Throw when attempting to move IndexPQ to GPU (#3328)

Summary: Pull Request resolved: #3328

Reviewed By: junjieqi

Differential Revision: D55476917

fbshipit-source-id: e7f64adefa07650fda32ad2300a1b933cedc9c79

faiss/gpu/GpuCloner.cpp

@@ -224,6 +224,8 @@ faiss::Index* index_cpu_to_gpu(
         int device,
         const faiss::Index* index,
         const GpuClonerOptions* options) {
+    auto index_pq = dynamic_cast<const faiss::IndexPQ*>(index);
+    FAISS_THROW_IF_MSG(index_pq, "This index type is not implemented on GPU.");
     GpuClonerOptions defaults;
     ToGpuCloner cl(provider, device, options ? *options : defaults);
     return cl.clone_Index(index);

faiss/gpu/test/test_index_cpu_to_gpu.py

@@ -0,0 +1,29 @@
+import numpy as np
+import unittest
+import faiss
+
+
+class TestMoveToGpu(unittest.TestCase):
+    def test_index_cpu_to_gpu(self):
+        dimension = 128
+        n = 2500
+        db_vectors = np.random.random((n, dimension)).astype('float32')
+        code_size = 16
+        res = faiss.StandardGpuResources()
+        index_pq = faiss.IndexPQ(dimension, code_size, 6)
+        index_pq.train(db_vectors)
+        index_pq.add(db_vectors)
+        self.assertRaisesRegex(Exception, ".*not implemented.*",
+                               faiss.index_cpu_to_gpu, res, 0, index_pq)
+
+    def test_index_cpu_to_gpu_does_not_throw_with_index_flat(self):
+        dimension = 128
+        n = 100
+        db_vectors = np.random.random((n, dimension)).astype('float32')
+        res = faiss.StandardGpuResources()
+        index_flat = faiss.IndexFlatL2(dimension)
+        index_flat.add(db_vectors)
+        try:
+            faiss.index_cpu_to_gpu(res, 0, index_flat)
+        except Exception:
+            self.fail("index_cpu_to_gpu() threw an unexpected exception.")

faiss/impl/FaissAssert.h

@@ -94,6 +94,13 @@
         }                                              \
     } while (false)
 
+#define FAISS_THROW_IF_MSG(X, MSG)                           \
+    do {                                                     \
+        if (X) {                                             \
+            FAISS_THROW_FMT("Error: '%s' failed: " MSG, #X); \
+        }                                                    \
+    } while (false)
+
 #define FAISS_THROW_IF_NOT_MSG(X, MSG)                       \
     do {                                                     \
         if (!(X)) {                                          \