refactor xir atomic inst #3401

Job	Run time
macOS / release / homebrew-clang	4m 41s
Windows / release / msvc	25m 55s
macOS / debug / homebrew-clang	4m 18s
Windows / release / clang-cl	14m 30s
macOS / release / system-clang	3m 44s
Windows / release / llvm	24m 41s
macOS / debug / system-clang	3m 27s
Windows / debug / msvc	22m 31s
Windows / debug / clang-cl	13m 35s
Windows / debug / llvm	15m 20s
	2h 12m 42s

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