One great way to visualize what is going on here is to take advantage of a -few LLC command line options. In particular, the -view-isel-dags -option pops up a window with the SelectionDAG input to the Select phase for all -of the code compiled (if you only get errors printed to the console while using -this, you probably need to configure -your system to add support for it). The -view-sched-dags option -views the SelectionDAG output from the Select phase and input to the Scheduler -phase. The -view-sunit-dags option views the ScheduleDAG, which is -based on the final SelectionDAG, with nodes that must be scheduled as a unit -bundled together into a single node, and with immediate operands and other -nodes that aren't relevent for scheduling omitted. +few LLC command line options. The following options pop up a window displaying +the SelectionDAG at specific times (if you only get errors printed to the console +while using this, you probably +need to configure your system to +add support for it).
+ +The -view-sunit-dags displays the Scheduler's dependency graph. +This graph is based on the final SelectionDAG, with nodes that must be +scheduled together bundled into a single scheduling-unit node, and with +immediate operands and other nodes that aren't relevent for scheduling +omitted.