[PATCH] D71474: [TableGen] Introduce an if/then/else statement.

[Nicolai Hähnle via Phabricator via llvm-commits]

nhaehnle added a comment.

I agree with Hal that if/else should introduce a scope. Otherwise, you get into consistency problems. Consider:

  multiclass Foo<...> {
     if ... then {
        defvar bar = ...;
     }
     defvar baz = bar;
  }

Without introducing a scope, the above is presumably valid but in a rather surprising way. And a similar example with an `else` that also defines `bar` wouldn't be valid due to the redefinition.

Generally I'm in favor of this feature, and desugaring it as a loop is a good idea as it should then compose nicely with other features. Some more tests are needed, in particular its use in a multiclass and (negative test) in a def and class.


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https://reviews.llvm.org/D71474