const int64_t CFAOffsetFromInitialSP = CallFrameSize;
// Maps of asm register numbers to LLVM register numbers, with 0 indicating
- // an invalid register. We don't use the register classes directly because
- // they specify the allocation order.
+ // an invalid register. In principle we could use 32-bit and 64-bit register
+ // classes directly, provided that we relegated the GPR allocation order
+ // in SystemZRegisterInfo.td to an AltOrder and left the default order
+ // as %r0-%r15. It seems better to provide the same interface for
+ // all classes though.
extern const unsigned GR32Regs[16];
extern const unsigned GR64Regs[16];
extern const unsigned GR128Regs[16];