Small FormattedLogValues Parameter Lookup Optimization

[snakefoot]

Maybe this code:

runtime/src/libraries/Microsoft.Extensions.Logging.Abstractions/src/FormattedLogValues.cs

Lines 63 to 73 in 96acc3c

	public KeyValuePair<string, object?> this[int index]
	{
	get
	{
	if (index < 0 || index >= Count)
	{
	throw new IndexOutOfRangeException();
	}
	if (index == Count - 1)
	{

Can be optimized to single Count-Lookup like this:

 public KeyValuePair<string, object?> this[int index] 
 { 
     get 
     {
         var parameterCount = Count;
         if (index < 0 || index >= parameterCount) 
         { 
             throw new IndexOutOfRangeException(); 
         } 
  
         if (index == parameterCount - 1) 

Since Count is a "complex" method:

runtime/src/libraries/Microsoft.Extensions.Logging.Abstractions/src/FormattedLogValues.cs

Lines 81 to 90 in 96acc3c

	public int Count
	{
	get
	{
	if (_formatter == null)
	{
	return 1;
	}
	return _formatter.ValueNames.Count + 1;

[snakefoot]

Maybe same can be done for GetEnumerator:

runtime/src/libraries/Microsoft.Extensions.Logging.Abstractions/src/FormattedLogValues.cs

Lines 94 to 98 in 96acc3c

	public IEnumerator<KeyValuePair<string, object?>> GetEnumerator()
	{
	for (int i = 0; i < Count; ++i)
	{
	yield return this[i];

Like this:

 public IEnumerator<KeyValuePair<string, object?>> GetEnumerator() 
 {
     var parameterCount = Count;
     for (int i = 0; i < parameterCount; ++i) 
     { 
         yield return this[i]; 

[tarekgh]

@snakefoot
Could you please try to measure the suggested change and share the benchmark numbers?