Method Build

src/common/scripting/backend/vmbuilder.cpp:839–971

void FFunctionBuildList::Build()
{
	VMDisassemblyDumper disasmdump(VMDisassemblyDumper::Overwrite);

	for (auto &item : mItems)
	{
		// [Player701] Do not emit code for abstract functions
		bool isAbstract = item.Func->Variants[0].Implementation->VarFlags & VARF_Abstract;
		if (isAbstract) continue;

		assert(item.Code != NULL);

		// We don't know the return type in advance for anonymous functions.
		FCompileContext ctx(item.CurGlobals, item.Func, item.Func->SymbolName == NAME_None ? nullptr : item.Func->Variants[0].Proto, item.FromDecorate, item.StateIndex, item.StateCount, item.Lump, item.Version);

		// Allocate registers for the function's arguments and create local variable nodes before starting to resolve it.
		VMFunctionBuilder buildit(item.Func->GetImplicitArgs());
		for (unsigned i = 0; i < item.Func->Variants[0].Proto->ArgumentTypes.Size(); i++)
		{
			auto type = item.Func->Variants[0].Proto->ArgumentTypes[i];
			auto name = item.Func->Variants[0].ArgNames[i];
			auto flags = item.Func->Variants[0].ArgFlags[i];
			// this won't get resolved and won't get emitted. It is only needed so that the code generator can retrieve the necessary info about this argument to do its work.
			auto local = new FxLocalVariableDeclaration(type, name, nullptr, flags, FScriptPosition());
			if (!(flags & VARF_Out)) local->RegNum = buildit.Registers[type->GetRegType()].Get(type->GetRegCount());
			else local->RegNum = buildit.Registers[REGT_POINTER].Get(1);
			ctx.FunctionArgs.Push(local);
		}

		FScriptPosition::StrictErrors = !item.FromDecorate || strictdecorate;
		item.Code = item.Code->Resolve(ctx);
		// If we need extra space, load the frame pointer into a register so that we do not have to call the wasteful LFP instruction more than once.
		if (item.Function->ExtraSpace > 0)
		{
			buildit.FramePointer = ExpEmit(&buildit, REGT_POINTER);
			buildit.FramePointer.Fixed = true;
			buildit.Emit(OP_LFP, buildit.FramePointer.RegNum);
		}

		// Make sure resolving it didn't obliterate it.
		if (item.Code != nullptr)
		{
			if (!item.Code->CheckReturn())
			{
				if (ctx.ReturnProto == nullptr || !ctx.ReturnProto->ReturnTypes.Size())
				{
					auto newcmpd = new FxCompoundStatement(item.Code->ScriptPosition);
					newcmpd->Add(item.Code);
					newcmpd->Add(new FxReturnStatement(nullptr, item.Code->ScriptPosition));
					item.Code = newcmpd->Resolve(ctx);
				}
				else
				{
					item.Code->ScriptPosition.Message(MSG_ERROR, "Missing return statement in %s", item.PrintableName.GetChars());
					continue;
				}
			}