[mlir][Math] Add constant folder for SinOp.

[jacquesguan]

Summary

This patch adds constant folder for SinOp by using sin/sinf of libm.

[jacquesguan]

fix typo.

mlir/include/mlir/Dialect/Math/IR/MathOps.td

let description = [{
 
     Example:
 
     ```mlir
     // Scalar sine value.
     %a = math.sin %b : f64
     ```
   }];
+  let hasFolder = 1;
 }
 
 //===----------------------------------------------------------------------===//
 // CountLeadingZerosOp
 //===----------------------------------------------------------------------===//
 
 def Math_CountLeadingZerosOp : Math_IntegerUnaryOp<"ctlz"> {
   let summary = "counts the leading zeros an integer value";

mlir/lib/Dialect/Math/IR/MathOps.cpp

return constFoldUnaryOpConditional<FloatAttr>(
           return APFloat(cosf(a.convertToFloat()));
         default:
           return {};
         }
       });
 }
 
 //===----------------------------------------------------------------------===//
+// SinOp folder
+//===----------------------------------------------------------------------===//
+
+OpFoldResult math::SinOp::fold(ArrayRef<Attribute> operands) {
+  return constFoldUnaryOpConditional<FloatAttr>(
+      operands, [](const APFloat &a) -> Optional<APFloat> {
+        switch (a.getSizeInBits(a.getSemantics())) {
+        case 64:
+          return APFloat(sin(a.convertToDouble()));
+        case 32:
+          return APFloat(sinf(a.convertToFloat()));
+        default:
+          return {};
+        }
+      });
+}
+
+//===----------------------------------------------------------------------===//
 // CountLeadingZerosOp folder
 //===----------------------------------------------------------------------===//
 
 OpFoldResult math::CountLeadingZerosOp::fold(ArrayRef<Attribute> operands) {
   return constFoldUnaryOp<IntegerAttr>(operands, [](const APInt &a) {
     return APInt(a.getBitWidth(), a.countLeadingZeros());
   });
 }

mlir/test/Dialect/Math/canonicalize.mlir

 // CHECK-LABEL: @trunc_fold_vec
 // CHECK-NEXT: %[[cst:.+]] = arith.constant dense<[0.000000e+00, -0.000000e+00, 1.000000e+00, -1.000000e+00]> : vector<4xf32>
 // CHECK-NEXT:   return %[[cst]]
 func.func @trunc_fold_vec() -> (vector<4xf32>) {
   %v = arith.constant dense<[0.5, -0.5, 1.5, -1.5]> : vector<4xf32>
   %0 = math.trunc %v : vector<4xf32>
   return %0 : vector<4xf32>
 }
+
+// CHECK-LABEL: @sin_fold
+// CHECK-NEXT: %[[cst:.+]] = arith.constant 0.84{{[0-9]+}} : f32
+// CHECK-NEXT:   return %[[cst]]
+func.func @sin_fold() -> f32 {
+  %c = arith.constant 1.0 : f32
+  %r = math.sin %c : f32
+  return %r : f32
+}
+
+// CHECK-LABEL: @sin_fold_vec
+// CHECK-NEXT: %[[cst:.+]] = arith.constant dense<[0.000000e+00, 0.84{{[0-9]+}}, 0.000000e+00, 0.84{{[0-9]+}}]> : vector<4xf32>
+// CHECK-NEXT:   return %[[cst]]
+func.func @sin_fold_vec() -> (vector<4xf32>) {
+  %v1 = arith.constant dense<[0.0, 1.0, 0.0, 1.0]> : vector<4xf32>
+  %0 = math.sin %v1 : vector<4xf32>
+  return %0 : vector<4xf32>
+}