[9] RFR(M): 8078554: Compiler: implement ranges (optionally constraints) for those flags that have them missing
Zoltán Majó
zoltan.majo at oracle.com
Thu Oct 8 15:52:39 UTC 2015
Thank you, Tobias, for the review!
Best regards,
Zoltán
On 10/08/2015 04:10 PM, Tobias Hartmann wrote:
> Hi Zoltán,
>
> On 08.10.2015 14:07, Zoltán Majó wrote:
>> Hi Tobias,
>>
>>
>> thank you for the feedback!
>>
>> On 10/07/2015 03:38 PM, Tobias Hartmann wrote:
>>> Hi Zoltan,
>>>
>>> I had a look at your changes and just spotted some minor things:
>>>
>>> globals_sparc.hpp:
>>> - I think there is a '\' missing in line 119
>> thank you for spotting that!
>>
>>> globals_x86.hpp:
>>> - Isn't this also a compiler flag we should add range checks for?
>>> 136 product(uintx, RTMRetryCount, 5,
>> JEP 245 considers it as a runtime flag and JDK-8078556 "Runtime: implement ranges..." [1] will take care of it. But you are right, that flag could be also considered a compiler flag.
> Okay, thanks for pointing that out.
>
>>> commandLineFlagConstraintsCompiler.cpp:
>>> - I think there is a "rule" that the include statements should be in alphabetical order
>> Yes, I think there is such a rule (or convention). I diverged from the rule because the include of code/relocInfo.hpp depends on 'os', 'vm_page_size', and 'Metadata'. Therefore, "oops/metadata.hpp" and "runtime/os.hpp" must be included before relocInfo.hpp (otherwise the Solaris compiler complains). The remaining includes are ordered alphabetically.
> Okay, makes sense.
>
>>> - the indentation is wrong here:
>>> 179 return Flag::VIOLATES_CONSTRAINT;
>> I updated the indentation.
>>
>> Here is the updated webrev:
>> http://cr.openjdk.java.net/~zmajo/8078554/webrev.02/
>>
>> I re-tested the updated webrev with JPRT (testset hotspot), all tests pass.
> Looks good to me (not a Reviewer).
>
> Best,
> Tobias
>
>
>> Thank you and best regards,
>>
>>
>> Zoltan
>>
>> [1] https://bugs.openjdk.java.net/browse/JDK-8078556
>>> Best,
>>> Tobias
>>
>>> On 06.10.2015 13:45, Zoltán Majó wrote:
>>>> Hi Roland,
>>>>
>>>>
>>>> thank you for the feedback!
>>>>
>>>> On 10/02/2015 03:55 PM, Roland Westrelin wrote:
>>>>> Hi Zoltan,
>>>>>
>>>>>> Webrev:http://cr.openjdk.java.net/~zmajo/8078554/
>>>>> c2_globals.hpp
>>>>>
>>>>> That one is not correct:
>>>>> 461 product(intx, MaxNodeLimit, 80000, \
>>>>> 462 "Maximum number of nodes") \
>>>>> 463 range(1000, 80000) \
>>>>>
>>>>> I think the upper bound should be max_juint
>>>> You are right that the limit of 80'000 is too conservative. But max_j*u*int as an upper bound would cause an overflow when parsing the flag's value, because on 32-bit machines intx is a 32-bit signed integer.
>>>>
>>>> Using max_jint instead of max_j*u*int as an upper bound would not cause an overflow at parse time. However, in Parse::do_call() the maximum node limit is increased by 3 times for jsr292 users
>>>>
>>>> C->set_max_node_limit(3*MaxNodeLimit);
>>>>
>>>> If MaxNodeLimit == max_jint, this expression will overflow, I think.
>>>>
>>>> So I set the limit to (max_jint / 3) in the updated webrev.
>>>>
>>>> If we would set MaxNodeLimit to max_j*u*int / 3 (instead of max_jint / 3), the expression 3 * MaxNodeLimit would overflow as well. Changing the type of the flag from intx to uintx could let use use max_j*u*int / 3 as an upper bound, but that is most likely not worth the effort.
>>>>
>>>>> 699 product(intx, LiveNodeCountInliningCutoff, 40000, \
>>>>> 700 "max number of live nodes in a method") \
>>>>> 701 range(0, max_juint / 8) \
>>>>>
>>>>> Out of curiosity why max_juint / 8 (not that it makes much of a difference)?
>>>> In Compile::inline_incrementally, the 80% of LiveNodeCountInliningCutoff is computed the following way:
>>>>
>>>> if (low_live_nodes < (uint)LiveNodeCountInliningCutoff * 8 / 10) {
>>>>
>>>> If LiveNodeCountInliningCutoff == max_juint, we'd have an overflow because of the multiplication by 8.
>>>>
>>>>> arguments.cpp
>>>>>
>>>>> 1099 Tier3InvokeNotifyFreqLog = 0;
>>>>> 1100 Tier4InvocationThreshold = 0;
>>>>>
>>>>> Why that change?
>>>> I proposed that change because I misread the code. I reverted that change and also changed the range of all Tier*FreqLog flags from range(1, 30) to range(0, 30).
>>>>
>>>>> globals.hp
>>>>>
>>>>> 2870 product_pd(uintx, TypeProfileLevel, \
>>>>> 2871 "=XYZ, with Z: Type profiling of arguments at call; " \
>>>>> 2872 "Y: Type profiling of return value at call; " \
>>>>> 2873 "X: Type profiling of parameters to methods; " \
>>>>> 2874 "X, Y and Z in 0=off ; 1=jsr292 only; 2=all methods") \
>>>>> 2875 range(0, 222)
>>>>>
>>>>> Legal values are 0, 1, 2, 10, 11, 12, 100, 101, 102, 110, 111, 112 etc.
>>>>>
>>>>> 70 is not for instance. So range(0, 222) is incorrect.
>>>> I agree. I removed the range check and implemented a constraint function instead (TypeProfileLevelConstraintFunc).
>>>>
>>>>> 2877 product(intx, TypeProfileArgsLimit, 2, \
>>>>> 2878 "max number of call arguments to consider for type profiling") \
>>>>> 2879 range(0, 16) \
>>>>>
>>>>> 2880 \
>>>>> 2881 product(intx, TypeProfileParmsLimit, 2, \
>>>>> 2882 "max number of incoming parameters to consider for type profiling"\
>>>>> 2883 ", -1 for all") \
>>>>> 2884 range(-1, 64)
>>>>>
>>>>> Why 16 and 64?
>>>> These are the largest values that work on all platforms we support.
>>>>
>>>> Here is the updated webrev: http://cr.openjdk.java.net/~zmajo/8078554/webrev.01/
>>>>
>>>> I repeated the testing with JPRT. I also executed the currently disabled TestOptionsWithRanges.java test on all platforms we support. All tests pass.
>>>>
>>>> Thank you and best regards,
>>>>
>>>>
>>>> Zoltan
>>>>
>>>>> Roland.
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