Wish Branches: Enabling Adaptive and Aggressive Predicated Execution

We propose a mechanism in which the compiler generates code that can be executed either as predicated code or nonpredicated code. The compiler-generated code is the same as predicated code, except the predicated conditional branches are not removed - they are left intact in the program code. These conditional branches are called wish branches. The goal of wish branches is to use predicated execution for hard-to-predict dynamic branches, and branch prediction for easy-to-predict dynamic branches, thereby obtaining the best of both worlds. Wish loops, one class of wish branches, use predication to reduce the misprediction penalty for hard-to-predict backward (loop) branches