Add complex backward support for torch.exp (#47194)

Summary: Pull Request resolved: #47194

Test Plan: Imported from OSS

Reviewed By: izdeby

Differential Revision: D24683201

Pulled By: anjali411

fbshipit-source-id: c447dec51cbfe7c09d6943fbaafa94f48130d582

test/test_autograd.py

@@ -4938,7 +4938,8 @@ def run_functional_checks(test_case, test_name, name, apply_fn, run_grad_checks,
                 'chunk', 'split', 'split_with_sizes', 'repeat', 'expand', 'zero_',
                 'eq_', 'ne_', 'add', '__radd__', 'sum', 'conj', 'sin', 'cos', 'mul', 'sinh',
                 'cosh', '__rmul__', 'sgn', 'abs', 'dot', 'vdot', 'tensor_split', 'matmul',
-                'bmm', 'mv', 'ger', 'diagonal', 'atan', 'angle', 'tanh', 'fill_', 'sub'] + separate_complex_tests
+                'bmm', 'mv', 'ger', 'diagonal', 'atan', 'angle', 'tanh', 'fill_', 'sub',
+                'exp'] + separate_complex_tests
 
 # this list corresponds to cases that are not currently implemented
 skip_cuda_list = ['bmm_complex', 'matmul_4d_4d_complex']

tools/autograd/derivatives.yaml

@@ -434,7 +434,7 @@
   self: 0.5 * sqrt(M_PI) * exp(self.erfinv().pow(2)) * grad
 
 - name: exp(Tensor self) -> Tensor
-  self: grad * result
+  self: grad * result.conj()
 
 - name: exp2(Tensor self) -> Tensor
   self: grad * result * M_LN2

tools/autograd/gen_variable_type.py

@@ -166,7 +166,8 @@
     'unbind', 'split', 'split_with_sizes', 'unsafe_split', 'split_with_sizes_backward',
     'dot', 'vdot', 'cholesky', 'triangular_solve', 'mm', '_unsafe_view', 'mv', 'ger',
     'bmm', 'diagonal', 'cholesky', 'atan', 'log', 'log10', 'log1p', 'log2', 'reciprocal',
-    'tan', 'pow', 'rsqrt', 'tanh', 'tanh_backward', 'asinh', 'acosh', 'take', 'fill_'
+    'tan', 'pow', 'rsqrt', 'tanh', 'tanh_backward', 'asinh', 'acosh', 'take', 'fill_',
+    'exp'
 }
 
 # Some operators invalidate the grad_accumulator. Let's reset it.