[MLIR][KernelGen] Lower `tf.Sinh` to MLHLO

PiperOrigin-RevId: 332425724

include/mlir-hlo/Dialect/mhlo/IR/chlo_ops.td

@@ -366,6 +366,20 @@ def HLOClient_AcosOp : HLOClient_UnaryElementwiseOp<"acos", [],
   }];
 }
 
+def HLOClient_SinhOp : HLOClient_UnaryElementwiseOp<"sinh", [],
+    HLO_FpOrComplexTensor> {
+  let summary = "Sinh operation";
+
+  let description = [{
+    Returns `Sinh(operand)` element-wise.
+
+    $$
+    \sinh(x) = (e^x - e^-x) / 2                     if |x| < 1
+             = e^(x + log(1/2)) - e^(-x + log(1/2)) otherwise.
+    $$
+  }];
+}
+
 def HLOClient_TanOp : HLOClient_UnaryElementwiseOp<"tan", [],
     HLO_FpOrComplexTensor> {
   let summary = "Tan operation";

lib/Dialect/mhlo/transforms/chlo_legalize_to_hlo_patterns.td

@@ -49,6 +49,45 @@ def : Pat<(HLOClient_AcosOp $input),
     ),
     (HLO_ConstantLike<"M_PI"> $input))>;
 
+// Express `sinh` as
+//   sinh(x) = (e^x - e^-x) / 2                     if |x| < 1
+//           = e^(x + log(1/2)) - e^(-x + log(1/2)) otherwise.
+def : Pat<(HLOClient_SinhOp $input),
+  (HLO_SelectOp
+    (HLO_CompareOp
+      (HLO_AbsOp $input),
+      (HLO_ConstantLike<"1"> $input),
+      HLO_COMPARISON_DIRECTION_LT
+    ),
+    (HLO_DivOp
+      (HLO_SubOp
+        (HLO_ExpOp $input),
+        (HLO_ExpOp
+          (HLO_NegOp $input)
+        )
+      ),
+      (HLO_ConstantLike<"2"> $input)
+    ),
+    (HLO_SubOp
+      (HLO_ExpOp
+        (HLO_AddOp
+          $input,
+          (HLO_LogOp
+            (HLO_ConstantLike<"0.5"> $input)
+          )
+        )
+      ),
+      (HLO_ExpOp
+        (HLO_SubOp
+          (HLO_LogOp
+            (HLO_ConstantLike<"0.5"> $input)
+          ),
+          $input
+        )
+      )
+    )
+  )>;
+
 // Express tan in MHLO dialect as
 //   tan(x) = sin(x) / cos(x).
 def : Pat<(HLOClient_TanOp $input),

lib/Dialect/mhlo/transforms/transform_unranked_hlo.cc

@@ -47,7 +47,8 @@ namespace {
               sep fn(ShiftRightLogicalOp) sep fn(SubOp)
 
 // TODO(herhut): Generate these out of op definitions.
-#define MAP_CHLO_OPERATION_CWISE_UNARY(fn, sep) fn(TanOp) sep fn(AcosOp)
+#define MAP_CHLO_OPERATION_CWISE_UNARY(fn, sep) \
+  fn(TanOp) sep fn(AcosOp) sep fn(SinhOp)
 
 template <typename OpTy>
 inline void AddLegalOpOnRankedTensor(ConversionTarget *target) {