On 2015.04.10 at 14:50 +0200, Denys Vlasenko wrote: > New-ish versions of gcc allow people to specify optimization > options per function: > > https://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function-Attributes > > optimize > The optimize attribute is used to specify that a function is to be > compiled > with different optimization options than specified on the command line. > Arguments can either be numbers or strings. Numbers are assumed to be an > optimization level. Strings that begin with O are assumed to be an > optimization option, while other options are assumed to be used with > a -f prefix. > > How about not aligning code by default, and using > > #define hot_func > __attribute__((optimize("O2","align-functions=16","align-jumps=16"))) > ... > > void hot_func super_often_called_func(...) {...} > > in hot code paths?
__attribute__((optimize)) is meant for compiler debugging only (to help folks to reduce their testcases to a single function). It should _not_ be used in production code, because the implementation is very buggy. -- Markus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
