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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/113622] [11/12/13/14 Regression] ICE with
 vectors in named registers
Date: Mon, 29 Jan 2024 09:27:35 +0000
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X-Bugzilla-Keywords: ice-on-valid-code, testsuite-fail
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113622

--- Comment #15 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #11)
> I think it is most important we don't ICE and generate correct code.  I
> doubt this is used too much in real-world code, otherwise it would have b=
een
> reported years ago, so how efficient it will be is less important.

We do spill on the read side already.  On the write side the ICE is because
of r0-71337-g1e188d1e130034.  Note we're spilling parts of bitpos to offset:

  /* Otherwise, split it up.  */
  if (offset)
    {
      /* Avoid returning a negative bitpos as this may wreak havoc later.  =
*/
      if (!bit_offset.to_shwi (pbitpos) || maybe_lt (*pbitpos, 0))
        {
          *pbitpos =3D num_trailing_bits (bit_offset.force_shwi ());
          poly_offset_int bytes =3D bits_to_bytes_round_down (bit_offset);
          offset =3D size_binop (PLUS_EXPR, offset,
                               build_int_cst (sizetype, bytes.force_shwi ()=
));
        }

      *poffset =3D offset;

but it can also be large positive when the bit amount doesn't fit a HWI.

The flow of 'to' expansion is a bit awkward, but the following properly
spills in case of variable offset and non-MEM_P:

diff --git a/gcc/expr.cc b/gcc/expr.cc
index ee822c11dce..f54d0b1474e 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -6061,6 +6061,7 @@ expand_assignment (tree to, tree from, bool nontempor=
al)
            to_rtx =3D adjust_address (to_rtx, BLKmode, 0);
        }

+      rtx stemp =3D NULL_RTX, old_to_rtx =3D NULL_RTX;
       if (offset !=3D 0)
        {
          machine_mode address_mode;
@@ -6070,9 +6071,24 @@ expand_assignment (tree to, tree from, bool nontempo=
ral)
            {
              /* We can get constant negative offsets into arrays with brok=
en
                 user code.  Translate this to a trap instead of ICEing.  */
-             gcc_assert (TREE_CODE (offset) =3D=3D INTEGER_CST);
-             expand_builtin_trap ();
-             to_rtx =3D gen_rtx_MEM (BLKmode, const0_rtx);
+             if (TREE_CODE (offset) =3D=3D INTEGER_CST)
+               {
+                 expand_builtin_trap ();
+                 to_rtx =3D gen_rtx_MEM (BLKmode, const0_rtx);
+               }
+             /* Else spill for variable offset to the destination.  */
+             else
+               {
+                 gcc_assert (!TREE_CODE (from) =3D=3D CALL_EXPR
+                             && COMPLETE_TYPE_P (TREE_TYPE (from))
+                             && (TREE_CODE (TYPE_SIZE (TREE_TYPE (from)))
+                                 !=3D INTEGER_CST));
+                 stemp =3D assign_stack_temp (GET_MODE (to_rtx),
+                                            GET_MODE_SIZE (GET_MODE
(to_rtx)));
+                 emit_move_insn (stemp, to_rtx);
+                 old_to_rtx =3D to_rtx;
+                 to_rtx =3D stemp;
+               }
            }

          offset_rtx =3D expand_expr (offset, NULL_RTX, VOIDmode, EXPAND_SU=
M);
@@ -6305,6 +6321,9 @@ expand_assignment (tree to, tree from, bool nontempor=
al)
                                  bitregion_start, bitregion_end,
                                  mode1, from, get_alias_set (to),
                                  nontemporal, reversep);
+         /* Move the temporary storage back to the non-MEM_P.  */
+         if (stemp)
+           emit_move_insn (old_to_rtx, stemp);
        }

       if (result)=