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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/104970] [12 Regression] ICE in execute_todo,
 at passes.cc:2133 since r12-6480-gea19c8f33a3a8d2b
Date: Mon, 21 Mar 2022 11:59:27 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104970

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Not a SSA_NAME, but no longer existing temporary.
If a type has non-constant extents or bit or byte size, the vars (or SSA_NA=
MEs)
used in those sizes are valid just during gimplification, they can't be
recovered later on when they could have been DCEd or changed in some other =
way.
For automatic VLAs the only thing that can be done is look up the correspon=
ding
__builtin_alloca_with_align and use its size argument as the size of the wh=
ole
object, for VLA parameters it just doesn't exist.
The gimple dump here has:
__attribute__((access ("^1[$ ],$0", )))
void mleye (int l, double[0:D.1990] * E)
{
  int l.0;
  sizetype D.1990;
  bitsizetype D.1991;
  sizetype D.1992;

  l.0 =3D l;
  _1 =3D (long int) l.0;
  _2 =3D _1 + -1;
  _3 =3D (sizetype) _2;
  D.1990 =3D _3;
  _4 =3D (sizetype) l.0;
  _5 =3D (bitsizetype) _4;
  _6 =3D _5 * 64;
  D.1991 =3D _6;
  _7 =3D (sizetype) l.0;
  _8 =3D _7 * 8;
  D.1992 =3D _8;
  memset2 (E, 0, 8);
}
so D.1990 is the TYPE_MAX_VALUE (TYPE_DOMAIN (type)) i.e. l - 1,
D.1991 is TYPE_SIZE (type) (l * 64, i.e. bit size) and D.1992 is TYPE_SIZE_=
UNIT
(type) (l * 8, i.e. byte size).
The ssa pass turns all those into SSA_NAMEs though (and nothing updates the
TYPE* values) and dse1 removes all those unused stmts.
The objsz1 emergency dump shows though:
  _4 =3D (sizetype) l_1(D);
  _6 =3D D.1992 * _4;
  _5 =3D _6;
  __builtin___memset_chk (E_3(D), 0, 8, _5);
so it strangely wants to multiply D.1992 (which can't be used but as sizeof
(*E)) with l argument, so that is l * l * sizeof (double) if D.1992 could be
used.=