cant_combine_insn_p hard_reg->reg moves

[Richard Henderson]

On Tue, Dec 25, 2001 at 09:02:42PM -0500, David Edelsohn wrote:
> Could cant_combine_insn_p test for hard regs with either REG_EQUIV
> involving computations of ARG_POINTER_REGNUM or FUNCTION_VALUE_REGNO_P?

No.  IIRC, this was introduced specifically to cure problems with
argument registers.  x86 regparm is the biggest offender here.

The only solutions are a new register allocator, or post-reload
cleanup optimizations such as -fcprop-registers.  Anything else
risks keeping a hard register live too long.


r~