Rosie Sumpter f117ed542f [LoopFlatten] Fix missed LoopFlatten opportunity ...

When the limit of the inner loop is a known integer, the InstCombine
pass now causes the transformation e.g. imcp ult i32 %inc, tripcount ->
icmp ult %j, tripcount-step (where %j is the inner loop induction
variable and %inc is add %j, step), which is now accounted for when
identifying the trip count of the loop. This is also an acceptable use
of %j (provided the step is 1) so is ignored as long as the compare
that it's used in is also the condition of the inner branch.

Differential Revision: https://reviews.llvm.org/D105802

2021-08-02 11:09:54 +01:00

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