/// <summary>
/// Constructs a new phi builder.
/// </summary>
/// <param name="phiValue">The phi value.</param>
internal Builder(PhiValue phiValue)
{
Debug.Assert(phiValue != null, "Invalid phi value");
PhiValue = phiValue;
arguments = ImmutableArray.CreateBuilder <ValueReference>();
}
/// <summary>
/// Constructs a new phi builder.
/// </summary>
/// <param name="phiValue">The phi value.</param>
/// <param name="capacity">The initial capacity.</param>
internal Builder(PhiValue phiValue, int capacity)
{
Debug.Assert(phiValue != null, "Invalid phi value");
PhiValue = phiValue;
arguments = ValueList.Create(capacity);
argumentBlocks = BlockList.Create(capacity);
}
public readonly bool TryRemap(
PhiValue phiValue,
BasicBlock block,
out BasicBlock newBlock)
{
newBlock = block == OldBlock ? NewBlock : block;
return(true);
}
/// <summary>
/// Tries to remove a trivial phi value.
/// </summary>
/// <param name="methodBuilder">The current method builder.</param>
/// <param name="phiValue">The phi value to check.</param>
/// <returns>The resolved value.</returns>
public static Value TryRemoveTrivialPhi(
Method.Builder methodBuilder,
PhiValue phiValue)
{
// Implements a part of the SSA-construction algorithm from the paper:
// Simple and Efficient Construction of Static Single Assignment Form
// See also: SSABuilder.cs
Debug.Assert(phiValue != null, "Invalid phi value to remove");
Value same = null;
foreach (Value argument in phiValue.Nodes)
{
if (same == argument || argument == phiValue)
{
continue;
}
if (same != null)
{
return(phiValue);
}
same = argument;
}
// Unreachable phi
if (same == null)
{
return(phiValue);
}
var uses = phiValue.Uses.Clone();
phiValue.Replace(same);
// Remove the phi node from the current block
var builder = methodBuilder[phiValue.BasicBlock];
builder.Remove(phiValue);
foreach (var use in uses)
{
if (use.Resolve() is PhiValue usedPhi)
{
TryRemoveTrivialPhi(methodBuilder, usedPhi);
}
}
return(same);
}
public readonly bool CanRemap(PhiValue phiValue) => phiValue.Sources.Contains(OldBlock, new BasicBlock.Comparer());
/// <summary>
/// Returns the value of <paramref name="value"/>.
/// </summary>
public readonly Value RemapValue(
PhiValue phiValue,
BasicBlock updatedBlock,
Value value) =>
value;