modify graph optimization pass and LLVMIR gen to fuse 2 or more TFC operators together

Reviewed By: junhanh

Differential Revision: D53798649

fbshipit-source-id: ce5cbf7acf63f6eae4b720ddb537ab9668c7940e

Author: Ryan Xia

include/glow/Graph/FXIRUtils.h

@@ -119,6 +119,8 @@ ElemKind getNodeDataType(const folly::dynamic &node, int idx = -1);
 
 bool hasFxOutTensorView(const folly::dynamic &node);
 
+int countFxOutTensorView(const folly::dynamic &node);
+
 /// Get out tensorview for \p node. If \p idx is non-negative then assume this
 /// is a multi-output node, so get the tensorview output for that specific idx.
 /// \p idx represents which output to get a result for in the case that the node

lib/Graph/FXIRUtils.cpp

@@ -143,6 +143,19 @@ bool glow::hasFxOutTensorView(const folly::dynamic &node) {
   return kwargs.find("out_memref") != kwargs.items().end();
 }
 
+int glow::countFxOutTensorView(const folly::dynamic &node) {
+  const auto &kwargs = getNodeKwargs(node);
+  if (!hasFxOutTensorView(node)) {
+    return 0;
+  }
+  const auto &out = kwargs["out_memref"];
+  if (out.isObject()) {
+    return 1;
+  }
+  CHECK(out.isArray()) << "Expected Node array given multi-output Node";
+  return out.size();
+}
+
 const folly::dynamic &glow::getFxOutTensorView(const folly::dynamic &node,
                                                int idx) {
   const auto &kwargs = getNodeKwargs(node);