expression: implement vectorized evaluation for builtinCastTimeAsTime…

…Sig (#13209)

expression/builtin_cast_vec.go

@@ -1151,11 +1151,42 @@ func (b *builtinCastTimeAsIntSig) vecEvalInt(input *chunk.Chunk, result *chunk.C
 }
 
 func (b *builtinCastTimeAsTimeSig) vectorized() bool {
-	return false
+	return true
 }
 
 func (b *builtinCastTimeAsTimeSig) vecEvalTime(input *chunk.Chunk, result *chunk.Column) error {
-	return errors.Errorf("not implemented")
+	n := input.NumRows()
+	if err := b.args[0].VecEvalTime(b.ctx, input, result); err != nil {
+		return err
+	}
+
+	times := result.Times()
+	stmt := b.ctx.GetSessionVars().StmtCtx
+	fsp := int8(b.tp.Decimal)
+	for i := 0; i < n; i++ {
+		if result.IsNull(i) {
+			continue
+		}
+		res, err := times[i].Convert(stmt, b.tp.Tp)
+		if err != nil {
+			if err = handleInvalidTimeError(b.ctx, err); err != nil {
+				return err
+			}
+			result.SetNull(i, true)
+			continue
+		}
+		tm, err := res.RoundFrac(stmt, fsp)
+		if err != nil {
+			return err
+		}
+		times[i] = tm
+		if b.tp.Tp == mysql.TypeDate {
+			// Truncate hh:mm:ss part if the type is Date.
+			times[i].Time = types.FromDate(tm.Time.Year(), tm.Time.Month(), tm.Time.Day(), 0, 0, 0, 0)
+			times[i].Type = b.tp.Tp
+		}
+	}
+	return nil
 }
 
 func (b *builtinCastTimeAsStringSig) vectorized() bool {

expression/builtin_cast_vec_test.go

@@ -73,6 +73,8 @@ var vecBuiltinCastCases = map[string][]vecExprBenchCase{
 				&dataStrGener{},
 			}},
 		{retEvalType: types.ETDatetime, childrenTypes: []types.EvalType{types.ETDuration}},
+		{retEvalType: types.ETDatetime, childrenTypes: []types.EvalType{types.ETDatetime}},
+		{retEvalType: types.ETDatetime, childrenTypes: []types.EvalType{types.ETTimestamp}},
 	},
 }