lDtrace — A Tracing Tool for i486 Simulation

This technical report describes IDtrace, a program that produces execution traces for ix86 instruction set architectures using late-code modification. IDtrace provides a low cost method for producing input data for a wide variety of performance evaluation tools such as code profilers, branch prediction simulators, and cache simulators. IDtrace can generate several types of output traces: profile, branch, memory refer-ence, and full execution traces. It currently runs on ix86 SysVR4 Unix systems. The report briefly introduces various trace generation methods and discusses the advantages and disad-vantages of late code modification over other code instrumentation techniques. The majority of the report describes the use of IDtrace and outlines the formats for all generated trace files. In addition, the issues involved in constructing such an instrumentation tool, including the challenges imposed by the i486’s CISC-like features, are discussed. Architectural attributes such as the large number of memory referencing instructions, the complex instructions and addressing modes, and the variable instruction lengths make instrumentation difficult and sometimes impossible at the binary level. These problems and their possible solutions are discussed. Finally, the report includes some experimental results to illustrate the applicability of IDtrace. Th