Variadic callables and typing them in func dialect

MLIR
1

Given a trivial example here:

func.func private @apply(%f: (i32) -> i32, %x : i32) -> i32

func.func @double(%x : i32) -> i32 {
  %0 = llvm.mlir.constant(2 : i32) : i32
  %1 = arith.muli %x, %0 : i32
  llvm.return %1 : i32
}

func.func @main() {
  %f = func.constant @double : (i32) -> i32
  %x = arith.constant 5 : i32
  %result = func.call @apply(%f, %x) : ((i32) -> i32, i32) -> i32
  llvm.return
}

Is there a way to generalize @apply so that it binds on any callable that takes arbitrarily typed variadic arguments?

The documentation on func dialect operations itself is minimal and doesn’t seem to address variadics that much, hence this post.

Note that the functions I want to use @apply on aren’t variadic themselves, but may each have different signatures.

One can’t seem to write func.func private @apply(%f: (...) -> i32, ...) -> i32 or anything similar to that.

2

We haven’t spent much time on variadic and/or indirect functions. This probably requires extending the func dialect, which in turn requires an RFC.