//------------------------------split_up--------------------------------------- // Split block-local op up through the phis to empty the current block bool PhaseIdealLoop::split_up( Node *n, Node *blk1, Node *blk2 ) { if( n->is_CFG() ) { assert( n->in(0) != blk1, "Lousy candidate for split-if" ); return false; } if( get_ctrl(n) != blk1 && get_ctrl(n) != blk2 ) return false; // Not block local if( n->is_Phi() ) return false; // Local PHIs are expected // Recursively split-up inputs for (uint i = 1; i < n->req(); i++) { if( split_up( n->in(i), blk1, blk2 ) ) { // Got split recursively and self went dead? if (n->outcnt() == 0) _igvn.remove_dead_node(n); return true; } } // Check for needing to clone-up a compare. Can't do that, it forces // another (nested) split-if transform. Instead, clone it "down". if( n->is_Cmp() ) { assert(get_ctrl(n) == blk2 || get_ctrl(n) == blk1, "must be in block with IF"); // Check for simple Cmp/Bool/CMove which we can clone-up. Cmp/Bool/CMove // sequence can have no other users and it must all reside in the split-if // block. Non-simple Cmp/Bool/CMove sequences are 'cloned-down' below - // private, per-use versions of the Cmp and Bool are made. These sink to // the CMove block. If the CMove is in the split-if block, then in the // next iteration this will become a simple Cmp/Bool/CMove set to clone-up. Node *bol, *cmov; if( !(n->outcnt() == 1 && n->unique_out()->is_Bool() && (bol = n->unique_out()->as_Bool()) && (get_ctrl(bol) == blk1 || get_ctrl(bol) == blk2) && bol->outcnt() == 1 && bol->unique_out()->is_CMove() && (cmov = bol->unique_out()->as_CMove()) && (get_ctrl(cmov) == blk1 || get_ctrl(cmov) == blk2) ) ) { // Must clone down #ifndef PRODUCT if( PrintOpto && VerifyLoopOptimizations ) { tty->print("Cloning down: "); n->dump(); } #endif // Clone down any block-local BoolNode uses of this CmpNode for (DUIterator i = n->outs(); n->has_out(i); i++) { Node* bol = n->out(i); assert( bol->is_Bool(), "" ); if (bol->outcnt() == 1) { Node* use = bol->unique_out(); Node *use_c = use->is_If() ? use->in(0) : get_ctrl(use); if (use_c == blk1 || use_c == blk2) { continue; } } if (get_ctrl(bol) == blk1 || get_ctrl(bol) == blk2) { // Recursively sink any BoolNode #ifndef PRODUCT if( PrintOpto && VerifyLoopOptimizations ) { tty->print("Cloning down: "); bol->dump(); } #endif for (DUIterator_Last jmin, j = bol->last_outs(jmin); j >= jmin; --j) { // Uses are either IfNodes or CMoves Node* iff = bol->last_out(j); assert( iff->in(1) == bol, "" ); // Get control block of either the CMove or the If input Node *iff_ctrl = iff->is_If() ? iff->in(0) : get_ctrl(iff); Node *x = bol->clone(); register_new_node(x, iff_ctrl); _igvn.hash_delete(iff); iff->set_req(1, x); _igvn._worklist.push(iff); } _igvn.remove_dead_node( bol ); --i; } } // Clone down this CmpNode for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; --j) { Node* bol = n->last_out(j); assert( bol->in(1) == n, "" ); Node *x = n->clone(); register_new_node(x, get_ctrl(bol)); _igvn.hash_delete(bol); bol->set_req(1, x); _igvn._worklist.push(bol); } _igvn.remove_dead_node( n ); return true; } } // See if splitting-up a Store. Any anti-dep loads must go up as // well. An anti-dep load might be in the wrong block, because in // this particular layout/schedule we ignored anti-deps and allow // memory to be alive twice. This only works if we do the same // operations on anti-dep loads as we do their killing stores. if( n->is_Store() && n->in(MemNode::Memory)->in(0) == n->in(0) ) { // Get store's memory slice int alias_idx = C->get_alias_index(_igvn.type(n->in(MemNode::Address))->is_ptr()); // Get memory-phi anti-dep loads will be using Node *memphi = n->in(MemNode::Memory); assert( memphi->is_Phi(), "" ); // Hoist any anti-dep load to the splitting block; // it will then "split-up". for (DUIterator_Fast imax,i = memphi->fast_outs(imax); i < imax; i++) { Node *load = memphi->fast_out(i); if( load->is_Load() && alias_idx == C->get_alias_index(_igvn.type(load->in(MemNode::Address))->is_ptr()) ) set_ctrl(load,blk1); } } // Found some other Node; must clone it up #ifndef PRODUCT if( PrintOpto && VerifyLoopOptimizations ) { tty->print("Cloning up: "); n->dump(); } #endif // Now actually split-up this guy. One copy per control path merging. Node *phi = PhiNode::make_blank(blk1, n); for( uint j = 1; j < blk1->req(); j++ ) { Node *x = n->clone(); if( n->in(0) && n->in(0) == blk1 ) x->set_req( 0, blk1->in(j) ); for( uint i = 1; i < n->req(); i++ ) { Node *m = n->in(i); if( get_ctrl(m) == blk1 ) { assert( m->in(0) == blk1, "" ); x->set_req( i, m->in(j) ); } } register_new_node( x, blk1->in(j) ); phi->init_req( j, x ); } // Announce phi to optimizer register_new_node(phi, blk1); // Remove cloned-up value from optimizer; use phi instead _igvn.hash_delete(n); _igvn.subsume_node( n, phi ); // (There used to be a self-recursive call to split_up() here, // but it is not needed. All necessary forward walking is done // by do_split_if() below.) return true; }
//------------------------------do_unswitching----------------------------- // Clone loop with an invariant test (that does not exit) and // insert a clone of the test that selects which version to // execute. void PhaseIdealLoop::do_unswitching (IdealLoopTree *loop, Node_List &old_new) { // Find first invariant test that doesn't exit the loop LoopNode *head = loop->_head->as_Loop(); IfNode* unswitch_iff = find_unswitching_candidate((const IdealLoopTree *)loop); assert(unswitch_iff != NULL, "should be at least one"); // Need to revert back to normal loop if (head->is_CountedLoop() && !head->as_CountedLoop()->is_normal_loop()) { head->as_CountedLoop()->set_normal_loop(); } ProjNode* proj_true = create_slow_version_of_loop(loop, old_new); assert(proj_true->is_IfTrue() && proj_true->unique_ctrl_out() == head, "by construction"); // Increment unswitch count LoopNode* head_clone = old_new[head->_idx]->as_Loop(); int nct = head->unswitch_count() + 1; head->set_unswitch_count(nct); head_clone->set_unswitch_count(nct); // Add test to new "if" outside of loop IfNode* invar_iff = proj_true->in(0)->as_If(); Node* invar_iff_c = invar_iff->in(0); BoolNode* bol = unswitch_iff->in(1)->as_Bool(); invar_iff->set_req(1, bol); invar_iff->_prob = unswitch_iff->_prob; ProjNode* proj_false = invar_iff->proj_out(0)->as_Proj(); // Hoist invariant casts out of each loop to the appropriate // control projection. Node_List worklist; for (DUIterator_Fast imax, i = unswitch_iff->fast_outs(imax); i < imax; i++) { ProjNode* proj= unswitch_iff->fast_out(i)->as_Proj(); // Copy to a worklist for easier manipulation for (DUIterator_Fast jmax, j = proj->fast_outs(jmax); j < jmax; j++) { Node* use = proj->fast_out(j); if (use->Opcode() == Op_CheckCastPP && loop->is_invariant(use->in(1))) { worklist.push(use); } } ProjNode* invar_proj = invar_iff->proj_out(proj->_con)->as_Proj(); while (worklist.size() > 0) { Node* use = worklist.pop(); Node* nuse = use->clone(); nuse->set_req(0, invar_proj); _igvn.hash_delete(use); use->set_req(1, nuse); _igvn._worklist.push(use); register_new_node(nuse, invar_proj); // Same for the clone Node* use_clone = old_new[use->_idx]; _igvn.hash_delete(use_clone); use_clone->set_req(1, nuse); _igvn._worklist.push(use_clone); } } // Hardwire the control paths in the loops into if(true) and if(false) _igvn.hash_delete(unswitch_iff); short_circuit_if(unswitch_iff, proj_true); _igvn._worklist.push(unswitch_iff); IfNode* unswitch_iff_clone = old_new[unswitch_iff->_idx]->as_If(); _igvn.hash_delete(unswitch_iff_clone); short_circuit_if(unswitch_iff_clone, proj_false); _igvn._worklist.push(unswitch_iff_clone); // Reoptimize loops loop->record_for_igvn(); for(int i = loop->_body.size() - 1; i >= 0 ; i--) { Node *n = loop->_body[i]; Node *n_clone = old_new[n->_idx]; _igvn._worklist.push(n_clone); } #ifndef PRODUCT if (TraceLoopUnswitching) { tty->print_cr("Loop unswitching orig: %d @ %d new: %d @ %d", head->_idx, unswitch_iff->_idx, old_new[head->_idx]->_idx, unswitch_iff_clone->_idx); } #endif C->set_major_progress(); }
// We must be at the merge point which post-dominates 'new_false' and // 'new_true'. Figure out which edges into the RegionNode eventually lead up // to false and which to true. Put in a PhiNode to merge values; plug in // the appropriate false-arm or true-arm values. If some path leads to the // original IF, then insert a Phi recursively. Node *PhaseIdealLoop::spinup( Node *iff_dom, Node *new_false, Node *new_true, Node *use_blk, Node *def, small_cache *cache ) { if (use_blk->is_top()) // Handle dead uses return use_blk; Node *prior_n = (Node*)0xdeadbeef; Node *n = use_blk; // Get path input assert( use_blk != iff_dom, "" ); // Here's the "spinup" the dominator tree loop. Do a cache-check // along the way, in case we've come this way before. while( n != iff_dom ) { // Found post-dominating point? prior_n = n; n = idom(n); // Search higher Node *s = cache->probe( prior_n ); // Check cache if( s ) return s; // Cache hit! } Node *phi_post; if( prior_n == new_false || prior_n == new_true ) { phi_post = def->clone(); phi_post->set_req(0, prior_n ); register_new_node(phi_post, prior_n); } else { // This method handles both control uses (looking for Regions) or data // uses (looking for Phis). If looking for a control use, then we need // to insert a Region instead of a Phi; however Regions always exist // previously (the hash_find_insert below would always hit) so we can // return the existing Region. if( def->is_CFG() ) { phi_post = prior_n; // If looking for CFG, return prior } else { assert( def->is_Phi(), "" ); assert( prior_n->is_Region(), "must be a post-dominating merge point" ); // Need a Phi here phi_post = PhiNode::make_blank(prior_n, def); // Search for both true and false on all paths till find one. for( uint i = 1; i < phi_post->req(); i++ ) // For all paths phi_post->init_req( i, spinup( iff_dom, new_false, new_true, prior_n->in(i), def, cache ) ); Node *t = _igvn.hash_find_insert(phi_post); if( t ) { // See if we already have this one // phi_post will not be used, so kill it _igvn.remove_dead_node(phi_post); phi_post->destruct(); phi_post = t; } else { register_new_node( phi_post, prior_n ); } } } // Update cache everywhere prior_n = (Node*)0xdeadbeef; // Reset IDOM walk n = use_blk; // Get path input // Spin-up the idom tree again, basically doing path-compression. // Insert cache entries along the way, so that if we ever hit this // point in the IDOM tree again we'll stop immediately on a cache hit. while( n != iff_dom ) { // Found post-dominating point? prior_n = n; n = idom(n); // Search higher cache->lru_insert( prior_n, phi_post ); // Fill cache } // End of while not gone high enough return phi_post; }