Florian Hahn f75564ad4e Reland "[SCEVExpander] Add option to preserve LCSSA directly."
This reverts the revert commit dc2867576886247cbe351e7c63618c09ab6af808.

It includes a fix for Polly, which uses SCEVExpander on IR that is not
in LCSSA form. Set PreserveLCSSA = false in that case, to ensure we do
not introduce LCSSA phis where there were none before.
2020-07-29 20:41:53 +01:00
..