https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106680
--- Comment #10 from Sebastian Huber <sebastian.hu...@embedded-brains.de> --- (In reply to Kewen Lin from comment #9) > Note that now we only disable implicit powerpc64 for -m32 when the > OS_MISSING_POWERPC64 is set. > > /* Don't expect powerpc64 enabled on those OSes with OS_MISSING_POWERPC64, > since they do not save and restore the high half of the GPRs correctly > in all cases. If the user explicitly specifies it, we won't interfere > with the user's specification. */ > #ifdef OS_MISSING_POWERPC64 > if (OS_MISSING_POWERPC64 > && TARGET_32BIT > && TARGET_POWERPC64 > && !(rs6000_isa_flags_explicit & OPTION_MASK_POWERPC64)) > rs6000_isa_flags &= ~OPTION_MASK_POWERPC64; > #endif > > But rtems.h doesn't define OS_MISSING_POWERPC64 RTEMS supports the 64-bit PowerPC for the 64-bit multilibs. > > gcc/config/rs6000/linux.h:#define OS_MISSING_POWERPC64 1 > gcc/config/rs6000/freebsd64.h:#define OS_MISSING_POWERPC64 !TARGET_64BIT > gcc/config/rs6000/aix.h:#define OS_MISSING_POWERPC64 1 > gcc/config/rs6000/linux64.h:#define OS_MISSING_POWERPC64 !TARGET_64BIT > > meanwhile cpu "e6500" has MASK_POWERPC64 set by default (it's 64bit core). > > That's why you still have powerpc64 flag set when you specify -m32 on rtems. For some applications, you don't need the 64-bit support on the e6500 machines. So, we have 32-bit and 64-bit multilibs. This is just a performance optimization for some applications.
