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RE: Live range splitting in new allocator
- To: "Joe Buck" <jbuck at racerx dot synopsys dot com>, "Gcc at Gcc dot Gnu. Org" <gcc at gcc dot gnu dot org>
- Subject: RE: Live range splitting in new allocator
- From: "Rob Taylor" <robt at flyingpig dot com>
- Date: Thu, 1 Feb 2001 09:32:12 -0000
> Joe Buck wrote:
> On Wed, Jan 31, 2001 at 05:11:16PM +0100, Christian Iseli wrote:
> > > For the registers, I guess the function prologue could set them to
> > > the specified value at the same time as the stack...
>
> Michael Meissner writes:
> > That assumes there is a convenient method to set the call clobbered
> registers
> > (and call saved registers that are used) to a given value. Some
> registers are
> > harder to set (for example fp registers on machines where you can't
> copy from
> > int registers to fp registers without going through memory).
>
> You're attacking the problem at too low a level. Front ends can insert
> initializations for all automatic variables easily enough. This then
> allows dead code elimination to kill unused initializations.
>
Indeed, it'd have to go in the front-end - It wouldn't make any sense for (say)
a language that is defined to initialise all variables...
Rob Taylor