--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/opto/loopnode.hpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,919 @@
+/*
+ * Copyright 1998-2007 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;
+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; }
+
+
+ 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;
+
+ IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
+ : _parent(0), _next(0), _child(0),
+ _head(head), _tail(tail),
+ _phase(phase),
+ _required_safept(NULL),
+ _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 iteration-splitting on inner loops. Split iterations to avoid
+ // range checks or one-shot null checks.
+ void iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
+
+ // Driver for various flavors of iteration splitting
+ void 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 guarentees
+ // 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;
+
+ // 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 reassoicate_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;
+
+ // 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();
+ // 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 );
+ // true if CFG node d dominates CFG node n
+ bool is_dominator(Node *d, Node *n);
+
+ // 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;
+ }
+
+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 neede 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, const PhaseIdealLoop *verify_me );
+ void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack, const PhaseIdealLoop *verify_me );
+ void build_loop_late_post ( Node* n, const PhaseIdealLoop *verify_me );
+
+ // 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<uint>* _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);
+
+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, const PhaseIdealLoop *verify_me, bool do_split_ifs );
+
+ // 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);
+
+ // 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);
+ const TypeInt* filtered_type_at_if( Node* val, Node *if_proj);
+
+ // Helper functions
+ void register_new_node( Node *n, Node *blk );
+ 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; }
+
+#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.
+};