[llvm] [LV] Transform to handle exits in the scalar loop (PR #148626)

[Gaëtan Bossu via llvm-commits]

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@@ -8202,6 +8205,8 @@ void LoopVectorizationPlanner::buildVPlansWithVPRecipes(ElementCount MinVF,
   auto VPlan0 = VPlanTransforms::buildVPlan0(
       OrigLoop, *LI, Legal->getWidestInductionType(),
       getDebugLocFromInstOrOperands(Legal->getPrimaryInduction()), PSE);
+  VPlan0->setEarlyExitContinuesInScalarLoop(Legal->hasUncountableEarlyExit() &&
+                                            HandleEarlyExitsInScalarTail);
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gbossu wrote:

I think setters should be avoided because they allow multiple points of (re)definition, which makes the data flow harder to follow.

Adding a `EarlyExitContinuesInScalarLoop` parameter to the plan's constructor makes it obvious we now have an additional lever to control the vectorisation strategy.

https://github.com/llvm/llvm-project/pull/148626