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8135078: Refactor InCSetState::is_in_cset_or_humongous

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Reviewed-by: tschatzl, jwilhelm
This commit is contained in:
Erik Helin 2015-10-19 15:21:01 +02:00
parent 65e88c8313
commit e76add1886
1 changed files with 6 additions and 9 deletions
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15
hotspot/src/share/vm/gc/g1/g1InCSetState.hpp
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@ -51,15 +51,11 @@ struct InCSetState {
enum {
// Selection of the values were driven to micro-optimize the encoding and
// frequency of the checks.
// The most common check is whether the region is in the collection set or not.
// This encoding allows us to use an != 0 check which in some architectures
// (x86*) can be encoded slightly more efficently than a normal comparison
// against zero.
// The same situation occurs when checking whether the region is humongous
// or not, which is encoded by values < 0.
// The most common check is whether the region is in the collection set or not,
// this encoding allows us to use an > 0 check.
// The other values are simply encoded in increasing generation order, which
// makes getting the next generation fast by a simple increment.
Humongous = -1, // The region is humongous - note that actually any value < 0 would be possible here.
Humongous = -1, // The region is humongous
NotInCSet = 0, // The region is not in the collection set.
Young = 1, // The region is in the collection set and a young region.
Old = 2, // The region is in the collection set and an old region.
@ -74,9 +70,10 @@ struct InCSetState {
void set_old() { _value = Old; }
bool is_in_cset_or_humongous() const { return _value != NotInCSet; }
bool is_in_cset_or_humongous() const { return is_in_cset() || is_humongous(); }
bool is_in_cset() const { return _value > NotInCSet; }
bool is_humongous() const { return _value < NotInCSet; }
bool is_humongous() const { return _value == Humongous; }
bool is_young() const { return _value == Young; }
bool is_old() const { return _value == Old; }