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Modules and Compilers on Cirrus

Cirrus is an HPE Cray EX4000 system and use the Cray Programming Environment for managing compilers, MPI, and scientific libraries through a modular software system.

Module Commands

Command	Effect
`module avail`	List all available modules
`module load <name>`	Load a module into the current session
`module unload <name>`	Unload a module from the current session
`module list`	List all currently loaded modules
`module restore`	Switch back to default login environment module setup
`module spider <name>`	Search for a module and show details

Gotchas:

Users should never use module purge on Cirrus as it will break the Cray Programming Environment setup

Programming Environments

Available environments

module avail PrgEnv           # quick list
module spider PrgEnv       # detailed view

   PrgEnv-aocc/8.6.0    PrgEnv-cray/8.6.0 (L)    PrgEnv-gnu/8.6.0    PrgEnv-intel/8.6.0

PrgEnv-gnu is usually recommended — good performance, familiar behaviour, all dependencies loaded automatically:

module load PrgEnv-gnu
module list

Currently Loaded Modules:
  1) craype-x86-turin   3) craype-network-ofi       5) xpmem/1.0.1-1.5_1_gfb6998056825   7) epcc-setup-env     9) gcc-native/14.2  11) cray-dsmml/0.3.1   13) cray-libsci/25.03.0
  2) libfabric/2.3.1    4) perftools-base/25.03.0   6) cse_env/0.2                       8) load-epcc-module  10) craype/2.7.34    12) cray-mpich/8.1.32  14) PrgEnv-gnu/8.6.0

Key components loaded by PrgEnv-gnu:

Module	Purpose
`gcc-native/14.2`	GCC 14.2 compiler suite
`libfabric`	Communication library for Slingshot 11 high-speed interconnect
`cray-libsci`	Scientific and math libraries (BLAS, LAPACK, etc.)
`cray-mpich`	MPI libraries

Cray compiler wrappers

With a PrgEnv loaded, use the Cray compiler wrappers rather than invoking the compiler directly:

Wrapper	Language	GCC equivalent
`cc`	C	`gcc`
`CC`	C++	`g++`
`ftn`	Fortran	`gfortran`

The wrappers automatically link to loaded Cray PE libraries (MPI, LibSci, etc.). Do not mix wrapper commands and raw GCC commands in the same build.

To see exactly what the wrapper passes to the underlying compiler:

ftn -craype-verbose -o hello hello.f90
# Shows full flags, include paths, and linked libraries

Profiling Tools

gprof

Available once PrgEnv-gnu is loaded:

gprof ./my_application.x

Cray Perftools

module load perftools-base
pat_run ./my_application.x

Full docs: HPE Cray Performance Tools

Quick Reference

Goal	Command
Recommended build environment	`module load PrgEnv-gnu`
Compile C	`cc -O3 myfile.c`
Compile C++	`CC -O3 myfile.cpp`
Compile Fortran	`ftn -O3 myfile.f90`
Debug wrapper flags	`cc -craype-verbose ...`
Profile with Cray tools	`module load perftools-base` → `pat_run`
Spack builds	See Spack guide