[Codegen] Revert rL354676/rL354677 and followups - introduced PR43446 miscompile

This reverts https://reviews.llvm.org/D58468
(rL354676, 44037d7a),
and all and any follow-ups to that code block.

https://bugs.llvm.org/show_bug.cgi?id=43446

(cherry picked from commit d20907d1)