forwprop: Simplify long_mul_summand by using an array for hilo components.
forwprop: Replaces hilo{0,1,2} with an array, simplifying code and loop constructs.
The hilo{0,1,2} components within the long_mul_summand structure in forwprop have been converted into an array. This change streamlines the code, particularly for range-based for loops, by eliminating the need for a local array copy. The update also replaces direct hilo[n] access with array indexing and modifies the copy location to use a loop.
In Details
The long_mul_summand structure in tree-ssa-forwprop.cc previously used separate fields hilo0, hilo1, and hilo2 to store intermediate results for wide multiplication. This commit consolidates these into a hilo[3] array. This simplifies loop iterations and array accesses within the forward propagation pass, making the code cleaner and potentially more efficient.