On 1/13/16 06:21, Al Viro wrote: > On Wed, Jan 13, 2016 at 05:42:20AM +0800, Chen Gang wrote: > >> For me, it really generates a little better code: >> >> - Both 1-word store and 1-byte store are 1 instruction, normally, they >> have the same execution speed (although it is not quite precise). >> >> - But 1-byte store instruction has short length under CISC archs, which >> can generate a little better code globally. >> >> - For most of archs, 1-word store can process bytes nonalignment cases, >> for check_mount() individually, the parameter data may be not word >> alignment, which may cause the 1-word store slower than 1-byte store. > > What the hell do you mean, unaligned? It's given an address of local > variable of type int; it _will_ be aligned, or the compiler is FUBAR. > I guess you misunderstand my meaning, in our case, it should not happen, so I say "for check_mount() individually". For 32 bits store instruction, we need consider about the byte alignment. > As for the inlines... frankly, if gcc generates a different code from having > replaced int with bool in those, it's time to do something very nasty to > gcc developers. > Could you provide the related proof? Thanks. -- Chen Gang (陈刚) Open, share, and attitude like air, water, and life which God blessed -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
