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From: "amacleod at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/101254] [12 Regression] gcc head does not
 comply fully to -fwrapv since r12-1723
Date: Tue, 29 Jun 2021 17:11:14 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101254

Andrew Macleod <amacleod at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #51083|0                           |1
        is obsolete|                            |

--- Comment #9 from Andrew Macleod <amacleod at redhat dot com> ---
Created attachment 51084
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D51084&action=3Dedit
another patch

OK, fleshed it out.  Your observations about [0,max] for unsigned are true,=
 but
it was harmless.  however, when I broke it into 3 cases, unsigned, wrapping
signed and nornmal signed, it looks like I can simply treat it as wrapping =
and
non-wrapping.. since ~[0,0]for unsigned is the same as [1, max]
anyway I added the LT, LE, and NE cases as well.

I think this is now right and complete?  or have I missed something else..
certainly possible,I'm developing a headache thinking about it.=