Improving virtual function call target prediction via dependence-based pre-computation

We introduce dependence-based pre-computation as a complement to history-based target prediction schemes. We present pre-computation in the context of virtual function calls (v-calls), a class of control transfers that is becoming increasingly important and has resisted conventional prediction. Our proposed technique dynamically identifies the sequence of operations that computes a v-call’s target. When the first instruction in such a sequence is encountered, a small execution engine speculatively and aggressively pre-executes the rest. The pre-computed target is stored and subsequently used when a prediction needs to be made. We show that a common v-call instruction sequence can be exploited to implement pre-computation using a previously proposed prefetching mechanism and minimal additional hardware. In a suite of C++ programs, dependence-based pre-computation eliminates 46% of the mispredictions incurred by a simple BTB and 24% of those associated with a path-based two-level pr...

• Type: Conference
• Year: 1999
• Where: ICS
• Authors: Amir Roth, Andreas Moshovos, Gurindar S. Sohi
• Keywords: Dependence-based Pre-computation, Distributed And Parallel Computing, History-based Target Prediction, ICS 1999, V-call Instruction Sequence