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From: "amacleod at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/97381] [11 Regression] ice error: invalid
 types in nop conversion
Date: Wed, 14 Oct 2020 15:47:11 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D97381

--- Comment #8 from Andrew Macleod <amacleod at redhat dot com> ---
in particular:

  _2 =3D (int) c_8;
  _3 =3D _2 * 148372120;
  _4 =3D a.0_1 / _3;
  if (_4 !=3D 0)


we do not wind back thru divides at the moment (unless they are exact divid=
es)
so when processing the false edge to calculate a range for c_8 (which feeds
into a phi eventually)

so when processing=20
  [0, 0] =3D a.0_1 / _3

and trying to calculate a range for _3 , range-ops was returning false,
indicating no further processing should be done (so we wont know anything e=
lse
about c_8)

By ignoring that, and continuing to process
  _3 =3D _2 * 148372120;
with a LHS that was garbage, we were getting some less than ideal results a=
s we
continued back to the cast and figured a value for c_8.=