Kerry McLaughlin f99672568f [LoopVectorize] Fix strict reductions where VF = 1
Currently we will allow loops with a fixed width VF of 1 to vectorize
if the -enable-strict-reductions flag is set. However, the loop vectorizer
will not use ordered reductions if `VF.isScalar()` and the resulting
vectorized loop will be out of order.

This patch removes `VF.isVector()` when checking if ordered reductions
should be used. Also, instead of converting the FAdds to reductions if the
VF = 1, operands of the FAdds are changed such that the order is preserved.

Reviewed By: david-arm

Differential Revision: https://reviews.llvm.org/D104533
2021-06-28 11:27:10 +01:00
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