truffle: src/share/vm/opto/loopnode.hpp comparison

comparison src/share/vm/opto/loopnode.hpp @ 0:a61af66fc99e jdk7-b24

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author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
parents
children	ff5961f4c095

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+:a61af66fc99e
+/*
+* 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.
+};

Mercurial > hg > truffle

comparison src/share/vm/opto/loopnode.hpp @ 0:a61af66fc99e jdk7-b24