METHOD AND SYSTEM FOR TARGET REGISTER ALLOCATION

A computer-based method and system for allocating target registers to branch operations and for determining the location of target definitions for the branch operations within a computer program. The target register allocation system of the present invention allocates a target register to be specified by each branch operation. The target register is to contain the address of the target that is loaded by the target definition. The target register allocation system determines a location in the computer program for a target definition such that whenever the branch operation is executed, the allocated target register contains the address of the target of the branch. The target allocation system may determine the location to be in a dominator block of the branch operation. The target allocation system may also determine the location a target definition so that the address of the target that is loaded by the target definition can be used by multiple branch operations. The target allocation system may also determine the location of the target definition based on execution frequency of locations. The target allocation system may, when a branch operation is in a loop, determine the location of the target definition to be outside the loop. The target allocation system may, when the program is a function, give preference to a non-callee save register in allocating a target register. The target allocation system may give preference to a callee save register of a function whose invocation is located in between the determined location and the location of the branch operation on a path of execution when allocating a target register. La présente invention concerne un procédé et un système automatisés servant à affecter des registres cibles à des opérations de branchement et à déterminer l'emplacement de définitions cibles pour les opérations de branchement dans un programme informatique. Le système d'affectation de registres cibles de l'invention affecte un registre cible devant être spécifié par chaque opération de branchement. Le registre cible doit contenir l'adresse de la cible qui est chargée par la définition cible. Le système d'affectation de registres cibles détermine un emplacement dans le programme informatique pour une définition cible de manière que chaque fois que l'opération de branchement est exécutée, le registre cible affecté contient l'adresse de la cible du branchement. Le système d'affectation de cible peut déterminer cet emplacement dans un bloc domin