[ValueTracking] Add a new predicate: isKnownNonEqual()

[oota-llvm.git] / lib / Analysis / InstructionSimplify.cpp

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 8175fbd76d64245c863a0f1ec5d427dc44759509..be5ce2960ea8d49ddb4ddc8ffccc8034dbbfbb8e 100644 (file)
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -2642,6 +2642,14 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
     }
   }
 
+  // icmp eq|ne X, Y -> false|true if X != Y
+  if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE) &&
+      isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT)) {
+    LLVMContext &Ctx = LHS->getType()->getContext();
+    return Pred == ICmpInst::ICMP_NE ?
+      ConstantInt::getTrue(Ctx) : ConstantInt::getFalse(Ctx);
+  }
+  
   // Special logic for binary operators.
   BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
   BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);