/// <summary>
/// Handles NullCoalescingInstruction case 1: reference types.
///
/// stloc s(valueInst)
/// if (comp(ldloc s == ldnull)) {
/// stloc s(fallbackInst)
/// }
/// =>
/// stloc s(if.notnull(valueInst, fallbackInst))
/// </summary>
bool TransformRefTypes(Block block, int pos, StatementTransformContext context)
{
if (!(block.Instructions[pos] is StLoc stloc))
{
return(false);
}
if (stloc.Variable.Kind != VariableKind.StackSlot)
{
return(false);
}
if (!block.Instructions[pos + 1].MatchIfInstruction(out var condition, out var trueInst))
{
return(false);
}
trueInst = Block.Unwrap(trueInst);
if (condition.MatchCompEquals(out var left, out var right) && left.MatchLdLoc(stloc.Variable) && right.MatchLdNull() &&
trueInst.MatchStLoc(stloc.Variable, out var fallbackValue)
)
{
context.Step("NullCoalescingTransform (reference types)", stloc);
stloc.Value = new NullCoalescingInstruction(NullCoalescingKind.Ref, stloc.Value, fallbackValue);
block.Instructions.RemoveAt(pos + 1); // remove if instruction
ILInlining.InlineOneIfPossible(block, pos, false, context);
return(true);
}
return(false);
}
public void Run(Block block, BlockTransformContext context)
{
this.context = context;
if (!context.Settings.AnonymousMethods)
{
return;
}
for (int i = block.Instructions.Count - 1; i >= 0; i--)
{
if (block.Instructions[i] is IfInstruction inst)
{
if (CachedDelegateInitializationWithField(inst))
{
block.Instructions.RemoveAt(i);
continue;
}
if (CachedDelegateInitializationWithLocal(inst))
{
ILInlining.InlineOneIfPossible(block, i, InliningOptions.Aggressive, context);
continue;
}
if (CachedDelegateInitializationRoslynInStaticWithLocal(inst) || CachedDelegateInitializationRoslynWithLocal(inst))
{
block.Instructions.RemoveAt(i);
continue;
}
}
}
}
public void Run(Block block, int pos, StatementTransformContext context)
{
if (!context.Settings.NamedArguments)
{
return;
}
var options = ILInlining.OptionsForBlock(block, pos, context);
options |= InliningOptions.IntroduceNamedArguments;
ILInlining.InlineOneIfPossible(block, pos, options, context: context);
}
/// <summary>
/// Handles NullCoalescingInstruction case 1: reference types.
///
/// stloc s(valueInst)
/// if (comp(ldloc s == ldnull)) {
/// stloc s(fallbackInst)
/// }
/// =>
/// stloc s(if.notnull(valueInst, fallbackInst))
/// </summary>
bool TransformRefTypes(Block block, int pos, StatementTransformContext context)
{
if (!(block.Instructions[pos] is StLoc stloc))
{
return(false);
}
if (stloc.Variable.Kind != VariableKind.StackSlot)
{
return(false);
}
if (!block.Instructions[pos + 1].MatchIfInstruction(out var condition, out var trueInst))
{
return(false);
}
if (!(condition.MatchCompEquals(out var left, out var right) && left.MatchLdLoc(stloc.Variable) && right.MatchLdNull()))
{
return(false);
}
trueInst = Block.Unwrap(trueInst);
if (trueInst.MatchStLoc(stloc.Variable, out var fallbackValue))
{
context.Step("NullCoalescingTransform: simple (reference types)", stloc);
stloc.Value = new NullCoalescingInstruction(NullCoalescingKind.Ref, stloc.Value, fallbackValue);
block.Instructions.RemoveAt(pos + 1); // remove if instruction
ILInlining.InlineOneIfPossible(block, pos, InliningOptions.None, context);
return(true);
}
// sometimes the compiler generates:
// stloc s(valueInst)
// if (comp(ldloc s == ldnull)) {
// stloc v(fallbackInst)
// stloc s(ldloc v)
// }
// v must be single-assign and single-use.
if (trueInst is Block trueBlock && trueBlock.Instructions.Count == 2 &&
trueBlock.Instructions[0].MatchStLoc(out var temporary, out fallbackValue) &&
temporary.IsSingleDefinition && temporary.LoadCount == 1 &&
trueBlock.Instructions[1].MatchStLoc(stloc.Variable, out var useOfTemporary) &&
useOfTemporary.MatchLdLoc(temporary))
{
context.Step("NullCoalescingTransform: with temporary variable (reference types)", stloc);
stloc.Value = new NullCoalescingInstruction(NullCoalescingKind.Ref, stloc.Value, fallbackValue);
block.Instructions.RemoveAt(pos + 1); // remove if instruction
ILInlining.InlineOneIfPossible(block, pos, InliningOptions.None, context);
return(true);
}
return(false);
}
