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test/hotspot/jtreg/runtime/exceptionMsgs/NullPointerException/NullPointerExceptionTest.java
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rev 56326 : 8218628: Add detailed message to NullPointerException describing what is null.
Summary: This is the implementation of JEP 358: Helpful NullPointerExceptions.
Reviewed-by: coleenp, clanger, rschmelter
rev 56327 : [mq]: find_local_stores.patch
@@ -60,13 +60,18 @@
import jdk.test.lib.Asserts;
import static java.lang.invoke.MethodHandles.lookup;
import static jdk.internal.org.objectweb.asm.Opcodes.ACC_PUBLIC;
import static jdk.internal.org.objectweb.asm.Opcodes.ACC_SUPER;
+import static jdk.internal.org.objectweb.asm.Opcodes.ACONST_NULL;
import static jdk.internal.org.objectweb.asm.Opcodes.ALOAD;
+import static jdk.internal.org.objectweb.asm.Opcodes.ASTORE;
import static jdk.internal.org.objectweb.asm.Opcodes.GETFIELD;
+import static jdk.internal.org.objectweb.asm.Opcodes.GETSTATIC;
+import static jdk.internal.org.objectweb.asm.Opcodes.ICONST_1;
import static jdk.internal.org.objectweb.asm.Opcodes.INVOKESPECIAL;
+import static jdk.internal.org.objectweb.asm.Opcodes.INVOKEVIRTUAL;
import static jdk.internal.org.objectweb.asm.Opcodes.IRETURN;
import static jdk.internal.org.objectweb.asm.Opcodes.RETURN;
/**
* Tests NullPointerExceptions
@@ -1421,10 +1426,20 @@
// Generates:
// class E implements E0 {
// public int throwNPE(F f) {
// return f.i;
// }
+ // public void throwNPE_reuseStackSlot1(String s1) {
+ // System.out.println(s1.substring(1));
+ // String s1_2 = null; // Reuses slot 1.
+ // System.out.println(s1_2.substring(1));
+ // }
+ // public void throwNPE_reuseStackSlot4(String s1, String s2, String s3, String s4) {
+ // System.out.println(s4.substring(1));
+ // String s4_2 = null; // Reuses slot 4.
+ // System.out.println(s4_2.substring(1));
+ // }
// }
static byte[] generateTestClass() {
ClassWriter cw = new ClassWriter(0);
MethodVisitor mv;
@@ -1454,15 +1469,90 @@
mv.visitLocalVariable("this", "LE;", null, label0, label1, 0);
mv.visitLocalVariable("f", "LE;", null, label0, label1, 1);
mv.visitMaxs(1, 2);
mv.visitEnd();
}
+
+ {
+ mv = cw.visitMethod(ACC_PUBLIC, "throwNPE_reuseStackSlot1", "(Ljava/lang/String;)V", null, null);
+ mv.visitCode();
+ Label label0 = new Label();
+ mv.visitLabel(label0);
+ mv.visitLineNumber(7, label0);
+ mv.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
+ mv.visitVarInsn(ALOAD, 1);
+ mv.visitInsn(ICONST_1);
+ mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/String", "substring", "(I)Ljava/lang/String;", false);
+ mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false);
+ Label label1 = new Label();
+ mv.visitLabel(label1);
+ mv.visitLineNumber(8, label1);
+ mv.visitInsn(ACONST_NULL);
+ mv.visitVarInsn(ASTORE, 1);
+ Label label2 = new Label();
+ mv.visitLabel(label2);
+ mv.visitLineNumber(9, label2);
+ mv.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
+ mv.visitVarInsn(ALOAD, 1);
+ mv.visitInsn(ICONST_1);
+ mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/String", "substring", "(I)Ljava/lang/String;", false);
+ mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false);
+ Label label3 = new Label();
+ mv.visitLabel(label3);
+ mv.visitLineNumber(10, label3);
+ mv.visitInsn(RETURN);
+ mv.visitMaxs(3, 3);
+ mv.visitEnd();
+ }
+
+ {
+ mv = cw.visitMethod(ACC_PUBLIC, "throwNPE_reuseStackSlot4", "(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)V", null, null);
+ mv.visitCode();
+ Label label0 = new Label();
+ mv.visitLabel(label0);
+ mv.visitLineNumber(12, label0);
+ mv.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
+ mv.visitVarInsn(ALOAD, 4);
+ mv.visitInsn(ICONST_1);
+ mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/String", "substring", "(I)Ljava/lang/String;", false);
+ mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false);
+ Label label1 = new Label();
+ mv.visitLabel(label1);
+ mv.visitLineNumber(13, label1);
+ mv.visitInsn(ACONST_NULL);
+ mv.visitVarInsn(ASTORE, 4);
+ Label label2 = new Label();
+ mv.visitLabel(label2);
+ mv.visitLineNumber(14, label2);
+ mv.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
+ mv.visitVarInsn(ALOAD, 4);
+ mv.visitInsn(ICONST_1);
+ mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/String", "substring", "(I)Ljava/lang/String;", false);
+ mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false);
+ Label label3 = new Label();
+ mv.visitLabel(label3);
+ mv.visitLineNumber(15, label3);
+ mv.visitInsn(RETURN);
+ mv.visitMaxs(3, 6);
+ mv.visitEnd();
+ }
+
cw.visitEnd();
return cw.toByteArray();
}
+ // Assign to a parameter.
+ // Without debug information, this will print "parameter1" if a NPE
+ // is raised in the first line because null was passed to the method.
+ // It will print "local1" if a NPE is raised in line three.
+ public void assign_to_parameter(String s1) {
+ System.out.println(s1.substring(1));
+ s1 = null;
+ System.out.println(s1.substring(2));
+ }
+
// Tests that a class generated on the fly is handled properly.
public void testGeneratedCode() throws Exception {
byte[] classBytes = generateTestClass();
Lookup lookup = lookup();
Class<?> clazz = lookup.defineClass(classBytes);
@@ -1472,16 +1562,83 @@
} catch (NullPointerException ex) {
checkMessage(ex, "return f.i;",
ex.getMessage(),
"Cannot read field 'i' because 'f' is null.");
}
+
+ // Optimized bytecode can reuse local variable slots for several
+ // local variables.
+ // If there is no variable name information, we print 'parameteri'
+ // if a parameter maps to a local slot. Once a local slot has been
+ // written, we don't know any more whether it was written as the
+ // corresponding parameter, or whether another local has been
+ // mapped to the slot. So we don't want to print 'parameteri' any
+ // more, but 'locali'. Similary for 'this'.
+
+ // Expect message saying "parameter0".
+ try {
+ e.throwNPE_reuseStackSlot1(null);
+ } catch (NullPointerException ex) {
+ checkMessage(ex, "s1.substring(1)",
+ ex.getMessage(),
+ "Cannot invoke 'String.substring(int)' because '<parameter1>' is null.");
+ }
+ // Expect message saying "local0".
+ try {
+ e.throwNPE_reuseStackSlot1("aa");
+ } catch (NullPointerException ex) {
+ checkMessage(ex, "s1_2.substring(1)",
+ ex.getMessage(),
+ "Cannot invoke 'String.substring(int)' because '<local1>' is null.");
+ }
+ // Expect message saying "parameter4".
+ try {
+ e.throwNPE_reuseStackSlot4("aa", "bb", "cc", null);
+ } catch (NullPointerException ex) {
+ checkMessage(ex, "s4.substring(1)",
+ ex.getMessage(),
+ "Cannot invoke 'String.substring(int)' because '<parameter4>' is null.");
+ }
+ // Expect message saying "local4".
+ try {
+ e.throwNPE_reuseStackSlot4("aa", "bb", "cc", "dd");
+ } catch (NullPointerException ex) {
+ checkMessage(ex, "s4_2.substring(1)",
+ ex.getMessage(),
+ "Cannot invoke 'String.substring(int)' because '<local4>' is null.");
+ }
+
+ // Unfortunately, with the fix for optimized code as described above
+ // we don't write 'parameteri' any more after the parameter variable
+ // has been assigned.
+
+ if (!hasDebugInfo) {
+ // Expect message saying "parameter1".
+ try {
+ assign_to_parameter(null);
+ } catch (NullPointerException ex) {
+ checkMessage(ex, "s1.substring(1)",
+ ex.getMessage(),
+ "Cannot invoke 'String.substring(int)' because '<parameter1>' is null.");
+ }
+ // The message says "local1" although "parameter1" would be correct.
+ try {
+ assign_to_parameter("aaa");
+ } catch (NullPointerException ex) {
+ checkMessage(ex, "s1.substring(2)",
+ ex.getMessage(),
+ "Cannot invoke 'String.substring(int)' because '<local1>' is null.");
+ }
+ }
}
}
// Helper interface for test cases needed for generateTestClass().
interface E0 {
public int throwNPE(F f);
+ public void throwNPE_reuseStackSlot1(String s1);
+ public void throwNPE_reuseStackSlot4(String s1, String s2, String s3, String s4);
}
// Helper class for test cases needed for generateTestClass().
class F {
int i;
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