1210 lines
45 KiB
C++
1210 lines
45 KiB
C++
/*
|
|
* Copyright (c) 1999, 2020, 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 "c1/c1_Canonicalizer.hpp"
|
|
#include "c1/c1_Optimizer.hpp"
|
|
#include "c1/c1_ValueMap.hpp"
|
|
#include "c1/c1_ValueSet.inline.hpp"
|
|
#include "c1/c1_ValueStack.hpp"
|
|
#include "memory/resourceArea.hpp"
|
|
#include "utilities/bitMap.inline.hpp"
|
|
#include "compiler/compileLog.hpp"
|
|
|
|
typedef GrowableArray<ValueSet*> ValueSetList;
|
|
|
|
Optimizer::Optimizer(IR* ir) {
|
|
assert(ir->is_valid(), "IR must be valid");
|
|
_ir = ir;
|
|
}
|
|
|
|
class CE_Eliminator: public BlockClosure {
|
|
private:
|
|
IR* _hir;
|
|
int _cee_count; // the number of CEs successfully eliminated
|
|
int _ifop_count; // the number of IfOps successfully simplified
|
|
int _has_substitution;
|
|
|
|
public:
|
|
CE_Eliminator(IR* hir) : _hir(hir), _cee_count(0), _ifop_count(0) {
|
|
_has_substitution = false;
|
|
_hir->iterate_preorder(this);
|
|
if (_has_substitution) {
|
|
// substituted some ifops/phis, so resolve the substitution
|
|
SubstitutionResolver sr(_hir);
|
|
}
|
|
|
|
CompileLog* log = _hir->compilation()->log();
|
|
if (log != NULL)
|
|
log->set_context("optimize name='cee'");
|
|
}
|
|
|
|
~CE_Eliminator() {
|
|
CompileLog* log = _hir->compilation()->log();
|
|
if (log != NULL)
|
|
log->clear_context(); // skip marker if nothing was printed
|
|
}
|
|
|
|
int cee_count() const { return _cee_count; }
|
|
int ifop_count() const { return _ifop_count; }
|
|
|
|
void adjust_exception_edges(BlockBegin* block, BlockBegin* sux) {
|
|
int e = sux->number_of_exception_handlers();
|
|
for (int i = 0; i < e; i++) {
|
|
BlockBegin* xhandler = sux->exception_handler_at(i);
|
|
block->add_exception_handler(xhandler);
|
|
|
|
assert(xhandler->is_predecessor(sux), "missing predecessor");
|
|
if (sux->number_of_preds() == 0) {
|
|
// sux is disconnected from graph so disconnect from exception handlers
|
|
xhandler->remove_predecessor(sux);
|
|
}
|
|
if (!xhandler->is_predecessor(block)) {
|
|
xhandler->add_predecessor(block);
|
|
}
|
|
}
|
|
}
|
|
|
|
virtual void block_do(BlockBegin* block);
|
|
|
|
private:
|
|
Value make_ifop(Value x, Instruction::Condition cond, Value y, Value tval, Value fval);
|
|
};
|
|
|
|
void CE_Eliminator::block_do(BlockBegin* block) {
|
|
// 1) find conditional expression
|
|
// check if block ends with an If
|
|
If* if_ = block->end()->as_If();
|
|
if (if_ == NULL) return;
|
|
|
|
// check if If works on int or object types
|
|
// (we cannot handle If's working on long, float or doubles yet,
|
|
// since IfOp doesn't support them - these If's show up if cmp
|
|
// operations followed by If's are eliminated)
|
|
ValueType* if_type = if_->x()->type();
|
|
if (!if_type->is_int() && !if_type->is_object()) return;
|
|
|
|
BlockBegin* t_block = if_->tsux();
|
|
BlockBegin* f_block = if_->fsux();
|
|
Instruction* t_cur = t_block->next();
|
|
Instruction* f_cur = f_block->next();
|
|
|
|
// one Constant may be present between BlockBegin and BlockEnd
|
|
Value t_const = NULL;
|
|
Value f_const = NULL;
|
|
if (t_cur->as_Constant() != NULL && !t_cur->can_trap()) {
|
|
t_const = t_cur;
|
|
t_cur = t_cur->next();
|
|
}
|
|
if (f_cur->as_Constant() != NULL && !f_cur->can_trap()) {
|
|
f_const = f_cur;
|
|
f_cur = f_cur->next();
|
|
}
|
|
|
|
// check if both branches end with a goto
|
|
Goto* t_goto = t_cur->as_Goto();
|
|
if (t_goto == NULL) return;
|
|
Goto* f_goto = f_cur->as_Goto();
|
|
if (f_goto == NULL) return;
|
|
|
|
// check if both gotos merge into the same block
|
|
BlockBegin* sux = t_goto->default_sux();
|
|
if (sux != f_goto->default_sux()) return;
|
|
|
|
// check if at least one word was pushed on sux_state
|
|
// inlining depths must match
|
|
ValueStack* if_state = if_->state();
|
|
ValueStack* sux_state = sux->state();
|
|
if (if_state->scope()->level() > sux_state->scope()->level()) {
|
|
while (sux_state->scope() != if_state->scope()) {
|
|
if_state = if_state->caller_state();
|
|
assert(if_state != NULL, "states do not match up");
|
|
}
|
|
} else if (if_state->scope()->level() < sux_state->scope()->level()) {
|
|
while (sux_state->scope() != if_state->scope()) {
|
|
sux_state = sux_state->caller_state();
|
|
assert(sux_state != NULL, "states do not match up");
|
|
}
|
|
}
|
|
|
|
if (sux_state->stack_size() <= if_state->stack_size()) return;
|
|
|
|
// check if phi function is present at end of successor stack and that
|
|
// only this phi was pushed on the stack
|
|
Value sux_phi = sux_state->stack_at(if_state->stack_size());
|
|
if (sux_phi == NULL || sux_phi->as_Phi() == NULL || sux_phi->as_Phi()->block() != sux) return;
|
|
if (sux_phi->type()->size() != sux_state->stack_size() - if_state->stack_size()) return;
|
|
|
|
// get the values that were pushed in the true- and false-branch
|
|
Value t_value = t_goto->state()->stack_at(if_state->stack_size());
|
|
Value f_value = f_goto->state()->stack_at(if_state->stack_size());
|
|
|
|
// backend does not support floats
|
|
assert(t_value->type()->base() == f_value->type()->base(), "incompatible types");
|
|
if (t_value->type()->is_float_kind()) return;
|
|
|
|
// check that successor has no other phi functions but sux_phi
|
|
// this can happen when t_block or f_block contained additonal stores to local variables
|
|
// that are no longer represented by explicit instructions
|
|
for_each_phi_fun(sux, phi,
|
|
if (phi != sux_phi) return;
|
|
);
|
|
// true and false blocks can't have phis
|
|
for_each_phi_fun(t_block, phi, return; );
|
|
for_each_phi_fun(f_block, phi, return; );
|
|
|
|
// Only replace safepoint gotos if state_before information is available (if is a safepoint)
|
|
bool is_safepoint = if_->is_safepoint();
|
|
if (!is_safepoint && (t_goto->is_safepoint() || f_goto->is_safepoint())) {
|
|
return;
|
|
}
|
|
|
|
// 2) substitute conditional expression
|
|
// with an IfOp followed by a Goto
|
|
// cut if_ away and get node before
|
|
Instruction* cur_end = if_->prev();
|
|
|
|
// append constants of true- and false-block if necessary
|
|
// clone constants because original block must not be destroyed
|
|
assert((t_value != f_const && f_value != t_const) || t_const == f_const, "mismatch");
|
|
if (t_value == t_const) {
|
|
t_value = new Constant(t_const->type());
|
|
NOT_PRODUCT(t_value->set_printable_bci(if_->printable_bci()));
|
|
cur_end = cur_end->set_next(t_value);
|
|
}
|
|
if (f_value == f_const) {
|
|
f_value = new Constant(f_const->type());
|
|
NOT_PRODUCT(f_value->set_printable_bci(if_->printable_bci()));
|
|
cur_end = cur_end->set_next(f_value);
|
|
}
|
|
|
|
Value result = make_ifop(if_->x(), if_->cond(), if_->y(), t_value, f_value);
|
|
assert(result != NULL, "make_ifop must return a non-null instruction");
|
|
if (!result->is_linked() && result->can_be_linked()) {
|
|
NOT_PRODUCT(result->set_printable_bci(if_->printable_bci()));
|
|
cur_end = cur_end->set_next(result);
|
|
}
|
|
|
|
// append Goto to successor
|
|
ValueStack* state_before = if_->state_before();
|
|
Goto* goto_ = new Goto(sux, state_before, is_safepoint);
|
|
|
|
// prepare state for Goto
|
|
ValueStack* goto_state = if_state;
|
|
goto_state = goto_state->copy(ValueStack::StateAfter, goto_state->bci());
|
|
goto_state->push(result->type(), result);
|
|
assert(goto_state->is_same(sux_state), "states must match now");
|
|
goto_->set_state(goto_state);
|
|
|
|
cur_end = cur_end->set_next(goto_, goto_state->bci());
|
|
|
|
// Adjust control flow graph
|
|
BlockBegin::disconnect_edge(block, t_block);
|
|
BlockBegin::disconnect_edge(block, f_block);
|
|
if (t_block->number_of_preds() == 0) {
|
|
BlockBegin::disconnect_edge(t_block, sux);
|
|
}
|
|
adjust_exception_edges(block, t_block);
|
|
if (f_block->number_of_preds() == 0) {
|
|
BlockBegin::disconnect_edge(f_block, sux);
|
|
}
|
|
adjust_exception_edges(block, f_block);
|
|
|
|
// update block end
|
|
block->set_end(goto_);
|
|
|
|
// substitute the phi if possible
|
|
if (sux_phi->as_Phi()->operand_count() == 1) {
|
|
assert(sux_phi->as_Phi()->operand_at(0) == result, "screwed up phi");
|
|
sux_phi->set_subst(result);
|
|
_has_substitution = true;
|
|
}
|
|
|
|
// 3) successfully eliminated a conditional expression
|
|
_cee_count++;
|
|
if (PrintCEE) {
|
|
tty->print_cr("%d. CEE in B%d (B%d B%d)", cee_count(), block->block_id(), t_block->block_id(), f_block->block_id());
|
|
tty->print_cr("%d. IfOp in B%d", ifop_count(), block->block_id());
|
|
}
|
|
|
|
_hir->verify();
|
|
}
|
|
|
|
Value CE_Eliminator::make_ifop(Value x, Instruction::Condition cond, Value y, Value tval, Value fval) {
|
|
if (!OptimizeIfOps) {
|
|
return new IfOp(x, cond, y, tval, fval);
|
|
}
|
|
|
|
tval = tval->subst();
|
|
fval = fval->subst();
|
|
if (tval == fval) {
|
|
_ifop_count++;
|
|
return tval;
|
|
}
|
|
|
|
x = x->subst();
|
|
y = y->subst();
|
|
|
|
Constant* y_const = y->as_Constant();
|
|
if (y_const != NULL) {
|
|
IfOp* x_ifop = x->as_IfOp();
|
|
if (x_ifop != NULL) { // x is an ifop, y is a constant
|
|
Constant* x_tval_const = x_ifop->tval()->subst()->as_Constant();
|
|
Constant* x_fval_const = x_ifop->fval()->subst()->as_Constant();
|
|
|
|
if (x_tval_const != NULL && x_fval_const != NULL) {
|
|
Instruction::Condition x_ifop_cond = x_ifop->cond();
|
|
|
|
Constant::CompareResult t_compare_res = x_tval_const->compare(cond, y_const);
|
|
Constant::CompareResult f_compare_res = x_fval_const->compare(cond, y_const);
|
|
|
|
// not_comparable here is a valid return in case we're comparing unloaded oop constants
|
|
if (t_compare_res != Constant::not_comparable && f_compare_res != Constant::not_comparable) {
|
|
Value new_tval = t_compare_res == Constant::cond_true ? tval : fval;
|
|
Value new_fval = f_compare_res == Constant::cond_true ? tval : fval;
|
|
|
|
_ifop_count++;
|
|
if (new_tval == new_fval) {
|
|
return new_tval;
|
|
} else {
|
|
return new IfOp(x_ifop->x(), x_ifop_cond, x_ifop->y(), new_tval, new_fval);
|
|
}
|
|
}
|
|
}
|
|
} else {
|
|
Constant* x_const = x->as_Constant();
|
|
if (x_const != NULL) { // x and y are constants
|
|
Constant::CompareResult x_compare_res = x_const->compare(cond, y_const);
|
|
// not_comparable here is a valid return in case we're comparing unloaded oop constants
|
|
if (x_compare_res != Constant::not_comparable) {
|
|
_ifop_count++;
|
|
return x_compare_res == Constant::cond_true ? tval : fval;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return new IfOp(x, cond, y, tval, fval);
|
|
}
|
|
|
|
void Optimizer::eliminate_conditional_expressions() {
|
|
// find conditional expressions & replace them with IfOps
|
|
CE_Eliminator ce(ir());
|
|
}
|
|
|
|
class BlockMerger: public BlockClosure {
|
|
private:
|
|
IR* _hir;
|
|
int _merge_count; // the number of block pairs successfully merged
|
|
|
|
public:
|
|
BlockMerger(IR* hir)
|
|
: _hir(hir)
|
|
, _merge_count(0)
|
|
{
|
|
_hir->iterate_preorder(this);
|
|
CompileLog* log = _hir->compilation()->log();
|
|
if (log != NULL)
|
|
log->set_context("optimize name='eliminate_blocks'");
|
|
}
|
|
|
|
~BlockMerger() {
|
|
CompileLog* log = _hir->compilation()->log();
|
|
if (log != NULL)
|
|
log->clear_context(); // skip marker if nothing was printed
|
|
}
|
|
|
|
bool try_merge(BlockBegin* block) {
|
|
BlockEnd* end = block->end();
|
|
if (end->as_Goto() != NULL) {
|
|
assert(end->number_of_sux() == 1, "end must have exactly one successor");
|
|
// Note: It would be sufficient to check for the number of successors (= 1)
|
|
// in order to decide if this block can be merged potentially. That
|
|
// would then also include switch statements w/ only a default case.
|
|
// However, in that case we would need to make sure the switch tag
|
|
// expression is executed if it can produce observable side effects.
|
|
// We should probably have the canonicalizer simplifying such switch
|
|
// statements and then we are sure we don't miss these merge opportunities
|
|
// here (was bug - gri 7/7/99).
|
|
BlockBegin* sux = end->default_sux();
|
|
if (sux->number_of_preds() == 1 && !sux->is_entry_block() && !end->is_safepoint()) {
|
|
// merge the two blocks
|
|
|
|
#ifdef ASSERT
|
|
// verify that state at the end of block and at the beginning of sux are equal
|
|
// no phi functions must be present at beginning of sux
|
|
ValueStack* sux_state = sux->state();
|
|
ValueStack* end_state = end->state();
|
|
|
|
assert(end_state->scope() == sux_state->scope(), "scopes must match");
|
|
assert(end_state->stack_size() == sux_state->stack_size(), "stack not equal");
|
|
assert(end_state->locals_size() == sux_state->locals_size(), "locals not equal");
|
|
|
|
int index;
|
|
Value sux_value;
|
|
for_each_stack_value(sux_state, index, sux_value) {
|
|
assert(sux_value == end_state->stack_at(index), "stack not equal");
|
|
}
|
|
for_each_local_value(sux_state, index, sux_value) {
|
|
Phi* sux_phi = sux_value->as_Phi();
|
|
if (sux_phi != NULL && sux_phi->is_illegal()) continue;
|
|
assert(sux_value == end_state->local_at(index), "locals not equal");
|
|
}
|
|
assert(sux_state->caller_state() == end_state->caller_state(), "caller not equal");
|
|
#endif
|
|
|
|
// find instruction before end & append first instruction of sux block
|
|
Instruction* prev = end->prev();
|
|
Instruction* next = sux->next();
|
|
assert(prev->as_BlockEnd() == NULL, "must not be a BlockEnd");
|
|
prev->set_next(next);
|
|
prev->fixup_block_pointers();
|
|
sux->disconnect_from_graph();
|
|
block->set_end(sux->end());
|
|
// add exception handlers of deleted block, if any
|
|
for (int k = 0; k < sux->number_of_exception_handlers(); k++) {
|
|
BlockBegin* xhandler = sux->exception_handler_at(k);
|
|
block->add_exception_handler(xhandler);
|
|
|
|
// also substitute predecessor of exception handler
|
|
assert(xhandler->is_predecessor(sux), "missing predecessor");
|
|
xhandler->remove_predecessor(sux);
|
|
if (!xhandler->is_predecessor(block)) {
|
|
xhandler->add_predecessor(block);
|
|
}
|
|
}
|
|
|
|
// debugging output
|
|
_merge_count++;
|
|
if (PrintBlockElimination) {
|
|
tty->print_cr("%d. merged B%d & B%d (stack size = %d)",
|
|
_merge_count, block->block_id(), sux->block_id(), sux->state()->stack_size());
|
|
}
|
|
|
|
_hir->verify();
|
|
|
|
If* if_ = block->end()->as_If();
|
|
if (if_) {
|
|
IfOp* ifop = if_->x()->as_IfOp();
|
|
Constant* con = if_->y()->as_Constant();
|
|
bool swapped = false;
|
|
if (!con || !ifop) {
|
|
ifop = if_->y()->as_IfOp();
|
|
con = if_->x()->as_Constant();
|
|
swapped = true;
|
|
}
|
|
if (con && ifop) {
|
|
Constant* tval = ifop->tval()->as_Constant();
|
|
Constant* fval = ifop->fval()->as_Constant();
|
|
if (tval && fval) {
|
|
// Find the instruction before if_, starting with ifop.
|
|
// When if_ and ifop are not in the same block, prev
|
|
// becomes NULL In such (rare) cases it is not
|
|
// profitable to perform the optimization.
|
|
Value prev = ifop;
|
|
while (prev != NULL && prev->next() != if_) {
|
|
prev = prev->next();
|
|
}
|
|
|
|
if (prev != NULL) {
|
|
Instruction::Condition cond = if_->cond();
|
|
BlockBegin* tsux = if_->tsux();
|
|
BlockBegin* fsux = if_->fsux();
|
|
if (swapped) {
|
|
cond = Instruction::mirror(cond);
|
|
}
|
|
|
|
BlockBegin* tblock = tval->compare(cond, con, tsux, fsux);
|
|
BlockBegin* fblock = fval->compare(cond, con, tsux, fsux);
|
|
if (tblock != fblock && !if_->is_safepoint()) {
|
|
If* newif = new If(ifop->x(), ifop->cond(), false, ifop->y(),
|
|
tblock, fblock, if_->state_before(), if_->is_safepoint());
|
|
newif->set_state(if_->state()->copy());
|
|
|
|
assert(prev->next() == if_, "must be guaranteed by above search");
|
|
NOT_PRODUCT(newif->set_printable_bci(if_->printable_bci()));
|
|
prev->set_next(newif);
|
|
block->set_end(newif);
|
|
|
|
_merge_count++;
|
|
if (PrintBlockElimination) {
|
|
tty->print_cr("%d. replaced If and IfOp at end of B%d with single If", _merge_count, block->block_id());
|
|
}
|
|
|
|
_hir->verify();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
virtual void block_do(BlockBegin* block) {
|
|
_hir->verify();
|
|
// repeat since the same block may merge again
|
|
while (try_merge(block)) {
|
|
_hir->verify();
|
|
}
|
|
}
|
|
};
|
|
|
|
|
|
void Optimizer::eliminate_blocks() {
|
|
// merge blocks if possible
|
|
BlockMerger bm(ir());
|
|
}
|
|
|
|
|
|
class NullCheckEliminator;
|
|
class NullCheckVisitor: public InstructionVisitor {
|
|
private:
|
|
NullCheckEliminator* _nce;
|
|
NullCheckEliminator* nce() { return _nce; }
|
|
|
|
public:
|
|
NullCheckVisitor() {}
|
|
|
|
void set_eliminator(NullCheckEliminator* nce) { _nce = nce; }
|
|
|
|
void do_Phi (Phi* x);
|
|
void do_Local (Local* x);
|
|
void do_Constant (Constant* x);
|
|
void do_LoadField (LoadField* x);
|
|
void do_StoreField (StoreField* x);
|
|
void do_ArrayLength (ArrayLength* x);
|
|
void do_LoadIndexed (LoadIndexed* x);
|
|
void do_StoreIndexed (StoreIndexed* x);
|
|
void do_NegateOp (NegateOp* x);
|
|
void do_ArithmeticOp (ArithmeticOp* x);
|
|
void do_ShiftOp (ShiftOp* x);
|
|
void do_LogicOp (LogicOp* x);
|
|
void do_CompareOp (CompareOp* x);
|
|
void do_IfOp (IfOp* x);
|
|
void do_Convert (Convert* x);
|
|
void do_NullCheck (NullCheck* x);
|
|
void do_TypeCast (TypeCast* x);
|
|
void do_Invoke (Invoke* x);
|
|
void do_NewInstance (NewInstance* x);
|
|
void do_NewTypeArray (NewTypeArray* x);
|
|
void do_NewObjectArray (NewObjectArray* x);
|
|
void do_NewMultiArray (NewMultiArray* x);
|
|
void do_CheckCast (CheckCast* x);
|
|
void do_InstanceOf (InstanceOf* x);
|
|
void do_MonitorEnter (MonitorEnter* x);
|
|
void do_MonitorExit (MonitorExit* x);
|
|
void do_Intrinsic (Intrinsic* x);
|
|
void do_BlockBegin (BlockBegin* x);
|
|
void do_Goto (Goto* x);
|
|
void do_If (If* x);
|
|
void do_IfInstanceOf (IfInstanceOf* x);
|
|
void do_TableSwitch (TableSwitch* x);
|
|
void do_LookupSwitch (LookupSwitch* x);
|
|
void do_Return (Return* x);
|
|
void do_Throw (Throw* x);
|
|
void do_Base (Base* x);
|
|
void do_OsrEntry (OsrEntry* x);
|
|
void do_ExceptionObject(ExceptionObject* x);
|
|
void do_RoundFP (RoundFP* x);
|
|
void do_UnsafeGetRaw (UnsafeGetRaw* x);
|
|
void do_UnsafePutRaw (UnsafePutRaw* x);
|
|
void do_UnsafeGetObject(UnsafeGetObject* x);
|
|
void do_UnsafePutObject(UnsafePutObject* x);
|
|
void do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x);
|
|
void do_ProfileCall (ProfileCall* x);
|
|
void do_ProfileReturnType (ProfileReturnType* x);
|
|
void do_ProfileInvoke (ProfileInvoke* x);
|
|
void do_RuntimeCall (RuntimeCall* x);
|
|
void do_MemBar (MemBar* x);
|
|
void do_RangeCheckPredicate(RangeCheckPredicate* x);
|
|
#ifdef ASSERT
|
|
void do_Assert (Assert* x);
|
|
#endif
|
|
};
|
|
|
|
|
|
// Because of a static contained within (for the purpose of iteration
|
|
// over instructions), it is only valid to have one of these active at
|
|
// a time
|
|
class NullCheckEliminator: public ValueVisitor {
|
|
private:
|
|
Optimizer* _opt;
|
|
|
|
ValueSet* _visitable_instructions; // Visit each instruction only once per basic block
|
|
BlockList* _work_list; // Basic blocks to visit
|
|
|
|
bool visitable(Value x) {
|
|
assert(_visitable_instructions != NULL, "check");
|
|
return _visitable_instructions->contains(x);
|
|
}
|
|
void mark_visited(Value x) {
|
|
assert(_visitable_instructions != NULL, "check");
|
|
_visitable_instructions->remove(x);
|
|
}
|
|
void mark_visitable(Value x) {
|
|
assert(_visitable_instructions != NULL, "check");
|
|
_visitable_instructions->put(x);
|
|
}
|
|
void clear_visitable_state() {
|
|
assert(_visitable_instructions != NULL, "check");
|
|
_visitable_instructions->clear();
|
|
}
|
|
|
|
ValueSet* _set; // current state, propagated to subsequent BlockBegins
|
|
ValueSetList _block_states; // BlockBegin null-check states for all processed blocks
|
|
NullCheckVisitor _visitor;
|
|
NullCheck* _last_explicit_null_check;
|
|
|
|
bool set_contains(Value x) { assert(_set != NULL, "check"); return _set->contains(x); }
|
|
void set_put (Value x) { assert(_set != NULL, "check"); _set->put(x); }
|
|
void set_remove (Value x) { assert(_set != NULL, "check"); _set->remove(x); }
|
|
|
|
BlockList* work_list() { return _work_list; }
|
|
|
|
void iterate_all();
|
|
void iterate_one(BlockBegin* block);
|
|
|
|
ValueSet* state() { return _set; }
|
|
void set_state_from (ValueSet* state) { _set->set_from(state); }
|
|
ValueSet* state_for (BlockBegin* block) { return _block_states.at(block->block_id()); }
|
|
void set_state_for (BlockBegin* block, ValueSet* stack) { _block_states.at_put(block->block_id(), stack); }
|
|
// Returns true if caused a change in the block's state.
|
|
bool merge_state_for(BlockBegin* block,
|
|
ValueSet* incoming_state);
|
|
|
|
public:
|
|
// constructor
|
|
NullCheckEliminator(Optimizer* opt)
|
|
: _opt(opt)
|
|
, _work_list(new BlockList())
|
|
, _set(new ValueSet())
|
|
, _block_states(BlockBegin::number_of_blocks(), BlockBegin::number_of_blocks(), NULL)
|
|
, _last_explicit_null_check(NULL) {
|
|
_visitable_instructions = new ValueSet();
|
|
_visitor.set_eliminator(this);
|
|
CompileLog* log = _opt->ir()->compilation()->log();
|
|
if (log != NULL)
|
|
log->set_context("optimize name='null_check_elimination'");
|
|
}
|
|
|
|
~NullCheckEliminator() {
|
|
CompileLog* log = _opt->ir()->compilation()->log();
|
|
if (log != NULL)
|
|
log->clear_context(); // skip marker if nothing was printed
|
|
}
|
|
|
|
Optimizer* opt() { return _opt; }
|
|
IR* ir () { return opt()->ir(); }
|
|
|
|
// Process a graph
|
|
void iterate(BlockBegin* root);
|
|
|
|
void visit(Value* f);
|
|
|
|
// In some situations (like NullCheck(x); getfield(x)) the debug
|
|
// information from the explicit NullCheck can be used to populate
|
|
// the getfield, even if the two instructions are in different
|
|
// scopes; this allows implicit null checks to be used but the
|
|
// correct exception information to be generated. We must clear the
|
|
// last-traversed NullCheck when we reach a potentially-exception-
|
|
// throwing instruction, as well as in some other cases.
|
|
void set_last_explicit_null_check(NullCheck* check) { _last_explicit_null_check = check; }
|
|
NullCheck* last_explicit_null_check() { return _last_explicit_null_check; }
|
|
Value last_explicit_null_check_obj() { return (_last_explicit_null_check
|
|
? _last_explicit_null_check->obj()
|
|
: NULL); }
|
|
NullCheck* consume_last_explicit_null_check() {
|
|
_last_explicit_null_check->unpin(Instruction::PinExplicitNullCheck);
|
|
_last_explicit_null_check->set_can_trap(false);
|
|
return _last_explicit_null_check;
|
|
}
|
|
void clear_last_explicit_null_check() { _last_explicit_null_check = NULL; }
|
|
|
|
// Handlers for relevant instructions
|
|
// (separated out from NullCheckVisitor for clarity)
|
|
|
|
// The basic contract is that these must leave the instruction in
|
|
// the desired state; must not assume anything about the state of
|
|
// the instruction. We make multiple passes over some basic blocks
|
|
// and the last pass is the only one whose result is valid.
|
|
void handle_AccessField (AccessField* x);
|
|
void handle_ArrayLength (ArrayLength* x);
|
|
void handle_LoadIndexed (LoadIndexed* x);
|
|
void handle_StoreIndexed (StoreIndexed* x);
|
|
void handle_NullCheck (NullCheck* x);
|
|
void handle_Invoke (Invoke* x);
|
|
void handle_NewInstance (NewInstance* x);
|
|
void handle_NewArray (NewArray* x);
|
|
void handle_AccessMonitor (AccessMonitor* x);
|
|
void handle_Intrinsic (Intrinsic* x);
|
|
void handle_ExceptionObject (ExceptionObject* x);
|
|
void handle_Phi (Phi* x);
|
|
void handle_ProfileCall (ProfileCall* x);
|
|
void handle_ProfileReturnType (ProfileReturnType* x);
|
|
};
|
|
|
|
|
|
// NEEDS_CLEANUP
|
|
// There may be other instructions which need to clear the last
|
|
// explicit null check. Anything across which we can not hoist the
|
|
// debug information for a NullCheck instruction must clear it. It
|
|
// might be safer to pattern match "NullCheck ; {AccessField,
|
|
// ArrayLength, LoadIndexed}" but it is more easily structured this way.
|
|
// Should test to see performance hit of clearing it for all handlers
|
|
// with empty bodies below. If it is negligible then we should leave
|
|
// that in for safety, otherwise should think more about it.
|
|
void NullCheckVisitor::do_Phi (Phi* x) { nce()->handle_Phi(x); }
|
|
void NullCheckVisitor::do_Local (Local* x) {}
|
|
void NullCheckVisitor::do_Constant (Constant* x) { /* FIXME: handle object constants */ }
|
|
void NullCheckVisitor::do_LoadField (LoadField* x) { nce()->handle_AccessField(x); }
|
|
void NullCheckVisitor::do_StoreField (StoreField* x) { nce()->handle_AccessField(x); }
|
|
void NullCheckVisitor::do_ArrayLength (ArrayLength* x) { nce()->handle_ArrayLength(x); }
|
|
void NullCheckVisitor::do_LoadIndexed (LoadIndexed* x) { nce()->handle_LoadIndexed(x); }
|
|
void NullCheckVisitor::do_StoreIndexed (StoreIndexed* x) { nce()->handle_StoreIndexed(x); }
|
|
void NullCheckVisitor::do_NegateOp (NegateOp* x) {}
|
|
void NullCheckVisitor::do_ArithmeticOp (ArithmeticOp* x) { if (x->can_trap()) nce()->clear_last_explicit_null_check(); }
|
|
void NullCheckVisitor::do_ShiftOp (ShiftOp* x) {}
|
|
void NullCheckVisitor::do_LogicOp (LogicOp* x) {}
|
|
void NullCheckVisitor::do_CompareOp (CompareOp* x) {}
|
|
void NullCheckVisitor::do_IfOp (IfOp* x) {}
|
|
void NullCheckVisitor::do_Convert (Convert* x) {}
|
|
void NullCheckVisitor::do_NullCheck (NullCheck* x) { nce()->handle_NullCheck(x); }
|
|
void NullCheckVisitor::do_TypeCast (TypeCast* x) {}
|
|
void NullCheckVisitor::do_Invoke (Invoke* x) { nce()->handle_Invoke(x); }
|
|
void NullCheckVisitor::do_NewInstance (NewInstance* x) { nce()->handle_NewInstance(x); }
|
|
void NullCheckVisitor::do_NewTypeArray (NewTypeArray* x) { nce()->handle_NewArray(x); }
|
|
void NullCheckVisitor::do_NewObjectArray (NewObjectArray* x) { nce()->handle_NewArray(x); }
|
|
void NullCheckVisitor::do_NewMultiArray (NewMultiArray* x) { nce()->handle_NewArray(x); }
|
|
void NullCheckVisitor::do_CheckCast (CheckCast* x) { nce()->clear_last_explicit_null_check(); }
|
|
void NullCheckVisitor::do_InstanceOf (InstanceOf* x) {}
|
|
void NullCheckVisitor::do_MonitorEnter (MonitorEnter* x) { nce()->handle_AccessMonitor(x); }
|
|
void NullCheckVisitor::do_MonitorExit (MonitorExit* x) { nce()->handle_AccessMonitor(x); }
|
|
void NullCheckVisitor::do_Intrinsic (Intrinsic* x) { nce()->handle_Intrinsic(x); }
|
|
void NullCheckVisitor::do_BlockBegin (BlockBegin* x) {}
|
|
void NullCheckVisitor::do_Goto (Goto* x) {}
|
|
void NullCheckVisitor::do_If (If* x) {}
|
|
void NullCheckVisitor::do_IfInstanceOf (IfInstanceOf* x) {}
|
|
void NullCheckVisitor::do_TableSwitch (TableSwitch* x) {}
|
|
void NullCheckVisitor::do_LookupSwitch (LookupSwitch* x) {}
|
|
void NullCheckVisitor::do_Return (Return* x) {}
|
|
void NullCheckVisitor::do_Throw (Throw* x) { nce()->clear_last_explicit_null_check(); }
|
|
void NullCheckVisitor::do_Base (Base* x) {}
|
|
void NullCheckVisitor::do_OsrEntry (OsrEntry* x) {}
|
|
void NullCheckVisitor::do_ExceptionObject(ExceptionObject* x) { nce()->handle_ExceptionObject(x); }
|
|
void NullCheckVisitor::do_RoundFP (RoundFP* x) {}
|
|
void NullCheckVisitor::do_UnsafeGetRaw (UnsafeGetRaw* x) {}
|
|
void NullCheckVisitor::do_UnsafePutRaw (UnsafePutRaw* x) {}
|
|
void NullCheckVisitor::do_UnsafeGetObject(UnsafeGetObject* x) {}
|
|
void NullCheckVisitor::do_UnsafePutObject(UnsafePutObject* x) {}
|
|
void NullCheckVisitor::do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x) {}
|
|
void NullCheckVisitor::do_ProfileCall (ProfileCall* x) { nce()->clear_last_explicit_null_check();
|
|
nce()->handle_ProfileCall(x); }
|
|
void NullCheckVisitor::do_ProfileReturnType (ProfileReturnType* x) { nce()->handle_ProfileReturnType(x); }
|
|
void NullCheckVisitor::do_ProfileInvoke (ProfileInvoke* x) {}
|
|
void NullCheckVisitor::do_RuntimeCall (RuntimeCall* x) {}
|
|
void NullCheckVisitor::do_MemBar (MemBar* x) {}
|
|
void NullCheckVisitor::do_RangeCheckPredicate(RangeCheckPredicate* x) {}
|
|
#ifdef ASSERT
|
|
void NullCheckVisitor::do_Assert (Assert* x) {}
|
|
#endif
|
|
|
|
void NullCheckEliminator::visit(Value* p) {
|
|
assert(*p != NULL, "should not find NULL instructions");
|
|
if (visitable(*p)) {
|
|
mark_visited(*p);
|
|
(*p)->visit(&_visitor);
|
|
}
|
|
}
|
|
|
|
bool NullCheckEliminator::merge_state_for(BlockBegin* block, ValueSet* incoming_state) {
|
|
ValueSet* state = state_for(block);
|
|
if (state == NULL) {
|
|
state = incoming_state->copy();
|
|
set_state_for(block, state);
|
|
return true;
|
|
} else {
|
|
bool changed = state->set_intersect(incoming_state);
|
|
if (PrintNullCheckElimination && changed) {
|
|
tty->print_cr("Block %d's null check state changed", block->block_id());
|
|
}
|
|
return changed;
|
|
}
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::iterate_all() {
|
|
while (work_list()->length() > 0) {
|
|
iterate_one(work_list()->pop());
|
|
}
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::iterate_one(BlockBegin* block) {
|
|
clear_visitable_state();
|
|
// clear out an old explicit null checks
|
|
set_last_explicit_null_check(NULL);
|
|
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr(" ...iterating block %d in null check elimination for %s::%s%s",
|
|
block->block_id(),
|
|
ir()->method()->holder()->name()->as_utf8(),
|
|
ir()->method()->name()->as_utf8(),
|
|
ir()->method()->signature()->as_symbol()->as_utf8());
|
|
}
|
|
|
|
// Create new state if none present (only happens at root)
|
|
if (state_for(block) == NULL) {
|
|
ValueSet* tmp_state = new ValueSet();
|
|
set_state_for(block, tmp_state);
|
|
// Initial state is that local 0 (receiver) is non-null for
|
|
// non-static methods
|
|
ValueStack* stack = block->state();
|
|
IRScope* scope = stack->scope();
|
|
ciMethod* method = scope->method();
|
|
if (!method->is_static()) {
|
|
Local* local0 = stack->local_at(0)->as_Local();
|
|
assert(local0 != NULL, "must be");
|
|
assert(local0->type() == objectType, "invalid type of receiver");
|
|
|
|
if (local0 != NULL) {
|
|
// Local 0 is used in this scope
|
|
tmp_state->put(local0);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Local 0 (value %d) proven non-null upon entry", local0->id());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Must copy block's state to avoid mutating it during iteration
|
|
// through the block -- otherwise "not-null" states can accidentally
|
|
// propagate "up" through the block during processing of backward
|
|
// branches and algorithm is incorrect (and does not converge)
|
|
set_state_from(state_for(block));
|
|
|
|
// allow visiting of Phis belonging to this block
|
|
for_each_phi_fun(block, phi,
|
|
mark_visitable(phi);
|
|
);
|
|
|
|
BlockEnd* e = block->end();
|
|
assert(e != NULL, "incomplete graph");
|
|
int i;
|
|
|
|
// Propagate the state before this block into the exception
|
|
// handlers. They aren't true successors since we aren't guaranteed
|
|
// to execute the whole block before executing them. Also putting
|
|
// them on first seems to help reduce the amount of iteration to
|
|
// reach a fixed point.
|
|
for (i = 0; i < block->number_of_exception_handlers(); i++) {
|
|
BlockBegin* next = block->exception_handler_at(i);
|
|
if (merge_state_for(next, state())) {
|
|
if (!work_list()->contains(next)) {
|
|
work_list()->push(next);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Iterate through block, updating state.
|
|
for (Instruction* instr = block; instr != NULL; instr = instr->next()) {
|
|
// Mark instructions in this block as visitable as they are seen
|
|
// in the instruction list. This keeps the iteration from
|
|
// visiting instructions which are references in other blocks or
|
|
// visiting instructions more than once.
|
|
mark_visitable(instr);
|
|
if (instr->is_pinned() || instr->can_trap() || (instr->as_NullCheck() != NULL)) {
|
|
mark_visited(instr);
|
|
instr->input_values_do(this);
|
|
instr->visit(&_visitor);
|
|
}
|
|
}
|
|
|
|
// Propagate state to successors if necessary
|
|
for (i = 0; i < e->number_of_sux(); i++) {
|
|
BlockBegin* next = e->sux_at(i);
|
|
if (merge_state_for(next, state())) {
|
|
if (!work_list()->contains(next)) {
|
|
work_list()->push(next);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::iterate(BlockBegin* block) {
|
|
work_list()->push(block);
|
|
iterate_all();
|
|
}
|
|
|
|
void NullCheckEliminator::handle_AccessField(AccessField* x) {
|
|
if (x->is_static()) {
|
|
if (x->as_LoadField() != NULL) {
|
|
// If the field is a non-null static final object field (as is
|
|
// often the case for sun.misc.Unsafe), put this LoadField into
|
|
// the non-null map
|
|
ciField* field = x->field();
|
|
if (field->is_constant()) {
|
|
ciConstant field_val = field->constant_value();
|
|
BasicType field_type = field_val.basic_type();
|
|
if (is_reference_type(field_type)) {
|
|
ciObject* obj_val = field_val.as_object();
|
|
if (!obj_val->is_null_object()) {
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("AccessField %d proven non-null by static final non-null oop check",
|
|
x->id());
|
|
}
|
|
set_put(x);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
// Be conservative
|
|
clear_last_explicit_null_check();
|
|
return;
|
|
}
|
|
|
|
Value obj = x->obj();
|
|
if (set_contains(obj)) {
|
|
// Value is non-null => update AccessField
|
|
if (last_explicit_null_check_obj() == obj && !x->needs_patching()) {
|
|
x->set_explicit_null_check(consume_last_explicit_null_check());
|
|
x->set_needs_null_check(true);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Folded NullCheck %d into AccessField %d's null check for value %d",
|
|
x->explicit_null_check()->id(), x->id(), obj->id());
|
|
}
|
|
} else {
|
|
x->set_explicit_null_check(NULL);
|
|
x->set_needs_null_check(false);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Eliminated AccessField %d's null check for value %d", x->id(), obj->id());
|
|
}
|
|
}
|
|
} else {
|
|
set_put(obj);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("AccessField %d of value %d proves value to be non-null", x->id(), obj->id());
|
|
}
|
|
// Ensure previous passes do not cause wrong state
|
|
x->set_needs_null_check(true);
|
|
x->set_explicit_null_check(NULL);
|
|
}
|
|
clear_last_explicit_null_check();
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::handle_ArrayLength(ArrayLength* x) {
|
|
Value array = x->array();
|
|
if (set_contains(array)) {
|
|
// Value is non-null => update AccessArray
|
|
if (last_explicit_null_check_obj() == array) {
|
|
x->set_explicit_null_check(consume_last_explicit_null_check());
|
|
x->set_needs_null_check(true);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Folded NullCheck %d into ArrayLength %d's null check for value %d",
|
|
x->explicit_null_check()->id(), x->id(), array->id());
|
|
}
|
|
} else {
|
|
x->set_explicit_null_check(NULL);
|
|
x->set_needs_null_check(false);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Eliminated ArrayLength %d's null check for value %d", x->id(), array->id());
|
|
}
|
|
}
|
|
} else {
|
|
set_put(array);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("ArrayLength %d of value %d proves value to be non-null", x->id(), array->id());
|
|
}
|
|
// Ensure previous passes do not cause wrong state
|
|
x->set_needs_null_check(true);
|
|
x->set_explicit_null_check(NULL);
|
|
}
|
|
clear_last_explicit_null_check();
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::handle_LoadIndexed(LoadIndexed* x) {
|
|
Value array = x->array();
|
|
if (set_contains(array)) {
|
|
// Value is non-null => update AccessArray
|
|
if (last_explicit_null_check_obj() == array) {
|
|
x->set_explicit_null_check(consume_last_explicit_null_check());
|
|
x->set_needs_null_check(true);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Folded NullCheck %d into LoadIndexed %d's null check for value %d",
|
|
x->explicit_null_check()->id(), x->id(), array->id());
|
|
}
|
|
} else {
|
|
x->set_explicit_null_check(NULL);
|
|
x->set_needs_null_check(false);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Eliminated LoadIndexed %d's null check for value %d", x->id(), array->id());
|
|
}
|
|
}
|
|
} else {
|
|
set_put(array);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("LoadIndexed %d of value %d proves value to be non-null", x->id(), array->id());
|
|
}
|
|
// Ensure previous passes do not cause wrong state
|
|
x->set_needs_null_check(true);
|
|
x->set_explicit_null_check(NULL);
|
|
}
|
|
clear_last_explicit_null_check();
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::handle_StoreIndexed(StoreIndexed* x) {
|
|
Value array = x->array();
|
|
if (set_contains(array)) {
|
|
// Value is non-null => update AccessArray
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Eliminated StoreIndexed %d's null check for value %d", x->id(), array->id());
|
|
}
|
|
x->set_needs_null_check(false);
|
|
} else {
|
|
set_put(array);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("StoreIndexed %d of value %d proves value to be non-null", x->id(), array->id());
|
|
}
|
|
// Ensure previous passes do not cause wrong state
|
|
x->set_needs_null_check(true);
|
|
}
|
|
clear_last_explicit_null_check();
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::handle_NullCheck(NullCheck* x) {
|
|
Value obj = x->obj();
|
|
if (set_contains(obj)) {
|
|
// Already proven to be non-null => this NullCheck is useless
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Eliminated NullCheck %d for value %d", x->id(), obj->id());
|
|
}
|
|
// Don't unpin since that may shrink obj's live range and make it unavailable for debug info.
|
|
// The code generator won't emit LIR for a NullCheck that cannot trap.
|
|
x->set_can_trap(false);
|
|
} else {
|
|
// May be null => add to map and set last explicit NullCheck
|
|
x->set_can_trap(true);
|
|
// make sure it's pinned if it can trap
|
|
x->pin(Instruction::PinExplicitNullCheck);
|
|
set_put(obj);
|
|
set_last_explicit_null_check(x);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("NullCheck %d of value %d proves value to be non-null", x->id(), obj->id());
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::handle_Invoke(Invoke* x) {
|
|
if (!x->has_receiver()) {
|
|
// Be conservative
|
|
clear_last_explicit_null_check();
|
|
return;
|
|
}
|
|
|
|
Value recv = x->receiver();
|
|
if (!set_contains(recv)) {
|
|
set_put(recv);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Invoke %d of value %d proves value to be non-null", x->id(), recv->id());
|
|
}
|
|
}
|
|
clear_last_explicit_null_check();
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::handle_NewInstance(NewInstance* x) {
|
|
set_put(x);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("NewInstance %d is non-null", x->id());
|
|
}
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::handle_NewArray(NewArray* x) {
|
|
set_put(x);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("NewArray %d is non-null", x->id());
|
|
}
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::handle_ExceptionObject(ExceptionObject* x) {
|
|
set_put(x);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("ExceptionObject %d is non-null", x->id());
|
|
}
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::handle_AccessMonitor(AccessMonitor* x) {
|
|
Value obj = x->obj();
|
|
if (set_contains(obj)) {
|
|
// Value is non-null => update AccessMonitor
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Eliminated AccessMonitor %d's null check for value %d", x->id(), obj->id());
|
|
}
|
|
x->set_needs_null_check(false);
|
|
} else {
|
|
set_put(obj);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("AccessMonitor %d of value %d proves value to be non-null", x->id(), obj->id());
|
|
}
|
|
// Ensure previous passes do not cause wrong state
|
|
x->set_needs_null_check(true);
|
|
}
|
|
clear_last_explicit_null_check();
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::handle_Intrinsic(Intrinsic* x) {
|
|
if (!x->has_receiver()) {
|
|
if (x->id() == vmIntrinsics::_arraycopy) {
|
|
for (int i = 0; i < x->number_of_arguments(); i++) {
|
|
x->set_arg_needs_null_check(i, !set_contains(x->argument_at(i)));
|
|
}
|
|
}
|
|
|
|
// Be conservative
|
|
clear_last_explicit_null_check();
|
|
return;
|
|
}
|
|
|
|
Value recv = x->receiver();
|
|
if (set_contains(recv)) {
|
|
// Value is non-null => update Intrinsic
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Eliminated Intrinsic %d's null check for value %d", vmIntrinsics::as_int(x->id()), recv->id());
|
|
}
|
|
x->set_needs_null_check(false);
|
|
} else {
|
|
set_put(recv);
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Intrinsic %d of value %d proves value to be non-null", vmIntrinsics::as_int(x->id()), recv->id());
|
|
}
|
|
// Ensure previous passes do not cause wrong state
|
|
x->set_needs_null_check(true);
|
|
}
|
|
clear_last_explicit_null_check();
|
|
}
|
|
|
|
|
|
void NullCheckEliminator::handle_Phi(Phi* x) {
|
|
int i;
|
|
bool all_non_null = true;
|
|
if (x->is_illegal()) {
|
|
all_non_null = false;
|
|
} else {
|
|
for (i = 0; i < x->operand_count(); i++) {
|
|
Value input = x->operand_at(i);
|
|
if (!set_contains(input)) {
|
|
all_non_null = false;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (all_non_null) {
|
|
// Value is non-null => update Phi
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Eliminated Phi %d's null check for phifun because all inputs are non-null", x->id());
|
|
}
|
|
x->set_needs_null_check(false);
|
|
} else if (set_contains(x)) {
|
|
set_remove(x);
|
|
}
|
|
}
|
|
|
|
void NullCheckEliminator::handle_ProfileCall(ProfileCall* x) {
|
|
for (int i = 0; i < x->nb_profiled_args(); i++) {
|
|
x->set_arg_needs_null_check(i, !set_contains(x->profiled_arg_at(i)));
|
|
}
|
|
}
|
|
|
|
void NullCheckEliminator::handle_ProfileReturnType(ProfileReturnType* x) {
|
|
x->set_needs_null_check(!set_contains(x->ret()));
|
|
}
|
|
|
|
void Optimizer::eliminate_null_checks() {
|
|
ResourceMark rm;
|
|
|
|
NullCheckEliminator nce(this);
|
|
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Starting null check elimination for method %s::%s%s",
|
|
ir()->method()->holder()->name()->as_utf8(),
|
|
ir()->method()->name()->as_utf8(),
|
|
ir()->method()->signature()->as_symbol()->as_utf8());
|
|
}
|
|
|
|
// Apply to graph
|
|
nce.iterate(ir()->start());
|
|
|
|
// walk over the graph looking for exception
|
|
// handlers and iterate over them as well
|
|
int nblocks = BlockBegin::number_of_blocks();
|
|
BlockList blocks(nblocks);
|
|
boolArray visited_block(nblocks, nblocks, false);
|
|
|
|
blocks.push(ir()->start());
|
|
visited_block.at_put(ir()->start()->block_id(), true);
|
|
for (int i = 0; i < blocks.length(); i++) {
|
|
BlockBegin* b = blocks.at(i);
|
|
// exception handlers need to be treated as additional roots
|
|
for (int e = b->number_of_exception_handlers(); e-- > 0; ) {
|
|
BlockBegin* excp = b->exception_handler_at(e);
|
|
int id = excp->block_id();
|
|
if (!visited_block.at(id)) {
|
|
blocks.push(excp);
|
|
visited_block.at_put(id, true);
|
|
nce.iterate(excp);
|
|
}
|
|
}
|
|
// traverse successors
|
|
BlockEnd *end = b->end();
|
|
for (int s = end->number_of_sux(); s-- > 0; ) {
|
|
BlockBegin* next = end->sux_at(s);
|
|
int id = next->block_id();
|
|
if (!visited_block.at(id)) {
|
|
blocks.push(next);
|
|
visited_block.at_put(id, true);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
if (PrintNullCheckElimination) {
|
|
tty->print_cr("Done with null check elimination for method %s::%s%s",
|
|
ir()->method()->holder()->name()->as_utf8(),
|
|
ir()->method()->name()->as_utf8(),
|
|
ir()->method()->signature()->as_symbol()->as_utf8());
|
|
}
|
|
}
|