Removing anti dependences by repairing

Abstract

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