[llvm] [VPlan] Model branch cond to enter scalar epilogue in VPlan. (PR #92651)

[via llvm-commits]

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@@ -364,7 +367,8 @@ static bool mergeBlocksIntoPredecessors(VPlan &Plan) {
            vp_depth_first_deep(Plan.getEntry()))) {
     auto *PredVPBB =
         dyn_cast_or_null<VPBasicBlock>(VPBB->getSinglePredecessor());
-    if (PredVPBB && PredVPBB->getNumSuccessors() == 1)
+    if (PredVPBB && PredVPBB->getNumSuccessors() == 1 &&
+        !isa<VPIRBasicBlock>(VPBB))
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ayalz wrote:

Can check above `if (isa<VPIRBasicBlock>(VPBB)) continue;` before setting PredVPBB. Would have been nicer to fold it into blocksOnly<> somehow.

https://github.com/llvm/llvm-project/pull/92651