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

```slang
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 (https://github.com/shader-slang/slang/commit/7e35123bae1cd3b032fdffcafd600aa78394bf2d)

```
$ 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

```spirv
; 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
```

Start by reproducing the failure with the supplied test.slang, slangc command, and spirv-opt --validate-after-all -O invocation. Inspect the eliminate-dead-code-aggressive pass using the generated SPIR-V around the undefined %85 and verify that optimization completes with validation enabled and produces valid output.

Written by the indexing model from the issue text.