Re: [PATCH V2] Extend 16/32-bit vector bit_op patterns with (m, 0, i) alternative.

[Uros Bizjak <ubizjak@gmail.com>]

On Tue, Jul 19, 2022 at 8:56 AM Hongtao Liu <crazylht@gmail.com> wrote:
>
> On Tue, Jul 19, 2022 at 2:35 PM Uros Bizjak via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > On Tue, Jul 19, 2022 at 8:07 AM liuhongt <hongtao.liu@intel.com> wrote:
> > >
> > > And split it after reload.
> > >
> > > > You will need ix86_binary_operator_ok insn constraint here with
> > > > corresponding expander using ix86_fixup_binary_operands_no_copy to
> > > > prepare insn operands.
> > > Split define_expand with just register_operand, and allow
> > > memory/immediate in define_insn, assume combine/forwprop will do optimization.
> >
> > But you will *ease* the job of the above passes if you use
> > ix86_fixup_binary_operands_no_copy in the expander.
> for -m32, it will hit ICE in
> Breakpoint 1, ix86_fixup_binary_operands_no_copy (code=XOR,
> mode=E_V4QImode, operands=0x7fffffffa970) a
> /gcc/config/i386/i386-expand.cc:1184
> 1184      rtx dst = ix86_fixup_binary_operands (code, mode, operands);
> (gdb) n
> 1185      gcc_assert (dst == operands[0]); -- here
> (gdb)
>
> the original operands[0], operands[1], operands[2] are below
> (gdb) p debug_rtx (operands[0])
> (mem/c:V4QI (plus:SI (reg/f:SI 77 virtual-stack-vars)
>         (const_int -8220 [0xffffffffffffdfe4])) [0 MEM <vector(4)
> unsigned char> [(unsigned char *)&tmp2 + 4B]+0 S4 A32])
> $1 = void
> (gdb) p debug_rtx (operands[1])
> (subreg:V4QI (reg:SI 129) 0)
> $2 = void
> (gdb) p debug_rtx (operands[2])
> (subreg:V4QI (reg:SI 98 [ _46 ]) 0)
> $3 = void
> (gdb)
>
> since operands[0] is mem and not equal to operands[1],
> ix86_fixup_binary_operands will create a pseudo register for dst. and
> then hit ICE.
> Is this a bug or assumed?

You will need ix86_expand_binary_operator here.

Uros.