[llvm-bugs] [Bug 51761] New: SCEV: loop trip count computation for loops *-or-equal comparisons

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=51761

            Bug ID: 51761
           Summary: SCEV: loop trip count computation for loops *-or-equal
                    comparisons
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: lebedev.ri at gmail.com
                CC: llvm-bugs at lists.llvm.org

The motivation is:
https://godbolt.org/z/dYeWcvz6T
We fail to compute the trip count, and fail to vectorize.
Let's ignore the lowering of the OpenMP for a second (it may be suboptimal.)

Indeed, support for ULE/UGE is missing in
ScalarEvolution::computeExitLimitFromICmp()

I think the formula is:
https://godbolt.org/z/q61j4cf5K https://alive2.llvm.org/ce/z/htSXXe

Now, ignorant question: i'm guessing this is much more complicated
than just asking `ScalarEvolution::howManyLessThans()`
and incrementing the result?

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