O
- object files
- compile only, 3.4.7 –c
- name, 3.4.66 –o filename
- object library search directories, 3.4.48 –Lpath
- object-oriented Fortran, 4.6.13 Object-Oriented Fortran Support
- obsolete command-line options, 3.3.4 Obsolete Option Flags
- octal, 4.2.1.2 Alternate Forms of Boolean Constants
- OMP_NUM_THREADS, number of threads
- 3.4.4 –autopar
- 3.4.145 –xopenmp[={parallel|noopt|none}]
- one-trip DO loops, 3.4.67 –onetrip
- OpenMP, 2.3.2.1 OpenMP Parallelization Directives
- directives summary, C.3 Fortran OpenMP Directives
- OPT directive, 2.3.1.5 The OPT Directive
- -xmaxopt option, 3.4.138 –xmaxopt[=n]
- optimization
- across source files, 3.4.124 –xipo[={0|1|2}]
- aliasing, 3.4.102 –xalias[=keywords]
- floating-point, 3.4.34 –fsimple[={1|2|0}]
- inline user-written routines, 3.4.43 –inline=[%auto][[,][no%]f1,…[no%]fn]
- interprocedural, 3.4.124 –xipo[={0|1|2}]
- levels, 3.4.65 –O[n]
- link-time, 3.4.136 –xlinkopt[={1|2|0}]
- loop unrolling, 3.4.91 –unroll=n
- loop unrolling by directive, 2.3.1.3 The UNROLL Directive
- math library, 3.4.134 –xlibmopt
- OPT directive
- 2.3.1.5 The OPT Directive
- 3.4.138 –xmaxopt[=n]
- PIPELOOP directive, 2.3.1.6 The PIPELOOP[=n] Directive
- PREFETCH directive, 2.3.1.7 The PREFETCH Directives
- specify cache, 3.4.108 –xcache=c
- specify instruction set architecture, 3.4.104 –xarch=isa
- specify processor, 3.4.110 –xchip=c
- target hardware, 3.4.57 –native
- with debugging, 3.4.38 –g
- with -fast, 3.4.23 –fast
- options, See command-line options
- order of, functions, 3.4.115 –xF
- order of processing, options, 3.2 Options Syntax
- overflow
- stack, 3.4.83 –stackvar
- trap on floating-point, 3.4.36 –ftrap=t
- overindexing, aliasing, 3.4.102 –xalias[=keywords]