Method makeInferenceNode

src/jrd/optimizer/Optimizer.cpp:3367–3404

//

BoolExprNode* Optimizer::makeInferenceNode(BoolExprNode* boolean,
										   ValueExprNode* arg1,
										   ValueExprNode* arg2)
{
	const auto cmpNode = nodeAs<ComparativeBoolNode>(boolean);
	fb_assert(cmpNode);	// see our caller

	// Clone the input predicate
	const auto newCmpNode =
		FB_NEW_POOL(getPool()) ComparativeBoolNode(getPool(), cmpNode->blrOp);

	// We may safely copy invariantness flag because
	// (1) we only distribute field equalities
	// (2) invariantness of second argument of STARTING WITH or LIKE is solely
	//    determined by its dependency on any of the fields
	// If provisions above change the line below will have to be modified
	newCmpNode->nodFlags = cmpNode->nodFlags;

	// Share impure area for cached invariant value used to hold pre-compiled
	// pattern for new LIKE and CONTAINING algorithms.
	// Cached pattern matcher also should be shared by both nodes, else new node
	// could overwrite impure area at offset zero. See bug GH-7276.
	// Proper cloning of impure area for this node would require careful accounting
	// of new invariant dependencies - we avoid such hassles via using single
	// cached pattern value for all node clones. This is faster too.
	if (newCmpNode->nodFlags & (ExprNode::FLAG_INVARIANT | ExprNode::FLAG_PATTERN_MATCHER_CACHE))
		newCmpNode->impureOffset = cmpNode->impureOffset;

	// But substitute new values for some of the predicate arguments
	newCmpNode->arg1 = CMP_clone_node_opt(tdbb, csb, arg1);
	newCmpNode->arg2 = CMP_clone_node_opt(tdbb, csb, arg2);

	// Arguments after the first two are just cloned (eg: LIKE ESCAPE clause)
	if (cmpNode->arg3)
		newCmpNode->arg3 = CMP_clone_node_opt(tdbb, csb, cmpNode->arg3);

	return newCmpNode;
}


BoolExprNode* Optimizer::makeInferenceNode(BoolExprNode* boolean,