Sanjiv Kumar Gupta <[EMAIL PROTECTED]> writes:
> >>I couldn't understand why the insns 620 and 621 are
> >>being generated here as DI moves.
> > I'm not sure specifically why it got a DI move here, but it doesn't
> > look wrong. It's treating the struct named parts as DImode.
> >
> >>This is creating problem since insn 621 gets splitted
> >>after reload into two SI moves,i.e. @(r21, -8) and
> >>@(r21, -4).
> >>This renders insns 619 as dead and hence insns 618 and
> >>insn 429 as dead, which are eliminated by flow2.
> > It does look rather suspicious, but it's hard to know whether it is
> > wrong without seeing the value in r1.
> >
> r1 looks unrelated to struct members, and is being used by the
> ifcvt pass to expand some comparison insns.
In your .23 file, this is insn 431:
(insn 431 430 432 39 0x1002f420 (set (subreg:SI (reg/v:DI 153) 0)
(reg/v:SI 77)) 6 {*movsi} (insn_list 429 (nil))
(expr_list:REG_DEAD (reg/v:SI 77)
(nil)))
So it is setting the first SI subreg of a DI value. reload decides to
do an output reload for register 153. Since register 153 is DImode,
it does a DImode reload.
It winds up copying the DImode value to r2, and then writing r2 to
memory. The double move is because there is a secondary reload
involved. That implies that SECONDARY_OUTPUT_RELOAD_CLASS is defined
and is returning something other than NO_REGS for this case.
I see that insn 429 is setting the high part of register 153. Insn
429 looks like this:
(insn 429 428 430 39 0x1002f420 (set (subreg:SI (reg/v:DI 153) 4)
(plus:SI (reg/v:SI 79)
(reg/v:SI 82))) 12 {addsi3} (insn_list 422 (nil))
(expr_list:REG_DEAD (reg/v:SI 82)
(expr_list:REG_DEAD (reg/v:SI 79)
(nil))))
But note that a set to a subreg is explicitly defined to set the other
parts of the register to garbage. Therefore the value set by insn 429
is destroyed by insn 431.
I would guess that you need a strict_low_part in insns 429 and 431.
See the RTL documentation.
Ian
