[Bug optimization/12630] [3.4 regression] Various unrecognizable insns and ICEs at -O3

[dave at hiauly1 dot hia dot nrc dot ca]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12630



------- Additional Comments From dave at hiauly1 dot hia dot nrc dot ca  2003-10-16 20:46 -------
Subject: Re:  [3.4 regression] Various unrecognizable

> > (insn 6 4 7 0 ../../gcc/gcc/varasm.c:1902 (parallel [
> >             (set (mem/s:BLK (reg/f:SI 95) [102 d+0 S24 A32])
> > 		(mem/s:BLK (reg/v/f:SI 94 [ d ]) [102 d+0 S24 A32]))
> > 	    (clobber (reg/f:SI 95))
> > 	    (clobber (reg/f:SI 96 [ d ]))
> > 	    (clobber (reg:SI 97))
> > 	    (clobber (reg:SI 98))
> > 	    (clobber (reg:SI 99))
> > 	    (use (const_int 24 [0x18]))
> > 	    (use (const_int 4 [0x4]))
> > 	]) 72 {movstrsi_internal} (nil)
> >     (nil))
> > 
> > Insn 5 has been deleted.
> > 
> > I don't see any way to have an insn with an operand that's both an input
> > and clobbered.
> 
> This is not problem - you simply load the value into input operant and
> then don't expect it to stay there after the instruction.
> The transfromation above looks valid to me.  Reload ought to be able to
> manage the set operand match clobbers.

Possibly reload would fix this up but we didn't get that far.  The problem
as I see it is that there is no indication that SI 94 is clobbered and
has to die.  I think this is why there is an inconsistency in the death
notes and the ICE.  If SI 94 were used after this instruction, the
transformation wouldn't be valid.

Dave