- Extract code for sorting and checking duplicate Records into a helper
function and update `collectProcModels` to use the helper.
- Update `FeatureKeyValues` to:
(a) Remove code for duplicate checks and use the helper.
(b) Trim features with empty name explicitly to be able to use
the helper.
- Make the sorting deterministic by using record name as a secondary
key for sorting, and re-enable SubtargetFeatureUniqueNames.td test
that was disabled due to the non-determinism of the error messages.
- Change wording of error message when duplicate records are found to
be source code position agnostic, since `First` may not be before
`Second` lexically.
- This test was reported as failing in ASAN builds, with
non-deterministic order of the error message and note expected.
- This is due to llvm::sort() being unstable.
- Temporarily disable the test while its been fixed.
- Keep track of last definition of a feature in a `DenseMap` and use
it to report a better error message when a duplicate feature is found.
- Use StringMap instead of a std::map in `EmitStageAndOperandCycleData`
- Add a unit test to check if duplicate names are flagged.
