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src/share/vm/memory/universe.cpp
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rev 7602 : 8064457: Introduce compressed oops mode disjoint base and improve compressed heap handling.
*** 692,798 ****
// NarrowOopHeapBaseMin + heap_size < 4Gb
// ZeroBased - Use zero based compressed oops with encoding when
// NarrowOopHeapBaseMin + heap_size < 32Gb
// HeapBased - Use compressed oops with heap base + encoding.
- // 4Gb
- static const uint64_t UnscaledOopHeapMax = (uint64_t(max_juint) + 1);
- // 32Gb
- // OopEncodingHeapMax == UnscaledOopHeapMax << LogMinObjAlignmentInBytes;
-
- char* Universe::preferred_heap_base(size_t heap_size, size_t alignment, NARROW_OOP_MODE mode) {
- assert(is_size_aligned((size_t)OopEncodingHeapMax, alignment), "Must be");
- assert(is_size_aligned((size_t)UnscaledOopHeapMax, alignment), "Must be");
- assert(is_size_aligned(heap_size, alignment), "Must be");
-
- uintx heap_base_min_address_aligned = align_size_up(HeapBaseMinAddress, alignment);
-
- 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 + heap_base_min_address_aligned;
- // Return specified base for the first request.
- if (!FLAG_IS_DEFAULT(HeapBaseMinAddress) && (mode == UnscaledNarrowOop)) {
- base = heap_base_min_address_aligned;
-
- // If the total size is small enough to allow UnscaledNarrowOop then
- // just use UnscaledNarrowOop.
- } else if ((total_size <= OopEncodingHeapMax) && (mode != HeapBasedNarrowOop)) {
- if ((total_size <= UnscaledOopHeapMax) && (mode == UnscaledNarrowOop) &&
- (Universe::narrow_oop_shift() == 0)) {
- // Use 32-bits oops without encoding and
- // place heap's top on the 4Gb boundary
- base = (UnscaledOopHeapMax - heap_size);
- } else {
- // Can't reserve with NarrowOopShift == 0
- Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
-
- if (mode == UnscaledNarrowOop ||
- mode == ZeroBasedNarrowOop && total_size <= UnscaledOopHeapMax) {
-
- // 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.
- uint64_t heap_top = OopEncodingHeapMax;
-
- // For small heaps, save some space for compressed class pointer
- // space so it can be decoded with no base.
- if (UseCompressedClassPointers && !UseSharedSpaces &&
- OopEncodingHeapMax <= 32*G) {
-
- uint64_t class_space = align_size_up(CompressedClassSpaceSize, alignment);
- assert(is_size_aligned((size_t)OopEncodingHeapMax-class_space,
- alignment), "difference must be aligned too");
- uint64_t new_top = OopEncodingHeapMax-class_space;
-
- if (total_size <= new_top) {
- heap_top = new_top;
- }
- }
-
- // Align base to the adjusted top of the heap
- base = heap_top - heap_size;
- }
- }
- } else {
- // UnscaledNarrowOop encoding didn't work, and no base was found for ZeroBasedOops or
- // HeapBasedNarrowOop encoding was requested. So, 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)UnscaledOopHeapMax);
- #if defined(_WIN64) || defined(AIX)
- 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
-
- assert(is_ptr_aligned((char*)base, alignment), "Must be");
- return (char*)base; // also return NULL (don't care) for 32-bit VM
- }
-
jint Universe::initialize_heap() {
if (UseParallelGC) {
#if INCLUDE_ALL_GCS
Universe::_collectedHeap = new ParallelScavengeHeap();
--- 692,701 ----
*** 842,882 ****
// This also makes implicit null checking work, because the
// memory+1 page below heap_base needs to cause a signal.
// See needs_explicit_null_check.
// Only set the heap base for compressed oops because it indicates
// compressed oops for pstack code.
! if (((uint64_t)Universe::heap()->reserved_region().end() > OopEncodingHeapMax)) {
! // Can't reserve heap below 32Gb.
! // keep the Universe::narrow_oop_base() set in Universe::reserve_heap()
Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
- #ifdef AIX
- // There is no protected page before the heap. This assures all oops
- // are decoded so that NULL is preserved, so this page will not be accessed.
- Universe::set_narrow_oop_use_implicit_null_checks(false);
- #endif
- } else {
- Universe::set_narrow_oop_base(0);
- #ifdef _WIN64
- if (!Universe::narrow_oop_use_implicit_null_checks()) {
- // 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);
- }
- #endif // _WIN64
- if((uint64_t)Universe::heap()->reserved_region().end() > UnscaledOopHeapMax) {
- // Can't reserve heap below 4Gb.
- Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
- } else {
- Universe::set_narrow_oop_shift(0);
}
}
Universe::set_narrow_ptrs_base(Universe::narrow_oop_base());
if (PrintCompressedOopsMode || (PrintMiscellaneous && Verbose)) {
Universe::print_compressed_oops_mode();
}
}
// Universe::narrow_oop_base() is one page below the heap.
assert((intptr_t)Universe::narrow_oop_base() <= (intptr_t)(Universe::heap()->base() -
os::vm_page_size()) ||
Universe::narrow_oop_base() == NULL, "invalid value");
--- 745,773 ----
// This also makes implicit null checking work, because the
// memory+1 page below heap_base needs to cause a signal.
// See needs_explicit_null_check.
// Only set the heap base for compressed oops because it indicates
// compressed oops for pstack code.
! if ((uint64_t)Universe::heap()->reserved_region().end() > UnscaledOopHeapMax) {
! // Didn't reserve heap below 4Gb. Must shift.
Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
}
+ if ((uint64_t)Universe::heap()->reserved_region().end() <= OopEncodingHeapMax) {
+ // Did reserve heap below 32Gb. Can use base == 0;
+ Universe::set_narrow_oop_base(0);
}
Universe::set_narrow_ptrs_base(Universe::narrow_oop_base());
if (PrintCompressedOopsMode || (PrintMiscellaneous && Verbose)) {
Universe::print_compressed_oops_mode();
}
+
+ // Tell tests in which mode we run.
+ Arguments::PropertyList_add(new SystemProperty("java.vm.compressedOopsMode",
+ narrow_oop_mode_to_string(narrow_oop_mode()),
+ false));
}
// Universe::narrow_oop_base() is one page below the heap.
assert((intptr_t)Universe::narrow_oop_base() <= (intptr_t)(Universe::heap()->base() -
os::vm_page_size()) ||
Universe::narrow_oop_base() == NULL, "invalid value");
*** 901,975 ****
Universe::heap()->base(), Universe::heap()->reserved_region().byte_size()/M);
tty->print(", Compressed Oops mode: %s", narrow_oop_mode_to_string(narrow_oop_mode()));
if (Universe::narrow_oop_base() != 0) {
! tty->print(":" PTR_FORMAT, Universe::narrow_oop_base());
}
if (Universe::narrow_oop_shift() != 0) {
tty->print(", Oop shift amount: %d", Universe::narrow_oop_shift());
}
tty->cr();
tty->cr();
}
- // Reserve the Java heap, which is now the same for all GCs.
ReservedSpace Universe::reserve_heap(size_t heap_size, size_t alignment) {
assert(alignment <= Arguments::conservative_max_heap_alignment(),
err_msg("actual alignment "SIZE_FORMAT" must be within maximum heap alignment "SIZE_FORMAT,
alignment, Arguments::conservative_max_heap_alignment()));
size_t total_reserved = align_size_up(heap_size, alignment);
assert(!UseCompressedOops || (total_reserved <= (OopEncodingHeapMax - os::vm_page_size())),
"heap size is too big for compressed oops");
bool use_large_pages = UseLargePages && is_size_aligned(alignment, os::large_page_size());
assert(!UseLargePages
|| UseParallelGC
|| use_large_pages, "Wrong alignment to use large pages");
! char* addr = Universe::preferred_heap_base(total_reserved, alignment, Universe::UnscaledNarrowOop);
! ReservedHeapSpace total_rs(total_reserved, alignment, use_large_pages, addr);
if (UseCompressedOops) {
! if (addr != NULL && !total_rs.is_reserved()) {
! // Failed to reserve at specified address - the requested memory
! // region is taken already, for example, by 'java' launcher.
! // Try again to reserver heap higher.
! addr = Universe::preferred_heap_base(total_reserved, alignment, Universe::ZeroBasedNarrowOop);
!
! ReservedHeapSpace total_rs0(total_reserved, alignment,
! use_large_pages, addr);
!
! if (addr != NULL && !total_rs0.is_reserved()) {
! // Failed to reserve at specified address again - give up.
! addr = Universe::preferred_heap_base(total_reserved, alignment, Universe::HeapBasedNarrowOop);
! assert(addr == NULL, "");
!
! ReservedHeapSpace total_rs1(total_reserved, alignment,
! use_large_pages, addr);
! total_rs = total_rs1;
! } else {
! total_rs = total_rs0;
! }
! }
}
- if (!total_rs.is_reserved()) {
- vm_exit_during_initialization(err_msg("Could not reserve enough space for " SIZE_FORMAT "KB object heap", total_reserved/K));
return total_rs;
}
! if (UseCompressedOops) {
! // Universe::initialize_heap() will reset this to NULL if unscaled
! // or zero-based narrow oops are actually used.
! address base = (address)(total_rs.base() - os::vm_page_size());
! Universe::set_narrow_oop_base(base);
! }
! return total_rs;
}
// It's the caller's responsibility to ensure glitch-freedom
// (if required).
--- 792,856 ----
Universe::heap()->base(), Universe::heap()->reserved_region().byte_size()/M);
tty->print(", Compressed Oops mode: %s", narrow_oop_mode_to_string(narrow_oop_mode()));
if (Universe::narrow_oop_base() != 0) {
! tty->print(": " PTR_FORMAT, Universe::narrow_oop_base());
}
if (Universe::narrow_oop_shift() != 0) {
tty->print(", Oop shift amount: %d", Universe::narrow_oop_shift());
}
+ if (!Universe::narrow_oop_use_implicit_null_checks()) {
+ tty->print(", no protected page in front of the heap");
+ }
+
tty->cr();
tty->cr();
}
ReservedSpace Universe::reserve_heap(size_t heap_size, size_t alignment) {
+
assert(alignment <= Arguments::conservative_max_heap_alignment(),
err_msg("actual alignment "SIZE_FORMAT" must be within maximum heap alignment "SIZE_FORMAT,
alignment, Arguments::conservative_max_heap_alignment()));
+
size_t total_reserved = align_size_up(heap_size, alignment);
assert(!UseCompressedOops || (total_reserved <= (OopEncodingHeapMax - os::vm_page_size())),
"heap size is too big for compressed oops");
bool use_large_pages = UseLargePages && is_size_aligned(alignment, os::large_page_size());
assert(!UseLargePages
|| UseParallelGC
|| use_large_pages, "Wrong alignment to use large pages");
! // Now create the space.
! ReservedHeapSpace total_rs(total_reserved, alignment, use_large_pages);
! if (total_rs.is_reserved()) {
! assert((total_reserved == total_rs.size()) && ((uintptr_t)total_rs.base() % alignment == 0),
! "must be exactly of required size and alignment");
! // We are good.
if (UseCompressedOops) {
! // Universe::initialize_heap() will reset this to NULL if unscaled
! // or zero-based narrow oops are actually used.
! // Else heap start and base MUST differ, so that NULL can be encoded nonambigous.
! Universe::set_narrow_oop_base((address)total_rs.compressed_oop_base());
}
return total_rs;
}
! vm_exit_during_initialization(
! err_msg("Could not reserve enough space for " SIZE_FORMAT "KB object heap",
! total_reserved/K));
!
! // satisfy compiler
! ShouldNotReachHere();
! return ReservedHeapSpace(0, 0, false);
}
// It's the caller's responsibility to ensure glitch-freedom
// (if required).
*** 983,1002 ****
--- 864,889 ----
switch (mode) {
case UnscaledNarrowOop:
return "32-bit";
case ZeroBasedNarrowOop:
return "Zero based";
+ case DisjointBaseNarrowOop:
+ return "Non-zero disjoint base";
case HeapBasedNarrowOop:
return "Non-zero based";
}
ShouldNotReachHere();
return "";
}
Universe::NARROW_OOP_MODE Universe::narrow_oop_mode() {
+ if (narrow_oop_base_disjoint()) {
+ return DisjointBaseNarrowOop;
+ }
+
if (narrow_oop_base() != 0) {
return HeapBasedNarrowOop;
}
if (narrow_oop_shift() != 0) {
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