[PATCH] D14721: patch for missed constantFold optimization in InstCombine

[Tejas via llvm-commits]

optimusPrime created this revision.
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llvm::ConstantFoldCompareInstOperands misses an optimization when it tries to constantFold a compare instruction containing addrspacecast instead of combination of ptrtoint and inttoptr. Adding the patched code snippet in the code would enable the pass to handle addrspacecast and constantFold the missing cases.
Attached is the reproducer. Let me know if there are any suggestions/comments.{F1101148}

http://reviews.llvm.org/D14721

Files:
  ConstantFolding.cpp
  llvm/trunk/lib/Analysis/ConstantFolding.cpp

Index: llvm/trunk/lib/Analysis/ConstantFolding.cpp
===================================================================
--- llvm/trunk/lib/Analysis/ConstantFolding.cpp
+++ llvm/trunk/lib/Analysis/ConstantFolding.cpp
@@ -1137,6 +1137,12 @@
           return ConstantFoldCompareInstOperands(Predicate, C, Null, DL, TLI);
         }
       }
+      
+      if (CE0->getOpcode() == Instruction::AddrSpaceCast) {
+          Constant *C = CE0->getOperand(0);
+          Constant *Null = Constant::getNullValue(C->getType());
+          return ConstantFoldCompareInstOperands(Predicate, C, Null, TD, TLI);
+      }
     }
 
     if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(Ops1)) {


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