This commit generalizes `replaceUsesOfBlockArgument` to
`replaceAllUsesWith`. In rollback mode, the same restrictions keep
applying: a value cannot be replaced multiple times and a call to
`replaceAllUsesWith` will replace all current and future uses of the
`from` value.
`replaceAllUsesWith` is now fully supported and its behavior is
consistent with the remaining dialect conversion API. Before this
commit, `replaceAllUsesWith` was immediately reflected in the IR when
running in rollback mode. After this commit, `replaceAllUsesWith`
changes are materialized in a delayed fashion, at the end of the dialect
conversion. This is consistent with the `replaceUsesOfBlockArgument` and
`replaceOp` APIs.
`replaceAllUsesExcept` etc. are still not supported and will be
deactivated on the `ConversionPatternRewriter` (when running in rollback
mode) in a follow-up commit.
Note for LLVM integration: Replace `replaceUsesOfBlockArgument` with
`replaceAllUsesWith`. If you are seeing failures, you may have patterns
that use `replaceAllUsesWith` incorrectly (e.g., being called multiple
times on the same value) or bypass the rewriter API entirely. E.g., such
failures were mitigated in Flang by switching to the walk-patterns
driver (#156171).
You can temporarily reactivate the old behavior by calling
`RewriterBase::replaceAllUsesWith`. However, note that that behavior is
faulty in a dialect conversion. E.g., the base
`RewriterBase::replaceAllUsesWith` implementation does not see uses of
the `from` value that have not materialized yet and will, therefore, not
replace them.
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