On 8/27/2013 1:29 PM, Christian Thalinger wrote:
On Aug 27, 2013, at 9:18 AM, Lois Foltan <lois.fol...@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. -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
