[PATCH] D109428: [SImplifyCFG] SwitchInst processing redirecting the UB edges from the BB with the phiNode, that contains the UB, to the new BB.

[Dmitry Bakunevich via Phabricator via llvm-commits]

dbakunevich updated this revision to Diff 371304.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D109428/new/

https://reviews.llvm.org/D109428

Files:
  llvm/lib/Transforms/Utils/SimplifyCFG.cpp


Index: llvm/lib/Transforms/Utils/SimplifyCFG.cpp
===================================================================
--- llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -6613,10 +6613,25 @@
           if (DTU)
             DTU->applyUpdates({{DominatorTree::Delete, Predecessor, BB}});
           return true;
+        } else if (SwitchInst *SI = dyn_cast<SwitchInst>(T)) {
+          // Create the new block in which will redirect the edges that 
+          // lead to undefine behavior
+          BasicBlock *Unreachable = BasicBlock::Create(
+              Predecessor->getContext(), "unreachable", SI->getFunction());
+          Builder.SetInsertPoint(Unreachable);
+          // The new block contains only one instruction: Unreachable
+          Builder.CreateUnreachable();
+          for (auto &Case : SI->cases())
+            if (Case.getCaseSuccessor() == BB)
+              Case.setSuccessor(Unreachable);
+
+          if (DTU)
+            DTU->applyUpdates(
+                { { DominatorTree::Delete, Predecessor, BB },
+                  { DominatorTree::Insert, Predecessor, Unreachable } });
+          return true;
         }
-        // TODO: SwitchInst.
       }
-
   return false;
 }
 


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