[LLVMdev] Recalculating live intervals

[Anton Vayvod]

So what addIntervalsToSpills returns are new intervals to allocate with
infinite weights, right?
And I need not to allocate the old interval. Should hasStackSlot return true
on its register then?


On 8/21/06, Fernando Magno Quintao Pereira <fernando at cs.ucla.edu> wrote:
>
>
> Well, someone correct me if am wrong, but, you still have to allocate
> physical registers to them, because their values must be reloaded before
> been used. But after you spill a register, you break its live ranges, so,
> each use of that register can be loaded into a different physical. In my
> register allocator, after I spill reg_v:
>
> For each use of reg_v:
>    create a new reg_v'
>    replace reg_v by reg_v'
>
> If the instruction containing reg_v' hasn't been scanned by the register
> allocator, when it happens, reg_v' will receive a physical register. You
> must assign to reg_v' a weight such that is is not spilled again,
> otherwise you may enter on an infinite loop, always spilling the same
> spilled register.
>
> Fernando
>
> >
> > So, as far as I understood live intervals with weight equal to HUGE_VAL
> are
> > spilled and I don't need to allocate physical registers for them, right?
> > Shoud hasStackSlot method of VirtRegMap return true for these intervals'
> reg
> > members?
> >
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