[Bug rtl-optimization/82454] New: Possible future performance regression in x86 for 64-bit constant expansions

["sudi.das at arm dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82454

            Bug ID: 82454
           Summary: Possible future performance regression in x86 for
                    64-bit constant expansions
           Product: gcc
           Version: 7.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sudi.das at arm dot com
  Target Milestone: ---

Created attachment 42317
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42317&action=edit
test1

As per the discussions on 

https://gcc.gnu.org/ml/gcc-patches/2017-04/msg00570.html
https://gcc.gnu.org/ml/gcc-patches/2017-08/msg00039.html
https://gcc.gnu.org/ml/gcc-patches/2017-09/msg01736.html

The patch to add a simplification of 1U << (31 - x) for PR 80131, may lead to a
performance regression for x86.

I am adding the tests that Jakub mentioned as a runtime performance regression
tests.