Using Flang

Compiler Options

For a list of compiler options, enter

% flang -help

The Flang compiler supports accepts all clang 4.0 compiler options and supports many, as well as the following flang-specific compiler options:

• -noFlangLibs Do not link against Flang libraries
• -mp Enable OpenMP and link with with OpenMP library libomp
• -nomp Do not link with OpenMP library libomp
• -Mbackslash Treat backslash character like a C-style escape character
• -Mno-backslash Treat backslash like any other character
• -Mbyteswapio Swap byte-order for unformatted input/output
• -Mfixed Assume fixed-format source
• -Mextend Allow source lines up to 132 characters
• -Mfreeform Assume free-format source
• -Mpreprocess Run preprocessor for Fortran files
• -Mrecursive Generate code to allow recursive subprograms
• -Mstandard Check standard conformance
• -Msave Assume all variables have SAVE attribute
• -module path to module file (-I also works)
• -Mallocatable=95 Select Fortran 95 semantics for assignments to allocatable objects (Default)
• -Mallocatable=03 Select Fortran 03 semantics for assignments to allocatable objects
• -static-flang-libs Link using static Flang libraries
• -M[no]daz Treat denormalized numbers as zero
• -M[no]flushz Set SSE to flush-to-zero mode
• -Mcache_align Align large objects on cache-line boundaries
• -M[no]fprelaxed This option is ignored
• -fdefault-integer-8 Treat INTEGER and LOGICAL as INTEGER8 and LOGICAL8
• -fdefault-real-8 Treat REAL as REAL*8
• -i8 Treat INTEGER and LOGICAL as INTEGER8 and LOGICAL8
• -r8 Treat REAL as REAL*8
• -fno-fortran-main Don't link in Fortran main