collection of small fixes from running runtime tests with -Xcomp

Frederic Parain frederic.parain at oracle.com
Wed Mar 15 17:09:20 UTC 2017


> On Mar 15, 2017, at 06:29, Zoltán Majó <zoltan.majo at oracle.com> wrote:
> 
> Hi,
> 
> 
> On 03/15/2017 09:00 AM, Tobias Hartmann wrote:
>> Hi Roland,
>> 
>> On 14.03.2017 17:16, Roland Westrelin wrote:
>>> [...]
>>> 
>>> Sometimes a lambda form compiled as the root of a compilation has a
>>> signature with object parameters but is passed a value type: so it's
>>> passed fields but has no way to know. This could be fixed by always
>>> passing value types as references when the target is a lambda form. But
>>> then, method handles intrinsics could get reference inputs and call a
>>> method that expects value types to be passed as fields. So the code in
>>> MethodHandles::generate_method_handle_dispatch() would need to be
>>> adjusted to shuffle arguments. That all sounds too complicated so
>>> instead I disallowed lambda form as root of compilations.
>> I wonder if it's okay to treat value types as objects in such cases.
>> 
>> Zoltan, you found some related problems right?
> 
> Yes. A version of Maurizio's PointValues program triggered an error in C2's type system.
> 
> The test attempted to pass a Q-type to an MethodHandle.invoke(Object o). That results in a type system error at the moment, as C2 considers a Q-type and and L-type to be "unrelated". (The test would, of course work, if the Q-type was first boxed to the matching L-type before calling the invoke method.)
> 
> So maybe the question is: Is a value type a subclass of a java.lang.Object? If yes, we should make C2 aware of that. If not, then I think it's a good idea to bail out compilation if the compiler detects that a Q-type is used in place of an L-type.

A value type is *not* a subclass of java.lang.Object.
The box of a value type is a subclass of java.lang.Object, and has a L-type signature.


> Currently, an L-type and the matching Q-type have the same memory layout, so we could treat them as being the same. But by starting to doing so we'll most likely encounter some difficult-to-trace errors. So I'm more for bailing out compilations (or updating the type system to consider Q-types as subclasses of java.lang.Object).
> 

They have a similar layout, but they don’t have the same behavior nor the same methods:
all L-types inherit a set of methods from java.lang.Object. Q-type don’t have any of them.
So, trying to handle a Q-type pretending is a L-type is a slippery slope to disaster.

Fred

> Best regards,
> 
> 
> Zoltan
> 
>> 
>> I think it would make sense to add "-Xcomp -XX:-TieredCompilation" to the runtime tests (I did that before, see patch below).
>> 
>> Thanks,
>> Tobias
>> 
>> 
>> --- old/test/runtime/valhalla/valuetypes/DeriveValueTypeCreation.java	2017-03-15 08:54:48.004842144 +0100
>> +++ new/test/runtime/valhalla/valuetypes/DeriveValueTypeCreation.java	2017-03-15 08:54:47.936842147 +0100
>> @@ -43,6 +43,7 @@
>>   * @library /testlibrary /
>>   * @build runtime.valhalla.valuetypes.ValueCapableClass
>>   * @run main/othervm -Xint -noverify runtime.valhalla.valuetypes.DeriveValueTypeCreation
>> + * @run main/othervm -Xcomp -XX:-TieredCompilation -noverify runtime.valhalla.valuetypes.DeriveValueTypeCreation
>>   */
>>  public class DeriveValueTypeCreation {
>>  --- old/test/runtime/valhalla/valuetypes/InvokeDirect.java	2017-03-15 08:54:48.256842132 +0100
>> +++ new/test/runtime/valhalla/valuetypes/InvokeDirect.java	2017-03-15 08:54:48.188842136 +0100
>> @@ -7,6 +7,7 @@
>>   * @summary Value Type invokedirect bytecode test (incomplete until type system defn done)
>>   * @library /testlibrary /
>>   * @run main/othervm -noverify -Xint runtime.valhalla.valuetypes.InvokeDirect
>> + * @run main/othervm -noverify -Xcomp -XX:-TieredCompilation runtime.valhalla.valuetypes.InvokeDirect
>>   */
>>  public class InvokeDirect {
>>      public static void main(String[] args) {
>> --- old/test/runtime/valhalla/valuetypes/VDefaultTest.java	2017-03-15 08:54:48.512842121 +0100
>> +++ new/test/runtime/valhalla/valuetypes/VDefaultTest.java	2017-03-15 08:54:48.444842124 +0100
>> @@ -30,6 +30,7 @@
>>   * @summary vdefault bytecode test
>>   * @library /testlibrary /
>>   * @run main/othervm -noverify -Xint runtime.valhalla.valuetypes.VDefaultTest
>> + * @run main/othervm -noverify -Xcomp -XX:-TieredCompilation runtime.valhalla.valuetypes.VDefaultTest
>>   */
>>    public class VDefaultTest {
>> --- old/test/runtime/valhalla/valuetypes/VWithFieldTest.java	2017-03-15 08:54:48.756842109 +0100
>> +++ new/test/runtime/valhalla/valuetypes/VWithFieldTest.java	2017-03-15 08:54:48.692842112 +0100
>> @@ -30,6 +30,7 @@
>>   * @summary vwithfield bytecode test
>>   * @library /testlibrary /
>>   * @run main/othervm -noverify -Xint runtime.valhalla.valuetypes.VWithFieldTest
>> + * @run main/othervm -noverify -Xcomp -XX:-TieredCompilation runtime.valhalla.valuetypes.VWithFieldTest
>>   */
>>    public class VWithFieldTest {
>> --- old/test/runtime/valhalla/valuetypes/ValueTypeArray.java	2017-03-15 08:54:49.000842098 +0100
>> +++ new/test/runtime/valhalla/valuetypes/ValueTypeArray.java	2017-03-15 08:54:48.936842101 +0100
>> @@ -33,6 +33,8 @@
>>   * @library /testlibrary /
>>   * @run main/othervm -noverify -Xint -XX:+ValueArrayFlatten runtime.valhalla.valuetypes.ValueTypeArray
>>   * @run main/othervm -noverify -Xint -XX:-ValueArrayFlatten runtime.valhalla.valuetypes.ValueTypeArray
>> + * @run main/othervm -noverify -Xcomp -XX:-TieredCompilation -XX:+ValueArrayFlatten runtime.valhalla.valuetypes.ValueTypeArray
>> + * @run main/othervm -noverify -Xcomp -XX:-TieredCompilation -XX:-ValueArrayFlatten runtime.valhalla.valuetypes.ValueTypeArray
>>   */
>>  public class ValueTypeArray {
>>      public static void main(String[] args) {
>> --- old/test/runtime/valhalla/valuetypes/ValueTypeCreation.java	2017-03-15 08:54:49.248842086 +0100
>> +++ new/test/runtime/valhalla/valuetypes/ValueTypeCreation.java	2017-03-15 08:54:49.180842089 +0100
>> @@ -7,6 +7,7 @@
>>   * @summary Value Type creation test
>>   * @library /testlibrary /
>>   * @run main/othervm -noverify -Xint runtime.valhalla.valuetypes.ValueTypeCreation
>> + * @run main/othervm -noverify -Xcomp -XX:-TieredCompilation runtime.valhalla.valuetypes.ValueTypeCreation
>>   */
>>  public class ValueTypeCreation {
>>      public static void main(String[] args) {
>> --- old/test/runtime/valhalla/valuetypes/ValueTypeDensity.java	2017-03-15 08:54:49.496842075 +0100
>> +++ new/test/runtime/valhalla/valuetypes/ValueTypeDensity.java	2017-03-15 08:54:49.428842078 +0100
>> @@ -36,6 +36,7 @@
>>   * @run driver ClassFileInstaller sun.hotspot.WhiteBox
>>   *                                sun.hotspot.WhiteBox$WhiteBoxPermission
>>   * @run main/othervm -noverify -Xint -XX:+ValueArrayFlatten -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI ValueTypeDensity
>> + * @run main/othervm -noverify -Xcomp -XX:-TieredCompilation -XX:+ValueArrayFlatten -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI ValueTypeDensity
>>   */
>>    public class ValueTypeDensity {
>> --- old/test/runtime/valhalla/valuetypes/ValueTypeGetField.java	2017-03-15 08:54:49.752842063 +0100
>> +++ new/test/runtime/valhalla/valuetypes/ValueTypeGetField.java	2017-03-15 08:54:49.684842066 +0100
>> @@ -7,6 +7,7 @@
>>   * @summary Value Type get field test
>>   * @library /testlibrary /
>>   * @run main/othervm -noverify -Xint runtime.valhalla.valuetypes.ValueTypeGetField
>> + * @run main/othervm -noverify -Xcomp -XX:-TieredCompilation runtime.valhalla.valuetypes.ValueTypeGetField
>>   */
>>  public class ValueTypeGetField {
>>  --- old/test/runtime/valhalla/valuetypes/VboxUnbox.java	2017-03-15 08:54:50.008842051 +0100
>> +++ new/test/runtime/valhalla/valuetypes/VboxUnbox.java	2017-03-15 08:54:49.940842054 +0100
>> @@ -33,6 +33,7 @@
>>   * @library /testlibrary /
>>   * @build runtime.valhalla.valuetypes.ValueCapableClass
>>   * @run main/othervm -Xint -noverify runtime.valhalla.valuetypes.VboxUnbox
>> + * @run main/othervm -Xcomp -XX:-TieredCompilation -noverify runtime.valhalla.valuetypes.VboxUnbox
>>   *
>>   * To dump generated byte-code, add "-Dvalhalla.dumpIsolatedMethodClasses=/tmp/foo"
>>   */



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