[clang] [CIR] Upstream StackSave and StackRestoreOp (PR #136426)

[Bruno Cardoso Lopes via cfe-commits]

https://github.com/bcardosolopes approved this pull request.

The PR looks good overall, it adds the operation, tests for parsing/printing + LLVM lowering, leaving CIRGen to support to be done incrementally. LGTM once the operation names are used consistently.

https://github.com/llvm/llvm-project/pull/136426