[MLIR][Affine] Drop assumptions of surrounding builtin.func op in Utils/LoopUtils

Drop assumptions of surrounding builtin.func op in affine LoopUtils and
Utils. There are use cases of affine fusion or affine transformation in
other func-like ops.

Author: bondhugula

mlir/lib/Dialect/Affine/Utils/LoopUtils.cpp

@@ -1936,8 +1936,8 @@ static LogicalResult generateCopy(
   *nBegin = begin;
   *nEnd = end;
 
-  func::FuncOp f = begin->getParentOfType<func::FuncOp>();
-  OpBuilder topBuilder(f.getBody());
+  auto f = begin->getParentOfType<FunctionOpInterface>();
+  OpBuilder topBuilder(f.getFunctionBody());
   Value zeroIndex = topBuilder.create<arith::ConstantIndexOp>(f.getLoc(), 0);
 
   *sizeInBytes = 0;
@@ -1956,8 +1956,9 @@ static LogicalResult generateCopy(
   OpBuilder &b = region.isWrite() ? epilogue : prologue;
 
   // Builder to create constants at the top level.
-  auto func = copyPlacementBlock->getParent()->getParentOfType<func::FuncOp>();
-  OpBuilder top(func.getBody());
+  auto func =
+      copyPlacementBlock->getParent()->getParentOfType<FunctionOpInterface>();
+  OpBuilder top(func.getFunctionBody());
 
   auto loc = region.loc;
   auto memref = region.memref;

mlir/lib/Dialect/Affine/Utils/Utils.cpp

@@ -1391,11 +1391,11 @@ LogicalResult mlir::affine::replaceAllMemRefUsesWith(
   std::unique_ptr<PostDominanceInfo> postDomInfo;
   if (domOpFilter)
     domInfo = std::make_unique<DominanceInfo>(
-        domOpFilter->getParentOfType<func::FuncOp>());
+        domOpFilter->getParentOfType<FunctionOpInterface>());
 
   if (postDomOpFilter)
     postDomInfo = std::make_unique<PostDominanceInfo>(
-        postDomOpFilter->getParentOfType<func::FuncOp>());
+        postDomOpFilter->getParentOfType<FunctionOpInterface>());
 
   // Walk all uses of old memref; collect ops to perform replacement. We use a
   // DenseSet since an operation could potentially have multiple uses of a