Branch Instrumentation in SUIF

Conditional branches limit the speed of modern microprocessors. Researchers need tools to examine program branch behavior. HALT, the Harvard Atom-Like Tool, allows SUIF users to instrument conditional branch instructions in their programs. Instrumentation code enables research into the branch problem: how programs use conditional branches and how they can be handled efficiently during program execution. In particular, we use instrumentation to drive simulators of branch prediction hardware, to perform branch stream analysis, and to record statistics for profile-driven optimizations and code transformations. Predecessors of HALT and its downstream analysis phases have been the basis for our research in branch prediction.