2.4.3 Statement-wise First and Last Depths to Optimize Control options->fs, options->ls

option->f/l (command-line arguments: -f and -l) provide first and last levels to optimize control overhead at a global level (across the entire program / all statements) by separating / splitting loops. option->fs/ls allow the equivalent of setting -f/-l options on a statement-wise basis. Integer arrays options->fs, options->ls should be allocated by the user with options->fs_ls_size set to the number of elements (always equal to the number of statements). For any given loop, the first and last depths of all statements under it are looked at to determine if the loop should be separated (max across all fs’ and ls’ is taken). A user has to set fs meaningfully, i.e., for eg., if two statements i & j have a fused loop and fs[i], fs[j] specify separation for that level for stmt i but not for stmt j, the input is ambiguous and we will in this case not separate (since a max is taken). options->fs/ls override f/l; if fs/ls are not set or are set inconsistently (max across ls[i] < max across fs[i]), f/l take over.

fs/ls can only be set via the library interface for now.

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