RFR XXS (8185826) HotSpot build failure with GCC 7.1.1

[David Holmes]

Hi Ioi,

On 4/08/2017 2:50 PM, Ioi Lam wrote:
> On 8/3/17 7:00 PM, David Holmes wrote:
> 
>> Hi Yasumasa,
>>
>> On 4/08/2017 10:49 AM, Yasumasa Suenaga wrote:
>>> Thanks Kim, David,
>>>
>>> I filed this issue to JBS and uploaded webrev. Could you review it?
>>>
>>> http://cr.openjdk.java.net/~ysuenaga/JDK-8185826/webrev.00/
>>
>> I'm still at a loss to understand how the current code even 
>> compiles/links at all with any version of the compiler. ??
>>
> Hi Yasumasa, thanks for noticing this.
> 
> Sorry, it was my bug. I checked this in as part of JDK-8072061 on Tuesday.
> 
> Apparently older C++ compilers are quite lenient when compiling template 
> declarations that aren't instantiated. Here's a test case:
> 
> template <typename T> class X {
>    static int size() {
>      return align_size_up(byte_sizeof());
>    }
>    static int byte_sizeof() {
>      return sizeof(T);
>    }
> };
> 
> # from gcc 5.4:
> $ gcc -c ~/t.cpp && echo $?
> 0
> 
> In our case, presumably, gcc will detect the error when an instantiated 
> Array<T> type access the size(int, int) method.

Ah I see.

> However, I added this function during my development, but didn't need it 
> after all. So this function was never referenced, so all of our existing 
> compilers never had a chance to generate an error for
> 
> I removed this function and HotSpot built with no error.
> 
> $ hg diff
> diff -r 731370f39fcd src/share/vm/oops/array.hpp
> --- a/src/share/vm/oops/array.hpp    Wed Aug 02 18:06:38 2017 -0700
> +++ b/src/share/vm/oops/array.hpp    Thu Aug 03 21:47:41 2017 -0700
> @@ -134,10 +134,6 @@
> 
>       return (int)words;
>     }
> -  static int size(int length, int elm_byte_size) {
> -    return align_size_up(byte_sizeof(length, elm_byte_size), 
> BytesPerWord) / BytesPerWord; // FIXME
> -  }
> -
>     int size() {
>       return size(_length);
>     }
> 
> 
> So I think proper fix is to just remove this function.

Sounds good to me. Reviewed!

Thanks,
David

> Thanks
> - Ioi
> 
> 
> 
> 
>> You removed a "// FIXME" comment - what was that referring to ??
>>
>> Thanks,
>> David
>>
>>> I cannot access JPRT. So I need a sponsor.
>>>
>>>
>>> Yasumasa
>>>
>>>
>>>
>>> 2017-08-04 9:08 GMT+09:00 Kim Barrett <kim.barrett at oracle.com>:
>>>>> On Aug 3, 2017, at 7:12 PM, David Holmes <david.holmes at oracle.com> 
>>>>> wrote:
>>>>> I can't even see a definition of align_size_up - where is it coming 
>>>>> from ???
>>>>
>>>> It was recently removed.
>>>>
>>>> 8178499: Remove _ptr_ and _size_ infixes from align functions
>>>>
>