Hi! On Sun, Dec 13, 2020 at 03:34:57PM +0100, Piotr Kubaj wrote: > this is only default tuning (-mtune, not -mcpu).
It is both, actually (-mcpu= implies -mtune=) > Linux also does similarly in linux64.h: > 74 #undef PROCESSOR_DEFAULT > 75 #define PROCESSOR_DEFAULT PROCESSOR_POWER7 > 76 #undef PROCESSOR_DEFAULT64 > 77 #define PROCESSOR_DEFAULT64 PROCESSOR_POWER8 Yes, but we still default to power4 on BE Linux (and power8 on LE). I get lost in the macro maze here, not sure how that works :-) > Although there is hard to explain (for me) setting to tune for POWER7 on > 32-bits. POWER7 is 64-bit and it should be more reasonable to optimize for > the last 32-bit machines that still may be in use (so G4). 7450 has very different optimisation than 970. Power7 and 970 have largely similar pipelines. > That said, on the 64-bit front, we will just match the Linux setting. Compile a very simple test and look at the .machine in the generated .s? Does that do what you want? Segher
