[llvm] [VPlan] Try to hoist Previous (and operands), if sinking fails for FORs. (PR #108945)

[Florian Hahn via llvm-commits]

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@@ -147,14 +147,57 @@ exit:
 }
 
 ; This test has two FORs (for.x and for.y) where incoming value from the previous
-; iteration (for.x.prev) of one FOR (for.y) depends on another FOR (for.x). Due to
-; this dependency all uses of the former FOR (for.y) should be sunk after
-; incoming value from the previous iteration (for.x.prev) of te latter FOR (for.y).
-; That means side-effecting user (store i64 %for.y.i64, ptr %gep) of the latter
-; FOR (for.y) should be moved which is not currently supported.
+; iteration (for.x.prev) of one FOR (for.y) depends on another FOR (for.x).
+; Sinking would require moving a recipe with side effects (store). Instead,
+; for.x.prev can be hoisted.
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fhahn wrote:

Ah yes, should be for.x.next. updated, thanks!

https://github.com/llvm/llvm-project/pull/108945