From c3e19549184e16dd04a560fc18edb098f5fc5883 Mon Sep 17 00:00:00 2001
From: mapingshuo <mps2012@yeah.net>
Date: Fri, 27 Dec 2019 16:23:43 +0800
Subject: [PATCH] make reverse op support negative axis (#21925)

* make reverse op support negative axis
---
 paddle/fluid/operators/reverse_op.cc          |  8 ++++++-
 paddle/fluid/operators/reverse_op.h           |  6 ++++-
 .../fluid/tests/unittests/test_reverse_op.py  | 24 +++++++++++++++++++
 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/paddle/fluid/operators/reverse_op.cc b/paddle/fluid/operators/reverse_op.cc
index 1c3b3d3c2f..f50450bc2a 100644
--- a/paddle/fluid/operators/reverse_op.cc
+++ b/paddle/fluid/operators/reverse_op.cc
@@ -31,7 +31,13 @@ class ReverseOp : public framework::OperatorWithKernel {
     PADDLE_ENFORCE(!axis.empty(), "'axis' can not be empty.");
     for (int a : axis) {
       PADDLE_ENFORCE_LT(a, x_dims.size(),
-                        "The axis must be less than input tensor's rank.");
+                        paddle::platform::errors::OutOfRange(
+                            "The axis must be less than input tensor's rank."));
+      PADDLE_ENFORCE_GE(
+          a, -x_dims.size(),
+          paddle::platform::errors::OutOfRange(
+              "The axis must be greater than the negative number of "
+              "input tensor's rank."));
     }
     ctx->SetOutputDim("Out", x_dims);
   }
diff --git a/paddle/fluid/operators/reverse_op.h b/paddle/fluid/operators/reverse_op.h
index 9063cd59bb..c5535a6dc2 100644
--- a/paddle/fluid/operators/reverse_op.h
+++ b/paddle/fluid/operators/reverse_op.h
@@ -28,7 +28,11 @@ struct ReverseFunctor {
       reverse_axis[i] = false;
     }
     for (int a : axis) {
-      reverse_axis[a] = true;
+      if (a >= 0) {
+        reverse_axis[a] = true;
+      } else {
+        reverse_axis[Rank + a] = true;
+      }
     }
 
     auto in_eigen = framework::EigenTensor<T, Rank>::From(in);
diff --git a/python/paddle/fluid/tests/unittests/test_reverse_op.py b/python/paddle/fluid/tests/unittests/test_reverse_op.py
index 09252f47d2..80f0562132 100644
--- a/python/paddle/fluid/tests/unittests/test_reverse_op.py
+++ b/python/paddle/fluid/tests/unittests/test_reverse_op.py
@@ -47,23 +47,47 @@ class TestCase0(TestReverseOp):
         self.axis = [1]
 
 
+class TestCase0(TestReverseOp):
+    def initTestCase(self):
+        self.x = np.random.random((3, 40)).astype('float64')
+        self.axis = [-1]
+
+
 class TestCase1(TestReverseOp):
     def initTestCase(self):
         self.x = np.random.random((3, 40)).astype('float64')
         self.axis = [0, 1]
 
 
+class TestCase0(TestReverseOp):
+    def initTestCase(self):
+        self.x = np.random.random((3, 40)).astype('float64')
+        self.axis = [0, -1]
+
+
 class TestCase2(TestReverseOp):
     def initTestCase(self):
         self.x = np.random.random((3, 4, 10)).astype('float64')
         self.axis = [0, 2]
 
 
+class TestCase2(TestReverseOp):
+    def initTestCase(self):
+        self.x = np.random.random((3, 4, 10)).astype('float64')
+        self.axis = [0, -2]
+
+
 class TestCase3(TestReverseOp):
     def initTestCase(self):
         self.x = np.random.random((3, 4, 10)).astype('float64')
         self.axis = [1, 2]
 
 
+class TestCase3(TestReverseOp):
+    def initTestCase(self):
+        self.x = np.random.random((3, 4, 10)).astype('float64')
+        self.axis = [-1, -2]
+
+
 if __name__ == '__main__':
     unittest.main()
-- 
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