hotspot/src/share/vm/opto/loopnode.hpp
author cfang
Tue, 12 Jan 2010 14:37:35 -0800
changeset 4643 61c659c91c57
parent 3676 3bac3e882cd3
child 5054 6d42dc4dd98c
permissions -rw-r--r--
6894779: Loop Predication for Loop Optimizer in C2 Summary: Loop predication implementation Reviewed-by: never, kvn
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/*
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 * Copyright 1998-2009 Sun Microsystems, Inc.  All Rights Reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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 * CA 95054 USA or visit www.sun.com if you need additional information or
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 * have any questions.
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 *
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 */
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class CmpNode;
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class CountedLoopEndNode;
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class CountedLoopNode;
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class IdealLoopTree;
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class LoopNode;
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class Node;
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class PhaseIdealLoop;
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class VectorSet;
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class Invariance;
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struct small_cache;
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//
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//                  I D E A L I Z E D   L O O P S
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//
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// Idealized loops are the set of loops I perform more interesting
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// transformations on, beyond simple hoisting.
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//------------------------------LoopNode---------------------------------------
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// Simple loop header.  Fall in path on left, loop-back path on right.
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class LoopNode : public RegionNode {
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  // Size is bigger to hold the flags.  However, the flags do not change
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  // the semantics so it does not appear in the hash & cmp functions.
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  virtual uint size_of() const { return sizeof(*this); }
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protected:
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  short _loop_flags;
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  // Names for flag bitfields
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  enum { pre_post_main=0, inner_loop=8, partial_peel_loop=16, partial_peel_failed=32  };
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  char _unswitch_count;
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  enum { _unswitch_max=3 };
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public:
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  // Names for edge indices
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  enum { Self=0, EntryControl, LoopBackControl };
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  int is_inner_loop() const { return _loop_flags & inner_loop; }
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  void set_inner_loop() { _loop_flags |= inner_loop; }
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  int is_partial_peel_loop() const { return _loop_flags & partial_peel_loop; }
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  void set_partial_peel_loop() { _loop_flags |= partial_peel_loop; }
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  int partial_peel_has_failed() const { return _loop_flags & partial_peel_failed; }
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  void mark_partial_peel_failed() { _loop_flags |= partial_peel_failed; }
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  int unswitch_max() { return _unswitch_max; }
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  int unswitch_count() { return _unswitch_count; }
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  void set_unswitch_count(int val) {
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    assert (val <= unswitch_max(), "too many unswitches");
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    _unswitch_count = val;
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  }
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  LoopNode( Node *entry, Node *backedge ) : RegionNode(3), _loop_flags(0), _unswitch_count(0) {
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    init_class_id(Class_Loop);
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    init_req(EntryControl, entry);
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    init_req(LoopBackControl, backedge);
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  }
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  virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
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  virtual int Opcode() const;
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  bool can_be_counted_loop(PhaseTransform* phase) const {
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    return req() == 3 && in(0) != NULL &&
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      in(1) != NULL && phase->type(in(1)) != Type::TOP &&
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      in(2) != NULL && phase->type(in(2)) != Type::TOP;
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  }
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#ifndef PRODUCT
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  virtual void dump_spec(outputStream *st) const;
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#endif
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};
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//------------------------------Counted Loops----------------------------------
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// Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
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// path (and maybe some other exit paths).  The trip-counter exit is always
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// last in the loop.  The trip-counter does not have to stride by a constant,
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// but it does have to stride by a loop-invariant amount; the exit value is
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// also loop invariant.
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// CountedLoopNodes and CountedLoopEndNodes come in matched pairs.  The
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// CountedLoopNode has the incoming loop control and the loop-back-control
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// which is always the IfTrue before the matching CountedLoopEndNode.  The
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// CountedLoopEndNode has an incoming control (possibly not the
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// CountedLoopNode if there is control flow in the loop), the post-increment
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// trip-counter value, and the limit.  The trip-counter value is always of
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// the form (Op old-trip-counter stride).  The old-trip-counter is produced
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// by a Phi connected to the CountedLoopNode.  The stride is loop invariant.
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// The Op is any commutable opcode, including Add, Mul, Xor.  The
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// CountedLoopEndNode also takes in the loop-invariant limit value.
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// From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
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// loop-back control.  From CountedLoopEndNodes I can reach CountedLoopNodes
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// via the old-trip-counter from the Op node.
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//------------------------------CountedLoopNode--------------------------------
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// CountedLoopNodes head simple counted loops.  CountedLoopNodes have as
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// inputs the incoming loop-start control and the loop-back control, so they
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// act like RegionNodes.  They also take in the initial trip counter, the
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// loop-invariant stride and the loop-invariant limit value.  CountedLoopNodes
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// produce a loop-body control and the trip counter value.  Since
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// CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
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class CountedLoopNode : public LoopNode {
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  // Size is bigger to hold _main_idx.  However, _main_idx does not change
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  // the semantics so it does not appear in the hash & cmp functions.
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  virtual uint size_of() const { return sizeof(*this); }
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  // For Pre- and Post-loops during debugging ONLY, this holds the index of
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  // the Main CountedLoop.  Used to assert that we understand the graph shape.
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  node_idx_t _main_idx;
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  // Known trip count calculated by policy_maximally_unroll
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  int   _trip_count;
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  // Expected trip count from profile data
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  float _profile_trip_cnt;
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  // Log2 of original loop bodies in unrolled loop
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  int _unrolled_count_log2;
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  // Node count prior to last unrolling - used to decide if
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  // unroll,optimize,unroll,optimize,... is making progress
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  int _node_count_before_unroll;
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public:
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  CountedLoopNode( Node *entry, Node *backedge )
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    : LoopNode(entry, backedge), _trip_count(max_jint),
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      _profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0),
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      _node_count_before_unroll(0) {
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    init_class_id(Class_CountedLoop);
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    // Initialize _trip_count to the largest possible value.
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    // Will be reset (lower) if the loop's trip count is known.
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  }
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  virtual int Opcode() const;
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  virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
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  Node *init_control() const { return in(EntryControl); }
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  Node *back_control() const { return in(LoopBackControl); }
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  CountedLoopEndNode *loopexit() const;
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  Node *init_trip() const;
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  Node *stride() const;
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  int   stride_con() const;
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  bool  stride_is_con() const;
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  Node *limit() const;
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  Node *incr() const;
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  Node *phi() const;
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  // Match increment with optional truncation
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  static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type);
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  // A 'main' loop has a pre-loop and a post-loop.  The 'main' loop
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  // can run short a few iterations and may start a few iterations in.
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  // It will be RCE'd and unrolled and aligned.
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  // A following 'post' loop will run any remaining iterations.  Used
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  // during Range Check Elimination, the 'post' loop will do any final
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  // iterations with full checks.  Also used by Loop Unrolling, where
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  // the 'post' loop will do any epilog iterations needed.  Basically,
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  // a 'post' loop can not profitably be further unrolled or RCE'd.
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  // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
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  // it may do under-flow checks for RCE and may do alignment iterations
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  // so the following main loop 'knows' that it is striding down cache
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  // lines.
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  // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
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  // Aligned, may be missing it's pre-loop.
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  enum { Normal=0, Pre=1, Main=2, Post=3, PrePostFlagsMask=3, Main_Has_No_Pre_Loop=4 };
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  int is_normal_loop() const { return (_loop_flags&PrePostFlagsMask) == Normal; }
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  int is_pre_loop   () const { return (_loop_flags&PrePostFlagsMask) == Pre;    }
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  int is_main_loop  () const { return (_loop_flags&PrePostFlagsMask) == Main;   }
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  int is_post_loop  () const { return (_loop_flags&PrePostFlagsMask) == Post;   }
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  int is_main_no_pre_loop() const { return _loop_flags & Main_Has_No_Pre_Loop; }
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  void set_main_no_pre_loop() { _loop_flags |= Main_Has_No_Pre_Loop; }
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  int main_idx() const { return _main_idx; }
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1
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  void set_pre_loop  (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
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  void set_main_loop (                     ) { assert(is_normal_loop(),""); _loop_flags |= Main;                         }
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  void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
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  void set_normal_loop(                    ) { _loop_flags &= ~PrePostFlagsMask; }
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  void set_trip_count(int tc) { _trip_count = tc; }
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  int trip_count()            { return _trip_count; }
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  void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
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  float profile_trip_cnt()             { return _profile_trip_cnt; }
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  void double_unrolled_count() { _unrolled_count_log2++; }
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  int  unrolled_count()        { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
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  void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }
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  int  node_count_before_unroll()           { return _node_count_before_unroll; }
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#ifndef PRODUCT
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  virtual void dump_spec(outputStream *st) const;
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#endif
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};
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//------------------------------CountedLoopEndNode-----------------------------
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// CountedLoopEndNodes end simple trip counted loops.  They act much like
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// IfNodes.
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class CountedLoopEndNode : public IfNode {
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public:
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  enum { TestControl, TestValue };
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  CountedLoopEndNode( Node *control, Node *test, float prob, float cnt )
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    : IfNode( control, test, prob, cnt) {
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    init_class_id(Class_CountedLoopEnd);
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  }
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  virtual int Opcode() const;
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  Node *cmp_node() const            { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; }
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  Node *incr() const                { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }
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  Node *limit() const               { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; }
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  Node *stride() const              { Node *tmp = incr    (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; }
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  Node *phi() const                 { Node *tmp = incr    (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }
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  Node *init_trip() const           { Node *tmp = phi     (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }
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  int stride_con() const;
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  bool stride_is_con() const        { Node *tmp = stride  (); return (tmp != NULL && tmp->is_Con()); }
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  BoolTest::mask test_trip() const  { return in(TestValue)->as_Bool()->_test._test; }
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  CountedLoopNode *loopnode() const {
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    Node *ln = phi()->in(0);
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    assert( ln->Opcode() == Op_CountedLoop, "malformed loop" );
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    return (CountedLoopNode*)ln; }
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#ifndef PRODUCT
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  virtual void dump_spec(outputStream *st) const;
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#endif
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};
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inline CountedLoopEndNode *CountedLoopNode::loopexit() const {
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  Node *bc = back_control();
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  if( bc == NULL ) return NULL;
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  Node *le = bc->in(0);
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  if( le->Opcode() != Op_CountedLoopEnd )
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    return NULL;
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  return (CountedLoopEndNode*)le;
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}
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inline Node *CountedLoopNode::init_trip() const { return loopexit() ? loopexit()->init_trip() : NULL; }
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inline Node *CountedLoopNode::stride() const { return loopexit() ? loopexit()->stride() : NULL; }
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inline int CountedLoopNode::stride_con() const { return loopexit() ? loopexit()->stride_con() : 0; }
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inline bool CountedLoopNode::stride_is_con() const { return loopexit() && loopexit()->stride_is_con(); }
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inline Node *CountedLoopNode::limit() const { return loopexit() ? loopexit()->limit() : NULL; }
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inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; }
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inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; }
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// -----------------------------IdealLoopTree----------------------------------
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class IdealLoopTree : public ResourceObj {
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public:
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  IdealLoopTree *_parent;       // Parent in loop tree
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  IdealLoopTree *_next;         // Next sibling in loop tree
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  IdealLoopTree *_child;        // First child in loop tree
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  // The head-tail backedge defines the loop.
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  // If tail is NULL then this loop has multiple backedges as part of the
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  // same loop.  During cleanup I'll peel off the multiple backedges; merge
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  // them at the loop bottom and flow 1 real backedge into the loop.
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  Node *_head;                  // Head of loop
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  Node *_tail;                  // Tail of loop
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  inline Node *tail();          // Handle lazy update of _tail field
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  PhaseIdealLoop* _phase;
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  Node_List _body;              // Loop body for inner loops
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  uint8 _nest;                  // Nesting depth
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  uint8 _irreducible:1,         // True if irreducible
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        _has_call:1,            // True if has call safepoint
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        _has_sfpt:1,            // True if has non-call safepoint
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        _rce_candidate:1;       // True if candidate for range check elimination
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  Node_List* _required_safept;  // A inner loop cannot delete these safepts;
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  bool  _allow_optimizations;   // Allow loop optimizations
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  IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
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    : _parent(0), _next(0), _child(0),
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      _head(head), _tail(tail),
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      _phase(phase),
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      _required_safept(NULL),
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      _allow_optimizations(true),
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      _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0)
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  { }
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  // Is 'l' a member of 'this'?
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  int is_member( const IdealLoopTree *l ) const; // Test for nested membership
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  // Set loop nesting depth.  Accumulate has_call bits.
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  int set_nest( uint depth );
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  // Split out multiple fall-in edges from the loop header.  Move them to a
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  // private RegionNode before the loop.  This becomes the loop landing pad.
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  void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
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  // Split out the outermost loop from this shared header.
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  void split_outer_loop( PhaseIdealLoop *phase );
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  // Merge all the backedges from the shared header into a private Region.
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  // Feed that region as the one backedge to this loop.
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  void merge_many_backedges( PhaseIdealLoop *phase );
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  // Split shared headers and insert loop landing pads.
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  // Insert a LoopNode to replace the RegionNode.
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  // Returns TRUE if loop tree is structurally changed.
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  bool beautify_loops( PhaseIdealLoop *phase );
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  // Perform optimization to use the loop predicates for null checks and range checks.
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  // Applies to any loop level (not just the innermost one)
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  bool loop_predication( PhaseIdealLoop *phase);
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  // Perform iteration-splitting on inner loops.  Split iterations to
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  // avoid range checks or one-shot null checks.  Returns false if the
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  // current round of loop opts should stop.
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  bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
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  // Driver for various flavors of iteration splitting.  Returns false
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  // if the current round of loop opts should stop.
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  bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
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  // Given dominators, try to find loops with calls that must always be
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  // executed (call dominates loop tail).  These loops do not need non-call
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  // safepoints (ncsfpt).
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  void check_safepts(VectorSet &visited, Node_List &stack);
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  // Allpaths backwards scan from loop tail, terminating each path at first safepoint
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  // encountered.
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  void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
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  // Convert to counted loops where possible
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  void counted_loop( PhaseIdealLoop *phase );
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  // Check for Node being a loop-breaking test
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  Node *is_loop_exit(Node *iff) const;
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  // Returns true if ctrl is executed on every complete iteration
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  bool dominates_backedge(Node* ctrl);
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  // Remove simplistic dead code from loop body
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  void DCE_loop_body();
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  // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
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  // Replace with a 1-in-10 exit guess.
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  void adjust_loop_exit_prob( PhaseIdealLoop *phase );
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  // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
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  // Useful for unrolling loops with NO array accesses.
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  bool policy_peel_only( PhaseIdealLoop *phase ) const;
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parents:
diff changeset
   370
489c9b5090e2 Initial load
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parents:
diff changeset
   371
  // Return TRUE or FALSE if the loop should be unswitched -- clone
489c9b5090e2 Initial load
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parents:
diff changeset
   372
  // loop with an invariant test
489c9b5090e2 Initial load
duke
parents:
diff changeset
   373
  bool policy_unswitching( PhaseIdealLoop *phase ) const;
489c9b5090e2 Initial load
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parents:
diff changeset
   374
489c9b5090e2 Initial load
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parents:
diff changeset
   375
  // Micro-benchmark spamming.  Remove empty loops.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   376
  bool policy_do_remove_empty_loop( PhaseIdealLoop *phase );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   377
489c9b5090e2 Initial load
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parents:
diff changeset
   378
  // Return TRUE or FALSE if the loop should be peeled or not.  Peel if we can
489c9b5090e2 Initial load
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parents:
diff changeset
   379
  // make some loop-invariant test (usually a null-check) happen before the
489c9b5090e2 Initial load
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parents:
diff changeset
   380
  // loop.
489c9b5090e2 Initial load
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parents:
diff changeset
   381
  bool policy_peeling( PhaseIdealLoop *phase ) const;
489c9b5090e2 Initial load
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parents:
diff changeset
   382
489c9b5090e2 Initial load
duke
parents:
diff changeset
   383
  // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
489c9b5090e2 Initial load
duke
parents:
diff changeset
   384
  // known trip count in the counted loop node.
489c9b5090e2 Initial load
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parents:
diff changeset
   385
  bool policy_maximally_unroll( PhaseIdealLoop *phase ) const;
489c9b5090e2 Initial load
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parents:
diff changeset
   386
489c9b5090e2 Initial load
duke
parents:
diff changeset
   387
  // Return TRUE or FALSE if the loop should be unrolled or not.  Unroll if
489c9b5090e2 Initial load
duke
parents:
diff changeset
   388
  // the loop is a CountedLoop and the body is small enough.
489c9b5090e2 Initial load
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parents:
diff changeset
   389
  bool policy_unroll( PhaseIdealLoop *phase ) const;
489c9b5090e2 Initial load
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parents:
diff changeset
   390
489c9b5090e2 Initial load
duke
parents:
diff changeset
   391
  // Return TRUE or FALSE if the loop should be range-check-eliminated.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   392
  // Gather a list of IF tests that are dominated by iteration splitting;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   393
  // also gather the end of the first split and the start of the 2nd split.
489c9b5090e2 Initial load
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parents:
diff changeset
   394
  bool policy_range_check( PhaseIdealLoop *phase ) const;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   395
489c9b5090e2 Initial load
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parents:
diff changeset
   396
  // Return TRUE or FALSE if the loop should be cache-line aligned.
489c9b5090e2 Initial load
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parents:
diff changeset
   397
  // Gather the expression that does the alignment.  Note that only
2131
98f9cef66a34 6810672: Comment typos
twisti
parents: 1433
diff changeset
   398
  // one array base can be aligned in a loop (unless the VM guarantees
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   399
  // mutual alignment).  Note that if we vectorize short memory ops
489c9b5090e2 Initial load
duke
parents:
diff changeset
   400
  // into longer memory ops, we may want to increase alignment.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   401
  bool policy_align( PhaseIdealLoop *phase ) const;
489c9b5090e2 Initial load
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parents:
diff changeset
   402
4643
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   403
  // Return TRUE if "iff" is a range check.
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   404
  bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const;
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   405
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   406
  // Compute loop trip count from profile data
489c9b5090e2 Initial load
duke
parents:
diff changeset
   407
  void compute_profile_trip_cnt( PhaseIdealLoop *phase );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   408
489c9b5090e2 Initial load
duke
parents:
diff changeset
   409
  // Reassociate invariant expressions.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   410
  void reassociate_invariants(PhaseIdealLoop *phase);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   411
  // Reassociate invariant add and subtract expressions.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   412
  Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   413
  // Return nonzero index of invariant operand if invariant and variant
2131
98f9cef66a34 6810672: Comment typos
twisti
parents: 1433
diff changeset
   414
  // are combined with an Add or Sub. Helper for reassociate_invariants.
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   415
  int is_invariant_addition(Node* n, PhaseIdealLoop *phase);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   416
489c9b5090e2 Initial load
duke
parents:
diff changeset
   417
  // Return true if n is invariant
489c9b5090e2 Initial load
duke
parents:
diff changeset
   418
  bool is_invariant(Node* n) const;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   419
489c9b5090e2 Initial load
duke
parents:
diff changeset
   420
  // Put loop body on igvn work list
489c9b5090e2 Initial load
duke
parents:
diff changeset
   421
  void record_for_igvn();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   422
489c9b5090e2 Initial load
duke
parents:
diff changeset
   423
  bool is_loop()    { return !_irreducible && _tail && !_tail->is_top(); }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   424
  bool is_inner()   { return is_loop() && _child == NULL; }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   425
  bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   426
489c9b5090e2 Initial load
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parents:
diff changeset
   427
#ifndef PRODUCT
489c9b5090e2 Initial load
duke
parents:
diff changeset
   428
  void dump_head( ) const;      // Dump loop head only
489c9b5090e2 Initial load
duke
parents:
diff changeset
   429
  void dump() const;            // Dump this loop recursively
489c9b5090e2 Initial load
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parents:
diff changeset
   430
  void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const;
489c9b5090e2 Initial load
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parents:
diff changeset
   431
#endif
489c9b5090e2 Initial load
duke
parents:
diff changeset
   432
489c9b5090e2 Initial load
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parents:
diff changeset
   433
};
489c9b5090e2 Initial load
duke
parents:
diff changeset
   434
489c9b5090e2 Initial load
duke
parents:
diff changeset
   435
// -----------------------------PhaseIdealLoop---------------------------------
489c9b5090e2 Initial load
duke
parents:
diff changeset
   436
// Computes the mapping from Nodes to IdealLoopTrees.  Organizes IdealLoopTrees into a
489c9b5090e2 Initial load
duke
parents:
diff changeset
   437
// loop tree.  Drives the loop-based transformations on the ideal graph.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   438
class PhaseIdealLoop : public PhaseTransform {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   439
  friend class IdealLoopTree;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   440
  friend class SuperWord;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   441
  // Pre-computed def-use info
489c9b5090e2 Initial load
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parents:
diff changeset
   442
  PhaseIterGVN &_igvn;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   443
489c9b5090e2 Initial load
duke
parents:
diff changeset
   444
  // Head of loop tree
489c9b5090e2 Initial load
duke
parents:
diff changeset
   445
  IdealLoopTree *_ltree_root;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   446
489c9b5090e2 Initial load
duke
parents:
diff changeset
   447
  // Array of pre-order numbers, plus post-visited bit.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   448
  // ZERO for not pre-visited.  EVEN for pre-visited but not post-visited.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   449
  // ODD for post-visited.  Other bits are the pre-order number.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   450
  uint *_preorders;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   451
  uint _max_preorder;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   452
3676
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   453
  const PhaseIdealLoop* _verify_me;
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   454
  bool _verify_only;
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   455
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   456
  // Allocate _preorders[] array
489c9b5090e2 Initial load
duke
parents:
diff changeset
   457
  void allocate_preorders() {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   458
    _max_preorder = C->unique()+8;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   459
    _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   460
    memset(_preorders, 0, sizeof(uint) * _max_preorder);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   461
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   462
489c9b5090e2 Initial load
duke
parents:
diff changeset
   463
  // Allocate _preorders[] array
489c9b5090e2 Initial load
duke
parents:
diff changeset
   464
  void reallocate_preorders() {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   465
    if ( _max_preorder < C->unique() ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   466
      _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
489c9b5090e2 Initial load
duke
parents:
diff changeset
   467
      _max_preorder = C->unique();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   468
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   469
    memset(_preorders, 0, sizeof(uint) * _max_preorder);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   470
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   471
489c9b5090e2 Initial load
duke
parents:
diff changeset
   472
  // Check to grow _preorders[] array for the case when build_loop_tree_impl()
489c9b5090e2 Initial load
duke
parents:
diff changeset
   473
  // adds new nodes.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   474
  void check_grow_preorders( ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   475
    if ( _max_preorder < C->unique() ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   476
      uint newsize = _max_preorder<<1;  // double size of array
489c9b5090e2 Initial load
duke
parents:
diff changeset
   477
      _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   478
      memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
489c9b5090e2 Initial load
duke
parents:
diff changeset
   479
      _max_preorder = newsize;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   480
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   481
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   482
  // Check for pre-visited.  Zero for NOT visited; non-zero for visited.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   483
  int is_visited( Node *n ) const { return _preorders[n->_idx]; }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   484
  // Pre-order numbers are written to the Nodes array as low-bit-set values.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   485
  void set_preorder_visited( Node *n, int pre_order ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   486
    assert( !is_visited( n ), "already set" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   487
    _preorders[n->_idx] = (pre_order<<1);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   488
  };
489c9b5090e2 Initial load
duke
parents:
diff changeset
   489
  // Return pre-order number.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   490
  int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   491
489c9b5090e2 Initial load
duke
parents:
diff changeset
   492
  // Check for being post-visited.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   493
  // Should be previsited already (checked with assert(is_visited(n))).
489c9b5090e2 Initial load
duke
parents:
diff changeset
   494
  int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   495
489c9b5090e2 Initial load
duke
parents:
diff changeset
   496
  // Mark as post visited
489c9b5090e2 Initial load
duke
parents:
diff changeset
   497
  void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   498
489c9b5090e2 Initial load
duke
parents:
diff changeset
   499
  // Set/get control node out.  Set lower bit to distinguish from IdealLoopTree
489c9b5090e2 Initial load
duke
parents:
diff changeset
   500
  // Returns true if "n" is a data node, false if it's a control node.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   501
  bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   502
489c9b5090e2 Initial load
duke
parents:
diff changeset
   503
  // clear out dead code after build_loop_late
489c9b5090e2 Initial load
duke
parents:
diff changeset
   504
  Node_List _deadlist;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   505
489c9b5090e2 Initial load
duke
parents:
diff changeset
   506
  // Support for faster execution of get_late_ctrl()/dom_lca()
489c9b5090e2 Initial load
duke
parents:
diff changeset
   507
  // when a node has many uses and dominator depth is deep.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   508
  Node_Array _dom_lca_tags;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   509
  void   init_dom_lca_tags();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   510
  void   clear_dom_lca_tags();
3676
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   511
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   512
  // Helper for debugging bad dominance relationships
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   513
  bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   514
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   515
  Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   516
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   517
  // Inline wrapper for frequent cases:
489c9b5090e2 Initial load
duke
parents:
diff changeset
   518
  // 1) only one use
489c9b5090e2 Initial load
duke
parents:
diff changeset
   519
  // 2) a use is the same as the current LCA passed as 'n1'
489c9b5090e2 Initial load
duke
parents:
diff changeset
   520
  Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   521
    assert( n->is_CFG(), "" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   522
    // Fast-path NULL lca
489c9b5090e2 Initial load
duke
parents:
diff changeset
   523
    if( lca != NULL && lca != n ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   524
      assert( lca->is_CFG(), "" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   525
      // find LCA of all uses
489c9b5090e2 Initial load
duke
parents:
diff changeset
   526
      n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   527
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   528
    return find_non_split_ctrl(n);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   529
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   530
  Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
3676
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   531
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   532
  // Helper function for directing control inputs away from CFG split
489c9b5090e2 Initial load
duke
parents:
diff changeset
   533
  // points.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   534
  Node *find_non_split_ctrl( Node *ctrl ) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   535
    if (ctrl != NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   536
      if (ctrl->is_MultiBranch()) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   537
        ctrl = ctrl->in(0);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   538
      }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   539
      assert(ctrl->is_CFG(), "CFG");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   540
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   541
    return ctrl;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   542
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   543
489c9b5090e2 Initial load
duke
parents:
diff changeset
   544
public:
489c9b5090e2 Initial load
duke
parents:
diff changeset
   545
  bool has_node( Node* n ) const { return _nodes[n->_idx] != NULL; }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   546
  // check if transform created new nodes that need _ctrl recorded
489c9b5090e2 Initial load
duke
parents:
diff changeset
   547
  Node *get_late_ctrl( Node *n, Node *early );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   548
  Node *get_early_ctrl( Node *n );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   549
  void set_early_ctrl( Node *n );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   550
  void set_subtree_ctrl( Node *root );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   551
  void set_ctrl( Node *n, Node *ctrl ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   552
    assert( !has_node(n) || has_ctrl(n), "" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   553
    assert( ctrl->in(0), "cannot set dead control node" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   554
    assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   555
    _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   556
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   557
  // Set control and update loop membership
489c9b5090e2 Initial load
duke
parents:
diff changeset
   558
  void set_ctrl_and_loop(Node* n, Node* ctrl) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   559
    IdealLoopTree* old_loop = get_loop(get_ctrl(n));
489c9b5090e2 Initial load
duke
parents:
diff changeset
   560
    IdealLoopTree* new_loop = get_loop(ctrl);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   561
    if (old_loop != new_loop) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   562
      if (old_loop->_child == NULL) old_loop->_body.yank(n);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   563
      if (new_loop->_child == NULL) new_loop->_body.push(n);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   564
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   565
    set_ctrl(n, ctrl);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   566
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   567
  // Control nodes can be replaced or subsumed.  During this pass they
489c9b5090e2 Initial load
duke
parents:
diff changeset
   568
  // get their replacement Node in slot 1.  Instead of updating the block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   569
  // location of all Nodes in the subsumed block, we lazily do it.  As we
489c9b5090e2 Initial load
duke
parents:
diff changeset
   570
  // pull such a subsumed block out of the array, we write back the final
489c9b5090e2 Initial load
duke
parents:
diff changeset
   571
  // correct block.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   572
  Node *get_ctrl( Node *i ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   573
    assert(has_node(i), "");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   574
    Node *n = get_ctrl_no_update(i);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   575
    _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   576
    assert(has_node(i) && has_ctrl(i), "");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   577
    assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   578
    return n;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   579
  }
4643
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   580
  // true if CFG node d dominates CFG node n
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   581
  bool is_dominator(Node *d, Node *n);
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   582
  // return get_ctrl for a data node and self(n) for a CFG node
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   583
  Node* ctrl_or_self(Node* n) {
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   584
    if (has_ctrl(n))
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   585
      return get_ctrl(n);
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   586
    else {
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   587
      assert (n->is_CFG(), "must be a CFG node");
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   588
      return n;
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   589
    }
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   590
  }
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   591
489c9b5090e2 Initial load
duke
parents:
diff changeset
   592
private:
489c9b5090e2 Initial load
duke
parents:
diff changeset
   593
  Node *get_ctrl_no_update( Node *i ) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   594
    assert( has_ctrl(i), "" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   595
    Node *n = (Node*)(((intptr_t)_nodes[i->_idx]) & ~1);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   596
    if (!n->in(0)) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   597
      // Skip dead CFG nodes
489c9b5090e2 Initial load
duke
parents:
diff changeset
   598
      do {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   599
        n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   600
      } while (!n->in(0));
489c9b5090e2 Initial load
duke
parents:
diff changeset
   601
      n = find_non_split_ctrl(n);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   602
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   603
    return n;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   604
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   605
489c9b5090e2 Initial load
duke
parents:
diff changeset
   606
  // Check for loop being set
489c9b5090e2 Initial load
duke
parents:
diff changeset
   607
  // "n" must be a control node. Returns true if "n" is known to be in a loop.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   608
  bool has_loop( Node *n ) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   609
    assert(!has_node(n) || !has_ctrl(n), "");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   610
    return has_node(n);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   611
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   612
  // Set loop
489c9b5090e2 Initial load
duke
parents:
diff changeset
   613
  void set_loop( Node *n, IdealLoopTree *loop ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   614
    _nodes.map(n->_idx, (Node*)loop);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   615
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   616
  // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms.  Replace
489c9b5090e2 Initial load
duke
parents:
diff changeset
   617
  // the 'old_node' with 'new_node'.  Kill old-node.  Add a reference
489c9b5090e2 Initial load
duke
parents:
diff changeset
   618
  // from old_node to new_node to support the lazy update.  Reference
4643
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   619
  // replaces loop reference, since that is not needed for dead node.
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   620
public:
489c9b5090e2 Initial load
duke
parents:
diff changeset
   621
  void lazy_update( Node *old_node, Node *new_node ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   622
    assert( old_node != new_node, "no cycles please" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   623
    //old_node->set_req( 1, new_node /*NO DU INFO*/ );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   624
    // Nodes always have DU info now, so re-use the side array slot
489c9b5090e2 Initial load
duke
parents:
diff changeset
   625
    // for this node to provide the forwarding pointer.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   626
    _nodes.map( old_node->_idx, (Node*)((intptr_t)new_node + 1) );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   627
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   628
  void lazy_replace( Node *old_node, Node *new_node ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   629
    _igvn.hash_delete(old_node);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   630
    _igvn.subsume_node( old_node, new_node );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   631
    lazy_update( old_node, new_node );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   632
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   633
  void lazy_replace_proj( Node *old_node, Node *new_node ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   634
    assert( old_node->req() == 1, "use this for Projs" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   635
    _igvn.hash_delete(old_node); // Must hash-delete before hacking edges
489c9b5090e2 Initial load
duke
parents:
diff changeset
   636
    old_node->add_req( NULL );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   637
    lazy_replace( old_node, new_node );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   638
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   639
489c9b5090e2 Initial load
duke
parents:
diff changeset
   640
private:
489c9b5090e2 Initial load
duke
parents:
diff changeset
   641
489c9b5090e2 Initial load
duke
parents:
diff changeset
   642
  // Place 'n' in some loop nest, where 'n' is a CFG node
489c9b5090e2 Initial load
duke
parents:
diff changeset
   643
  void build_loop_tree();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   644
  int build_loop_tree_impl( Node *n, int pre_order );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   645
  // Insert loop into the existing loop tree.  'innermost' is a leaf of the
489c9b5090e2 Initial load
duke
parents:
diff changeset
   646
  // loop tree, not the root.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   647
  IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   648
489c9b5090e2 Initial load
duke
parents:
diff changeset
   649
  // Place Data nodes in some loop nest
3676
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   650
  void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   651
  void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   652
  void build_loop_late_post ( Node* n );
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   653
489c9b5090e2 Initial load
duke
parents:
diff changeset
   654
  // Array of immediate dominance info for each CFG node indexed by node idx
489c9b5090e2 Initial load
duke
parents:
diff changeset
   655
private:
489c9b5090e2 Initial load
duke
parents:
diff changeset
   656
  uint _idom_size;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   657
  Node **_idom;                 // Array of immediate dominators
489c9b5090e2 Initial load
duke
parents:
diff changeset
   658
  uint *_dom_depth;           // Used for fast LCA test
489c9b5090e2 Initial load
duke
parents:
diff changeset
   659
  GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
489c9b5090e2 Initial load
duke
parents:
diff changeset
   660
489c9b5090e2 Initial load
duke
parents:
diff changeset
   661
  Node* idom_no_update(Node* d) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   662
    assert(d->_idx < _idom_size, "oob");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   663
    Node* n = _idom[d->_idx];
489c9b5090e2 Initial load
duke
parents:
diff changeset
   664
    assert(n != NULL,"Bad immediate dominator info.");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   665
    while (n->in(0) == NULL) {  // Skip dead CFG nodes
489c9b5090e2 Initial load
duke
parents:
diff changeset
   666
      //n = n->in(1);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   667
      n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   668
      assert(n != NULL,"Bad immediate dominator info.");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   669
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   670
    return n;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   671
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   672
  Node *idom(Node* d) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   673
    uint didx = d->_idx;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   674
    Node *n = idom_no_update(d);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   675
    _idom[didx] = n;            // Lazily remove dead CFG nodes from table.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   676
    return n;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   677
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   678
  uint dom_depth(Node* d) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   679
    assert(d->_idx < _idom_size, "");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   680
    return _dom_depth[d->_idx];
489c9b5090e2 Initial load
duke
parents:
diff changeset
   681
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   682
  void set_idom(Node* d, Node* n, uint dom_depth);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   683
  // Locally compute IDOM using dom_lca call
489c9b5090e2 Initial load
duke
parents:
diff changeset
   684
  Node *compute_idom( Node *region ) const;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   685
  // Recompute dom_depth
489c9b5090e2 Initial load
duke
parents:
diff changeset
   686
  void recompute_dom_depth();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   687
489c9b5090e2 Initial load
duke
parents:
diff changeset
   688
  // Is safept not required by an outer loop?
489c9b5090e2 Initial load
duke
parents:
diff changeset
   689
  bool is_deleteable_safept(Node* sfpt);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   690
3676
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   691
  // Perform verification that the graph is valid.
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   692
  PhaseIdealLoop( PhaseIterGVN &igvn) :
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   693
    PhaseTransform(Ideal_Loop),
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   694
    _igvn(igvn),
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   695
    _dom_lca_tags(C->comp_arena()),
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   696
    _verify_me(NULL),
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   697
    _verify_only(true) {
4643
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   698
    build_and_optimize(false, false);
3676
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   699
  }
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   700
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   701
  // build the loop tree and perform any requested optimizations
4643
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   702
  void build_and_optimize(bool do_split_if, bool do_loop_pred);
3676
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   703
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   704
public:
489c9b5090e2 Initial load
duke
parents:
diff changeset
   705
  // Dominators for the sea of nodes
489c9b5090e2 Initial load
duke
parents:
diff changeset
   706
  void Dominators();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   707
  Node *dom_lca( Node *n1, Node *n2 ) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   708
    return find_non_split_ctrl(dom_lca_internal(n1, n2));
489c9b5090e2 Initial load
duke
parents:
diff changeset
   709
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   710
  Node *dom_lca_internal( Node *n1, Node *n2 ) const;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   711
489c9b5090e2 Initial load
duke
parents:
diff changeset
   712
  // Compute the Ideal Node to Loop mapping
4643
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   713
  PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool do_loop_pred) :
3676
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   714
    PhaseTransform(Ideal_Loop),
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   715
    _igvn(igvn),
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   716
    _dom_lca_tags(C->comp_arena()),
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   717
    _verify_me(NULL),
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   718
    _verify_only(false) {
4643
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   719
    build_and_optimize(do_split_ifs, do_loop_pred);
3676
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   720
  }
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   721
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   722
  // Verify that verify_me made the same decisions as a fresh run.
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   723
  PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) :
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   724
    PhaseTransform(Ideal_Loop),
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   725
    _igvn(igvn),
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   726
    _dom_lca_tags(C->comp_arena()),
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   727
    _verify_me(verify_me),
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   728
    _verify_only(false) {
4643
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   729
    build_and_optimize(false, false);
3676
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   730
  }
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   731
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   732
  // Build and verify the loop tree without modifying the graph.  This
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   733
  // is useful to verify that all inputs properly dominate their uses.
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   734
  static void verify(PhaseIterGVN& igvn) {
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   735
#ifdef ASSERT
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   736
    PhaseIdealLoop v(igvn);
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   737
#endif
3bac3e882cd3 6862956: PhaseIdealLoop should have a CFG verification mode
never
parents: 2131
diff changeset
   738
  }
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   739
489c9b5090e2 Initial load
duke
parents:
diff changeset
   740
  // True if the method has at least 1 irreducible loop
489c9b5090e2 Initial load
duke
parents:
diff changeset
   741
  bool _has_irreducible_loops;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   742
489c9b5090e2 Initial load
duke
parents:
diff changeset
   743
  // Per-Node transform
489c9b5090e2 Initial load
duke
parents:
diff changeset
   744
  virtual Node *transform( Node *a_node ) { return 0; }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   745
489c9b5090e2 Initial load
duke
parents:
diff changeset
   746
  Node *is_counted_loop( Node *x, IdealLoopTree *loop );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   747
489c9b5090e2 Initial load
duke
parents:
diff changeset
   748
  // Return a post-walked LoopNode
489c9b5090e2 Initial load
duke
parents:
diff changeset
   749
  IdealLoopTree *get_loop( Node *n ) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   750
    // Dead nodes have no loop, so return the top level loop instead
489c9b5090e2 Initial load
duke
parents:
diff changeset
   751
    if (!has_node(n))  return _ltree_root;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   752
    assert(!has_ctrl(n), "");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   753
    return (IdealLoopTree*)_nodes[n->_idx];
489c9b5090e2 Initial load
duke
parents:
diff changeset
   754
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   755
489c9b5090e2 Initial load
duke
parents:
diff changeset
   756
  // Is 'n' a (nested) member of 'loop'?
489c9b5090e2 Initial load
duke
parents:
diff changeset
   757
  int is_member( const IdealLoopTree *loop, Node *n ) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   758
    return loop->is_member(get_loop(n)); }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   759
489c9b5090e2 Initial load
duke
parents:
diff changeset
   760
  // This is the basic building block of the loop optimizations.  It clones an
489c9b5090e2 Initial load
duke
parents:
diff changeset
   761
  // entire loop body.  It makes an old_new loop body mapping; with this
489c9b5090e2 Initial load
duke
parents:
diff changeset
   762
  // mapping you can find the new-loop equivalent to an old-loop node.  All
489c9b5090e2 Initial load
duke
parents:
diff changeset
   763
  // new-loop nodes are exactly equal to their old-loop counterparts, all
489c9b5090e2 Initial load
duke
parents:
diff changeset
   764
  // edges are the same.  All exits from the old-loop now have a RegionNode
489c9b5090e2 Initial load
duke
parents:
diff changeset
   765
  // that merges the equivalent new-loop path.  This is true even for the
489c9b5090e2 Initial load
duke
parents:
diff changeset
   766
  // normal "loop-exit" condition.  All uses of loop-invariant old-loop values
489c9b5090e2 Initial load
duke
parents:
diff changeset
   767
  // now come from (one or more) Phis that merge their new-loop equivalents.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   768
  // Parameter side_by_side_idom:
489c9b5090e2 Initial load
duke
parents:
diff changeset
   769
  //   When side_by_size_idom is NULL, the dominator tree is constructed for
489c9b5090e2 Initial load
duke
parents:
diff changeset
   770
  //      the clone loop to dominate the original.  Used in construction of
489c9b5090e2 Initial load
duke
parents:
diff changeset
   771
  //      pre-main-post loop sequence.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   772
  //   When nonnull, the clone and original are side-by-side, both are
489c9b5090e2 Initial load
duke
parents:
diff changeset
   773
  //      dominated by the passed in side_by_side_idom node.  Used in
489c9b5090e2 Initial load
duke
parents:
diff changeset
   774
  //      construction of unswitched loops.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   775
  void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   776
                   Node* side_by_side_idom = NULL);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   777
489c9b5090e2 Initial load
duke
parents:
diff changeset
   778
  // If we got the effect of peeling, either by actually peeling or by
489c9b5090e2 Initial load
duke
parents:
diff changeset
   779
  // making a pre-loop which must execute at least once, we can remove
489c9b5090e2 Initial load
duke
parents:
diff changeset
   780
  // all loop-invariant dominated tests in the main body.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   781
  void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   782
489c9b5090e2 Initial load
duke
parents:
diff changeset
   783
  // Generate code to do a loop peel for the given loop (and body).
489c9b5090e2 Initial load
duke
parents:
diff changeset
   784
  // old_new is a temp array.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   785
  void do_peeling( IdealLoopTree *loop, Node_List &old_new );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   786
489c9b5090e2 Initial load
duke
parents:
diff changeset
   787
  // Add pre and post loops around the given loop.  These loops are used
489c9b5090e2 Initial load
duke
parents:
diff changeset
   788
  // during RCE, unrolling and aligning loops.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   789
  void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   790
  // If Node n lives in the back_ctrl block, we clone a private version of n
489c9b5090e2 Initial load
duke
parents:
diff changeset
   791
  // in preheader_ctrl block and return that, otherwise return n.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   792
  Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   793
489c9b5090e2 Initial load
duke
parents:
diff changeset
   794
  // Take steps to maximally unroll the loop.  Peel any odd iterations, then
489c9b5090e2 Initial load
duke
parents:
diff changeset
   795
  // unroll to do double iterations.  The next round of major loop transforms
489c9b5090e2 Initial load
duke
parents:
diff changeset
   796
  // will repeat till the doubled loop body does all remaining iterations in 1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   797
  // pass.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   798
  void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   799
489c9b5090e2 Initial load
duke
parents:
diff changeset
   800
  // Unroll the loop body one step - make each trip do 2 iterations.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   801
  void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   802
489c9b5090e2 Initial load
duke
parents:
diff changeset
   803
  // Return true if exp is a constant times an induction var
489c9b5090e2 Initial load
duke
parents:
diff changeset
   804
  bool is_scaled_iv(Node* exp, Node* iv, int* p_scale);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   805
489c9b5090e2 Initial load
duke
parents:
diff changeset
   806
  // Return true if exp is a scaled induction var plus (or minus) constant
489c9b5090e2 Initial load
duke
parents:
diff changeset
   807
  bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   808
4643
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   809
  // Return true if proj is for "proj->[region->..]call_uct"
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   810
  bool is_uncommon_trap_proj(ProjNode* proj, bool must_reason_predicate = false);
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   811
  // Return true for    "if(test)-> proj -> ...
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   812
  //                          |
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   813
  //                          V
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   814
  //                      other_proj->[region->..]call_uct"
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   815
  bool is_uncommon_trap_if_pattern(ProjNode* proj, bool must_reason_predicate = false);
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   816
  // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   817
  ProjNode* create_new_if_for_predicate(ProjNode* cont_proj);
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   818
  // Find a good location to insert a predicate
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   819
  ProjNode* find_predicate_insertion_point(Node* start_c);
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   820
  // Construct a range check for a predicate if
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   821
  BoolNode* rc_predicate(Node* ctrl,
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   822
                         int scale, Node* offset,
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   823
                         Node* init, Node* limit, Node* stride,
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   824
                         Node* range);
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   825
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   826
  // Implementation of the loop predication to promote checks outside the loop
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   827
  bool loop_predication_impl(IdealLoopTree *loop);
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   828
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   829
  // Helper function to collect predicate for eliminating the useless ones
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   830
  void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1);
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   831
  void eliminate_useless_predicates();
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   832
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   833
  // Eliminate range-checks and other trip-counter vs loop-invariant tests.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   834
  void do_range_check( IdealLoopTree *loop, Node_List &old_new );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   835
489c9b5090e2 Initial load
duke
parents:
diff changeset
   836
  // Create a slow version of the loop by cloning the loop
489c9b5090e2 Initial load
duke
parents:
diff changeset
   837
  // and inserting an if to select fast-slow versions.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   838
  ProjNode* create_slow_version_of_loop(IdealLoopTree *loop,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   839
                                        Node_List &old_new);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   840
489c9b5090e2 Initial load
duke
parents:
diff changeset
   841
  // Clone loop with an invariant test (that does not exit) and
489c9b5090e2 Initial load
duke
parents:
diff changeset
   842
  // insert a clone of the test that selects which version to
489c9b5090e2 Initial load
duke
parents:
diff changeset
   843
  // execute.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   844
  void do_unswitching (IdealLoopTree *loop, Node_List &old_new);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   845
489c9b5090e2 Initial load
duke
parents:
diff changeset
   846
  // Find candidate "if" for unswitching
489c9b5090e2 Initial load
duke
parents:
diff changeset
   847
  IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   848
489c9b5090e2 Initial load
duke
parents:
diff changeset
   849
  // Range Check Elimination uses this function!
489c9b5090e2 Initial load
duke
parents:
diff changeset
   850
  // Constrain the main loop iterations so the affine function:
489c9b5090e2 Initial load
duke
parents:
diff changeset
   851
  //    scale_con * I + offset  <  limit
489c9b5090e2 Initial load
duke
parents:
diff changeset
   852
  // always holds true.  That is, either increase the number of iterations in
489c9b5090e2 Initial load
duke
parents:
diff changeset
   853
  // the pre-loop or the post-loop until the condition holds true in the main
489c9b5090e2 Initial load
duke
parents:
diff changeset
   854
  // loop.  Scale_con, offset and limit are all loop invariant.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   855
  void add_constraint( int stride_con, int scale_con, Node *offset, Node *limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   856
489c9b5090e2 Initial load
duke
parents:
diff changeset
   857
  // Partially peel loop up through last_peel node.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   858
  bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   859
489c9b5090e2 Initial load
duke
parents:
diff changeset
   860
  // Create a scheduled list of nodes control dependent on ctrl set.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   861
  void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   862
  // Has a use in the vector set
489c9b5090e2 Initial load
duke
parents:
diff changeset
   863
  bool has_use_in_set( Node* n, VectorSet& vset );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   864
  // Has use internal to the vector set (ie. not in a phi at the loop head)
489c9b5090e2 Initial load
duke
parents:
diff changeset
   865
  bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   866
  // clone "n" for uses that are outside of loop
489c9b5090e2 Initial load
duke
parents:
diff changeset
   867
  void clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   868
  // clone "n" for special uses that are in the not_peeled region
489c9b5090e2 Initial load
duke
parents:
diff changeset
   869
  void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   870
                                          VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   871
  // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
489c9b5090e2 Initial load
duke
parents:
diff changeset
   872
  void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   873
#ifdef ASSERT
489c9b5090e2 Initial load
duke
parents:
diff changeset
   874
  // Validate the loop partition sets: peel and not_peel
489c9b5090e2 Initial load
duke
parents:
diff changeset
   875
  bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   876
  // Ensure that uses outside of loop are of the right form
489c9b5090e2 Initial load
duke
parents:
diff changeset
   877
  bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   878
                                 uint orig_exit_idx, uint clone_exit_idx);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   879
  bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   880
#endif
489c9b5090e2 Initial load
duke
parents:
diff changeset
   881
489c9b5090e2 Initial load
duke
parents:
diff changeset
   882
  // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
489c9b5090e2 Initial load
duke
parents:
diff changeset
   883
  int stride_of_possible_iv( Node* iff );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   884
  bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   885
  // Return the (unique) control output node that's in the loop (if it exists.)
489c9b5090e2 Initial load
duke
parents:
diff changeset
   886
  Node* stay_in_loop( Node* n, IdealLoopTree *loop);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   887
  // Insert a signed compare loop exit cloned from an unsigned compare.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   888
  IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   889
  void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   890
  // Utility to register node "n" with PhaseIdealLoop
489c9b5090e2 Initial load
duke
parents:
diff changeset
   891
  void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   892
  // Utility to create an if-projection
489c9b5090e2 Initial load
duke
parents:
diff changeset
   893
  ProjNode* proj_clone(ProjNode* p, IfNode* iff);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   894
  // Force the iff control output to be the live_proj
489c9b5090e2 Initial load
duke
parents:
diff changeset
   895
  Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   896
  // Insert a region before an if projection
489c9b5090e2 Initial load
duke
parents:
diff changeset
   897
  RegionNode* insert_region_before_proj(ProjNode* proj);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   898
  // Insert a new if before an if projection
489c9b5090e2 Initial load
duke
parents:
diff changeset
   899
  ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   900
489c9b5090e2 Initial load
duke
parents:
diff changeset
   901
  // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   902
  // "Nearly" because all Nodes have been cloned from the original in the loop,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   903
  // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
489c9b5090e2 Initial load
duke
parents:
diff changeset
   904
  // through the Phi recursively, and return a Bool.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   905
  BoolNode *clone_iff( PhiNode *phi, IdealLoopTree *loop );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   906
  CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   907
489c9b5090e2 Initial load
duke
parents:
diff changeset
   908
489c9b5090e2 Initial load
duke
parents:
diff changeset
   909
  // Rework addressing expressions to get the most loop-invariant stuff
489c9b5090e2 Initial load
duke
parents:
diff changeset
   910
  // moved out.  We'd like to do all associative operators, but it's especially
489c9b5090e2 Initial load
duke
parents:
diff changeset
   911
  // important (common) to do address expressions.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   912
  Node *remix_address_expressions( Node *n );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   913
489c9b5090e2 Initial load
duke
parents:
diff changeset
   914
  // Attempt to use a conditional move instead of a phi/branch
489c9b5090e2 Initial load
duke
parents:
diff changeset
   915
  Node *conditional_move( Node *n );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   916
489c9b5090e2 Initial load
duke
parents:
diff changeset
   917
  // Reorganize offset computations to lower register pressure.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   918
  // Mostly prevent loop-fallout uses of the pre-incremented trip counter
489c9b5090e2 Initial load
duke
parents:
diff changeset
   919
  // (which are then alive with the post-incremented trip counter
489c9b5090e2 Initial load
duke
parents:
diff changeset
   920
  // forcing an extra register move)
489c9b5090e2 Initial load
duke
parents:
diff changeset
   921
  void reorg_offsets( IdealLoopTree *loop );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   922
489c9b5090e2 Initial load
duke
parents:
diff changeset
   923
  // Check for aggressive application of 'split-if' optimization,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   924
  // using basic block level info.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   925
  void  split_if_with_blocks     ( VectorSet &visited, Node_Stack &nstack );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   926
  Node *split_if_with_blocks_pre ( Node *n );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   927
  void  split_if_with_blocks_post( Node *n );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   928
  Node *has_local_phi_input( Node *n );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   929
  // Mark an IfNode as being dominated by a prior test,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   930
  // without actually altering the CFG (and hence IDOM info).
489c9b5090e2 Initial load
duke
parents:
diff changeset
   931
  void dominated_by( Node *prevdom, Node *iff );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   932
489c9b5090e2 Initial load
duke
parents:
diff changeset
   933
  // Split Node 'n' through merge point
489c9b5090e2 Initial load
duke
parents:
diff changeset
   934
  Node *split_thru_region( Node *n, Node *region );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   935
  // Split Node 'n' through merge point if there is enough win.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   936
  Node *split_thru_phi( Node *n, Node *region, int policy );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   937
  // Found an If getting its condition-code input from a Phi in the
489c9b5090e2 Initial load
duke
parents:
diff changeset
   938
  // same block.  Split thru the Region.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   939
  void do_split_if( Node *iff );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   940
489c9b5090e2 Initial load
duke
parents:
diff changeset
   941
private:
489c9b5090e2 Initial load
duke
parents:
diff changeset
   942
  // Return a type based on condition control flow
489c9b5090e2 Initial load
duke
parents:
diff changeset
   943
  const TypeInt* filtered_type( Node *n, Node* n_ctrl);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   944
  const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   945
 // Helpers for filtered type
489c9b5090e2 Initial load
duke
parents:
diff changeset
   946
  const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   947
489c9b5090e2 Initial load
duke
parents:
diff changeset
   948
  // Helper functions
489c9b5090e2 Initial load
duke
parents:
diff changeset
   949
  Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   950
  Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   951
  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 );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   952
  bool split_up( Node *n, Node *blk1, Node *blk2 );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   953
  void sink_use( Node *use, Node *post_loop );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   954
  Node *place_near_use( Node *useblock ) const;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   955
489c9b5090e2 Initial load
duke
parents:
diff changeset
   956
  bool _created_loop_node;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   957
public:
489c9b5090e2 Initial load
duke
parents:
diff changeset
   958
  void set_created_loop_node() { _created_loop_node = true; }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   959
  bool created_loop_node()     { return _created_loop_node; }
4643
61c659c91c57 6894779: Loop Predication for Loop Optimizer in C2
cfang
parents: 3676
diff changeset
   960
  void register_new_node( Node *n, Node *blk );
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   961
489c9b5090e2 Initial load
duke
parents:
diff changeset
   962
#ifndef PRODUCT
489c9b5090e2 Initial load
duke
parents:
diff changeset
   963
  void dump( ) const;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   964
  void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   965
  void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   966
  void verify() const;          // Major slow  :-)
489c9b5090e2 Initial load
duke
parents:
diff changeset
   967
  void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   968
  IdealLoopTree *get_loop_idx(Node* n) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   969
    // Dead nodes have no loop, so return the top level loop instead
489c9b5090e2 Initial load
duke
parents:
diff changeset
   970
    return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   971
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   972
  // Print some stats
489c9b5090e2 Initial load
duke
parents:
diff changeset
   973
  static void print_statistics();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   974
  static int _loop_invokes;     // Count of PhaseIdealLoop invokes
489c9b5090e2 Initial load
duke
parents:
diff changeset
   975
  static int _loop_work;        // Sum of PhaseIdealLoop x _unique
489c9b5090e2 Initial load
duke
parents:
diff changeset
   976
#endif
489c9b5090e2 Initial load
duke
parents:
diff changeset
   977
};
489c9b5090e2 Initial load
duke
parents:
diff changeset
   978
489c9b5090e2 Initial load
duke
parents:
diff changeset
   979
inline Node* IdealLoopTree::tail() {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   980
// Handle lazy update of _tail field
489c9b5090e2 Initial load
duke
parents:
diff changeset
   981
  Node *n = _tail;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   982
  //while( !n->in(0) )  // Skip dead CFG nodes
489c9b5090e2 Initial load
duke
parents:
diff changeset
   983
    //n = n->in(1);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   984
  if (n->in(0) == NULL)
489c9b5090e2 Initial load
duke
parents:
diff changeset
   985
    n = _phase->get_ctrl(n);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   986
  _tail = n;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   987
  return n;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   988
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   989
489c9b5090e2 Initial load
duke
parents:
diff changeset
   990
489c9b5090e2 Initial load
duke
parents:
diff changeset
   991
// Iterate over the loop tree using a preorder, left-to-right traversal.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   992
//
489c9b5090e2 Initial load
duke
parents:
diff changeset
   993
// Example that visits all counted loops from within PhaseIdealLoop
489c9b5090e2 Initial load
duke
parents:
diff changeset
   994
//
489c9b5090e2 Initial load
duke
parents:
diff changeset
   995
//  for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   996
//   IdealLoopTree* lpt = iter.current();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   997
//   if (!lpt->is_counted()) continue;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   998
//   ...
489c9b5090e2 Initial load
duke
parents:
diff changeset
   999
class LoopTreeIterator : public StackObj {
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1000
private:
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1001
  IdealLoopTree* _root;
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1002
  IdealLoopTree* _curnt;
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1003
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1004
public:
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1005
  LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1006
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1007
  bool done() { return _curnt == NULL; }       // Finished iterating?
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1008
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1009
  void next();                                 // Advance to next loop tree
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1010
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1011
  IdealLoopTree* current() { return _curnt; }  // Return current value of iterator.
489c9b5090e2 Initial load
duke
parents:
diff changeset
  1012
};