Today we continue reading the WRL research report  on Swift Java compiler. We were discussing register allocations and solving it by means of graph coloring. Today we continue with the order of coloring. The bias graph is used to make intelligent choices of a color from the set of legal colorings allowed by the interference graph. Uncolored nodes are colored the same as a node only if the Interim nodes can be colored the same. If the coloring does not succeed, then we spill values to the stack. The value corresponding to each node that was not colored is spilled onto the stack by inserting a spill value just after its definition and a restore value before each use.This lets the original value and the newly added restore value to be in a register over a shorter range and thus will be hopefully easier to color on the next pass.
A final cleanup pass is necessary after all the coloring succeeds  to remove copies that have the same source and destination and to remove unnecessary restore operations. This pass does a data flow computation to determine what value each register holds after each instruction. This helps with optimization such as replacing input value of each instruction with the oldest copy that is still in a register.
#codingexercise
GetAllNumberRangeProductCubeRootPowerSeven (Double [] A)
{
if (A == null) return 0;
Return A.AllNumberRangeProductCubeRootPowerSeven();
}
#codingexercise
GetAllNumberRangeProductCubeRootPowerNine) (Double [] A)
{
if (A == null) return 0;
Return A.AllNumberRangeProductCubeRootPowerNine();
}