Control Speculation in Multithreaded Processors through Dynamic Loop Detection

This paper presents a mechanism to dynamically detect the loops that are executed in a program. This technique detects the beginning and the termination of the iterations and executions of the loops without compiler/user intervention. We propose to apply this dynamic loop detection to the speculation of multiple threads of control dynamically obtained from a sequential program. Based on the highly predictable behavior of the loops, the history of the past executed loops is used to speculate the future dynamic instruction sequence. The overall objective is to dynamically obtain coarse grain parallelism (at the thread level) that can be exploited by a multithreaded architecture. We show that for a 4-context multithreaded processor, the speculation mechanism provides around 3 concurrent threads in average. Keywords: control speculation, multithreaded architectures, dynamic loop detection, instruction level parallelism. 1 INTRODUCTION Control speculation increases the potential paralleli..