[llvm] [SPIR-V] Initial implementation of SPV_INTEL_long_composites (PR #126545)

[Vyacheslav Levytskyy via llvm-commits]

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+; RUN: llc -verify-machineinstrs -O0 -mtriple=spirv32-unknown-unknown --spirv-ext=+SPV_INTEL_long_composites %s -o - | FileCheck %s
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VyacheslavLevytskyy wrote:

Probably it would be better to clean the test case of irrelevant details, like lifestart/stop and metadata, just to deliver a clean "long struct to spir-v" check.

https://github.com/llvm/llvm-project/pull/126545