Mercurial > hg > truffle
diff src/share/vm/oops/markOop.inline.hpp @ 2038:74ee0db180fa
6807801: CMS: could save/restore fewer header words during scavenge
Summary: Age bits need not enter the mark-word preservation calculus; also affected, in addition to CMS, per CR synopsis above, were ParNew (but not DefNew), ParallelScavenge and G1, albeit to a lesser degree than CMS.
Reviewed-by: tonyp, johnc
author | ysr |
---|---|
date | Fri, 17 Dec 2010 23:41:31 -0800 |
parents | f95d63e2154a |
children | da91efe96a93 |
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--- a/src/share/vm/oops/markOop.inline.hpp Fri Dec 17 11:26:53 2010 -0800 +++ b/src/share/vm/oops/markOop.inline.hpp Fri Dec 17 23:41:31 2010 -0800 @@ -30,7 +30,7 @@ #include "oops/markOop.hpp" #include "runtime/globals.hpp" -// Should this header be preserved during GC? +// Should this header be preserved during GC (when biased locking is enabled)? inline bool markOopDesc::must_be_preserved_with_bias(oop obj_containing_mark) const { assert(UseBiasedLocking, "unexpected"); if (has_bias_pattern()) { @@ -47,14 +47,15 @@ return (!is_unlocked() || !has_no_hash()); } +// Should this header be preserved during GC? inline bool markOopDesc::must_be_preserved(oop obj_containing_mark) const { if (!UseBiasedLocking) return (!is_unlocked() || !has_no_hash()); return must_be_preserved_with_bias(obj_containing_mark); } -// Should this header (including its age bits) be preserved in the -// case of a promotion failure during scavenge? +// Should this header be preserved in the case of a promotion failure +// during scavenge (when biased locking is enabled)? inline bool markOopDesc::must_be_preserved_with_bias_for_promotion_failure(oop obj_containing_mark) const { assert(UseBiasedLocking, "unexpected"); // We don't explicitly save off the mark words of biased and @@ -70,18 +71,20 @@ prototype_for_object(obj_containing_mark)->has_bias_pattern()) { return true; } - return (this != prototype()); + return (!is_unlocked() || !has_no_hash()); } +// Should this header be preserved in the case of a promotion failure +// during scavenge? inline bool markOopDesc::must_be_preserved_for_promotion_failure(oop obj_containing_mark) const { if (!UseBiasedLocking) - return (this != prototype()); + return (!is_unlocked() || !has_no_hash()); return must_be_preserved_with_bias_for_promotion_failure(obj_containing_mark); } -// Should this header (including its age bits) be preserved in the -// case of a scavenge in which CMS is the old generation? +// Same as must_be_preserved_with_bias_for_promotion_failure() except that +// it takes a klassOop argument, instead of the object of which this is the mark word. inline bool markOopDesc::must_be_preserved_with_bias_for_cms_scavenge(klassOop klass_of_obj_containing_mark) const { assert(UseBiasedLocking, "unexpected"); // CMS scavenges preserve mark words in similar fashion to promotion failures; see above @@ -89,11 +92,14 @@ klass_of_obj_containing_mark->klass_part()->prototype_header()->has_bias_pattern()) { return true; } - return (this != prototype()); + return (!is_unlocked() || !has_no_hash()); } + +// Same as must_be_preserved_for_promotion_failure() except that +// it takes a klassOop argument, instead of the object of which this is the mark word. inline bool markOopDesc::must_be_preserved_for_cms_scavenge(klassOop klass_of_obj_containing_mark) const { if (!UseBiasedLocking) - return (this != prototype()); + return (!is_unlocked() || !has_no_hash()); return must_be_preserved_with_bias_for_cms_scavenge(klass_of_obj_containing_mark); }