Use leftmost region in GC allocations

[Aleksey Shipilev]

On 02/06/2018 08:05 PM, Dominik Inführ wrote:
> Hi,
> 
> allocate_single in ShenandoahFreeSet doesn't use the leftmost-Region. Quite
> a minor problem but it might be worth to fix.
> 
> diff --git a/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp
> b/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp
> --- a/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp
> +++ b/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp
> @@ -72,9 +72,9 @@
>      }
>      case ShenandoahHeap::_alloc_gclab:
>      case ShenandoahHeap::_alloc_shared_gc: {
> -      for (size_t idx = _rightmost; idx > _leftmost; idx--) {
> -        if (is_free(idx)) {
> -          HeapWord* result = try_allocate_in(word_size, type, idx,
> in_new_region);
> +      for (size_t idx = _rightmost + 1; idx > _leftmost; idx--) {
> +        if (is_free(idx - 1)) {
> +          HeapWord* result = try_allocate_in(word_size, type, idx - 1,
> in_new_region);
>            if (result != NULL) {
>              return result;
>            }

Right.

But isn't this just:

$ hg diff
diff -r a95aa48e56ed src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp	Tue Feb 06 20:57:54 2018 +0100
+++ b/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp	Tue Feb 06 21:00:13 2018 +0100
@@ -72,7 +72,7 @@
     }
     case ShenandoahHeap::_alloc_gclab:
     case ShenandoahHeap::_alloc_shared_gc: {
-      for (size_t idx = _rightmost; idx > _leftmost; idx--) {
+      for (size_t idx = _rightmost; idx >= _leftmost; idx--) {
         if (is_free(idx)) {
           HeapWord* result = try_allocate_in(word_size, type, idx, in_new_region);
           if (result != NULL) {

?

-Aleksey