cpeAMD toolchain¶

Note: The options are for the aocc.py file included in this repository and are not the same as those for the repository at CSCS.

Note about the compilers¶

AMD/ROCm 5.0.2 is based on LLVM 14.0.0

Available options¶

The cpeAMD toolchain supports the common toolchain options, the additional AMD flags and some additional Cray-specific flags, two of which are really just redefinitions of standard compiler flags.

Default toolchain options that may not behave as expected¶

rpath: rpath linking in EasyBuild has not been properly tested in the HPE Cray PE.
unroll: As it is not clear from the docunentation for the Fortran compiler which options should be set to enable or disable (if any at all)

AMD-specific toolchain options¶

Option	Categorie	What?
lto	code generation	Enable Link Time Optimization (in the default 'full' mode)
offload-lto	code generation	Enable LTO for offload compilation (in the default 'full' mode)

cpeAMD-specific flags (coming from the HPE Cray PE compiler wrappers)¶

Option	Categorie	What?
dynamic	code generation	Generate dynamically linked executable (default: True)
mpich-mt	parallelism	Alternate Cray-MPICH library for MT support (default: False)

mpich-mt: Directs the driver to link in an alternate version of the Cray-MPICH library which provides fine-grained multi-threading support to applications that perform MPI operations within threaded regions. (default: False)

Two further options trigger different compiler flags than in the GCC toolchain: verbose and optarch but have otherwise the same meaning.

Mapping of options onto compiler flags¶

Compiler optimization level¶

The common options translate into:

Option	Flag
noopt	-O0
lowopt	-O1
defaultopt	-O2 -fvectorize -fslp-vectorize
opt	-O3

Other optimization-related options (and see also parallelism below):

Option	Flag
unroll	-funroll-loops
optarch	TODO

Floating point precision¶

The decision of our mapping is based partly on information from Cray and partly on looking through various manuals on Clang.

Level strict: We simply stick to -ffp-model=strict. This automatically disables all of the -ffast-math enablements so there is no need to add -fno-fast-math. Note that at this level, fused multiply adds are disabled.
Level precise: We stick to -ffp-model=precise and add -ffp-contract=fast-honor-pragmas.
Default level: Currently the same as strict.
Level loose: Set to -ffp-model=fast but try to turn on again a few safeguards: -ffp-contract=fast-honor-pragmas, -fhonor-infinities, -fhonor-nans, -fsigned-zeros.
Level veryloose: Set to -ffp-model=fast

Note: Very recnet versions of clang add -ffp-contract=fast-honor-pragmas which may be interesting to add to precise, defaultprec and loose but is not yet supported by AOCC 2.2.

Option	Flag
strict	-ffp-model=strict
precise	-ffp-model=precise
defaultprec	-ffp-model=precise
loose	-ffp-model=fast -fhonor-infinities -fhonor-nans -fsigned-zeros
veryloose	-ffp-model=fast

Other floating-point optimisation and accuracy-related flags:

Option	What?
ieee	Not supported in clang/flang

Option	Flag
vectorize	False: -fno-vectorize -fno-slp-vectorize
	True: -fvectorize -fslp-vectorize
loop	-ftree-switch-conversion -floop-interchange -floop-strip-mine -floop-block
openmp	-fopenmp
usempi	No compiler flags
mpich-mt	-craympich-mt

Code generation and linking options¶

Option	Flag
dynamic	No flag as this is currently the only mode supported
lto	-flto
offload-lto	-foffload-lto
32bit	-m32
debug	-g
pic	-fPIC
packed-linker-options	Pack the linker options as comma separated list (default: False)
shared	-shared
static	-static
rpath	Use RPATH wrappers when --rpath is enabled in EasyBuild configuration (default: True)

NOTE: rpath has not yet been checked and is likely broken. There is a better way to do this in the /hPE Cray PE than what EasyBuild does as the wrappers already support rpath linking.

Option	Flag
cstd	-std=%(value)s
i8	-fdefault-integer-8
r8	-fdefault-real-8
f2c	-ff2c

Miscellaneous options¶

Option	Flag
verbose	-craype-verbose