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*/
//============================================================================= //------------------------------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;
}
// Splitting range check CastIIs through a loop induction Phi can // cause new Phis to be created that are left unrelated to the loop // induction Phi and prevent optimizations (vectorization) if (n->Opcode() == Op_CastII && region->is_CountedLoop() &&
n->in(1) == region->as_CountedLoop()->phi()) { return NULL;
}
// Bail out if 'n' is a Div or Mod node whose zero check was removed earlier (i.e. control is NULL) and its divisor is an induction variable // phi p of a trip-counted (integer) loop whose inputs could be zero (include zero in their type range). p could have a more precise type // range that does not necessarily include all values of its inputs. Since each of these inputs will be a divisor of the newly cloned nodes // of 'n', we need to bail out of one of these divisors could be zero (zero in its type range). if ((n->Opcode() == Op_DivI || n->Opcode() == Op_ModI) && n->in(0) == NULL
&& region->is_CountedLoop() && n->in(2) == region->as_CountedLoop()->phi()) {
Node* phi = region->as_CountedLoop()->phi(); for (uint i = 1; i < phi->req(); i++) { if (_igvn.type(phi->in(i))->filter_speculative(TypeInt::ZERO) != Type::TOP) { // Zero could be a possible value but we already removed the zero check. Bail out to avoid a possible division by zero at a later point. 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 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(IfProjNode* prevdom, IfNode* iff, bool flip, bool exclude_loop_predicate) { if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
// prevdom is the dominating projection of the dominating test.
assert(iff->Opcode() == Op_If ||
iff->Opcode() == Op_CountedLoopEnd ||
iff->Opcode() == Op_LongCountedLoopEnd ||
iff->Opcode() == Op_RangeCheck, "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->proj_out_or_null(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->proj_out(1 - dp_proj->_con)->as_Proj(); if (exclude_loop_predicate &&
(unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_profile_predicate) != NULL ||
unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) { // If this is a range check (IfNode::is_range_check), do not // reorder because Compile::allow_range_check_smearing might have // changed the check. 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 // Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check. if (cd->depends_only_on_test() && _igvn.no_dependent_zero_check(cd)) {
assert(cd->in(0) == dp, "");
_igvn.replace_input_of(cd, 0, prevdom);
set_early_ctrl(cd, false);
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(AddPNode::Base)) != n_ctrl &&
get_ctrl(m->in(AddPNode::Address)) != n_ctrl &&
get_ctrl(m->in(AddPNode::Offset)) != n_ctrl) { // Move the AddP up to the dominating point. That's fine because control of m's inputs // must dominate get_ctrl(m) == n_ctrl and we just checked that the input controls are != n_ctrl.
Node* c = find_non_split_ctrl(idom(n_ctrl)); if (c->is_OuterStripMinedLoop()) {
c->as_Loop()->verify_strip_mined(1);
c = c->in(LoopNode::EntryControl);
}
set_ctrl_and_loop(m, c); continue;
} return NULL;
}
assert(n->is_Phi() || m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
}
return n_ctrl;
}
// Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
Node* PhaseIdealLoop::remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt) {
assert(bt == T_INT || bt == T_LONG, "only for integers"); int n_op = n->Opcode();
if (n_op == Op_LShift(bt)) { // 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 != NULL && 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); 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_Sub(bt) &&
_igvn.type(add->in(1)) != TypeInteger::zero(bt)) {
assert(add->Opcode() == Op_SubI || add->Opcode() == Op_SubL, "");
Node* zero = _igvn.integercon(0, bt);
set_ctrl(zero, C->root());
Node* neg = SubNode::make(zero, add->in(2), bt);
register_new_node(neg, get_ctrl(add->in(2)));
add = AddNode::make(add->in(1), neg, bt);
register_new_node(add, add_ctrl);
} if (add->Opcode() != Op_Add(bt)) return NULL;
assert(add->Opcode() == Op_AddI || add->Opcode() == Op_AddL, ""); // 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_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);
} elseif (add_var_loop != n_loop) { // 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?
}
//------------------------------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;
// 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
}
Node* res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_INT); if (res != NULL) { return res;
}
res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_LONG); if (res != NULL) { return res;
}
//------------------------------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 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_DOUBLE: case T_FLOAT: if (C->use_cmove()) { continue; //TODO: maybe we want to add some cost
}
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;
}
}
}
}//for
Node* bol = iff->in(1); if (bol->Opcode() == Op_Opaque4) { return NULL; // Ignore loop predicate checks (the Opaque4 ensures they will go away)
}
assert(bol->Opcode() == Op_Bool, "Unexpected node"); int cmp_op = bol->in(1)->Opcode(); if (cmp_op == Op_SubTypeCheck) { // SubTypeCheck expansion expects an IfNode return NULL;
} // 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 (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) { //keep going
} elseif (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);
Node_List wq; 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 || _igvn.type(phi) == Type::TOP) { break;
} if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); } // Move speculative ops
wq.push(phi); while (wq.size() > 0) {
Node *n = wq.pop(); for (uint j = 1; j < n->req(); j++) {
Node* m = n->in(j); if (m != NULL && !is_dominator(get_ctrl(m), cmov_ctrl)) { #ifndef PRODUCT if (PrintOpto && VerifyLoopOptimizations) {
tty->print(" speculate: ");
m->dump();
} #endif
set_ctrl(m, cmov_ctrl);
wq.push(m);
}
}
}
Node *cmov = CMoveNode::make(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);
}
staticvoid enqueue_cfg_uses(Node* m, Unique_Node_List& wq) { for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
Node* u = m->fast_out(i); if (u->is_CFG()) { if (u->Opcode() == Op_NeverBranch) {
u = ((NeverBranchNode*)u)->proj_out(0);
enqueue_cfg_uses(u, wq);
} else {
wq.push(u);
}
}
}
}
// Try moving a store out of a loop, right before the loop
Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) { // Store has to be first in the loop body
IdealLoopTree *n_loop = get_loop(n_ctrl); if (n->is_Store() && n_loop != _ltree_root &&
n_loop->is_loop() && n_loop->_head->is_Loop() &&
n->in(0) != NULL) {
Node* address = n->in(MemNode::Address);
Node* value = n->in(MemNode::ValueIn);
Node* mem = n->in(MemNode::Memory);
IdealLoopTree* address_loop = get_loop(get_ctrl(address));
IdealLoopTree* value_loop = get_loop(get_ctrl(value));
// - address and value must be loop invariant // - memory must be a memory Phi for the loop // - Store must be the only store on this memory slice in the // loop: if there's another store following this one then value // written at iteration i by the second store could be overwritten // at iteration i+n by the first store: it's not safe to move the // first store out of the loop // - nothing must observe the memory Phi: it guarantees no read // before the store, we are also guaranteed the store post // dominates the loop head (ignoring a possible early // exit). Otherwise there would be extra Phi involved between the // loop's Phi and the store. // - there must be no early exit from the loop before the Store // (such an exit most of the time would be an extra use of the // memory Phi but sometimes is a bottom memory Phi that takes the // store as input).
assert(n_loop->_tail != NULL, "need a tail");
assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
// Verify that there's no early exit of the loop before the store. bool ctrl_ok = false;
{ // Follow control from loop head until n, we exit the loop or // we reach the tail
ResourceMark rm;
Unique_Node_List wq;
wq.push(n_loop->_head);
for (uint next = 0; next < wq.size(); ++next) {
Node *m = wq.at(next); if (m == n->in(0)) {
ctrl_ok = true; continue;
}
assert(!has_ctrl(m), "should be CFG"); if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
ctrl_ok = false; break;
}
enqueue_cfg_uses(m, wq); if (wq.size() > 10) {
ctrl_ok = false; break;
}
}
} if (ctrl_ok) { // move the Store
_igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
_igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
_igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl)); // Disconnect the phi now. An empty phi can confuse other // optimizations in this pass of loop opts.
_igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
n_loop->_body.yank(mem);
set_ctrl_and_loop(n, n->in(0));
return n;
}
}
} return NULL;
}
// Try moving a store out of a loop, right after the loop void PhaseIdealLoop::try_move_store_after_loop(Node* n) { if (n->is_Store() && n->in(0) != NULL) {
Node *n_ctrl = get_ctrl(n);
IdealLoopTree *n_loop = get_loop(n_ctrl); // Store must be in a loop if (n_loop != _ltree_root && !n_loop->_irreducible) {
Node* address = n->in(MemNode::Address);
Node* value = n->in(MemNode::ValueIn);
IdealLoopTree* address_loop = get_loop(get_ctrl(address)); // address must be loop invariant if (!n_loop->is_member(address_loop)) { // Store must be last on this memory slice in the loop and // nothing in the loop must observe it
Node* phi = NULL; for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
Node* u = n->fast_out(i); if (has_ctrl(u)) { // control use?
IdealLoopTree *u_loop = get_loop(get_ctrl(u)); if (!n_loop->is_member(u_loop)) { continue;
} if (u->is_Phi() && u->in(0) == n_loop->_head) {
assert(_igvn.type(u) == Type::MEMORY, "bad phi"); // multiple phis on the same slice are possible if (phi != NULL) { return;
}
phi = u; continue;
}
} return;
} if (phi != NULL) { // Nothing in the loop before the store (next iteration) // must observe the stored value bool mem_ok = true;
{
ResourceMark rm;
Unique_Node_List wq;
wq.push(phi); for (uint next = 0; next < wq.size() && mem_ok; ++next) {
Node *m = wq.at(next); for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
Node* u = m->fast_out(i); if (u->is_Store() || u->is_Phi()) { if (u != n) {
wq.push(u);
mem_ok = (wq.size() <= 10);
}
} else {
mem_ok = false; break;
}
}
}
} if (mem_ok) { // Move the store out of the loop if the LCA of all // users (except for the phi) is outside the loop.
Node* hook = new Node(1);
hook->init_req(0, n_ctrl); // Add an input to prevent hook from being dead
_igvn.rehash_node_delayed(phi); int count = phi->replace_edge(n, hook, &_igvn);
assert(count > 0, "inconsistent phi");
// Compute latest point this store can go
Node* lca = get_late_ctrl(n, get_ctrl(n)); if (lca->is_OuterStripMinedLoop()) {
lca = lca->in(LoopNode::EntryControl);
} if (n_loop->is_member(get_loop(lca))) { // LCA is in the loop - bail out
_igvn.replace_node(hook, n); return;
} #ifdef ASSERT if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
n_loop->_head->as_Loop()->verify_strip_mined(1);
Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
IdealLoopTree* outer_loop = get_loop(outer);
assert(n_loop->_parent == outer_loop, "broken loop tree");
assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
} #endif
lca = place_outside_loop(lca, n_loop);
assert(!n_loop->is_member(get_loop(lca)), "control must not be back in the loop");
assert(get_loop(lca)->_nest < n_loop->_nest || lca->in(0)->Opcode() == Op_NeverBranch, "must not be moved into inner loop");
// Move store out of the loop
_igvn.replace_node(hook, n->in(MemNode::Memory));
_igvn.replace_input_of(n, 0, lca);
set_ctrl_and_loop(n, lca);
// Disconnect the phi now. An empty phi can confuse other // optimizations in this pass of loop opts.. if (phi->in(LoopNode::LoopBackControl) == phi) {
_igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
n_loop->_body.yank(phi);
}
}
}
}
}
}
}
//------------------------------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->is_Opaque1()) { // Opaque nodes cannot be mod'd 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
}
Node* res = try_move_store_before_loop(n, n_ctrl); if (res != NULL) { return n;
}
// Attempt to remix address expressions for loop invariants
Node *m = remix_address_expressions( n ); if( m ) return m;
if (n_op == Op_AddI) {
Node *nn = convert_add_to_muladd( n ); if ( nn ) return nn;
}
if (n->is_ConstraintCast()) {
Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this); // ConstraintCastNode::dominating_cast() uses node control input to determine domination. // Node control inputs don't necessarily agree with loop control info (due to // transformations happened in between), thus additional dominance check is needed // to keep loop info valid. if (dom_cast != NULL && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
_igvn.replace_node(n, dom_cast); return dom_cast;
}
}
// 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_blk->is_Loop() && n_blk->as_Loop()->is_loop_nest_inner_loop())) && n->Opcode() == Op_AddI) ||
(n_blk->is_LongCountedLoop() && n->Opcode() == Op_AddL)) { return n;
} // Pushing a shift through the iv Phi can get in the way of addressing optimizations or range check elimination if (n_blk->is_BaseCountedLoop() && n->Opcode() == Op_LShift(n_blk->as_BaseCountedLoop()->bt()) &&
n->in(1) == n_blk->as_BaseCountedLoop()->phi()) { 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_BaseCountedLoop()) {
IdealLoopTree *lp = get_loop(n_blk); if (lp && lp->_rce_candidate) { return n;
}
}
if (must_throttle_split_if()) return n;
// 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;
}
staticbool 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 = C->max_node_limit() - C->live_nodes(); if (weight * 8 > nodes_left) { if (PrintOpto) {
tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
} returntrue;
} else { returnfalse;
}
}
staticbool 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. #ifdef _LP64 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->Opcode() == Op_ConvI2L) returnfalse; if (m->is_CastII()) { returnfalse;
}
}
}
} #endif returntrue;
}
//------------------------------place_outside_loop--------------------------------- // Place some computation outside of this loop on the path to the use passed as argument
Node* PhaseIdealLoop::place_outside_loop(Node* useblock, IdealLoopTree* loop) const {
Node* head = loop->_head;
assert(!loop->is_member(get_loop(useblock)), "must be outside loop"); if (head->is_Loop() && head->as_Loop()->is_strip_mined()) {
loop = loop->_parent;
assert(loop->_head->is_OuterStripMinedLoop(), "malformed strip mined loop");
}
// Pick control right outside the loop for (;;) {
Node* dom = idom(useblock); if (loop->is_member(get_loop(dom)) || // NeverBranch nodes are not assigned to the loop when constructed
(dom->Opcode() == Op_NeverBranch && loop->is_member(get_loop(dom->in(0))))) { break;
}
useblock = dom;
}
assert(find_non_split_ctrl(useblock) == useblock, "should be non split control"); return useblock;
}
bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) { if (!n->is_If() || n->is_BaseCountedLoopEnd()) { returnfalse;
} if (!n->in(0)->is_Region()) { returnfalse;
}
Node* region = n->in(0);
Node* dom = idom(region); if (!dom->is_If() || dom->in(1) != n->in(1)) { returnfalse;
}
IfNode* dom_if = dom->as_If();
Node* proj_true = dom_if->proj_out(1);
Node* proj_false = dom_if->proj_out(0);
for (uint i = 1; i < region->req(); i++) { if (is_dominator(proj_true, region->in(i))) { continue;
} if (is_dominator(proj_false, region->in(i))) { continue;
} returnfalse;
}
returntrue;
}
bool PhaseIdealLoop::can_split_if(Node* n_ctrl) { if (must_throttle_split_if()) { returnfalse;
}
// Do not do 'split-if' if irreducible loops are present. if (_has_irreducible_loops) { returnfalse;
}
if (merge_point_too_heavy(C, n_ctrl)) { returnfalse;
}
// 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()) { returnfalse;
}
}
// 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) { returnfalse;
}
}
// Check for safety of the merge point. if (!merge_point_safe(n_ctrl)) { returnfalse;
}
returntrue;
}
// Detect if the node is the inner strip-mined loop // Return: NULL if it's not the case, or the exit of outer strip-mined loop static Node* is_inner_of_stripmined_loop(const Node* out) {
Node* out_le = NULL;
if (out->is_CountedLoopEnd()) { const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
//------------------------------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()) {
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 (!can_split_if(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
}
} elseif (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
}
// When is split-if profitable? Every 'win' on means some control flow // goes dead, so it's almost always a win. int policy = 0; // 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");
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;
}
// Two identical ifs back to back can be merged if (try_merge_identical_ifs(n)) { 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 ||
n_op == Op_RangeCheck) {
Node *bol = n->in(1);
uint max = bol->outcnt(); // Check for same test used more than once? 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 &&
safe_for_if_replacement(dom)) { // It's invalid to move control dependent data nodes in the inner // strip-mined loop, because: // 1) break validation of LoopNode::verify_strip_mined() // 2) move code with side-effect in strip-mined loop // Move to the exit of outer strip-mined loop in that case.
Node* out_le = is_inner_of_stripmined_loop(dom); if (out_le != NULL) {
prevdom = out_le;
} // 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->as_IfProj(), n->as_If(), false, true); #ifndef PRODUCT if( VerifyLoopOptimizations ) verify(); #endif return;
}
prevdom = dom;
dom = idom(prevdom);
}
}
}
try_sink_out_of_loop(n);
try_move_store_after_loop(n);
}
// Transform: // // if (some_condition) { // // body 1 // } else { // // body 2 // } // if (some_condition) { // // body 3 // } else { // // body 4 // } // // into: // // // if (some_condition) { // // body 1 // // body 3 // } else { // // body 2 // // body 4 // } bool PhaseIdealLoop::try_merge_identical_ifs(Node* n) { if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
Node *n_ctrl = n->in(0);
IfNode* dom_if = idom(n_ctrl)->as_If();
ProjNode* dom_proj_true = dom_if->proj_out(1);
ProjNode* dom_proj_false = dom_if->proj_out(0);
// Now split the IF
RegionNode* new_false_region;
RegionNode* new_true_region;
do_split_if(n, &new_false_region, &new_true_region);
assert(new_false_region->req() == new_true_region->req(), ""); #ifdef ASSERT for (uint i = 1; i < new_false_region->req(); ++i) {
assert(new_false_region->in(i)->in(0) == new_true_region->in(i)->in(0), "unexpected shape following split if");
assert(i == new_false_region->req() - 1 || new_false_region->in(i)->in(0)->in(1) == new_false_region->in(i + 1)->in(0)->in(1), "unexpected shape following split if");
} #endif
assert(new_false_region->in(1)->in(0)->in(1) == dom_if->in(1), "dominating if and dominated if after split must share test");
// We now have: // if (some_condition) { // // body 1 // if (some_condition) { // body3: // new_true_region // // body3 // } else { // goto body4; // } // } else { // // body 2 // if (some_condition) { // goto body3; // } else { // body4: // new_false_region // // body4; // } // } //
// clone pinned nodes thru the resulting regions
push_pinned_nodes_thru_region(dom_if, new_true_region);
push_pinned_nodes_thru_region(dom_if, new_false_region);
// Optimize out the cloned ifs. Because pinned nodes were cloned, this also allows a CastPP that would be dependent // on a projection of n to have the dom_if as a control dependency. We don't want the CastPP to end up with an // unrelated control dependency. for (uint i = 1; i < new_false_region->req(); i++) { if (is_dominator(dom_proj_true, new_false_region->in(i))) {
dominated_by(dom_proj_true->as_IfProj(), new_false_region->in(i)->in(0)->as_If(), false, false);
} else {
assert(is_dominator(dom_proj_false, new_false_region->in(i)), "bad if");
dominated_by(dom_proj_false->as_IfProj(), new_false_region->in(i)->in(0)->as_If(), false, false);
}
} returntrue;
} returnfalse;
}
void PhaseIdealLoop::push_pinned_nodes_thru_region(IfNode* dom_if, Node* region) { for (DUIterator i = region->outs(); region->has_out(i); i++) {
Node* u = region->out(i); if (!has_ctrl(u) || u->is_Phi() || !u->depends_only_on_test() || !_igvn.no_dependent_zero_check(u)) { continue;
}
assert(u->in(0) == region, "not a control dependent node?");
uint j = 1; for (; j < u->req(); ++j) {
Node* in = u->in(j); if (!is_dominator(ctrl_or_self(in), dom_if)) { break;
}
} if (j == u->req()) {
Node *phi = PhiNode::make_blank(region, u); for (uint k = 1; k < region->req(); ++k) {
Node* clone = u->clone();
clone->set_req(0, region->in(k));
register_new_node(clone, region->in(k));
phi->init_req(k, clone);
}
register_new_node(phi, region);
_igvn.replace_node(u, phi);
--i;
}
}
}
bool PhaseIdealLoop::safe_for_if_replacement(const Node* dom) const { if (!dom->is_CountedLoopEnd()) { returntrue;
}
CountedLoopEndNode* le = dom->as_CountedLoopEnd();
CountedLoopNode* cl = le->loopnode(); if (cl == NULL) { returntrue;
} if (!cl->is_main_loop()) { returntrue;
} if (cl->is_canonical_loop_entry() == NULL) { returntrue;
} // Further unrolling is possible so loop exit condition might change returnfalse;
}
// 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. void PhaseIdealLoop::try_sink_out_of_loop(Node* n) { if (has_ctrl(n) &&
!n->is_Phi() &&
!n->is_Bool() &&
!n->is_Proj() &&
!n->is_MergeMem() &&
!n->is_CMove() &&
n->Opcode() != Op_Opaque4 &&
!n->is_Type()) {
Node *n_ctrl = get_ctrl(n);
IdealLoopTree *n_loop = get_loop(n_ctrl);
if (n->in(0) != NULL) {
IdealLoopTree* loop_ctrl = get_loop(n->in(0)); if (n_loop != loop_ctrl && n_loop->is_member(loop_ctrl)) { // n has a control input inside a loop but get_ctrl() is member of an outer loop. This could happen, for example, // for Div nodes inside a loop (control input inside loop) without a use except for an UCT (outside the loop). // Rewire control of n to right outside of the loop, regardless if its input(s) are later sunk or not.
_igvn.replace_input_of(n, 0, place_outside_loop(n_ctrl, loop_ctrl));
}
} if (n_loop != _ltree_root && n->outcnt() > 1) { // Compute early control: needed for anti-dependence analysis. It's also possible that as a result of // previous transformations in this loop opts round, the node can be hoisted now: early control will tell us.
Node* early_ctrl = compute_early_ctrl(n, n_ctrl); if (n_loop->is_member(get_loop(early_ctrl)) && // check that this one can't be hoisted now
ctrl_of_all_uses_out_of_loop(n, early_ctrl, n_loop)) { // All uses in outer loops!
assert(!n->is_Store() && !n->is_LoadStore(), "no node with a side effect");
Node* outer_loop_clone = NULL; 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); // Find control for 'x' next to use but not inside inner loops.
x_ctrl = place_outside_loop(x_ctrl, n_loop);
--j;
} else { // Normal use if (has_ctrl(u)) {
x_ctrl = get_ctrl(u);
} else {
x_ctrl = u->in(0);
} // Find control for 'x' next to use but not inside inner loops.
x_ctrl = place_outside_loop(x_ctrl, n_loop); // Replace all uses if (u->is_ConstraintCast() && u->bottom_type()->higher_equal(_igvn.type(n)) && u->in(0) == x_ctrl) { // If we're sinking a chain of data nodes, we might have inserted a cast to pin the use which is not necessary // anymore now that we're going to pin n as well
_igvn.replace_node(u, x);
--j;
} else { int nb = u->replace_edge(n, x, &_igvn);
j -= nb;
}
}
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).
assert(x_ctrl == get_late_ctrl_with_anti_dep(x->as_Load(), early_ctrl, x_ctrl), "anti-dependences were already checked");
IdealLoopTree* x_loop = get_loop(x_ctrl);
Node* x_head = x_loop->_head; if (x_head->is_Loop() && x_head->is_OuterStripMinedLoop()) { // Do not add duplicate LoadNodes to the outer strip mined loop if (outer_loop_clone != NULL) {
_igvn.replace_node(x, outer_loop_clone); continue;
}
outer_loop_clone = x;
}
x->set_req(0, x_ctrl);
} elseif (n->in(0) != NULL){
x->set_req(0, x_ctrl);
}
assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
assert(!n_loop->is_member(get_loop(x_ctrl)), "should have moved out of loop");
register_new_node(x, x_ctrl);
// Chain of AddP: (AddP base (AddP base )) must keep the same base after sinking so: // 1- We don't add a CastPP here when the first one is sunk so if the second one is not, their bases remain // the same. // (see 2- below)
assert(!x->is_AddP() || !x->in(AddPNode::Address)->is_AddP() ||
x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base) ||
!x->in(AddPNode::Address)->in(AddPNode::Base)->eqv_uncast(x->in(AddPNode::Base)), "unexpected AddP shape"); if (x->in(0) == NULL && !x->is_DecodeNarrowPtr() &&
!(x->is_AddP() && x->in(AddPNode::Address)->is_AddP() && x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base))) {
assert(!x->is_Load(), "load should be pinned"); // Use a cast node to pin clone out of loop
Node* cast = NULL; for (uint k = 0; k < x->req(); k++) {
Node* in = x->in(k); if (in != NULL && n_loop->is_member(get_loop(get_ctrl(in)))) { const Type* in_t = _igvn.type(in);
cast = ConstraintCastNode::make_cast_for_type(x_ctrl, in, in_t, ConstraintCastNode::UnconditionalDependency);
} if (cast != NULL) {
register_new_node(cast, x_ctrl);
x->replace_edge(in, cast); // Chain of AddP: // 2- A CastPP of the base is only added now that both AddP nodes are sunk if (x->is_AddP() && k == AddPNode::Base) { for (DUIterator_Fast imax, i = x->fast_outs(imax); i < imax; i++) {
Node* u = x->fast_out(i); if (u->is_AddP() && u->in(AddPNode::Base) == n->in(AddPNode::Base)) {
_igvn.replace_input_of(u, AddPNode::Base, cast);
assert(u->find_out_with(Op_AddP) == NULL, "more than 2 chained AddP nodes?");
}
}
} break;
}
}
assert(cast != NULL, "must have added a cast to pin the node");
}
}
_igvn.remove_dead_node(n);
}
_dom_lca_tags_round = 0;
}
}
}
// Compute the early control of a node by following its inputs until we reach // nodes that are pinned. Then compute the LCA of the control of all pinned nodes.
Node* PhaseIdealLoop::compute_early_ctrl(Node* n, Node* n_ctrl) {
Node* early_ctrl = NULL;
ResourceMark rm;
Unique_Node_List wq;
wq.push(n); for (uint i = 0; i < wq.size(); i++) {
Node* m = wq.at(i);
Node* c = NULL; if (m->is_CFG()) {
c = m;
} elseif (m->pinned()) {
c = m->in(0);
} else { for (uint j = 0; j < m->req(); j++) {
Node* in = m->in(j); if (in != NULL) {
wq.push(in);
}
}
} if (c != NULL) {
assert(is_dominator(c, n_ctrl), "control input must dominate current control"); if (early_ctrl == NULL || is_dominator(early_ctrl, c)) {
early_ctrl = c;
}
}
}
assert(is_dominator(early_ctrl, n_ctrl), "early control must dominate current control"); return early_ctrl;
}
bool PhaseIdealLoop::ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop) { for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
Node* u = n->fast_out(i); if (u->is_Opaque1()) { returnfalse; // Found loop limit, bugfix for 4677003
} // We can't reuse tags in PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal() so make sure calls to // get_late_ctrl_with_anti_dep() use their own tag
_dom_lca_tags_round++;
assert(_dom_lca_tags_round != 0, "shouldn't wrap around");
if (u->is_Phi()) { for (uint j = 1; j < u->req(); ++j) { if (u->in(j) == n && !ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, u->in(0)->in(j))) { returnfalse;
}
}
} else {
Node* ctrl = has_ctrl(u) ? get_ctrl(u) : u->in(0); if (!ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, ctrl)) { returnfalse;
}
}
} returntrue;
}
bool PhaseIdealLoop::ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl) { if (n->is_Load()) {
ctrl = get_late_ctrl_with_anti_dep(n->as_Load(), n_ctrl, ctrl);
}
IdealLoopTree *u_loop = get_loop(ctrl); if (u_loop == n_loop) { returnfalse; // Found loop-varying use
} if (n_loop->is_member(u_loop)) { returnfalse; // Found use in inner loop
} returntrue;
}
//------------------------------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* root = C->root();
visited.set(root->_idx); // first, mark root as visited // Do pre-visit work for root
Node* n = split_if_with_blocks_pre(root);
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 (must_throttle_split_if()) {
nstack.clear();
} 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.
Node* PhaseIdealLoop::clone_iff(PhiNode* phi) {
// 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()));
} else {
assert(b->is_Bool() || b->Opcode() == Op_Opaque4, "");
}
}
//------------------------------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) {
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()));
} 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 PhiNode( phi->in(0), Type::TOP );
PhiNode *phi2 = new 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_speculative(n1->bottom_type()));
phi2->set_type(phi2->type()->meet_speculative(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));
//------------------------------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);
}
}
void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
IdealLoopTree* loop, IdealLoopTree* outer_loop,
Node_List*& split_if_set, Node_List*& split_bool_set,
Node_List*& split_cex_set, Node_List& worklist,
uint new_counter, CloneLoopMode mode) {
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. #ifdef ASSERT if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == NULL) {
Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
assert(mode != IgnoreStripMined, "incorrect cloning mode");
assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root(), "missed a node");
} #endif if (!loop->is_member(use_loop) && !outer_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. // Loop predicate If node connects to Bool node through Opaque1 node. // // If the use is an AllocateArray through its ValidLengthTest input, // make sure the Bool/Cmp input is cloned down to avoid a Phi between // the AllocateArray node and its ValidLengthTest input that could cause // split if to break. if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use) || use->Opcode() == Op_Opaque4 ||
(use->Opcode() == Op_AllocateArray && use->in(AllocateNode::ValidLengthTest) == old)) { // 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();
}
split_if_set->push(use);
} if (use->is_Bool()) { if (!split_bool_set) {
split_bool_set = new Node_List();
}
split_bool_set->push(use);
} if (use->Opcode() == Op_CreateEx) { if (!split_cex_set) {
split_cex_set = new Node_List();
}
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)) && !outer_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;
}
// If use is referenced through control edge... (idx == 0) if (mode == IgnoreStripMined && idx == 0) {
LoopNode *head = loop->_head->as_Loop(); if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) { // That node is outside the inner loop, leave it outside the // outer loop as well to not confuse verification code.
assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
_igvn.replace_input_of(use, 0, head->outer_loop_exit()); continue;
}
}
while(!outer_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 );
}
}
}
staticvoid collect_nodes_in_outer_loop_not_reachable_from_sfpt(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop, const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase, bool check_old_new) { for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
Node* u = n->fast_out(j);
assert(check_old_new || old_new[u->_idx] == NULL, "shouldn't have been cloned"); if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == NULL)) {
Node* c = phase->get_ctrl(u);
IdealLoopTree* u_loop = phase->get_loop(c);
assert(!loop->is_member(u_loop) || !loop->_body.contains(u), "can be in outer loop or out of both loops only"); if (!loop->is_member(u_loop)) { if (outer_loop->is_member(u_loop)) {
wq.push(u);
} else { // nodes pinned with control in the outer loop but not referenced from the safepoint must be moved out of // the outer loop too
Node* u_c = u->in(0); if (u_c != NULL) {
IdealLoopTree* u_c_loop = phase->get_loop(u_c); if (outer_loop->is_member(u_c_loop) && !loop->is_member(u_c_loop)) {
wq.push(u);
}
}
}
}
}
}
}
_igvn.register_new_node_with_optimizer(new_l);
_igvn.register_new_node_with_optimizer(new_tail);
_igvn.register_new_node_with_optimizer(new_le);
} else {
Node *newhead = old_new[loop->_head->_idx];
newhead->as_Loop()->clear_strip_mined();
_igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
} // Look at data node that were assigned a control in the outer // loop: they are kept in the outer loop by the safepoint so start // from the safepoint node's inputs.
IdealLoopTree* outer_loop = get_loop(l);
Node_Stack stack(2);
stack.push(sfpt, 1);
uint new_counter = C->unique(); while (stack.size() > 0) {
Node* n = stack.node();
uint i = stack.index(); while (i < n->req() &&
(n->in(i) == NULL ||
!has_ctrl(n->in(i)) ||
get_loop(get_ctrl(n->in(i))) != outer_loop ||
(old_new[n->in(i)->_idx] != NULL && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
i++;
} if (i < n->req()) {
stack.set_index(i+1);
stack.push(n->in(i), 0);
} else {
assert(old_new[n->_idx] == NULL || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
Node* m = n == sfpt ? new_sfpt : n->clone(); if (m != NULL) { for (uint i = 0; i < n->req(); i++) { if (m->in(i) != NULL && old_new[m->in(i)->_idx] != NULL) {
m->set_req(i, old_new[m->in(i)->_idx]);
}
}
} else {
assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
} if (n != sfpt) {
extra_data_nodes.push(n);
_igvn.register_new_node_with_optimizer(m);
assert(get_ctrl(n) == cle_out, "what other control?");
set_ctrl(m, new_cle_out);
old_new.map(n->_idx, m);
}
stack.pop();
}
} if (mode == CloneIncludesStripMined) {
_igvn.register_new_node_with_optimizer(new_sfpt);
_igvn.register_new_node_with_optimizer(new_cle_out);
} // Some other transformation may have pessimistically assigned some // data nodes to the outer loop. Set their control so they are out // of the outer loop.
ResourceMark rm;
Unique_Node_List wq; for (uint i = 0; i < extra_data_nodes.size(); i++) {
Node* old = extra_data_nodes.at(i);
collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
}
for (uint i = 0; i < loop->_body.size(); i++) {
Node* old = loop->_body.at(i);
collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
}
Node* new_ctrl = cl->outer_loop_exit();
assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest"); for (uint i = 0; i < wq.size(); i++) {
Node* n = wq.at(i);
set_ctrl(n, new_ctrl); if (n->in(0) != NULL) {
_igvn.replace_input_of(n, 0, new_ctrl);
}
collect_nodes_in_outer_loop_not_reachable_from_sfpt(n, loop, outer_loop, old_new, wq, this, false);
}
} else {
Node *newhead = old_new[loop->_head->_idx];
set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
}
}
//------------------------------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,
CloneLoopMode mode, Node* side_by_side_idom) {
LoopNode* head = loop->_head->as_Loop();
head->verify_strip_mined(1);
if (C->do_vector_loop() && PrintOpto) { constchar* mname = C->method()->name()->as_quoted_ascii(); if (mname != NULL) {
tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
}
}
CloneMap& cm = C->clone_map(); if (C->do_vector_loop()) {
cm.set_clone_idx(cm.max_gen()+1); #ifndef PRODUCT if (PrintOpto) {
tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
loop->dump_head();
} #endif
}
// Step 1: Clone the loop body. Make the old->new mapping.
clone_loop_body(loop->_body, old_new, &cm);
// 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.
fix_body_edges(loop->_body, loop, old_new, dd, outer_loop->_parent, false);
Node_List extra_data_nodes; // data nodes in the outer strip mined loop
clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
// 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.
Node_List worklist;
uint new_counter = C->unique();
fix_ctrl_uses(loop->_body, loop, old_new, mode, side_by_side_idom, &cm, worklist);
// 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;
fix_data_uses(loop->_body, loop, mode, outer_loop, new_counter, old_new, worklist, split_if_set, split_bool_set, split_cex_set);
for (uint i = 0; i < extra_data_nodes.size(); i++) {
Node* old = extra_data_nodes.at(i);
clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
split_bool_set, split_cex_set, worklist, new_counter,
mode);
}
// 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.
finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
void PhaseIdealLoop::fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
Node* side_by_side_idom, CloneMap* cm, Node_List &worklist) {
LoopNode* head = loop->_head->as_Loop(); for(uint i = 0; i < body.size(); i++ ) {
Node* old = body.at(i); if( !old->is_CFG() ) continue;
// 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(), "" );
Node* nnn = old_new[old->_idx];
// Clone the loop exit control projection if (C->do_vector_loop() && cm != NULL) {
cm->verify_insert_and_clone(use, newuse, cm->clone_idx());
}
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 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()) { // This is not a dom_depth > dd_r because when new // control flow is constructed by a loop opt, a node and // its dominator can end up at the same dom_depth
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++; if (useuse->is_Loop() && k == LoopNode::EntryControl) { // This is not a dom_depth > dd_r because when new // control flow is constructed by a loop opt, a node // and its dominator can end up at the same dom_depth
assert(dom_depth(useuse) >= dd_r , "");
set_idom(useuse, r, dom_depth(useuse));
}
}
}
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 == NULL) ? newuse->in(0) : side_by_side_idom, dd_r);
} // End of if a loop-exit test
}
}
}
void PhaseIdealLoop::fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
IdealLoopTree* parent, bool partial) { for(uint i = 0; i < body.size(); i++ ) {
Node *old = 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, parent); if (old->outcnt() > 0) {
Node* dom = idom(old); if (old_new[dom->_idx] != NULL) {
dom = old_new[dom->_idx];
set_idom(nnn, dom, dd );
}
}
} // Correct edges to the new node for (uint j = 0; j < nnn->req(); j++) {
Node *n = nnn->in(j); if (n != NULL) {
IdealLoopTree *old_in_loop = get_loop(has_ctrl(n) ? get_ctrl(n) : n); if (loop->is_member(old_in_loop)) { if (old_new[n->_idx] != NULL) {
nnn->set_req(j, old_new[n->_idx]);
} else {
assert(!body.contains(n), "");
assert(partial, "node not cloned");
}
}
}
}
_igvn.hash_find_insert(nnn);
}
}
void PhaseIdealLoop::clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm) { for (uint i = 0; i < body.size(); i++) {
Node* old = body.at(i);
Node* nnn = old->clone();
old_new.map(old->_idx, nnn); if (old->is_reduction()) { // Reduction flag is not copied by default. Copy it here when cloning the entire loop body.
nnn->add_flag(Node::Flag_is_reduction);
} if (C->do_vector_loop() && cm != NULL) {
cm->verify_insert_and_clone(old, nnn, cm->clone_idx());
}
_igvn.register_new_node_with_optimizer(nnn);
}
}
//---------------------- 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 TypeInteger* 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, T_INT); 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, T_INT); 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, boolSigned, 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);
//------------------------------ 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) { constboolSigned = true; constboolUnsigned = 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;
ProjNode* lp_continue = lp_proj->as_Proj();
ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj(); if (!lp_exit->is_IfFalse()) { // The loop exit condition is (i <u limit) ==> (i >= 0 && i < limit). // We therefore can't add a single exit condition. return NULL;
} // The loop exit condition is !(i <u limit) ==> (i < 0 || i >= limit). // Split out the exit condition (i < 0) for stride < 0 or (i >= limit) for stride > 0.
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);
//------------------------------ 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");
VectorSet visited;
Node_Stack nstack(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)) { returntrue;
}
} returnfalse;
}
//------------------------------ 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)) { returntrue;
}
} returnfalse;
}
//------------------------------ 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);
}
}
if (C->check_node_count(worklist.size() + NodeLimitFudgeFactor, "Too many clones required in clone_for_use_outside_loop in partial peeling")) { return -1;
}
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); #ifndef 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.set(n_clone->_idx); #ifndef 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)) { returnfalse;
}
} // 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)) { returnfalse;
} // 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) { returnfalse;
}
} elseif (not_peel.test(di)) { if (peel.test(di)) { returnfalse;
}
} else { returnfalse;
}
} returntrue;
}
//------------------------------ 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
} elseif (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) { returnfalse;
}
}
}
} returntrue;
} #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 ) {
if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) { returnfalse;
}
// 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) { #ifndef PRODUCT if (TracePartialPeeling) {
tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
} #endif returnfalse;
}
}
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()) returnfalse; // 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) { returnfalse; // No peel point found
}
new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop); if (new_peel_if == NULL) { returnfalse; // 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) { returnfalse;
}
#ifndef 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
VectorSet peel;
VectorSet not_peel;
Node_List peel_list;
Node_List worklist;
Node_List sink_list;
uint estimate = loop->est_loop_clone_sz(1); if (exceeding_node_budget(estimate)) { returnfalse;
}
// 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. for (uint 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);
// 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++;
}
#ifndef PRODUCT if (TracePartialPeeling) {
tty->print_cr("\npeeled list");
} #endif
// Evacuate nodes in peel region into the not_peeled region if possible bool too_many_clones = false;
uint new_phi_cnt = 0;
uint cloned_for_outside_use = 0; for (uint i = 0; i < peel_list.size();) {
Node* n = peel_list.at(i); #ifndef 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()) { int new_clones = clone_for_use_outside_loop(loop, n, worklist); if (new_clones == -1) {
too_many_clones = true; break;
}
cloned_for_outside_use += new_clones;
sink_list.push(n);
peel.remove(n->_idx);
not_peel.set(n->_idx);
peel_list.remove(i);
incr = false; #ifndef 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 (too_many_clones || exceed_node_budget || exceed_phi_limit) { #ifndef PRODUCT if (TracePartialPeeling && exceed_phi_limit) {
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(); returntrue;
} returnfalse;
}
// 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 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");
_igvn.replace_input_of(first_not_peeled, 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);
}
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 (uint 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
// Inhibit more partial peeling on this loop
new_head_clone->set_partial_peel_loop();
C->set_major_progress();
loop->record_for_igvn();
#ifndef PRODUCT if (TracePartialPeeling) {
tty->print_cr("\nafter partial peel one iteration");
Node_List wl;
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"); elseif (tt == new_head_clone) tty->print_cr("new head"); elseif (tt == head_clone) tty->print_cr("clone head");
tt->dump();
}
} #endif returntrue;
}
// Transform: // // loop<-----------------+ // | | // stmt1 stmt2 .. stmtn | // | | | | // \ | / | // v v v | // region | // | | // shared_stmt | // | | // v | // if | // / \ | // | -----------+ // v // // into: // // loop<-------------------+ // | | // v | // +->loop | // | | | // | stmt1 stmt2 .. stmtn | // | | | | | // | | \ / | // | | v v | // | | region1 | // | | | | // | shared_stmt shared_stmt | // | | | | // | v v | // | if if | // | /\ / \ | // +-- | | -------+ // \ / // v v // region2 // // (region2 is shown to merge mirrored projections of the loop exit // ifs to make the diagram clearer but they really merge the same // projection) // // Conditions for this transformation to trigger: // - the path through stmt1 is frequent enough // - the inner loop will be turned into a counted loop after transformation bool PhaseIdealLoop::duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new) { if (!DuplicateBackedge) { returnfalse;
}
assert(!loop->_head->is_CountedLoop() || StressDuplicateBackedge, "Non-counted loop only"); if (!loop->_head->is_Loop()) { returnfalse;
}
uint estimate = loop->est_loop_clone_sz(1); if (exceeding_node_budget(estimate)) { returnfalse;
}
LoopNode *head = loop->_head->as_Loop();
Node* region = NULL;
IfNode* exit_test = NULL;
uint inner; float f; if (StressDuplicateBackedge) { if (head->is_strip_mined()) { returnfalse;
}
Node* c = head->in(LoopNode::LoopBackControl);
while (c != head) { if (c->is_Region()) {
region = c;
}
c = idom(c);
}
if (region == NULL) { returnfalse;
}
inner = 1;
} else { // Is the shape of the loop that of a counted loop...
Node* back_control = loop_exit_control(head, loop); if (back_control == NULL) { returnfalse;
}
// With an extra phi for the candidate iv? // Or the region node is the loop head if (!incr->is_Phi() || incr->in(0) == head) { returnfalse;
}
PathFrequency pf(head, this);
region = incr->in(0);
// Go over all paths for the extra phi's region and see if that // path is frequent enough and would match the expected iv shape // if the extra phi is removed
inner = 0; for (uint i = 1; i < incr->req(); ++i) {
Node* in = incr->in(i);
Node* trunc1 = NULL;
Node* trunc2 = NULL; const TypeInteger* iv_trunc_t = NULL;
Node* orig_in = in; if (!(in = CountedLoopNode::match_incr_with_optional_truncation(in, &trunc1, &trunc2, &iv_trunc_t, T_INT))) { continue;
}
assert(in->Opcode() == Op_AddI, "wrong increment code");
Node* xphi = NULL;
Node* stride = loop_iv_stride(in, loop, xphi);
f = pf.to(region->in(i)); if (f > 0.5) {
inner = i; break;
}
}
if (inner == 0) { returnfalse;
}
exit_test = back_control->in(0)->as_If();
}
if (idom(region)->is_Catch()) { returnfalse;
}
// Collect all control nodes that need to be cloned (shared_stmt in the diagram)
Unique_Node_List wq;
wq.push(head->in(LoopNode::LoopBackControl)); for (uint i = 0; i < wq.size(); i++) {
Node* c = wq.at(i);
assert(get_loop(c) == loop, "not in the right loop?"); if (c->is_Region()) { if (c != region) { for (uint j = 1; j < c->req(); ++j) {
wq.push(c->in(j));
}
}
} else {
wq.push(c->in(0));
}
assert(!is_dominator(c, region) || c == region, "shouldn't go above region");
}
Node* region_dom = idom(region);
// Can't do the transformation if this would cause a membar pair to // be split for (uint i = 0; i < wq.size(); i++) {
Node* c = wq.at(i); if (c->is_MemBar() && (c->as_MemBar()->trailing_store() || c->as_MemBar()->trailing_load_store())) {
assert(c->as_MemBar()->leading_membar()->trailing_membar() == c, "bad membar pair"); if (!wq.member(c->as_MemBar()->leading_membar())) { returnfalse;
}
}
}
// Collect data nodes that need to be clones as well int dd = dom_depth(head);
for (uint i = 0; i < loop->_body.size(); ++i) {
Node* n = loop->_body.at(i); if (has_ctrl(n)) {
Node* c = get_ctrl(n); if (wq.member(c)) {
wq.push(n);
}
} else {
set_idom(n, idom(n), dd);
}
}
// Make one of the shared_stmt copies only reachable from stmt1, the // other only from stmt2..stmtn.
Node* dom = NULL; for (uint i = 1; i < region->req(); ++i) { if (i != inner) {
_igvn.replace_input_of(region, i, C->top());
}
Node* in = region_clone->in(i); if (in->is_top()) { continue;
} if (dom == NULL) {
dom = in;
} else {
dom = dom_lca(dom, in);
}
}
set_idom(region_clone, dom, dd);
// Set up the outer loop for (uint i = 0; i < head->outcnt(); i++) {
Node* u = head->raw_out(i); if (u->is_Phi()) {
Node* outer_phi = u->clone();
outer_phi->set_req(0, outer_head);
Node* backedge = old_new[u->in(LoopNode::LoopBackControl)->_idx]; if (backedge == NULL) {
backedge = u->in(LoopNode::LoopBackControl);
}
outer_phi->set_req(LoopNode::LoopBackControl, backedge);
register_new_node(outer_phi, outer_head);
_igvn.replace_input_of(u, LoopNode::EntryControl, outer_phi);
}
}
// create control and data nodes for out of loop uses (including region2)
Node_List worklist;
uint new_counter = C->unique();
fix_ctrl_uses(wq, loop, old_new, ControlAroundStripMined, outer_head, NULL, worklist);
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