RFR: 8022899: SunStudio compiler can not handle EXCEPTION_MARK and inlining

[Erik Helin]

Coleen and Mikael,

thanks for reviewing!

Erik

On 2013-08-14, Mikael Gerdin wrote:
> Erik,
> 
> I agree with Coleen, I think this change is a good work-around.
> 
> /Mikael
> 
> 
> On 2013-08-13 19:34, Coleen Phillimore wrote:
> >
> >This change is fine.   The side effect of assigning THREAD from
> >EXCEPTION_MARK is something the code uses a lot, so it probably
> >shouldn't be changed.
> >
> >redefining the macro to be:
> >
> >#define EXCEPTION_MARK  Thread* THREAD = Thread::current();
> >ExceptionMark em(THREAD);
> >
> >would enable removing the non-const reference to ExceptionMark
> >constructor but it might draw in thread.inline.hpp dependencies to
> >exceptions.hpp, which would be bad.
> >
> >So I think your change is fine.
> >
> >Coleen
> >
> >On 08/13/2013 10:45 AM, Erik Helin wrote:
> >>Hi all,
> >>
> >>this change initializes the Thread* in the EXCEPTION_MARK macro in
> >>utilities/exception.hpp to NULL to avoid incorrect warnings from the Sun
> >>Studio 12u1 compiler.
> >>
> >>Background:
> >>HotSpot's exception handling code make use of the EXCEPTION_MARK macro
> >>defined in utilities/exception.hpp:
> >>
> >>   #define EXCEPTION_MARK Thread* THREAD; ExceptionMark __em(THREAD);
> >>
> >>where THREAD is defined in the same file as:
> >>
> >>   #define THREAD __the_thread__
> >>
> >>The constructor for the class ExceptionMark takes a reference to Thread
> >>pointer and assigns it:
> >>
> >>   ExceptionMark::ExceptionMark(Thread*& thread) {
> >>     thread = Thread::current();
> >>     // see utilities/exceptions.cpp for the rest
> >>   }
> >>
> >>This means that the Thread pointer __the_thread__ from the
> >>EXCEPTION_MARK macro will be initialized by the ExceptionMark
> >>constructor (since it takes a pointer reference as argument).
> >>
> >>However, the Sun Studio compiler sometimes gives a warning that the
> >>Thread pointer __the_thread__ is uninitialized. The following code is an
> >>example:
> >>
> >>memory/example.cpp:
> >>   static void print_str(const char* s, TRAPS) { // TRAPS is defined as:
> >>     tty->print_cr(s);                           // #define TRAPS
> >>Thread* THREAD
> >>   }                                             // in
> >>utilities/exception.hpp
> >>
> >>   static inline void example(const char* s) {
> >>     EXCEPTION_MARK;
> >>
> >>     print_str(s, THREAD); // line 36
> >>   }
> >>
> >>   void run_example() {
> >>     example("This will not compile");
> >>   }
> >>
> >>memory/example.hpp:
> >>   void run_example();
> >>
> >>memory/universe.cpp:
> >>   // include "runtime/example.hpp"
> >>   // add a call to run_example() in universe_post_init
> >>
> >>Compiling this with Sun Studio 12u1 will (incorrectly) result in the
> >>warning:
> >>src/share/vm/memory/example.cpp", line 36:
> >>Warning: The variable __the_thread__ has not yet been assigned a value.
> >>
> >>Removing the "inline" keyword from "static inline void example" makes
> >>the code compiler without warnings.
> >>
> >>Solution:
> >>Change the EXCEPTION_MARK macro to:
> >>
> >>   #define EXCEPTION_MARK Thread* THREAD = NULL; ExceptionMark
> >>__em(THREAD);
> >>
> >>Webrev:
> >>http://cr.openjdk.java.net/~ehelin/8022899/webrev.00/
> >>
> >>Testing:
> >>- JPRT
> >>- Compiling the example described above successfully
> >>
> >>Bug:
> >>http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8022899
> >>
> >>Thanks,
> >>Erik
> >