[PATCH] D155478: [NewGVN] Abort PHIOfOps if found singleton PHI

[Manuel Brito via Phabricator via llvm-commits]

ManuelJBrito created this revision.
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Currently we just bypass singleton phis, however we know that in order to create the phi of ops all phis must be in the same block. Therefore if one phi is a singleton then the rest are as well.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D155478

Files:
  llvm/lib/Transforms/Scalar/NewGVN.cpp


Index: llvm/lib/Transforms/Scalar/NewGVN.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/NewGVN.cpp
+++ llvm/lib/Transforms/Scalar/NewGVN.cpp
@@ -2749,10 +2749,10 @@
       return nullptr;
     }
     // No point in doing this for one-operand phis.
-    if (OpPHI->getNumOperands() == 1) {
-      OpPHI = nullptr;
-      continue;
-    }
+    // Since all PHIs for operands must be in the same block, then they must
+    // have the same number of operands so we can just abort.
+    if (OpPHI->getNumOperands() == 1)
+      return nullptr;
   }
 
   if (!OpPHI)


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