[9] RFR(M): 8078554: Compiler: implement ranges (optionally constraints) for those flags that have them missing

[Tobias Hartmann]

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.
>