RFR JDK-8022407 sun/misc/CopyMemory.java fails with SIGSEGV in Unsafe_SetByte+0x35

[Coleen Phillimore]

On 08/27/2013 03:39 PM, Lois Foltan wrote:
>
> On 8/27/2013 1:29 PM, Christian Thalinger wrote:
>> On Aug 27, 2013, at 9:18 AM, Lois Foltan <lois.foltan at oracle.com> wrote:
>>
>>> Please review the following fix:
>>>     open webrev at http://cr.openjdk.java.net/~hseigel/bug_jdk8022407/
>>>
>>> Bug:
>>>     bug link at https://bugs.openjdk.java.net/browse/JDK-8022407
>>>
>>> Summary of fix:
>>>
>>> The JDK 8 build on MacOS, when built with the Xcode 4.6.2 clang++ 
>>> compiler, exhibited a compiler optimization issue when 
>>> prims/unsafe.cpp was compiled at the default -Os level. As a work 
>>> around fix, knock the optimization level down down to -O0.
>> Why are we lowering to -O0 when you state in the bug report that -O1 
>> also works?  What is the code that breaks?
>>
>> -- Chris
> Hi Chris,
> The convention within make/bsd/makefiles/gcc.make indicated that 
> historically files that exhibited C++ compiler optimization issues 
> were knocked down to /NOOPT or -O0.  I did also check with Coleen to 
> make sure that prims/unsafe.cpp was not a performance critical file. 

So my advice was that it wasn't performance critical - because it's 
mostly calls from Java.  Except for maybe the anonymous class 
functions.  If you disagree, let us know.

Coleen

> -O1 does add some optimizations on top of -O0 but not inlining.  I 
> will recheck testing with -O1 to confirm and change unsafe.cpp's 
> optimization level to -O1 if testing yields good results.
>
> I suspect the optimization problem is in unsafe.cpp's definition of 
> Unsafe_GetNativeByte.  I had left off tracking it at that level and 
> certainly will not close the JDK bug until I can narrow in further and 
> hopefully report to the clang compiler team.
>
> Thanks,
> Lois
>>> Tests:
>>>     MacOS: built fastdebug & product images using clang++ (ran JTREG 
>>> & vm.quick.testlist)
>>>                    built using llvm-g++ to verify prims/unsafe.cpp 
>>> remained compiled at -Os
>>>
>>> Thank you,
>>> Lois
>>>
>>>
>