RFR (S): 8143215: gcc 4.1.2: fix three issues breaking the build.

[Kim Barrett]

On Dec 11, 2015, at 5:52 AM, Lindenmaier, Goetz <goetz.lindenmaier at sap.com> wrote:
> 
> diff -r 73e267ddd93d src/share/vm/gc/cms/concurrentMarkSweepGeneration.cpp
> --- a/src/share/vm/gc/cms/concurrentMarkSweepGeneration.cpp     Wed Nov 18 11:31:59 2015 +0100
> +++ b/src/share/vm/gc/cms/concurrentMarkSweepGeneration.cpp     Fri Dec 11 11:42:52 2015 +0100
> @@ -2731,7 +2731,7 @@
>   // Not MT-safe; so do not pass around these StackObj's
>   // where they may be accessed by other threads.
>   jlong wallclock_millis() {
> -    return TimeHelper::counter_to_millis(os::elapsed_counter() - _trace_time.start_time());
> +    return (jlong)TimeHelper::counter_to_millis(os::elapsed_counter() - _trace_time.start_time());
>   }
> };

This conversion was introduced by the recently pushed 8145092: Use Unified Logging for the GC logging.

The only caller of wallclock_millis compares the result with CMSMaxAbortablePrecleanTime (an intx).

So I think we’ve always had a bit of a type mismatch here.

I’m not sure what to do about this one yet, but adding a cast doesn’t seem like the right solution to me.

> diff -r 73e267ddd93d src/share/vm/gc/g1/g1CollectedHeap.cpp
> --- a/src/share/vm/gc/g1/g1CollectedHeap.cpp    Wed Nov 18 11:31:59 2015 +0100
> +++ b/src/share/vm/gc/g1/g1CollectedHeap.cpp    Fri Dec 11 11:42:52 2015 +0100
> @@ -3621,7 +3621,7 @@
>     log_info(gc)("To-space exhausted");
>   }
> 
> -  double pause_time_sec = TimeHelper::counter_to_seconds(pause_time_counter);
> +  double pause_time_sec = TimeHelper::counter_to_seconds((jlong)pause_time_counter);
>   g1_policy()->print_phases(pause_time_sec);
> 
>   g1_policy()->print_detailed_heap_transition();

Adding a cast is not the proper fix here.

The problem is that log_gc_footer’s double pause_time_counter argument ought to itself be a jlong.
The caller (do_collection_pause_at_safepoint) contains

  double pause_start_counter = os::elapsed_counter();
  …
  log_gc_footer(os::elapsed_counter() - pause_start_counter);

elapsed_counter returns a jlong.  So pause_start_counter ought to be a jlong too, and fixing the
parameter type for log_gc_footer would then make everything work out.

This appears to be a mistake introduced by the recently pushed 8145092: Use Unified Logging for the GC logging.