[spirv-opt] validation failure in spirv-opt eliminate-dead-code-aggressive on slang shader

[jsimmons]

struct Constants {
    uint2 tile_resolution;
    uint *tile_buffer;
}

[shader("compute")]
[numthreads(8, 8, 1)]
void main(uniform Constants constants, uint3 group_id: SV_GroupID) {
    let tile_coord = group_id.xy * WorkgroupSize().xy;
    // Uncomment this and it will compile fine:
    // let hi = constants.tile_buffer[tile_coord.x];
}

compiled with the following command on current main (shader-slang/slang@7e35123)

$ slangc test.slang -target spirv -profile spirv_1_6 -capability vk_mem_model -fvk-use-scalar-layout -fvk-use-entrypoint-name -matrix-layout -row-major -O0 -g -o test.spv

produces spirv which passes spirv-val, however, spirv-opt fails validation during a dce pass.

$ spirv-opt --validate-after-all -O test.spv -o test-opt.spv
error: line 115: ID '85[%85]' has not been defined
  %137 = OpCompositeExtract %v2uint %85 0

error: line 0: Validation failed after pass eliminate-dead-code-aggressive

where spirv-opt is SPIRV-Tools v2025.4 v2025.4-0-g7f2d9ee92

the spirv generated is as follows

; SPIR-V
; Version: 1.6
; Generator: Khronos Slang Compiler; 0
; Bound: 102
; Schema: 0
               OpCapability PhysicalStorageBufferAddresses
               OpCapability Shader
               OpCapability VulkanMemoryModel
               OpCapability VulkanMemoryModelDeviceScope
               OpExtension "SPV_KHR_non_semantic_info"
               OpExtension "SPV_KHR_physical_storage_buffer"
               OpExtension "SPV_KHR_vulkan_memory_model"
          %2 = OpExtInstImport "NonSemantic.Shader.DebugInfo.100"
               OpMemoryModel PhysicalStorageBuffer64 Vulkan
               OpEntryPoint GLCompute %main "main" %entryPointParams %gl_WorkGroupID
               OpExecutionMode %main LocalSize 8 8 1
          %1 = OpString "struct Constants {
    uint2 tile_resolution;
    uint *tile_buffer;
}

[shader(\"compute\")]
[numthreads(8, 8, 1)]
void main(uniform Constants constants, uint3 group_id: SV_GroupID) {
    let tile_coord = group_id.xy * WorkgroupSize().xy;
    // Uncomment this and it will compile fine:
    // let hi = constants.tile_buffer[tile_coord.x];
}
"
          %5 = OpString "/home/josh/Projects/narcissus/test.slang"
               OpSource Slang 1
         %27 = OpString "main"
         %33 = OpString "slangc"
         %34 = OpString "-target spirv  -I \"/home/josh/Projects/slang/build/Debug/bin\" -fvk-use-entrypoint-name -matrix-layout-row-major -O0 -capability vk_mem_model -force-glsl-scalar-layout -stage compute -entry main -g2"
         %36 = OpString "uint"
         %42 = OpString "group_id"
         %52 = OpString "tile_resolution"
         %58 = OpString "tile_buffer"
         %60 = OpString "Constants"
         %63 = OpString "constants"
         %72 = OpString "Constants_natural"
         %75 = OpString "EntryPointParams_natural"
         %77 = OpString "entryPointParams"
         %98 = OpString "tile_coord"
               OpName %_dbgvar_group_id "_dbgvar_group_id"
               OpName %Constants "Constants"
               OpMemberName %Constants 0 "tile_resolution"
               OpMemberName %Constants 1 "tile_buffer"
               OpName %_dbgvar_constants "_dbgvar_constants"
               OpName %_dbgvar_tile_coord "_dbgvar_tile_coord"
               OpName %group_id "group_id"
               OpName %constants "constants"
               OpName %Constants_natural "Constants_natural"
               OpMemberName %Constants_natural 0 "tile_resolution"
               OpMemberName %Constants_natural 1 "tile_buffer"
               OpName %EntryPointParams_natural "EntryPointParams_natural"
               OpMemberName %EntryPointParams_natural 0 "constants"
               OpName %entryPointParams "entryPointParams"
               OpName %tile_coord "tile_coord"
               OpName %main "main"
               OpDecorate %_ptr_PhysicalStorageBuffer_uint ArrayStride 4
               OpDecorate %gl_WorkGroupID BuiltIn WorkgroupId
               OpMemberDecorate %Constants_natural 0 Offset 0
               OpMemberDecorate %Constants_natural 1 Offset 8
               OpDecorate %EntryPointParams_natural Block
               OpMemberDecorate %EntryPointParams_natural 0 Offset 0
       %void = OpTypeVoid
          %4 = OpExtInst %void %2 DebugSource %5 %1
       %uint = OpTypeInt 32 0
    %uint_11 = OpConstant %uint 11
     %uint_5 = OpConstant %uint 5
   %uint_100 = OpConstant %uint 100
         %10 = OpExtInst %void %2 DebugCompilationUnit %uint_100 %uint_5 %4 %uint_11
         %12 = OpTypeFunction %void
     %v3uint = OpTypeVector %uint 3
%_ptr_Function_v3uint = OpTypePointer Function %v3uint
     %v2uint = OpTypeVector %uint 2
%_ptr_PhysicalStorageBuffer_uint = OpTypePointer PhysicalStorageBuffer %uint
  %Constants = OpTypeStruct %v2uint %_ptr_PhysicalStorageBuffer_uint
%_ptr_Function_Constants = OpTypePointer Function %Constants
%_ptr_Function_v2uint = OpTypePointer Function %v2uint
     %uint_0 = OpConstant %uint 0
         %24 = OpExtInst %void %2 DebugTypeFunction %uint_0 %void
     %uint_8 = OpConstant %uint 8
     %uint_6 = OpConstant %uint 6
         %26 = OpExtInst %void %2 DebugFunction %27 %24 %4 %uint_8 %uint_6 %10 %27 %uint_0 %uint_8
         %32 = OpExtInst %void %2 DebugEntryPoint %26 %10 %33 %34
    %uint_32 = OpConstant %uint 32
%uint_131072 = OpConstant %uint 131072
         %35 = OpExtInst %void %2 DebugTypeBasic %36 %uint_32 %uint_6 %uint_131072
     %uint_3 = OpConstant %uint 3
         %39 = OpExtInst %void %2 DebugTypeVector %35 %uint_3
     %uint_2 = OpConstant %uint 2
   %group_id = OpExtInst %void %2 DebugLocalVariable %42 %39 %4 %uint_8 %uint_6 %26 %uint_0 %uint_2
         %44 = OpExtInst %void %2 DebugExpression
%_ptr_Input_v3uint = OpTypePointer Input %v3uint
         %50 = OpExtInst %void %2 DebugTypeVector %35 %uint_2
     %uint_1 = OpConstant %uint 1
    %uint_64 = OpConstant %uint 64
         %51 = OpExtInst %void %2 DebugTypeMember %52 %50 %4 %uint_1 %uint_8 %uint_0 %uint_64 %uint_0
  %uint_5349 = OpConstant %uint 5349
         %55 = OpExtInst %void %2 DebugTypePointer %35 %uint_5349 %uint_131072
         %57 = OpExtInst %void %2 DebugTypeMember %58 %55 %4 %uint_1 %uint_8 %uint_64 %uint_64 %uint_0
   %uint_128 = OpConstant %uint 128
         %59 = OpExtInst %void %2 DebugTypeComposite %60 %uint_1 %4 %uint_1 %uint_8 %10 %60 %uint_128 %uint_131072 %51 %57
  %constants = OpExtInst %void %2 DebugLocalVariable %63 %59 %4 %uint_8 %uint_6 %26 %uint_0 %uint_1
%Constants_natural = OpTypeStruct %v2uint %_ptr_PhysicalStorageBuffer_uint
%EntryPointParams_natural = OpTypeStruct %Constants_natural
%_ptr_PushConstant_EntryPointParams_natural = OpTypePointer PushConstant %EntryPointParams_natural
         %69 = OpExtInst %void %2 DebugTypeMember %52 %50 %4 %uint_0 %uint_0 %uint_0 %uint_64 %uint_0
         %70 = OpExtInst %void %2 DebugTypeMember %58 %55 %4 %uint_0 %uint_0 %uint_64 %uint_64 %uint_0
         %71 = OpExtInst %void %2 DebugTypeComposite %72 %uint_1 %4 %uint_0 %uint_0 %10 %72 %uint_128 %uint_131072 %69 %70
         %73 = OpExtInst %void %2 DebugTypeMember %63 %71 %4 %uint_0 %uint_0 %uint_0 %uint_128 %uint_0
         %74 = OpExtInst %void %2 DebugTypeComposite %75 %uint_1 %4 %uint_0 %uint_0 %10 %75 %uint_128 %uint_131072 %73
        %int = OpTypeInt 32 1
      %int_0 = OpConstant %int 0
%_ptr_PushConstant_Constants_natural = OpTypePointer PushConstant %Constants_natural
     %uint_9 = OpConstant %uint 9
      %v2int = OpTypeVector %int 2
      %int_8 = OpConstant %int 8
         %94 = OpConstantComposite %v2int %int_8 %int_8
 %tile_coord = OpExtInst %void %2 DebugLocalVariable %98 %50 %4 %uint_9 %uint_9 %26 %uint_0
%gl_WorkGroupID = OpVariable %_ptr_Input_v3uint Input
%entryPointParams = OpVariable %_ptr_PushConstant_EntryPointParams_natural PushConstant
         %76 = OpExtInst %void %2 DebugGlobalVariable %77 %74 %4 %uint_0 %uint_0 %10 %77 %entryPointParams %uint_0
       %main = OpFunction %void None %12
         %13 = OpLabel
%_dbgvar_group_id = OpVariable %_ptr_Function_v3uint Function
%_dbgvar_constants = OpVariable %_ptr_Function_Constants Function
%_dbgvar_tile_coord = OpVariable %_ptr_Function_v2uint Function
         %30 = OpExtInst %void %2 DebugFunctionDefinition %26 %main
         %31 = OpExtInst %void %2 DebugScope %26
         %45 = OpExtInst %void %2 DebugDeclare %group_id %_dbgvar_group_id %44
         %46 = OpLoad %v3uint %gl_WorkGroupID
               OpStore %_dbgvar_group_id %46
         %64 = OpExtInst %void %2 DebugDeclare %constants %_dbgvar_constants %44
         %81 = OpAccessChain %_ptr_PushConstant_Constants_natural %entryPointParams %int_0
         %82 = OpLoad %Constants_natural %81
         %83 = OpCompositeExtract %v2uint %82 0
         %84 = OpCompositeExtract %_ptr_PhysicalStorageBuffer_uint %82 1
         %85 = OpCompositeConstruct %Constants %83 %84
               OpStore %_dbgvar_constants %85
         %87 = OpLoad %v3uint %gl_WorkGroupID
         %88 = OpExtInst %void %2 DebugLine %4 %uint_9 %uint_9 %uint_5 %uint_6
         %90 = OpExtInst %void %2 DebugLine %4 %uint_9 %uint_9 %uint_5 %uint_6
         %91 = OpVectorShuffle %v2uint %87 %87 0 1
         %92 = OpBitcast %v2uint %94
         %96 = OpIMul %v2uint %91 %92
         %99 = OpExtInst %void %2 DebugDeclare %tile_coord %_dbgvar_tile_coord %44
               OpStore %_dbgvar_tile_coord %96
               OpReturn
               OpFunctionEnd

[s-perron]

I'm guessing this will be fixed by #6368. At some point can you verify? I was not able to reproduce exactly what you saw, but I can an assert with a debug build that seem similar. That goes away with #6368.