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

[via llvm-commits]

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@@ -8108,14 +8108,18 @@ void VPRecipeBuilder::createHeaderMask(VPlan &Plan) {
   BlockMaskCache[Header] = BlockMask;
 }
 
-VPValue *VPRecipeBuilder::createBlockInMask(BasicBlock *BB, VPlan &Plan) {
+VPValue *VPRecipeBuilder::getBlockInMask(BasicBlock *BB) {
   assert(OrigLoop->contains(BB) && "Block is not a part of a loop");
 
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ayalz wrote:

nit: can drop the assert that `BB` is part of the loop, suffice to assert it has been cached (which asserts this before caching).
```suggestion
```

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