[PATCH] D42251: [globalisel][legalizer] Adapt LegalizerInfo to support inter-type dependencies and other things.

[Daniel Sanders via Phabricator via llvm-commits]

dsanders marked an inline comment as done.
dsanders added inline comments.


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Comment at: include/llvm/CodeGen/GlobalISel/LegalizerInfo.h:348
+        },
+        LegalizeMutations::pick(TypeIdx, Ty));
+  }
----------------
bogner wrote:
> dsanders wrote:
> > reames wrote:
> > > You might want to choose a different verb than "pick" here.  Or at least, it isn't obvious from just reading the code what this does.
> > One of my colleagues has said the same thing in person a couple days ago but I haven't come up with anything better yet. The intent is that it returns a mutation function that always returns the given typeidx and type.
> I'd probably just go with "identity". It's not great, but I think it's clearer/more precise than pick.
Ok, I'll go with identity for now but we ought to come up with a better name still. `identity()` makes it sound like you get a mutator that doesn't change anything but that's not correct. You get a mutator that changes the type to a specific type.

For example, given:
   LegalityQuery({G_ADD, {s32})
the rule:
  .widenScalarIf(typeInSet(0, {s32}), identity(0, s64))
will result in the action:
  {WidenScalar, /*TypeIdx*/0, s64}
which will widen the G_ADD to work on s64's.


https://reviews.llvm.org/D42251