/// <summary>
/// Lowers leae nodes to linear <see cref="LoadElementAddress"/> values.
/// </summary>
private static void Lower(
RewriterContext context,
TypeLowering <ArrayType> typeLowering,
LoadArrayElementAddress value)
{
var builder = context.Builder;
var location = value.Location;
Value array = value.ArrayValue;
// Get and validate the array type
var structureType = array.Type.As <StructureType>(location);
// Compute linear address based on the .Net array layouts
Value elementIndex = builder.CreatePrimitiveValue(location, 0L);
// (((0 * Width + x) * Height) + y) * Depth + z...
for (int i = 0, e = structureType.NumFields - 1; i < e; ++i)
{
Value length = builder.CreateGetField(
location,
array,
new FieldAccess(1 + i));
// Create a debug assertion to check for out-of-bounds accesses
builder.CreateDebugAssert(
location,
builder.CreateCompare(
location,
value.Dimensions[i],
length,
CompareKind.LessThan),
builder.CreatePrimitiveValue(
location,
$"{i}-th array index out of range"));
// Update index computation
elementIndex = builder.CreateArithmetic(
location,
elementIndex,
length,
BinaryArithmeticKind.Mul);
elementIndex = builder.CreateArithmetic(
location,
elementIndex,
value.Dimensions[i],
BinaryArithmeticKind.Add);
}
// Extract the actual view field from the structure and compute the
// appropriate target element address.
var view = GetViewFromArray(builder, location, array);
var lea = builder.CreateLoadElementAddress(
location,
view,
elementIndex);
context.ReplaceAndRemove(value, lea);
}
/// <summary cref="IValueVisitor.Visit(LoadArrayElementAddress)"/> public void Visit(LoadArrayElementAddress value) => throw new InvalidCodeGenerationException();
