Java example source code file (loopopts.cpp)
The loopopts.cpp Java example source code/*
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*
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* 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).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
#include "precompiled.hpp"
#include "memory/allocation.inline.hpp"
#include "opto/addnode.hpp"
#include "opto/connode.hpp"
#include "opto/divnode.hpp"
#include "opto/loopnode.hpp"
#include "opto/matcher.hpp"
#include "opto/mulnode.hpp"
#include "opto/rootnode.hpp"
#include "opto/subnode.hpp"
//=============================================================================
//------------------------------split_thru_phi---------------------------------
// Split Node 'n' through merge point if there is enough win.
Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
// ConvI2L may have type information on it which is unsafe to push up
// so disable this for now
return NULL;
}
if (n->is_MathExact()) {
// MathExact has projections that are not correctly handled in the code
// below.
return NULL;
}
int wins = 0;
assert(!n->is_CFG(), "");
assert(region->is_Region(), "");
const Type* type = n->bottom_type();
const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
Node *phi;
if (t_oop != NULL && t_oop->is_known_instance_field()) {
int iid = t_oop->instance_id();
int index = C->get_alias_index(t_oop);
int offset = t_oop->offset();
phi = new (C) PhiNode(region, type, NULL, iid, index, offset);
} else {
phi = PhiNode::make_blank(region, n);
}
uint old_unique = C->unique();
for (uint i = 1; i < region->req(); i++) {
Node *x;
Node* the_clone = NULL;
if (region->in(i) == C->top()) {
x = C->top(); // Dead path? Use a dead data op
} else {
x = n->clone(); // Else clone up the data op
the_clone = x; // Remember for possible deletion.
// Alter data node to use pre-phi inputs
if (n->in(0) == region)
x->set_req( 0, region->in(i) );
for (uint j = 1; j < n->req(); j++) {
Node *in = n->in(j);
if (in->is_Phi() && in->in(0) == region)
x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
}
}
// Check for a 'win' on some paths
const Type *t = x->Value(&_igvn);
bool singleton = t->singleton();
// A TOP singleton indicates that there are no possible values incoming
// along a particular edge. In most cases, this is OK, and the Phi will
// be eliminated later in an Ideal call. However, we can't allow this to
// happen if the singleton occurs on loop entry, as the elimination of
// the PhiNode may cause the resulting node to migrate back to a previous
// loop iteration.
if (singleton && t == Type::TOP) {
// Is_Loop() == false does not confirm the absence of a loop (e.g., an
// irreducible loop may not be indicated by an affirmative is_Loop());
// therefore, the only top we can split thru a phi is on a backedge of
// a loop.
singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
}
if (singleton) {
wins++;
x = ((PhaseGVN&)_igvn).makecon(t);
} else {
// We now call Identity to try to simplify the cloned node.
// Note that some Identity methods call phase->type(this).
// Make sure that the type array is big enough for
// our new node, even though we may throw the node away.
// (Note: This tweaking with igvn only works because x is a new node.)
_igvn.set_type(x, t);
// If x is a TypeNode, capture any more-precise type permanently into Node
// otherwise it will be not updated during igvn->transform since
// igvn->type(x) is set to x->Value() already.
x->raise_bottom_type(t);
Node *y = x->Identity(&_igvn);
if (y != x) {
wins++;
x = y;
} else {
y = _igvn.hash_find(x);
if (y) {
wins++;
x = y;
} else {
// Else x is a new node we are keeping
// We do not need register_new_node_with_optimizer
// because set_type has already been called.
_igvn._worklist.push(x);
}
}
}
if (x != the_clone && the_clone != NULL)
_igvn.remove_dead_node(the_clone);
phi->set_req( i, x );
}
// Too few wins?
if (wins <= policy) {
_igvn.remove_dead_node(phi);
return NULL;
}
// Record Phi
register_new_node( phi, region );
for (uint i2 = 1; i2 < phi->req(); i2++) {
Node *x = phi->in(i2);
// If we commoned up the cloned 'x' with another existing Node,
// the existing Node picks up a new use. We need to make the
// existing Node occur higher up so it dominates its uses.
Node *old_ctrl;
IdealLoopTree *old_loop;
if (x->is_Con()) {
// Constant's control is always root.
set_ctrl(x, C->root());
continue;
}
// The occasional new node
if (x->_idx >= old_unique) { // Found a new, unplaced node?
old_ctrl = NULL;
old_loop = NULL; // Not in any prior loop
} else {
old_ctrl = get_ctrl(x);
old_loop = get_loop(old_ctrl); // Get prior loop
}
// New late point must dominate new use
Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
if (new_ctrl == old_ctrl) // Nothing is changed
continue;
IdealLoopTree *new_loop = get_loop(new_ctrl);
// Don't move x into a loop if its uses are
// outside of loop. Otherwise x will be cloned
// for each use outside of this loop.
IdealLoopTree *use_loop = get_loop(region);
if (!new_loop->is_member(use_loop) &&
(old_loop == NULL || !new_loop->is_member(old_loop))) {
// Take early control, later control will be recalculated
// during next iteration of loop optimizations.
new_ctrl = get_early_ctrl(x);
new_loop = get_loop(new_ctrl);
}
// Set new location
set_ctrl(x, new_ctrl);
// If changing loop bodies, see if we need to collect into new body
if (old_loop != new_loop) {
if (old_loop && !old_loop->_child)
old_loop->_body.yank(x);
if (!new_loop->_child)
new_loop->_body.push(x); // Collect body info
}
}
return phi;
}
//------------------------------dominated_by------------------------------------
// Replace the dominated test with an obvious true or false. Place it on the
// IGVN worklist for later cleanup. Move control-dependent data Nodes on the
// live path up to the dominating control.
void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
#ifndef PRODUCT
if (VerifyLoopOptimizations && PrintOpto) tty->print_cr("dominating test");
#endif
// prevdom is the dominating projection of the dominating test.
assert( iff->is_If(), "" );
assert( iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added");
int pop = prevdom->Opcode();
assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
if (flip) {
if (pop == Op_IfTrue)
pop = Op_IfFalse;
else
pop = Op_IfTrue;
}
// 'con' is set to true or false to kill the dominated test.
Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
set_ctrl(con, C->root()); // Constant gets a new use
// Hack the dominated test
_igvn.replace_input_of(iff, 1, con);
// If I dont have a reachable TRUE and FALSE path following the IfNode then
// I can assume this path reaches an infinite loop. In this case it's not
// important to optimize the data Nodes - either the whole compilation will
// be tossed or this path (and all data Nodes) will go dead.
if (iff->outcnt() != 2) return;
// Make control-dependent data Nodes on the live path (path that will remain
// once the dominated IF is removed) become control-dependent on the
// dominating projection.
Node* dp = iff->as_If()->proj_out(pop == Op_IfTrue);
// Loop predicates may have depending checks which should not
// be skipped. For example, range check predicate has two checks
// for lower and upper bounds.
if (dp == NULL)
return;
ProjNode* dp_proj = dp->as_Proj();
ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
if (exclude_loop_predicate &&
unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate))
return; // Let IGVN transformation change control dependence.
IdealLoopTree *old_loop = get_loop(dp);
for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
Node* cd = dp->fast_out(i); // Control-dependent node
if (cd->depends_only_on_test()) {
assert(cd->in(0) == dp, "");
_igvn.replace_input_of(cd, 0, prevdom);
set_early_ctrl(cd);
IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
if (old_loop != new_loop) {
if (!old_loop->_child) old_loop->_body.yank(cd);
if (!new_loop->_child) new_loop->_body.push(cd);
}
--i;
--imax;
}
}
}
//------------------------------has_local_phi_input----------------------------
// Return TRUE if 'n' has Phi inputs from its local block and no other
// block-local inputs (all non-local-phi inputs come from earlier blocks)
Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
Node *n_ctrl = get_ctrl(n);
// See if some inputs come from a Phi in this block, or from before
// this block.
uint i;
for( i = 1; i < n->req(); i++ ) {
Node *phi = n->in(i);
if( phi->is_Phi() && phi->in(0) == n_ctrl )
break;
}
if( i >= n->req() )
return NULL; // No Phi inputs; nowhere to clone thru
// Check for inputs created between 'n' and the Phi input. These
// must split as well; they have already been given the chance
// (courtesy of a post-order visit) and since they did not we must
// recover the 'cost' of splitting them by being very profitable
// when splitting 'n'. Since this is unlikely we simply give up.
for( i = 1; i < n->req(); i++ ) {
Node *m = n->in(i);
if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
// We allow the special case of AddP's with no local inputs.
// This allows us to split-up address expressions.
if (m->is_AddP() &&
get_ctrl(m->in(2)) != n_ctrl &&
get_ctrl(m->in(3)) != n_ctrl) {
// Move the AddP up to dominating point
set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
continue;
}
return NULL;
}
}
return n_ctrl;
}
//------------------------------remix_address_expressions----------------------
// Rework addressing expressions to get the most loop-invariant stuff
// moved out. We'd like to do all associative operators, but it's especially
// important (common) to do address expressions.
Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
if (!has_ctrl(n)) return NULL;
Node *n_ctrl = get_ctrl(n);
IdealLoopTree *n_loop = get_loop(n_ctrl);
// See if 'n' mixes loop-varying and loop-invariant inputs and
// itself is loop-varying.
// Only interested in binary ops (and AddP)
if( n->req() < 3 || n->req() > 4 ) return NULL;
Node *n1_ctrl = get_ctrl(n->in( 1));
Node *n2_ctrl = get_ctrl(n->in( 2));
Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
IdealLoopTree *n1_loop = get_loop( n1_ctrl );
IdealLoopTree *n2_loop = get_loop( n2_ctrl );
IdealLoopTree *n3_loop = get_loop( n3_ctrl );
// Does one of my inputs spin in a tighter loop than self?
if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
(n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
(n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
return NULL; // Leave well enough alone
// Is at least one of my inputs loop-invariant?
if( n1_loop == n_loop &&
n2_loop == n_loop &&
n3_loop == n_loop )
return NULL; // No loop-invariant inputs
int n_op = n->Opcode();
// Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
if( n_op == Op_LShiftI ) {
// Scale is loop invariant
Node *scale = n->in(2);
Node *scale_ctrl = get_ctrl(scale);
IdealLoopTree *scale_loop = get_loop(scale_ctrl );
if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
return NULL;
const TypeInt *scale_t = scale->bottom_type()->isa_int();
if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
return NULL; // Dont bother with byte/short masking
// Add must vary with loop (else shift would be loop-invariant)
Node *add = n->in(1);
Node *add_ctrl = get_ctrl(add);
IdealLoopTree *add_loop = get_loop(add_ctrl);
//assert( n_loop == add_loop, "" );
if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
// Convert I-V into I+ (0-V); same for V-I
if( add->Opcode() == Op_SubI &&
_igvn.type( add->in(1) ) != TypeInt::ZERO ) {
Node *zero = _igvn.intcon(0);
set_ctrl(zero, C->root());
Node *neg = new (C) SubINode( _igvn.intcon(0), add->in(2) );
register_new_node( neg, get_ctrl(add->in(2) ) );
add = new (C) AddINode( add->in(1), neg );
register_new_node( add, add_ctrl );
}
if( add->Opcode() != Op_AddI ) return NULL;
// See if one add input is loop invariant
Node *add_var = add->in(1);
Node *add_var_ctrl = get_ctrl(add_var);
IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
Node *add_invar = add->in(2);
Node *add_invar_ctrl = get_ctrl(add_invar);
IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
if( add_var_loop == n_loop ) {
} else if( add_invar_loop == n_loop ) {
// Swap to find the invariant part
add_invar = add_var;
add_invar_ctrl = add_var_ctrl;
add_invar_loop = add_var_loop;
add_var = add->in(2);
Node *add_var_ctrl = get_ctrl(add_var);
IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
} else // Else neither input is loop invariant
return NULL;
if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
return NULL; // No invariant part of the add?
// Yes! Reshape address expression!
Node *inv_scale = new (C) LShiftINode( add_invar, scale );
Node *inv_scale_ctrl =
dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
add_invar_ctrl : scale_ctrl;
register_new_node( inv_scale, inv_scale_ctrl );
Node *var_scale = new (C) LShiftINode( add_var, scale );
register_new_node( var_scale, n_ctrl );
Node *var_add = new (C) AddINode( var_scale, inv_scale );
register_new_node( var_add, n_ctrl );
_igvn.replace_node( n, var_add );
return var_add;
}
// Replace (I+V) with (V+I)
if( n_op == Op_AddI ||
n_op == Op_AddL ||
n_op == Op_AddF ||
n_op == Op_AddD ||
n_op == Op_MulI ||
n_op == Op_MulL ||
n_op == Op_MulF ||
n_op == Op_MulD ) {
if( n2_loop == n_loop ) {
assert( n1_loop != n_loop, "" );
n->swap_edges(1, 2);
}
}
// Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
// but not if I2 is a constant.
if( n_op == Op_AddP ) {
if( n2_loop == n_loop && n3_loop != n_loop ) {
if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
IdealLoopTree *n22loop = get_loop( n22_ctrl );
IdealLoopTree *n23_loop = get_loop( n23_ctrl );
if( n22loop != n_loop && n22loop->is_member(n_loop) &&
n23_loop == n_loop ) {
Node *add1 = new (C) AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
// Stuff new AddP in the loop preheader
register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
Node *add2 = new (C) AddPNode( n->in(1), add1, n->in(2)->in(3) );
register_new_node( add2, n_ctrl );
_igvn.replace_node( n, add2 );
return add2;
}
}
}
// Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
if( n2_loop != n_loop && n3_loop == n_loop ) {
if( n->in(3)->Opcode() == Op_AddI ) {
Node *V = n->in(3)->in(1);
Node *I = n->in(3)->in(2);
if( is_member(n_loop,get_ctrl(V)) ) {
} else {
Node *tmp = V; V = I; I = tmp;
}
if( !is_member(n_loop,get_ctrl(I)) ) {
Node *add1 = new (C) AddPNode( n->in(1), n->in(2), I );
// Stuff new AddP in the loop preheader
register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
Node *add2 = new (C) AddPNode( n->in(1), add1, V );
register_new_node( add2, n_ctrl );
_igvn.replace_node( n, add2 );
return add2;
}
}
}
}
return NULL;
}
//------------------------------conditional_move-------------------------------
// Attempt to replace a Phi with a conditional move. We have some pretty
// strict profitability requirements. All Phis at the merge point must
// be converted, so we can remove the control flow. We need to limit the
// number of c-moves to a small handful. All code that was in the side-arms
// of the CFG diamond is now speculatively executed. This code has to be
// "cheap enough". We are pretty much limited to CFG diamonds that merge
// 1 or 2 items with a total of 1 or 2 ops executed speculatively.
Node *PhaseIdealLoop::conditional_move( Node *region ) {
assert(region->is_Region(), "sanity check");
if (region->req() != 3) return NULL;
// Check for CFG diamond
Node *lp = region->in(1);
Node *rp = region->in(2);
if (!lp || !rp) return NULL;
Node *lp_c = lp->in(0);
if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
IfNode *iff = lp_c->as_If();
// Check for ops pinned in an arm of the diamond.
// Can't remove the control flow in this case
if (lp->outcnt() > 1) return NULL;
if (rp->outcnt() > 1) return NULL;
IdealLoopTree* r_loop = get_loop(region);
assert(r_loop == get_loop(iff), "sanity");
// Always convert to CMOVE if all results are used only outside this loop.
bool used_inside_loop = (r_loop == _ltree_root);
// Check profitability
int cost = 0;
int phis = 0;
for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
Node *out = region->fast_out(i);
if (!out->is_Phi()) continue; // Ignore other control edges, etc
phis++;
PhiNode* phi = out->as_Phi();
BasicType bt = phi->type()->basic_type();
switch (bt) {
case T_FLOAT:
case T_DOUBLE: {
cost += Matcher::float_cmove_cost(); // Could be very expensive
break;
}
case T_LONG: {
cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
}
case T_INT: // These all CMOV fine
case T_ADDRESS: { // (RawPtr)
cost++;
break;
}
case T_NARROWOOP: // Fall through
case T_OBJECT: { // Base oops are OK, but not derived oops
const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
// Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
// CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
// CMOVE'ing a derived pointer requires we also CMOVE the base. If we
// have a Phi for the base here that we convert to a CMOVE all is well
// and good. But if the base is dead, we'll not make a CMOVE. Later
// the allocator will have to produce a base by creating a CMOVE of the
// relevant bases. This puts the allocator in the business of
// manufacturing expensive instructions, generally a bad plan.
// Just Say No to Conditionally-Moved Derived Pointers.
if (tp && tp->offset() != 0)
return NULL;
cost++;
break;
}
default:
return NULL; // In particular, can't do memory or I/O
}
// Add in cost any speculative ops
for (uint j = 1; j < region->req(); j++) {
Node *proj = region->in(j);
Node *inp = phi->in(j);
if (get_ctrl(inp) == proj) { // Found local op
cost++;
// Check for a chain of dependent ops; these will all become
// speculative in a CMOV.
for (uint k = 1; k < inp->req(); k++)
if (get_ctrl(inp->in(k)) == proj)
cost += ConditionalMoveLimit; // Too much speculative goo
}
}
// See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
// This will likely Split-If, a higher-payoff operation.
for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
Node* use = phi->fast_out(k);
if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
cost += ConditionalMoveLimit;
// Is there a use inside the loop?
// Note: check only basic types since CMoveP is pinned.
if (!used_inside_loop && is_java_primitive(bt)) {
IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
if (r_loop == u_loop || r_loop->is_member(u_loop)) {
used_inside_loop = true;
}
}
}
}
Node* bol = iff->in(1);
assert(bol->Opcode() == Op_Bool, "");
int cmp_op = bol->in(1)->Opcode();
// It is expensive to generate flags from a float compare.
// Avoid duplicated float compare.
if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
float infrequent_prob = PROB_UNLIKELY_MAG(3);
// Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
if (used_inside_loop) {
if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
// BlockLayoutByFrequency optimization moves infrequent branch
// from hot path. No point in CMOV'ing in such case (110 is used
// instead of 100 to take into account not exactness of float value).
if (BlockLayoutByFrequency) {
infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
}
}
// Check for highly predictable branch. No point in CMOV'ing if
// we are going to predict accurately all the time.
if (iff->_prob < infrequent_prob ||
iff->_prob > (1.0f - infrequent_prob))
return NULL;
// --------------
// Now replace all Phis with CMOV's
Node *cmov_ctrl = iff->in(0);
uint flip = (lp->Opcode() == Op_IfTrue);
while (1) {
PhiNode* phi = NULL;
for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
Node *out = region->fast_out(i);
if (out->is_Phi()) {
phi = out->as_Phi();
break;
}
}
if (phi == NULL) break;
#ifndef PRODUCT
if (PrintOpto && VerifyLoopOptimizations) tty->print_cr("CMOV");
#endif
// Move speculative ops
for (uint j = 1; j < region->req(); j++) {
Node *proj = region->in(j);
Node *inp = phi->in(j);
if (get_ctrl(inp) == proj) { // Found local op
#ifndef PRODUCT
if (PrintOpto && VerifyLoopOptimizations) {
tty->print(" speculate: ");
inp->dump();
}
#endif
set_ctrl(inp, cmov_ctrl);
}
}
Node *cmov = CMoveNode::make( C, cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi) );
register_new_node( cmov, cmov_ctrl );
_igvn.replace_node( phi, cmov );
#ifndef PRODUCT
if (TraceLoopOpts) {
tty->print("CMOV ");
r_loop->dump_head();
if (Verbose) {
bol->in(1)->dump(1);
cmov->dump(1);
}
}
if (VerifyLoopOptimizations) verify();
#endif
}
// The useless CFG diamond will fold up later; see the optimization in
// RegionNode::Ideal.
_igvn._worklist.push(region);
return iff->in(1);
}
//------------------------------split_if_with_blocks_pre-----------------------
// Do the real work in a non-recursive function. Data nodes want to be
// cloned in the pre-order so they can feed each other nicely.
Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
// Cloning these guys is unlikely to win
int n_op = n->Opcode();
if( n_op == Op_MergeMem ) return n;
if( n->is_Proj() ) return n;
// Do not clone-up CmpFXXX variations, as these are always
// followed by a CmpI
if( n->is_Cmp() ) return n;
// Attempt to use a conditional move instead of a phi/branch
if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
Node *cmov = conditional_move( n );
if( cmov ) return cmov;
}
if( n->is_CFG() || n->is_LoadStore() )
return n;
if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
n_op == Op_Opaque2 ) {
if( !C->major_progress() ) // If chance of no more loop opts...
_igvn._worklist.push(n); // maybe we'll remove them
return n;
}
if( n->is_Con() ) return n; // No cloning for Con nodes
Node *n_ctrl = get_ctrl(n);
if( !n_ctrl ) return n; // Dead node
// Attempt to remix address expressions for loop invariants
Node *m = remix_address_expressions( n );
if( m ) return m;
// Determine if the Node has inputs from some local Phi.
// Returns the block to clone thru.
Node *n_blk = has_local_phi_input( n );
if( !n_blk ) return n;
// Do not clone the trip counter through on a CountedLoop
// (messes up the canonical shape).
if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
// Check for having no control input; not pinned. Allow
// dominating control.
if( n->in(0) ) {
Node *dom = idom(n_blk);
if( dom_lca( n->in(0), dom ) != n->in(0) )
return n;
}
// Policy: when is it profitable. You must get more wins than
// policy before it is considered profitable. Policy is usually 0,
// so 1 win is considered profitable. Big merges will require big
// cloning, so get a larger policy.
int policy = n_blk->req() >> 2;
// If the loop is a candidate for range check elimination,
// delay splitting through it's phi until a later loop optimization
if (n_blk->is_CountedLoop()) {
IdealLoopTree *lp = get_loop(n_blk);
if (lp && lp->_rce_candidate) {
return n;
}
}
// Use same limit as split_if_with_blocks_post
if( C->unique() > 35000 ) return n; // Method too big
// Split 'n' through the merge point if it is profitable
Node *phi = split_thru_phi( n, n_blk, policy );
if (!phi) return n;
// Found a Phi to split thru!
// Replace 'n' with the new phi
_igvn.replace_node( n, phi );
// Moved a load around the loop, 'en-registering' something.
if (n_blk->is_Loop() && n->is_Load() &&
!phi->in(LoopNode::LoopBackControl)->is_Load())
C->set_major_progress();
return phi;
}
static bool merge_point_too_heavy(Compile* C, Node* region) {
// Bail out if the region and its phis have too many users.
int weight = 0;
for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
weight += region->fast_out(i)->outcnt();
}
int nodes_left = MaxNodeLimit - C->live_nodes();
if (weight * 8 > nodes_left) {
#ifndef PRODUCT
if (PrintOpto)
tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
#endif
return true;
} else {
return false;
}
}
static bool merge_point_safe(Node* region) {
// 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
// having a PhiNode input. This sidesteps the dangerous case where the split
// ConvI2LNode may become TOP if the input Value() does not
// overlap the ConvI2L range, leaving a node which may not dominate its
// uses.
// A better fix for this problem can be found in the BugTraq entry, but
// expediency for Mantis demands this hack.
// 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
// split_if_with_blocks from splitting a block because we could not move around
// the FastLockNode.
for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
Node* n = region->fast_out(i);
if (n->is_Phi()) {
for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
Node* m = n->fast_out(j);
if (m->is_FastLock())
return false;
#ifdef _LP64
if (m->Opcode() == Op_ConvI2L)
return false;
#endif
}
}
}
return true;
}
//------------------------------place_near_use---------------------------------
// Place some computation next to use but not inside inner loops.
// For inner loop uses move it to the preheader area.
Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
IdealLoopTree *u_loop = get_loop( useblock );
return (u_loop->_irreducible || u_loop->_child)
? useblock
: u_loop->_head->in(LoopNode::EntryControl);
}
//------------------------------split_if_with_blocks_post----------------------
// Do the real work in a non-recursive function. CFG hackery wants to be
// in the post-order, so it can dirty the I-DOM info and not use the dirtied
// info.
void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
// Cloning Cmp through Phi's involves the split-if transform.
// FastLock is not used by an If
if( n->is_Cmp() && !n->is_FastLock() ) {
if( C->unique() > 35000 ) return; // Method too big
// Do not do 'split-if' if irreducible loops are present.
if( _has_irreducible_loops )
return;
Node *n_ctrl = get_ctrl(n);
// Determine if the Node has inputs from some local Phi.
// Returns the block to clone thru.
Node *n_blk = has_local_phi_input( n );
if( n_blk != n_ctrl ) return;
if( merge_point_too_heavy(C, n_ctrl) )
return;
if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
Node *bol = n->unique_out();
assert( bol->is_Bool(), "expect a bool here" );
if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
Node *iff = bol->unique_out();
// Check some safety conditions
if( iff->is_If() ) { // Classic split-if?
if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
} else if (iff->is_CMove()) { // Trying to split-up a CMOVE
// Can't split CMove with different control edge.
if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) return;
if( get_ctrl(iff->in(2)) == n_ctrl ||
get_ctrl(iff->in(3)) == n_ctrl )
return; // Inputs not yet split-up
if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
return; // Loop-invar test gates loop-varying CMOVE
}
} else {
return; // some other kind of node, such as an Allocate
}
// Do not do 'split-if' if some paths are dead. First do dead code
// elimination and then see if its still profitable.
for( uint i = 1; i < n_ctrl->req(); i++ )
if( n_ctrl->in(i) == C->top() )
return;
// When is split-if profitable? Every 'win' on means some control flow
// goes dead, so it's almost always a win.
int policy = 0;
// If trying to do a 'Split-If' at the loop head, it is only
// profitable if the cmp folds up on BOTH paths. Otherwise we
// risk peeling a loop forever.
// CNC - Disabled for now. Requires careful handling of loop
// body selection for the cloned code. Also, make sure we check
// for any input path not being in the same loop as n_ctrl. For
// irreducible loops we cannot check for 'n_ctrl->is_Loop()'
// because the alternative loop entry points won't be converted
// into LoopNodes.
IdealLoopTree *n_loop = get_loop(n_ctrl);
for( uint j = 1; j < n_ctrl->req(); j++ )
if( get_loop(n_ctrl->in(j)) != n_loop )
return;
// Check for safety of the merge point.
if( !merge_point_safe(n_ctrl) ) {
return;
}
// Split compare 'n' through the merge point if it is profitable
Node *phi = split_thru_phi( n, n_ctrl, policy );
if( !phi ) return;
// Found a Phi to split thru!
// Replace 'n' with the new phi
_igvn.replace_node( n, phi );
// Now split the bool up thru the phi
Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
guarantee(bolphi != NULL, "null boolean phi node");
_igvn.replace_node( bol, bolphi );
assert( iff->in(1) == bolphi, "" );
if( bolphi->Value(&_igvn)->singleton() )
return;
// Conditional-move? Must split up now
if( !iff->is_If() ) {
Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
_igvn.replace_node( iff, cmovphi );
return;
}
// Now split the IF
do_split_if( iff );
return;
}
// Check for an IF ready to split; one that has its
// condition codes input coming from a Phi at the block start.
int n_op = n->Opcode();
// Check for an IF being dominated by another IF same test
if( n_op == Op_If ) {
Node *bol = n->in(1);
uint max = bol->outcnt();
// Check for same test used more than once?
if( n_op == Op_If && max > 1 && bol->is_Bool() ) {
// Search up IDOMs to see if this IF is dominated.
Node *cutoff = get_ctrl(bol);
// Now search up IDOMs till cutoff, looking for a dominating test
Node *prevdom = n;
Node *dom = idom(prevdom);
while( dom != cutoff ) {
if( dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom ) {
// Replace the dominated test with an obvious true or false.
// Place it on the IGVN worklist for later cleanup.
C->set_major_progress();
dominated_by( prevdom, n, false, true );
#ifndef PRODUCT
if( VerifyLoopOptimizations ) verify();
#endif
return;
}
prevdom = dom;
dom = idom(prevdom);
}
}
}
// See if a shared loop-varying computation has no loop-varying uses.
// Happens if something is only used for JVM state in uncommon trap exits,
// like various versions of induction variable+offset. Clone the
// computation per usage to allow it to sink out of the loop.
if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
Node *n_ctrl = get_ctrl(n);
IdealLoopTree *n_loop = get_loop(n_ctrl);
if( n_loop != _ltree_root ) {
DUIterator_Fast imax, i = n->fast_outs(imax);
for (; i < imax; i++) {
Node* u = n->fast_out(i);
if( !has_ctrl(u) ) break; // Found control user
IdealLoopTree *u_loop = get_loop(get_ctrl(u));
if( u_loop == n_loop ) break; // Found loop-varying use
if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
}
bool did_break = (i < imax); // Did we break out of the previous loop?
if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
Node *late_load_ctrl = NULL;
if (n->is_Load()) {
// If n is a load, get and save the result from get_late_ctrl(),
// to be later used in calculating the control for n's clones.
clear_dom_lca_tags();
late_load_ctrl = get_late_ctrl(n, n_ctrl);
}
// If n is a load, and the late control is the same as the current
// control, then the cloning of n is a pointless exercise, because
// GVN will ensure that we end up where we started.
if (!n->is_Load() || late_load_ctrl != n_ctrl) {
for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
Node *u = n->last_out(j); // Clone private computation per use
_igvn.rehash_node_delayed(u);
Node *x = n->clone(); // Clone computation
Node *x_ctrl = NULL;
if( u->is_Phi() ) {
// Replace all uses of normal nodes. Replace Phi uses
// individually, so the separate Nodes can sink down
// different paths.
uint k = 1;
while( u->in(k) != n ) k++;
u->set_req( k, x );
// x goes next to Phi input path
x_ctrl = u->in(0)->in(k);
--j;
} else { // Normal use
// Replace all uses
for( uint k = 0; k < u->req(); k++ ) {
if( u->in(k) == n ) {
u->set_req( k, x );
--j;
}
}
x_ctrl = get_ctrl(u);
}
// Find control for 'x' next to use but not inside inner loops.
// For inner loop uses get the preheader area.
x_ctrl = place_near_use(x_ctrl);
if (n->is_Load()) {
// For loads, add a control edge to a CFG node outside of the loop
// to force them to not combine and return back inside the loop
// during GVN optimization (4641526).
//
// Because we are setting the actual control input, factor in
// the result from get_late_ctrl() so we respect any
// anti-dependences. (6233005).
x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
// Don't allow the control input to be a CFG splitting node.
// Such nodes should only have ProjNodes as outs, e.g. IfNode
// should only have IfTrueNode and IfFalseNode (4985384).
x_ctrl = find_non_split_ctrl(x_ctrl);
assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
x->set_req(0, x_ctrl);
}
register_new_node(x, x_ctrl);
// Some institutional knowledge is needed here: 'x' is
// yanked because if the optimizer runs GVN on it all the
// cloned x's will common up and undo this optimization and
// be forced back in the loop. This is annoying because it
// makes +VerifyOpto report false-positives on progress. I
// tried setting control edges on the x's to force them to
// not combine, but the matching gets worried when it tries
// to fold a StoreP and an AddP together (as part of an
// address expression) and the AddP and StoreP have
// different controls.
if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
}
_igvn.remove_dead_node(n);
}
}
}
}
// Check for Opaque2's who's loop has disappeared - who's input is in the
// same loop nest as their output. Remove 'em, they are no longer useful.
if( n_op == Op_Opaque2 &&
n->in(1) != NULL &&
get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
_igvn.replace_node( n, n->in(1) );
}
}
//------------------------------split_if_with_blocks---------------------------
// Check for aggressive application of 'split-if' optimization,
// using basic block level info.
void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
Node *n = C->root();
visited.set(n->_idx); // first, mark node as visited
// Do pre-visit work for root
n = split_if_with_blocks_pre( n );
uint cnt = n->outcnt();
uint i = 0;
while (true) {
// Visit all children
if (i < cnt) {
Node* use = n->raw_out(i);
++i;
if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
// Now do pre-visit work for this use
use = split_if_with_blocks_pre( use );
nstack.push(n, i); // Save parent and next use's index.
n = use; // Process all children of current use.
cnt = use->outcnt();
i = 0;
}
}
else {
// All of n's children have been processed, complete post-processing.
if (cnt != 0 && !n->is_Con()) {
assert(has_node(n), "no dead nodes");
split_if_with_blocks_post( n );
}
if (nstack.is_empty()) {
// Finished all nodes on stack.
break;
}
// Get saved parent node and next use's index. Visit the rest of uses.
n = nstack.node();
cnt = n->outcnt();
i = nstack.index();
nstack.pop();
}
}
}
//=============================================================================
//
// C L O N E A L O O P B O D Y
//
//------------------------------clone_iff--------------------------------------
// Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
// "Nearly" because all Nodes have been cloned from the original in the loop,
// but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
// through the Phi recursively, and return a Bool.
BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
// Convert this Phi into a Phi merging Bools
uint i;
for( i = 1; i < phi->req(); i++ ) {
Node *b = phi->in(i);
if( b->is_Phi() ) {
_igvn.replace_input_of(phi, i, clone_iff( b->as_Phi(), loop ));
} else {
assert( b->is_Bool(), "" );
}
}
Node *sample_bool = phi->in(1);
Node *sample_cmp = sample_bool->in(1);
// Make Phis to merge the Cmp's inputs.
PhiNode *phi1 = new (C) PhiNode( phi->in(0), Type::TOP );
PhiNode *phi2 = new (C) PhiNode( phi->in(0), Type::TOP );
for( i = 1; i < phi->req(); i++ ) {
Node *n1 = phi->in(i)->in(1)->in(1);
Node *n2 = phi->in(i)->in(1)->in(2);
phi1->set_req( i, n1 );
phi2->set_req( i, n2 );
phi1->set_type( phi1->type()->meet(n1->bottom_type()) );
phi2->set_type( phi2->type()->meet(n2->bottom_type()) );
}
// See if these Phis have been made before.
// Register with optimizer
Node *hit1 = _igvn.hash_find_insert(phi1);
if( hit1 ) { // Hit, toss just made Phi
_igvn.remove_dead_node(phi1); // Remove new phi
assert( hit1->is_Phi(), "" );
phi1 = (PhiNode*)hit1; // Use existing phi
} else { // Miss
_igvn.register_new_node_with_optimizer(phi1);
}
Node *hit2 = _igvn.hash_find_insert(phi2);
if( hit2 ) { // Hit, toss just made Phi
_igvn.remove_dead_node(phi2); // Remove new phi
assert( hit2->is_Phi(), "" );
phi2 = (PhiNode*)hit2; // Use existing phi
} else { // Miss
_igvn.register_new_node_with_optimizer(phi2);
}
// Register Phis with loop/block info
set_ctrl(phi1, phi->in(0));
set_ctrl(phi2, phi->in(0));
// Make a new Cmp
Node *cmp = sample_cmp->clone();
cmp->set_req( 1, phi1 );
cmp->set_req( 2, phi2 );
_igvn.register_new_node_with_optimizer(cmp);
set_ctrl(cmp, phi->in(0));
// Make a new Bool
Node *b = sample_bool->clone();
b->set_req(1,cmp);
_igvn.register_new_node_with_optimizer(b);
set_ctrl(b, phi->in(0));
assert( b->is_Bool(), "" );
return (BoolNode*)b;
}
//------------------------------clone_bool-------------------------------------
// Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
// "Nearly" because all Nodes have been cloned from the original in the loop,
// but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
// through the Phi recursively, and return a Bool.
CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
uint i;
// Convert this Phi into a Phi merging Bools
for( i = 1; i < phi->req(); i++ ) {
Node *b = phi->in(i);
if( b->is_Phi() ) {
_igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
} else {
assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
}
}
Node *sample_cmp = phi->in(1);
// Make Phis to merge the Cmp's inputs.
PhiNode *phi1 = new (C) PhiNode( phi->in(0), Type::TOP );
PhiNode *phi2 = new (C) PhiNode( phi->in(0), Type::TOP );
for( uint j = 1; j < phi->req(); j++ ) {
Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
Node *n1, *n2;
if( cmp_top->is_Cmp() ) {
n1 = cmp_top->in(1);
n2 = cmp_top->in(2);
} else {
n1 = n2 = cmp_top;
}
phi1->set_req( j, n1 );
phi2->set_req( j, n2 );
phi1->set_type( phi1->type()->meet(n1->bottom_type()) );
phi2->set_type( phi2->type()->meet(n2->bottom_type()) );
}
// See if these Phis have been made before.
// Register with optimizer
Node *hit1 = _igvn.hash_find_insert(phi1);
if( hit1 ) { // Hit, toss just made Phi
_igvn.remove_dead_node(phi1); // Remove new phi
assert( hit1->is_Phi(), "" );
phi1 = (PhiNode*)hit1; // Use existing phi
} else { // Miss
_igvn.register_new_node_with_optimizer(phi1);
}
Node *hit2 = _igvn.hash_find_insert(phi2);
if( hit2 ) { // Hit, toss just made Phi
_igvn.remove_dead_node(phi2); // Remove new phi
assert( hit2->is_Phi(), "" );
phi2 = (PhiNode*)hit2; // Use existing phi
} else { // Miss
_igvn.register_new_node_with_optimizer(phi2);
}
// Register Phis with loop/block info
set_ctrl(phi1, phi->in(0));
set_ctrl(phi2, phi->in(0));
// Make a new Cmp
Node *cmp = sample_cmp->clone();
cmp->set_req( 1, phi1 );
cmp->set_req( 2, phi2 );
_igvn.register_new_node_with_optimizer(cmp);
set_ctrl(cmp, phi->in(0));
assert( cmp->is_Cmp(), "" );
return (CmpNode*)cmp;
}
//------------------------------sink_use---------------------------------------
// If 'use' was in the loop-exit block, it now needs to be sunk
// below the post-loop merge point.
void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
set_ctrl(use, post_loop);
for (DUIterator j = use->outs(); use->has_out(j); j++)
sink_use(use->out(j), post_loop);
}
}
//------------------------------clone_loop-------------------------------------
//
// C L O N E A L O O P B O D Y
//
// This is the basic building block of the loop optimizations. It clones an
// entire loop body. It makes an old_new loop body mapping; with this mapping
// you can find the new-loop equivalent to an old-loop node. All new-loop
// nodes are exactly equal to their old-loop counterparts, all edges are the
// same. All exits from the old-loop now have a RegionNode that merges the
// equivalent new-loop path. This is true even for the normal "loop-exit"
// condition. All uses of loop-invariant old-loop values now come from (one
// or more) Phis that merge their new-loop equivalents.
//
// This operation leaves the graph in an illegal state: there are two valid
// control edges coming from the loop pre-header to both loop bodies. I'll
// definitely have to hack the graph after running this transform.
//
// From this building block I will further edit edges to perform loop peeling
// or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
//
// Parameter side_by_size_idom:
// When side_by_size_idom is NULL, the dominator tree is constructed for
// the clone loop to dominate the original. Used in construction of
// pre-main-post loop sequence.
// When nonnull, the clone and original are side-by-side, both are
// dominated by the side_by_side_idom node. Used in construction of
// unswitched loops.
void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
Node* side_by_side_idom) {
// Step 1: Clone the loop body. Make the old->new mapping.
uint i;
for( i = 0; i < loop->_body.size(); i++ ) {
Node *old = loop->_body.at(i);
Node *nnn = old->clone();
old_new.map( old->_idx, nnn );
_igvn.register_new_node_with_optimizer(nnn);
}
// Step 2: Fix the edges in the new body. If the old input is outside the
// loop use it. If the old input is INside the loop, use the corresponding
// new node instead.
for( i = 0; i < loop->_body.size(); i++ ) {
Node *old = loop->_body.at(i);
Node *nnn = old_new[old->_idx];
// Fix CFG/Loop controlling the new node
if (has_ctrl(old)) {
set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
} else {
set_loop(nnn, loop->_parent);
if (old->outcnt() > 0) {
set_idom( nnn, old_new[idom(old)->_idx], dd );
}
}
// Correct edges to the new node
for( uint j = 0; j < nnn->req(); j++ ) {
Node *n = nnn->in(j);
if( n ) {
IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
if( loop->is_member( old_in_loop ) )
nnn->set_req(j, old_new[n->_idx]);
}
}
_igvn.hash_find_insert(nnn);
}
Node *newhead = old_new[loop->_head->_idx];
set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
// Step 3: Now fix control uses. Loop varying control uses have already
// been fixed up (as part of all input edges in Step 2). Loop invariant
// control uses must be either an IfFalse or an IfTrue. Make a merge
// point to merge the old and new IfFalse/IfTrue nodes; make the use
// refer to this.
ResourceArea *area = Thread::current()->resource_area();
Node_List worklist(area);
uint new_counter = C->unique();
for( i = 0; i < loop->_body.size(); i++ ) {
Node* old = loop->_body.at(i);
if( !old->is_CFG() ) continue;
Node* nnn = old_new[old->_idx];
// Copy uses to a worklist, so I can munge the def-use info
// with impunity.
for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
worklist.push(old->fast_out(j));
while( worklist.size() ) { // Visit all uses
Node *use = worklist.pop();
if (!has_node(use)) continue; // Ignore dead nodes
IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
if( !loop->is_member( use_loop ) && use->is_CFG() ) {
// Both OLD and USE are CFG nodes here.
assert( use->is_Proj(), "" );
// Clone the loop exit control projection
Node *newuse = use->clone();
newuse->set_req(0,nnn);
_igvn.register_new_node_with_optimizer(newuse);
set_loop(newuse, use_loop);
set_idom(newuse, nnn, dom_depth(nnn) + 1 );
// We need a Region to merge the exit from the peeled body and the
// exit from the old loop body.
RegionNode *r = new (C) RegionNode(3);
// Map the old use to the new merge point
old_new.map( use->_idx, r );
uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
// The original user of 'use' uses 'r' instead.
for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
Node* useuse = use->last_out(l);
_igvn.rehash_node_delayed(useuse);
uint uses_found = 0;
if( useuse->in(0) == use ) {
useuse->set_req(0, r);
uses_found++;
if( useuse->is_CFG() ) {
assert( dom_depth(useuse) > dd_r, "" );
set_idom(useuse, r, dom_depth(useuse));
}
}
for( uint k = 1; k < useuse->req(); k++ ) {
if( useuse->in(k) == use ) {
useuse->set_req(k, r);
uses_found++;
}
}
l -= uses_found; // we deleted 1 or more copies of this edge
}
// Now finish up 'r'
r->set_req( 1, newuse );
r->set_req( 2, use );
_igvn.register_new_node_with_optimizer(r);
set_loop(r, use_loop);
set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
} // End of if a loop-exit test
}
}
// Step 4: If loop-invariant use is not control, it must be dominated by a
// loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
// there if needed. Make a Phi there merging old and new used values.
Node_List *split_if_set = NULL;
Node_List *split_bool_set = NULL;
Node_List *split_cex_set = NULL;
for( i = 0; i < loop->_body.size(); i++ ) {
Node* old = loop->_body.at(i);
Node* nnn = old_new[old->_idx];
// Copy uses to a worklist, so I can munge the def-use info
// with impunity.
for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
worklist.push(old->fast_out(j));
while( worklist.size() ) {
Node *use = worklist.pop();
if (!has_node(use)) continue; // Ignore dead nodes
if (use->in(0) == C->top()) continue;
IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
// Check for data-use outside of loop - at least one of OLD or USE
// must not be a CFG node.
if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
// If the Data use is an IF, that means we have an IF outside of the
// loop that is switching on a condition that is set inside of the
// loop. Happens if people set a loop-exit flag; then test the flag
// in the loop to break the loop, then test is again outside of the
// loop to determine which way the loop exited.
if( use->is_If() || use->is_CMove() ) {
// Since this code is highly unlikely, we lazily build the worklist
// of such Nodes to go split.
if( !split_if_set )
split_if_set = new Node_List(area);
split_if_set->push(use);
}
if( use->is_Bool() ) {
if( !split_bool_set )
split_bool_set = new Node_List(area);
split_bool_set->push(use);
}
if( use->Opcode() == Op_CreateEx ) {
if( !split_cex_set )
split_cex_set = new Node_List(area);
split_cex_set->push(use);
}
// Get "block" use is in
uint idx = 0;
while( use->in(idx) != old ) idx++;
Node *prev = use->is_CFG() ? use : get_ctrl(use);
assert( !loop->is_member( get_loop( prev ) ), "" );
Node *cfg = prev->_idx >= new_counter
? prev->in(2)
: idom(prev);
if( use->is_Phi() ) // Phi use is in prior block
cfg = prev->in(idx); // NOT in block of Phi itself
if (cfg->is_top()) { // Use is dead?
_igvn.replace_input_of(use, idx, C->top());
continue;
}
while( !loop->is_member( get_loop( cfg ) ) ) {
prev = cfg;
cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
}
// If the use occurs after merging several exits from the loop, then
// old value must have dominated all those exits. Since the same old
// value was used on all those exits we did not need a Phi at this
// merge point. NOW we do need a Phi here. Each loop exit value
// is now merged with the peeled body exit; each exit gets its own
// private Phi and those Phis need to be merged here.
Node *phi;
if( prev->is_Region() ) {
if( idx == 0 ) { // Updating control edge?
phi = prev; // Just use existing control
} else { // Else need a new Phi
phi = PhiNode::make( prev, old );
// Now recursively fix up the new uses of old!
for( uint i = 1; i < prev->req(); i++ ) {
worklist.push(phi); // Onto worklist once for each 'old' input
}
}
} else {
// Get new RegionNode merging old and new loop exits
prev = old_new[prev->_idx];
assert( prev, "just made this in step 7" );
if( idx == 0 ) { // Updating control edge?
phi = prev; // Just use existing control
} else { // Else need a new Phi
// Make a new Phi merging data values properly
phi = PhiNode::make( prev, old );
phi->set_req( 1, nnn );
}
}
// If inserting a new Phi, check for prior hits
if( idx != 0 ) {
Node *hit = _igvn.hash_find_insert(phi);
if( hit == NULL ) {
_igvn.register_new_node_with_optimizer(phi); // Register new phi
} else { // or
// Remove the new phi from the graph and use the hit
_igvn.remove_dead_node(phi);
phi = hit; // Use existing phi
}
set_ctrl(phi, prev);
}
// Make 'use' use the Phi instead of the old loop body exit value
_igvn.replace_input_of(use, idx, phi);
if( use->_idx >= new_counter ) { // If updating new phis
// Not needed for correctness, but prevents a weak assert
// in AddPNode from tripping (when we end up with different
// base & derived Phis that will become the same after
// IGVN does CSE).
Node *hit = _igvn.hash_find_insert(use);
if( hit ) // Go ahead and re-hash for hits.
_igvn.replace_node( use, hit );
}
// If 'use' was in the loop-exit block, it now needs to be sunk
// below the post-loop merge point.
sink_use( use, prev );
}
}
}
// Check for IFs that need splitting/cloning. Happens if an IF outside of
// the loop uses a condition set in the loop. The original IF probably
// takes control from one or more OLD Regions (which in turn get from NEW
// Regions). In any case, there will be a set of Phis for each merge point
// from the IF up to where the original BOOL def exists the loop.
if( split_if_set ) {
while( split_if_set->size() ) {
Node *iff = split_if_set->pop();
if( iff->in(1)->is_Phi() ) {
BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
_igvn.replace_input_of(iff, 1, b);
}
}
}
if( split_bool_set ) {
while( split_bool_set->size() ) {
Node *b = split_bool_set->pop();
Node *phi = b->in(1);
assert( phi->is_Phi(), "" );
CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
_igvn.replace_input_of(b, 1, cmp);
}
}
if( split_cex_set ) {
while( split_cex_set->size() ) {
Node *b = split_cex_set->pop();
assert( b->in(0)->is_Region(), "" );
assert( b->in(1)->is_Phi(), "" );
assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
split_up( b, b->in(0), NULL );
}
}
}
//---------------------- stride_of_possible_iv -------------------------------------
// Looks for an iff/bool/comp with one operand of the compare
// being a cycle involving an add and a phi,
// with an optional truncation (left-shift followed by a right-shift)
// of the add. Returns zero if not an iv.
int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
Node* trunc1 = NULL;
Node* trunc2 = NULL;
const TypeInt* ttype = NULL;
if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
return 0;
}
BoolNode* bl = iff->in(1)->as_Bool();
Node* cmp = bl->in(1);
if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
return 0;
}
// Must have an invariant operand
if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
return 0;
}
Node* add2 = NULL;
Node* cmp1 = cmp->in(1);
if (cmp1->is_Phi()) {
// (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
Node* phi = cmp1;
for (uint i = 1; i < phi->req(); i++) {
Node* in = phi->in(i);
Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
&trunc1, &trunc2, &ttype);
if (add && add->in(1) == phi) {
add2 = add->in(2);
break;
}
}
} else {
// (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
Node* addtrunc = cmp1;
Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
&trunc1, &trunc2, &ttype);
if (add && add->in(1)->is_Phi()) {
Node* phi = add->in(1);
for (uint i = 1; i < phi->req(); i++) {
if (phi->in(i) == addtrunc) {
add2 = add->in(2);
break;
}
}
}
}
if (add2 != NULL) {
const TypeInt* add2t = _igvn.type(add2)->is_int();
if (add2t->is_con()) {
return add2t->get_con();
}
}
return 0;
}
//---------------------- stay_in_loop -------------------------------------
// Return the (unique) control output node that's in the loop (if it exists.)
Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
Node* unique = NULL;
if (!n) return NULL;
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
Node* use = n->fast_out(i);
if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
if (unique != NULL) {
return NULL;
}
unique = use;
}
}
return unique;
}
//------------------------------ register_node -------------------------------------
// Utility to register node "n" with PhaseIdealLoop
void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
_igvn.register_new_node_with_optimizer(n);
loop->_body.push(n);
if (n->is_CFG()) {
set_loop(n, loop);
set_idom(n, pred, ddepth);
} else {
set_ctrl(n, pred);
}
}
//------------------------------ proj_clone -------------------------------------
// Utility to create an if-projection
ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
ProjNode* c = p->clone()->as_Proj();
c->set_req(0, iff);
return c;
}
//------------------------------ short_circuit_if -------------------------------------
// Force the iff control output to be the live_proj
Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
guarantee(live_proj != NULL, "null projection");
int proj_con = live_proj->_con;
assert(proj_con == 0 || proj_con == 1, "false or true projection");
Node *con = _igvn.intcon(proj_con);
set_ctrl(con, C->root());
if (iff) {
iff->set_req(1, con);
}
return con;
}
//------------------------------ insert_if_before_proj -------------------------------------
// Insert a new if before an if projection (* - new node)
//
// before
// if(test)
// / \
// v v
// other-proj proj (arg)
//
// after
// if(test)
// / \
// / v
// | * proj-clone
// v |
// other-proj v
// * new_if(relop(cmp[IU](left,right)))
// / \
// v v
// * new-proj proj
// (returned)
//
ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
IfNode* iff = proj->in(0)->as_If();
IdealLoopTree *loop = get_loop(proj);
ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
int ddepth = dom_depth(proj);
_igvn.rehash_node_delayed(iff);
_igvn.rehash_node_delayed(proj);
proj->set_req(0, NULL); // temporary disconnect
ProjNode* proj2 = proj_clone(proj, iff);
register_node(proj2, loop, iff, ddepth);
Node* cmp = Signed ? (Node*) new (C)CmpINode(left, right) : (Node*) new (C)CmpUNode(left, right);
register_node(cmp, loop, proj2, ddepth);
BoolNode* bol = new (C)BoolNode(cmp, relop);
register_node(bol, loop, proj2, ddepth);
IfNode* new_if = new (C)IfNode(proj2, bol, iff->_prob, iff->_fcnt);
register_node(new_if, loop, proj2, ddepth);
proj->set_req(0, new_if); // reattach
set_idom(proj, new_if, ddepth);
ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
guarantee(new_exit != NULL, "null exit node");
register_node(new_exit, get_loop(other_proj), new_if, ddepth);
return new_exit;
}
//------------------------------ insert_region_before_proj -------------------------------------
// Insert a region before an if projection (* - new node)
//
// before
// if(test)
// / |
// v |
// proj v
// other-proj
//
// after
// if(test)
// / |
// v |
// * proj-clone v
// | other-proj
// v
// * new-region
// |
// v
// * dum_if
// / \
// v \
// * dum-proj v
// proj
//
RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
IfNode* iff = proj->in(0)->as_If();
IdealLoopTree *loop = get_loop(proj);
ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
int ddepth = dom_depth(proj);
_igvn.rehash_node_delayed(iff);
_igvn.rehash_node_delayed(proj);
proj->set_req(0, NULL); // temporary disconnect
ProjNode* proj2 = proj_clone(proj, iff);
register_node(proj2, loop, iff, ddepth);
RegionNode* reg = new (C)RegionNode(2);
reg->set_req(1, proj2);
register_node(reg, loop, iff, ddepth);
IfNode* dum_if = new (C)IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
register_node(dum_if, loop, reg, ddepth);
proj->set_req(0, dum_if); // reattach
set_idom(proj, dum_if, ddepth);
ProjNode* dum_proj = proj_clone(other_proj, dum_if);
register_node(dum_proj, loop, dum_if, ddepth);
return reg;
}
//------------------------------ insert_cmpi_loop_exit -------------------------------------
// Clone a signed compare loop exit from an unsigned compare and
// insert it before the unsigned cmp on the stay-in-loop path.
// All new nodes inserted in the dominator tree between the original
// if and it's projections. The original if test is replaced with
// a constant to force the stay-in-loop path.
//
// This is done to make sure that the original if and it's projections
// still dominate the same set of control nodes, that the ctrl() relation
// from data nodes to them is preserved, and that their loop nesting is
// preserved.
//
// before
// if(i <u limit) unsigned compare loop exit
// / |
// v v
// exit-proj stay-in-loop-proj
//
// after
// if(stay-in-loop-const) original if
// / |
// / v
// / if(i < limit) new signed test
// / / |
// / / v
// / / if(i <u limit) new cloned unsigned test
// / / / |
// v v v |
// region |
// | |
// dum-if |
// / | |
// ether | |
// v v
// exit-proj stay-in-loop-proj
//
IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
const bool Signed = true;
const bool Unsigned = false;
BoolNode* bol = if_cmpu->in(1)->as_Bool();
if (bol->_test._test != BoolTest::lt) return NULL;
CmpNode* cmpu = bol->in(1)->as_Cmp();
if (cmpu->Opcode() != Op_CmpU) return NULL;
int stride = stride_of_possible_iv(if_cmpu);
if (stride == 0) return NULL;
Node* lp_proj = stay_in_loop(if_cmpu, loop);
guarantee(lp_proj != NULL, "null loop node");
ProjNode* lp_continue = lp_proj->as_Proj();
ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
Node* limit = NULL;
if (stride > 0) {
limit = cmpu->in(2);
} else {
limit = _igvn.makecon(TypeInt::ZERO);
set_ctrl(limit, C->root());
}
// Create a new region on the exit path
RegionNode* reg = insert_region_before_proj(lp_exit);
guarantee(reg != NULL, "null region node");
// Clone the if-cmpu-true-false using a signed compare
BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
reg->add_req(cmpi_exit);
// Clone the if-cmpu-true-false
BoolTest::mask rel_u = bol->_test._test;
ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
reg->add_req(cmpu_exit);
// Force original if to stay in loop.
short_circuit_if(if_cmpu, lp_continue);
return cmpi_exit->in(0)->as_If();
}
//------------------------------ remove_cmpi_loop_exit -------------------------------------
// Remove a previously inserted signed compare loop exit.
void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
Node* lp_proj = stay_in_loop(if_cmp, loop);
assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
stay_in_loop(lp_proj, loop)->is_If() &&
stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
set_ctrl(con, C->root());
if_cmp->set_req(1, con);
}
//------------------------------ scheduled_nodelist -------------------------------------
// Create a post order schedule of nodes that are in the
// "member" set. The list is returned in "sched".
// The first node in "sched" is the loop head, followed by
// nodes which have no inputs in the "member" set, and then
// followed by the nodes that have an immediate input dependence
// on a node in "sched".
void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
assert(member.test(loop->_head->_idx), "loop head must be in member set");
Arena *a = Thread::current()->resource_area();
VectorSet visited(a);
Node_Stack nstack(a, loop->_body.size());
Node* n = loop->_head; // top of stack is cached in "n"
uint idx = 0;
visited.set(n->_idx);
// Initially push all with no inputs from within member set
for(uint i = 0; i < loop->_body.size(); i++ ) {
Node *elt = loop->_body.at(i);
if (member.test(elt->_idx)) {
bool found = false;
for (uint j = 0; j < elt->req(); j++) {
Node* def = elt->in(j);
if (def && member.test(def->_idx) && def != elt) {
found = true;
break;
}
}
if (!found && elt != loop->_head) {
nstack.push(n, idx);
n = elt;
assert(!visited.test(n->_idx), "not seen yet");
visited.set(n->_idx);
}
}
}
// traverse out's that are in the member set
while (true) {
if (idx < n->outcnt()) {
Node* use = n->raw_out(idx);
idx++;
if (!visited.test_set(use->_idx)) {
if (member.test(use->_idx)) {
nstack.push(n, idx);
n = use;
idx = 0;
}
}
} else {
// All outputs processed
sched.push(n);
if (nstack.is_empty()) break;
n = nstack.node();
idx = nstack.index();
nstack.pop();
}
}
}
//------------------------------ has_use_in_set -------------------------------------
// Has a use in the vector set
bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
Node* use = n->fast_out(j);
if (vset.test(use->_idx)) {
return true;
}
}
return false;
}
//------------------------------ has_use_internal_to_set -------------------------------------
// Has use internal to the vector set (ie. not in a phi at the loop head)
bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
Node* head = loop->_head;
for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
Node* use = n->fast_out(j);
if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
return true;
}
}
return false;
}
//------------------------------ clone_for_use_outside_loop -------------------------------------
// clone "n" for uses that are outside of loop
int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
int cloned = 0;
assert(worklist.size() == 0, "should be empty");
for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
Node* use = n->fast_out(j);
if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
worklist.push(use);
}
}
while( worklist.size() ) {
Node *use = worklist.pop();
if (!has_node(use) || use->in(0) == C->top()) continue;
uint j;
for (j = 0; j < use->req(); j++) {
if (use->in(j) == n) break;
}
assert(j < use->req(), "must be there");
// clone "n" and insert it between the inputs of "n" and the use outside the loop
Node* n_clone = n->clone();
_igvn.replace_input_of(use, j, n_clone);
cloned++;
Node* use_c;
if (!use->is_Phi()) {
use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
} else {
// Use in a phi is considered a use in the associated predecessor block
use_c = use->in(0)->in(j);
}
set_ctrl(n_clone, use_c);
assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
get_loop(use_c)->_body.push(n_clone);
_igvn.register_new_node_with_optimizer(n_clone);
#if !defined(PRODUCT)
if (TracePartialPeeling) {
tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
}
#endif
}
return cloned;
}
//------------------------------ clone_for_special_use_inside_loop -------------------------------------
// clone "n" for special uses that are in the not_peeled region.
// If these def-uses occur in separate blocks, the code generator
// marks the method as not compilable. For example, if a "BoolNode"
// is in a different basic block than the "IfNode" that uses it, then
// the compilation is aborted in the code generator.
void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
if (n->is_Phi() || n->is_Load()) {
return;
}
assert(worklist.size() == 0, "should be empty");
for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
Node* use = n->fast_out(j);
if ( not_peel.test(use->_idx) &&
(use->is_If() || use->is_CMove() || use->is_Bool()) &&
use->in(1) == n) {
worklist.push(use);
}
}
if (worklist.size() > 0) {
// clone "n" and insert it between inputs of "n" and the use
Node* n_clone = n->clone();
loop->_body.push(n_clone);
_igvn.register_new_node_with_optimizer(n_clone);
set_ctrl(n_clone, get_ctrl(n));
sink_list.push(n_clone);
not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
#if !defined(PRODUCT)
if (TracePartialPeeling) {
tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
}
#endif
while( worklist.size() ) {
Node *use = worklist.pop();
_igvn.rehash_node_delayed(use);
for (uint j = 1; j < use->req(); j++) {
if (use->in(j) == n) {
use->set_req(j, n_clone);
}
}
}
}
}
//------------------------------ insert_phi_for_loop -------------------------------------
// Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
Node *phi = PhiNode::make(lp, back_edge_val);
phi->set_req(LoopNode::EntryControl, lp_entry_val);
// Use existing phi if it already exists
Node *hit = _igvn.hash_find_insert(phi);
if( hit == NULL ) {
_igvn.register_new_node_with_optimizer(phi);
set_ctrl(phi, lp);
} else {
// Remove the new phi from the graph and use the hit
_igvn.remove_dead_node(phi);
phi = hit;
}
_igvn.replace_input_of(use, idx, phi);
}
#ifdef ASSERT
//------------------------------ is_valid_loop_partition -------------------------------------
// Validate the loop partition sets: peel and not_peel
bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
VectorSet& not_peel ) {
uint i;
// Check that peel_list entries are in the peel set
for (i = 0; i < peel_list.size(); i++) {
if (!peel.test(peel_list.at(i)->_idx)) {
return false;
}
}
// Check at loop members are in one of peel set or not_peel set
for (i = 0; i < loop->_body.size(); i++ ) {
Node *def = loop->_body.at(i);
uint di = def->_idx;
// Check that peel set elements are in peel_list
if (peel.test(di)) {
if (not_peel.test(di)) {
return false;
}
// Must be in peel_list also
bool found = false;
for (uint j = 0; j < peel_list.size(); j++) {
if (peel_list.at(j)->_idx == di) {
found = true;
break;
}
}
if (!found) {
return false;
}
} else if (not_peel.test(di)) {
if (peel.test(di)) {
return false;
}
} else {
return false;
}
}
return true;
}
//------------------------------ is_valid_clone_loop_exit_use -------------------------------------
// Ensure a use outside of loop is of the right form
bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
return (use->is_Phi() &&
use_c->is_Region() && use_c->req() == 3 &&
(use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
}
//------------------------------ is_valid_clone_loop_form -------------------------------------
// Ensure that all uses outside of loop are of the right form
bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
uint orig_exit_idx, uint clone_exit_idx) {
uint len = peel_list.size();
for (uint i = 0; i < len; i++) {
Node *def = peel_list.at(i);
for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
Node *use = def->fast_out(j);
Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
if (!loop->is_member(get_loop(use_c))) {
// use is not in the loop, check for correct structure
if (use->in(0) == def) {
// Okay
} else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
return false;
}
}
}
}
return true;
}
#endif
//------------------------------ partial_peel -------------------------------------
// Partially peel (aka loop rotation) the top portion of a loop (called
// the peel section below) by cloning it and placing one copy just before
// the new loop head and the other copy at the bottom of the new loop.
//
// before after where it came from
//
// stmt1 stmt1
// loop: stmt2 clone
// stmt2 if condA goto exitA clone
// if condA goto exitA new_loop: new
// stmt3 stmt3 clone
// if !condB goto loop if condB goto exitB clone
// exitB: stmt2 orig
// stmt4 if !condA goto new_loop orig
// exitA: goto exitA
// exitB:
// stmt4
// exitA:
//
// Step 1: find the cut point: an exit test on probable
// induction variable.
// Step 2: schedule (with cloning) operations in the peel
// section that can be executed after the cut into
// the section that is not peeled. This may need
// to clone operations into exit blocks. For
// instance, a reference to A[i] in the not-peel
// section and a reference to B[i] in an exit block
// may cause a left-shift of i by 2 to be placed
// in the peel block. This step will clone the left
// shift into the exit block and sink the left shift
// from the peel to the not-peel section.
// Step 3: clone the loop, retarget the control, and insert
// phis for values that are live across the new loop
// head. This is very dependent on the graph structure
// from clone_loop. It creates region nodes for
// exit control and associated phi nodes for values
// flow out of the loop through that exit. The region
// node is dominated by the clone's control projection.
// So the clone's peel section is placed before the
// new loop head, and the clone's not-peel section is
// forms the top part of the new loop. The original
// peel section forms the tail of the new loop.
// Step 4: update the dominator tree and recompute the
// dominator depth.
//
// orig
//
// stmt1
// |
// v
// loop predicate
// |
// v
// loop<----+
// | |
// stmt2 |
// | |
// v |
// ifA |
// / | |
// v v |
// false true ^ <-- last_peel
// / | |
// / ===|==cut |
// / stmt3 | <-- first_not_peel
// / | |
// | v |
// v ifB |
// exitA: / \ |
// / \ |
// v v |
// false true |
// / \ |
// / ----+
// |
// v
// exitB:
// stmt4
//
//
// after clone loop
//
// stmt1
// |
// v
// loop predicate
// / \
// clone / \ orig
// / \
// / \
// v v
// +---->loop loop<----+
// | | | |
// | stmt2 stmt2 |
// | | | |
// | v v |
// | ifA ifA |
// | | \ / | |
// | v v v v |
// ^ true false false true ^ <-- last_peel
// | | ^ \ / | |
// | cut==|== \ \ / ===|==cut |
// | stmt3 \ \ / stmt3 | <-- first_not_peel
// | | dom | | | |
// | v \ 1v v2 v |
// | ifB regionA ifB |
// | / \ | / \ |
// | / \ v / \ |
// | v v exitA: v v |
// | true false false true |
// | / ^ \ / \ |
// +---- \ \ / ----+
// dom \ /
// \ 1v v2
// regionB
// |
// v
// exitB:
// stmt4
//
//
// after partial peel
//
// stmt1
// |
// v
// loop predicate
// /
// clone / orig
// / TOP
// / \
// v v
// TOP->loop loop----+
// | | |
// stmt2 stmt2 |
// | | |
// v v |
// ifA ifA |
// | \ / | |
// v v v v |
// true false false true | <-- last_peel
// | ^ \ / +------|---+
// +->newloop \ \ / === ==cut | |
// | stmt3 \ \ / TOP | |
// | | dom | | stmt3 | | <-- first_not_peel
// | v \ 1v v2 v | |
// | ifB regionA ifB ^ v
// | / \ | / \ | |
// | / \ v / \ | |
// | v v exitA: v v | |
// | true false false true | |
// | / ^ \ / \ | |
// | | \ \ / v | |
// | | dom \ / TOP | |
// | | \ 1v v2 | |
// ^ v regionB | |
// | | | | |
// | | v ^ v
// | | exitB: | |
// | | stmt4 | |
// | +------------>-----------------+ |
// | |
// +-----------------<---------------------+
//
//
// final graph
//
// stmt1
// |
// v
// loop predicate
// |
// v
// stmt2 clone
// |
// v
// ........> ifA clone
// : / |
// dom / |
// : v v
// : false true
// : | |
// : | v
// : | newloop<-----+
// : | | |
// : | stmt3 clone |
// : | | |
// : | v |
// : | ifB |
// : | / \ |
// : | v v |
// : | false true |
// : | | | |
// : | v stmt2 |
// : | exitB: | |
// : | stmt4 v |
// : | ifA orig |
// : | / \ |
// : | / \ |
// : | v v |
// : | false true |
// : | / \ |
// : v v -----+
// RegionA
// |
// v
// exitA
//
bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
if (!loop->_head->is_Loop()) {
return false; }
LoopNode *head = loop->_head->as_Loop();
if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
return false;
}
// Check for complex exit control
for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
Node *n = loop->_body.at(ii);
int opc = n->Opcode();
if (n->is_Call() ||
opc == Op_Catch ||
opc == Op_CatchProj ||
opc == Op_Jump ||
opc == Op_JumpProj ||
opc == Op_FlagsProj) {
#if !defined(PRODUCT)
if (TracePartialPeeling) {
tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
}
#endif
return false;
}
}
int dd = dom_depth(head);
// Step 1: find cut point
// Walk up dominators to loop head looking for first loop exit
// which is executed on every path thru loop.
IfNode *peel_if = NULL;
IfNode *peel_if_cmpu = NULL;
Node *iff = loop->tail();
while( iff != head ) {
if( iff->is_If() ) {
Node *ctrl = get_ctrl(iff->in(1));
if (ctrl->is_top()) return false; // Dead test on live IF.
// If loop-varying exit-test, check for induction variable
if( loop->is_member(get_loop(ctrl)) &&
loop->is_loop_exit(iff) &&
is_possible_iv_test(iff)) {
Node* cmp = iff->in(1)->in(1);
if (cmp->Opcode() == Op_CmpI) {
peel_if = iff->as_If();
} else {
assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
peel_if_cmpu = iff->as_If();
}
}
}
iff = idom(iff);
}
// Prefer signed compare over unsigned compare.
IfNode* new_peel_if = NULL;
if (peel_if == NULL) {
if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
return false; // No peel point found
}
new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
if (new_peel_if == NULL) {
return false; // No peel point found
}
peel_if = new_peel_if;
}
Node* last_peel = stay_in_loop(peel_if, loop);
Node* first_not_peeled = stay_in_loop(last_peel, loop);
if (first_not_peeled == NULL || first_not_peeled == head) {
return false;
}
#if !defined(PRODUCT)
if (TraceLoopOpts) {
tty->print("PartialPeel ");
loop->dump_head();
}
if (TracePartialPeeling) {
tty->print_cr("before partial peel one iteration");
Node_List wl;
Node* t = head->in(2);
while (true) {
wl.push(t);
if (t == head) break;
t = idom(t);
}
while (wl.size() > 0) {
Node* tt = wl.pop();
tt->dump();
if (tt == last_peel) tty->print_cr("-- cut --");
}
}
#endif
ResourceArea *area = Thread::current()->resource_area();
VectorSet peel(area);
VectorSet not_peel(area);
Node_List peel_list(area);
Node_List worklist(area);
Node_List sink_list(area);
// Set of cfg nodes to peel are those that are executable from
// the head through last_peel.
assert(worklist.size() == 0, "should be empty");
worklist.push(head);
peel.set(head->_idx);
while (worklist.size() > 0) {
Node *n = worklist.pop();
if (n != last_peel) {
for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
Node* use = n->fast_out(j);
if (use->is_CFG() &&
loop->is_member(get_loop(use)) &&
!peel.test_set(use->_idx)) {
worklist.push(use);
}
}
}
}
// Set of non-cfg nodes to peel are those that are control
// dependent on the cfg nodes.
uint i;
for(i = 0; i < loop->_body.size(); i++ ) {
Node *n = loop->_body.at(i);
Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
if (peel.test(n_c->_idx)) {
peel.set(n->_idx);
} else {
not_peel.set(n->_idx);
}
}
// Step 2: move operations from the peeled section down into the
// not-peeled section
// Get a post order schedule of nodes in the peel region
// Result in right-most operand.
scheduled_nodelist(loop, peel, peel_list );
assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
// For future check for too many new phis
uint old_phi_cnt = 0;
for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
Node* use = head->fast_out(j);
if (use->is_Phi()) old_phi_cnt++;
}
#if !defined(PRODUCT)
if (TracePartialPeeling) {
tty->print_cr("\npeeled list");
}
#endif
// Evacuate nodes in peel region into the not_peeled region if possible
uint new_phi_cnt = 0;
uint cloned_for_outside_use = 0;
for (i = 0; i < peel_list.size();) {
Node* n = peel_list.at(i);
#if !defined(PRODUCT)
if (TracePartialPeeling) n->dump();
#endif
bool incr = true;
if ( !n->is_CFG() ) {
if ( has_use_in_set(n, not_peel) ) {
// If not used internal to the peeled region,
// move "n" from peeled to not_peeled region.
if ( !has_use_internal_to_set(n, peel, loop) ) {
// if not pinned and not a load (which maybe anti-dependent on a store)
// and not a CMove (Matcher expects only bool->cmove).
if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
sink_list.push(n);
peel >>= n->_idx; // delete n from peel set.
not_peel <<= n->_idx; // add n to not_peel set.
peel_list.remove(i);
incr = false;
#if !defined(PRODUCT)
if (TracePartialPeeling) {
tty->print_cr("sink to not_peeled region: %d newbb: %d",
n->_idx, get_ctrl(n)->_idx);
}
#endif
}
} else {
// Otherwise check for special def-use cases that span
// the peel/not_peel boundary such as bool->if
clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
new_phi_cnt++;
}
}
}
if (incr) i++;
}
if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
#if !defined(PRODUCT)
if (TracePartialPeeling) {
tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
}
#endif
if (new_peel_if != NULL) {
remove_cmpi_loop_exit(new_peel_if, loop);
}
// Inhibit more partial peeling on this loop
assert(!head->is_partial_peel_loop(), "not partial peeled");
head->mark_partial_peel_failed();
if (cloned_for_outside_use > 0) {
// Terminate this round of loop opts because
// the graph outside this loop was changed.
C->set_major_progress();
return true;
}
return false;
}
// Step 3: clone loop, retarget control, and insert new phis
// Create new loop head for new phis and to hang
// the nodes being moved (sinked) from the peel region.
LoopNode* new_head = new (C) LoopNode(last_peel, last_peel);
new_head->set_unswitch_count(head->unswitch_count()); // Preserve
_igvn.register_new_node_with_optimizer(new_head);
assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
first_not_peeled->set_req(0, new_head);
set_loop(new_head, loop);
loop->_body.push(new_head);
not_peel.set(new_head->_idx);
set_idom(new_head, last_peel, dom_depth(first_not_peeled));
set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
while (sink_list.size() > 0) {
Node* n = sink_list.pop();
set_ctrl(n, new_head);
}
assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
clone_loop( loop, old_new, dd );
const uint clone_exit_idx = 1;
const uint orig_exit_idx = 2;
assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
Node* head_clone = old_new[head->_idx];
LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
Node* orig_tail_clone = head_clone->in(2);
// Add phi if "def" node is in peel set and "use" is not
for(i = 0; i < peel_list.size(); i++ ) {
Node *def = peel_list.at(i);
if (!def->is_CFG()) {
for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
Node *use = def->fast_out(j);
if (has_node(use) && use->in(0) != C->top() &&
(!peel.test(use->_idx) ||
(use->is_Phi() && use->in(0) == head)) ) {
worklist.push(use);
}
}
while( worklist.size() ) {
Node *use = worklist.pop();
for (uint j = 1; j < use->req(); j++) {
Node* n = use->in(j);
if (n == def) {
// "def" is in peel set, "use" is not in peel set
// or "use" is in the entry boundary (a phi) of the peel set
Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
if ( loop->is_member(get_loop( use_c )) ) {
// use is in loop
if (old_new[use->_idx] != NULL) { // null for dead code
Node* use_clone = old_new[use->_idx];
_igvn.replace_input_of(use, j, C->top());
insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
}
} else {
assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
// use is not in the loop, check if the live range includes the cut
Node* lp_if = use_c->in(orig_exit_idx)->in(0);
if (not_peel.test(lp_if->_idx)) {
assert(j == orig_exit_idx, "use from original loop");
insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
}
}
}
}
}
}
}
// Step 3b: retarget control
// Redirect control to the new loop head if a cloned node in
// the not_peeled region has control that points into the peeled region.
// This necessary because the cloned peeled region will be outside
// the loop.
// from to
// cloned-peeled <---+
// new_head_clone: | <--+
// cloned-not_peeled in(0) in(0)
// orig-peeled
for(i = 0; i < loop->_body.size(); i++ ) {
Node *n = loop->_body.at(i);
if (!n->is_CFG() && n->in(0) != NULL &&
not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
Node* n_clone = old_new[n->_idx];
_igvn.replace_input_of(n_clone, 0, new_head_clone);
}
}
// Backedge of the surviving new_head (the clone) is original last_peel
_igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
// Cut first node in original not_peel set
_igvn.rehash_node_delayed(new_head); // Multiple edge updates:
new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
// Copy head_clone back-branch info to original head
// and remove original head's loop entry and
// clone head's back-branch
_igvn.rehash_node_delayed(head); // Multiple edge updates
head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
head->set_req(LoopNode::LoopBackControl, C->top());
_igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
// Similarly modify the phis
for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
Node* use = head->fast_out(k);
if (use->is_Phi() && use->outcnt() > 0) {
Node* use_clone = old_new[use->_idx];
_igvn.rehash_node_delayed(use); // Multiple edge updates
use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
use->set_req(LoopNode::LoopBackControl, C->top());
_igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
}
}
// Step 4: update dominator tree and dominator depth
set_idom(head, orig_tail_clone, dd);
recompute_dom_depth();
// Inhibit more partial peeling on this loop
new_head_clone->set_partial_peel_loop();
C->set_major_progress();
#if !defined(PRODUCT)
if (TracePartialPeeling) {
tty->print_cr("\nafter partial peel one iteration");
Node_List wl(area);
Node* t = last_peel;
while (true) {
wl.push(t);
if (t == head_clone) break;
t = idom(t);
}
while (wl.size() > 0) {
Node* tt = wl.pop();
if (tt == head) tty->print_cr("orig head");
else if (tt == new_head_clone) tty->print_cr("new head");
else if (tt == head_clone) tty->print_cr("clone head");
tt->dump();
}
}
#endif
return true;
}
//------------------------------reorg_offsets----------------------------------
// Reorganize offset computations to lower register pressure. Mostly
// prevent loop-fallout uses of the pre-incremented trip counter (which are
// then alive with the post-incremented trip counter forcing an extra
// register move)
void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
// Perform it only for canonical counted loops.
// Loop's shape could be messed up by iteration_split_impl.
if (!loop->_head->is_CountedLoop())
return;
if (!loop->_head->as_Loop()->is_valid_counted_loop())
return;
CountedLoopNode *cl = loop->_head->as_CountedLoop();
CountedLoopEndNode *cle = cl->loopexit();
Node *exit = cle->proj_out(false);
Node *phi = cl->phi();
// Check for the special case of folks using the pre-incremented
// trip-counter on the fall-out path (forces the pre-incremented
// and post-incremented trip counter to be live at the same time).
// Fix this by adjusting to use the post-increment trip counter.
bool progress = true;
while (progress) {
progress = false;
for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
Node* use = phi->fast_out(i); // User of trip-counter
if (!has_ctrl(use)) continue;
Node *u_ctrl = get_ctrl(use);
if (use->is_Phi()) {
u_ctrl = NULL;
for (uint j = 1; j < use->req(); j++)
if (use->in(j) == phi)
u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
}
IdealLoopTree *u_loop = get_loop(u_ctrl);
// Look for loop-invariant use
if (u_loop == loop) continue;
if (loop->is_member(u_loop)) continue;
// Check that use is live out the bottom. Assuming the trip-counter
// update is right at the bottom, uses of of the loop middle are ok.
if (dom_lca(exit, u_ctrl) != exit) continue;
// Hit! Refactor use to use the post-incremented tripcounter.
// Compute a post-increment tripcounter.
Node *opaq = new (C) Opaque2Node( C, cle->incr() );
register_new_node( opaq, u_ctrl );
Node *neg_stride = _igvn.intcon(-cle->stride_con());
set_ctrl(neg_stride, C->root());
Node *post = new (C) AddINode( opaq, neg_stride);
register_new_node( post, u_ctrl );
_igvn.rehash_node_delayed(use);
for (uint j = 1; j < use->req(); j++) {
if (use->in(j) == phi)
use->set_req(j, post);
}
// Since DU info changed, rerun loop
progress = true;
break;
}
}
}
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