AddKindArg adds to args the appropriate GCC argument for achieving the compile kind mentioned in k.

AddStringArg adds the argument '-[k][v]' (note lack of equals sign) to args if v is non-blank; else, returns args.

Args computes the arguments to pass to GCC for running job j.

MOpts gets the default 'm' invocations (march, mcpu, etc.) to consider for compilers with archID arch.

OptLevelDisabledNames contains optimisation levels that are disabled by default, as they are redundant or non-portable.

OptLevelNames is a consistently named list of the optimisation levels in OptLevels.

OptLevels contains the optimisation levels known to exist on GCC, Clang, AppleClang etc.

GCC represents GCC-style compilers such as GCC and Clang.