Re: Your recent reload changes

[Richard Henderson <rth at cygnus dot com>]

On Tue, Aug 22, 2000 at 11:01:07AM -0700, Richard Henderson wrote:
> On Tue, Aug 22, 2000 at 09:45:01AM -0600, Jeffrey A Law wrote:
> > However, after your patch we get the following reloads:
> > 
> > Reload 0: R1_REGS, RELOAD_FOR_INPUT (opnum = 0), can't combine, 
> > secondary_reload_p
> > Reload 1: reload_in (SI) = (high:SI (symbol_ref:SI ("warn_std_ptr")))
> >         GENERAL_REGS, RELOAD_FOR_OUTPUT_ADDRESS (opnum = 0), can't combine
> 
> This is the problem.  The secondary reload should have the same
> lifetime as its primary, but doesn't.  I'll see about fixing this.

Bother.  Even after fixing this it still doesn't work.  We've got

Reload 0: R1_REGS, RELOAD_FOR_OPERAND_ADDRESS (opnum = 0),
	can't combine, secondary_reload_p
Reload 1: reload_in (SI) = (high:SI (symbol_ref:SI ("warn_std_ptr")))
        GENERAL_REGS, RELOAD_FOR_OPERAND_ADDRESS (opnum = 0), can't combine
        reload_in_reg: (reg:SI 466)
        secondary_in_reload = 0
        secondary_in_icode = reload_insi
Reload 2: reload_out (SI) = (mem/f:SI (lo_sum:SI (reg:SI 466)
                                (symbol_ref:SI ("warn_std_ptr"))) 110)
        NO_REGS, RELOAD_FOR_OUTPUT (opnum = 0), optional
        reload_out_reg: (mem/f:SI (lo_sum:SI (reg:SI 466)
                            (symbol_ref:SI ("warn_std_ptr"))) 110)
Reload 3: R1_REGS, RELOAD_FOR_INPUT (opnum = 1),
	can't combine, secondary_reload_p
Reload 4: reload_in (SI) = (symbol_ref:SI ("warn_std"))
        GENERAL_REGS, RELOAD_FOR_INPUT (opnum = 1), can't combine
        reload_in_reg: (reg:SI 467)
        secondary_in_reload = 3
        secondary_in_icode = reload_insi

I'm not quite sure the distinction between OPERAND_ADDRESS and INPUT,
as they're both inputs, of a sort.  But what it means is that we've
still got overlapping lifetimes for the R1 secondary reloads.

The Problem here is that we've gone from one extreme to another.  From
no overlapping lifetimes between the secondary and primary to completely
overlapping lifetimes.  But that's just as inaccurate.  What we need is
for secondary reloads (with reload_in/out) to be live until the end of
the reload insn.  When using something like INPUT_ADDRESS they're
considered live until the beginning of the reload insn.

So, whaddaya wanna do?  Revert the whole thing and find some other
workaround for ia64 (OImode reloads?  Eek.), add yet another lifetime,
or see how much work finishing Bernd's reload dependancy bit would take?


r~