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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/98597] [11 Regression] ICE in print_mem_ref
 since r11-6508-gabb1b6058c09a7c0
Date: Tue, 12 Jan 2021 18:39:38 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98597

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

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

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The bug is clear:
  const bool addr =3D TREE_CODE (arg) =3D=3D ADDR_EXPR;
  if (addr)
    {
      arg =3D TREE_OPERAND (arg, 0);
...
    }
makes arg sometimes pointer and sometimes what the pointer points to (which=
 can
be another pointer or something completely different).
So obviously
  tree arg_type =3D TREE_TYPE (TREE_TYPE (arg));
can't work reliably.
Either the arg =3D TREE_OPERAND (arg, 0); should be done only if byte_off =
=3D=3D 0,
or everything else that uses TREE_TYPE (TREE_TYPE (arg)) needs to be change=
d to
do something different based on whether addr is true or false.
I'd note that having the same variable represent different levels of
indirection in the same code depending on some circumstances is a maintaina=
nce
nightmare.
E.g. instead of having a bool whether arg was originally ADDR_EXPR or not, =
it
might be better to keep arg as it is and have another tree that would repre=
sent
what arg points to if it is ADDR_EXPR, otherwise NULL_TREE.=