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Date: Thu, 07 Apr 2011 14:05:00 -0000
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Subject: Re: PATCH: PR middle-end/48440: [4.7 Regression] FAIL: gcc.c-torture/compile/labels-3.c
From: "H.J. Lu" <hjl.tools@gmail.com>
To: Michael Matz <matz@suse.de>
Cc: Richard Guenther <richard.guenther@gmail.com>, Paolo Bonzini <bonzini@gnu.org>, gcc-patches@gcc.gnu.org
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On Thu, Apr 7, 2011 at 5:34 AM, Michael Matz <matz@suse.de> wrote:
> Hi,
>
> On Thu, 7 Apr 2011, Richard Guenther wrote:
>
>> > 5600 =A0 =A0 =A0newx =3D simplify_subreg (outermode, op, innermode, by=
te);
>> > (gdb) f 1
>> > #1 =A00x0000000000708494 in expand_expr_real_2 (ops=3D0x7fffffffb0c0, =
target=3D0x0,
>> > =A0 =A0tmode=3DVOIDmode, modifier=3DEXPAND_INITIALIZER)
>> > =A0 =A0at /export/gnu/import/git/gcc-x32/gcc/expr.c:7366
>> > 7366 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0op0 =3D simplify_gen_subreg (mode,=
 op0, inner_mode,
>> > (gdb) call debug_tree (treeop0)
>> > =A0<addr_expr 0x7ffff0a78d50
>> > =A0 =A0type <pointer_type 0x7ffff0b83f18
>> > =A0 =A0 =A0 =A0type <void_type 0x7ffff0b83e70 void VOID
>> > =A0 =A0 =A0 =A0 =A0 =A0align 8 symtab 0 alias set -1 canonical type 0x=
7ffff0b83e70
>> > =A0 =A0 =A0 =A0 =A0 =A0pointer_to_this <pointer_type 0x7ffff0b83f18>>
>> > =A0 =A0 =A0 =A0sizes-gimplified public unsigned SI
>> > =A0 =A0arg 0 <label_decl 0x7ffff0b7b400 l2 type <void_type 0x7ffff0b83=
e70 void>
>> > (gdb) call debug_rtx (op0)
>> > (label_ref/v:DI 22)
>> > (gdb)
>> >
>>
>> First I wonder what CONSTANT_P object we arrive with here (it looks like
>> something unfolded, given that we likely came here with a NOP_EXPR).
>
> The CONSTANT_P object is the '(label_ref/v:DI 22)'. =A0Not only CONST_INT
> are CONSTANT_P, also some others (symbol_ref too). =A0Those might have a
> mode. =A0Here the label_ref has DImode, but the pointer type in trees poi=
nts
> to an SImode. =A0The latter makes sense, because that's what ptr_mode is =
for
> HJs target.
>
> HJ: you'll need to tell us what you mean with 'breaks
> gcc.c-torture/compile/labels-3.c' . =A0What breaks, in which way?
>

I got

#0  fancy_abort (
    file=3D0x12470e0 "/export/gnu/import/git/gcc-x32/gcc/simplify-rtx.c",
    line=3D5266, function=3D0x1248470 "simplify_subreg")
    at /export/gnu/import/git/gcc-x32/gcc/diagnostic.c:893
#1  0x00000000009d0ab5 in simplify_subreg (outermode=3DHImode, op=3D0x7ffff=
0c55dd0,
    innermode=3DSImode, byte=3D0)
    at /export/gnu/import/git/gcc-x32/gcc/simplify-rtx.c:5265
#2  0x00000000009d1e83 in simplify_gen_subreg (outermode=3DHImode,
    op=3D0x7ffff0c55dd0, innermode=3DSImode, byte=3D0)
    at /export/gnu/import/git/gcc-x32/gcc/simplify-rtx.c:5600
#3  0x0000000000708736 in expand_expr_real_2 (ops=3D0x7fffffffb480, target=
=3D0x0,
    tmode=3DVOIDmode, modifier=3DEXPAND_INITIALIZER)
    at /export/gnu/import/git/gcc-x32/gcc/expr.c:7366
#4  0x00000000007153e1 in expand_expr_real_1 (exp=3D0x7ffff0a87f30, target=
=3D0x0,
    tmode=3DVOIDmode, modifier=3DEXPAND_INITIALIZER, alt_rtl=3D0x0)
    at /export/gnu/import/git/gcc-x32/gcc/expr.c:9728
..
(gdb) f 3
#3  0x0000000000708736 in expand_expr_real_2 (ops=3D0x7fffffffb480, target=
=3D0x0,
    tmode=3DVOIDmode, modifier=3DEXPAND_INITIALIZER)
    at /export/gnu/import/git/gcc-x32/gcc/expr.c:7366
7366		    op0 =3D simplify_gen_subreg (mode, op0, inner_mode,
(gdb) call debug_rtx (op0)
(label_ref/v:DI 22)
(gdb) p  inner_mode
$2 =3D SImode
(gdb)

We are calling simplify_gen_subreg with wrong inner_mode.

--=20
H.J.