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src/share/vm/memory/barrierSet.inline.hpp@2c022e432e10 (annotated)

src/share/vm/memory/barrierSet.inline.hpp

Fri, 20 Sep 2013 10:53:28 +0200

author

stefank

date

Fri, 20 Sep 2013 10:53:28 +0200

changeset 5769

2c022e432e10

parent 2314

f95d63e2154a

child 6493

3205e78d8193

permissions

-rw-r--r--

8024974: Incorrect use of GC_locker::is_active()
Summary: SymbolTable and StringTable can make calls to GC_locker::is_active() outside a safepoint. This isn't safe because the GC_locker active state (lock count) is only updated at a safepoint and only remains valid as long as _needs_gc is true. However, outside a safepoint_needs_gc can change to false at any time, which makes it impossible to do a correct call to is_active() in that context. In this case these calls can just be removed since the input argument to basic_add() should never be on the heap and so there's no need to check the GC_locker state. This change also adjusts the assert() in is_active() to makes sure all calls to this function are always done under a safepoint.
Reviewed-by: brutisso, dcubed
Contributed-by: per.liden@oracle.com

duke@435	1	/*
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duke@435	24
stefank@2314	25	#ifndef SHARE_VM_MEMORY_BARRIERSET_INLINE_HPP
stefank@2314	26	#define SHARE_VM_MEMORY_BARRIERSET_INLINE_HPP
stefank@2314	27
stefank@2314	28	#include "memory/barrierSet.hpp"
stefank@2314	29	#include "memory/cardTableModRefBS.hpp"
stefank@2314	30
duke@435	31	// Inline functions of BarrierSet, which de-virtualize certain
ysr@1280	32	// performance-critical calls when the barrier is the most common
duke@435	33	// card-table kind.
duke@435	34
ysr@1280	35	template <class T> void BarrierSet::write_ref_field_pre(T* field, oop new_val) {
ysr@777	36	if (kind() == CardTableModRef) {
ysr@777	37	((CardTableModRefBS*)this)->inline_write_ref_field_pre(field, new_val);
ysr@777	38	} else {
ysr@777	39	write_ref_field_pre_work(field, new_val);
ysr@777	40	}
ysr@777	41	}
ysr@777	42
coleenp@548	43	void BarrierSet::write_ref_field(void* field, oop new_val) {
duke@435	44	if (kind() == CardTableModRef) {
duke@435	45	((CardTableModRefBS*)this)->inline_write_ref_field(field, new_val);
duke@435	46	} else {
duke@435	47	write_ref_field_work(field, new_val);
duke@435	48	}
duke@435	49	}
duke@435	50
ysr@1526	51	// count is number of array elements being written
ysr@1526	52	void BarrierSet::write_ref_array(HeapWord* start, size_t count) {
ysr@1526	53	assert(count <= (size_t)max_intx, "count too large");
ysr@1526	54	HeapWord* end = (HeapWord*)((char*)start + (count*heapOopSize));
ysr@1526	55	// In the case of compressed oops, start and end may potentially be misaligned;
ysr@1526	56	// so we need to conservatively align the first downward (this is not
ysr@1526	57	// strictly necessary for current uses, but a case of good hygiene and,
ysr@1526	58	// if you will, aesthetics) and the second upward (this is essential for
ysr@1526	59	// current uses) to a HeapWord boundary, so we mark all cards overlapping
ysr@1680	60	// this write. If this evolves in the future to calling a
ysr@1526	61	// logging barrier of narrow oop granularity, like the pre-barrier for G1
ysr@1526	62	// (mentioned here merely by way of example), we will need to change this
ysr@1680	63	// interface, so it is "exactly precise" (if i may be allowed the adverbial
ysr@1680	64	// redundancy for emphasis) and does not include narrow oop slots not
ysr@1680	65	// included in the original write interval.
ysr@1526	66	HeapWord* aligned_start = (HeapWord*)align_size_down((uintptr_t)start, HeapWordSize);
ysr@1526	67	HeapWord* aligned_end = (HeapWord*)align_size_up ((uintptr_t)end, HeapWordSize);
ysr@1526	68	// If compressed oops were not being used, these should already be aligned
ysr@1526	69	assert(UseCompressedOops || (aligned_start == start && aligned_end == end),
ysr@1526	70	"Expected heap word alignment of start and end");
ysr@1526	71	#if 0
ysr@1526	72	warning("Post:\t" INTPTR_FORMAT "[" SIZE_FORMAT "] : [" INTPTR_FORMAT","INTPTR_FORMAT")\t",
ysr@1526	73	start, count, aligned_start, aligned_end);
ysr@1526	74	#endif
ysr@1526	75	write_ref_array_work(MemRegion(aligned_start, aligned_end));
ysr@1526	76	}
ysr@1526	77
ysr@1526	78
duke@435	79	void BarrierSet::write_region(MemRegion mr) {
duke@435	80	if (kind() == CardTableModRef) {
duke@435	81	((CardTableModRefBS*)this)->inline_write_region(mr);
duke@435	82	} else {
duke@435	83	write_region_work(mr);
duke@435	84	}
duke@435	85	}
stefank@2314	86
stefank@2314	87	#endif // SHARE_VM_MEMORY_BARRIERSET_INLINE_HPP