--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/opto/block.hpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,510 @@
+/*
+ * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// Optimization - Graph Style
+
+class Block;
+class CFGLoop;
+class MachCallNode;
+class Matcher;
+class RootNode;
+class VectorSet;
+struct Tarjan;
+
+//------------------------------Block_Array------------------------------------
+// Map dense integer indices to Blocks. Uses classic doubling-array trick.
+// Abstractly provides an infinite array of Block*'s, initialized to NULL.
+// Note that the constructor just zeros things, and since I use Arena
+// allocation I do not need a destructor to reclaim storage.
+class Block_Array : public ResourceObj {
+ uint _size; // allocated size, as opposed to formal limit
+ debug_only(uint _limit;) // limit to formal domain
+protected:
+ Block **_blocks;
+ void grow( uint i ); // Grow array node to fit
+
+public:
+ Arena *_arena; // Arena to allocate in
+
+ Block_Array(Arena *a) : _arena(a), _size(OptoBlockListSize) {
+ debug_only(_limit=0);
+ _blocks = NEW_ARENA_ARRAY( a, Block *, OptoBlockListSize );
+ for( int i = 0; i < OptoBlockListSize; i++ ) {
+ _blocks[i] = NULL;
+ }
+ }
+ Block *lookup( uint i ) const // Lookup, or NULL for not mapped
+ { return (i<Max()) ? _blocks[i] : (Block*)NULL; }
+ Block *operator[] ( uint i ) const // Lookup, or assert for not mapped
+ { assert( i < Max(), "oob" ); return _blocks[i]; }
+ // Extend the mapping: index i maps to Block *n.
+ void map( uint i, Block *n ) { if( i>=Max() ) grow(i); _blocks[i] = n; }
+ uint Max() const { debug_only(return _limit); return _size; }
+};
+
+
+class Block_List : public Block_Array {
+public:
+ uint _cnt;
+ Block_List() : Block_Array(Thread::current()->resource_area()), _cnt(0) {}
+ void push( Block *b ) { map(_cnt++,b); }
+ Block *pop() { return _blocks[--_cnt]; }
+ Block *rpop() { Block *b = _blocks[0]; _blocks[0]=_blocks[--_cnt]; return b;}
+ void remove( uint i );
+ void insert( uint i, Block *n );
+ uint size() const { return _cnt; }
+ void reset() { _cnt = 0; }
+};
+
+
+class CFGElement : public ResourceObj {
+ public:
+ float _freq; // Execution frequency (estimate)
+
+ CFGElement() : _freq(0.0f) {}
+ virtual bool is_block() { return false; }
+ virtual bool is_loop() { return false; }
+ Block* as_Block() { assert(is_block(), "must be block"); return (Block*)this; }
+ CFGLoop* as_CFGLoop() { assert(is_loop(), "must be loop"); return (CFGLoop*)this; }
+};
+
+//------------------------------Block------------------------------------------
+// This class defines a Basic Block.
+// Basic blocks are used during the output routines, and are not used during
+// any optimization pass. They are created late in the game.
+class Block : public CFGElement {
+ public:
+ // Nodes in this block, in order
+ Node_List _nodes;
+
+ // Basic blocks have a Node which defines Control for all Nodes pinned in
+ // this block. This Node is a RegionNode. Exception-causing Nodes
+ // (division, subroutines) and Phi functions are always pinned. Later,
+ // every Node will get pinned to some block.
+ Node *head() const { return _nodes[0]; }
+
+ // CAUTION: num_preds() is ONE based, so that predecessor numbers match
+ // input edges to Regions and Phis.
+ uint num_preds() const { return head()->req(); }
+ Node *pred(uint i) const { return head()->in(i); }
+
+ // Array of successor blocks, same size as projs array
+ Block_Array _succs;
+
+ // Basic blocks have some number of Nodes which split control to all
+ // following blocks. These Nodes are always Projections. The field in
+ // the Projection and the block-ending Node determine which Block follows.
+ uint _num_succs;
+
+ // Basic blocks also carry all sorts of good old fashioned DFS information
+ // used to find loops, loop nesting depth, dominators, etc.
+ uint _pre_order; // Pre-order DFS number
+
+ // Dominator tree
+ uint _dom_depth; // Depth in dominator tree for fast LCA
+ Block* _idom; // Immediate dominator block
+
+ CFGLoop *_loop; // Loop to which this block belongs
+ uint _rpo; // Number in reverse post order walk
+
+ virtual bool is_block() { return true; }
+ float succ_prob(uint i); // return probability of i'th successor
+
+ Block* dom_lca(Block* that); // Compute LCA in dominator tree.
+#ifdef ASSERT
+ bool dominates(Block* that) {
+ int dom_diff = this->_dom_depth - that->_dom_depth;
+ if (dom_diff > 0) return false;
+ for (; dom_diff < 0; dom_diff++) that = that->_idom;
+ return this == that;
+ }
+#endif
+
+ // Report the alignment required by this block. Must be a power of 2.
+ // The previous block will insert nops to get this alignment.
+ uint code_alignment();
+
+ // BLOCK_FREQUENCY is a sentinel to mark uses of constant block frequencies.
+ // It is currently also used to scale such frequencies relative to
+ // FreqCountInvocations relative to the old value of 1500.
+#define BLOCK_FREQUENCY(f) ((f * (float) 1500) / FreqCountInvocations)
+
+ // Register Pressure (estimate) for Splitting heuristic
+ uint _reg_pressure;
+ uint _ihrp_index;
+ uint _freg_pressure;
+ uint _fhrp_index;
+
+ // Mark and visited bits for an LCA calculation in insert_anti_dependences.
+ // Since they hold unique node indexes, they do not need reinitialization.
+ node_idx_t _raise_LCA_mark;
+ void set_raise_LCA_mark(node_idx_t x) { _raise_LCA_mark = x; }
+ node_idx_t raise_LCA_mark() const { return _raise_LCA_mark; }
+ node_idx_t _raise_LCA_visited;
+ void set_raise_LCA_visited(node_idx_t x) { _raise_LCA_visited = x; }
+ node_idx_t raise_LCA_visited() const { return _raise_LCA_visited; }
+
+ // Estimated size in bytes of first instructions in a loop.
+ uint _first_inst_size;
+ uint first_inst_size() const { return _first_inst_size; }
+ void set_first_inst_size(uint s) { _first_inst_size = s; }
+
+ // Compute the size of first instructions in this block.
+ uint compute_first_inst_size(uint& sum_size, uint inst_cnt, PhaseRegAlloc* ra);
+
+ // Compute alignment padding if the block needs it.
+ // Align a loop if loop's padding is less or equal to padding limit
+ // or the size of first instructions in the loop > padding.
+ uint alignment_padding(int current_offset) {
+ int block_alignment = code_alignment();
+ int max_pad = block_alignment-relocInfo::addr_unit();
+ if( max_pad > 0 ) {
+ assert(is_power_of_2(max_pad+relocInfo::addr_unit()), "");
+ int current_alignment = current_offset & max_pad;
+ if( current_alignment != 0 ) {
+ uint padding = (block_alignment-current_alignment) & max_pad;
+ if( !head()->is_Loop() ||
+ padding <= (uint)MaxLoopPad ||
+ first_inst_size() > padding ) {
+ return padding;
+ }
+ }
+ }
+ return 0;
+ }
+
+ // Connector blocks. Connector blocks are basic blocks devoid of
+ // instructions, but may have relevant non-instruction Nodes, such as
+ // Phis or MergeMems. Such blocks are discovered and marked during the
+ // RemoveEmpty phase, and elided during Output.
+ bool _connector;
+ void set_connector() { _connector = true; }
+ bool is_connector() const { return _connector; };
+
+ // Create a new Block with given head Node.
+ // Creates the (empty) predecessor arrays.
+ Block( Arena *a, Node *headnode )
+ : CFGElement(),
+ _nodes(a),
+ _succs(a),
+ _num_succs(0),
+ _pre_order(0),
+ _idom(0),
+ _loop(NULL),
+ _reg_pressure(0),
+ _ihrp_index(1),
+ _freg_pressure(0),
+ _fhrp_index(1),
+ _raise_LCA_mark(0),
+ _raise_LCA_visited(0),
+ _first_inst_size(999999),
+ _connector(false) {
+ _nodes.push(headnode);
+ }
+
+ // Index of 'end' Node
+ uint end_idx() const {
+ // %%%%% add a proj after every goto
+ // so (last->is_block_proj() != last) always, then simplify this code
+ // This will not give correct end_idx for block 0 when it only contains root.
+ int last_idx = _nodes.size() - 1;
+ Node *last = _nodes[last_idx];
+ assert(last->is_block_proj() == last || last->is_block_proj() == _nodes[last_idx - _num_succs], "");
+ return (last->is_block_proj() == last) ? last_idx : (last_idx - _num_succs);
+ }
+
+ // Basic blocks have a Node which ends them. This Node determines which
+ // basic block follows this one in the program flow. This Node is either an
+ // IfNode, a GotoNode, a JmpNode, or a ReturnNode.
+ Node *end() const { return _nodes[end_idx()]; }
+
+ // Add an instruction to an existing block. It must go after the head
+ // instruction and before the end instruction.
+ void add_inst( Node *n ) { _nodes.insert(end_idx(),n); }
+ // Find node in block
+ uint find_node( const Node *n ) const;
+ // Find and remove n from block list
+ void find_remove( const Node *n );
+
+ // Schedule a call next in the block
+ uint sched_call(Matcher &matcher, Block_Array &bbs, uint node_cnt, Node_List &worklist, int *ready_cnt, MachCallNode *mcall, VectorSet &next_call);
+
+ // Perform basic-block local scheduling
+ Node *select(PhaseCFG *cfg, Node_List &worklist, int *ready_cnt, VectorSet &next_call, uint sched_slot);
+ void set_next_call( Node *n, VectorSet &next_call, Block_Array &bbs );
+ void needed_for_next_call(Node *this_call, VectorSet &next_call, Block_Array &bbs);
+ bool schedule_local(PhaseCFG *cfg, Matcher &m, int *ready_cnt, VectorSet &next_call);
+ // Cleanup if any code lands between a Call and his Catch
+ void call_catch_cleanup(Block_Array &bbs);
+ // Detect implicit-null-check opportunities. Basically, find NULL checks
+ // with suitable memory ops nearby. Use the memory op to do the NULL check.
+ // I can generate a memory op if there is not one nearby.
+ void implicit_null_check(PhaseCFG *cfg, Node *proj, Node *val, int allowed_reasons);
+
+ // Return the empty status of a block
+ enum { not_empty, empty_with_goto, completely_empty };
+ int is_Empty() const;
+
+ // Forward through connectors
+ Block* non_connector() {
+ Block* s = this;
+ while (s->is_connector()) {
+ s = s->_succs[0];
+ }
+ return s;
+ }
+
+ // Successor block, after forwarding through connectors
+ Block* non_connector_successor(int i) const {
+ return _succs[i]->non_connector();
+ }
+
+ // Examine block's code shape to predict if it is not commonly executed.
+ bool has_uncommon_code() const;
+
+ // Use frequency calculations and code shape to predict if the block
+ // is uncommon.
+ bool is_uncommon( Block_Array &bbs ) const;
+
+#ifndef PRODUCT
+ // Debugging print of basic block
+ void dump_bidx(const Block* orig) const;
+ void dump_pred(const Block_Array *bbs, Block* orig) const;
+ void dump_head( const Block_Array *bbs ) const;
+ void dump( ) const;
+ void dump( const Block_Array *bbs ) const;
+#endif
+};
+
+
+//------------------------------PhaseCFG---------------------------------------
+// Build an array of Basic Block pointers, one per Node.
+class PhaseCFG : public Phase {
+ private:
+ // Build a proper looking cfg. Return count of basic blocks
+ uint build_cfg();
+
+ // Perform DFS search.
+ // Setup 'vertex' as DFS to vertex mapping.
+ // Setup 'semi' as vertex to DFS mapping.
+ // Set 'parent' to DFS parent.
+ uint DFS( Tarjan *tarjan );
+
+ // Helper function to insert a node into a block
+ void schedule_node_into_block( Node *n, Block *b );
+
+ // Set the basic block for pinned Nodes
+ void schedule_pinned_nodes( VectorSet &visited );
+
+ // I'll need a few machine-specific GotoNodes. Clone from this one.
+ MachNode *_goto;
+ void insert_goto_at(uint block_no, uint succ_no);
+
+ Block* insert_anti_dependences(Block* LCA, Node* load, bool verify = false);
+ void verify_anti_dependences(Block* LCA, Node* load) {
+ assert(LCA == _bbs[load->_idx], "should already be scheduled");
+ insert_anti_dependences(LCA, load, true);
+ }
+
+ public:
+ PhaseCFG( Arena *a, RootNode *r, Matcher &m );
+
+ uint _num_blocks; // Count of basic blocks
+ Block_List _blocks; // List of basic blocks
+ RootNode *_root; // Root of whole program
+ Block_Array _bbs; // Map Nodes to owning Basic Block
+ Block *_broot; // Basic block of root
+ uint _rpo_ctr;
+ CFGLoop* _root_loop;
+
+ // Per node latency estimation, valid only during GCM
+ GrowableArray<uint> _node_latency;
+
+#ifndef PRODUCT
+ bool _trace_opto_pipelining; // tracing flag
+#endif
+
+ // Build dominators
+ void Dominators();
+
+ // Estimate block frequencies based on IfNode probabilities
+ void Estimate_Block_Frequency();
+
+ // Global Code Motion. See Click's PLDI95 paper. Place Nodes in specific
+ // basic blocks; i.e. _bbs now maps _idx for all Nodes to some Block.
+ void GlobalCodeMotion( Matcher &m, uint unique, Node_List &proj_list );
+
+ // Compute the (backwards) latency of a node from the uses
+ void latency_from_uses(Node *n);
+
+ // Compute the (backwards) latency of a node from a single use
+ int latency_from_use(Node *n, const Node *def, Node *use);
+
+ // Compute the (backwards) latency of a node from the uses of this instruction
+ void partial_latency_of_defs(Node *n);
+
+ // Schedule Nodes early in their basic blocks.
+ bool schedule_early(VectorSet &visited, Node_List &roots);
+
+ // For each node, find the latest block it can be scheduled into
+ // and then select the cheapest block between the latest and earliest
+ // block to place the node.
+ void schedule_late(VectorSet &visited, Node_List &stack);
+
+ // Pick a block between early and late that is a cheaper alternative
+ // to late. Helper for schedule_late.
+ Block* hoist_to_cheaper_block(Block* LCA, Block* early, Node* self);
+
+ // Compute the instruction global latency with a backwards walk
+ void ComputeLatenciesBackwards(VectorSet &visited, Node_List &stack);
+
+ // Remove empty basic blocks
+ void RemoveEmpty();
+ bool MoveToNext(Block* bx, uint b_index);
+ void MoveToEnd(Block* bx, uint b_index);
+
+ // Check for NeverBranch at block end. This needs to become a GOTO to the
+ // true target. NeverBranch are treated as a conditional branch that always
+ // goes the same direction for most of the optimizer and are used to give a
+ // fake exit path to infinite loops. At this late stage they need to turn
+ // into Goto's so that when you enter the infinite loop you indeed hang.
+ void convert_NeverBranch_to_Goto(Block *b);
+
+ CFGLoop* create_loop_tree();
+
+ // Insert a node into a block, and update the _bbs
+ void insert( Block *b, uint idx, Node *n ) {
+ b->_nodes.insert( idx, n );
+ _bbs.map( n->_idx, b );
+ }
+
+#ifndef PRODUCT
+ bool trace_opto_pipelining() const { return _trace_opto_pipelining; }
+
+ // Debugging print of CFG
+ void dump( ) const; // CFG only
+ void _dump_cfg( const Node *end, VectorSet &visited ) const;
+ void verify() const;
+ void dump_headers();
+#else
+ bool trace_opto_pipelining() const { return false; }
+#endif
+};
+
+
+//------------------------------UnionFindInfo----------------------------------
+// Map Block indices to a block-index for a cfg-cover.
+// Array lookup in the optimized case.
+class UnionFind : public ResourceObj {
+ uint _cnt, _max;
+ uint* _indices;
+ ReallocMark _nesting; // assertion check for reallocations
+public:
+ UnionFind( uint max );
+ void reset( uint max ); // Reset to identity map for [0..max]
+
+ uint lookup( uint nidx ) const {
+ return _indices[nidx];
+ }
+ uint operator[] (uint nidx) const { return lookup(nidx); }
+
+ void map( uint from_idx, uint to_idx ) {
+ assert( from_idx < _cnt, "oob" );
+ _indices[from_idx] = to_idx;
+ }
+ void extend( uint from_idx, uint to_idx );
+
+ uint Size() const { return _cnt; }
+
+ uint Find( uint idx ) {
+ assert( idx < 65536, "Must fit into uint");
+ uint uf_idx = lookup(idx);
+ return (uf_idx == idx) ? uf_idx : Find_compress(idx);
+ }
+ uint Find_compress( uint idx );
+ uint Find_const( uint idx ) const;
+ void Union( uint idx1, uint idx2 );
+
+};
+
+//----------------------------BlockProbPair---------------------------
+// Ordered pair of Node*.
+class BlockProbPair VALUE_OBJ_CLASS_SPEC {
+protected:
+ Block* _target; // block target
+ float _prob; // probability of edge to block
+public:
+ BlockProbPair() : _target(NULL), _prob(0.0) {}
+ BlockProbPair(Block* b, float p) : _target(b), _prob(p) {}
+
+ Block* get_target() const { return _target; }
+ float get_prob() const { return _prob; }
+};
+
+//------------------------------CFGLoop-------------------------------------------
+class CFGLoop : public CFGElement {
+ int _id;
+ int _depth;
+ CFGLoop *_parent; // root of loop tree is the method level "pseudo" loop, it's parent is null
+ CFGLoop *_sibling; // null terminated list
+ CFGLoop *_child; // first child, use child's sibling to visit all immediately nested loops
+ GrowableArray<CFGElement*> _members; // list of members of loop
+ GrowableArray<BlockProbPair> _exits; // list of successor blocks and their probabilities
+ float _exit_prob; // probability any loop exit is taken on a single loop iteration
+ void update_succ_freq(Block* b, float freq);
+
+ public:
+ CFGLoop(int id) :
+ CFGElement(),
+ _id(id),
+ _depth(0),
+ _parent(NULL),
+ _sibling(NULL),
+ _child(NULL),
+ _exit_prob(1.0f) {}
+ CFGLoop* parent() { return _parent; }
+ void push_pred(Block* blk, int i, Block_List& worklist, Block_Array& node_to_blk);
+ void add_member(CFGElement *s) { _members.push(s); }
+ void add_nested_loop(CFGLoop* cl);
+ Block* head() {
+ assert(_members.at(0)->is_block(), "head must be a block");
+ Block* hd = _members.at(0)->as_Block();
+ assert(hd->_loop == this, "just checking");
+ assert(hd->head()->is_Loop(), "must begin with loop head node");
+ return hd;
+ }
+ Block* backedge_block(); // Return the block on the backedge of the loop (else NULL)
+ void compute_loop_depth(int depth);
+ void compute_freq(); // compute frequency with loop assuming head freq 1.0f
+ void scale_freq(); // scale frequency by loop trip count (including outer loops)
+ bool in_loop_nest(Block* b);
+ float trip_count() const { return 1.0f / _exit_prob; }
+ virtual bool is_loop() { return true; }
+ int id() { return _id; }
+
+#ifndef PRODUCT
+ void dump( ) const;
+ void dump_tree() const;
+#endif
+};