Request for review: 7102489: RFE: cleanup jlong typedef on __APPLE__ and _LP64 systems

harold seigel harold.seigel at
Tue Jan 15 11:02:11 PST 2013


Thank you for the comments.  I think there are two remaining minor 
issues.  Let me know if I missed anything.

1. Use int64_t, instead of long, to define jlong?

    I prefer using 'long' to define 'jlong', rather than 'int64_t',
    because 'long' is a predefined C++ language type.  Type 'int64_t' is
    a Unix operating system defined type.  This would unnecessarily
    complicate things.  For example, defining 'jlong' as 'int64_t' would
    require moving the definition of 'jlong' from
    src/cpu/x86/vm/jni_x86.h to files in the src/os_cpu/ directories.

    Would it be useful to file a new bug to investigate using 'int64_t'
    to define 'jlong' ?

2. Define 32-bit and 64-bit variants of JLONG_FORMAT in 
src/os/posix/launcher/java_md.h ?

      Would it be better to define JLONG_FORMAT as %lld for 32-bit and
    %ld for 64-bit for the posix variant, in file java_md.h?  I'm
    unclear what the Windows variant of "%I64d" would be.

Thanks, Harold

On 1/14/2013 2:10 PM, Mikael Vidstedt wrote:
> On 2013-01-12 15:05, David Holmes wrote:
>> Sorry Harold I didn't see this before my other reply. Now I 
>> understand your problem. We either have to:
>> a) typedef long long jlong on all platforms; or
>> b) special case the typedef for jlong on Apple; or
>> c) special case the typedef for JLONG_FORMAT on Apple
>> But even if we do (a) any platform that defines int64_t differently 
>> to our jlong will mean we still need distinct format specifiers. 
>> Further unless we know how int64_t is defined on a given platform we 
>> don't know what format specifier to use (%ld or %lld).
>> Do compilers that provide things like int64_t also define a format 
>> specifier macro?
> It's part of the C99 standard (not sure about c++) - the types have 
> corresponding format specifier macros called PRI*, defined in 
> inttypes.h. For example PRId64, PRIu64 or PRIx64 can be used to print 
> the int64_t/uint64_t equivalents of %d, %u and %x respectively. Our 
> own internal format macros (SIZE_FORMAT, INTPTR_FORMAT etc) are 
> defined as derivatives of these.
> In general "long" tends to be a mess... :(
> /Mikael
>> David
>> -----
>> On 12/01/2013 12:36 AM, harold seigel wrote:
>>> Hi Vladimir,
>>> Thank you for your comments.  Mac OS defines int64_t as 'long long'.
>>> So, int64_t needs a different format specifier than jlong, which this
>>> fix now defines as 'long'.  This is because, as shown below, the Mac OS
>>> C++ compiler is picky about format specifiers for values of types 'long
>>> long' and 'long'.
>>>     $ gcc lld.cpp
>>>     lld.cpp: In function int main(int, char**):
>>>     lld.cpp:8: warning: format %lld expects type long long int, but
>>>     argument 2 has type long int
>>>     lld.cpp:9: warning: format %ld expects type long int, but 
>>> argument 2
>>>     has type int64_t
>>>     $ cat lld.cpp
>>>     #include <stdio.h>
>>>     #include <stdint.h>
>>>     int main(int argc, char * argv[]) {
>>>        long long_val = 5;
>>>        int64_t int64_val = 8;
>>>        printf("long_val: %ld\n", long_val);
>>>        printf("long_val: %lld\n", long_val); <---- Line 8
>>>        printf("int64_val: %ld\n", int64_val); <--- Line 9
>>>        printf("int64_val: %lld\n", int64_val);
>>>        return 0;
>>>     }
>>> That is why I added JLONG_FORMAT.
>>> Thanks, Harold
>>> On 1/10/2013 9:46 PM, Vladimir Kozlov wrote:
>>>> Can we just define INT64_FORMAT as platform specific and use it
>>>> instead of adding new JLONG_FORMAT?
>>>> Thanks,
>>>> Vladimir
>>>> On 1/10/13 10:39 AM, harold seigel wrote:
>>>>> Hi,
>>>>> Please review the following changes to fix bug 7102489.
>>>>> Summary:
>>>>> The definition of type jlong differed on Mac OS from the other 64 bit
>>>>> platforms.  This fix makes it consistent.  In order to do this, 
>>>>> this fix
>>>>> defines new macros, JLONG_FORMAT and JULONG_FORMAT, for printing and
>>>>> scanning jlongs and julongs.
>>>>> This fix also does some cleanup.  Methods jlong_format_specifier() 
>>>>> and
>>>>> julong_format_specifer() were removed and some format specifiers were
>>>>> replaced with appropriate macros.
>>>>> Open webrev at
>>>>> <>
>>>>> Bug link at
>>>>> Thank you,
>>>>> Harold
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