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Re: m68k bootstrap problem
Hi,
On Wed, 20 Jun 2007, Kenneth Zadeck wrote:
> If we add the dead note there we are asserting that the value is
> modified by the caller. however it might not be and someone could write
> a piece of asm right after the call to use that reg if the person knew
> that the reg was not modified by that particular call.
I have big problems to see this as a valid example, this sounds just
broken. First off the user had to know the register was alive before and
then the user had to magically know the register isn't clobbered by the
call (e.g. loading the address of the function into that register).
You could declare the variable as asm register variable, then it might
work, but then the register wouldn't be available for allocation anyway
and the whole problem changes.
> having the dead note there is asserting to the register allocator that
> they are free to use that reg after the calll in any way that it wants
> and there is a (small) possibility that is wrong.
IMO there is nothing wrong with this.
bye, Roman