/// <summary>
/// Tests whether we should prefer a switch statement over an if statement.
/// </summary>
static bool UseCSharpSwitch(SwitchAnalysis analysis, out KeyValuePair <LongSet, ILInstruction> defaultSection)
{
if (!analysis.InnerBlocks.Any())
{
defaultSection = default(KeyValuePair <LongSet, ILInstruction>);
return(false);
}
defaultSection = analysis.Sections.FirstOrDefault(s => s.Key.Count() > MaxValuesPerSection);
if (defaultSection.Key.IsEmpty)
{
return(false);
}
ulong valuePerSectionLimit = MaxValuesPerSection;
if (!analysis.ContainsILSwitch)
{
// If there's no IL switch involved, limit the number of keys per section
// much more drastically to avoid generating switches where an if condition
// would be shorter.
valuePerSectionLimit = Math.Min(
valuePerSectionLimit,
(ulong)analysis.InnerBlocks.Count);
}
var defaultSectionKey = defaultSection.Key;
if (analysis.Sections.Any(s => !s.Key.SetEquals(defaultSectionKey) &&
s.Key.Count() > valuePerSectionLimit))
{
return(false);
}
return(analysis.InnerBlocks.Any());
}
/// <summary>
/// Tests whether we should prefer a switch statement over an if statement.
/// </summary>
static bool UseCSharpSwitch(SwitchAnalysis analysis, out KeyValuePair <LongSet, ILInstruction> defaultSection)
{
if (!analysis.InnerBlocks.Any())
{
defaultSection = default(KeyValuePair <LongSet, ILInstruction>);
return(false);
}
defaultSection = analysis.Sections.FirstOrDefault(s => s.Key.Count() > MaxValuesPerSection);
if (defaultSection.Value == null)
{
// no default section found?
// This should never happen, as we'd need 2^64/MaxValuesPerSection sections to hit this case...
return(false);
}
ulong valuePerSectionLimit = MaxValuesPerSection;
if (!analysis.ContainsILSwitch)
{
// If there's no IL switch involved, limit the number of keys per section
// much more drastically to avoid generating switches where an if condition
// would be shorter.
valuePerSectionLimit = Math.Min(
valuePerSectionLimit,
(ulong)analysis.InnerBlocks.Count);
}
var defaultSectionKey = defaultSection.Key;
if (analysis.Sections.Any(s => !s.Key.SetEquals(defaultSectionKey) &&
s.Key.Count() > valuePerSectionLimit))
{
// Only the default section is allowed to have tons of keys.
// C# doesn't support "case 1 to 100000000", and we don't want to generate
// gigabytes of case labels.
return(false);
}
return(true);
}