[DDG][NFC] Colorize DDG dot graph (#181618)HEADmain

All blocks and edges are currently colored black which makes it
difficult to distinguish while looking at huge graph.

This simple patch implements the following colorization to make it
visually more distinguishable.

1. Pi-blocks - styled to rounded, filled, light-yellow fill, dark orange
border
2. Multi-instruction blocks - Light cyan fill
3. MemoryDependence edges are now colored red.
4. Register def-use edges are now colored blue.

This patch implements `getNodeAttributes()` to return the string of
attributes to apply to the node.

0 files changed, 0 insertions, 0 deletions