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6896084: VM does not reserve protected page below heap for compressed oops implicit null checks

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Set narrow_oop_base and narrow_oop_use_implicit_null_checks in Universe::preferred_heap_base().

Reviewed-by: twisti, jcoomes
This commit is contained in:
Vladimir Kozlov 2009-10-29 16:57:55 -07:00
parent c1eacdef5a
commit bdd0f44def
1 changed files with 29 additions and 7 deletions
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36
hotspot/src/share/vm/memory/universe.cpp
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@ -744,22 +744,22 @@ static const uint64_t NarrowOopHeapMax = (uint64_t(max_juint) + 1);
static const uint64_t OopEncodingHeapMax = NarrowOopHeapMax << LogMinObjAlignmentInBytes;
char* Universe::preferred_heap_base(size_t heap_size, NARROW_OOP_MODE mode) {
size_t base = 0;
#ifdef _LP64
if (UseCompressedOops) {
assert(mode == UnscaledNarrowOop ||
mode == ZeroBasedNarrowOop ||
mode == HeapBasedNarrowOop, "mode is invalid");
const size_t total_size = heap_size + HeapBaseMinAddress;
// Return specified base for the first request.
if (!FLAG_IS_DEFAULT(HeapBaseMinAddress) && (mode == UnscaledNarrowOop)) {
return (char*)HeapBaseMinAddress;
}
const size_t total_size = heap_size + HeapBaseMinAddress;
if (total_size <= OopEncodingHeapMax && (mode != HeapBasedNarrowOop)) {
base = HeapBaseMinAddress;
} else if (total_size <= OopEncodingHeapMax && (mode != HeapBasedNarrowOop)) {
if (total_size <= NarrowOopHeapMax && (mode == UnscaledNarrowOop) &&
(Universe::narrow_oop_shift() == 0)) {
// Use 32-bits oops without encoding and
// place heap's top on the 4Gb boundary
return (char*)(NarrowOopHeapMax - heap_size);
base = (NarrowOopHeapMax - heap_size);
} else {
// Can't reserve with NarrowOopShift == 0
Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
@ -768,16 +768,38 @@ char* Universe::preferred_heap_base(size_t heap_size, NARROW_OOP_MODE mode) {
// Use zero based compressed oops with encoding and
// place heap's top on the 32Gb boundary in case
// total_size > 4Gb or failed to reserve below 4Gb.
return (char*)(OopEncodingHeapMax - heap_size);
base = (OopEncodingHeapMax - heap_size);
}
}
} else {
// Can't reserve below 32Gb.
Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
}
// Set narrow_oop_base and narrow_oop_use_implicit_null_checks
// used in ReservedHeapSpace() constructors.
// The final values will be set in initialize_heap() below.
if (base != 0 && (base + heap_size) <= OopEncodingHeapMax) {
// Use zero based compressed oops
Universe::set_narrow_oop_base(NULL);
// Don't need guard page for implicit checks in indexed
// addressing mode with zero based Compressed Oops.
Universe::set_narrow_oop_use_implicit_null_checks(true);
} else {
// Set to a non-NULL value so the ReservedSpace ctor computes
// the correct no-access prefix.
// The final value will be set in initialize_heap() below.
Universe::set_narrow_oop_base((address)NarrowOopHeapMax);
#ifdef _WIN64
if (UseLargePages) {
// Cannot allocate guard pages for implicit checks in indexed
// addressing mode when large pages are specified on windows.
Universe::set_narrow_oop_use_implicit_null_checks(false);
}
#endif // _WIN64
}
}
#endif
return NULL; // also return NULL (don't care) for 32-bit VM
return (char*)base; // also return NULL (don't care) for 32-bit VM
}
jint Universe::initialize_heap() {