fix a buggy check that accidentally disabled this xform

llvm-svn: 30967
diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
index 739493e..6654daf 100644
--- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -1973,7 +1973,7 @@
       // -(X sdiv C)  -> (X sdiv -C)
       if (Op1I->getOpcode() == Instruction::Div)
         if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
-          if (CSI->isNullValue())
+          if (!CSI->isNullValue())
             if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
               return BinaryOperator::createDiv(Op1I->getOperand(0),
                                                ConstantExpr::getNeg(DivRHS));