/* * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "memory/allocation.inline.hpp" #include "opto/addnode.hpp" #include "opto/connode.hpp" #include "opto/divnode.hpp" #include "opto/loopnode.hpp" #include "opto/matcher.hpp" #include "opto/mulnode.hpp" #include "opto/rootnode.hpp" #include "opto/subnode.hpp" //============================================================================= //------------------------------split_thru_phi--------------------------------- // Split Node 'n' through merge point if there is enough win. Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) { if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) { // ConvI2L may have type information on it which is unsafe to push up // so disable this for now return NULL; } int wins = 0; assert(!n->is_CFG(), ""); assert(region->is_Region(), ""); const Type* type = n->bottom_type(); const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr(); Node *phi; if (t_oop != NULL && t_oop->is_known_instance_field()) { int iid = t_oop->instance_id(); int index = C->get_alias_index(t_oop); int offset = t_oop->offset(); phi = new (C,region->req()) PhiNode(region, type, NULL, iid, index, offset); } else { phi = PhiNode::make_blank(region, n); } uint old_unique = C->unique(); for (uint i = 1; i < region->req(); i++) { Node *x; Node* the_clone = NULL; if (region->in(i) == C->top()) { x = C->top(); // Dead path? Use a dead data op } else { x = n->clone(); // Else clone up the data op the_clone = x; // Remember for possible deletion. // Alter data node to use pre-phi inputs if (n->in(0) == region) x->set_req( 0, region->in(i) ); for (uint j = 1; j < n->req(); j++) { Node *in = n->in(j); if (in->is_Phi() && in->in(0) == region) x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone } } // Check for a 'win' on some paths const Type *t = x->Value(&_igvn); bool singleton = t->singleton(); // A TOP singleton indicates that there are no possible values incoming // along a particular edge. In most cases, this is OK, and the Phi will // be eliminated later in an Ideal call. However, we can't allow this to // happen if the singleton occurs on loop entry, as the elimination of // the PhiNode may cause the resulting node to migrate back to a previous // loop iteration. if (singleton && t == Type::TOP) { // Is_Loop() == false does not confirm the absence of a loop (e.g., an // irreducible loop may not be indicated by an affirmative is_Loop()); // therefore, the only top we can split thru a phi is on a backedge of // a loop. singleton &= region->is_Loop() && (i != LoopNode::EntryControl); } if (singleton) { wins++; x = ((PhaseGVN&)_igvn).makecon(t); } else { // We now call Identity to try to simplify the cloned node. // Note that some Identity methods call phase->type(this). // Make sure that the type array is big enough for // our new node, even though we may throw the node away. // (Note: This tweaking with igvn only works because x is a new node.) _igvn.set_type(x, t); // If x is a TypeNode, capture any more-precise type permanently into Node // otherwise it will be not updated during igvn->transform since // igvn->type(x) is set to x->Value() already. x->raise_bottom_type(t); Node *y = x->Identity(&_igvn); if (y != x) { wins++; x = y; } else { y = _igvn.hash_find(x); if (y) { wins++; x = y; } else { // Else x is a new node we are keeping // We do not need register_new_node_with_optimizer // because set_type has already been called. _igvn._worklist.push(x); } } } if (x != the_clone && the_clone != NULL) _igvn.remove_dead_node(the_clone); phi->set_req( i, x ); } // Too few wins? if (wins <= policy) { _igvn.remove_dead_node(phi); return NULL; } // Record Phi register_new_node( phi, region ); for (uint i2 = 1; i2 < phi->req(); i2++) { Node *x = phi->in(i2); // If we commoned up the cloned 'x' with another existing Node, // the existing Node picks up a new use. We need to make the // existing Node occur higher up so it dominates its uses. Node *old_ctrl; IdealLoopTree *old_loop; if (x->is_Con()) { // Constant's control is always root. set_ctrl(x, C->root()); continue; } // The occasional new node if (x->_idx >= old_unique) { // Found a new, unplaced node? old_ctrl = NULL; old_loop = NULL; // Not in any prior loop } else { old_ctrl = get_ctrl(x); old_loop = get_loop(old_ctrl); // Get prior loop } // New late point must dominate new use Node *new_ctrl = dom_lca(old_ctrl, region->in(i2)); if (new_ctrl == old_ctrl) // Nothing is changed continue; IdealLoopTree *new_loop = get_loop(new_ctrl); // Don't move x into a loop if its uses are // outside of loop. Otherwise x will be cloned // for each use outside of this loop. IdealLoopTree *use_loop = get_loop(region); if (!new_loop->is_member(use_loop) && (old_loop == NULL || !new_loop->is_member(old_loop))) { // Take early control, later control will be recalculated // during next iteration of loop optimizations. new_ctrl = get_early_ctrl(x); new_loop = get_loop(new_ctrl); } // Set new location set_ctrl(x, new_ctrl); // If changing loop bodies, see if we need to collect into new body if (old_loop != new_loop) { if (old_loop && !old_loop->_child) old_loop->_body.yank(x); if (!new_loop->_child) new_loop->_body.push(x); // Collect body info } } return phi; } //------------------------------dominated_by------------------------------------ // Replace the dominated test with an obvious true or false. Place it on the // IGVN worklist for later cleanup. Move control-dependent data Nodes on the // live path up to the dominating control. void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) { #ifndef PRODUCT if (VerifyLoopOptimizations && PrintOpto) tty->print_cr("dominating test"); #endif // prevdom is the dominating projection of the dominating test. assert( iff->is_If(), "" ); assert( iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added"); int pop = prevdom->Opcode(); assert( pop == Op_IfFalse || pop == Op_IfTrue, "" ); if (flip) { if (pop == Op_IfTrue) pop = Op_IfFalse; else pop = Op_IfTrue; } // 'con' is set to true or false to kill the dominated test. Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO); set_ctrl(con, C->root()); // Constant gets a new use // Hack the dominated test _igvn.hash_delete(iff); iff->set_req(1, con); _igvn._worklist.push(iff); // If I dont have a reachable TRUE and FALSE path following the IfNode then // I can assume this path reaches an infinite loop. In this case it's not // important to optimize the data Nodes - either the whole compilation will // be tossed or this path (and all data Nodes) will go dead. if (iff->outcnt() != 2) return; // Make control-dependent data Nodes on the live path (path that will remain // once the dominated IF is removed) become control-dependent on the // dominating projection. Node* dp = iff->as_If()->proj_out(pop == Op_IfTrue); // Loop predicates may have depending checks which should not // be skipped. For example, range check predicate has two checks // for lower and upper bounds. ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp->as_Proj()->_con)->as_Proj(); if (exclude_loop_predicate && is_uncommon_trap_proj(unc_proj, Deoptimization::Reason_predicate)) return; // Let IGVN transformation change control dependence. IdealLoopTree *old_loop = get_loop(dp); for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) { Node* cd = dp->fast_out(i); // Control-dependent node if (cd->depends_only_on_test()) { assert(cd->in(0) == dp, ""); _igvn.hash_delete(cd); cd->set_req(0, prevdom); set_early_ctrl(cd); _igvn._worklist.push(cd); IdealLoopTree *new_loop = get_loop(get_ctrl(cd)); if (old_loop != new_loop) { if (!old_loop->_child) old_loop->_body.yank(cd); if (!new_loop->_child) new_loop->_body.push(cd); } --i; --imax; } } } //------------------------------has_local_phi_input---------------------------- // Return TRUE if 'n' has Phi inputs from its local block and no other // block-local inputs (all non-local-phi inputs come from earlier blocks) Node *PhaseIdealLoop::has_local_phi_input( Node *n ) { Node *n_ctrl = get_ctrl(n); // See if some inputs come from a Phi in this block, or from before // this block. uint i; for( i = 1; i < n->req(); i++ ) { Node *phi = n->in(i); if( phi->is_Phi() && phi->in(0) == n_ctrl ) break; } if( i >= n->req() ) return NULL; // No Phi inputs; nowhere to clone thru // Check for inputs created between 'n' and the Phi input. These // must split as well; they have already been given the chance // (courtesy of a post-order visit) and since they did not we must // recover the 'cost' of splitting them by being very profitable // when splitting 'n'. Since this is unlikely we simply give up. for( i = 1; i < n->req(); i++ ) { Node *m = n->in(i); if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) { // We allow the special case of AddP's with no local inputs. // This allows us to split-up address expressions. if (m->is_AddP() && get_ctrl(m->in(2)) != n_ctrl && get_ctrl(m->in(3)) != n_ctrl) { // Move the AddP up to dominating point set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl))); continue; } return NULL; } } return n_ctrl; } //------------------------------remix_address_expressions---------------------- // Rework addressing expressions to get the most loop-invariant stuff // moved out. We'd like to do all associative operators, but it's especially // important (common) to do address expressions. Node *PhaseIdealLoop::remix_address_expressions( Node *n ) { if (!has_ctrl(n)) return NULL; Node *n_ctrl = get_ctrl(n); IdealLoopTree *n_loop = get_loop(n_ctrl); // See if 'n' mixes loop-varying and loop-invariant inputs and // itself is loop-varying. // Only interested in binary ops (and AddP) if( n->req() < 3 || n->req() > 4 ) return NULL; Node *n1_ctrl = get_ctrl(n->in( 1)); Node *n2_ctrl = get_ctrl(n->in( 2)); Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3)); IdealLoopTree *n1_loop = get_loop( n1_ctrl ); IdealLoopTree *n2_loop = get_loop( n2_ctrl ); IdealLoopTree *n3_loop = get_loop( n3_ctrl ); // Does one of my inputs spin in a tighter loop than self? if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) || (n_loop->is_member( n2_loop ) && n_loop != n2_loop) || (n_loop->is_member( n3_loop ) && n_loop != n3_loop) ) return NULL; // Leave well enough alone // Is at least one of my inputs loop-invariant? if( n1_loop == n_loop && n2_loop == n_loop && n3_loop == n_loop ) return NULL; // No loop-invariant inputs int n_op = n->Opcode(); // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2). if( n_op == Op_LShiftI ) { // Scale is loop invariant Node *scale = n->in(2); Node *scale_ctrl = get_ctrl(scale); IdealLoopTree *scale_loop = get_loop(scale_ctrl ); if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) ) return NULL; const TypeInt *scale_t = scale->bottom_type()->isa_int(); if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 ) return NULL; // Dont bother with byte/short masking // Add must vary with loop (else shift would be loop-invariant) Node *add = n->in(1); Node *add_ctrl = get_ctrl(add); IdealLoopTree *add_loop = get_loop(add_ctrl); //assert( n_loop == add_loop, "" ); if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops // Convert I-V into I+ (0-V); same for V-I if( add->Opcode() == Op_SubI && _igvn.type( add->in(1) ) != TypeInt::ZERO ) { Node *zero = _igvn.intcon(0); set_ctrl(zero, C->root()); Node *neg = new (C, 3) SubINode( _igvn.intcon(0), add->in(2) ); register_new_node( neg, get_ctrl(add->in(2) ) ); add = new (C, 3) AddINode( add->in(1), neg ); register_new_node( add, add_ctrl ); } if( add->Opcode() != Op_AddI ) return NULL; // See if one add input is loop invariant Node *add_var = add->in(1); Node *add_var_ctrl = get_ctrl(add_var); IdealLoopTree *add_var_loop = get_loop(add_var_ctrl ); Node *add_invar = add->in(2); Node *add_invar_ctrl = get_ctrl(add_invar); IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl ); if( add_var_loop == n_loop ) { } else if( add_invar_loop == n_loop ) { // Swap to find the invariant part add_invar = add_var; add_invar_ctrl = add_var_ctrl; add_invar_loop = add_var_loop; add_var = add->in(2); Node *add_var_ctrl = get_ctrl(add_var); IdealLoopTree *add_var_loop = get_loop(add_var_ctrl ); } else // Else neither input is loop invariant return NULL; if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) ) return NULL; // No invariant part of the add? // Yes! Reshape address expression! Node *inv_scale = new (C, 3) LShiftINode( add_invar, scale ); Node *inv_scale_ctrl = dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ? add_invar_ctrl : scale_ctrl; register_new_node( inv_scale, inv_scale_ctrl ); Node *var_scale = new (C, 3) LShiftINode( add_var, scale ); register_new_node( var_scale, n_ctrl ); Node *var_add = new (C, 3) AddINode( var_scale, inv_scale ); register_new_node( var_add, n_ctrl ); _igvn.replace_node( n, var_add ); return var_add; } // Replace (I+V) with (V+I) if( n_op == Op_AddI || n_op == Op_AddL || n_op == Op_AddF || n_op == Op_AddD || n_op == Op_MulI || n_op == Op_MulL || n_op == Op_MulF || n_op == Op_MulD ) { if( n2_loop == n_loop ) { assert( n1_loop != n_loop, "" ); n->swap_edges(1, 2); } } // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V), // but not if I2 is a constant. if( n_op == Op_AddP ) { if( n2_loop == n_loop && n3_loop != n_loop ) { if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) { Node *n22_ctrl = get_ctrl(n->in(2)->in(2)); Node *n23_ctrl = get_ctrl(n->in(2)->in(3)); IdealLoopTree *n22loop = get_loop( n22_ctrl ); IdealLoopTree *n23_loop = get_loop( n23_ctrl ); if( n22loop != n_loop && n22loop->is_member(n_loop) && n23_loop == n_loop ) { Node *add1 = new (C, 4) AddPNode( n->in(1), n->in(2)->in(2), n->in(3) ); // Stuff new AddP in the loop preheader register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) ); Node *add2 = new (C, 4) AddPNode( n->in(1), add1, n->in(2)->in(3) ); register_new_node( add2, n_ctrl ); _igvn.replace_node( n, add2 ); return add2; } } } // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V) if( n2_loop != n_loop && n3_loop == n_loop ) { if( n->in(3)->Opcode() == Op_AddI ) { Node *V = n->in(3)->in(1); Node *I = n->in(3)->in(2); if( is_member(n_loop,get_ctrl(V)) ) { } else { Node *tmp = V; V = I; I = tmp; } if( !is_member(n_loop,get_ctrl(I)) ) { Node *add1 = new (C, 4) AddPNode( n->in(1), n->in(2), I ); // Stuff new AddP in the loop preheader register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) ); Node *add2 = new (C, 4) AddPNode( n->in(1), add1, V ); register_new_node( add2, n_ctrl ); _igvn.replace_node( n, add2 ); return add2; } } } } return NULL; } //------------------------------conditional_move------------------------------- // Attempt to replace a Phi with a conditional move. We have some pretty // strict profitability requirements. All Phis at the merge point must // be converted, so we can remove the control flow. We need to limit the // number of c-moves to a small handful. All code that was in the side-arms // of the CFG diamond is now speculatively executed. This code has to be // "cheap enough". We are pretty much limited to CFG diamonds that merge // 1 or 2 items with a total of 1 or 2 ops executed speculatively. Node *PhaseIdealLoop::conditional_move( Node *region ) { assert(region->is_Region(), "sanity check"); if (region->req() != 3) return NULL; // Check for CFG diamond Node *lp = region->in(1); Node *rp = region->in(2); if (!lp || !rp) return NULL; Node *lp_c = lp->in(0); if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL; IfNode *iff = lp_c->as_If(); // Check for ops pinned in an arm of the diamond. // Can't remove the control flow in this case if (lp->outcnt() > 1) return NULL; if (rp->outcnt() > 1) return NULL; IdealLoopTree* r_loop = get_loop(region); assert(r_loop == get_loop(iff), "sanity"); // Always convert to CMOVE if all results are used only outside this loop. bool used_inside_loop = (r_loop == _ltree_root); // Check profitability int cost = 0; int phis = 0; for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { Node *out = region->fast_out(i); if (!out->is_Phi()) continue; // Ignore other control edges, etc phis++; PhiNode* phi = out->as_Phi(); BasicType bt = phi->type()->basic_type(); switch (bt) { case T_FLOAT: case T_DOUBLE: { cost += Matcher::float_cmove_cost(); // Could be very expensive break; } case T_LONG: { cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's } case T_INT: // These all CMOV fine case T_ADDRESS: { // (RawPtr) cost++; break; } case T_NARROWOOP: // Fall through case T_OBJECT: { // Base oops are OK, but not derived oops const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr(); // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus // CMOVE'ing a derived pointer requires we also CMOVE the base. If we // have a Phi for the base here that we convert to a CMOVE all is well // and good. But if the base is dead, we'll not make a CMOVE. Later // the allocator will have to produce a base by creating a CMOVE of the // relevant bases. This puts the allocator in the business of // manufacturing expensive instructions, generally a bad plan. // Just Say No to Conditionally-Moved Derived Pointers. if (tp && tp->offset() != 0) return NULL; cost++; break; } default: return NULL; // In particular, can't do memory or I/O } // Add in cost any speculative ops for (uint j = 1; j < region->req(); j++) { Node *proj = region->in(j); Node *inp = phi->in(j); if (get_ctrl(inp) == proj) { // Found local op cost++; // Check for a chain of dependent ops; these will all become // speculative in a CMOV. for (uint k = 1; k < inp->req(); k++) if (get_ctrl(inp->in(k)) == proj) cost += ConditionalMoveLimit; // Too much speculative goo } } // See if the Phi is used by a Cmp or Narrow oop Decode/Encode. // This will likely Split-If, a higher-payoff operation. for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) { Node* use = phi->fast_out(k); if (use->is_Cmp() || use->is_DecodeN() || use->is_EncodeP()) cost += ConditionalMoveLimit; // Is there a use inside the loop? // Note: check only basic types since CMoveP is pinned. if (!used_inside_loop && is_java_primitive(bt)) { IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use); if (r_loop == u_loop || r_loop->is_member(u_loop)) { used_inside_loop = true; } } } } Node* bol = iff->in(1); assert(bol->Opcode() == Op_Bool, ""); int cmp_op = bol->in(1)->Opcode(); // It is expensive to generate flags from a float compare. // Avoid duplicated float compare. if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL; float infrequent_prob = PROB_UNLIKELY_MAG(3); // Ignore cost and blocks frequency if CMOVE can be moved outside the loop. if (used_inside_loop) { if (cost >= ConditionalMoveLimit) return NULL; // Too much goo // BlockLayoutByFrequency optimization moves infrequent branch // from hot path. No point in CMOV'ing in such case (110 is used // instead of 100 to take into account not exactness of float value). if (BlockLayoutByFrequency) { infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f); } } // Check for highly predictable branch. No point in CMOV'ing if // we are going to predict accurately all the time. if (iff->_prob < infrequent_prob || iff->_prob > (1.0f - infrequent_prob)) return NULL; // -------------- // Now replace all Phis with CMOV's Node *cmov_ctrl = iff->in(0); uint flip = (lp->Opcode() == Op_IfTrue); while (1) { PhiNode* phi = NULL; for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { Node *out = region->fast_out(i); if (out->is_Phi()) { phi = out->as_Phi(); break; } } if (phi == NULL) break; #ifndef PRODUCT if (PrintOpto && VerifyLoopOptimizations) tty->print_cr("CMOV"); #endif // Move speculative ops for (uint j = 1; j < region->req(); j++) { Node *proj = region->in(j); Node *inp = phi->in(j); if (get_ctrl(inp) == proj) { // Found local op #ifndef PRODUCT if (PrintOpto && VerifyLoopOptimizations) { tty->print(" speculate: "); inp->dump(); } #endif set_ctrl(inp, cmov_ctrl); } } Node *cmov = CMoveNode::make( C, cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi) ); register_new_node( cmov, cmov_ctrl ); _igvn.replace_node( phi, cmov ); #ifndef PRODUCT if (TraceLoopOpts) { tty->print("CMOV "); r_loop->dump_head(); if (Verbose) { bol->in(1)->dump(1); cmov->dump(1); } } if (VerifyLoopOptimizations) verify(); #endif } // The useless CFG diamond will fold up later; see the optimization in // RegionNode::Ideal. _igvn._worklist.push(region); return iff->in(1); } //------------------------------split_if_with_blocks_pre----------------------- // Do the real work in a non-recursive function. Data nodes want to be // cloned in the pre-order so they can feed each other nicely. Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) { // Cloning these guys is unlikely to win int n_op = n->Opcode(); if( n_op == Op_MergeMem ) return n; if( n->is_Proj() ) return n; // Do not clone-up CmpFXXX variations, as these are always // followed by a CmpI if( n->is_Cmp() ) return n; // Attempt to use a conditional move instead of a phi/branch if( ConditionalMoveLimit > 0 && n_op == Op_Region ) { Node *cmov = conditional_move( n ); if( cmov ) return cmov; } if( n->is_CFG() || n->is_LoadStore() ) return n; if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd n_op == Op_Opaque2 ) { if( !C->major_progress() ) // If chance of no more loop opts... _igvn._worklist.push(n); // maybe we'll remove them return n; } if( n->is_Con() ) return n; // No cloning for Con nodes Node *n_ctrl = get_ctrl(n); if( !n_ctrl ) return n; // Dead node // Attempt to remix address expressions for loop invariants Node *m = remix_address_expressions( n ); if( m ) return m; // Determine if the Node has inputs from some local Phi. // Returns the block to clone thru. Node *n_blk = has_local_phi_input( n ); if( !n_blk ) return n; // Do not clone the trip counter through on a CountedLoop // (messes up the canonical shape). if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n; // Check for having no control input; not pinned. Allow // dominating control. if( n->in(0) ) { Node *dom = idom(n_blk); if( dom_lca( n->in(0), dom ) != n->in(0) ) return n; } // Policy: when is it profitable. You must get more wins than // policy before it is considered profitable. Policy is usually 0, // so 1 win is considered profitable. Big merges will require big // cloning, so get a larger policy. int policy = n_blk->req() >> 2; // If the loop is a candidate for range check elimination, // delay splitting through it's phi until a later loop optimization if (n_blk->is_CountedLoop()) { IdealLoopTree *lp = get_loop(n_blk); if (lp && lp->_rce_candidate) { return n; } } // Use same limit as split_if_with_blocks_post if( C->unique() > 35000 ) return n; // Method too big // Split 'n' through the merge point if it is profitable Node *phi = split_thru_phi( n, n_blk, policy ); if (!phi) return n; // Found a Phi to split thru! // Replace 'n' with the new phi _igvn.replace_node( n, phi ); // Moved a load around the loop, 'en-registering' something. if (n_blk->is_Loop() && n->is_Load() && !phi->in(LoopNode::LoopBackControl)->is_Load()) C->set_major_progress(); return phi; } static bool merge_point_too_heavy(Compile* C, Node* region) { // Bail out if the region and its phis have too many users. int weight = 0; for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { weight += region->fast_out(i)->outcnt(); } int nodes_left = MaxNodeLimit - C->unique(); if (weight * 8 > nodes_left) { #ifndef PRODUCT if (PrintOpto) tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight); #endif return true; } else { return false; } } static bool merge_point_safe(Node* region) { // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode // having a PhiNode input. This sidesteps the dangerous case where the split // ConvI2LNode may become TOP if the input Value() does not // overlap the ConvI2L range, leaving a node which may not dominate its // uses. // A better fix for this problem can be found in the BugTraq entry, but // expediency for Mantis demands this hack. // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop // split_if_with_blocks from splitting a block because we could not move around // the FastLockNode. for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { Node* n = region->fast_out(i); if (n->is_Phi()) { for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) { Node* m = n->fast_out(j); if (m->is_FastLock()) return false; #ifdef _LP64 if (m->Opcode() == Op_ConvI2L) return false; #endif } } } return true; } //------------------------------place_near_use--------------------------------- // Place some computation next to use but not inside inner loops. // For inner loop uses move it to the preheader area. Node *PhaseIdealLoop::place_near_use( Node *useblock ) const { IdealLoopTree *u_loop = get_loop( useblock ); return (u_loop->_irreducible || u_loop->_child) ? useblock : u_loop->_head->in(LoopNode::EntryControl); } //------------------------------split_if_with_blocks_post---------------------- // Do the real work in a non-recursive function. CFG hackery wants to be // in the post-order, so it can dirty the I-DOM info and not use the dirtied // info. void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) { // Cloning Cmp through Phi's involves the split-if transform. // FastLock is not used by an If if( n->is_Cmp() && !n->is_FastLock() ) { if( C->unique() > 35000 ) return; // Method too big // Do not do 'split-if' if irreducible loops are present. if( _has_irreducible_loops ) return; Node *n_ctrl = get_ctrl(n); // Determine if the Node has inputs from some local Phi. // Returns the block to clone thru. Node *n_blk = has_local_phi_input( n ); if( n_blk != n_ctrl ) return; if( merge_point_too_heavy(C, n_ctrl) ) return; if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare? Node *bol = n->unique_out(); assert( bol->is_Bool(), "expect a bool here" ); if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare? Node *iff = bol->unique_out(); // Check some safety conditions if( iff->is_If() ) { // Classic split-if? if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if } else if (iff->is_CMove()) { // Trying to split-up a CMOVE if( get_ctrl(iff->in(2)) == n_ctrl || get_ctrl(iff->in(3)) == n_ctrl ) return; // Inputs not yet split-up if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) { return; // Loop-invar test gates loop-varying CMOVE } } else { return; // some other kind of node, such as an Allocate } // Do not do 'split-if' if some paths are dead. First do dead code // elimination and then see if its still profitable. for( uint i = 1; i < n_ctrl->req(); i++ ) if( n_ctrl->in(i) == C->top() ) return; // When is split-if profitable? Every 'win' on means some control flow // goes dead, so it's almost always a win. int policy = 0; // If trying to do a 'Split-If' at the loop head, it is only // profitable if the cmp folds up on BOTH paths. Otherwise we // risk peeling a loop forever. // CNC - Disabled for now. Requires careful handling of loop // body selection for the cloned code. Also, make sure we check // for any input path not being in the same loop as n_ctrl. For // irreducible loops we cannot check for 'n_ctrl->is_Loop()' // because the alternative loop entry points won't be converted // into LoopNodes. IdealLoopTree *n_loop = get_loop(n_ctrl); for( uint j = 1; j < n_ctrl->req(); j++ ) if( get_loop(n_ctrl->in(j)) != n_loop ) return; // Check for safety of the merge point. if( !merge_point_safe(n_ctrl) ) { return; } // Split compare 'n' through the merge point if it is profitable Node *phi = split_thru_phi( n, n_ctrl, policy ); if( !phi ) return; // Found a Phi to split thru! // Replace 'n' with the new phi _igvn.replace_node( n, phi ); // Now split the bool up thru the phi Node *bolphi = split_thru_phi( bol, n_ctrl, -1 ); _igvn.replace_node( bol, bolphi ); assert( iff->in(1) == bolphi, "" ); if( bolphi->Value(&_igvn)->singleton() ) return; // Conditional-move? Must split up now if( !iff->is_If() ) { Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 ); _igvn.replace_node( iff, cmovphi ); return; } // Now split the IF do_split_if( iff ); return; } // Check for an IF ready to split; one that has its // condition codes input coming from a Phi at the block start. int n_op = n->Opcode(); // Check for an IF being dominated by another IF same test if( n_op == Op_If ) { Node *bol = n->in(1); uint max = bol->outcnt(); // Check for same test used more than once? if( n_op == Op_If && max > 1 && bol->is_Bool() ) { // Search up IDOMs to see if this IF is dominated. Node *cutoff = get_ctrl(bol); // Now search up IDOMs till cutoff, looking for a dominating test Node *prevdom = n; Node *dom = idom(prevdom); while( dom != cutoff ) { if( dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom ) { // Replace the dominated test with an obvious true or false. // Place it on the IGVN worklist for later cleanup. C->set_major_progress(); dominated_by( prevdom, n, false, true ); #ifndef PRODUCT if( VerifyLoopOptimizations ) verify(); #endif return; } prevdom = dom; dom = idom(prevdom); } } } // See if a shared loop-varying computation has no loop-varying uses. // Happens if something is only used for JVM state in uncommon trap exits, // like various versions of induction variable+offset. Clone the // computation per usage to allow it to sink out of the loop. if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about) Node *n_ctrl = get_ctrl(n); IdealLoopTree *n_loop = get_loop(n_ctrl); if( n_loop != _ltree_root ) { DUIterator_Fast imax, i = n->fast_outs(imax); for (; i < imax; i++) { Node* u = n->fast_out(i); if( !has_ctrl(u) ) break; // Found control user IdealLoopTree *u_loop = get_loop(get_ctrl(u)); if( u_loop == n_loop ) break; // Found loop-varying use if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003 } bool did_break = (i < imax); // Did we break out of the previous loop? if (!did_break && n->outcnt() > 1) { // All uses in outer loops! Node *late_load_ctrl; if (n->is_Load()) { // If n is a load, get and save the result from get_late_ctrl(), // to be later used in calculating the control for n's clones. clear_dom_lca_tags(); late_load_ctrl = get_late_ctrl(n, n_ctrl); } // If n is a load, and the late control is the same as the current // control, then the cloning of n is a pointless exercise, because // GVN will ensure that we end up where we started. if (!n->is_Load() || late_load_ctrl != n_ctrl) { for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) { Node *u = n->last_out(j); // Clone private computation per use _igvn.hash_delete(u); _igvn._worklist.push(u); Node *x = n->clone(); // Clone computation Node *x_ctrl = NULL; if( u->is_Phi() ) { // Replace all uses of normal nodes. Replace Phi uses // individually, so the separate Nodes can sink down // different paths. uint k = 1; while( u->in(k) != n ) k++; u->set_req( k, x ); // x goes next to Phi input path x_ctrl = u->in(0)->in(k); --j; } else { // Normal use // Replace all uses for( uint k = 0; k < u->req(); k++ ) { if( u->in(k) == n ) { u->set_req( k, x ); --j; } } x_ctrl = get_ctrl(u); } // Find control for 'x' next to use but not inside inner loops. // For inner loop uses get the preheader area. x_ctrl = place_near_use(x_ctrl); if (n->is_Load()) { // For loads, add a control edge to a CFG node outside of the loop // to force them to not combine and return back inside the loop // during GVN optimization (4641526). // // Because we are setting the actual control input, factor in // the result from get_late_ctrl() so we respect any // anti-dependences. (6233005). x_ctrl = dom_lca(late_load_ctrl, x_ctrl); // Don't allow the control input to be a CFG splitting node. // Such nodes should only have ProjNodes as outs, e.g. IfNode // should only have IfTrueNode and IfFalseNode (4985384). x_ctrl = find_non_split_ctrl(x_ctrl); assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone"); x->set_req(0, x_ctrl); } register_new_node(x, x_ctrl); // Some institutional knowledge is needed here: 'x' is // yanked because if the optimizer runs GVN on it all the // cloned x's will common up and undo this optimization and // be forced back in the loop. This is annoying because it // makes +VerifyOpto report false-positives on progress. I // tried setting control edges on the x's to force them to // not combine, but the matching gets worried when it tries // to fold a StoreP and an AddP together (as part of an // address expression) and the AddP and StoreP have // different controls. if( !x->is_Load() && !x->is_DecodeN() ) _igvn._worklist.yank(x); } _igvn.remove_dead_node(n); } } } } // Check for Opaque2's who's loop has disappeared - who's input is in the // same loop nest as their output. Remove 'em, they are no longer useful. if( n_op == Op_Opaque2 && n->in(1) != NULL && get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) { _igvn.replace_node( n, n->in(1) ); } } //------------------------------split_if_with_blocks--------------------------- // Check for aggressive application of 'split-if' optimization, // using basic block level info. void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) { Node *n = C->root(); visited.set(n->_idx); // first, mark node as visited // Do pre-visit work for root n = split_if_with_blocks_pre( n ); uint cnt = n->outcnt(); uint i = 0; while (true) { // Visit all children if (i < cnt) { Node* use = n->raw_out(i); ++i; if (use->outcnt() != 0 && !visited.test_set(use->_idx)) { // Now do pre-visit work for this use use = split_if_with_blocks_pre( use ); nstack.push(n, i); // Save parent and next use's index. n = use; // Process all children of current use. cnt = use->outcnt(); i = 0; } } else { // All of n's children have been processed, complete post-processing. if (cnt != 0 && !n->is_Con()) { assert(has_node(n), "no dead nodes"); split_if_with_blocks_post( n ); } if (nstack.is_empty()) { // Finished all nodes on stack. break; } // Get saved parent node and next use's index. Visit the rest of uses. n = nstack.node(); cnt = n->outcnt(); i = nstack.index(); nstack.pop(); } } } //============================================================================= // // C L O N E A L O O P B O D Y // //------------------------------clone_iff-------------------------------------- // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps. // "Nearly" because all Nodes have been cloned from the original in the loop, // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs // through the Phi recursively, and return a Bool. BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) { // Convert this Phi into a Phi merging Bools uint i; for( i = 1; i < phi->req(); i++ ) { Node *b = phi->in(i); if( b->is_Phi() ) { _igvn.hash_delete(phi); _igvn._worklist.push(phi); phi->set_req(i, clone_iff( b->as_Phi(), loop )); } else { assert( b->is_Bool(), "" ); } } Node *sample_bool = phi->in(1); Node *sample_cmp = sample_bool->in(1); // Make Phis to merge the Cmp's inputs. int size = phi->in(0)->req(); PhiNode *phi1 = new (C, size) PhiNode( phi->in(0), Type::TOP ); PhiNode *phi2 = new (C, size) PhiNode( phi->in(0), Type::TOP ); for( i = 1; i < phi->req(); i++ ) { Node *n1 = phi->in(i)->in(1)->in(1); Node *n2 = phi->in(i)->in(1)->in(2); phi1->set_req( i, n1 ); phi2->set_req( i, n2 ); phi1->set_type( phi1->type()->meet(n1->bottom_type()) ); phi2->set_type( phi2->type()->meet(n2->bottom_type()) ); } // See if these Phis have been made before. // Register with optimizer Node *hit1 = _igvn.hash_find_insert(phi1); if( hit1 ) { // Hit, toss just made Phi _igvn.remove_dead_node(phi1); // Remove new phi assert( hit1->is_Phi(), "" ); phi1 = (PhiNode*)hit1; // Use existing phi } else { // Miss _igvn.register_new_node_with_optimizer(phi1); } Node *hit2 = _igvn.hash_find_insert(phi2); if( hit2 ) { // Hit, toss just made Phi _igvn.remove_dead_node(phi2); // Remove new phi assert( hit2->is_Phi(), "" ); phi2 = (PhiNode*)hit2; // Use existing phi } else { // Miss _igvn.register_new_node_with_optimizer(phi2); } // Register Phis with loop/block info set_ctrl(phi1, phi->in(0)); set_ctrl(phi2, phi->in(0)); // Make a new Cmp Node *cmp = sample_cmp->clone(); cmp->set_req( 1, phi1 ); cmp->set_req( 2, phi2 ); _igvn.register_new_node_with_optimizer(cmp); set_ctrl(cmp, phi->in(0)); // Make a new Bool Node *b = sample_bool->clone(); b->set_req(1,cmp); _igvn.register_new_node_with_optimizer(b); set_ctrl(b, phi->in(0)); assert( b->is_Bool(), "" ); return (BoolNode*)b; } //------------------------------clone_bool------------------------------------- // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps. // "Nearly" because all Nodes have been cloned from the original in the loop, // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs // through the Phi recursively, and return a Bool. CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) { uint i; // Convert this Phi into a Phi merging Bools for( i = 1; i < phi->req(); i++ ) { Node *b = phi->in(i); if( b->is_Phi() ) { _igvn.hash_delete(phi); _igvn._worklist.push(phi); phi->set_req(i, clone_bool( b->as_Phi(), loop )); } else { assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" ); } } Node *sample_cmp = phi->in(1); // Make Phis to merge the Cmp's inputs. int size = phi->in(0)->req(); PhiNode *phi1 = new (C, size) PhiNode( phi->in(0), Type::TOP ); PhiNode *phi2 = new (C, size) PhiNode( phi->in(0), Type::TOP ); for( uint j = 1; j < phi->req(); j++ ) { Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP Node *n1, *n2; if( cmp_top->is_Cmp() ) { n1 = cmp_top->in(1); n2 = cmp_top->in(2); } else { n1 = n2 = cmp_top; } phi1->set_req( j, n1 ); phi2->set_req( j, n2 ); phi1->set_type( phi1->type()->meet(n1->bottom_type()) ); phi2->set_type( phi2->type()->meet(n2->bottom_type()) ); } // See if these Phis have been made before. // Register with optimizer Node *hit1 = _igvn.hash_find_insert(phi1); if( hit1 ) { // Hit, toss just made Phi _igvn.remove_dead_node(phi1); // Remove new phi assert( hit1->is_Phi(), "" ); phi1 = (PhiNode*)hit1; // Use existing phi } else { // Miss _igvn.register_new_node_with_optimizer(phi1); } Node *hit2 = _igvn.hash_find_insert(phi2); if( hit2 ) { // Hit, toss just made Phi _igvn.remove_dead_node(phi2); // Remove new phi assert( hit2->is_Phi(), "" ); phi2 = (PhiNode*)hit2; // Use existing phi } else { // Miss _igvn.register_new_node_with_optimizer(phi2); } // Register Phis with loop/block info set_ctrl(phi1, phi->in(0)); set_ctrl(phi2, phi->in(0)); // Make a new Cmp Node *cmp = sample_cmp->clone(); cmp->set_req( 1, phi1 ); cmp->set_req( 2, phi2 ); _igvn.register_new_node_with_optimizer(cmp); set_ctrl(cmp, phi->in(0)); assert( cmp->is_Cmp(), "" ); return (CmpNode*)cmp; } //------------------------------sink_use--------------------------------------- // If 'use' was in the loop-exit block, it now needs to be sunk // below the post-loop merge point. void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) { if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) { set_ctrl(use, post_loop); for (DUIterator j = use->outs(); use->has_out(j); j++) sink_use(use->out(j), post_loop); } } //------------------------------clone_loop------------------------------------- // // C L O N E A L O O P B O D Y // // This is the basic building block of the loop optimizations. It clones an // entire loop body. It makes an old_new loop body mapping; with this mapping // you can find the new-loop equivalent to an old-loop node. All new-loop // nodes are exactly equal to their old-loop counterparts, all edges are the // same. All exits from the old-loop now have a RegionNode that merges the // equivalent new-loop path. This is true even for the normal "loop-exit" // condition. All uses of loop-invariant old-loop values now come from (one // or more) Phis that merge their new-loop equivalents. // // This operation leaves the graph in an illegal state: there are two valid // control edges coming from the loop pre-header to both loop bodies. I'll // definitely have to hack the graph after running this transform. // // From this building block I will further edit edges to perform loop peeling // or loop unrolling or iteration splitting (Range-Check-Elimination), etc. // // Parameter side_by_size_idom: // When side_by_size_idom is NULL, the dominator tree is constructed for // the clone loop to dominate the original. Used in construction of // pre-main-post loop sequence. // When nonnull, the clone and original are side-by-side, both are // dominated by the side_by_side_idom node. Used in construction of // unswitched loops. void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd, Node* side_by_side_idom) { // Step 1: Clone the loop body. Make the old->new mapping. uint i; for( i = 0; i < loop->_body.size(); i++ ) { Node *old = loop->_body.at(i); Node *nnn = old->clone(); old_new.map( old->_idx, nnn ); _igvn.register_new_node_with_optimizer(nnn); } // Step 2: Fix the edges in the new body. If the old input is outside the // loop use it. If the old input is INside the loop, use the corresponding // new node instead. for( i = 0; i < loop->_body.size(); i++ ) { Node *old = loop->_body.at(i); Node *nnn = old_new[old->_idx]; // Fix CFG/Loop controlling the new node if (has_ctrl(old)) { set_ctrl(nnn, old_new[get_ctrl(old)->_idx]); } else { set_loop(nnn, loop->_parent); if (old->outcnt() > 0) { set_idom( nnn, old_new[idom(old)->_idx], dd ); } } // Correct edges to the new node for( uint j = 0; j < nnn->req(); j++ ) { Node *n = nnn->in(j); if( n ) { IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n ); if( loop->is_member( old_in_loop ) ) nnn->set_req(j, old_new[n->_idx]); } } _igvn.hash_find_insert(nnn); } Node *newhead = old_new[loop->_head->_idx]; set_idom(newhead, newhead->in(LoopNode::EntryControl), dd); // Step 3: Now fix control uses. Loop varying control uses have already // been fixed up (as part of all input edges in Step 2). Loop invariant // control uses must be either an IfFalse or an IfTrue. Make a merge // point to merge the old and new IfFalse/IfTrue nodes; make the use // refer to this. ResourceArea *area = Thread::current()->resource_area(); Node_List worklist(area); uint new_counter = C->unique(); for( i = 0; i < loop->_body.size(); i++ ) { Node* old = loop->_body.at(i); if( !old->is_CFG() ) continue; Node* nnn = old_new[old->_idx]; // Copy uses to a worklist, so I can munge the def-use info // with impunity. for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++) worklist.push(old->fast_out(j)); while( worklist.size() ) { // Visit all uses Node *use = worklist.pop(); if (!has_node(use)) continue; // Ignore dead nodes IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use ); if( !loop->is_member( use_loop ) && use->is_CFG() ) { // Both OLD and USE are CFG nodes here. assert( use->is_Proj(), "" ); // Clone the loop exit control projection Node *newuse = use->clone(); newuse->set_req(0,nnn); _igvn.register_new_node_with_optimizer(newuse); set_loop(newuse, use_loop); set_idom(newuse, nnn, dom_depth(nnn) + 1 ); // We need a Region to merge the exit from the peeled body and the // exit from the old loop body. RegionNode *r = new (C, 3) 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.hash_delete(useuse); _igvn._worklist.push(useuse); uint uses_found = 0; if( useuse->in(0) == use ) { useuse->set_req(0, r); uses_found++; if( useuse->is_CFG() ) { assert( dom_depth(useuse) > dd_r, "" ); set_idom(useuse, r, dom_depth(useuse)); } } for( uint k = 1; k < useuse->req(); k++ ) { if( useuse->in(k) == use ) { useuse->set_req(k, r); uses_found++; } } l -= uses_found; // we deleted 1 or more copies of this edge } // Now finish up 'r' r->set_req( 1, newuse ); r->set_req( 2, use ); _igvn.register_new_node_with_optimizer(r); set_loop(r, use_loop); set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r); } // End of if a loop-exit test } } // Step 4: If loop-invariant use is not control, it must be dominated by a // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region // there if needed. Make a Phi there merging old and new used values. Node_List *split_if_set = NULL; Node_List *split_bool_set = NULL; Node_List *split_cex_set = NULL; for( i = 0; i < loop->_body.size(); i++ ) { Node* old = loop->_body.at(i); Node* nnn = old_new[old->_idx]; // Copy uses to a worklist, so I can munge the def-use info // with impunity. for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++) worklist.push(old->fast_out(j)); while( worklist.size() ) { Node *use = worklist.pop(); if (!has_node(use)) continue; // Ignore dead nodes if (use->in(0) == C->top()) continue; IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use ); // Check for data-use outside of loop - at least one of OLD or USE // must not be a CFG node. if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) { // If the Data use is an IF, that means we have an IF outside of the // loop that is switching on a condition that is set inside of the // loop. Happens if people set a loop-exit flag; then test the flag // in the loop to break the loop, then test is again outside of the // loop to determine which way the loop exited. if( use->is_If() || use->is_CMove() ) { // Since this code is highly unlikely, we lazily build the worklist // of such Nodes to go split. if( !split_if_set ) split_if_set = new Node_List(area); split_if_set->push(use); } if( use->is_Bool() ) { if( !split_bool_set ) split_bool_set = new Node_List(area); split_bool_set->push(use); } if( use->Opcode() == Op_CreateEx ) { if( !split_cex_set ) split_cex_set = new Node_List(area); split_cex_set->push(use); } // Get "block" use is in uint idx = 0; while( use->in(idx) != old ) idx++; Node *prev = use->is_CFG() ? use : get_ctrl(use); assert( !loop->is_member( get_loop( prev ) ), "" ); Node *cfg = prev->_idx >= new_counter ? prev->in(2) : idom(prev); if( use->is_Phi() ) // Phi use is in prior block cfg = prev->in(idx); // NOT in block of Phi itself if (cfg->is_top()) { // Use is dead? _igvn.hash_delete(use); _igvn._worklist.push(use); use->set_req(idx, C->top()); continue; } while( !loop->is_member( get_loop( cfg ) ) ) { prev = cfg; cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg); } // If the use occurs after merging several exits from the loop, then // old value must have dominated all those exits. Since the same old // value was used on all those exits we did not need a Phi at this // merge point. NOW we do need a Phi here. Each loop exit value // is now merged with the peeled body exit; each exit gets its own // private Phi and those Phis need to be merged here. Node *phi; if( prev->is_Region() ) { if( idx == 0 ) { // Updating control edge? phi = prev; // Just use existing control } else { // Else need a new Phi phi = PhiNode::make( prev, old ); // Now recursively fix up the new uses of old! for( uint i = 1; i < prev->req(); i++ ) { worklist.push(phi); // Onto worklist once for each 'old' input } } } else { // Get new RegionNode merging old and new loop exits prev = old_new[prev->_idx]; assert( prev, "just made this in step 7" ); if( idx == 0 ) { // Updating control edge? phi = prev; // Just use existing control } else { // Else need a new Phi // Make a new Phi merging data values properly phi = PhiNode::make( prev, old ); phi->set_req( 1, nnn ); } } // If inserting a new Phi, check for prior hits if( idx != 0 ) { Node *hit = _igvn.hash_find_insert(phi); if( hit == NULL ) { _igvn.register_new_node_with_optimizer(phi); // Register new phi } else { // or // Remove the new phi from the graph and use the hit _igvn.remove_dead_node(phi); phi = hit; // Use existing phi } set_ctrl(phi, prev); } // Make 'use' use the Phi instead of the old loop body exit value _igvn.hash_delete(use); _igvn._worklist.push(use); use->set_req(idx, phi); if( use->_idx >= new_counter ) { // If updating new phis // Not needed for correctness, but prevents a weak assert // in AddPNode from tripping (when we end up with different // base & derived Phis that will become the same after // IGVN does CSE). Node *hit = _igvn.hash_find_insert(use); if( hit ) // Go ahead and re-hash for hits. _igvn.replace_node( use, hit ); } // If 'use' was in the loop-exit block, it now needs to be sunk // below the post-loop merge point. sink_use( use, prev ); } } } // Check for IFs that need splitting/cloning. Happens if an IF outside of // the loop uses a condition set in the loop. The original IF probably // takes control from one or more OLD Regions (which in turn get from NEW // Regions). In any case, there will be a set of Phis for each merge point // from the IF up to where the original BOOL def exists the loop. if( split_if_set ) { while( split_if_set->size() ) { Node *iff = split_if_set->pop(); if( iff->in(1)->is_Phi() ) { BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop ); _igvn.hash_delete(iff); _igvn._worklist.push(iff); iff->set_req(1, b); } } } if( split_bool_set ) { while( split_bool_set->size() ) { Node *b = split_bool_set->pop(); Node *phi = b->in(1); assert( phi->is_Phi(), "" ); CmpNode *cmp = clone_bool( (PhiNode*)phi, loop ); _igvn.hash_delete(b); _igvn._worklist.push(b); b->set_req(1, cmp); } } if( split_cex_set ) { while( split_cex_set->size() ) { Node *b = split_cex_set->pop(); assert( b->in(0)->is_Region(), "" ); assert( b->in(1)->is_Phi(), "" ); assert( b->in(0)->in(0) == b->in(1)->in(0), "" ); split_up( b, b->in(0), NULL ); } } } //---------------------- stride_of_possible_iv ------------------------------------- // Looks for an iff/bool/comp with one operand of the compare // being a cycle involving an add and a phi, // with an optional truncation (left-shift followed by a right-shift) // of the add. Returns zero if not an iv. int PhaseIdealLoop::stride_of_possible_iv(Node* iff) { Node* trunc1 = NULL; Node* trunc2 = NULL; const TypeInt* ttype = NULL; if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) { return 0; } BoolNode* bl = iff->in(1)->as_Bool(); Node* cmp = bl->in(1); if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) { return 0; } // Must have an invariant operand if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) { return 0; } Node* add2 = NULL; Node* cmp1 = cmp->in(1); if (cmp1->is_Phi()) { // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) ))) Node* phi = cmp1; for (uint i = 1; i < phi->req(); i++) { Node* in = phi->in(i); Node* add = CountedLoopNode::match_incr_with_optional_truncation(in, &trunc1, &trunc2, &ttype); if (add && add->in(1) == phi) { add2 = add->in(2); break; } } } else { // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) ))) Node* addtrunc = cmp1; Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc, &trunc1, &trunc2, &ttype); if (add && add->in(1)->is_Phi()) { Node* phi = add->in(1); for (uint i = 1; i < phi->req(); i++) { if (phi->in(i) == addtrunc) { add2 = add->in(2); break; } } } } if (add2 != NULL) { const TypeInt* add2t = _igvn.type(add2)->is_int(); if (add2t->is_con()) { return add2t->get_con(); } } return 0; } //---------------------- stay_in_loop ------------------------------------- // Return the (unique) control output node that's in the loop (if it exists.) Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) { Node* unique = NULL; if (!n) return NULL; for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { Node* use = n->fast_out(i); if (!has_ctrl(use) && loop->is_member(get_loop(use))) { if (unique != NULL) { return NULL; } unique = use; } } return unique; } //------------------------------ register_node ------------------------------------- // Utility to register node "n" with PhaseIdealLoop void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) { _igvn.register_new_node_with_optimizer(n); loop->_body.push(n); if (n->is_CFG()) { set_loop(n, loop); set_idom(n, pred, ddepth); } else { set_ctrl(n, pred); } } //------------------------------ proj_clone ------------------------------------- // Utility to create an if-projection ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) { ProjNode* c = p->clone()->as_Proj(); c->set_req(0, iff); return c; } //------------------------------ short_circuit_if ------------------------------------- // Force the iff control output to be the live_proj Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) { int proj_con = live_proj->_con; assert(proj_con == 0 || proj_con == 1, "false or true projection"); Node *con = _igvn.intcon(proj_con); set_ctrl(con, C->root()); if (iff) { iff->set_req(1, con); } return con; } //------------------------------ insert_if_before_proj ------------------------------------- // Insert a new if before an if projection (* - new node) // // before // if(test) // / \ // v v // other-proj proj (arg) // // after // if(test) // / \ // / v // | * proj-clone // v | // other-proj v // * new_if(relop(cmp[IU](left,right))) // / \ // v v // * new-proj proj // (returned) // ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) { IfNode* iff = proj->in(0)->as_If(); IdealLoopTree *loop = get_loop(proj); ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj(); int ddepth = dom_depth(proj); _igvn.hash_delete(iff); _igvn._worklist.push(iff); _igvn.hash_delete(proj); _igvn._worklist.push(proj); proj->set_req(0, NULL); // temporary disconnect ProjNode* proj2 = proj_clone(proj, iff); register_node(proj2, loop, iff, ddepth); Node* cmp = Signed ? (Node*) new (C,3)CmpINode(left, right) : (Node*) new (C,3)CmpUNode(left, right); register_node(cmp, loop, proj2, ddepth); BoolNode* bol = new (C,2)BoolNode(cmp, relop); register_node(bol, loop, proj2, ddepth); IfNode* new_if = new (C,2)IfNode(proj2, bol, iff->_prob, iff->_fcnt); register_node(new_if, loop, proj2, ddepth); proj->set_req(0, new_if); // reattach set_idom(proj, new_if, ddepth); ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj(); register_node(new_exit, get_loop(other_proj), new_if, ddepth); return new_exit; } //------------------------------ insert_region_before_proj ------------------------------------- // Insert a region before an if projection (* - new node) // // before // if(test) // / | // v | // proj v // other-proj // // after // if(test) // / | // v | // * proj-clone v // | other-proj // v // * new-region // | // v // * dum_if // / \ // v \ // * dum-proj v // proj // RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) { IfNode* iff = proj->in(0)->as_If(); IdealLoopTree *loop = get_loop(proj); ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj(); int ddepth = dom_depth(proj); _igvn.hash_delete(iff); _igvn._worklist.push(iff); _igvn.hash_delete(proj); _igvn._worklist.push(proj); proj->set_req(0, NULL); // temporary disconnect ProjNode* proj2 = proj_clone(proj, iff); register_node(proj2, loop, iff, ddepth); RegionNode* reg = new (C,2)RegionNode(2); reg->set_req(1, proj2); register_node(reg, loop, iff, ddepth); IfNode* dum_if = new (C,2)IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt); register_node(dum_if, loop, reg, ddepth); proj->set_req(0, dum_if); // reattach set_idom(proj, dum_if, ddepth); ProjNode* dum_proj = proj_clone(other_proj, dum_if); register_node(dum_proj, loop, dum_if, ddepth); return reg; } //------------------------------ insert_cmpi_loop_exit ------------------------------------- // Clone a signed compare loop exit from an unsigned compare and // insert it before the unsigned cmp on the stay-in-loop path. // All new nodes inserted in the dominator tree between the original // if and it's projections. The original if test is replaced with // a constant to force the stay-in-loop path. // // This is done to make sure that the original if and it's projections // still dominate the same set of control nodes, that the ctrl() relation // from data nodes to them is preserved, and that their loop nesting is // preserved. // // before // if(i 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 = stay_in_loop(if_cmpu, loop)->as_Proj(); ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj(); Node* limit = NULL; if (stride > 0) { limit = cmpu->in(2); } else { limit = _igvn.makecon(TypeInt::ZERO); set_ctrl(limit, C->root()); } // Create a new region on the exit path RegionNode* reg = insert_region_before_proj(lp_exit); // Clone the if-cmpu-true-false using a signed compare BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge; ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue); reg->add_req(cmpi_exit); // Clone the if-cmpu-true-false BoolTest::mask rel_u = bol->_test._test; ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue); reg->add_req(cmpu_exit); // Force original if to stay in loop. short_circuit_if(if_cmpu, lp_continue); return cmpi_exit->in(0)->as_If(); } //------------------------------ remove_cmpi_loop_exit ------------------------------------- // Remove a previously inserted signed compare loop exit. void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) { Node* lp_proj = stay_in_loop(if_cmp, loop); assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI && stay_in_loop(lp_proj, loop)->is_If() && stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu"); Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO); set_ctrl(con, C->root()); if_cmp->set_req(1, con); } //------------------------------ scheduled_nodelist ------------------------------------- // Create a post order schedule of nodes that are in the // "member" set. The list is returned in "sched". // The first node in "sched" is the loop head, followed by // nodes which have no inputs in the "member" set, and then // followed by the nodes that have an immediate input dependence // on a node in "sched". void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) { assert(member.test(loop->_head->_idx), "loop head must be in member set"); Arena *a = Thread::current()->resource_area(); VectorSet visited(a); Node_Stack nstack(a, loop->_body.size()); Node* n = loop->_head; // top of stack is cached in "n" uint idx = 0; visited.set(n->_idx); // Initially push all with no inputs from within member set for(uint i = 0; i < loop->_body.size(); i++ ) { Node *elt = loop->_body.at(i); if (member.test(elt->_idx)) { bool found = false; for (uint j = 0; j < elt->req(); j++) { Node* def = elt->in(j); if (def && member.test(def->_idx) && def != elt) { found = true; break; } } if (!found && elt != loop->_head) { nstack.push(n, idx); n = elt; assert(!visited.test(n->_idx), "not seen yet"); visited.set(n->_idx); } } } // traverse out's that are in the member set while (true) { if (idx < n->outcnt()) { Node* use = n->raw_out(idx); idx++; if (!visited.test_set(use->_idx)) { if (member.test(use->_idx)) { nstack.push(n, idx); n = use; idx = 0; } } } else { // All outputs processed sched.push(n); if (nstack.is_empty()) break; n = nstack.node(); idx = nstack.index(); nstack.pop(); } } } //------------------------------ has_use_in_set ------------------------------------- // Has a use in the vector set bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) { for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) { Node* use = n->fast_out(j); if (vset.test(use->_idx)) { return true; } } return false; } //------------------------------ has_use_internal_to_set ------------------------------------- // Has use internal to the vector set (ie. not in a phi at the loop head) bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) { Node* head = loop->_head; for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) { Node* use = n->fast_out(j); if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) { return true; } } return false; } //------------------------------ clone_for_use_outside_loop ------------------------------------- // clone "n" for uses that are outside of loop void PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) { assert(worklist.size() == 0, "should be empty"); for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) { Node* use = n->fast_out(j); if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) { worklist.push(use); } } while( worklist.size() ) { Node *use = worklist.pop(); if (!has_node(use) || use->in(0) == C->top()) continue; uint j; for (j = 0; j < use->req(); j++) { if (use->in(j) == n) break; } assert(j < use->req(), "must be there"); // clone "n" and insert it between the inputs of "n" and the use outside the loop Node* n_clone = n->clone(); _igvn.hash_delete(use); use->set_req(j, n_clone); _igvn._worklist.push(use); Node* use_c; if (!use->is_Phi()) { use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0); } else { // Use in a phi is considered a use in the associated predecessor block use_c = use->in(0)->in(j); } set_ctrl(n_clone, use_c); assert(!loop->is_member(get_loop(use_c)), "should be outside loop"); get_loop(use_c)->_body.push(n_clone); _igvn.register_new_node_with_optimizer(n_clone); #if !defined(PRODUCT) if (TracePartialPeeling) { tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx); } #endif } } //------------------------------ clone_for_special_use_inside_loop ------------------------------------- // clone "n" for special uses that are in the not_peeled region. // If these def-uses occur in separate blocks, the code generator // marks the method as not compilable. For example, if a "BoolNode" // is in a different basic block than the "IfNode" that uses it, then // the compilation is aborted in the code generator. void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n, VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) { if (n->is_Phi() || n->is_Load()) { return; } assert(worklist.size() == 0, "should be empty"); for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) { Node* use = n->fast_out(j); if ( not_peel.test(use->_idx) && (use->is_If() || use->is_CMove() || use->is_Bool()) && use->in(1) == n) { worklist.push(use); } } if (worklist.size() > 0) { // clone "n" and insert it between inputs of "n" and the use Node* n_clone = n->clone(); loop->_body.push(n_clone); _igvn.register_new_node_with_optimizer(n_clone); set_ctrl(n_clone, get_ctrl(n)); sink_list.push(n_clone); not_peel <<= n_clone->_idx; // add n_clone to not_peel set. #if !defined(PRODUCT) if (TracePartialPeeling) { tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx); } #endif while( worklist.size() ) { Node *use = worklist.pop(); _igvn.hash_delete(use); _igvn._worklist.push(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.hash_delete(use); _igvn._worklist.push(use); use->set_req(idx, phi); } #ifdef ASSERT //------------------------------ is_valid_loop_partition ------------------------------------- // Validate the loop partition sets: peel and not_peel bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel ) { uint i; // Check that peel_list entries are in the peel set for (i = 0; i < peel_list.size(); i++) { if (!peel.test(peel_list.at(i)->_idx)) { return false; } } // Check at loop members are in one of peel set or not_peel set for (i = 0; i < loop->_body.size(); i++ ) { Node *def = loop->_body.at(i); uint di = def->_idx; // Check that peel set elements are in peel_list if (peel.test(di)) { if (not_peel.test(di)) { return false; } // Must be in peel_list also bool found = false; for (uint j = 0; j < peel_list.size(); j++) { if (peel_list.at(j)->_idx == di) { found = true; break; } } if (!found) { return false; } } else if (not_peel.test(di)) { if (peel.test(di)) { return false; } } else { return false; } } return true; } //------------------------------ is_valid_clone_loop_exit_use ------------------------------------- // Ensure a use outside of loop is of the right form bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) { Node *use_c = has_ctrl(use) ? get_ctrl(use) : use; return (use->is_Phi() && use_c->is_Region() && use_c->req() == 3 && (use_c->in(exit_idx)->Opcode() == Op_IfTrue || use_c->in(exit_idx)->Opcode() == Op_IfFalse || use_c->in(exit_idx)->Opcode() == Op_JumpProj) && loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) ); } //------------------------------ is_valid_clone_loop_form ------------------------------------- // Ensure that all uses outside of loop are of the right form bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list, uint orig_exit_idx, uint clone_exit_idx) { uint len = peel_list.size(); for (uint i = 0; i < len; i++) { Node *def = peel_list.at(i); for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) { Node *use = def->fast_out(j); Node *use_c = has_ctrl(use) ? get_ctrl(use) : use; if (!loop->is_member(get_loop(use_c))) { // use is not in the loop, check for correct structure if (use->in(0) == def) { // Okay } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) { return false; } } } } return true; } #endif //------------------------------ partial_peel ------------------------------------- // Partially peel (aka loop rotation) the top portion of a loop (called // the peel section below) by cloning it and placing one copy just before // the new loop head and the other copy at the bottom of the new loop. // // before after where it came from // // stmt1 stmt1 // loop: stmt2 clone // stmt2 if condA goto exitA clone // if condA goto exitA new_loop: new // stmt3 stmt3 clone // if !condB goto loop if condB goto exitB clone // exitB: stmt2 orig // stmt4 if !condA goto new_loop orig // exitA: goto exitA // exitB: // stmt4 // exitA: // // Step 1: find the cut point: an exit test on probable // induction variable. // Step 2: schedule (with cloning) operations in the peel // section that can be executed after the cut into // the section that is not peeled. This may need // to clone operations into exit blocks. For // instance, a reference to A[i] in the not-peel // section and a reference to B[i] in an exit block // may cause a left-shift of i by 2 to be placed // in the peel block. This step will clone the left // shift into the exit block and sink the left shift // from the peel to the not-peel section. // Step 3: clone the loop, retarget the control, and insert // phis for values that are live across the new loop // head. This is very dependent on the graph structure // from clone_loop. It creates region nodes for // exit control and associated phi nodes for values // flow out of the loop through that exit. The region // node is dominated by the clone's control projection. // So the clone's peel section is placed before the // new loop head, and the clone's not-peel section is // forms the top part of the new loop. The original // peel section forms the tail of the new loop. // Step 4: update the dominator tree and recompute the // dominator depth. // // orig // // stmt1 // | // v // loop predicate // | // v // loop<----+ // | | // stmt2 | // | | // v | // ifA | // / | | // v v | // false true ^ <-- last_peel // / | | // / ===|==cut | // / stmt3 | <-- first_not_peel // / | | // | v | // v ifB | // exitA: / \ | // / \ | // v v | // false true | // / \ | // / ----+ // | // v // exitB: // stmt4 // // // after clone loop // // stmt1 // | // v // loop predicate // / \ // clone / \ orig // / \ // / \ // v v // +---->loop loop<----+ // | | | | // | stmt2 stmt2 | // | | | | // | v v | // | ifA ifA | // | | \ / | | // | v v v v | // ^ true false false true ^ <-- last_peel // | | ^ \ / | | // | cut==|== \ \ / ===|==cut | // | stmt3 \ \ / stmt3 | <-- first_not_peel // | | dom | | | | // | v \ 1v v2 v | // | ifB regionA ifB | // | / \ | / \ | // | / \ v / \ | // | v v exitA: v v | // | true false false true | // | / ^ \ / \ | // +---- \ \ / ----+ // dom \ / // \ 1v v2 // regionB // | // v // exitB: // stmt4 // // // after partial peel // // stmt1 // | // v // loop predicate // / // clone / orig // / TOP // / \ // v v // TOP->loop loop----+ // | | | // stmt2 stmt2 | // | | | // v v | // ifA ifA | // | \ / | | // v v v v | // true false false true | <-- last_peel // | ^ \ / +------|---+ // +->newloop \ \ / === ==cut | | // | stmt3 \ \ / TOP | | // | | dom | | stmt3 | | <-- first_not_peel // | v \ 1v v2 v | | // | ifB regionA ifB ^ v // | / \ | / \ | | // | / \ v / \ | | // | v v exitA: v v | | // | true false false true | | // | / ^ \ / \ | | // | | \ \ / v | | // | | dom \ / TOP | | // | | \ 1v v2 | | // ^ v regionB | | // | | | | | // | | v ^ v // | | exitB: | | // | | stmt4 | | // | +------------>-----------------+ | // | | // +-----------------<---------------------+ // // // final graph // // stmt1 // | // v // loop predicate // | // v // stmt2 clone // | // v // ........> ifA clone // : / | // dom / | // : v v // : false true // : | | // : | v // : | newloop<-----+ // : | | | // : | stmt3 clone | // : | | | // : | v | // : | ifB | // : | / \ | // : | v v | // : | false true | // : | | | | // : | v stmt2 | // : | exitB: | | // : | stmt4 v | // : | ifA orig | // : | / \ | // : | / \ | // : | v v | // : | false true | // : | / \ | // : v v -----+ // RegionA // | // v // exitA // bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) { assert(!loop->_head->is_CountedLoop(), "Non-counted loop only"); if (!loop->_head->is_Loop()) { return false; } LoopNode *head = loop->_head->as_Loop(); if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) { return false; } // Check for complex exit control for(uint ii = 0; ii < loop->_body.size(); ii++ ) { Node *n = loop->_body.at(ii); int opc = n->Opcode(); if (n->is_Call() || opc == Op_Catch || opc == Op_CatchProj || opc == Op_Jump || opc == Op_JumpProj) { #if !defined(PRODUCT) if (TracePartialPeeling) { tty->print_cr("\nExit control too complex: lp: %d", head->_idx); } #endif return false; } } int dd = dom_depth(head); // Step 1: find cut point // Walk up dominators to loop head looking for first loop exit // which is executed on every path thru loop. IfNode *peel_if = NULL; IfNode *peel_if_cmpu = NULL; Node *iff = loop->tail(); while( iff != head ) { if( iff->is_If() ) { Node *ctrl = get_ctrl(iff->in(1)); if (ctrl->is_top()) return false; // Dead test on live IF. // If loop-varying exit-test, check for induction variable if( loop->is_member(get_loop(ctrl)) && loop->is_loop_exit(iff) && is_possible_iv_test(iff)) { Node* cmp = iff->in(1)->in(1); if (cmp->Opcode() == Op_CmpI) { peel_if = iff->as_If(); } else { assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU"); peel_if_cmpu = iff->as_If(); } } } iff = idom(iff); } // Prefer signed compare over unsigned compare. IfNode* new_peel_if = NULL; if (peel_if == NULL) { if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) { return false; // No peel point found } new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop); if (new_peel_if == NULL) { return false; // No peel point found } peel_if = new_peel_if; } Node* last_peel = stay_in_loop(peel_if, loop); Node* first_not_peeled = stay_in_loop(last_peel, loop); if (first_not_peeled == NULL || first_not_peeled == head) { return false; } #if !defined(PRODUCT) if (TraceLoopOpts) { tty->print("PartialPeel "); loop->dump_head(); } if (TracePartialPeeling) { tty->print_cr("before partial peel one iteration"); Node_List wl; Node* t = head->in(2); while (true) { wl.push(t); if (t == head) break; t = idom(t); } while (wl.size() > 0) { Node* tt = wl.pop(); tt->dump(); if (tt == last_peel) tty->print_cr("-- cut --"); } } #endif ResourceArea *area = Thread::current()->resource_area(); VectorSet peel(area); VectorSet not_peel(area); Node_List peel_list(area); Node_List worklist(area); Node_List sink_list(area); // Set of cfg nodes to peel are those that are executable from // the head through last_peel. assert(worklist.size() == 0, "should be empty"); worklist.push(head); peel.set(head->_idx); while (worklist.size() > 0) { Node *n = worklist.pop(); if (n != last_peel) { for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) { Node* use = n->fast_out(j); if (use->is_CFG() && loop->is_member(get_loop(use)) && !peel.test_set(use->_idx)) { worklist.push(use); } } } } // Set of non-cfg nodes to peel are those that are control // dependent on the cfg nodes. uint i; for(i = 0; i < loop->_body.size(); i++ ) { Node *n = loop->_body.at(i); Node *n_c = has_ctrl(n) ? get_ctrl(n) : n; if (peel.test(n_c->_idx)) { peel.set(n->_idx); } else { not_peel.set(n->_idx); } } // Step 2: move operations from the peeled section down into the // not-peeled section // Get a post order schedule of nodes in the peel region // Result in right-most operand. scheduled_nodelist(loop, peel, peel_list ); assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition"); // For future check for too many new phis uint old_phi_cnt = 0; for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) { Node* use = head->fast_out(j); if (use->is_Phi()) old_phi_cnt++; } #if !defined(PRODUCT) if (TracePartialPeeling) { tty->print_cr("\npeeled list"); } #endif // Evacuate nodes in peel region into the not_peeled region if possible uint new_phi_cnt = 0; for (i = 0; i < peel_list.size();) { Node* n = peel_list.at(i); #if !defined(PRODUCT) if (TracePartialPeeling) n->dump(); #endif bool incr = true; if ( !n->is_CFG() ) { if ( has_use_in_set(n, not_peel) ) { // If not used internal to the peeled region, // move "n" from peeled to not_peeled region. if ( !has_use_internal_to_set(n, peel, loop) ) { // if not pinned and not a load (which maybe anti-dependent on a store) // and not a CMove (Matcher expects only bool->cmove). if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) { clone_for_use_outside_loop( loop, n, worklist ); sink_list.push(n); peel >>= n->_idx; // delete n from peel set. not_peel <<= n->_idx; // add n to not_peel set. peel_list.remove(i); incr = false; #if !defined(PRODUCT) if (TracePartialPeeling) { tty->print_cr("sink to not_peeled region: %d newbb: %d", n->_idx, get_ctrl(n)->_idx); } #endif } } else { // Otherwise check for special def-use cases that span // the peel/not_peel boundary such as bool->if clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist ); new_phi_cnt++; } } } if (incr) i++; } if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) { #if !defined(PRODUCT) if (TracePartialPeeling) { tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c", new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F'); } #endif if (new_peel_if != NULL) { remove_cmpi_loop_exit(new_peel_if, loop); } // Inhibit more partial peeling on this loop assert(!head->is_partial_peel_loop(), "not partial peeled"); head->mark_partial_peel_failed(); return false; } // Step 3: clone loop, retarget control, and insert new phis // Create new loop head for new phis and to hang // the nodes being moved (sinked) from the peel region. LoopNode* new_head = new (C, 3) LoopNode(last_peel, last_peel); new_head->set_unswitch_count(head->unswitch_count()); // Preserve _igvn.register_new_node_with_optimizer(new_head); assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled"); first_not_peeled->set_req(0, new_head); set_loop(new_head, loop); loop->_body.push(new_head); not_peel.set(new_head->_idx); set_idom(new_head, last_peel, dom_depth(first_not_peeled)); set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled)); while (sink_list.size() > 0) { Node* n = sink_list.pop(); set_ctrl(n, new_head); } assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition"); clone_loop( loop, old_new, dd ); const uint clone_exit_idx = 1; const uint orig_exit_idx = 2; assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop"); Node* head_clone = old_new[head->_idx]; LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop(); Node* orig_tail_clone = head_clone->in(2); // Add phi if "def" node is in peel set and "use" is not for(i = 0; i < peel_list.size(); i++ ) { Node *def = peel_list.at(i); if (!def->is_CFG()) { for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) { Node *use = def->fast_out(j); if (has_node(use) && use->in(0) != C->top() && (!peel.test(use->_idx) || (use->is_Phi() && use->in(0) == head)) ) { worklist.push(use); } } while( worklist.size() ) { Node *use = worklist.pop(); for (uint j = 1; j < use->req(); j++) { Node* n = use->in(j); if (n == def) { // "def" is in peel set, "use" is not in peel set // or "use" is in the entry boundary (a phi) of the peel set Node* use_c = has_ctrl(use) ? get_ctrl(use) : use; if ( loop->is_member(get_loop( use_c )) ) { // use is in loop if (old_new[use->_idx] != NULL) { // null for dead code Node* use_clone = old_new[use->_idx]; _igvn.hash_delete(use); use->set_req(j, C->top()); _igvn._worklist.push(use); insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone ); } } else { assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format"); // use is not in the loop, check if the live range includes the cut Node* lp_if = use_c->in(orig_exit_idx)->in(0); if (not_peel.test(lp_if->_idx)) { assert(j == orig_exit_idx, "use from original loop"); insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone ); } } } } } } } // Step 3b: retarget control // Redirect control to the new loop head if a cloned node in // the not_peeled region has control that points into the peeled region. // This necessary because the cloned peeled region will be outside // the loop. // from to // cloned-peeled <---+ // new_head_clone: | <--+ // cloned-not_peeled in(0) in(0) // orig-peeled for(i = 0; i < loop->_body.size(); i++ ) { Node *n = loop->_body.at(i); if (!n->is_CFG() && n->in(0) != NULL && not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) { Node* n_clone = old_new[n->_idx]; _igvn.hash_delete(n_clone); n_clone->set_req(0, new_head_clone); _igvn._worklist.push(n_clone); } } // Backedge of the surviving new_head (the clone) is original last_peel _igvn.hash_delete(new_head_clone); new_head_clone->set_req(LoopNode::LoopBackControl, last_peel); _igvn._worklist.push(new_head_clone); // Cut first node in original not_peel set _igvn.hash_delete(new_head); new_head->set_req(LoopNode::EntryControl, C->top()); new_head->set_req(LoopNode::LoopBackControl, C->top()); _igvn._worklist.push(new_head); // Copy head_clone back-branch info to original head // and remove original head's loop entry and // clone head's back-branch _igvn.hash_delete(head); _igvn.hash_delete(head_clone); head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl)); head->set_req(LoopNode::LoopBackControl, C->top()); head_clone->set_req(LoopNode::LoopBackControl, C->top()); _igvn._worklist.push(head); _igvn._worklist.push(head_clone); // 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.hash_delete(use); _igvn.hash_delete(use_clone); use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl)); use->set_req(LoopNode::LoopBackControl, C->top()); use_clone->set_req(LoopNode::LoopBackControl, C->top()); _igvn._worklist.push(use); _igvn._worklist.push(use_clone); } } // Step 4: update dominator tree and dominator depth set_idom(head, orig_tail_clone, dd); recompute_dom_depth(); // Inhibit more partial peeling on this loop new_head_clone->set_partial_peel_loop(); C->set_major_progress(); #if !defined(PRODUCT) if (TracePartialPeeling) { tty->print_cr("\nafter partial peel one iteration"); Node_List wl(area); Node* t = last_peel; while (true) { wl.push(t); if (t == head_clone) break; t = idom(t); } while (wl.size() > 0) { Node* tt = wl.pop(); if (tt == head) tty->print_cr("orig head"); else if (tt == new_head_clone) tty->print_cr("new head"); else if (tt == head_clone) tty->print_cr("clone head"); tt->dump(); } } #endif return true; } //------------------------------reorg_offsets---------------------------------- // Reorganize offset computations to lower register pressure. Mostly // prevent loop-fallout uses of the pre-incremented trip counter (which are // then alive with the post-incremented trip counter forcing an extra // register move) void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) { // Perform it only for canonical counted loops. // Loop's shape could be messed up by iteration_split_impl. if (!loop->_head->is_CountedLoop()) return; if (!loop->_head->as_Loop()->is_valid_counted_loop()) return; CountedLoopNode *cl = loop->_head->as_CountedLoop(); CountedLoopEndNode *cle = cl->loopexit(); Node *exit = cle->proj_out(false); Node *phi = cl->phi(); // Check for the special case of folks using the pre-incremented // trip-counter on the fall-out path (forces the pre-incremented // and post-incremented trip counter to be live at the same time). // Fix this by adjusting to use the post-increment trip counter. bool progress = true; while (progress) { progress = false; for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) { Node* use = phi->fast_out(i); // User of trip-counter if (!has_ctrl(use)) continue; Node *u_ctrl = get_ctrl(use); if (use->is_Phi()) { u_ctrl = NULL; for (uint j = 1; j < use->req(); j++) if (use->in(j) == phi) u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j)); } IdealLoopTree *u_loop = get_loop(u_ctrl); // Look for loop-invariant use if (u_loop == loop) continue; if (loop->is_member(u_loop)) continue; // Check that use is live out the bottom. Assuming the trip-counter // update is right at the bottom, uses of of the loop middle are ok. if (dom_lca(exit, u_ctrl) != exit) continue; // Hit! Refactor use to use the post-incremented tripcounter. // Compute a post-increment tripcounter. Node *opaq = new (C, 2) Opaque2Node( C, cle->incr() ); register_new_node( opaq, u_ctrl ); Node *neg_stride = _igvn.intcon(-cle->stride_con()); set_ctrl(neg_stride, C->root()); Node *post = new (C, 3) AddINode( opaq, neg_stride); register_new_node( post, u_ctrl ); _igvn.hash_delete(use); _igvn._worklist.push(use); for (uint j = 1; j < use->req(); j++) { if (use->in(j) == phi) use->set_req(j, post); } // Since DU info changed, rerun loop progress = true; break; } } }