src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.nodes/src/org/graalvm/compiler/nodes/calc/ZeroExtendNode.java

*** 104,127 ****
              return new ZeroExtendNode(other.getValue(), other.getInputBits(), getResultBits());
          }
          if (forValue instanceof NarrowNode) {
              NarrowNode narrow = (NarrowNode) forValue;
              Stamp inputStamp = narrow.getValue().stamp();
!             if (inputStamp instanceof IntegerStamp && inputStamp.isCompatible(stamp())) {
                  IntegerStamp istamp = (IntegerStamp) inputStamp;
                  long mask = CodeUtil.mask(PrimitiveStamp.getBits(narrow.stamp()));
!                 if (((istamp.upMask() | istamp.downMask()) & ~mask) == 0) {
!                     // The original value is in the range of the masked zero extended result so
!                     // simply return the original input.
                      return narrow.getValue();
                  }
              }
          }
  
          return this;
      }
  
      @Override
      public void generate(NodeLIRBuilderTool nodeValueMap, ArithmeticLIRGeneratorTool gen) {
          nodeValueMap.setResult(this, gen.emitZeroExtend(nodeValueMap.operand(getValue()), getInputBits(), getResultBits()));
      }
  }
--- 104,143 ----
              return new ZeroExtendNode(other.getValue(), other.getInputBits(), getResultBits());
          }
          if (forValue instanceof NarrowNode) {
              NarrowNode narrow = (NarrowNode) forValue;
              Stamp inputStamp = narrow.getValue().stamp();
!             if (inputStamp instanceof IntegerStamp) {
                  IntegerStamp istamp = (IntegerStamp) inputStamp;
                  long mask = CodeUtil.mask(PrimitiveStamp.getBits(narrow.stamp()));
! 
!                 if ((istamp.upMask() & ~mask) == 0) {
!                     // The original value cannot change because of the narrow and zero extend.
! 
!                     if (istamp.getBits() < resultBits) {
!                         // Need to keep the zero extend, skip the narrow.
!                         return create(narrow.getValue(), resultBits);
!                     } else if (istamp.getBits() > resultBits) {
!                         // Need to keep the narrow, skip the zero extend.
!                         return NarrowNode.create(narrow.getValue(), resultBits);
!                     } else {
!                         assert istamp.getBits() == resultBits;
!                         // Just return the original value.
                          return narrow.getValue();
                      }
                  }
              }
+         }
  
          return this;
      }
  
      @Override
      public void generate(NodeLIRBuilderTool nodeValueMap, ArithmeticLIRGeneratorTool gen) {
          nodeValueMap.setResult(this, gen.emitZeroExtend(nodeValueMap.operand(getValue()), getInputBits(), getResultBits()));
      }
+ 
+     @Override
+     public boolean mayNullCheckSkipConversion() {
+         return true;
+     }
  }