RFR: 8150720: Cleanup code around PrintOptoStatistics

[Vladimir Kozlov]

Good changes. We indeed print statistics only in non-product build.

graphKit.cpp - add {} to code:

+#ifndef PRODUCT
      if (null_true == top())
        explicit_null_checks_elided++;
+#endif

ifnode.cpp - add {} and adjust spaces "if (dist > 2) {":

+#ifndef PRODUCT
    if( dist > 2 )              // Add to count of NULL checks elided
      explicit_null_checks_elided++;
+#endif

parse1.cpp - the same:

-  if( implicit_null_throws )
+  if( SharedRuntime::_implicit_null_throws )
      tty->print_cr("%d implicit null exceptions at runtime",
-                  implicit_null_throws);
+                  SharedRuntime::_implicit_null_throws);


 > There is also a small "leak" in the corner case where "edge_end ==
 > (char*)this" since we're not freeing the input array in this case.

There is no "leak" since after compilation is done all C2 arenas are 
cleaned/freed. Yes, during compilation required space could be increased.

 > We are not freeing when ASSERT is not defined? O_o The patch that
 > apparently does an equivalent transformation of the original code 
makes it even creepier.

It is done to catch dangling Node* pointers in debug build:

  661 #ifdef ASSERT
  662   // We will not actually delete the storage, but we'll make the 
node unusable.
  663   *(address*)this = badAddress;  // smash the C++ vtbl, probably
  664   _in = _out = (Node**) badAddress;

So please revert that code back except the code which just increment 
unused counters and can be indeed removed.

Thanks,
Vladimir

On 2/26/16 3:40 AM, Claes Redestad wrote:
> Hi,
>
> src/share/vm/opto/parse1.cpp currently defines a number of global
> counters that is used to collect some statistics. Some of these counters
> are incremented in product builds, but ever only displayed in
> non-product builds if run with -XX:+PrintOptoStatistics.
>
> This patch masks such counters from product builds, removes a few
> counters that were never read, fixes an issue with implicit_null_throws
> which was never incremented in current code (seems it was moved to
> SharedRuntime a long time ago without updating print_statistics) and
> removes an unused enum (InlineStyle):
>
> webrev: http://cr.openjdk.java.net/~redestad/8150720/webrev.00/
> bug: https://bugs.openjdk.java.net/browse/JDK-8150720
>
> Testing: RBT --test hotspot/test/:hotspot_all, manual verification that
> -XX:+PrintOptoStatistics prints out a count for implicit NPE's thrown
>
> Thanks!
>
> /Claes