Re: asm changes? [Was: Re: flow.c bugfix ]

[Richard Henderson <rth at cygnus dot com>]

On Fri, Dec 04, 1998 at 10:48:20PM +0100, Bernd Schmidt wrote:
> If we change gcc to suddenly allocate explicitly clobbered regs to input
> operands, we are going to break all correctly written asm statements
> that assume that this cannot happen.  The correct behaviour has been
> documented at least since gcc-1.42, and actual behaviour has been different
> only on SMALL_REGISTER_CLASSES machines.  I don't think we want to change
> the meaning of all existing asm statements out there.

Uh, we're not suggesting that.  Linus' proposal was to define something
new, an early clobber input:

  asm("" : : "&r"(value))

which would mean that it's register is not shared with any other input
or output, and that its contents are dead after the asm.


r~