LF95 Linux User's Guide - Lahey Computer Systems

Compiler and Linker OptionsThe -Keval option allows the compiler to apply optimizations by changing the order in whichexpressions are evaluated. Depending on program structure, it is possible that use of thisoption could alter program results. Use the --info option to determine if these optimizationswere applied.Use of the -Kfast option forces the -Keval option.-K[no]fapStorage of REAL and COMPLEX data types in hardware registersCompile only. Default: -KnofapThe -Knofap option causes REAL or COMPLEX variables of any kind to be stored in hardwareregisters whenever possible, and applies optimizations accordingly.The -Kfap option does not attempt to store REAL or COMPLEX variables in hardware registers.Optimization which assume hardware storage are not applied.-K[no]fp_relaxedFaster FP division and SQRT calculationCompile only. Default: -Knofp_relaxedWhen the -Kfp_relaxed option is specified, the compiler generates code that speeds floatingpoint division and SQRT calculations at the cost of greater rounding error. Compared to normalcalculation, calculations made with -Kfp_relaxed will differ by 1 or 2 bits.-K[no]fsimpleSimplify floating point operationsCompile only. Default: -KnofsimpleThe -Kfsimple option allows the compiler to simplify floating point expressions. For example,the expression x*1. might be simplified to x.Use of the -Keval option forces -Kfsimple.-K[no]fuseLoop fusionCompile only. Default: -KnofuseThe -Kfuse option allows the compiler to perform loop fusion optimizations.The -Kfuse option is only valid at optimization levels --o2 or --o3.-K[no]loopLoop structure modificationCompile only. Default: -KnoloopThe -Kloop option allows the compiler to perform optimizations that involve modification ofloop structure.Lahey/Fujitsu Linux64 Fortran User’s Guide 27