[llvm] [SPIR-V] Support SPV_INTEL_fp_max_error extension for `!fpmath` metadata (PR #130619)

[Dmitry Sidorov via llvm-commits]

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@@ -307,6 +309,10 @@ SPIR-V backend, along with their descriptions and argument details.
      - None
      - `[Type, 32-bit Integer, Metadata]`
      - Assigns one of two memory aliasing decorations (specified by the second argument) to instructions using original aliasing metadata node. Not emitted directly but used to support SPIR-V representation in LLVM IR.
+   * - `int_spv_assign_fpmaxerror_decoration`
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MrSidims wrote:

But it is, see: https://llvm.org/doxygen/Instructions_8cpp_source.html#l02682

A valid point would be: llvm ir instruction != mir instruction. Yet during my recent work on aliasing metadata I've found, that there information from aliasing metadata is being transferred to `MachineMemOperand` class and I can access this information in the backend by calling `getAAInfo`. I'm not sure, if it will work, as I'm still a novice in LLVM backend, yet I do see `MO_FPImmediate` enum among `MachineOperandType` class. Can we check, that it (or some other machine operand class) doesn't store accuracy information?

https://github.com/llvm/llvm-project/pull/130619