Removing Anti Dependences by Repairing

Abstract. Anti dependences (write-after-read dependences) constrain the reordering of instructions and limit the eectiveness of instruction scheduling and software pipelining techniques for superscalar and VLIW processors. Repairing solves this problem: If the denition of a variable is moved before a previous use of that variable, compiler-generated re-pair code reconstructs the value that the denition destroyed. Repair-ing features several potential advantages over register renaming, another technique for removing anti dependences: less register pressure, less loop unrolling and fewer move instructions