out[0].c3 = c3;
   }

Compilation Command:

dxc -spirv -fspv-target-env=vulkan1.3 -fvk-use-dx-layout -T cs_6_5 source.hlsl

Error:

   fatal error: generated SPIR-V is invalid: Result Type must not equal the Operand type
     %41 = OpCopyLogical %_arr__arr_v4int_uint_2_uint_2 %39

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the issue with the supplied HLSL source and the dxc SPIR-V compilation command, then inspect the generated OpCopyLogical instruction for the nested array assignment. Done means the compiler no longer emits an OpCopyLogical whose result type equals its operand type, and the generated SPIR-V passes validation.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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