[clang] [llvm] [SPIRV] Add support for the `SPV_EXT_long_vector` extension (PR #210279)

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github-actions[bot] wrote:

<!--LLVM CODE FORMAT COMMENT: {undef deprecator}-->


:warning: undef deprecator found issues in your code. :warning:

<details>
<summary>
You can test this locally with the following command:
</summary>

``````````bash
git diff -U0 --pickaxe-regex -S '([^a-zA-Z0-9#_-]undef([^a-zA-Z0-9_-]|$)|UndefValue::get)' 'HEAD~1' HEAD llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/bool-vector-bitcast.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/ctpop.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/getelementptr-vector-index.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/integer-casts.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/add.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/and.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/fadd.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/fmax.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/fmaximum.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/fmin.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/fminimum.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/fmul.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/mul.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/or.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/smax.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/smin.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/umax.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/umin.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/llvm-vector-reduce/xor.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/phi-large-vector.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/ptrmask-vec.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/single-element-vector-nested-aggregate.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/single-element-vector.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/spv-extractelt-legalization.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/unmerge-crash-0.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/unmerge-crash-1.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/vector-arithmetic.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/vector-index-scalarization.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/vector-legalization-kernel.ll llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/vector-of-pointers-gep.ll llvm/lib/Target/SPIRV/SPIRVBuiltins.cpp llvm/lib/Target/SPIRV/SPIRVCombinerHelper.cpp llvm/lib/Target/SPIRV/SPIRVCommandLine.cpp llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.h llvm/lib/Target/SPIRV/SPIRVISelLowering.cpp llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp llvm/lib/Target/SPIRV/SPIRVLegalizePointerCast.cpp llvm/lib/Target/SPIRV/SPIRVLegalizerInfo.cpp llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp llvm/lib/Target/SPIRV/SPIRVPostLegalizer.cpp llvm/lib/Target/SPIRV/SPIRVUtils.cpp llvm/lib/Target/SPIRV/SPIRVUtils.h
``````````

</details>


The following files introduce new uses of undef:
 - llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/ctpop.ll
 - llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/unmerge-crash-0.ll
 - llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_long_vector/unmerge-crash-1.ll

[Undef](https://llvm.org/docs/LangRef.html#undefined-values) is now deprecated and should only be used in the rare cases where no replacement is possible. For example, a load of uninitialized memory yields `undef`. You should use `poison` values for placeholders instead.

In tests, avoid using `undef` and having tests that trigger undefined behavior. If you need an operand with some unimportant value, you can add a new argument to the function and use that instead.

For example, this is considered a bad practice:
```llvm
define void @fn() {
  ...
  br i1 undef, ...
}
```

Please use the following instead:
```llvm
define void @fn(i1 %cond) {
  ...
  br i1 %cond, ...
}
```

Please refer to the [Undefined Behavior Manual](https://llvm.org/docs/UndefinedBehavior.html) for more information.



https://github.com/llvm/llvm-project/pull/210279