[mlir] Move FunctionInterfaces to Interfaces directory and inherit from CallableOpInterface

Functions are always callable operations and thus every operation
implementing the `FunctionOpInterface` also implements the
`CallableOpInterface`. The only exception was the FuncOp in the toy
example. To make implementation of the `FunctionOpInterface` easier,
this commit lets `FunctionOpInterface` inherit from
`CallableOpInterface` and merges some of their methods. More precisely,
the `CallableOpInterface` has methods to get the argument and result
attributes and a method to get the result types of the callable region.
These methods are always implemented the same way as their analogues in
`FunctionOpInterface` and thus this commit moves all the argument and
result attribute handling methods to the callable interface as well as
the methods to get the argument and result types. The
`FuntionOpInterface` then does not have to declare them as well, but
just inherits them from the `CallableOpInterface`.
Adding the inheritance relation also required to move the
`FunctionOpInterface` from the IR directory to the Interfaces directory
since IR should not depend on Interfaces.

Reviewed By: jpienaar, springerm

Differential Revision: https://reviews.llvm.org/D157988

1 files changed, 1 insertions, 1 deletions

diff --git a/mlir/lib/Dialect/MLProgram/IR/MLProgramOps.cpp b/mlir/lib/Dialect/MLProgram/IR/MLProgramOps.cpp
index 31ed5ad3b987..f8f754956603 100644
--- a/mlir/lib/Dialect/MLProgram/IR/MLProgramOps.cpp
+++ b/mlir/lib/Dialect/MLProgram/IR/MLProgramOps.cpp
@@ -8,7 +8,7 @@
 
 #include "mlir/Dialect/MLProgram/IR/MLProgram.h"
 #include "mlir/IR/Builders.h"
-#include "mlir/IR/FunctionImplementation.h"
+#include "mlir/Interfaces/FunctionImplementation.h"
 
 using namespace mlir;
 using namespace mlir::ml_program;