Convert exp(x-1) into expm1(x).

PiperOrigin-RevId: 202598404

1 files changed, 42 insertions, 0 deletions

diff --git a/tensorflow/core/grappler/optimizers/arithmetic_optimizer_test.cc b/tensorflow/core/grappler/optimizers/arithmetic_optimizer_test.cc
index d0e6b04679..3f6c04a5b5 100644
--- a/tensorflow/core/grappler/optimizers/arithmetic_optimizer_test.cc
+++ b/tensorflow/core/grappler/optimizers/arithmetic_optimizer_test.cc
@@ -274,6 +274,11 @@ class ArithmeticOptimizerTest : public GrapplerTest {
     DisableAllStages(optimizer);
     optimizer->options_.optimize_max_or_min_of_monotonic = true;
   }
+
+  void EnableOnlyExpm1(ArithmeticOptimizer* optimizer) {
+    DisableAllStages(optimizer);
+    optimizer->options_.convert_expm1 = true;
+  }
 };
 
 TEST_F(ArithmeticOptimizerTest, NoOp) {
@@ -2533,6 +2538,43 @@ TEST_F(ArithmeticOptimizerTest, Log1p) {
   CompareGraphs(want, got);
 }
 
+TEST_F(ArithmeticOptimizerTest, Expm1) {
+  tensorflow::Scope s = tensorflow::Scope::NewRootScope();
+
+  auto x1 = ops::Const(s.WithOpName("x1"), {2.0f, 2.0f}, {1, 2});
+  auto x2 = ops::Const(s.WithOpName("x2"), {1.0f, 1.0f}, {1, 2});
+  auto x3 = ops::Const(s.WithOpName("x3"), {3.0f, 3.0f}, {1, 2});
+  auto s12 = ops::Sub(s.WithOpName("s12").WithControlDependencies(x3), x1, x2);
+  auto s23 = ops::Sub(s.WithOpName("s23"), x2, x3);
+  Output out1 = ops::Exp(s.WithOpName("out1"), s12);
+  Output out2 = ops::Exp(s.WithOpName("out2"), s23);
+
+  GrapplerItem item;
+  item.fetch = {"out1", "out2"};
+  TF_CHECK_OK(s.ToGraphDef(&item.graph));
+  auto tensors_expected = EvaluateNodes(item.graph, item.fetch);
+  EXPECT_EQ(2, tensors_expected.size());
+
+  GraphDef got;
+  ArithmeticOptimizer optimizer;
+  EnableOnlyExpm1(&optimizer);
+  OptimizeAndPrune(&optimizer, &item, &got);
+  auto tensors = EvaluateNodes(got, item.fetch);
+  EXPECT_EQ(2, tensors.size());
+
+  GraphDef want;
+  AddNode("x1", "Const", {}, {}, &want);
+  AddNode("x2", "Const", {}, {}, &want);
+  AddNode("x3", "Const", {}, {}, &want);
+  AddNode("s23", "Sub", {"x2", "x3"}, {}, &want);
+  AddNode("out1", "Expm1",
+          {"x1", AsControlDependency("x2"), AsControlDependency("x3")}, {},
+          &want);
+  AddNode("out2", "Exp", {"s23"}, {}, &want);
+
+  CompareGraphs(want, got);
+}
+
 TEST_F(ArithmeticOptimizerTest, MinimizeBroadcasts_SimpleSwap) {
   tensorflow::Scope s = tensorflow::Scope::NewRootScope();