[PATCH] D73883: HexagonOptAddrMode::changeStore - fix null dereference warning (PR43463)

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon created this revision.
RKSimon added a reviewer: kparzysz.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.

As detailed on PR43463, this fixes a static analyzer null dereference warning by sinking Changed = true into the if() blocks where the MIB is actually created.

I did a quick check that suggested that one of those if() blocks is always guaranteed to be hit (so we could change it to if-else), but this seems like a safer approach.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D73883

Files:
  llvm/lib/Target/Hexagon/HexagonOptAddrMode.cpp


Index: llvm/lib/Target/Hexagon/HexagonOptAddrMode.cpp
===================================================================
--- llvm/lib/Target/Hexagon/HexagonOptAddrMode.cpp
+++ llvm/lib/Target/Hexagon/HexagonOptAddrMode.cpp
@@ -561,6 +561,7 @@
       MIB.add(ImmOp);
       MIB.add(OldMI->getOperand(3));
       OpStart = 4;
+      Changed = true;
     } else if (HII->getAddrMode(*OldMI) == HexagonII::BaseImmOffset) {
       short NewOpCode = HII->changeAddrMode_io_abs(*OldMI);
       assert(NewOpCode >= 0 && "Invalid New opcode\n");
@@ -570,10 +571,8 @@
       MIB.addGlobalAddress(GV, Offset, ImmOp.getTargetFlags());
       MIB.add(OldMI->getOperand(2));
       OpStart = 3;
+      Changed = true;
     }
-    Changed = true;
-    LLVM_DEBUG(dbgs() << "[Changing]: " << *OldMI << "\n");
-    LLVM_DEBUG(dbgs() << "[TO]: " << *MIB << "\n");
   } else if (ImmOpNum == 1 && OldMI->getOperand(2).getImm() == 0) {
     short NewOpCode = HII->changeAddrMode_rr_io(*OldMI);
     assert(NewOpCode >= 0 && "Invalid New opcode\n");
@@ -582,12 +581,14 @@
     MIB.add(ImmOp);
     OpStart = 3;
     Changed = true;
+  }
+  if (Changed) {
     LLVM_DEBUG(dbgs() << "[Changing]: " << *OldMI << "\n");
     LLVM_DEBUG(dbgs() << "[TO]: " << *MIB << "\n");
-  }
-  if (Changed)
+
     for (unsigned i = OpStart; i < OpEnd; ++i)
       MIB.add(OldMI->getOperand(i));
+  }
 
   return Changed;
 }


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