/* * Copyright 1998-2009 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. * */ class CmpNode; class CountedLoopEndNode; class CountedLoopNode; class IdealLoopTree; class LoopNode; class Node; class PhaseIdealLoop; class VectorSet; class Invariance; struct small_cache; // // I D E A L I Z E D L O O P S // // Idealized loops are the set of loops I perform more interesting // transformations on, beyond simple hoisting. //------------------------------LoopNode--------------------------------------- // Simple loop header. Fall in path on left, loop-back path on right. class LoopNode : public RegionNode { // Size is bigger to hold the flags. However, the flags do not change // the semantics so it does not appear in the hash & cmp functions. virtual uint size_of() const { return sizeof(*this); } protected: short _loop_flags; // Names for flag bitfields enum { pre_post_main=0, inner_loop=8, partial_peel_loop=16, partial_peel_failed=32 }; char _unswitch_count; enum { _unswitch_max=3 }; public: // Names for edge indices enum { Self=0, EntryControl, LoopBackControl }; int is_inner_loop() const { return _loop_flags & inner_loop; } void set_inner_loop() { _loop_flags |= inner_loop; } int is_partial_peel_loop() const { return _loop_flags & partial_peel_loop; } void set_partial_peel_loop() { _loop_flags |= partial_peel_loop; } int partial_peel_has_failed() const { return _loop_flags & partial_peel_failed; } void mark_partial_peel_failed() { _loop_flags |= partial_peel_failed; } int unswitch_max() { return _unswitch_max; } int unswitch_count() { return _unswitch_count; } void set_unswitch_count(int val) { assert (val <= unswitch_max(), "too many unswitches"); _unswitch_count = val; } LoopNode( Node *entry, Node *backedge ) : RegionNode(3), _loop_flags(0), _unswitch_count(0) { init_class_id(Class_Loop); init_req(EntryControl, entry); init_req(LoopBackControl, backedge); } virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); virtual int Opcode() const; bool can_be_counted_loop(PhaseTransform* phase) const { return req() == 3 && in(0) != NULL && in(1) != NULL && phase->type(in(1)) != Type::TOP && in(2) != NULL && phase->type(in(2)) != Type::TOP; } #ifndef PRODUCT virtual void dump_spec(outputStream *st) const; #endif }; //------------------------------Counted Loops---------------------------------- // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit // path (and maybe some other exit paths). The trip-counter exit is always // last in the loop. The trip-counter does not have to stride by a constant, // but it does have to stride by a loop-invariant amount; the exit value is // also loop invariant. // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The // CountedLoopNode has the incoming loop control and the loop-back-control // which is always the IfTrue before the matching CountedLoopEndNode. The // CountedLoopEndNode has an incoming control (possibly not the // CountedLoopNode if there is control flow in the loop), the post-increment // trip-counter value, and the limit. The trip-counter value is always of // the form (Op old-trip-counter stride). The old-trip-counter is produced // by a Phi connected to the CountedLoopNode. The stride is loop invariant. // The Op is any commutable opcode, including Add, Mul, Xor. The // CountedLoopEndNode also takes in the loop-invariant limit value. // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes // via the old-trip-counter from the Op node. //------------------------------CountedLoopNode-------------------------------- // CountedLoopNodes head simple counted loops. CountedLoopNodes have as // inputs the incoming loop-start control and the loop-back control, so they // act like RegionNodes. They also take in the initial trip counter, the // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes // produce a loop-body control and the trip counter value. Since // CountedLoopNodes behave like RegionNodes I still have a standard CFG model. class CountedLoopNode : public LoopNode { // Size is bigger to hold _main_idx. However, _main_idx does not change // the semantics so it does not appear in the hash & cmp functions. virtual uint size_of() const { return sizeof(*this); } // For Pre- and Post-loops during debugging ONLY, this holds the index of // the Main CountedLoop. Used to assert that we understand the graph shape. node_idx_t _main_idx; // Known trip count calculated by policy_maximally_unroll int _trip_count; // Expected trip count from profile data float _profile_trip_cnt; // Log2 of original loop bodies in unrolled loop int _unrolled_count_log2; // Node count prior to last unrolling - used to decide if // unroll,optimize,unroll,optimize,... is making progress int _node_count_before_unroll; public: CountedLoopNode( Node *entry, Node *backedge ) : LoopNode(entry, backedge), _trip_count(max_jint), _profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0), _node_count_before_unroll(0) { init_class_id(Class_CountedLoop); // Initialize _trip_count to the largest possible value. // Will be reset (lower) if the loop's trip count is known. } virtual int Opcode() const; virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); Node *init_control() const { return in(EntryControl); } Node *back_control() const { return in(LoopBackControl); } CountedLoopEndNode *loopexit() const; Node *init_trip() const; Node *stride() const; int stride_con() const; bool stride_is_con() const; Node *limit() const; Node *incr() const; Node *phi() const; // Match increment with optional truncation static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type); // A 'main' loop has a pre-loop and a post-loop. The 'main' loop // can run short a few iterations and may start a few iterations in. // It will be RCE'd and unrolled and aligned. // A following 'post' loop will run any remaining iterations. Used // during Range Check Elimination, the 'post' loop will do any final // iterations with full checks. Also used by Loop Unrolling, where // the 'post' loop will do any epilog iterations needed. Basically, // a 'post' loop can not profitably be further unrolled or RCE'd. // A preceding 'pre' loop will run at least 1 iteration (to do peeling), // it may do under-flow checks for RCE and may do alignment iterations // so the following main loop 'knows' that it is striding down cache // lines. // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or // Aligned, may be missing it's pre-loop. enum { Normal=0, Pre=1, Main=2, Post=3, PrePostFlagsMask=3, Main_Has_No_Pre_Loop=4 }; int is_normal_loop() const { return (_loop_flags&PrePostFlagsMask) == Normal; } int is_pre_loop () const { return (_loop_flags&PrePostFlagsMask) == Pre; } int is_main_loop () const { return (_loop_flags&PrePostFlagsMask) == Main; } int is_post_loop () const { return (_loop_flags&PrePostFlagsMask) == Post; } int is_main_no_pre_loop() const { return _loop_flags & Main_Has_No_Pre_Loop; } void set_main_no_pre_loop() { _loop_flags |= Main_Has_No_Pre_Loop; } int main_idx() const { return _main_idx; } void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; } void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; } void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; } void set_normal_loop( ) { _loop_flags &= ~PrePostFlagsMask; } void set_trip_count(int tc) { _trip_count = tc; } int trip_count() { return _trip_count; } void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; } float profile_trip_cnt() { return _profile_trip_cnt; } void double_unrolled_count() { _unrolled_count_log2++; } int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); } void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; } int node_count_before_unroll() { return _node_count_before_unroll; } #ifndef PRODUCT virtual void dump_spec(outputStream *st) const; #endif }; //------------------------------CountedLoopEndNode----------------------------- // CountedLoopEndNodes end simple trip counted loops. They act much like // IfNodes. class CountedLoopEndNode : public IfNode { public: enum { TestControl, TestValue }; CountedLoopEndNode( Node *control, Node *test, float prob, float cnt ) : IfNode( control, test, prob, cnt) { init_class_id(Class_CountedLoopEnd); } virtual int Opcode() const; Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; } Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } Node *phi() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } int stride_con() const; bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); } BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; } CountedLoopNode *loopnode() const { Node *ln = phi()->in(0); assert( ln->Opcode() == Op_CountedLoop, "malformed loop" ); return (CountedLoopNode*)ln; } #ifndef PRODUCT virtual void dump_spec(outputStream *st) const; #endif }; inline CountedLoopEndNode *CountedLoopNode::loopexit() const { Node *bc = back_control(); if( bc == NULL ) return NULL; Node *le = bc->in(0); if( le->Opcode() != Op_CountedLoopEnd ) return NULL; return (CountedLoopEndNode*)le; } inline Node *CountedLoopNode::init_trip() const { return loopexit() ? loopexit()->init_trip() : NULL; } inline Node *CountedLoopNode::stride() const { return loopexit() ? loopexit()->stride() : NULL; } inline int CountedLoopNode::stride_con() const { return loopexit() ? loopexit()->stride_con() : 0; } inline bool CountedLoopNode::stride_is_con() const { return loopexit() && loopexit()->stride_is_con(); } inline Node *CountedLoopNode::limit() const { return loopexit() ? loopexit()->limit() : NULL; } inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; } inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; } // -----------------------------IdealLoopTree---------------------------------- class IdealLoopTree : public ResourceObj { public: IdealLoopTree *_parent; // Parent in loop tree IdealLoopTree *_next; // Next sibling in loop tree IdealLoopTree *_child; // First child in loop tree // The head-tail backedge defines the loop. // If tail is NULL then this loop has multiple backedges as part of the // same loop. During cleanup I'll peel off the multiple backedges; merge // them at the loop bottom and flow 1 real backedge into the loop. Node *_head; // Head of loop Node *_tail; // Tail of loop inline Node *tail(); // Handle lazy update of _tail field PhaseIdealLoop* _phase; Node_List _body; // Loop body for inner loops uint8 _nest; // Nesting depth uint8 _irreducible:1, // True if irreducible _has_call:1, // True if has call safepoint _has_sfpt:1, // True if has non-call safepoint _rce_candidate:1; // True if candidate for range check elimination Node_List* _required_safept; // A inner loop cannot delete these safepts; bool _allow_optimizations; // Allow loop optimizations IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail ) : _parent(0), _next(0), _child(0), _head(head), _tail(tail), _phase(phase), _required_safept(NULL), _allow_optimizations(true), _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0) { } // Is 'l' a member of 'this'? int is_member( const IdealLoopTree *l ) const; // Test for nested membership // Set loop nesting depth. Accumulate has_call bits. int set_nest( uint depth ); // Split out multiple fall-in edges from the loop header. Move them to a // private RegionNode before the loop. This becomes the loop landing pad. void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ); // Split out the outermost loop from this shared header. void split_outer_loop( PhaseIdealLoop *phase ); // Merge all the backedges from the shared header into a private Region. // Feed that region as the one backedge to this loop. void merge_many_backedges( PhaseIdealLoop *phase ); // Split shared headers and insert loop landing pads. // Insert a LoopNode to replace the RegionNode. // Returns TRUE if loop tree is structurally changed. bool beautify_loops( PhaseIdealLoop *phase ); // Perform optimization to use the loop predicates for null checks and range checks. // Applies to any loop level (not just the innermost one) bool loop_predication( PhaseIdealLoop *phase); // Perform iteration-splitting on inner loops. Split iterations to // avoid range checks or one-shot null checks. Returns false if the // current round of loop opts should stop. bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new ); // Driver for various flavors of iteration splitting. Returns false // if the current round of loop opts should stop. bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ); // Given dominators, try to find loops with calls that must always be // executed (call dominates loop tail). These loops do not need non-call // safepoints (ncsfpt). void check_safepts(VectorSet &visited, Node_List &stack); // Allpaths backwards scan from loop tail, terminating each path at first safepoint // encountered. void allpaths_check_safepts(VectorSet &visited, Node_List &stack); // Convert to counted loops where possible void counted_loop( PhaseIdealLoop *phase ); // Check for Node being a loop-breaking test Node *is_loop_exit(Node *iff) const; // Returns true if ctrl is executed on every complete iteration bool dominates_backedge(Node* ctrl); // Remove simplistic dead code from loop body void DCE_loop_body(); // Look for loop-exit tests with my 50/50 guesses from the Parsing stage. // Replace with a 1-in-10 exit guess. void adjust_loop_exit_prob( PhaseIdealLoop *phase ); // Return TRUE or FALSE if the loop should never be RCE'd or aligned. // Useful for unrolling loops with NO array accesses. bool policy_peel_only( PhaseIdealLoop *phase ) const; // Return TRUE or FALSE if the loop should be unswitched -- clone // loop with an invariant test bool policy_unswitching( PhaseIdealLoop *phase ) const; // Micro-benchmark spamming. Remove empty loops. bool policy_do_remove_empty_loop( PhaseIdealLoop *phase ); // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can // make some loop-invariant test (usually a null-check) happen before the // loop. bool policy_peeling( PhaseIdealLoop *phase ) const; // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any // known trip count in the counted loop node. bool policy_maximally_unroll( PhaseIdealLoop *phase ) const; // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if // the loop is a CountedLoop and the body is small enough. bool policy_unroll( PhaseIdealLoop *phase ) const; // Return TRUE or FALSE if the loop should be range-check-eliminated. // Gather a list of IF tests that are dominated by iteration splitting; // also gather the end of the first split and the start of the 2nd split. bool policy_range_check( PhaseIdealLoop *phase ) const; // Return TRUE or FALSE if the loop should be cache-line aligned. // Gather the expression that does the alignment. Note that only // one array base can be aligned in a loop (unless the VM guarantees // mutual alignment). Note that if we vectorize short memory ops // into longer memory ops, we may want to increase alignment. bool policy_align( PhaseIdealLoop *phase ) const; // Return TRUE if "iff" is a range check. bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const; // Compute loop trip count from profile data void compute_profile_trip_cnt( PhaseIdealLoop *phase ); // Reassociate invariant expressions. void reassociate_invariants(PhaseIdealLoop *phase); // Reassociate invariant add and subtract expressions. Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase); // Return nonzero index of invariant operand if invariant and variant // are combined with an Add or Sub. Helper for reassociate_invariants. int is_invariant_addition(Node* n, PhaseIdealLoop *phase); // Return true if n is invariant bool is_invariant(Node* n) const; // Put loop body on igvn work list void record_for_igvn(); bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); } bool is_inner() { return is_loop() && _child == NULL; } bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); } #ifndef PRODUCT void dump_head( ) const; // Dump loop head only void dump() const; // Dump this loop recursively void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const; #endif }; // -----------------------------PhaseIdealLoop--------------------------------- // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees into a // loop tree. Drives the loop-based transformations on the ideal graph. class PhaseIdealLoop : public PhaseTransform { friend class IdealLoopTree; friend class SuperWord; // Pre-computed def-use info PhaseIterGVN &_igvn; // Head of loop tree IdealLoopTree *_ltree_root; // Array of pre-order numbers, plus post-visited bit. // ZERO for not pre-visited. EVEN for pre-visited but not post-visited. // ODD for post-visited. Other bits are the pre-order number. uint *_preorders; uint _max_preorder; const PhaseIdealLoop* _verify_me; bool _verify_only; // Allocate _preorders[] array void allocate_preorders() { _max_preorder = C->unique()+8; _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder); memset(_preorders, 0, sizeof(uint) * _max_preorder); } // Allocate _preorders[] array void reallocate_preorders() { if ( _max_preorder < C->unique() ) { _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique()); _max_preorder = C->unique(); } memset(_preorders, 0, sizeof(uint) * _max_preorder); } // Check to grow _preorders[] array for the case when build_loop_tree_impl() // adds new nodes. void check_grow_preorders( ) { if ( _max_preorder < C->unique() ) { uint newsize = _max_preorder<<1; // double size of array _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize); memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder)); _max_preorder = newsize; } } // Check for pre-visited. Zero for NOT visited; non-zero for visited. int is_visited( Node *n ) const { return _preorders[n->_idx]; } // Pre-order numbers are written to the Nodes array as low-bit-set values. void set_preorder_visited( Node *n, int pre_order ) { assert( !is_visited( n ), "already set" ); _preorders[n->_idx] = (pre_order<<1); }; // Return pre-order number. int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; } // Check for being post-visited. // Should be previsited already (checked with assert(is_visited(n))). int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; } // Mark as post visited void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; } // Set/get control node out. Set lower bit to distinguish from IdealLoopTree // Returns true if "n" is a data node, false if it's a control node. bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; } // clear out dead code after build_loop_late Node_List _deadlist; // Support for faster execution of get_late_ctrl()/dom_lca() // when a node has many uses and dominator depth is deep. Node_Array _dom_lca_tags; void init_dom_lca_tags(); void clear_dom_lca_tags(); // Helper for debugging bad dominance relationships bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early); Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false); // Inline wrapper for frequent cases: // 1) only one use // 2) a use is the same as the current LCA passed as 'n1' Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) { assert( n->is_CFG(), "" ); // Fast-path NULL lca if( lca != NULL && lca != n ) { assert( lca->is_CFG(), "" ); // find LCA of all uses n = dom_lca_for_get_late_ctrl_internal( lca, n, tag ); } return find_non_split_ctrl(n); } Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag ); // Helper function for directing control inputs away from CFG split // points. Node *find_non_split_ctrl( Node *ctrl ) const { if (ctrl != NULL) { if (ctrl->is_MultiBranch()) { ctrl = ctrl->in(0); } assert(ctrl->is_CFG(), "CFG"); } return ctrl; } public: bool has_node( Node* n ) const { return _nodes[n->_idx] != NULL; } // check if transform created new nodes that need _ctrl recorded Node *get_late_ctrl( Node *n, Node *early ); Node *get_early_ctrl( Node *n ); void set_early_ctrl( Node *n ); void set_subtree_ctrl( Node *root ); void set_ctrl( Node *n, Node *ctrl ) { assert( !has_node(n) || has_ctrl(n), "" ); assert( ctrl->in(0), "cannot set dead control node" ); assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" ); _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) ); } // Set control and update loop membership void set_ctrl_and_loop(Node* n, Node* ctrl) { IdealLoopTree* old_loop = get_loop(get_ctrl(n)); IdealLoopTree* new_loop = get_loop(ctrl); if (old_loop != new_loop) { if (old_loop->_child == NULL) old_loop->_body.yank(n); if (new_loop->_child == NULL) new_loop->_body.push(n); } set_ctrl(n, ctrl); } // Control nodes can be replaced or subsumed. During this pass they // get their replacement Node in slot 1. Instead of updating the block // location of all Nodes in the subsumed block, we lazily do it. As we // pull such a subsumed block out of the array, we write back the final // correct block. Node *get_ctrl( Node *i ) { assert(has_node(i), ""); Node *n = get_ctrl_no_update(i); _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) ); assert(has_node(i) && has_ctrl(i), ""); assert(n == find_non_split_ctrl(n), "must return legal ctrl" ); return n; } // true if CFG node d dominates CFG node n bool is_dominator(Node *d, Node *n); // return get_ctrl for a data node and self(n) for a CFG node Node* ctrl_or_self(Node* n) { if (has_ctrl(n)) return get_ctrl(n); else { assert (n->is_CFG(), "must be a CFG node"); return n; } } private: Node *get_ctrl_no_update( Node *i ) const { assert( has_ctrl(i), "" ); Node *n = (Node*)(((intptr_t)_nodes[i->_idx]) & ~1); if (!n->in(0)) { // Skip dead CFG nodes do { n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); } while (!n->in(0)); n = find_non_split_ctrl(n); } return n; } // Check for loop being set // "n" must be a control node. Returns true if "n" is known to be in a loop. bool has_loop( Node *n ) const { assert(!has_node(n) || !has_ctrl(n), ""); return has_node(n); } // Set loop void set_loop( Node *n, IdealLoopTree *loop ) { _nodes.map(n->_idx, (Node*)loop); } // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace // the 'old_node' with 'new_node'. Kill old-node. Add a reference // from old_node to new_node to support the lazy update. Reference // replaces loop reference, since that is not needed for dead node. public: void lazy_update( Node *old_node, Node *new_node ) { assert( old_node != new_node, "no cycles please" ); //old_node->set_req( 1, new_node /*NO DU INFO*/ ); // Nodes always have DU info now, so re-use the side array slot // for this node to provide the forwarding pointer. _nodes.map( old_node->_idx, (Node*)((intptr_t)new_node + 1) ); } void lazy_replace( Node *old_node, Node *new_node ) { _igvn.hash_delete(old_node); _igvn.subsume_node( old_node, new_node ); lazy_update( old_node, new_node ); } void lazy_replace_proj( Node *old_node, Node *new_node ) { assert( old_node->req() == 1, "use this for Projs" ); _igvn.hash_delete(old_node); // Must hash-delete before hacking edges old_node->add_req( NULL ); lazy_replace( old_node, new_node ); } private: // Place 'n' in some loop nest, where 'n' is a CFG node void build_loop_tree(); int build_loop_tree_impl( Node *n, int pre_order ); // Insert loop into the existing loop tree. 'innermost' is a leaf of the // loop tree, not the root. IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost ); // Place Data nodes in some loop nest void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); void build_loop_late_post ( Node* n ); // Array of immediate dominance info for each CFG node indexed by node idx private: uint _idom_size; Node **_idom; // Array of immediate dominators uint *_dom_depth; // Used for fast LCA test GrowableArray* _dom_stk; // For recomputation of dom depth Node* idom_no_update(Node* d) const { assert(d->_idx < _idom_size, "oob"); Node* n = _idom[d->_idx]; assert(n != NULL,"Bad immediate dominator info."); while (n->in(0) == NULL) { // Skip dead CFG nodes //n = n->in(1); n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); assert(n != NULL,"Bad immediate dominator info."); } return n; } Node *idom(Node* d) const { uint didx = d->_idx; Node *n = idom_no_update(d); _idom[didx] = n; // Lazily remove dead CFG nodes from table. return n; } uint dom_depth(Node* d) const { assert(d->_idx < _idom_size, ""); return _dom_depth[d->_idx]; } void set_idom(Node* d, Node* n, uint dom_depth); // Locally compute IDOM using dom_lca call Node *compute_idom( Node *region ) const; // Recompute dom_depth void recompute_dom_depth(); // Is safept not required by an outer loop? bool is_deleteable_safept(Node* sfpt); // Perform verification that the graph is valid. PhaseIdealLoop( PhaseIterGVN &igvn) : PhaseTransform(Ideal_Loop), _igvn(igvn), _dom_lca_tags(C->comp_arena()), _verify_me(NULL), _verify_only(true) { build_and_optimize(false, false); } // build the loop tree and perform any requested optimizations void build_and_optimize(bool do_split_if, bool do_loop_pred); public: // Dominators for the sea of nodes void Dominators(); Node *dom_lca( Node *n1, Node *n2 ) const { return find_non_split_ctrl(dom_lca_internal(n1, n2)); } Node *dom_lca_internal( Node *n1, Node *n2 ) const; // Compute the Ideal Node to Loop mapping PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool do_loop_pred) : PhaseTransform(Ideal_Loop), _igvn(igvn), _dom_lca_tags(C->comp_arena()), _verify_me(NULL), _verify_only(false) { build_and_optimize(do_split_ifs, do_loop_pred); } // Verify that verify_me made the same decisions as a fresh run. PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) : PhaseTransform(Ideal_Loop), _igvn(igvn), _dom_lca_tags(C->comp_arena()), _verify_me(verify_me), _verify_only(false) { build_and_optimize(false, false); } // Build and verify the loop tree without modifying the graph. This // is useful to verify that all inputs properly dominate their uses. static void verify(PhaseIterGVN& igvn) { #ifdef ASSERT PhaseIdealLoop v(igvn); #endif } // True if the method has at least 1 irreducible loop bool _has_irreducible_loops; // Per-Node transform virtual Node *transform( Node *a_node ) { return 0; } Node *is_counted_loop( Node *x, IdealLoopTree *loop ); // Return a post-walked LoopNode IdealLoopTree *get_loop( Node *n ) const { // Dead nodes have no loop, so return the top level loop instead if (!has_node(n)) return _ltree_root; assert(!has_ctrl(n), ""); return (IdealLoopTree*)_nodes[n->_idx]; } // Is 'n' a (nested) member of 'loop'? int is_member( const IdealLoopTree *loop, Node *n ) const { return loop->is_member(get_loop(n)); } // 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. // Parameter side_by_side_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 passed in side_by_side_idom node. Used in // construction of unswitched loops. void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth, Node* side_by_side_idom = NULL); // If we got the effect of peeling, either by actually peeling or by // making a pre-loop which must execute at least once, we can remove // all loop-invariant dominated tests in the main body. void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ); // Generate code to do a loop peel for the given loop (and body). // old_new is a temp array. void do_peeling( IdealLoopTree *loop, Node_List &old_new ); // Add pre and post loops around the given loop. These loops are used // during RCE, unrolling and aligning loops. void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ); // If Node n lives in the back_ctrl block, we clone a private version of n // in preheader_ctrl block and return that, otherwise return n. Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n ); // Take steps to maximally unroll the loop. Peel any odd iterations, then // unroll to do double iterations. The next round of major loop transforms // will repeat till the doubled loop body does all remaining iterations in 1 // pass. void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ); // Unroll the loop body one step - make each trip do 2 iterations. void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ); // Return true if exp is a constant times an induction var bool is_scaled_iv(Node* exp, Node* iv, int* p_scale); // Return true if exp is a scaled induction var plus (or minus) constant bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0); // Return true if proj is for "proj->[region->..]call_uct" bool is_uncommon_trap_proj(ProjNode* proj, bool must_reason_predicate = false); // Return true for "if(test)-> proj -> ... // | // V // other_proj->[region->..]call_uct" bool is_uncommon_trap_if_pattern(ProjNode* proj, bool must_reason_predicate = false); // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted ProjNode* create_new_if_for_predicate(ProjNode* cont_proj); // Find a good location to insert a predicate ProjNode* find_predicate_insertion_point(Node* start_c); // Construct a range check for a predicate if BoolNode* rc_predicate(Node* ctrl, int scale, Node* offset, Node* init, Node* limit, Node* stride, Node* range); // Implementation of the loop predication to promote checks outside the loop bool loop_predication_impl(IdealLoopTree *loop); // Helper function to collect predicate for eliminating the useless ones void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1); void eliminate_useless_predicates(); // Eliminate range-checks and other trip-counter vs loop-invariant tests. void do_range_check( IdealLoopTree *loop, Node_List &old_new ); // Create a slow version of the loop by cloning the loop // and inserting an if to select fast-slow versions. ProjNode* create_slow_version_of_loop(IdealLoopTree *loop, Node_List &old_new); // Clone loop with an invariant test (that does not exit) and // insert a clone of the test that selects which version to // execute. void do_unswitching (IdealLoopTree *loop, Node_List &old_new); // Find candidate "if" for unswitching IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const; // Range Check Elimination uses this function! // Constrain the main loop iterations so the affine function: // scale_con * I + offset < limit // always holds true. That is, either increase the number of iterations in // the pre-loop or the post-loop until the condition holds true in the main // loop. Scale_con, offset and limit are all loop invariant. void add_constraint( int stride_con, int scale_con, Node *offset, Node *limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit ); // Partially peel loop up through last_peel node. bool partial_peel( IdealLoopTree *loop, Node_List &old_new ); // Create a scheduled list of nodes control dependent on ctrl set. void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched ); // Has a use in the vector set bool has_use_in_set( Node* n, VectorSet& vset ); // Has use internal to the vector set (ie. not in a phi at the loop head) bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ); // clone "n" for uses that are outside of loop void clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ); // clone "n" for special uses that are in the not_peeled region void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n, VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ); // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ); #ifdef ASSERT // Validate the loop partition sets: peel and not_peel bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel ); // Ensure that uses outside of loop are of the right form bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list, uint orig_exit_idx, uint clone_exit_idx); bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx); #endif // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.) int stride_of_possible_iv( Node* iff ); bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; } // Return the (unique) control output node that's in the loop (if it exists.) Node* stay_in_loop( Node* n, IdealLoopTree *loop); // Insert a signed compare loop exit cloned from an unsigned compare. IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop); void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop); // Utility to register node "n" with PhaseIdealLoop void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth); // Utility to create an if-projection ProjNode* proj_clone(ProjNode* p, IfNode* iff); // Force the iff control output to be the live_proj Node* short_circuit_if(IfNode* iff, ProjNode* live_proj); // Insert a region before an if projection RegionNode* insert_region_before_proj(ProjNode* proj); // Insert a new if before an if projection ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj); // 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 *clone_iff( PhiNode *phi, IdealLoopTree *loop ); CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop ); // 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 *remix_address_expressions( Node *n ); // Attempt to use a conditional move instead of a phi/branch Node *conditional_move( Node *n ); // 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 reorg_offsets( IdealLoopTree *loop ); // Check for aggressive application of 'split-if' optimization, // using basic block level info. void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack ); Node *split_if_with_blocks_pre ( Node *n ); void split_if_with_blocks_post( Node *n ); Node *has_local_phi_input( Node *n ); // Mark an IfNode as being dominated by a prior test, // without actually altering the CFG (and hence IDOM info). void dominated_by( Node *prevdom, Node *iff ); // Split Node 'n' through merge point Node *split_thru_region( Node *n, Node *region ); // Split Node 'n' through merge point if there is enough win. Node *split_thru_phi( Node *n, Node *region, int policy ); // Found an If getting its condition-code input from a Phi in the // same block. Split thru the Region. void do_split_if( Node *iff ); private: // Return a type based on condition control flow const TypeInt* filtered_type( Node *n, Node* n_ctrl); const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); } // Helpers for filtered type const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl); // Helper functions Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache ); Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ); void handle_use( Node *use, Node *def, small_cache *cache, Node *region_dom, Node *new_false, Node *new_true, Node *old_false, Node *old_true ); bool split_up( Node *n, Node *blk1, Node *blk2 ); void sink_use( Node *use, Node *post_loop ); Node *place_near_use( Node *useblock ) const; bool _created_loop_node; public: void set_created_loop_node() { _created_loop_node = true; } bool created_loop_node() { return _created_loop_node; } void register_new_node( Node *n, Node *blk ); #ifndef PRODUCT void dump( ) const; void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const; void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const; void verify() const; // Major slow :-) void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const; IdealLoopTree *get_loop_idx(Node* n) const { // Dead nodes have no loop, so return the top level loop instead return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root; } // Print some stats static void print_statistics(); static int _loop_invokes; // Count of PhaseIdealLoop invokes static int _loop_work; // Sum of PhaseIdealLoop x _unique #endif }; inline Node* IdealLoopTree::tail() { // Handle lazy update of _tail field Node *n = _tail; //while( !n->in(0) ) // Skip dead CFG nodes //n = n->in(1); if (n->in(0) == NULL) n = _phase->get_ctrl(n); _tail = n; return n; } // Iterate over the loop tree using a preorder, left-to-right traversal. // // Example that visits all counted loops from within PhaseIdealLoop // // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { // IdealLoopTree* lpt = iter.current(); // if (!lpt->is_counted()) continue; // ... class LoopTreeIterator : public StackObj { private: IdealLoopTree* _root; IdealLoopTree* _curnt; public: LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {} bool done() { return _curnt == NULL; } // Finished iterating? void next(); // Advance to next loop tree IdealLoopTree* current() { return _curnt; } // Return current value of iterator. };