[PATCH] D54956: [ValueTracking] Look through casts when determining non-nullness

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert created this revision.
jdoerfert added reviewers: fhahn, nlopes, sanjoy, spatel.
Herald added a subscriber: bollu.

Bitcast, address space cast and ptr2int instructions will not alter the
value of their operand and can therefore be looked through to determine
non-nullness.


Repository:
  rL LLVM

https://reviews.llvm.org/D54956

Files:
  lib/Analysis/ValueTracking.cpp


Index: lib/Analysis/ValueTracking.cpp
===================================================================
--- lib/Analysis/ValueTracking.cpp
+++ lib/Analysis/ValueTracking.cpp
@@ -2016,6 +2016,18 @@
     if (isKnownNonNullFromDominatingCondition(V, Q.CxtI, Q.DT))
       return true;
 
+    {
+      // Look through operations that do not alter the value.
+      if (const BitCastOperator *BCO = dyn_cast<BitCastOperator>(V))
+        return isKnownNonZero(BCO->getOperand(0), Depth, Q);
+
+      if (const AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(V))
+        return isKnownNonZero(ASC->getPointerOperand(), Depth, Q);
+
+      if (const PtrToIntOperator *P2I = dyn_cast<PtrToIntOperator>(V))
+        return isKnownNonZero(P2I->getPointerOperand(), Depth, Q);
+    }
+
     if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V))
       if (isGEPKnownNonNull(GEP, Depth, Q))
         return true;


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