After the work in a538d1f13a13 5351878ba196 372240dfe3d5, and
subsequently cleanup of all the in-tree targets, we can now delete the
support for positional operand matching!
This removes three options which could previously be set in a
Target's "InstrInfo" tablegen definition:
- useDeprecatedPositionallyEncodedOperands
- decodePositionallyEncodedOperands
- noNamedPositionallyEncodedOperands
(Also announced at https://discourse.llvm.org/t/tablegen-deleting-deprecated-positional-instruction-operand-matching-support/68524)
Differential Revision: https://reviews.llvm.org/D144210
Summary:
The existing undefined-bitfield-to-operand matching behavior is very
hard to understand, due to the combination of positional and named
matching. This can make it difficult to track down a bug in a target's
instruction definitions.
Over the last decade, folks have tried to work-around this in various
ways, but it's time to finally ditch the positional matching. With
https://reviews.llvm.org/D131003, there are no longer cases that
_require_ positional matching, and it's time to start removing usage
and support for it.
Therefore: add a (default-false) option, and set it to true only in
those targets that require positional matching today. Subsequent
changes will start cleaning up additional in-tree targets.
NOTE TO OUT OF TREE TARGET MAINTAINERS:
If this change breaks your build, you may restore the previous
behavior simply by adding:
let useDeprecatedPositionallyEncodedOperands = 1;
to your target's InstrInfo tablegen definition. However, this is
temporary -- the option will be removed in the future.
If your target does not set 'decodePositionallyEncodedOperands', you
may thus start migrating to named operands. However, if you _do_
currently set that option, I recommend waiting until a subsequent
change lands, which adds decoder support for named sub-operands.
Differential Revision: https://reviews.llvm.org/D134073
