JDK14/Java14源码在线阅读
/*
* Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "asm/codeBuffer.hpp"
#include "code/oopRecorder.inline.hpp"
#include "compiler/disassembler.hpp"
#include "oops/methodData.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/icache.hpp"
#include "runtime/safepointVerifiers.hpp"
#include "utilities/align.hpp"
#include "utilities/copy.hpp"
#include "utilities/xmlstream.hpp"
// The structure of a CodeSection:
//
// _start -> +----------------+
// | machine code...|
// _end -> |----------------|
// | |
// | (empty) |
// | |
// | |
// +----------------+
// _limit -> | |
//
// _locs_start -> +----------------+
// |reloc records...|
// |----------------|
// _locs_end -> | |
// | |
// | (empty) |
// | |
// | |
// +----------------+
// _locs_limit -> | |
// The _end (resp. _limit) pointer refers to the first
// unused (resp. unallocated) byte.
// The structure of the CodeBuffer while code is being accumulated:
//
// _total_start -> \
// _insts._start -> +----------------+
// | |
// | Code |
// | |
// _stubs._start -> |----------------|
// | |
// | Stubs | (also handlers for deopt/exception)
// | |
// _consts._start -> |----------------|
// | |
// | Constants |
// | |
// +----------------+
// + _total_size -> | |
//
// When the code and relocations are copied to the code cache,
// the empty parts of each section are removed, and everything
// is copied into contiguous locations.
typedef CodeBuffer::csize_t csize_t; // file-local definition
// External buffer, in a predefined CodeBlob.
// Important: The code_start must be taken exactly, and not realigned.
CodeBuffer::CodeBuffer(CodeBlob* blob) {
// Provide code buffer with meaningful name
initialize_misc(blob->name());
initialize(blob->content_begin(), blob->content_size());
verify_section_allocation();
}
void CodeBuffer::initialize(csize_t code_size, csize_t locs_size) {
// Compute maximal alignment.
int align = _insts.alignment();
// Always allow for empty slop around each section.
int slop = (int) CodeSection::end_slop();
assert(blob() == NULL, "only once");
set_blob(BufferBlob::create(_name, code_size + (align+slop) * (SECT_LIMIT+1)));
if (blob() == NULL) {
// The assembler constructor will throw a fatal on an empty CodeBuffer.
return; // caller must test this
}
// Set up various pointers into the blob.
initialize(_total_start, _total_size);
assert((uintptr_t)insts_begin() % CodeEntryAlignment == 0, "instruction start not code entry aligned");
pd_initialize();
if (locs_size != 0) {
_insts.initialize_locs(locs_size / sizeof(relocInfo));
}
verify_section_allocation();
}
CodeBuffer::~CodeBuffer() {
verify_section_allocation();
// If we allocate our code buffer from the CodeCache
// via a BufferBlob, and it's not permanent, then
// free the BufferBlob.
// The rest of the memory will be freed when the ResourceObj
// is released.
for (CodeBuffer* cb = this; cb != NULL; cb = cb->before_expand()) {
// Previous incarnations of this buffer are held live, so that internal
// addresses constructed before expansions will not be confused.
cb->free_blob();
}
// free any overflow storage
delete _overflow_arena;
// Claim is that stack allocation ensures resources are cleaned up.
// This is resource clean up, let's hope that all were properly copied out.
free_strings();
#ifdef ASSERT
// Save allocation type to execute assert in ~ResourceObj()
// which is called after this destructor.
assert(_default_oop_recorder.allocated_on_stack(), "should be embedded object");
ResourceObj::allocation_type at = _default_oop_recorder.get_allocation_type();
Copy::fill_to_bytes(this, sizeof(*this), badResourceValue);
ResourceObj::set_allocation_type((address)(&_default_oop_recorder), at);
#endif
}
void CodeBuffer::initialize_oop_recorder(OopRecorder* r) {
assert(_oop_recorder == &_default_oop_recorder && _default_oop_recorder.is_unused(), "do this once");
DEBUG_ONLY(_default_oop_recorder.freeze()); // force unused OR to be frozen
_oop_recorder = r;
}
void CodeBuffer::initialize_section_size(CodeSection* cs, csize_t size) {
assert(cs != &_insts, "insts is the memory provider, not the consumer");
csize_t slop = CodeSection::end_slop(); // margin between sections
int align = cs->alignment();
assert(is_power_of_2(align), "sanity");
address start = _insts._start;
address limit = _insts._limit;
address middle = limit - size;
middle -= (intptr_t)middle & (align-1); // align the division point downward
guarantee(middle - slop > start, "need enough space to divide up");
_insts._limit = middle - slop; // subtract desired space, plus slop
cs->initialize(middle, limit - middle);
assert(cs->start() == middle, "sanity");
assert(cs->limit() == limit, "sanity");
// give it some relocations to start with, if the main section has them
if (_insts.has_locs()) cs->initialize_locs(1);
}
void CodeBuffer::freeze_section(CodeSection* cs) {
CodeSection* next_cs = (cs == consts())? NULL: code_section(cs->index()+1);
csize_t frozen_size = cs->size();
if (next_cs != NULL) {
frozen_size = next_cs->align_at_start(frozen_size);
}
address old_limit = cs->limit();
address new_limit = cs->start() + frozen_size;
relocInfo* old_locs_limit = cs->locs_limit();
relocInfo* new_locs_limit = cs->locs_end();
// Patch the limits.
cs->_limit = new_limit;
cs->_locs_limit = new_locs_limit;
cs->_frozen = true;
if (next_cs != NULL && !next_cs->is_allocated() && !next_cs->is_frozen()) {
// Give remaining buffer space to the following section.
next_cs->initialize(new_limit, old_limit - new_limit);
next_cs->initialize_shared_locs(new_locs_limit,
old_locs_limit - new_locs_limit);
}
}
void CodeBuffer::set_blob(BufferBlob* blob) {
_blob = blob;
if (blob != NULL) {
address start = blob->content_begin();
address end = blob->content_end();
// Round up the starting address.
int align = _insts.alignment();
start += (-(intptr_t)start) & (align-1);
_total_start = start;
_total_size = end - start;
} else {
#ifdef ASSERT
// Clean out dangling pointers.
_total_start = badAddress;
_consts._start = _consts._end = badAddress;
_insts._start = _insts._end = badAddress;
_stubs._start = _stubs._end = badAddress;
#endif //ASSERT
}
}
void CodeBuffer::free_blob() {
if (_blob != NULL) {
BufferBlob::free(_blob);
set_blob(NULL);
}
}
const char* CodeBuffer::code_section_name(int n) {
#ifdef PRODUCT
return NULL;
#else //PRODUCT
switch (n) {
case SECT_CONSTS: return "consts";
case SECT_INSTS: return "insts";
case SECT_STUBS: return "stubs";
default: return NULL;
}
#endif //PRODUCT
}
int CodeBuffer::section_index_of(address addr) const {
for (int n = 0; n < (int)SECT_LIMIT; n++) {
const CodeSection* cs = code_section(n);
if (cs->allocates(addr)) return n;
}
return SECT_NONE;
}
int CodeBuffer::locator(address addr) const {
for (int n = 0; n < (int)SECT_LIMIT; n++) {
const CodeSection* cs = code_section(n);
if (cs->allocates(addr)) {
return locator(addr - cs->start(), n);
}
}
return -1;
}
address CodeBuffer::locator_address(int locator) const {
if (locator < 0) return NULL;
address start = code_section(locator_sect(locator))->start();
return start + locator_pos(locator);
}
bool CodeBuffer::is_backward_branch(Label& L) {
return L.is_bound() && insts_end() <= locator_address(L.loc());
}
address CodeBuffer::decode_begin() {
address begin = _insts.start();
if (_decode_begin != NULL && _decode_begin > begin)
begin = _decode_begin;
return begin;
}
GrowableArray<int>* CodeBuffer::create_patch_overflow() {
if (_overflow_arena == NULL) {
_overflow_arena = new (mtCode) Arena(mtCode);
}
return new (_overflow_arena) GrowableArray<int>(_overflow_arena, 8, 0, 0);
}
// Helper function for managing labels and their target addresses.
// Returns a sensible address, and if it is not the label's final
// address, notes the dependency (at 'branch_pc') on the label.
address CodeSection::target(Label& L, address branch_pc) {
if (L.is_bound()) {
int loc = L.loc();
if (index() == CodeBuffer::locator_sect(loc)) {
return start() + CodeBuffer::locator_pos(loc);
} else {
return outer()->locator_address(loc);
}
} else {
assert(allocates2(branch_pc), "sanity");
address base = start();
int patch_loc = CodeBuffer::locator(branch_pc - base, index());
L.add_patch_at(outer(), patch_loc);
// Need to return a pc, doesn't matter what it is since it will be
// replaced during resolution later.
// Don't return NULL or badAddress, since branches shouldn't overflow.
// Don't return base either because that could overflow displacements
// for shorter branches. It will get checked when bound.
return branch_pc;
}
}
void CodeSection::relocate(address at, relocInfo::relocType rtype, int format, jint method_index) {
RelocationHolder rh;
switch (rtype) {
case relocInfo::none: return;
case relocInfo::opt_virtual_call_type: {
rh = opt_virtual_call_Relocation::spec(method_index);
break;
}
case relocInfo::static_call_type: {
rh = static_call_Relocation::spec(method_index);
break;
}
case relocInfo::virtual_call_type: {
assert(method_index == 0, "resolved method overriding is not supported");
rh = Relocation::spec_simple(rtype);
break;
}
default: {
rh = Relocation::spec_simple(rtype);
break;
}
}
relocate(at, rh, format);
}
void CodeSection::relocate(address at, RelocationHolder const& spec, int format) {
// Do not relocate in scratch buffers.
if (scratch_emit()) { return; }
Relocation* reloc = spec.reloc();
relocInfo::relocType rtype = (relocInfo::relocType) reloc->type();
if (rtype == relocInfo::none) return;
// The assertion below has been adjusted, to also work for
// relocation for fixup. Sometimes we want to put relocation
// information for the next instruction, since it will be patched
// with a call.
assert(start() <= at && at <= end()+1,
"cannot relocate data outside code boundaries");
if (!has_locs()) {
// no space for relocation information provided => code cannot be
// relocated. Make sure that relocate is only called with rtypes
// that can be ignored for this kind of code.
assert(rtype == relocInfo::none ||
rtype == relocInfo::runtime_call_type ||
rtype == relocInfo::internal_word_type||
rtype == relocInfo::section_word_type ||
rtype == relocInfo::external_word_type,
"code needs relocation information");
// leave behind an indication that we attempted a relocation
DEBUG_ONLY(_locs_start = _locs_limit = (relocInfo*)badAddress);
return;
}
// Advance the point, noting the offset we'll have to record.
csize_t offset = at - locs_point();
set_locs_point(at);
// Test for a couple of overflow conditions; maybe expand the buffer.
relocInfo* end = locs_end();
relocInfo* req = end + relocInfo::length_limit;
// Check for (potential) overflow
if (req >= locs_limit() || offset >= relocInfo::offset_limit()) {
req += (uint)offset / (uint)relocInfo::offset_limit();
if (req >= locs_limit()) {
// Allocate or reallocate.
expand_locs(locs_count() + (req - end));
// reload pointer
end = locs_end();
}
}
// If the offset is giant, emit filler relocs, of type 'none', but
// each carrying the largest possible offset, to advance the locs_point.
while (offset >= relocInfo::offset_limit()) {
assert(end < locs_limit(), "adjust previous paragraph of code");
*end++ = filler_relocInfo();
offset -= filler_relocInfo().addr_offset();
}
// If it's a simple reloc with no data, we'll just write (rtype | offset).
(*end) = relocInfo(rtype, offset, format);
// If it has data, insert the prefix, as (data_prefix_tag | data1), data2.
end->initialize(this, reloc);
}
void CodeSection::initialize_locs(int locs_capacity) {
assert(_locs_start == NULL, "only one locs init step, please");
// Apply a priori lower limits to relocation size:
csize_t min_locs = MAX2(size() / 16, (csize_t)4);
if (locs_capacity < min_locs) locs_capacity = min_locs;
relocInfo* locs_start = NEW_RESOURCE_ARRAY(relocInfo, locs_capacity);
_locs_start = locs_start;
_locs_end = locs_start;
_locs_limit = locs_start + locs_capacity;
_locs_own = true;
}
void CodeSection::initialize_shared_locs(relocInfo* buf, int length) {
assert(_locs_start == NULL, "do this before locs are allocated");
// Internal invariant: locs buf must be fully aligned.
// See copy_relocations_to() below.
while ((uintptr_t)buf % HeapWordSize != 0 && length > 0) {
++buf; --length;
}
if (length > 0) {
_locs_start = buf;
_locs_end = buf;
_locs_limit = buf + length;
_locs_own = false;
}
}
void CodeSection::initialize_locs_from(const CodeSection* source_cs) {
int lcount = source_cs->locs_count();
if (lcount != 0) {
initialize_shared_locs(source_cs->locs_start(), lcount);
_locs_end = _locs_limit = _locs_start + lcount;
assert(is_allocated(), "must have copied code already");
set_locs_point(start() + source_cs->locs_point_off());
}
assert(this->locs_count() == source_cs->locs_count(), "sanity");
}
void CodeSection::expand_locs(int new_capacity) {
if (_locs_start == NULL) {
initialize_locs(new_capacity);
return;
} else {
int old_count = locs_count();
int old_capacity = locs_capacity();
if (new_capacity < old_capacity * 2)
new_capacity = old_capacity * 2;
relocInfo* locs_start;
if (_locs_own) {
locs_start = REALLOC_RESOURCE_ARRAY(relocInfo, _locs_start, old_capacity, new_capacity);
} else {
locs_start = NEW_RESOURCE_ARRAY(relocInfo, new_capacity);
Copy::conjoint_jbytes(_locs_start, locs_start, old_capacity * sizeof(relocInfo));
_locs_own = true;
}
_locs_start = locs_start;
_locs_end = locs_start + old_count;
_locs_limit = locs_start + new_capacity;
}
}
/// Support for emitting the code to its final location.
/// The pattern is the same for all functions.
/// We iterate over all the sections, padding each to alignment.
csize_t CodeBuffer::total_content_size() const {
csize_t size_so_far = 0;
for (int n = 0; n < (int)SECT_LIMIT; n++) {
const CodeSection* cs = code_section(n);
if (cs->is_empty()) continue; // skip trivial section
size_so_far = cs->align_at_start(size_so_far);
size_so_far += cs->size();
}
return size_so_far;
}
void CodeBuffer::compute_final_layout(CodeBuffer* dest) const {
address buf = dest->_total_start;
csize_t buf_offset = 0;
assert(dest->_total_size >= total_content_size(), "must be big enough");
{
// not sure why this is here, but why not...
int alignSize = MAX2((intx) sizeof(jdouble), CodeEntryAlignment);
assert( (dest->_total_start - _insts.start()) % alignSize == 0, "copy must preserve alignment");
}
const CodeSection* prev_cs = NULL;
CodeSection* prev_dest_cs = NULL;
for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
// figure compact layout of each section
const CodeSection* cs = code_section(n);
csize_t csize = cs->size();
CodeSection* dest_cs = dest->code_section(n);
if (!cs->is_empty()) {
// Compute initial padding; assign it to the previous non-empty guy.
// Cf. figure_expanded_capacities.
csize_t padding = cs->align_at_start(buf_offset) - buf_offset;
if (prev_dest_cs != NULL) {
if (padding != 0) {
buf_offset += padding;
prev_dest_cs->_limit += padding;
}
} else {
guarantee(padding == 0, "In first iteration no padding should be needed.");
}
#ifdef ASSERT
if (prev_cs != NULL && prev_cs->is_frozen() && n < (SECT_LIMIT - 1)) {
// Make sure the ends still match up.
// This is important because a branch in a frozen section
// might target code in a following section, via a Label,
// and without a relocation record. See Label::patch_instructions.
address dest_start = buf+buf_offset;
csize_t start2start = cs->start() - prev_cs->start();
csize_t dest_start2start = dest_start - prev_dest_cs->start();
assert(start2start == dest_start2start, "cannot stretch frozen sect");
}
#endif //ASSERT
prev_dest_cs = dest_cs;
prev_cs = cs;
}
debug_only(dest_cs->_start = NULL); // defeat double-initialization assert
dest_cs->initialize(buf+buf_offset, csize);
dest_cs->set_end(buf+buf_offset+csize);
assert(dest_cs->is_allocated(), "must always be allocated");
assert(cs->is_empty() == dest_cs->is_empty(), "sanity");
buf_offset += csize;
}
// Done calculating sections; did it come out to the right end?
assert(buf_offset == total_content_size(), "sanity");
dest->verify_section_allocation();
}
// Append an oop reference that keeps the class alive.
static void append_oop_references(GrowableArray<oop>* oops, Klass* k) {
oop cl = k->klass_holder();
if (cl != NULL && !oops->contains(cl)) {
oops->append(cl);
}
}
void CodeBuffer::finalize_oop_references(const methodHandle& mh) {
NoSafepointVerifier nsv;
GrowableArray<oop> oops;
// Make sure that immediate metadata records something in the OopRecorder
for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
// pull code out of each section
CodeSection* cs = code_section(n);
if (cs->is_empty()) continue; // skip trivial section
RelocIterator iter(cs);
while (iter.next()) {
if (iter.type() == relocInfo::metadata_type) {
metadata_Relocation* md = iter.metadata_reloc();
if (md->metadata_is_immediate()) {
Metadata* m = md->metadata_value();
if (oop_recorder()->is_real(m)) {
if (m->is_methodData()) {
m = ((MethodData*)m)->method();
}
if (m->is_method()) {
m = ((Method*)m)->method_holder();
}
if (m->is_klass()) {
append_oop_references(&oops, (Klass*)m);
} else {
// XXX This will currently occur for MDO which don't
// have a backpointer. This has to be fixed later.
m->print();
ShouldNotReachHere();
}
}
}
}
}
}
if (!oop_recorder()->is_unused()) {
for (int i = 0; i < oop_recorder()->metadata_count(); i++) {
Metadata* m = oop_recorder()->metadata_at(i);
if (oop_recorder()->is_real(m)) {
if (m->is_methodData()) {
m = ((MethodData*)m)->method();
}
if (m->is_method()) {
m = ((Method*)m)->method_holder();
}
if (m->is_klass()) {
append_oop_references(&oops, (Klass*)m);
} else {
m->print();
ShouldNotReachHere();
}
}
}
}
// Add the class loader of Method* for the nmethod itself
append_oop_references(&oops, mh->method_holder());
// Add any oops that we've found
Thread* thread = Thread::current();
for (int i = 0; i < oops.length(); i++) {
oop_recorder()->find_index((jobject)thread->handle_area()->allocate_handle(oops.at(i)));
}
}
csize_t CodeBuffer::total_offset_of(const CodeSection* cs) const {
csize_t size_so_far = 0;
for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
const CodeSection* cur_cs = code_section(n);
if (!cur_cs->is_empty()) {
size_so_far = cur_cs->align_at_start(size_so_far);
}
if (cur_cs->index() == cs->index()) {
return size_so_far;
}
size_so_far += cur_cs->size();
}
ShouldNotReachHere();
return -1;
}
csize_t CodeBuffer::total_relocation_size() const {
csize_t total = copy_relocations_to(NULL); // dry run only
return (csize_t) align_up(total, HeapWordSize);
}
csize_t CodeBuffer::copy_relocations_to(address buf, csize_t buf_limit, bool only_inst) const {
csize_t buf_offset = 0;
csize_t code_end_so_far = 0;
csize_t code_point_so_far = 0;
assert((uintptr_t)buf % HeapWordSize == 0, "buf must be fully aligned");
assert(buf_limit % HeapWordSize == 0, "buf must be evenly sized");
for (int n = (int) SECT_FIRST; n < (int)SECT_LIMIT; n++) {
if (only_inst && (n != (int)SECT_INSTS)) {
// Need only relocation info for code.
continue;
}
// pull relocs out of each section
const CodeSection* cs = code_section(n);
assert(!(cs->is_empty() && cs->locs_count() > 0), "sanity");
if (cs->is_empty()) continue; // skip trivial section
relocInfo* lstart = cs->locs_start();
relocInfo* lend = cs->locs_end();
csize_t lsize = (csize_t)( (address)lend - (address)lstart );
csize_t csize = cs->size();
code_end_so_far = cs->align_at_start(code_end_so_far);
if (lsize > 0) {
// Figure out how to advance the combined relocation point
// first to the beginning of this section.
// We'll insert one or more filler relocs to span that gap.
// (Don't bother to improve this by editing the first reloc's offset.)
csize_t new_code_point = code_end_so_far;
for (csize_t jump;
code_point_so_far < new_code_point;
code_point_so_far += jump) {
jump = new_code_point - code_point_so_far;
relocInfo filler = filler_relocInfo();
if (jump >= filler.addr_offset()) {
jump = filler.addr_offset();
} else { // else shrink the filler to fit
filler = relocInfo(relocInfo::none, jump);
}
if (buf != NULL) {
assert(buf_offset + (csize_t)sizeof(filler) <= buf_limit, "filler in bounds");
*(relocInfo*)(buf+buf_offset) = filler;
}
buf_offset += sizeof(filler);
}
// Update code point and end to skip past this section:
csize_t last_code_point = code_end_so_far + cs->locs_point_off();
assert(code_point_so_far <= last_code_point, "sanity");
code_point_so_far = last_code_point; // advance past this guy's relocs
}
code_end_so_far += csize; // advance past this guy's instructions too
// Done with filler; emit the real relocations:
if (buf != NULL && lsize != 0) {
assert(buf_offset + lsize <= buf_limit, "target in bounds");
assert((uintptr_t)lstart % HeapWordSize == 0, "sane start");
if (buf_offset % HeapWordSize == 0) {
// Use wordwise copies if possible:
Copy::disjoint_words((HeapWord*)lstart,
(HeapWord*)(buf+buf_offset),
(lsize + HeapWordSize-1) / HeapWordSize);
} else {
Copy::conjoint_jbytes(lstart, buf+buf_offset, lsize);
}
}
buf_offset += lsize;
}
// Align end of relocation info in target.
while (buf_offset % HeapWordSize != 0) {
if (buf != NULL) {
relocInfo padding = relocInfo(relocInfo::none, 0);
assert(buf_offset + (csize_t)sizeof(padding) <= buf_limit, "padding in bounds");
*(relocInfo*)(buf+buf_offset) = padding;
}
buf_offset += sizeof(relocInfo);
}
assert(only_inst || code_end_so_far == total_content_size(), "sanity");
return buf_offset;
}
csize_t CodeBuffer::copy_relocations_to(CodeBlob* dest) const {
address buf = NULL;
csize_t buf_offset = 0;
csize_t buf_limit = 0;
if (dest != NULL) {
buf = (address)dest->relocation_begin();
buf_limit = (address)dest->relocation_end() - buf;
}
// if dest == NULL, this is just the sizing pass
//
buf_offset = copy_relocations_to(buf, buf_limit, false);
return buf_offset;
}
void CodeBuffer::copy_code_to(CodeBlob* dest_blob) {
#ifndef PRODUCT
if (PrintNMethods && (WizardMode || Verbose)) {
tty->print("done with CodeBuffer:");
((CodeBuffer*)this)->print();
}
#endif //PRODUCT
CodeBuffer dest(dest_blob);
assert(dest_blob->content_size() >= total_content_size(), "good sizing");
this->compute_final_layout(&dest);
// Set beginning of constant table before relocating.
dest_blob->set_ctable_begin(dest.consts()->start());
relocate_code_to(&dest);
// transfer strings and comments from buffer to blob
dest_blob->set_strings(_code_strings);
// Done moving code bytes; were they the right size?
assert((int)align_up(dest.total_content_size(), oopSize) == dest_blob->content_size(), "sanity");
// Flush generated code
ICache::invalidate_range(dest_blob->code_begin(), dest_blob->code_size());
}
// Move all my code into another code buffer. Consult applicable
// relocs to repair embedded addresses. The layout in the destination
// CodeBuffer is different to the source CodeBuffer: the destination
// CodeBuffer gets the final layout (consts, insts, stubs in order of
// ascending address).
void CodeBuffer::relocate_code_to(CodeBuffer* dest) const {
address dest_end = dest->_total_start + dest->_total_size;
address dest_filled = NULL;
for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
// pull code out of each section
const CodeSection* cs = code_section(n);
if (cs->is_empty()) continue; // skip trivial section
CodeSection* dest_cs = dest->code_section(n);
assert(cs->size() == dest_cs->size(), "sanity");
csize_t usize = dest_cs->size();
csize_t wsize = align_up(usize, HeapWordSize);
assert(dest_cs->start() + wsize <= dest_end, "no overflow");
// Copy the code as aligned machine words.
// This may also include an uninitialized partial word at the end.
Copy::disjoint_words((HeapWord*)cs->start(),
(HeapWord*)dest_cs->start(),
wsize / HeapWordSize);
if (dest->blob() == NULL) {
// Destination is a final resting place, not just another buffer.
// Normalize uninitialized bytes in the final padding.
Copy::fill_to_bytes(dest_cs->end(), dest_cs->remaining(),
Assembler::code_fill_byte());
}
// Keep track of the highest filled address
dest_filled = MAX2(dest_filled, dest_cs->end() + dest_cs->remaining());
assert(cs->locs_start() != (relocInfo*)badAddress,
"this section carries no reloc storage, but reloc was attempted");
// Make the new code copy use the old copy's relocations:
dest_cs->initialize_locs_from(cs);
}
// Do relocation after all sections are copied.
// This is necessary if the code uses constants in stubs, which are
// relocated when the corresponding instruction in the code (e.g., a
// call) is relocated. Stubs are placed behind the main code
// section, so that section has to be copied before relocating.
for (int n = (int) SECT_FIRST; n < (int)SECT_LIMIT; n++) {
// pull code out of each section
const CodeSection* cs = code_section(n);
if (cs->is_empty()) continue; // skip trivial section
CodeSection* dest_cs = dest->code_section(n);
{ // Repair the pc relative information in the code after the move
RelocIterator iter(dest_cs);
while (iter.next()) {
iter.reloc()->fix_relocation_after_move(this, dest);
}
}
}
if (dest->blob() == NULL && dest_filled != NULL) {
// Destination is a final resting place, not just another buffer.
// Normalize uninitialized bytes in the final padding.
Copy::fill_to_bytes(dest_filled, dest_end - dest_filled,
Assembler::code_fill_byte());
}
}
csize_t CodeBuffer::figure_expanded_capacities(CodeSection* which_cs,
csize_t amount,
csize_t* new_capacity) {
csize_t new_total_cap = 0;
for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
const CodeSection* sect = code_section(n);
if (!sect->is_empty()) {
// Compute initial padding; assign it to the previous section,
// even if it's empty (e.g. consts section can be empty).
// Cf. compute_final_layout
csize_t padding = sect->align_at_start(new_total_cap) - new_total_cap;
if (padding != 0) {
new_total_cap += padding;
assert(n - 1 >= SECT_FIRST, "sanity");
new_capacity[n - 1] += padding;
}
}
csize_t exp = sect->size(); // 100% increase
if ((uint)exp < 4*K) exp = 4*K; // minimum initial increase
if (sect == which_cs) {
if (exp < amount) exp = amount;
if (StressCodeBuffers) exp = amount; // expand only slightly
} else if (n == SECT_INSTS) {
// scale down inst increases to a more modest 25%
exp = 4*K + ((exp - 4*K) >> 2);
if (StressCodeBuffers) exp = amount / 2; // expand only slightly
} else if (sect->is_empty()) {
// do not grow an empty secondary section
exp = 0;
}
// Allow for inter-section slop:
exp += CodeSection::end_slop();
csize_t new_cap = sect->size() + exp;
if (new_cap < sect->capacity()) {
// No need to expand after all.
new_cap = sect->capacity();
}
new_capacity[n] = new_cap;
new_total_cap += new_cap;
}
return new_total_cap;
}
void CodeBuffer::expand(CodeSection* which_cs, csize_t amount) {
#ifndef PRODUCT
if (PrintNMethods && (WizardMode || Verbose)) {
tty->print("expanding CodeBuffer:");
this->print();
}
if (StressCodeBuffers && blob() != NULL) {
static int expand_count = 0;
if (expand_count >= 0) expand_count += 1;
if (expand_count > 100 && is_power_of_2(expand_count)) {
tty->print_cr("StressCodeBuffers: have expanded %d times", expand_count);
// simulate an occasional allocation failure:
free_blob();
}
}
#endif //PRODUCT
// Resizing must be allowed
{
if (blob() == NULL) return; // caller must check for blob == NULL
for (int n = 0; n < (int)SECT_LIMIT; n++) {
guarantee(!code_section(n)->is_frozen(), "resizing not allowed when frozen");
}
}
// Figure new capacity for each section.
csize_t new_capacity[SECT_LIMIT];
memset(new_capacity, 0, sizeof(csize_t) * SECT_LIMIT);
csize_t new_total_cap
= figure_expanded_capacities(which_cs, amount, new_capacity);
// Create a new (temporary) code buffer to hold all the new data
CodeBuffer cb(name(), new_total_cap, 0);
if (cb.blob() == NULL) {
// Failed to allocate in code cache.
free_blob();
return;
}
// Create an old code buffer to remember which addresses used to go where.
// This will be useful when we do final assembly into the code cache,
// because we will need to know how to warp any internal address that
// has been created at any time in this CodeBuffer's past.
CodeBuffer* bxp = new CodeBuffer(_total_start, _total_size);
bxp->take_over_code_from(this); // remember the old undersized blob
DEBUG_ONLY(this->_blob = NULL); // silence a later assert
bxp->_before_expand = this->_before_expand;
this->_before_expand = bxp;
// Give each section its required (expanded) capacity.
for (int n = (int)SECT_LIMIT-1; n >= SECT_FIRST; n--) {
CodeSection* cb_sect = cb.code_section(n);
CodeSection* this_sect = code_section(n);
if (new_capacity[n] == 0) continue; // already nulled out
if (n != SECT_INSTS) {
cb.initialize_section_size(cb_sect, new_capacity[n]);
}
assert(cb_sect->capacity() >= new_capacity[n], "big enough");
address cb_start = cb_sect->start();
cb_sect->set_end(cb_start + this_sect->size());
if (this_sect->mark() == NULL) {
cb_sect->clear_mark();
} else {
cb_sect->set_mark(cb_start + this_sect->mark_off());
}
}
// Needs to be initialized when calling fix_relocation_after_move.
cb.blob()->set_ctable_begin(cb.consts()->start());
// Move all the code and relocations to the new blob:
relocate_code_to(&cb);
// Copy the temporary code buffer into the current code buffer.
// Basically, do {*this = cb}, except for some control information.
this->take_over_code_from(&cb);
cb.set_blob(NULL);
// Zap the old code buffer contents, to avoid mistakenly using them.
debug_only(Copy::fill_to_bytes(bxp->_total_start, bxp->_total_size,
badCodeHeapFreeVal));
_decode_begin = NULL; // sanity
// Make certain that the new sections are all snugly inside the new blob.
verify_section_allocation();
#ifndef PRODUCT
if (PrintNMethods && (WizardMode || Verbose)) {
tty->print("expanded CodeBuffer:");
this->print();
}
#endif //PRODUCT
}
void CodeBuffer::take_over_code_from(CodeBuffer* cb) {
// Must already have disposed of the old blob somehow.
assert(blob() == NULL, "must be empty");
// Take the new blob away from cb.
set_blob(cb->blob());
// Take over all the section pointers.
for (int n = 0; n < (int)SECT_LIMIT; n++) {
CodeSection* cb_sect = cb->code_section(n);
CodeSection* this_sect = code_section(n);
this_sect->take_over_code_from(cb_sect);
}
_overflow_arena = cb->_overflow_arena;
// Make sure the old cb won't try to use it or free it.
DEBUG_ONLY(cb->_blob = (BufferBlob*)badAddress);
}
void CodeBuffer::verify_section_allocation() {
address tstart = _total_start;
if (tstart == badAddress) return; // smashed by set_blob(NULL)
address tend = tstart + _total_size;
if (_blob != NULL) {
guarantee(tstart >= _blob->content_begin(), "sanity");
guarantee(tend <= _blob->content_end(), "sanity");
}
// Verify disjointness.
for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
CodeSection* sect = code_section(n);
if (!sect->is_allocated() || sect->is_empty()) continue;
guarantee((intptr_t)sect->start() % sect->alignment() == 0
|| sect->is_empty() || _blob == NULL,
"start is aligned");
for (int m = (int) SECT_FIRST; m < (int) SECT_LIMIT; m++) {
CodeSection* other = code_section(m);
if (!other->is_allocated() || other == sect) continue;
guarantee(!other->contains(sect->start() ), "sanity");
// limit is an exclusive address and can be the start of another
// section.
guarantee(!other->contains(sect->limit() - 1), "sanity");
}
guarantee(sect->end() <= tend, "sanity");
guarantee(sect->end() <= sect->limit(), "sanity");
}
}
void CodeBuffer::log_section_sizes(const char* name) {
if (xtty != NULL) {
ttyLocker ttyl;
// log info about buffer usage
xtty->print_cr("<blob name='%s' size='%d'>", name, _total_size);
for (int n = (int) CodeBuffer::SECT_FIRST; n < (int) CodeBuffer::SECT_LIMIT; n++) {
CodeSection* sect = code_section(n);
if (!sect->is_allocated() || sect->is_empty()) continue;
xtty->print_cr("<sect index='%d' size='" SIZE_FORMAT "' free='" SIZE_FORMAT "'/>",
n, sect->limit() - sect->start(), sect->limit() - sect->end());
}
xtty->print_cr("</blob>");
}
}
#ifndef PRODUCT
void CodeSection::decode() {
Disassembler::decode(start(), end());
}
void CodeBuffer::block_comment(intptr_t offset, const char * comment) {
if (_collect_comments) {
_code_strings.add_comment(offset, comment);
}
}
const char* CodeBuffer::code_string(const char* str) {
return _code_strings.add_string(str);
}
class CodeString: public CHeapObj<mtCode> {
private:
friend class CodeStrings;
const char * _string;
CodeString* _next;
CodeString* _prev;
intptr_t _offset;
~CodeString() {
assert(_next == NULL && _prev == NULL, "wrong interface for freeing list");
os::free((void*)_string);
}
bool is_comment() const { return _offset >= 0; }
public:
CodeString(const char * string, intptr_t offset = -1)
: _next(NULL), _prev(NULL), _offset(offset) {
_string = os::strdup(string, mtCode);
}
const char * string() const { return _string; }
intptr_t offset() const { assert(_offset >= 0, "offset for non comment?"); return _offset; }
CodeString* next() const { return _next; }
void set_next(CodeString* next) {
_next = next;
if (next != NULL) {
next->_prev = this;
}
}
CodeString* first_comment() {
if (is_comment()) {
return this;
} else {
return next_comment();
}
}
CodeString* next_comment() const {
CodeString* s = _next;
while (s != NULL && !s->is_comment()) {
s = s->_next;
}
return s;
}
};
CodeString* CodeStrings::find(intptr_t offset) const {
CodeString* a = _strings->first_comment();
while (a != NULL && a->offset() != offset) {
a = a->next_comment();
}
return a;
}
// Convenience for add_comment.
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