CSUS-LLVM / OptSched

Optimizing scheduler. Combinatorial instruction scheduling project.

OptSched - Optimizing Scheduler

Combinatorial instruction scheduling research project at CSU Sacramento.

This plugin for the LLVM compiler is an optional machine scheduler. We implement a branch and bound instruction scheduling algorithm.

Requirements

• Ubuntu 16.04 (recommended), or MacOS 10.14
• CMake 3.4.3 or later
• LLVM 6.0 or later

Building

See BUILD.md for build instructions.

The OptSched plugin can be found in “llvm/lib” after building.

Configuration files

OptSched reads from configuration files at runtime to initialize the scheduler. There are templates in the example directory. The default search location for these files is ~/.optsched-cfg. You can optionally specify the path to this directory or any of the configuration files individually with command-line options.

Usage Examples

clang++ -O3 -fplugin=<path/to/OptSched.so> -mllvm -misched=optsched -mllvm -optsched-cfg=<path/to/optsched-cfg> <example.cpp>

llc -load <path/to/OptSched.so> -misched=optsched -optsched-cfg=<path/to/optsched-cfg> <example.ll>

Command-Line Options

When using Clang, pass options to LLVM with -mllvm.

CL Opt	Description
-enable-misched	Enable the machine scheduling pass in LLVM (Targets can override this option).
-misched=optsched	Select the optimizing scheduler.
-debug-only=optsched	Print debug information from the scheduler.
-optsched-cfg=<string>	Path to the directory containing configuration files for opt-sched.
-optsched-cfg-hotfuncs=<string>	Path to the list of hot functions to schedule using opt-sched.
-optsched-cfg-machine-model=<string>	Path to the machine model specification file for opt-sched.
-optsched-cfg-sched=<string>	Path to the scheduler options configuration file for opt-sched.