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toolchain_common.md

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Common toolchain options

Optimization level

EasyBuild distinguishes between four optimization levels. Rather than having a single toolchain option that takes the level as a number, toolchainopts uses four boolean parameters where one takes precedence over others. Lower optimization takes precedence over higher optimization. All have as default value False yet defaultopt is the one that will be used if nothing is specified.

Option What?
noopt Disable compiler optimizations
lowopt Low compiler optimizations
defaultopt Default compiler optimizations
opt High compiler optimizations

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

Option What?
unroll Unroll loops (default: False)
optarch Enable architecture optimizations (default: False?)

TODO: Double-check what the optarch toolchain option is doing as there is also a different optarch parameter in the configuration files to specify compiler flags, or in the case of the CPE toolchains, target modules.

Floating point accuracy

There are five flags that set the floating point precision. All are False by default but defaultprec is taken if none of the options is set to True. Again, the first one that is set to True in the table below is used:

Option What?
strict Strict (highest) precision
precise High precision
defaultprec Default precision
loose Loose precision
veryloose Very loose precision

Other floating-point optimisation and accuracy-related flags:

Option What?
ieee Adhere to IEEE-754 rules (default: False)

Common parallelism-related options

Option What?
vectorize Enable compiler auto-vectorization, default except for noopt and lowopt
openmp Enable OpenMP (default: False)
usempi Use MPI compiler as default compiler (default: False)

The usempi option is only supported by toolchains that also include an MPI component.

Code generation and linking options

Option What?
32bit Compile 32bit target (default: False)
debug Enable debug (default: False)
pic Use PIC (default: False)
packed-linker-options No flag, internal to EasyBuild
shared Build shared library (default: False)
static Build static library (default: False)
rpath No flag, internal to EasyBuild

Source-related options

Option What?
cstd Specify C standard (C/C++ only - default: None)
i8 Integers are 8 byte integers (Fortran only - default: False)
r8 Real is 8 byte real (Fortran only - default: False)

Miscellaneous options

Option What?
verbose Verbose output (default: False)
cciscxx Use CC as CXX (default: False)
extra_cflags Specify extra CFLAGS options. (default: None)
extra_cxxflags Specify extra CXXFLAGS options. (default: None)
extra_f90flags Specify extra F90FLAGS options. (default: None)
extra_fcflags Specify extra FCFLAGS options. (default: None)
extra_fflags Specify extra FFLAGS options. (default: None)

Most of these options do not directly transform into compiler flags. Instead, they influence the way EasyBuild sets variables (cciscxx) or directly add additional flags to the indicated environment variables.