[mlir][math] Lower atan to libm

mlir/lib/Conversion/MathToLibm/MathToLibm.cpp

ScalarOpToLibmCall<Op>::matchAndRewrite(Op op,
   return success();
 }
 
 void mlir::populateMathToLibmConversionPatterns(RewritePatternSet &patterns,
                                                 PatternBenefit benefit) {
   patterns.add<VecOpToScalarOp<math::Atan2Op>, VecOpToScalarOp<math::ExpM1Op>,
                VecOpToScalarOp<math::TanhOp>, VecOpToScalarOp<math::CosOp>,
                VecOpToScalarOp<math::SinOp>, VecOpToScalarOp<math::ErfOp>,
-               VecOpToScalarOp<math::RoundOp>>(patterns.getContext(), benefit);
+               VecOpToScalarOp<math::RoundOp>, VecOpToScalarOp<math::AtanOp>>(
+      patterns.getContext(), benefit);
   patterns.add<PromoteOpToF32<math::Atan2Op>, PromoteOpToF32<math::ExpM1Op>,
                PromoteOpToF32<math::TanhOp>, PromoteOpToF32<math::CosOp>,
                PromoteOpToF32<math::SinOp>, PromoteOpToF32<math::ErfOp>,
-               PromoteOpToF32<math::RoundOp>>(patterns.getContext(), benefit);
+               PromoteOpToF32<math::RoundOp>, PromoteOpToF32<math::AtanOp>>(
+      patterns.getContext(), benefit);
+  patterns.add<ScalarOpToLibmCall<math::AtanOp>>(patterns.getContext(), "atanf",
+                                                 "atan", benefit);
   patterns.add<ScalarOpToLibmCall<math::Atan2Op>>(patterns.getContext(),
                                                   "atan2f", "atan2", benefit);
   patterns.add<ScalarOpToLibmCall<math::ErfOp>>(patterns.getContext(), "erff",
                                                 "erf", benefit);
   patterns.add<ScalarOpToLibmCall<math::ExpM1Op>>(patterns.getContext(),
                                                   "expm1f", "expm1", benefit);
   patterns.add<ScalarOpToLibmCall<math::TanhOp>>(patterns.getContext(), "tanhf",
                                                  "tanh", benefit);

mlir/test/Conversion/MathToLibm/convert-to-libm.mlir

 // RUN: mlir-opt %s -convert-math-to-libm -canonicalize | FileCheck %s
 
+// CHECK-DAG: @atan(f64) -> f64
+// CHECK-DAG: @atanf(f32) -> f32
 // CHECK-DAG: @erf(f64) -> f64
 // CHECK-DAG: @erff(f32) -> f32
 // CHECK-DAG: @expm1(f64) -> f64
 // CHECK-DAG: @expm1f(f32) -> f32
 // CHECK-DAG: @atan2(f64, f64) -> f64
 // CHECK-DAG: @atan2f(f32, f32) -> f32
 // CHECK-DAG: @tanh(f64) -> f64
 // CHECK-DAG: @tanhf(f32) -> f32
 // CHECK-DAG: @round(f64) -> f64
 // CHECK-DAG: @roundf(f32) -> f32
 // CHECK-DAG: @cos(f64) -> f64
 // CHECK-DAG: @cosf(f32) -> f32
 // CHECK-DAG: @sin(f64) -> f64
 // CHECK-DAG: @sinf(f32) -> f32
 
+// CHECK-LABEL: func @atan_caller
+// CHECK-SAME: %[[FLOAT:.*]]: f32
+// CHECK-SAME: %[[DOUBLE:.*]]: f64
+// CHECK-SAME: %[[HALF:.*]]: f16
+// CHECK-SAME: %[[BFLOAT:.*]]: bf16
+func.func @atan_caller(%float: f32, %double: f64, %half: f16, %bfloat: bf16) -> (f32, f64, f16, bf16)  {
+  // CHECK: %[[FLOAT_RESULT:.*]] = call @atanf(%[[FLOAT]]) : (f32) -> f32
+  %float_result = math.atan %float : f32
+  // CHECK: %[[DOUBLE_RESULT:.*]] = call @atan(%[[DOUBLE]]) : (f64) -> f64
+  %double_result = math.atan %double : f64
+  // CHECK: %[[HALF_PROMOTED:.*]] = arith.extf %[[HALF]] : f16 to f32
+  // CHECK: %[[HALF_CALL:.*]] = call @atanf(%[[HALF_PROMOTED]]) : (f32) -> f32
+  // CHECK: %[[HALF_RESULT:.*]] = arith.truncf %[[HALF_CALL]] : f32 to f16
+  %half_result = math.atan %half : f16
+  // CHECK: %[[BFLOAT_PROMOTED:.*]] = arith.extf %[[BFLOAT]] : bf16 to f32
+  // CHECK: %[[BFLOAT_CALL:.*]] = call @atanf(%[[BFLOAT_PROMOTED]]) : (f32) -> f32
+  // CHECK: %[[BFLOAT_RESULT:.*]] = arith.truncf %[[BFLOAT_CALL]] : f32 to bf16
+  %bfloat_result = math.atan %bfloat : bf16
+  // CHECK: return %[[FLOAT_RESULT]], %[[DOUBLE_RESULT]], %[[HALF_RESULT]], %[[BFLOAT_RESULT]]
+  return %float_result, %double_result, %half_result, %bfloat_result : f32, f64, f16, bf16
+}
+
+// CHECK-LABEL:   func @atan_vec_caller(
+// CHECK-SAME:                           %[[VAL_0:.*]]: vector<2xf32>,
+// CHECK-SAME:                           %[[VAL_1:.*]]: vector<2xf64>) -> (vector<2xf32>, vector<2xf64>) {
+// CHECK-DAG:       %[[CVF:.*]] = arith.constant dense<0.000000e+00> : vector<2xf32>
+// CHECK-DAG:       %[[CVD:.*]] = arith.constant dense<0.000000e+00> : vector<2xf64>
+// CHECK:           %[[IN0_F32:.*]] = vector.extract %[[VAL_0]][0] : vector<2xf32>
+// CHECK:           %[[OUT0_F32:.*]] = call @atanf(%[[IN0_F32]]) : (f32) -> f32
+// CHECK:           %[[VAL_8:.*]] = vector.insert %[[OUT0_F32]], %[[CVF]] [0] : f32 into vector<2xf32>
+// CHECK:           %[[IN1_F32:.*]] = vector.extract %[[VAL_0]][1] : vector<2xf32>
+// CHECK:           %[[OUT1_F32:.*]] = call @atanf(%[[IN1_F32]]) : (f32) -> f32
+// CHECK:           %[[VAL_11:.*]] = vector.insert %[[OUT1_F32]], %[[VAL_8]] [1] : f32 into vector<2xf32>
+// CHECK:           %[[IN0_F64:.*]] = vector.extract %[[VAL_1]][0] : vector<2xf64>
+// CHECK:           %[[OUT0_F64:.*]] = call @atan(%[[IN0_F64]]) : (f64) -> f64
+// CHECK:           %[[VAL_14:.*]] = vector.insert %[[OUT0_F64]], %[[CVD]] [0] : f64 into vector<2xf64>
+// CHECK:           %[[IN1_F64:.*]] = vector.extract %[[VAL_1]][1] : vector<2xf64>
+// CHECK:           %[[OUT1_F64:.*]] = call @atan(%[[IN1_F64]]) : (f64) -> f64
+// CHECK:           %[[VAL_17:.*]] = vector.insert %[[OUT1_F64]], %[[VAL_14]] [1] : f64 into vector<2xf64>
+// CHECK:           return %[[VAL_11]], %[[VAL_17]] : vector<2xf32>, vector<2xf64>
+// CHECK:         }
+func.func @atan_vec_caller(%float: vector<2xf32>, %double: vector<2xf64>) -> (vector<2xf32>, vector<2xf64>) {
+  %float_result = math.atan %float : vector<2xf32>
+  %double_result = math.atan %double : vector<2xf64>
+  return %float_result, %double_result : vector<2xf32>, vector<2xf64>
+}
+
 // CHECK-LABEL: func @tanh_caller
 // CHECK-SAME: %[[FLOAT:.*]]: f32
 // CHECK-SAME: %[[DOUBLE:.*]]: f64
 func.func @tanh_caller(%float: f32, %double: f64) -> (f32, f64)  {
   // CHECK-DAG: %[[FLOAT_RESULT:.*]] = call @tanhf(%[[FLOAT]]) : (f32) -> f32
   %float_result = math.tanh %float : f32
   // CHECK-DAG: %[[DOUBLE_RESULT:.*]] = call @tanh(%[[DOUBLE]]) : (f64) -> f64
   %double_result = math.tanh %double : f64