[llvm] [LV] Create block in mask up-front if needed. (PR #76635)

[Florian Hahn via llvm-commits]

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@@ -8758,13 +8762,20 @@ LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(VFRange &Range) {
   DFS.perform(LI);
 
   VPBasicBlock *VPBB = HeaderVPBB;
+  bool NeedsMasks = CM.foldTailByMasking() ||
+                    any_of(OrigLoop->blocks(), [this](BasicBlock *BB) {
+                      return Legal->blockNeedsPredication(BB);
+                    });
   for (BasicBlock *BB : make_range(DFS.beginRPO(), DFS.endRPO())) {
     // Relevant instructions from basic block BB will be grouped into VPRecipe
     // ingredients and fill a new VPBasicBlock.
     if (VPBB != HeaderVPBB)
       VPBB->setName(BB->getName());
     Builder.setInsertPoint(VPBB);
 
+    if (VPBB != HeaderVPBB && NeedsMasks)
+      RecipeBuilder.createBlockInMask(BB, *Plan);
+
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fhahn wrote:

Adjusted, thanks!

https://github.com/llvm/llvm-project/pull/76635