duke@435: /*
duke@435:  * Copyright 1997-2005 Sun Microsystems, Inc.  All Rights Reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
duke@435:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435:  * CA 95054 USA or visit www.sun.com if you need additional information or
duke@435:  * have any questions.
duke@435:  *
duke@435:  */
duke@435: 
duke@435: #include "incls/_precompiled.incl"
duke@435: #include "incls/_virtualspace.cpp.incl"
duke@435: 
duke@435: 
duke@435: // ReservedSpace
duke@435: ReservedSpace::ReservedSpace(size_t size) {
duke@435:   initialize(size, 0, false, NULL);
duke@435: }
duke@435: 
duke@435: ReservedSpace::ReservedSpace(size_t size, size_t alignment,
duke@435:                              bool large, char* requested_address) {
duke@435:   initialize(size, alignment, large, requested_address);
duke@435: }
duke@435: 
duke@435: char *
duke@435: ReservedSpace::align_reserved_region(char* addr, const size_t len,
duke@435:                                      const size_t prefix_size,
duke@435:                                      const size_t prefix_align,
duke@435:                                      const size_t suffix_size,
duke@435:                                      const size_t suffix_align)
duke@435: {
duke@435:   assert(addr != NULL, "sanity");
duke@435:   const size_t required_size = prefix_size + suffix_size;
duke@435:   assert(len >= required_size, "len too small");
duke@435: 
duke@435:   const size_t s = size_t(addr);
duke@435:   const size_t beg_ofs = s + prefix_size & suffix_align - 1;
duke@435:   const size_t beg_delta = beg_ofs == 0 ? 0 : suffix_align - beg_ofs;
duke@435: 
duke@435:   if (len < beg_delta + required_size) {
duke@435:      return NULL; // Cannot do proper alignment.
duke@435:   }
duke@435:   const size_t end_delta = len - (beg_delta + required_size);
duke@435: 
duke@435:   if (beg_delta != 0) {
duke@435:     os::release_memory(addr, beg_delta);
duke@435:   }
duke@435: 
duke@435:   if (end_delta != 0) {
duke@435:     char* release_addr = (char*) (s + beg_delta + required_size);
duke@435:     os::release_memory(release_addr, end_delta);
duke@435:   }
duke@435: 
duke@435:   return (char*) (s + beg_delta);
duke@435: }
duke@435: 
duke@435: char* ReservedSpace::reserve_and_align(const size_t reserve_size,
duke@435:                                        const size_t prefix_size,
duke@435:                                        const size_t prefix_align,
duke@435:                                        const size_t suffix_size,
duke@435:                                        const size_t suffix_align)
duke@435: {
duke@435:   assert(reserve_size > prefix_size + suffix_size, "should not be here");
duke@435: 
duke@435:   char* raw_addr = os::reserve_memory(reserve_size, NULL, prefix_align);
duke@435:   if (raw_addr == NULL) return NULL;
duke@435: 
duke@435:   char* result = align_reserved_region(raw_addr, reserve_size, prefix_size,
duke@435:                                        prefix_align, suffix_size,
duke@435:                                        suffix_align);
duke@435:   if (result == NULL && !os::release_memory(raw_addr, reserve_size)) {
duke@435:     fatal("os::release_memory failed");
duke@435:   }
duke@435: 
duke@435: #ifdef ASSERT
duke@435:   if (result != NULL) {
duke@435:     const size_t raw = size_t(raw_addr);
duke@435:     const size_t res = size_t(result);
duke@435:     assert(res >= raw, "alignment decreased start addr");
duke@435:     assert(res + prefix_size + suffix_size <= raw + reserve_size,
duke@435:            "alignment increased end addr");
duke@435:     assert((res & prefix_align - 1) == 0, "bad alignment of prefix");
duke@435:     assert((res + prefix_size & suffix_align - 1) == 0,
duke@435:            "bad alignment of suffix");
duke@435:   }
duke@435: #endif
duke@435: 
duke@435:   return result;
duke@435: }
duke@435: 
duke@435: ReservedSpace::ReservedSpace(const size_t prefix_size,
duke@435:                              const size_t prefix_align,
duke@435:                              const size_t suffix_size,
duke@435:                              const size_t suffix_align)
duke@435: {
duke@435:   assert(prefix_size != 0, "sanity");
duke@435:   assert(prefix_align != 0, "sanity");
duke@435:   assert(suffix_size != 0, "sanity");
duke@435:   assert(suffix_align != 0, "sanity");
duke@435:   assert((prefix_size & prefix_align - 1) == 0,
duke@435:     "prefix_size not divisible by prefix_align");
duke@435:   assert((suffix_size & suffix_align - 1) == 0,
duke@435:     "suffix_size not divisible by suffix_align");
duke@435:   assert((suffix_align & prefix_align - 1) == 0,
duke@435:     "suffix_align not divisible by prefix_align");
duke@435: 
duke@435:   // On systems where the entire region has to be reserved and committed up
duke@435:   // front, the compound alignment normally done by this method is unnecessary.
duke@435:   const bool try_reserve_special = UseLargePages &&
duke@435:     prefix_align == os::large_page_size();
duke@435:   if (!os::can_commit_large_page_memory() && try_reserve_special) {
duke@435:     initialize(prefix_size + suffix_size, prefix_align, true);
duke@435:     return;
duke@435:   }
duke@435: 
duke@435:   _base = NULL;
duke@435:   _size = 0;
duke@435:   _alignment = 0;
duke@435:   _special = false;
duke@435: 
duke@435:   // Optimistically try to reserve the exact size needed.
duke@435:   const size_t size = prefix_size + suffix_size;
duke@435:   char* addr = os::reserve_memory(size, NULL, prefix_align);
duke@435:   if (addr == NULL) return;
duke@435: 
duke@435:   // Check whether the result has the needed alignment (unlikely unless
duke@435:   // prefix_align == suffix_align).
duke@435:   const size_t ofs = size_t(addr) + prefix_size & suffix_align - 1;
duke@435:   if (ofs != 0) {
duke@435:     // Wrong alignment.  Release, allocate more space and do manual alignment.
duke@435:     //
duke@435:     // On most operating systems, another allocation with a somewhat larger size
duke@435:     // will return an address "close to" that of the previous allocation.  The
duke@435:     // result is often the same address (if the kernel hands out virtual
duke@435:     // addresses from low to high), or an address that is offset by the increase
duke@435:     // in size.  Exploit that to minimize the amount of extra space requested.
duke@435:     if (!os::release_memory(addr, size)) {
duke@435:       fatal("os::release_memory failed");
duke@435:     }
duke@435: 
duke@435:     const size_t extra = MAX2(ofs, suffix_align - ofs);
duke@435:     addr = reserve_and_align(size + extra, prefix_size, prefix_align,
duke@435:                              suffix_size, suffix_align);
duke@435:     if (addr == NULL) {
duke@435:       // Try an even larger region.  If this fails, address space is exhausted.
duke@435:       addr = reserve_and_align(size + suffix_align, prefix_size,
duke@435:                                prefix_align, suffix_size, suffix_align);
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   _base = addr;
duke@435:   _size = size;
duke@435:   _alignment = prefix_align;
duke@435: }
duke@435: 
duke@435: void ReservedSpace::initialize(size_t size, size_t alignment, bool large,
duke@435:                                char* requested_address) {
duke@435:   const size_t granularity = os::vm_allocation_granularity();
duke@435:   assert((size & granularity - 1) == 0,
duke@435:          "size not aligned to os::vm_allocation_granularity()");
duke@435:   assert((alignment & granularity - 1) == 0,
duke@435:          "alignment not aligned to os::vm_allocation_granularity()");
duke@435:   assert(alignment == 0 || is_power_of_2((intptr_t)alignment),
duke@435:          "not a power of 2");
duke@435: 
duke@435:   _base = NULL;
duke@435:   _size = 0;
duke@435:   _special = false;
duke@435:   _alignment = 0;
duke@435:   if (size == 0) {
duke@435:     return;
duke@435:   }
duke@435: 
duke@435:   // If OS doesn't support demand paging for large page memory, we need
duke@435:   // to use reserve_memory_special() to reserve and pin the entire region.
duke@435:   bool special = large && !os::can_commit_large_page_memory();
duke@435:   char* base = NULL;
duke@435: 
duke@435:   if (special) {
duke@435:     // It's not hard to implement reserve_memory_special() such that it can
duke@435:     // allocate at fixed address, but there seems no use of this feature
duke@435:     // for now, so it's not implemented.
duke@435:     assert(requested_address == NULL, "not implemented");
duke@435: 
duke@435:     base = os::reserve_memory_special(size);
duke@435: 
duke@435:     if (base != NULL) {
duke@435:       // Check alignment constraints
duke@435:       if (alignment > 0) {
duke@435:         assert((uintptr_t) base % alignment == 0,
duke@435:                "Large pages returned a non-aligned address");
duke@435:       }
duke@435:       _special = true;
duke@435:     } else {
duke@435:       // failed; try to reserve regular memory below
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   if (base == NULL) {
duke@435:     // Optimistically assume that the OSes returns an aligned base pointer.
duke@435:     // When reserving a large address range, most OSes seem to align to at
duke@435:     // least 64K.
duke@435: 
duke@435:     // If the memory was requested at a particular address, use
duke@435:     // os::attempt_reserve_memory_at() to avoid over mapping something
duke@435:     // important.  If available space is not detected, return NULL.
duke@435: 
duke@435:     if (requested_address != 0) {
duke@435:       base = os::attempt_reserve_memory_at(size, requested_address);
duke@435:     } else {
duke@435:       base = os::reserve_memory(size, NULL, alignment);
duke@435:     }
duke@435: 
duke@435:     if (base == NULL) return;
duke@435: 
duke@435:     // Check alignment constraints
duke@435:     if (alignment > 0 && ((size_t)base & alignment - 1) != 0) {
duke@435:       // Base not aligned, retry
duke@435:       if (!os::release_memory(base, size)) fatal("os::release_memory failed");
duke@435:       // Reserve size large enough to do manual alignment and
duke@435:       // increase size to a multiple of the desired alignment
duke@435:       size = align_size_up(size, alignment);
duke@435:       size_t extra_size = size + alignment;
duke@435:       char* extra_base = os::reserve_memory(extra_size, NULL, alignment);
duke@435:       if (extra_base == NULL) return;
duke@435:       // Do manual alignement
duke@435:       base = (char*) align_size_up((uintptr_t) extra_base, alignment);
duke@435:       assert(base >= extra_base, "just checking");
duke@435:       // Release unused areas
duke@435:       size_t unused_bottom_size = base - extra_base;
duke@435:       size_t unused_top_size = extra_size - size - unused_bottom_size;
duke@435:       assert(unused_bottom_size % os::vm_allocation_granularity() == 0,
duke@435:              "size not allocation aligned");
duke@435:       assert(unused_top_size % os::vm_allocation_granularity() == 0,
duke@435:              "size not allocation aligned");
duke@435:       if (unused_bottom_size > 0) {
duke@435:         os::release_memory(extra_base, unused_bottom_size);
duke@435:       }
duke@435:       if (unused_top_size > 0) {
duke@435:         os::release_memory(base + size, unused_top_size);
duke@435:       }
duke@435:     }
duke@435:   }
duke@435:   // Done
duke@435:   _base = base;
duke@435:   _size = size;
duke@435:   _alignment = MAX2(alignment, (size_t) os::vm_page_size());
duke@435: 
duke@435:   assert(markOopDesc::encode_pointer_as_mark(_base)->decode_pointer() == _base,
duke@435:          "area must be distinguisable from marks for mark-sweep");
duke@435:   assert(markOopDesc::encode_pointer_as_mark(&_base[size])->decode_pointer() == &_base[size],
duke@435:          "area must be distinguisable from marks for mark-sweep");
duke@435: }
duke@435: 
duke@435: 
duke@435: ReservedSpace::ReservedSpace(char* base, size_t size, size_t alignment,
duke@435:                              bool special) {
duke@435:   assert((size % os::vm_allocation_granularity()) == 0,
duke@435:          "size not allocation aligned");
duke@435:   _base = base;
duke@435:   _size = size;
duke@435:   _alignment = alignment;
duke@435:   _special = special;
duke@435: }
duke@435: 
duke@435: 
duke@435: ReservedSpace ReservedSpace::first_part(size_t partition_size, size_t alignment,
duke@435:                                         bool split, bool realloc) {
duke@435:   assert(partition_size <= size(), "partition failed");
duke@435:   if (split) {
duke@435:     os::split_reserved_memory(_base, _size, partition_size, realloc);
duke@435:   }
duke@435:   ReservedSpace result(base(), partition_size, alignment, special());
duke@435:   return result;
duke@435: }
duke@435: 
duke@435: 
duke@435: ReservedSpace
duke@435: ReservedSpace::last_part(size_t partition_size, size_t alignment) {
duke@435:   assert(partition_size <= size(), "partition failed");
duke@435:   ReservedSpace result(base() + partition_size, size() - partition_size,
duke@435:                        alignment, special());
duke@435:   return result;
duke@435: }
duke@435: 
duke@435: 
duke@435: size_t ReservedSpace::page_align_size_up(size_t size) {
duke@435:   return align_size_up(size, os::vm_page_size());
duke@435: }
duke@435: 
duke@435: 
duke@435: size_t ReservedSpace::page_align_size_down(size_t size) {
duke@435:   return align_size_down(size, os::vm_page_size());
duke@435: }
duke@435: 
duke@435: 
duke@435: size_t ReservedSpace::allocation_align_size_up(size_t size) {
duke@435:   return align_size_up(size, os::vm_allocation_granularity());
duke@435: }
duke@435: 
duke@435: 
duke@435: size_t ReservedSpace::allocation_align_size_down(size_t size) {
duke@435:   return align_size_down(size, os::vm_allocation_granularity());
duke@435: }
duke@435: 
duke@435: 
duke@435: void ReservedSpace::release() {
duke@435:   if (is_reserved()) {
duke@435:     if (special()) {
duke@435:       os::release_memory_special(_base, _size);
duke@435:     } else{
duke@435:       os::release_memory(_base, _size);
duke@435:     }
duke@435:     _base = NULL;
duke@435:     _size = 0;
duke@435:     _special = false;
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: // VirtualSpace
duke@435: 
duke@435: VirtualSpace::VirtualSpace() {
duke@435:   _low_boundary           = NULL;
duke@435:   _high_boundary          = NULL;
duke@435:   _low                    = NULL;
duke@435:   _high                   = NULL;
duke@435:   _lower_high             = NULL;
duke@435:   _middle_high            = NULL;
duke@435:   _upper_high             = NULL;
duke@435:   _lower_high_boundary    = NULL;
duke@435:   _middle_high_boundary   = NULL;
duke@435:   _upper_high_boundary    = NULL;
duke@435:   _lower_alignment        = 0;
duke@435:   _middle_alignment       = 0;
duke@435:   _upper_alignment        = 0;
duke@435: }
duke@435: 
duke@435: 
duke@435: bool VirtualSpace::initialize(ReservedSpace rs, size_t committed_size) {
duke@435:   if(!rs.is_reserved()) return false;  // allocation failed.
duke@435:   assert(_low_boundary == NULL, "VirtualSpace already initialized");
duke@435:   _low_boundary  = rs.base();
duke@435:   _high_boundary = low_boundary() + rs.size();
duke@435: 
duke@435:   _low = low_boundary();
duke@435:   _high = low();
duke@435: 
duke@435:   _special = rs.special();
duke@435: 
duke@435:   // When a VirtualSpace begins life at a large size, make all future expansion
duke@435:   // and shrinking occur aligned to a granularity of large pages.  This avoids
duke@435:   // fragmentation of physical addresses that inhibits the use of large pages
duke@435:   // by the OS virtual memory system.  Empirically,  we see that with a 4MB
duke@435:   // page size, the only spaces that get handled this way are codecache and
duke@435:   // the heap itself, both of which provide a substantial performance
duke@435:   // boost in many benchmarks when covered by large pages.
duke@435:   //
duke@435:   // No attempt is made to force large page alignment at the very top and
duke@435:   // bottom of the space if they are not aligned so already.
duke@435:   _lower_alignment  = os::vm_page_size();
duke@435:   _middle_alignment = os::page_size_for_region(rs.size(), rs.size(), 1);
duke@435:   _upper_alignment  = os::vm_page_size();
duke@435: 
duke@435:   // End of each region
duke@435:   _lower_high_boundary = (char*) round_to((intptr_t) low_boundary(), middle_alignment());
duke@435:   _middle_high_boundary = (char*) round_down((intptr_t) high_boundary(), middle_alignment());
duke@435:   _upper_high_boundary = high_boundary();
duke@435: 
duke@435:   // High address of each region
duke@435:   _lower_high = low_boundary();
duke@435:   _middle_high = lower_high_boundary();
duke@435:   _upper_high = middle_high_boundary();
duke@435: 
duke@435:   // commit to initial size
duke@435:   if (committed_size > 0) {
duke@435:     if (!expand_by(committed_size)) {
duke@435:       return false;
duke@435:     }
duke@435:   }
duke@435:   return true;
duke@435: }
duke@435: 
duke@435: 
duke@435: VirtualSpace::~VirtualSpace() {
duke@435:   release();
duke@435: }
duke@435: 
duke@435: 
duke@435: void VirtualSpace::release() {
duke@435:   (void)os::release_memory(low_boundary(), reserved_size());
duke@435:   _low_boundary           = NULL;
duke@435:   _high_boundary          = NULL;
duke@435:   _low                    = NULL;
duke@435:   _high                   = NULL;
duke@435:   _lower_high             = NULL;
duke@435:   _middle_high            = NULL;
duke@435:   _upper_high             = NULL;
duke@435:   _lower_high_boundary    = NULL;
duke@435:   _middle_high_boundary   = NULL;
duke@435:   _upper_high_boundary    = NULL;
duke@435:   _lower_alignment        = 0;
duke@435:   _middle_alignment       = 0;
duke@435:   _upper_alignment        = 0;
duke@435:   _special                = false;
duke@435: }
duke@435: 
duke@435: 
duke@435: size_t VirtualSpace::committed_size() const {
duke@435:   return pointer_delta(high(), low(), sizeof(char));
duke@435: }
duke@435: 
duke@435: 
duke@435: size_t VirtualSpace::reserved_size() const {
duke@435:   return pointer_delta(high_boundary(), low_boundary(), sizeof(char));
duke@435: }
duke@435: 
duke@435: 
duke@435: size_t VirtualSpace::uncommitted_size()  const {
duke@435:   return reserved_size() - committed_size();
duke@435: }
duke@435: 
duke@435: 
duke@435: bool VirtualSpace::contains(const void* p) const {
duke@435:   return low() <= (const char*) p && (const char*) p < high();
duke@435: }
duke@435: 
duke@435: /*
duke@435:    First we need to determine if a particular virtual space is using large
duke@435:    pages.  This is done at the initialize function and only virtual spaces
duke@435:    that are larger than LargePageSizeInBytes use large pages.  Once we
duke@435:    have determined this, all expand_by and shrink_by calls must grow and
duke@435:    shrink by large page size chunks.  If a particular request
duke@435:    is within the current large page, the call to commit and uncommit memory
duke@435:    can be ignored.  In the case that the low and high boundaries of this
duke@435:    space is not large page aligned, the pages leading to the first large
duke@435:    page address and the pages after the last large page address must be
duke@435:    allocated with default pages.
duke@435: */
duke@435: bool VirtualSpace::expand_by(size_t bytes, bool pre_touch) {
duke@435:   if (uncommitted_size() < bytes) return false;
duke@435: 
duke@435:   if (special()) {
duke@435:     // don't commit memory if the entire space is pinned in memory
duke@435:     _high += bytes;
duke@435:     return true;
duke@435:   }
duke@435: 
duke@435:   char* previous_high = high();
duke@435:   char* unaligned_new_high = high() + bytes;
duke@435:   assert(unaligned_new_high <= high_boundary(),
duke@435:          "cannot expand by more than upper boundary");
duke@435: 
duke@435:   // Calculate where the new high for each of the regions should be.  If
duke@435:   // the low_boundary() and high_boundary() are LargePageSizeInBytes aligned
duke@435:   // then the unaligned lower and upper new highs would be the
duke@435:   // lower_high() and upper_high() respectively.
duke@435:   char* unaligned_lower_new_high =
duke@435:     MIN2(unaligned_new_high, lower_high_boundary());
duke@435:   char* unaligned_middle_new_high =
duke@435:     MIN2(unaligned_new_high, middle_high_boundary());
duke@435:   char* unaligned_upper_new_high =
duke@435:     MIN2(unaligned_new_high, upper_high_boundary());
duke@435: 
duke@435:   // Align the new highs based on the regions alignment.  lower and upper
duke@435:   // alignment will always be default page size.  middle alignment will be
duke@435:   // LargePageSizeInBytes if the actual size of the virtual space is in
duke@435:   // fact larger than LargePageSizeInBytes.
duke@435:   char* aligned_lower_new_high =
duke@435:     (char*) round_to((intptr_t) unaligned_lower_new_high, lower_alignment());
duke@435:   char* aligned_middle_new_high =
duke@435:     (char*) round_to((intptr_t) unaligned_middle_new_high, middle_alignment());
duke@435:   char* aligned_upper_new_high =
duke@435:     (char*) round_to((intptr_t) unaligned_upper_new_high, upper_alignment());
duke@435: 
duke@435:   // Determine which regions need to grow in this expand_by call.
duke@435:   // If you are growing in the lower region, high() must be in that
duke@435:   // region so calcuate the size based on high().  For the middle and
duke@435:   // upper regions, determine the starting point of growth based on the
duke@435:   // location of high().  By getting the MAX of the region's low address
duke@435:   // (or the prevoius region's high address) and high(), we can tell if it
duke@435:   // is an intra or inter region growth.
duke@435:   size_t lower_needs = 0;
duke@435:   if (aligned_lower_new_high > lower_high()) {
duke@435:     lower_needs =
duke@435:       pointer_delta(aligned_lower_new_high, lower_high(), sizeof(char));
duke@435:   }
duke@435:   size_t middle_needs = 0;
duke@435:   if (aligned_middle_new_high > middle_high()) {
duke@435:     middle_needs =
duke@435:       pointer_delta(aligned_middle_new_high, middle_high(), sizeof(char));
duke@435:   }
duke@435:   size_t upper_needs = 0;
duke@435:   if (aligned_upper_new_high > upper_high()) {
duke@435:     upper_needs =
duke@435:       pointer_delta(aligned_upper_new_high, upper_high(), sizeof(char));
duke@435:   }
duke@435: 
duke@435:   // Check contiguity.
duke@435:   assert(low_boundary() <= lower_high() &&
duke@435:          lower_high() <= lower_high_boundary(),
duke@435:          "high address must be contained within the region");
duke@435:   assert(lower_high_boundary() <= middle_high() &&
duke@435:          middle_high() <= middle_high_boundary(),
duke@435:          "high address must be contained within the region");
duke@435:   assert(middle_high_boundary() <= upper_high() &&
duke@435:          upper_high() <= upper_high_boundary(),
duke@435:          "high address must be contained within the region");
duke@435: 
duke@435:   // Commit regions
duke@435:   if (lower_needs > 0) {
duke@435:     assert(low_boundary() <= lower_high() &&
duke@435:            lower_high() + lower_needs <= lower_high_boundary(),
duke@435:            "must not expand beyond region");
duke@435:     if (!os::commit_memory(lower_high(), lower_needs)) {
duke@435:       debug_only(warning("os::commit_memory failed"));
duke@435:       return false;
duke@435:     } else {
duke@435:       _lower_high += lower_needs;
duke@435:      }
duke@435:   }
duke@435:   if (middle_needs > 0) {
duke@435:     assert(lower_high_boundary() <= middle_high() &&
duke@435:            middle_high() + middle_needs <= middle_high_boundary(),
duke@435:            "must not expand beyond region");
duke@435:     if (!os::commit_memory(middle_high(), middle_needs, middle_alignment())) {
duke@435:       debug_only(warning("os::commit_memory failed"));
duke@435:       return false;
duke@435:     }
duke@435:     _middle_high += middle_needs;
duke@435:   }
duke@435:   if (upper_needs > 0) {
duke@435:     assert(middle_high_boundary() <= upper_high() &&
duke@435:            upper_high() + upper_needs <= upper_high_boundary(),
duke@435:            "must not expand beyond region");
duke@435:     if (!os::commit_memory(upper_high(), upper_needs)) {
duke@435:       debug_only(warning("os::commit_memory failed"));
duke@435:       return false;
duke@435:     } else {
duke@435:       _upper_high += upper_needs;
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   if (pre_touch || AlwaysPreTouch) {
duke@435:     int vm_ps = os::vm_page_size();
duke@435:     for (char* curr = previous_high;
duke@435:          curr < unaligned_new_high;
duke@435:          curr += vm_ps) {
duke@435:       // Note the use of a write here; originally we tried just a read, but
duke@435:       // since the value read was unused, the optimizer removed the read.
duke@435:       // If we ever have a concurrent touchahead thread, we'll want to use
duke@435:       // a read, to avoid the potential of overwriting data (if a mutator
duke@435:       // thread beats the touchahead thread to a page).  There are various
duke@435:       // ways of making sure this read is not optimized away: for example,
duke@435:       // generating the code for a read procedure at runtime.
duke@435:       *curr = 0;
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   _high += bytes;
duke@435:   return true;
duke@435: }
duke@435: 
duke@435: // A page is uncommitted if the contents of the entire page is deemed unusable.
duke@435: // Continue to decrement the high() pointer until it reaches a page boundary
duke@435: // in which case that particular page can now be uncommitted.
duke@435: void VirtualSpace::shrink_by(size_t size) {
duke@435:   if (committed_size() < size)
duke@435:     fatal("Cannot shrink virtual space to negative size");
duke@435: 
duke@435:   if (special()) {
duke@435:     // don't uncommit if the entire space is pinned in memory
duke@435:     _high -= size;
duke@435:     return;
duke@435:   }
duke@435: 
duke@435:   char* unaligned_new_high = high() - size;
duke@435:   assert(unaligned_new_high >= low_boundary(), "cannot shrink past lower boundary");
duke@435: 
duke@435:   // Calculate new unaligned address
duke@435:   char* unaligned_upper_new_high =
duke@435:     MAX2(unaligned_new_high, middle_high_boundary());
duke@435:   char* unaligned_middle_new_high =
duke@435:     MAX2(unaligned_new_high, lower_high_boundary());
duke@435:   char* unaligned_lower_new_high =
duke@435:     MAX2(unaligned_new_high, low_boundary());
duke@435: 
duke@435:   // Align address to region's alignment
duke@435:   char* aligned_upper_new_high =
duke@435:     (char*) round_to((intptr_t) unaligned_upper_new_high, upper_alignment());
duke@435:   char* aligned_middle_new_high =
duke@435:     (char*) round_to((intptr_t) unaligned_middle_new_high, middle_alignment());
duke@435:   char* aligned_lower_new_high =
duke@435:     (char*) round_to((intptr_t) unaligned_lower_new_high, lower_alignment());
duke@435: 
duke@435:   // Determine which regions need to shrink
duke@435:   size_t upper_needs = 0;
duke@435:   if (aligned_upper_new_high < upper_high()) {
duke@435:     upper_needs =
duke@435:       pointer_delta(upper_high(), aligned_upper_new_high, sizeof(char));
duke@435:   }
duke@435:   size_t middle_needs = 0;
duke@435:   if (aligned_middle_new_high < middle_high()) {
duke@435:     middle_needs =
duke@435:       pointer_delta(middle_high(), aligned_middle_new_high, sizeof(char));
duke@435:   }
duke@435:   size_t lower_needs = 0;
duke@435:   if (aligned_lower_new_high < lower_high()) {
duke@435:     lower_needs =
duke@435:       pointer_delta(lower_high(), aligned_lower_new_high, sizeof(char));
duke@435:   }
duke@435: 
duke@435:   // Check contiguity.
duke@435:   assert(middle_high_boundary() <= upper_high() &&
duke@435:          upper_high() <= upper_high_boundary(),
duke@435:          "high address must be contained within the region");
duke@435:   assert(lower_high_boundary() <= middle_high() &&
duke@435:          middle_high() <= middle_high_boundary(),
duke@435:          "high address must be contained within the region");
duke@435:   assert(low_boundary() <= lower_high() &&
duke@435:          lower_high() <= lower_high_boundary(),
duke@435:          "high address must be contained within the region");
duke@435: 
duke@435:   // Uncommit
duke@435:   if (upper_needs > 0) {
duke@435:     assert(middle_high_boundary() <= aligned_upper_new_high &&
duke@435:            aligned_upper_new_high + upper_needs <= upper_high_boundary(),
duke@435:            "must not shrink beyond region");
duke@435:     if (!os::uncommit_memory(aligned_upper_new_high, upper_needs)) {
duke@435:       debug_only(warning("os::uncommit_memory failed"));
duke@435:       return;
duke@435:     } else {
duke@435:       _upper_high -= upper_needs;
duke@435:     }
duke@435:   }
duke@435:   if (middle_needs > 0) {
duke@435:     assert(lower_high_boundary() <= aligned_middle_new_high &&
duke@435:            aligned_middle_new_high + middle_needs <= middle_high_boundary(),
duke@435:            "must not shrink beyond region");
duke@435:     if (!os::uncommit_memory(aligned_middle_new_high, middle_needs)) {
duke@435:       debug_only(warning("os::uncommit_memory failed"));
duke@435:       return;
duke@435:     } else {
duke@435:       _middle_high -= middle_needs;
duke@435:     }
duke@435:   }
duke@435:   if (lower_needs > 0) {
duke@435:     assert(low_boundary() <= aligned_lower_new_high &&
duke@435:            aligned_lower_new_high + lower_needs <= lower_high_boundary(),
duke@435:            "must not shrink beyond region");
duke@435:     if (!os::uncommit_memory(aligned_lower_new_high, lower_needs)) {
duke@435:       debug_only(warning("os::uncommit_memory failed"));
duke@435:       return;
duke@435:     } else {
duke@435:       _lower_high -= lower_needs;
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   _high -= size;
duke@435: }
duke@435: 
duke@435: #ifndef PRODUCT
duke@435: void VirtualSpace::check_for_contiguity() {
duke@435:   // Check contiguity.
duke@435:   assert(low_boundary() <= lower_high() &&
duke@435:          lower_high() <= lower_high_boundary(),
duke@435:          "high address must be contained within the region");
duke@435:   assert(lower_high_boundary() <= middle_high() &&
duke@435:          middle_high() <= middle_high_boundary(),
duke@435:          "high address must be contained within the region");
duke@435:   assert(middle_high_boundary() <= upper_high() &&
duke@435:          upper_high() <= upper_high_boundary(),
duke@435:          "high address must be contained within the region");
duke@435:   assert(low() >= low_boundary(), "low");
duke@435:   assert(low_boundary() <= lower_high_boundary(), "lower high boundary");
duke@435:   assert(upper_high_boundary() <= high_boundary(), "upper high boundary");
duke@435:   assert(high() <= upper_high(), "upper high");
duke@435: }
duke@435: 
duke@435: void VirtualSpace::print() {
duke@435:   tty->print   ("Virtual space:");
duke@435:   if (special()) tty->print(" (pinned in memory)");
duke@435:   tty->cr();
duke@435:   tty->print_cr(" - committed: %ld", committed_size());
duke@435:   tty->print_cr(" - reserved:  %ld", reserved_size());
duke@435:   tty->print_cr(" - [low, high]:     [" INTPTR_FORMAT ", " INTPTR_FORMAT "]",  low(), high());
duke@435:   tty->print_cr(" - [low_b, high_b]: [" INTPTR_FORMAT ", " INTPTR_FORMAT "]",  low_boundary(), high_boundary());
duke@435: }
duke@435: 
duke@435: #endif