[llvm] [SPIRV]Added support for extension SPV_INTEL_arbitrary_precision_fixed_point (PR #136085)

[Dmitry Sidorov via llvm-commits]

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@@ -213,6 +213,8 @@ list of supported SPIR-V extensions, sorted alphabetically by their extension na
      - Adds a bitwise instruction on three operands and a look-up table index for specifying the bitwise operation to perform. 
    * - ``SPV_INTEL_subgroup_matrix_multiply_accumulate``
      - Adds an instruction to compute the matrix product of an M x K matrix with a K x N matrix and then add an M x N matrix. 
+   * - ``SPV_INTEL_arbitrary_precision_fixed_point``
+     - Works without SPV_INTEL_arbitrary_precision_integers, but together they allow greater flexibility in representing arbitrary precision data types.
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MrSidims wrote:

What about:
```suggestion
     - Add instructions for fixed point arithmetic. The extension works without SPV_INTEL_arbitrary_precision_integers, but together they allow greater flexibility in representing arbitrary precision data types.
```
?

https://github.com/llvm/llvm-project/pull/136085