[llvm] [VPlan] Move predication to VPlanTransform (NFC). (PR #128420)

[via llvm-commits]

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@@ -9542,26 +9314,24 @@ LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(VFRange &Range,
       } else {
         Builder.insert(Recipe);
       }
-      if (Recipe->getNumDefinedValues() == 1)
+      if (Recipe->getNumDefinedValues() == 1) {
         SingleDef->replaceAllUsesWith(Recipe->getVPSingleValue());
-      else
+        Old2New[SingleDef] = Recipe->getVPSingleValue();
+      } else {
         assert(Recipe->getNumDefinedValues() == 0 &&
                "Unexpected multidef recipe");
-      R.eraseFromParent();
+        R.eraseFromParent();
+      }
     }
   }
 
-  VPBlockBase *PrevVPBB = nullptr;
-  for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(RPOT)) {
-    // Flatten the CFG in the loop. Masks for blocks have already been generated
-    // and added to recipes as needed. To do so, first disconnect VPBB from its
-    // successors. Then connect VPBB to the previously visited VPBB.
-    for (auto *Succ : to_vector(VPBB->getSuccessors()))
-      VPBlockUtils::disconnectBlocks(VPBB, Succ);
-    if (PrevVPBB)
-      VPBlockUtils::connectBlocks(PrevVPBB, VPBB);
-    PrevVPBB = VPBB;
-  }
+  // replaceAllUsesWith above may invalidate the block masks. Update them here.
+  // TODO: Include the masks as operands in the predicated VPlan directly
+  // to remove the need to keep a map of masks beyond the predication
+  // transform.
+  RecipeBuilder.updateBlockMaskCache(Old2New);
+  for (const auto &[Old, New] : Old2New)
----------------
ayalz wrote:

```suggestion
  for (const auto &[Old, _] : Old2New)
```
?

https://github.com/llvm/llvm-project/pull/128420