Editing Register allocation (section)

==== Pseudocode ====

This describes the algorithm as first proposed by Poletto et al.,{{sfn|Poletto|Sarkar|1999|p=899}} where:
* '''R''' is the number of available registers.
* '''active''' is the list, sorted in order of increasing end point, of live intervals overlapping the current point and placed in registers.

 '''LinearScanRegisterAllocation'''
     active ← {}
     '''for each''' live interval ''i'', in order of increasing start point '''do'''
         ExpireOldIntervals(i)
         '''if''' length(active) = R '''then'''
             SpillAtInterval(i)
         '''else'''
             register[i] ← a register removed from pool of free registers
             add ''i'' to active, sorted by increasing end point
 
 '''ExpireOldIntervals(i)'''
     '''for each''' interval ''j'' '''in''' active, in order of increasing end point '''do'''
         '''if''' endpoint[j] ≥ startpoint[i] '''then'''
             '''return''' 
         remove ''j'' from active
         add register[j] to pool of free registers
 
 '''SpillAtInterval(i)'''
     spill ← last interval in active
     '''if''' endpoint[spill] > endpoint[i] '''then'''
         register[i] ← register[spill]
         location[spill] ← new stack location
         remove spill from active
         add ''i'' to active, sorted by increasing end point
     '''else'''
         location[i] ← new stack location