Today we continue to discuss the WRL research report on Swift Java compiler. We were discussing  Trace scheduling and we saw that it involves a greedy algorithm. We will now continue with block layout how Swift uses profile information to determine a good layout for the traces.Swift uses  a simple version of Pettis and Hansen's code layout algorithm. This is also a greedy algorithm that gradually merges blocks/traces into sequences. and always merges the two sequences that have the heaviest weight edge between an element of one and the element of the other. The end result of this algorithm is a single merged sequence which is the desired layout.
The changes that Swift makes ensures that loop exit block will be placed at the end of a loop/ Swift also modifies the dynamic or static profile information such as by reducing the weight of other outgoing edges of a block which has an edge that exits a loop. By keeping the exit at the end, Swift  guarantees only one branch per loop iteration. Branches that exit in the middle are given lower priority since these edges are already determined to be less important than the remaining edges in a tree.
#codingexercise
GetAllNumberRangeProductCubeRootPowerFour) (Double [] A)
{
if (A == null) return 0;

Return A.AllNumberRangeProductCubeRootPowerFour();


}