diff -r 000000000000 -r a61af66fc99e src/share/vm/opto/loopopts.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/opto/loopopts.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,2677 @@ +/* + * Copyright 1999-2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +#include "incls/_precompiled.incl" +#include "incls/_loopopts.cpp.incl" + +//============================================================================= +//------------------------------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 ) { + int wins = 0; + assert( !n->is_CFG(), "" ); + assert( region->is_Region(), "" ); + Node *phi = new (C, region->req()) PhiNode( region, n->bottom_type() ); + 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); + 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; + + // The occasional new node + if( x->_idx >= old_unique ) { // Found a new, unplaced node? + old_ctrl = x->is_Con() ? C->root() : NULL; + old_loop = NULL; // Not in any prior loop + } else { + old_ctrl = x->is_Con() ? C->root() : 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) ); + // Set new location + set_ctrl(x, new_ctrl); + IdealLoopTree *new_loop = get_loop( 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 ) { +#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, "" ); + // '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 = ((IfNode*)iff)->proj_out(pop == Op_IfTrue); + 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 ); + register_new_node( inv_scale, add_invar_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.hash_delete( n ); + _igvn.subsume_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.hash_delete( n ); + _igvn.subsume_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.hash_delete( n ); + _igvn.subsume_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 highly predictable branch. No point in CMOV'ing if + // we are going to predict accurately all the time. + // %%% This hides patterns produced by utility methods like Math.min. + if( iff->_prob < PROB_UNLIKELY_MAG(3) || + iff->_prob > PROB_LIKELY_MAG(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; + + // Check profitability + int cost = 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 + PhiNode* phi = out->as_Phi(); + switch (phi->type()->basic_type()) { + case T_LONG: + cost++; // Probably encodes as 2 CMOV's + case T_INT: // These all CMOV fine + case T_FLOAT: + case T_DOUBLE: + case T_ADDRESS: // (RawPtr) + cost++; + break; + case T_OBJECT: { // Base oops are OK, but not derived oops + const TypeOopPtr *tp = phi->type()->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) + return NULL; // Too much speculative goo + } + } + // See if the Phi is used by a Cmp. 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() ) + return NULL; + } + } + if( cost >= ConditionalMoveLimit ) return NULL; // Too much goo + + // -------------- + // 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.hash_delete(phi); + _igvn.subsume_node( phi, cmov ); +#ifndef PRODUCT + 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_op == Op_StorePConditional || n_op == Op_StoreLConditional || n_op == Op_CompareAndSwapI || n_op == Op_CompareAndSwapL ||n_op == Op_CompareAndSwapP) 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.hash_delete(n); + _igvn.subsume_node( n, phi ); + // Moved a load around the loop, 'en-registering' something. + if( n_blk->Opcode() == Op_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; + } +} + +#ifdef _LP64 +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. + 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) { + return false; + } + } + } + } + return true; +} +#endif + + +//------------------------------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; + +#ifdef _LP64 + // Check for safety of the merge point. + if( !merge_point_safe(n_ctrl) ) { + return; + } +#endif + + // 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.hash_delete(n); + _igvn.subsume_node( n, phi ); + + // Now split the bool up thru the phi + Node *bolphi = split_thru_phi( bol, n_ctrl, -1 ); + _igvn.hash_delete(bol); + _igvn.subsume_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.hash_delete(iff); + _igvn.subsume_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 ); +#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 seperate 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() ) _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.add_users_to_worklist(n); + _igvn.hash_delete(n); + _igvn.subsume_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.subsume_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); + if (!use->is_Phi()) { + Node* use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0); + 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); + } else { + // Use in a phi is considered a use in the associated predecessor block + Node *prevbb = use->in(0)->in(j); + set_ctrl(n_clone, prevbb); + assert(!loop->is_member(get_loop(prevbb)), "should be outside loop"); + get_loop(prevbb)->_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<----+ +// | | +// 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 +// / \ +// 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 +// / +// clone / orig +// / TOP +// / \ +// v v +// TOP->region region----+ +// | | | +// 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 +// ........> ifA clone +// : / | +// dom / | +// : v v +// : false true +// : | | +// : | stmt2 clone +// : | | +// : | 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 ) { + + 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 (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); + _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 ) { + + CountedLoopNode *cl = loop->_head->as_CountedLoop(); + CountedLoopEndNode *cle = cl->loopexit(); + if( !cle ) return; // The occasional dead loop + // Find loop exit control + Node *exit = cle->proj_out(false); + assert( exit->Opcode() == Op_IfFalse, "" ); + + // 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. + Node *phi = cl->phi(); + if( !phi ) return; // Dead infinite loop + 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; + // protect against stride not being a constant + if( !cle->stride_is_con() ) continue; + // Hit! Refactor use to use the post-incremented tripcounter. + // Compute a post-increment tripcounter. + Node *opaq = new (C, 2) Opaque2Node( 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; + } + } + +}