findReductions: extract out isReductionUpdate

This function will be reused in the next commit.

Author: Sven Verdoolaege

tc/core/halide2isl.cc

@@ -334,6 +334,14 @@ std::pair<isl::union_map, isl::union_map> extractAccesses(
   return {finder.reads, finder.writes};
 }
 
+bool isReductionUpdate(const Provide* op) {
+  if (const Call* call = op->values[0].as<Call>()) {
+    return call->is_intrinsic(tc2halide::kReductionUpdate);
+  } else {
+    return false;
+  }
+}
+
 /*
  * Take a parametric expression "f" and convert it into an expression
  * on the iteration domains in "domain" by reinterpreting the parameters
@@ -488,14 +496,6 @@ std::vector<Reduction> findReductions(const Stmt& s) {
   class FindReductions : public IRVisitor {
     using IRVisitor::visit;
 
-    bool isReductionUpdate(const Provide* op) {
-      if (const Call* call = op->values[0].as<Call>()) {
-        return call->is_intrinsic(tc2halide::kReductionUpdate);
-      } else {
-        return false;
-      }
-    }
-
     // Keep track of any reduction variable name for use in visit(Provide*)
     void visit(const Variable* op) {
       if (op->reduction_domain.defined()) {