[8u60] RFR of backport for 8066875: VirtualSpace does not use large pages

[Thomas Schatzl]

Hi all,

  can I have reviews for the backport of "8066875: VirtualSpace does not
use large pages" for 8u60? I also would like to have one review from the
compiler team (cc'ed) since the change touches some compiler files.

It did only apply with minor changes, so I need re-reviews. The problem
is that in jdk9 the code cache sizing has been changed. In particular:
- dropped the hunk in code/codeCache.cpp because the code to determine
memory sizes in 8u60 is much simpler i.e. .
E.g. this change:
--- a/src/share/vm/code/codeCache.cpp	Thu Jan 15 16:05:20 2015 +0100
+++ b/src/share/vm/code/codeCache.cpp	Fri Jan 16 10:29:12 2015 +0100
@@ -233,8 +233,8 @@
 ReservedCodeSpace CodeCache::reserve_heap_memory(size_t size) {
   // Determine alignment
   const size_t page_size = os::can_execute_large_page_memory() ?
-          MIN2(os::page_size_for_region(InitialCodeCacheSize, 8),
-               os::page_size_for_region(size, 8)) :
+          MIN2(os::page_size_for_region_aligned(InitialCodeCacheSize, 8),
+               os::page_size_for_region_aligned(size, 8)) :
           os::vm_page_size();
   const size_t granularity = os::vm_allocation_granularity();
   const size_t r_align = MAX2(page_size, granularity);

- fixed the code in heap.cpp because of the same change (JDK-8015774:
Add support for multiple code heaps) is not in 8u60.

Note that this change is based on "8049864: TestParallelHeapSizeFlags
fails with unexpected heap size"
which is also out for review (on hotspot-gc-dev), and "8053995: Add
method to WhiteBox to get vm_pagesize" which applies cleanly.

Full 8u60 changeset:
http://cr.openjdk.java.net/~tschatzl/8066875-8u60/webrev.8u60/
Fix changeset:
http://cr.openjdk.java.net/~tschatzl/8066875-8u60/webrev.8u60-fix/

CR:
https://bugs.openjdk.java.net/browse/JDK-8066875
Original change:
http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/4321214d5dbc

Testing: jprt

With that changeset in place, JDK-8058354 can be merged relatively
easily, which is the goal of most of the recent backports.

Thanks,
  Thomas