[MIR] Serialize MachineFrameInfo::isCalleeSavedInfoValid()

[dtellenbach]

In case of functions without a stack frame no "stack" field is serialized into MIR which leads to isCalleeSavedInfoValid being false when reading a MIR file back in. To fix this we should serialize MachineFrameInfo::isCalleeSavedInfoValid() into MIR.

[arsenm]

Needs a parsing test where this is true. Can you also add one that hit the issue you described? Can we just print the empty list in this case?

[dtellenbach]

Can we just print the empty list in this case?

That wouldn't help because the logic in MIRParser would still not find any callee-saved info and set it as not valid.

[francisvm]

Can we just print the empty list in this case?

That wouldn't help because the logic in MIRParser would still not find any callee-saved info and set it as not valid.

Would an empty stack list, isCalleeSavedInfoValid: true and -run-pass none test the right thing?

[dtellenbach]

Can we just print the empty list in this case?

That wouldn't help because the logic in MIRParser would still not find any callee-saved info and set it as not valid.

Would an empty stack list, isCalleeSavedInfoValid: true and -run-pass none test the right thing?

Oh yes, testing is no issue. I understood the question as can't we omit isCalleeSavedInfoValid when just using an empty stack list.

[dtellenbach]

Added a test that should cover all combinations of having a stack or not and having valid callee-saved info or not.

[dtellenbach]

Sure, the newly added test is failing because llc uses the x86 runner's target triple which doesn't know $lr. Moving to MIR/AArch64 and requiring an arm64 triple.

[francisvm]

LGTM