https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101865
--- Comment #6 from HaoChen Gui <guihaoc at gcc dot gnu.org> --- (In reply to Segher Boessenkool from comment #5) > (In reply to HaoChen Gui from comment #4) > > I wonder if it's a Power8 architecture when those 6 options are all > > disabled. Or it is regressed to Power7? The "_ARCH_PWR8" represents the > > hardware architecture or the ISA it can be taken? > > It says what version of the ISA is effective. It should correspond to the > -mcpu= used. > > Even if it would be possible to use -mcpu=power8 and then other command line > flags that set everything back to it being just like Power7 (architecturally > that is, ignoring scheduling etc.), we should still define _ARCH_PWR8. Thanks for your comments. If it's architecturally Power7, why we still need to define _ARCH_PWR8. Does _ARCH_PWR8 impact anything during the compiling? Could we just use mcpu instead? Seems _ARCH_PWR8 only affects instruction selection right now.
