From b2844bb3c905af9879a1fe0151eb57793a7b592a Mon Sep 17 00:00:00 2001
From: Roman Dzhabarov <rdzhabarov@fb.com>
Date: Wed, 12 Jun 2019 11:36:47 -0700
Subject: [PATCH] List all registered backends in case particular backend is
 not found (#3088)

Summary:
Print all backends, improve debuggability in case particular backend is missing.

Documentation:
n/a
Pull Request resolved: https://github.com/pytorch/glow/pull/3088

Differential Revision: D15781780

Pulled By: rdzhabarov

fbshipit-source-id: 5edb63be413dfd934effafcda18f54b7aa41b9df
---
 include/glow/Support/Register.h | 2 +-
 lib/Backends/Backends.cpp       | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/include/glow/Support/Register.h b/include/glow/Support/Register.h
index 402ede10e5..e880c7e2fa 100644
--- a/include/glow/Support/Register.h
+++ b/include/glow/Support/Register.h
@@ -62,7 +62,7 @@ template <class Key, class Base> class FactoryRegistry {
     return it->second->create();
   }
 
-private:
+  /// \returns all registered factories.
   static FactoryMap &factories() {
     static FactoryMap *factories = new FactoryMap();
     return *factories;
diff --git a/lib/Backends/Backends.cpp b/lib/Backends/Backends.cpp
index 8b06861628..4c8aae9fb9 100644
--- a/lib/Backends/Backends.cpp
+++ b/lib/Backends/Backends.cpp
@@ -25,6 +25,14 @@ Backend *createBackend(BackendKind backendKind) {
 
 Backend *createBackend(llvm::StringRef backendName) {
   auto *backend = FactoryRegistry<std::string, Backend>::get(backendName);
+
+  if (backend == nullptr) {
+    LOG(INFO) << "List of all registered backends:";
+    for (const auto &factory :
+         FactoryRegistry<std::string, Backend>::factories()) {
+      LOG(INFO) << factory.first;
+    }
+  }
   CHECK(backend) << strFormat("Cannot find registered backend: %s",
                               backendName.data());
   return backend;