The CFG view of difference graphs can be useful to get a quick grasp of where certain changes have happened between two phases. However, the current view has two issues that limit its usefulness: nodes are not properly scheduled within blocks, and the internal placeholder block for nodes without a real block (e.g. the top Con node when it is not used) is actually shown. This RFE proposes addressing these issues.

The attached screenshot illustrates the mentioned issues. To reproduce them, run:
$ java -Xbatch -XX:PrintIdealGraphLevel=3 -XX:CompileOnly=java.lang.Byte::toUnsignedInt
on a debug build, then open the difference graph between 14. and 15, and click on "Show control-flow graph".