class CmpNode;

class CountedLoopEndNode;

class CountedLoopNode;

class IdealLoopTree;

class LoopNode;

class Node;

class PhaseIdealLoop;

class VectorSet;

struct small_cache;

class LoopNode : public RegionNode {

// Size is bigger to hold the flags. However, the flags do not change

// the semantics so it does not appear in the hash & cmp functions.

virtual uint size_of() const { return sizeof(*this); }

protected:

short _loop_flags;

// Names for flag bitfields

enum { pre_post_main=0, inner_loop=8, partial_peel_loop=16, partial_peel_failed=32 };

char _unswitch_count;

enum { _unswitch_max=3 };

public:

// Names for edge indices

enum { Self=0, EntryControl, LoopBackControl };

int is_inner_loop() const { return _loop_flags & inner_loop; }

void set_inner_loop() { _loop_flags |= inner_loop; }

int is_partial_peel_loop() const { return _loop_flags & partial_peel_loop; }

void set_partial_peel_loop() { _loop_flags |= partial_peel_loop; }

int partial_peel_has_failed() const { return _loop_flags & partial_peel_failed; }

void mark_partial_peel_failed() { _loop_flags |= partial_peel_failed; }

int unswitch_max() { return _unswitch_max; }

int unswitch_count() { return _unswitch_count; }

void set_unswitch_count(int val) {

assert (val <= unswitch_max(), "too many unswitches");

_unswitch_count = val;

}

LoopNode( Node *entry, Node *backedge ) : RegionNode(3), _loop_flags(0), _unswitch_count(0) {

init_class_id(Class_Loop);

init_req(EntryControl, entry);

init_req(LoopBackControl, backedge);

}

virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);

virtual int Opcode() const;

bool can_be_counted_loop(PhaseTransform* phase) const {

return req() == 3 && in(0) != NULL &&

in(1) != NULL && phase->type(in(1)) != Type::TOP &&

in(2) != NULL && phase->type(in(2)) != Type::TOP;

}

#ifndef PRODUCT

virtual void dump_spec(outputStream *st) const;

#endif

};

class CountedLoopNode : public LoopNode {

// Size is bigger to hold _main_idx. However, _main_idx does not change

// the semantics so it does not appear in the hash & cmp functions.

virtual uint size_of() const { return sizeof(*this); }

// For Pre- and Post-loops during debugging ONLY, this holds the index of

// the Main CountedLoop. Used to assert that we understand the graph shape.

node_idx_t _main_idx;

// Known trip count calculated by policy_maximally_unroll

int _trip_count;

// Expected trip count from profile data

float _profile_trip_cnt;

// Log2 of original loop bodies in unrolled loop

int _unrolled_count_log2;

// Node count prior to last unrolling - used to decide if

// unroll,optimize,unroll,optimize,... is making progress

int _node_count_before_unroll;

public:

CountedLoopNode( Node *entry, Node *backedge )

: LoopNode(entry, backedge), _trip_count(max_jint),

_profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0),

_node_count_before_unroll(0) {

init_class_id(Class_CountedLoop);

// Initialize _trip_count to the largest possible value.

// Will be reset (lower) if the loop's trip count is known.

}

virtual int Opcode() const;

virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);

Node *init_control() const { return in(EntryControl); }

Node *back_control() const { return in(LoopBackControl); }

CountedLoopEndNode *loopexit() const;

Node *init_trip() const;

Node *stride() const;

int stride_con() const;

bool stride_is_con() const;

Node *limit() const;

Node *incr() const;

Node *phi() const;

// Match increment with optional truncation

static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type);

// A 'main' loop has a pre-loop and a post-loop. The 'main' loop

// can run short a few iterations and may start a few iterations in.

// It will be RCE'd and unrolled and aligned.

// A following 'post' loop will run any remaining iterations. Used

// during Range Check Elimination, the 'post' loop will do any final

// iterations with full checks. Also used by Loop Unrolling, where

// the 'post' loop will do any epilog iterations needed. Basically,

// a 'post' loop can not profitably be further unrolled or RCE'd.

// A preceding 'pre' loop will run at least 1 iteration (to do peeling),

// it may do under-flow checks for RCE and may do alignment iterations

// so the following main loop 'knows' that it is striding down cache

// lines.

// A 'main' loop that is ONLY unrolled or peeled, never RCE'd or

// Aligned, may be missing it's pre-loop.

enum { Normal=0, Pre=1, Main=2, Post=3, PrePostFlagsMask=3, Main_Has_No_Pre_Loop=4 };

int is_normal_loop() const { return (_loop_flags&PrePostFlagsMask) == Normal; }

int is_pre_loop () const { return (_loop_flags&PrePostFlagsMask) == Pre; }

int is_main_loop () const { return (_loop_flags&PrePostFlagsMask) == Main; }

int is_post_loop () const { return (_loop_flags&PrePostFlagsMask) == Post; }

int is_main_no_pre_loop() const { return _loop_flags & Main_Has_No_Pre_Loop; }

void set_main_no_pre_loop() { _loop_flags |= Main_Has_No_Pre_Loop; }

void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }

void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; }

void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }

void set_normal_loop( ) { _loop_flags &= ~PrePostFlagsMask; }

void set_trip_count(int tc) { _trip_count = tc; }

int trip_count() { return _trip_count; }

void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }

float profile_trip_cnt() { return _profile_trip_cnt; }

void double_unrolled_count() { _unrolled_count_log2++; }

int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }

void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }

int node_count_before_unroll() { return _node_count_before_unroll; }

#ifndef PRODUCT

virtual void dump_spec(outputStream *st) const;

#endif

};

class CountedLoopEndNode : public IfNode {

public:

enum { TestControl, TestValue };

CountedLoopEndNode( Node *control, Node *test, float prob, float cnt )

: IfNode( control, test, prob, cnt) {

init_class_id(Class_CountedLoopEnd);

}

virtual int Opcode() const;

Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; }

Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }

Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; }

Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; }

Node *phi() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }

Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }

int stride_con() const;

bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); }

BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; }

CountedLoopNode *loopnode() const {

Node *ln = phi()->in(0);

assert( ln->Opcode() == Op_CountedLoop, "malformed loop" );

return (CountedLoopNode*)ln; }

#ifndef PRODUCT

virtual void dump_spec(outputStream *st) const;

#endif

};

inline CountedLoopEndNode *CountedLoopNode::loopexit() const {

Node *bc = back_control();

if( bc == NULL ) return NULL;

Node *le = bc->in(0);

if( le->Opcode() != Op_CountedLoopEnd )

return NULL;

return (CountedLoopEndNode*)le;

}

inline Node *CountedLoopNode::init_trip() const { return loopexit() ? loopexit()->init_trip() : NULL; }

inline Node *CountedLoopNode::stride() const { return loopexit() ? loopexit()->stride() : NULL; }

inline int CountedLoopNode::stride_con() const { return loopexit() ? loopexit()->stride_con() : 0; }

inline bool CountedLoopNode::stride_is_con() const { return loopexit() && loopexit()->stride_is_con(); }

inline Node *CountedLoopNode::limit() const { return loopexit() ? loopexit()->limit() : NULL; }

inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; }

inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; }

class IdealLoopTree : public ResourceObj {

public:

IdealLoopTree *_parent; // Parent in loop tree

IdealLoopTree *_next; // Next sibling in loop tree

IdealLoopTree *_child; // First child in loop tree

// The head-tail backedge defines the loop.

// If tail is NULL then this loop has multiple backedges as part of the

// same loop. During cleanup I'll peel off the multiple backedges; merge

// them at the loop bottom and flow 1 real backedge into the loop.

Node *_head; // Head of loop

Node *_tail; // Tail of loop

inline Node *tail(); // Handle lazy update of _tail field

PhaseIdealLoop* _phase;

Node_List _body; // Loop body for inner loops

uint8 _nest; // Nesting depth

uint8 _irreducible:1, // True if irreducible

_has_call:1, // True if has call safepoint

_has_sfpt:1, // True if has non-call safepoint

_rce_candidate:1; // True if candidate for range check elimination

Node_List* _required_safept; // A inner loop cannot delete these safepts;

bool _allow_optimizations; // Allow loop optimizations

IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )

: _parent(0), _next(0), _child(0),

_head(head), _tail(tail),

_phase(phase),

_required_safept(NULL),

_allow_optimizations(true),

_nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0)

{ }

// Is 'l' a member of 'this'?

int is_member( const IdealLoopTree *l ) const; // Test for nested membership

// Set loop nesting depth. Accumulate has_call bits.

int set_nest( uint depth );

// Split out multiple fall-in edges from the loop header. Move them to a

// private RegionNode before the loop. This becomes the loop landing pad.

void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );

// Split out the outermost loop from this shared header.

void split_outer_loop( PhaseIdealLoop *phase );

// Merge all the backedges from the shared header into a private Region.

// Feed that region as the one backedge to this loop.

void merge_many_backedges( PhaseIdealLoop *phase );

// Split shared headers and insert loop landing pads.

// Insert a LoopNode to replace the RegionNode.

// Returns TRUE if loop tree is structurally changed.

bool beautify_loops( PhaseIdealLoop *phase );

// Perform iteration-splitting on inner loops. Split iterations to avoid

// range checks or one-shot null checks.

void iteration_split( PhaseIdealLoop *phase, Node_List &old_new );

// Driver for various flavors of iteration splitting

void iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );

// Given dominators, try to find loops with calls that must always be

// executed (call dominates loop tail). These loops do not need non-call

// safepoints (ncsfpt).

void check_safepts(VectorSet &visited, Node_List &stack);

// Allpaths backwards scan from loop tail, terminating each path at first safepoint

// encountered.

void allpaths_check_safepts(VectorSet &visited, Node_List &stack);

// Convert to counted loops where possible

void counted_loop( PhaseIdealLoop *phase );

// Check for Node being a loop-breaking test

Node *is_loop_exit(Node *iff) const;

// Returns true if ctrl is executed on every complete iteration

bool dominates_backedge(Node* ctrl);

// Remove simplistic dead code from loop body

void DCE_loop_body();

// Look for loop-exit tests with my 50/50 guesses from the Parsing stage.

// Replace with a 1-in-10 exit guess.

void adjust_loop_exit_prob( PhaseIdealLoop *phase );

// Return TRUE or FALSE if the loop should never be RCE'd or aligned.

// Useful for unrolling loops with NO array accesses.

bool policy_peel_only( PhaseIdealLoop *phase ) const;

// Return TRUE or FALSE if the loop should be unswitched -- clone

// loop with an invariant test

bool policy_unswitching( PhaseIdealLoop *phase ) const;

// Micro-benchmark spamming. Remove empty loops.

bool policy_do_remove_empty_loop( PhaseIdealLoop *phase );

// Return TRUE or FALSE if the loop should be peeled or not. Peel if we can

// make some loop-invariant test (usually a null-check) happen before the

// loop.

bool policy_peeling( PhaseIdealLoop *phase ) const;

// Return TRUE or FALSE if the loop should be maximally unrolled. Stash any

// known trip count in the counted loop node.

bool policy_maximally_unroll( PhaseIdealLoop *phase ) const;

// Return TRUE or FALSE if the loop should be unrolled or not. Unroll if

// the loop is a CountedLoop and the body is small enough.

bool policy_unroll( PhaseIdealLoop *phase ) const;

// Return TRUE or FALSE if the loop should be range-check-eliminated.

// Gather a list of IF tests that are dominated by iteration splitting;

// also gather the end of the first split and the start of the 2nd split.

bool policy_range_check( PhaseIdealLoop *phase ) const;

// Return TRUE or FALSE if the loop should be cache-line aligned.

// Gather the expression that does the alignment. Note that only

// one array base can be aligned in a loop (unless the VM guarentees

// mutual alignment). Note that if we vectorize short memory ops

// into longer memory ops, we may want to increase alignment.

bool policy_align( PhaseIdealLoop *phase ) const;

// Compute loop trip count from profile data

void compute_profile_trip_cnt( PhaseIdealLoop *phase );

// Reassociate invariant expressions.

void reassociate_invariants(PhaseIdealLoop *phase);

// Reassociate invariant add and subtract expressions.

Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase);

// Return nonzero index of invariant operand if invariant and variant

// are combined with an Add or Sub. Helper for reassoicate_invariants.

int is_invariant_addition(Node* n, PhaseIdealLoop *phase);

// Return true if n is invariant

bool is_invariant(Node* n) const;

// Put loop body on igvn work list

void record_for_igvn();

bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); }

bool is_inner() { return is_loop() && _child == NULL; }

bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); }

#ifndef PRODUCT

void dump_head( ) const; // Dump loop head only

void dump() const; // Dump this loop recursively

void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const;

#endif

};

class PhaseIdealLoop : public PhaseTransform {

friend class IdealLoopTree;

friend class SuperWord;

// Pre-computed def-use info

PhaseIterGVN &_igvn;

// Head of loop tree

IdealLoopTree *_ltree_root;

// Array of pre-order numbers, plus post-visited bit.

// ZERO for not pre-visited. EVEN for pre-visited but not post-visited.

// ODD for post-visited. Other bits are the pre-order number.

uint *_preorders;

uint _max_preorder;

// Allocate _preorders[] array

void allocate_preorders() {

_max_preorder = C->unique()+8;

_preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);

memset(_preorders, 0, sizeof(uint) * _max_preorder);

}

// Allocate _preorders[] array

void reallocate_preorders() {

if ( _max_preorder < C->unique() ) {

_preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());

_max_preorder = C->unique();

}

memset(_preorders, 0, sizeof(uint) * _max_preorder);

}

// Check to grow _preorders[] array for the case when build_loop_tree_impl()

// adds new nodes.

void check_grow_preorders( ) {

if ( _max_preorder < C->unique() ) {

uint newsize = _max_preorder<<1; // double size of array

_preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);

memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));

_max_preorder = newsize;

}

}

// Check for pre-visited. Zero for NOT visited; non-zero for visited.

int is_visited( Node *n ) const { return _preorders[n->_idx]; }

// Pre-order numbers are written to the Nodes array as low-bit-set values.

void set_preorder_visited( Node *n, int pre_order ) {

assert( !is_visited( n ), "already set" );

_preorders[n->_idx] = (pre_order<<1);

};

// Return pre-order number.

int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }

// Check for being post-visited.

// Should be previsited already (checked with assert(is_visited(n))).

int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }

// Mark as post visited

void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }

// Set/get control node out. Set lower bit to distinguish from IdealLoopTree

// Returns true if "n" is a data node, false if it's a control node.

bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; }

// clear out dead code after build_loop_late

Node_List _deadlist;

// Support for faster execution of get_late_ctrl()/dom_lca()

// when a node has many uses and dominator depth is deep.

Node_Array _dom_lca_tags;

void init_dom_lca_tags();

void clear_dom_lca_tags();

// Inline wrapper for frequent cases:

// 1) only one use

// 2) a use is the same as the current LCA passed as 'n1'

Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {

assert( n->is_CFG(), "" );

// Fast-path NULL lca

if( lca != NULL && lca != n ) {

assert( lca->is_CFG(), "" );

// find LCA of all uses

n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );

}

return find_non_split_ctrl(n);

}

Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );

// true if CFG node d dominates CFG node n

bool is_dominator(Node *d, Node *n);

// Helper function for directing control inputs away from CFG split

// points.

Node *find_non_split_ctrl( Node *ctrl ) const {

if (ctrl != NULL) {

if (ctrl->is_MultiBranch()) {

ctrl = ctrl->in(0);

}

assert(ctrl->is_CFG(), "CFG");

}

return ctrl;

}

public:

bool has_node( Node* n ) const { return _nodes[n->_idx] != NULL; }

// check if transform created new nodes that need _ctrl recorded

Node *get_late_ctrl( Node *n, Node *early );

Node *get_early_ctrl( Node *n );

void set_early_ctrl( Node *n );

void set_subtree_ctrl( Node *root );

void set_ctrl( Node *n, Node *ctrl ) {

assert( !has_node(n) || has_ctrl(n), "" );

assert( ctrl->in(0), "cannot set dead control node" );

assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );

_nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) );

}

// Set control and update loop membership

void set_ctrl_and_loop(Node* n, Node* ctrl) {

IdealLoopTree* old_loop = get_loop(get_ctrl(n));

IdealLoopTree* new_loop = get_loop(ctrl);

if (old_loop != new_loop) {

if (old_loop->_child == NULL) old_loop->_body.yank(n);

if (new_loop->_child == NULL) new_loop->_body.push(n);

}

set_ctrl(n, ctrl);

}

// Control nodes can be replaced or subsumed. During this pass they

// get their replacement Node in slot 1. Instead of updating the block

// location of all Nodes in the subsumed block, we lazily do it. As we

// pull such a subsumed block out of the array, we write back the final

// correct block.

Node *get_ctrl( Node *i ) {

assert(has_node(i), "");

Node *n = get_ctrl_no_update(i);

_nodes.map( i->_idx, (Node*)((intptr_t)n + 1) );

assert(has_node(i) && has_ctrl(i), "");

assert(n == find_non_split_ctrl(n), "must return legal ctrl" );

return n;

}

private:

Node *get_ctrl_no_update( Node *i ) const {

assert( has_ctrl(i), "" );

Node *n = (Node*)(((intptr_t)_nodes[i->_idx]) & ~1);

if (!n->in(0)) {

// Skip dead CFG nodes

do {

n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1);

} while (!n->in(0));

n = find_non_split_ctrl(n);

}

return n;

}

// Check for loop being set

// "n" must be a control node. Returns true if "n" is known to be in a loop.

bool has_loop( Node *n ) const {

assert(!has_node(n) || !has_ctrl(n), "");

return has_node(n);

}

// Set loop

void set_loop( Node *n, IdealLoopTree *loop ) {

_nodes.map(n->_idx, (Node*)loop);

}

// Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace

// the 'old_node' with 'new_node'. Kill old-node. Add a reference

// from old_node to new_node to support the lazy update. Reference

// replaces loop reference, since that is not neede for dead node.

public:

void lazy_update( Node *old_node, Node *new_node ) {

assert( old_node != new_node, "no cycles please" );

//old_node->set_req( 1, new_node /*NO DU INFO*/ );

// Nodes always have DU info now, so re-use the side array slot

// for this node to provide the forwarding pointer.

_nodes.map( old_node->_idx, (Node*)((intptr_t)new_node + 1) );

}

void lazy_replace( Node *old_node, Node *new_node ) {

_igvn.hash_delete(old_node);

_igvn.subsume_node( old_node, new_node );

lazy_update( old_node, new_node );

}

void lazy_replace_proj( Node *old_node, Node *new_node ) {

assert( old_node->req() == 1, "use this for Projs" );

_igvn.hash_delete(old_node); // Must hash-delete before hacking edges

old_node->add_req( NULL );

lazy_replace( old_node, new_node );

}

private:

// Place 'n' in some loop nest, where 'n' is a CFG node

void build_loop_tree();

int build_loop_tree_impl( Node *n, int pre_order );

// Insert loop into the existing loop tree. 'innermost' is a leaf of the

// loop tree, not the root.

IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );

// Place Data nodes in some loop nest

void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack, const PhaseIdealLoop *verify_me );

void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack, const PhaseIdealLoop *verify_me );

void build_loop_late_post ( Node* n, const PhaseIdealLoop *verify_me );

// Array of immediate dominance info for each CFG node indexed by node idx

private:

uint _idom_size;

Node **_idom; // Array of immediate dominators

uint *_dom_depth; // Used for fast LCA test

GrowableArray<uint>* _dom_stk; // For recomputation of dom depth

Node* idom_no_update(Node* d) const {

assert(d->_idx < _idom_size, "oob");

Node* n = _idom[d->_idx];

assert(n != NULL,"Bad immediate dominator info.");

while (n->in(0) == NULL) { // Skip dead CFG nodes

//n = n->in(1);

n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1);

assert(n != NULL,"Bad immediate dominator info.");

}

return n;

}

Node *idom(Node* d) const {

uint didx = d->_idx;

Node *n = idom_no_update(d);

_idom[didx] = n; // Lazily remove dead CFG nodes from table.

return n;

}

uint dom_depth(Node* d) const {

assert(d->_idx < _idom_size, "");

return _dom_depth[d->_idx];

}

void set_idom(Node* d, Node* n, uint dom_depth);

// Locally compute IDOM using dom_lca call

Node *compute_idom( Node *region ) const;

// Recompute dom_depth

void recompute_dom_depth();

// Is safept not required by an outer loop?

bool is_deleteable_safept(Node* sfpt);

public:

// Dominators for the sea of nodes

void Dominators();

Node *dom_lca( Node *n1, Node *n2 ) const {

return find_non_split_ctrl(dom_lca_internal(n1, n2));

}

Node *dom_lca_internal( Node *n1, Node *n2 ) const;

// Compute the Ideal Node to Loop mapping

PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me, bool do_split_ifs );

// True if the method has at least 1 irreducible loop

bool _has_irreducible_loops;

// Per-Node transform

virtual Node *transform( Node *a_node ) { return 0; }

Node *is_counted_loop( Node *x, IdealLoopTree *loop );

// Return a post-walked LoopNode

IdealLoopTree *get_loop( Node *n ) const {

// Dead nodes have no loop, so return the top level loop instead

if (!has_node(n)) return _ltree_root;

assert(!has_ctrl(n), "");

return (IdealLoopTree*)_nodes[n->_idx];

}

// Is 'n' a (nested) member of 'loop'?

int is_member( const IdealLoopTree *loop, Node *n ) const {

return loop->is_member(get_loop(n)); }

// This is the basic building block of the loop optimizations. It clones an

// entire loop body. It makes an old_new loop body mapping; with this

// mapping you can find the new-loop equivalent to an old-loop node. All

// new-loop nodes are exactly equal to their old-loop counterparts, all

// edges are the same. All exits from the old-loop now have a RegionNode

// that merges the equivalent new-loop path. This is true even for the

// normal "loop-exit" condition. All uses of loop-invariant old-loop values

// now come from (one or more) Phis that merge their new-loop equivalents.

// Parameter side_by_side_idom:

// When side_by_size_idom is NULL, the dominator tree is constructed for

// the clone loop to dominate the original. Used in construction of

// pre-main-post loop sequence.

// When nonnull, the clone and original are side-by-side, both are

// dominated by the passed in side_by_side_idom node. Used in

// construction of unswitched loops.

void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,

Node* side_by_side_idom = NULL);

// If we got the effect of peeling, either by actually peeling or by

// making a pre-loop which must execute at least once, we can remove

// all loop-invariant dominated tests in the main body.

void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );

// Generate code to do a loop peel for the given loop (and body).

// old_new is a temp array.

void do_peeling( IdealLoopTree *loop, Node_List &old_new );

// Add pre and post loops around the given loop. These loops are used

// during RCE, unrolling and aligning loops.

void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );

// If Node n lives in the back_ctrl block, we clone a private version of n

// in preheader_ctrl block and return that, otherwise return n.

Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n );

// Take steps to maximally unroll the loop. Peel any odd iterations, then

// unroll to do double iterations. The next round of major loop transforms

// will repeat till the doubled loop body does all remaining iterations in 1

// pass.

void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );

// Unroll the loop body one step - make each trip do 2 iterations.

void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );

// Return true if exp is a constant times an induction var

bool is_scaled_iv(Node* exp, Node* iv, int* p_scale);

// Return true if exp is a scaled induction var plus (or minus) constant

bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0);

// Eliminate range-checks and other trip-counter vs loop-invariant tests.

void do_range_check( IdealLoopTree *loop, Node_List &old_new );

// Create a slow version of the loop by cloning the loop

// and inserting an if to select fast-slow versions.

ProjNode* create_slow_version_of_loop(IdealLoopTree *loop,

Node_List &old_new);

// Clone loop with an invariant test (that does not exit) and

// insert a clone of the test that selects which version to

// execute.

void do_unswitching (IdealLoopTree *loop, Node_List &old_new);

// Find candidate "if" for unswitching

IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const;

// Range Check Elimination uses this function!

// Constrain the main loop iterations so the affine function:

// scale_con * I + offset < limit

// always holds true. That is, either increase the number of iterations in

// the pre-loop or the post-loop until the condition holds true in the main

// loop. Scale_con, offset and limit are all loop invariant.

void add_constraint( int stride_con, int scale_con, Node *offset, Node *limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit );

// Partially peel loop up through last_peel node.

bool partial_peel( IdealLoopTree *loop, Node_List &old_new );

// Create a scheduled list of nodes control dependent on ctrl set.

void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );

// Has a use in the vector set

bool has_use_in_set( Node* n, VectorSet& vset );

// Has use internal to the vector set (ie. not in a phi at the loop head)

bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );

// clone "n" for uses that are outside of loop

void clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );

// clone "n" for special uses that are in the not_peeled region

void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,

VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );

// Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist

void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );

#ifdef ASSERT

// Validate the loop partition sets: peel and not_peel

bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );

// Ensure that uses outside of loop are of the right form

bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,

uint orig_exit_idx, uint clone_exit_idx);

bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);

#endif

// Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)

int stride_of_possible_iv( Node* iff );

bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }

// Return the (unique) control output node that's in the loop (if it exists.)

Node* stay_in_loop( Node* n, IdealLoopTree *loop);

// Insert a signed compare loop exit cloned from an unsigned compare.

IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);

void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);

// Utility to register node "n" with PhaseIdealLoop

void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth);

// Utility to create an if-projection

ProjNode* proj_clone(ProjNode* p, IfNode* iff);

// Force the iff control output to be the live_proj

Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);

// Insert a region before an if projection

RegionNode* insert_region_before_proj(ProjNode* proj);

// Insert a new if before an if projection

ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);

// Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.

// "Nearly" because all Nodes have been cloned from the original in the loop,

// but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs

// through the Phi recursively, and return a Bool.

BoolNode *clone_iff( PhiNode *phi, IdealLoopTree *loop );

CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop );

// Rework addressing expressions to get the most loop-invariant stuff

// moved out. We'd like to do all associative operators, but it's especially

// important (common) to do address expressions.

Node *remix_address_expressions( Node *n );

// Attempt to use a conditional move instead of a phi/branch

Node *conditional_move( Node *n );

// Reorganize offset computations to lower register pressure.

// Mostly prevent loop-fallout uses of the pre-incremented trip counter

// (which are then alive with the post-incremented trip counter

// forcing an extra register move)

void reorg_offsets( IdealLoopTree *loop );

// Check for aggressive application of 'split-if' optimization,

// using basic block level info.

void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack );

Node *split_if_with_blocks_pre ( Node *n );

void split_if_with_blocks_post( Node *n );

Node *has_local_phi_input( Node *n );

// Mark an IfNode as being dominated by a prior test,

// without actually altering the CFG (and hence IDOM info).

void dominated_by( Node *prevdom, Node *iff );

// Split Node 'n' through merge point

Node *split_thru_region( Node *n, Node *region );

// Split Node 'n' through merge point if there is enough win.

Node *split_thru_phi( Node *n, Node *region, int policy );

// Found an If getting its condition-code input from a Phi in the

// same block. Split thru the Region.

void do_split_if( Node *iff );

private:

// Return a type based on condition control flow

const TypeInt* filtered_type( Node *n, Node* n_ctrl);

const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); }

// Helpers for filtered type

const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);

// Helper functions

void register_new_node( Node *n, Node *blk );

Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );

Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );

void handle_use( Node *use, Node *def, small_cache *cache, Node *region_dom, Node *new_false, Node *new_true, Node *old_false, Node *old_true );

bool split_up( Node *n, Node *blk1, Node *blk2 );

void sink_use( Node *use, Node *post_loop );

Node *place_near_use( Node *useblock ) const;

bool _created_loop_node;

public:

void set_created_loop_node() { _created_loop_node = true; }

bool created_loop_node() { return _created_loop_node; }

#ifndef PRODUCT

void dump( ) const;

void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const;

void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const;

void verify() const; // Major slow :-)

void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const;

IdealLoopTree *get_loop_idx(Node* n) const {

// Dead nodes have no loop, so return the top level loop instead

return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root;

}

// Print some stats

static void print_statistics();

static int _loop_invokes; // Count of PhaseIdealLoop invokes

static int _loop_work; // Sum of PhaseIdealLoop x _unique

#endif

};

inline Node* IdealLoopTree::tail() {

Node *n = _tail;

//while( !n->in(0) ) // Skip dead CFG nodes

//n = n->in(1);

if (n->in(0) == NULL)

n = _phase->get_ctrl(n);

_tail = n;

return n;

}

class LoopTreeIterator : public StackObj {

private:

IdealLoopTree* _root;

IdealLoopTree* _curnt;

public:

LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}

bool done() { return _curnt == NULL; } // Finished iterating?

void next(); // Advance to next loop tree

IdealLoopTree* current() { return _curnt; } // Return current value of iterator.

};