/// <summary>
/// Defines the global variable that backs a vtable.
/// </summary>
/// <param name="Module">The module to declare the global in.</param>
/// <param name="Type">The type that owns the vtable.</param>
/// <param name="VTableEntryImpls">
/// The list of virtual function pointers in the vtable.
/// </param>
/// <returns>A vtable global variable.</returns>
public static LLVMValueRef DefineVTableGlobal(
LLVMModuleBuilder Module,
IType Type,
LLVMValueRef[] VTableEntryImpls)
{
var fields = new LLVMValueRef[3];
fields[0] = ConstInt(Int64Type(), Module.GetTypeId(Type), false);
fields[1] = ConstInt(Int64Type(), Module.GetTypeIndex(Type), false);
fields[2] = ConstArray(
PointerType(Int8Type(), 0),
VTableEntryImpls);
var vtableContents = ConstStruct(fields, false);
var vtable = Module.DeclareGlobal(
vtableContents.TypeOf(),
Type.FullName.ToString() + ".vtable");
vtable.SetGlobalConstant(true);
vtable.SetLinkage(LLVMLinkage.LLVMInternalLinkage);
vtable.SetInitializer(vtableContents);
return(vtable);
}
/// <summary>
/// Defines this stub's body.
/// </summary>
/// <param name="Module">The module that defines the stub.</param>
public void Emit(LLVMModuleBuilder Module)
{
var entryBlock = AppendBasicBlock(Function, "entry");
var defaultBlock = AppendBasicBlock(Function, "unknown_type");
var builder = CreateBuilder();
PositionBuilderAtEnd(builder, defaultBlock);
BuildUnreachable(builder);
DisposeBuilder(builder);
builder = CreateBuilder();
PositionBuilderAtEnd(builder, entryBlock);
var switchInstr = BuildSwitch(builder, GetParam(Function, 0), defaultBlock, (uint)impls.Count);
foreach (var pair in impls)
{
switchInstr.AddCase(
ConstInt(Int64Type(), (ulong)Module.GetTypeIndex(pair.Key), false),
WriteReturnBlock(pair.Key, pair.Value, Module));
}
DisposeBuilder(builder);
}
