[LLVMdev] global register allocation.

[Sanjiv Gupta]

Thanks again. One more question here:
Since the regalloc works once per function, do I stil have access to
the Call graph?
Just saving information between regalloc passes for different
functions may not be enough for my case. I will need to maintain the
regalloc info of various passes in the call graph order.
Anyways thanks for your inputs. I will get back if I need to learn more.

Sanjiv

On Nov 23, 2007 11:29 PM, Fernando Magno Quintao Pereira
<fernando at cs.ucla.edu> wrote:
>
> Hi, again,
>
>     I think you can do it in the same way that the other allocators have
> been coded, i.e extend RA, register the pass and so forth. I am not sure
> about the best way to pass information among a run of RegAlloc to the
> other, maybe the other guys in the list could suggest something. Yet, you
> can always dump it into a file, and read it again, everytime it is
> necessary. Remember that RegAlloc will be called once per function. Also,
> LLVM does very aggressive inlining of method calls, and this may cause the
> benefits of interprocedural register allocation to be very small, if any.
> There was one guy (google for Philip Brisk) who was working with
> interprocedural RA on SSA-form programs.
>
> best,
>
> Fernando
>
>
> > On 11/23/07, Fernando Magno Quintao Pereira <fernando at cs.ucla.edu> wrote:
> >>
> >>
> >> Hi, Sanjiv,
> >>
> >>     those passes operate on the whole machine function. Each machine
> >> function contains many basic blocks. If a program has many functions, the
> >> register allocator will be called as many times, i.e it does not do
> >> interprocedural allocation.
> >>
> >> best,
> >>
> >> Fernando
> >
> >
> > Thanks for replying back.
> > I am looking to write a regalloc pass that does interprocedural regalloc.
> > By constructing a Call Graph and keeping the registers in a single call
> > chain different so that i can avoid spilling (saving) across function calls.
> > What will be the right place to do so?
> >
> > Sanjiv
> >
> >> As far as I understand , the regalloc passes provided operate on basic
> >> block
> >>> level?
> >>> Is there anything that operate on the whole Module?
> >>>
> >>> Thx,
> >>> Sanjiv
> >>>
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