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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug middle-end/67442] [5/6 Regression] GCC 5.2.0 on x86_64 creates invalid address on specific array index calculation through pointer
Date: Thu, 03 Sep 2015 08:59:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67442

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
That is,

tree
wide_int_to_tree (tree type, const wide_int_ref &pcst)
{
...
  unsigned int prec = TYPE_PRECISION (type);
  signop sgn = TYPE_SIGN (type);
...
  wide_int cst = wide_int::from (pcst, prec, sgn);

is according to its docs "The value is extended from its precision according to
the sign of the type", but that isn't what anyone would expect.  IIRC
the wide_int_ref doesn't have a "sign", so we can't do the correct thing.

So IMHO we should require pcst.get_precision () == prec and maybe offer an
overload

tree
wide_int_to_tree (tree type, const wide_int_ref &pcst, signop sgn);

that can specify the sign of pcst (or maybe require that always...).