parts of drreg are not well ported to AArch64: 32-bit write clears 64-bit; avoid SP
Noticed a couple of things in drreg that are not well ported to AArch64:
GPR liveness: the IF_X86_64
for 32-bit reg write zeroing top 32 should be IF_X64 to cover AArch64 too.
s/IF_NOT_ARM/IF_NOT_AARCHXX/
here:
* On AArch64 use of SP is very restricted.
*/
IF_NOT_ARM(|| reg == DR_REG_XSP))