under Contract DABT63-95-C-0127 and ARPA order no. D346. The current support for this work comes from a variety of sources, all of to which we are indebted.

University of Wisconsin-Madison Computer Sciences Department Technical Report #1342, June, 1997.

The SimpleScalar Tool Set, Version 2.0

Doug Burger*

Computer Sciences DepartmentUniversity of Wisconsin-Madison

1210 West Dayton StreetMadison, Wisconsin 53706 USA

Todd M. Austin

MicroComputer Research Labs, JF3-359Intel Corporation, 2111 NE 25th Avenue

Hillsboro, OR 97124 USA

*Contact: dburger@cs.wisc.edu

http://www.cs.wisc.edu/~mscalar/simplescalar.html

This report describes release 2.0 of the SimpleScalar tool set,a suite of free, publicly available simulation tools that offer bothdetailed and high-performance simulation of modern micropro-cessors. The new release offers more tools and capabilities, pre-compiled binaries, cleaner interfaces, better documentation,easier installation, improved portability, and higher perfor-mance. This report contains a complete description of the toolset, including retrieval and installation instructions, a descrip-tion of how to use the tools, a description of the target SimpleS-calar architecture, and many details about the internals of thetools and how to customize them. With this guide, the tool set canbe brought up and generating results in under an hour (on sup-ported platforms).

easy annotation of instructions, without requiring a retargetedcompiler for incremental changes. The instruction de nitionmethod, along with the ported GNU tools, makes new simulatorseasy to write, and the old ones even simpler to extend. Finally,the simulators have been aggressively tuned for performance,and can run codes approaching “real” sizes in tractable amountsof time. On a 200-MHz Pentium Pro, the fastest, least detailedsimulator simulates about four million machine cycles per sec-ond, whereas the most detailed processor simulator simulatesabout 150,000 per second.

The current release (version 2.0) of the tools is a majorimprovement over the previous release. Compared to version 1.0[2], this release includes better documentation, enhanced perfor-mance, compatibility with more platforms, precompiled SPEC95SimpleScalar binaries, cleaner interfaces, two new processorsimulators, option and statistic management packages, a source-level debugger (DLite!) and a tool to trace the out-of-order pipe-line.

The rest of this document contains information about obtain-ing, installing, running, using, and modifying the tool set. InSection2 we provide a detailed procedure for downloading therelease, installing it, and getting it up and running. In Section3,we describe the SimpleScalar architecture and details about thetarget (simulated) system. In Section4, we describe the SimpleS-calar processor simulators and discuss their internal workings. InSection5, we describe two tools that enhance the utility of thetool set: a pipeline tracer and a source-level debugger (for step-ping through the program being simulated). In Section6, we pro-vide the history of the tools’ development, describe current andplanned efforts to extend the tool set, and conclude. InAppendixA and AppendixB contain detailed de nitions of theSimpleScalar instructions and system calls, respectively.

1 Overview

Modern processors are incredibly complex marvels of engi-neering that are becoming increasingly hard to evaluate. Thisreport describes the SimpleScalar tool set (release 2.0), whichperforms fast, exible, and accurate simulation of modern pro-cessors that implement the SimpleScalar architecture (a closederivative of the MIPS architecture [4]). The tool set takes bina-ries compiled for the SimpleScalar architecture and simulatestheir execution on one of several provided processor simulators.We provide sets of precompiled binaries (including SPEC95),plus a modi ed version of GNU GCC (with associated utilities)that allows you to compile your own SimpleScalar test binariesfrom FORTRAN or C code.

The advantages of the SimpleScalar tools are high exibility,portability, extensibility, and performance. We include ve exe-cution-driven processor simulators in the release. They rangefrom an extremely fast functional simulator to a detailed, out-of-order issue, superscalar processor simulator that supports non-blocking caches and speculative execution.

The tool set is portable, requiring only that the GNU toolsmay be installed on the host system. The tool set has been testedextensively on many platforms (listed in Section2). The tool setis easily extensible. We designed the instruction set to support

This work was initially supported by NSF Grants CCR-9303030, CCR-9509589, and MIP-9505853, ONR Grant N00014-93-1-0465, a donationfrom Intel Corp., and by U.S. Army Intelligence Center and Fort Hua-chuca under Contract DABT63-95-C-0127 and ARPA order no. D346.The current support for this work comes from a variety of sources, all ofto which we are indebted.

2 Installation and Use

The only restrictions on using and distributing the tool set arethat (1) the copyright notice must accompany all re-releases ofthe tool set, and (2) third parties (i.e., you) are forbidden to placeany additional distribution restrictions on extensions to the toolset that you release. The copyright notice can be found in the dis-tribution directory as well as at the head of all simulator source les. We have included the copyright here as well:

Copyright (C) 1994, 1995, 1996, 1997 by Todd M. Austin