[LLVMdev] reg_iterator Caveats

David Greene dag at cray.com
Tue Apr 1 11:27:18 PDT 2008

On Tuesday 01 April 2008 12:35, Chris Lattner wrote:
> On Tue, 1 Apr 2008, David Greene wrote:
> > On Tuesday 01 April 2008 10:47, David Greene wrote:
> >>> reg iterators will return everything that is in the function.  If the
> >>> implicit operands haven't been added to the machieninstrs yet, then
> >>> they won't be returned.
> >>
> >> Hmm...this is definitely NOT true in my copy.  During register
> >> allocation these implicit defs are not returned.  By then the
> >> instructions are most definitely fully constructed.  :)
> >
> > Urk.  It seems things are worse than that, even.
> You should try updating to mainline.  I have no idea what snapshot you
> have.

Yep, it's on my TODO list.

> Barring a serious bug, the use/def chains cannot get out of date.  When a
> machineinstr is inserted into a function or when an operand is added to
> the instr, it is automatically added to the register list.  There is no
> way that these can get out of date, by design.

Ok, I see the code in MachineOperand to do this.  Strange.  I've hacked around
it for the time being.  I'll double-check when we update.


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