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From: "amacleod at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/96542] Failure to optimize simple code to a
 constant when storing part of the operation in a variable
Date: Sat, 17 Jul 2021 02:34:04 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D96542

Andrew Macleod <amacleod at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

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

Range-ops uses wi_fold (implemented by each opcode)  to individually=20
fold subranges one at a time and then combines them. This patch first=20
calls wi_fold_in_parts which checks if one of the subranges is small,=20
and if so, further splits that subrange into constants.

Currently, if a subrange is 4 or less values, then we call it=20
individually for each of the 4 values. 4 was chosen as a reasonable=20
tradeoff between excess work vs benefit.=20=20

this gets all 3 cases now.
fixed=