Method select

src/VariableSelector.cpp:1171–1229

-------------------------------------------------------------- Select or Create a new variable visible to this scope (new var may be global, or local to one of the function's blocks)

// Select or Create a new variable visible to this scope (new var may be
// global, or local to one of the function's blocks)
Variable *
VariableSelector::select(Effect::Access access,
			   const CGContext &cg_context,
               const Type* type,
			   const CVQualifiers* qfer,
			   const vector<const Variable*>& invalid_vars,
			   eMatchType mt, eVariableScope scope)
{
	DEPTH_GUARD_BY_TYPE_RETURN_WITH_FLAG(dtSelectVariable, scope, NULL);
	VariableSelectFilter filter(cg_context);
	if (scope == MAX_VAR_SCOPE) {
		scope = VariableSelectionProbability(scope, &filter);
	}
	ERROR_GUARD(NULL);
	Variable *var = 0;
	var_created = false;

	// Note that many of the functions that select `var' can return null, if
	// they cannot find a suitable variable.  So we loop.
	switch (scope) {
	case eGlobal:
		var = SelectGlobal(access, cg_context, type, qfer, mt, invalid_vars);
		break;
	case eParentLocal:
		// ...a local var from one of its blocks.
		var = SelectParentLocal(access, cg_context, type, qfer, mt, invalid_vars);
		break;
	case eParentParam:
		// ...one of the function's parameters.
		var = SelectParentParam(access, cg_context, type, qfer, mt, invalid_vars);
		break;
	case eNewValue:
		// Must decide where to put the new variable (global or parent
		// local)?
		var = GenerateNewVariable(access, cg_context, type, qfer);
		if (CGOptions::expand_struct())
			Error::set_error(ERROR);
		break;
	case MAX_VAR_SCOPE:
		assert (0);
	}
	ERROR_GUARD(NULL);
	if (var && !cg_context.get_effect_context().is_side_effect_free()) {
		assert(!var->is_volatile());
	}
	// record statistics
	if (var) {
		if (var_created) {
			const Type* t = var->type;
			Bookkeeper::use_new_var_cnt++;
			Bookkeeper::record_vars_with_bitfields(t);
			incr_counter(Bookkeeper::struct_depth_cnts, t->get_struct_depth());
			if (t->eType == eUnion) Bookkeeper::union_var_cnt++;
		} else {
			Bookkeeper::use_old_var_cnt++;
		}
	}
	return var;