gcc/resource.c mark_target_live_regs Question

[Brad Lucier]

Re:

> On Thu, Feb 15, 2001 at 09:43:46AM -0800, Mark Mitchell wrote:
> > We're making some assumption that reorg confuses everything, but not
> > across BARRIERs?  Is that it?
> 
> Exactly.
> 
> > mark_target_live_regs mark all registers live if find_basic_block goes
> > back, say, more than 1000 instructions ...
> 
> 50 or 100 is probably a better default.  Remember, that
> if you have N insns in the block you're still going to
> scan N**2/2 insns.
> 
> 
> r~

I'm not exactly understanding all the implications of this discussion,
but one easily gets > 200 instructions in the inner basic block of
a 8-way butterfly FFT code used for bignum multiplication, and I wouldn't
want all registers marked as live in that block.

Brad