This commit makes two changes:
- Remove the push and pop instructions that were saving and restoring %ebx
before and after cpuid in 32-bit pic mode. We were doing this to ensure we
don't lose the GOT address in pic register %ebx, but this isn't necessary
because the GOT address is kept in a virtual register.
- In 64-bit mode, preserve base register %rbx around cpuid.
This fixes PR20311 and rdar://problem/17686779.
llvm-svn: 218173
Akira Hatanaka