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6716785: implicit null checks not triggering with CompressedOops

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Allocate alignment-sized page(s) below java heap so that memory accesses at heap_base+1page give signal and cause an implicit null check

Reviewed-by: kvn, jmasa, phh, jcoomes
This commit is contained in:
Coleen Phillimore 2008-07-19 17:38:22 -04:00
parent 575988272e
commit 20dba03e99
23 changed files with 197 additions and 133 deletions
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26
hotspot/src/share/vm/runtime/virtualspace.hpp
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@ -29,13 +29,15 @@ class ReservedSpace VALUE_OBJ_CLASS_SPEC {
private:
char* _base;
size_t _size;
size_t _noaccess_prefix;
size_t _alignment;
bool _special;
// ReservedSpace
ReservedSpace(char* base, size_t size, size_t alignment, bool special);
void initialize(size_t size, size_t alignment, bool large,
char* requested_address = NULL);
char* requested_address,
const size_t noaccess_prefix);
// Release parts of an already-reserved memory region [addr, addr + len) to
// get a new region that has "compound alignment." Return the start of the
@ -59,13 +61,19 @@ class ReservedSpace VALUE_OBJ_CLASS_SPEC {
const size_t suffix_size,
const size_t suffix_align);
protected:
// Create protection page at the beginning of the space.
void protect_noaccess_prefix(const size_t size);
public:
// Constructor
ReservedSpace(size_t size);
ReservedSpace(size_t size, size_t alignment, bool large,
char* requested_address = NULL);
char* requested_address = NULL,
const size_t noaccess_prefix = 0);
ReservedSpace(const size_t prefix_size, const size_t prefix_align,
const size_t suffix_size, const size_t suffix_align);
const size_t suffix_size, const size_t suffix_align,
const size_t noaccess_prefix);
// Accessors
char* base() const { return _base; }
@ -73,6 +81,8 @@ class ReservedSpace VALUE_OBJ_CLASS_SPEC {
size_t alignment() const { return _alignment; }
bool special() const { return _special; }
size_t noaccess_prefix() const { return _noaccess_prefix; }
bool is_reserved() const { return _base != NULL; }
void release();
@ -104,6 +114,16 @@ ReservedSpace ReservedSpace::last_part(size_t partition_size)
return last_part(partition_size, alignment());
}
// Class encapsulating behavior specific of memory space reserved for Java heap
class ReservedHeapSpace : public ReservedSpace {
public:
// Constructor
ReservedHeapSpace(size_t size, size_t forced_base_alignment,
bool large, char* requested_address);
ReservedHeapSpace(const size_t prefix_size, const size_t prefix_align,
const size_t suffix_size, const size_t suffix_align);
};
// VirtualSpace is data structure for committing a previously reserved address range in smaller chunks.
class VirtualSpace VALUE_OBJ_CLASS_SPEC {