[GPU-Plugin] Integration of a faster version of grow_gpu plugin into mainstream (#2360)

* Integrating a faster version of grow_gpu plugin
1. Removed the older files to reduce duplication
2. Moved all of the grow_gpu files under 'exact' folder
3. All of them are inside 'exact' namespace to avoid any conflicts
4. Fixed a bug in benchmark.py while running only 'grow_gpu' plugin
5. Added cub and googletest submodules to ease integration and unit-testing
6. Updates to CMakeLists.txt to directly build cuda objects into libxgboost

* Added support for building gpu plugins through make flow
1. updated makefile and config.mk to add right targets
2. added unit-tests for gpu exact plugin code

* 1. Added support for building gpu plugin using 'make' flow as well
2. Updated instructions for building and testing gpu plugin

* Fix travis-ci errors for PR#2360
1. lint errors on unit-tests
2. removed googletest, instead depended upon dmlc-core provide gtest cache

* Some more fixes to travis-ci lint failures PR#2360

* Added Rory's copyrights to the files containing code from both.

* updated copyright statement as per Rory's request

* moved the static datasets into a script to generate them at runtime

* 1. memory usage print when silent=0
2. tests/ and test/ folder organization
3. removal of the dependency of googletest for just building xgboost
4. coding style updates for .cuh as well

* Fixes for compilation warnings

* add cuda object files as well when JVM_BINDINGS=ON

tests/cpp/data/test_simple_dmatrix.cc

@@ -62,7 +62,7 @@ TEST(SimpleDMatrix, ColAccessWithoutBatches) {
     num_col_batch += 1;
     EXPECT_EQ(col_iter->Value().size, dmat->info().num_col)
       << "Expected batch size = number of cells as #batches is 1.";
-    for (int i = 0; i < col_iter->Value().size; ++i) {
+    for (int i = 0; i < static_cast<int>(col_iter->Value().size); ++i) {
       EXPECT_EQ(col_iter->Value()[i].length, dmat->GetColSize(i))
         << "Expected length of each colbatch = colsize as #batches is 1.";
     }
@@ -106,7 +106,7 @@ TEST(SimpleDMatrix, ColAccessWithBatches) {
     num_col_batch += 1;
     EXPECT_EQ(col_iter->Value().size, dmat->info().num_col)
       << "Expected batch size = num_cols as max_row_perbatch is 1.";
-    for (int i = 0; i < col_iter->Value().size; ++i) {
+    for (int i = 0; i < static_cast<int>(col_iter->Value().size); ++i) {
       EXPECT_LE(col_iter->Value()[i].length, 1)
         << "Expected length of each colbatch <=1 as max_row_perbatch is 1.";
     }

tests/cpp/helpers.cc

@@ -40,7 +40,7 @@ void CheckObjFunction(xgboost::ObjFunction * obj,
   obj->GetGradient(preds, info, 1, &gpair);
 
   ASSERT_EQ(gpair.size(), preds.size());
-  for (int i = 0; i < gpair.size(); ++i) {
+  for (int i = 0; i < static_cast<int>(gpair.size()); ++i) {
     EXPECT_NEAR(gpair[i].grad, out_grad[i], 0.01)
       << "Unexpected grad for pred=" << preds[i] << " label=" << labels[i]
       << " weight=" << weights[i];

tests/cpp/objective/test_regression_obj.cc

@@ -49,7 +49,7 @@ TEST(Objective, LogisticRegressionBasic) {
   std::vector<xgboost::bst_float> preds = {0, 0.1, 0.5, 0.9, 1};
   std::vector<xgboost::bst_float> out_preds = {0.5, 0.524, 0.622, 0.710, 0.731};
   obj->PredTransform(&preds);
-  for (int i = 0; i < preds.size(); ++i) {
+  for (int i = 0; i < static_cast<int>(preds.size()); ++i) {
     EXPECT_NEAR(preds[i], out_preds[i], 0.01);
   }
 }
@@ -97,7 +97,7 @@ TEST(Objective, PoissonRegressionBasic) {
   std::vector<xgboost::bst_float> preds = {0, 0.1, 0.5, 0.9, 1};
   std::vector<xgboost::bst_float> out_preds = {1, 1.10, 1.64, 2.45, 2.71};
   obj->PredTransform(&preds);
-  for (int i = 0; i < preds.size(); ++i) {
+  for (int i = 0; i < static_cast<int>(preds.size()); ++i) {
     EXPECT_NEAR(preds[i], out_preds[i], 0.01);
   }
 }
@@ -132,7 +132,7 @@ TEST(Objective, GammaRegressionBasic) {
   std::vector<xgboost::bst_float> preds = {0, 0.1, 0.5, 0.9, 1};
   std::vector<xgboost::bst_float> out_preds = {1, 1.10, 1.64, 2.45, 2.71};
   obj->PredTransform(&preds);
-  for (int i = 0; i < preds.size(); ++i) {
+  for (int i = 0; i < static_cast<int>(preds.size()); ++i) {
     EXPECT_NEAR(preds[i], out_preds[i], 0.01);
   }
 }
@@ -168,7 +168,7 @@ TEST(Objective, TweedieRegressionBasic) {
   std::vector<xgboost::bst_float> preds = {0, 0.1, 0.5, 0.9, 1};
   std::vector<xgboost::bst_float> out_preds = {1, 1.10, 1.64, 2.45, 2.71};
   obj->PredTransform(&preds);
-  for (int i = 0; i < preds.size(); ++i) {
+  for (int i = 0; i < static_cast<int>(preds.size()); ++i) {
     EXPECT_NEAR(preds[i], out_preds[i], 0.01);
   }
 }

tests/cpp/xgboost_test.mk

@@ -1,9 +1,21 @@
 UTEST_ROOT=tests/cpp
 UTEST_OBJ_ROOT=build_$(UTEST_ROOT)
 UNITTEST=$(UTEST_ROOT)/xgboost_test
+
 UNITTEST_SRC=$(wildcard $(UTEST_ROOT)/*.cc $(UTEST_ROOT)/*/*.cc)
 UNITTEST_OBJ=$(patsubst $(UTEST_ROOT)%.cc, $(UTEST_OBJ_ROOT)%.o, $(UNITTEST_SRC))
 
+# for if and when we add cuda source files into xgboost core
+UNITTEST_CU_SRC=$(wildcard $(UTEST_ROOT)/*.cu $(UTEST_ROOT)/*/*.cu)
+UNITTEST_OBJ += $(patsubst $(UTEST_ROOT)%.cu, $(UTEST_OBJ_ROOT)%.o, $(UNITTEST_CU_SRC))
+
+# tests from grow_gpu plugin (only if CUDA path is enabled!)
+ifeq ($(PLUGIN_UPDATER_GPU),ON)
+  GPU_PLUGIN_FOLDER = plugin/updater_gpu
+  UNITTEST_CU_PLUGIN_SRC = $(wildcard $(GPU_PLUGIN_FOLDER)/test/cpp/*.cu)
+  UNITTEST_OBJ += $(patsubst %.cu, $(UTEST_OBJ_ROOT)/%.o, $(UNITTEST_CU_PLUGIN_SRC))
+endif
+
 GTEST_LIB=$(GTEST_PATH)/lib/
 GTEST_INC=$(GTEST_PATH)/include/
 
@@ -13,6 +25,19 @@ UNITTEST_DEPS=lib/libxgboost.a $(DMLC_CORE)/libdmlc.a $(RABIT)/lib/$(LIB_RABIT)
 
 COVER_OBJ=$(patsubst %.o, %.gcda, $(ALL_OBJ)) $(patsubst %.o, %.gcda, $(UNITTEST_OBJ))
 
+# the order of the below targets matter!
+$(UTEST_OBJ_ROOT)/$(GPU_PLUGIN_FOLDER)/test/cpp/%.o: $(GPU_PLUGIN_FOLDER)/test/cpp/%.cu
+	@mkdir -p $(@D)
+	$(NVCC) $(NVCC_FLAGS) -I$(GTEST_INC) -o $@ -c $<
+
+$(UTEST_OBJ_ROOT)/%.o: $(UTEST_ROOT)/%.cu
+	@mkdir -p $(@D)
+	$(NVCC) $(NVCC_FLAGS) -I$(GTEST_INC) -o $@ -c $<
+
+$(UTEST_OBJ_ROOT)/$(GTEST_PATH)/%.o: $(GTEST_PATH)/%.cc
+	@mkdir -p $(@D)
+	$(CXX) $(UNITTEST_CFLAGS) -I$(GTEST_INC) -I$(GTEST_PATH) -o $@ -c $<
+
 $(UTEST_OBJ_ROOT)/%.o: $(UTEST_ROOT)/%.cc
 	@mkdir -p $(@D)
 	$(CXX) $(UNITTEST_CFLAGS) -I$(GTEST_INC) -o $@ -c $<