| /* |
| * Copyright 1997-2006 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 |
| |
| #include "incls/_precompiled.incl" |
| #include "incls/_block.cpp.incl" |
| |
| |
| //----------------------------------------------------------------------------- |
| void Block_Array::grow( uint i ) { |
| assert(i >= Max(), "must be an overflow"); |
| debug_only(_limit = i+1); |
| if( i < _size ) return; |
| if( !_size ) { |
| _size = 1; |
| _blocks = (Block**)_arena->Amalloc( _size * sizeof(Block*) ); |
| _blocks[0] = NULL; |
| } |
| uint old = _size; |
| while( i >= _size ) _size <<= 1; // Double to fit |
| _blocks = (Block**)_arena->Arealloc( _blocks, old*sizeof(Block*),_size*sizeof(Block*)); |
| Copy::zero_to_bytes( &_blocks[old], (_size-old)*sizeof(Block*) ); |
| } |
| |
| //============================================================================= |
| void Block_List::remove(uint i) { |
| assert(i < _cnt, "index out of bounds"); |
| Copy::conjoint_words_to_lower((HeapWord*)&_blocks[i+1], (HeapWord*)&_blocks[i], ((_cnt-i-1)*sizeof(Block*))); |
| pop(); // shrink list by one block |
| } |
| |
| void Block_List::insert(uint i, Block *b) { |
| push(b); // grow list by one block |
| Copy::conjoint_words_to_higher((HeapWord*)&_blocks[i], (HeapWord*)&_blocks[i+1], ((_cnt-i-1)*sizeof(Block*))); |
| _blocks[i] = b; |
| } |
| |
| |
| //============================================================================= |
| |
| uint Block::code_alignment() { |
| // Check for Root block |
| if( _pre_order == 0 ) return CodeEntryAlignment; |
| // Check for Start block |
| if( _pre_order == 1 ) return InteriorEntryAlignment; |
| // Check for loop alignment |
| Node *h = head(); |
| if( h->is_Loop() && h->as_Loop()->is_inner_loop() ) { |
| // Pre- and post-loops have low trip count so do not bother with |
| // NOPs for align loop head. The constants are hidden from tuning |
| // but only because my "divide by 4" heuristic surely gets nearly |
| // all possible gain (a "do not align at all" heuristic has a |
| // chance of getting a really tiny gain). |
| if( h->is_CountedLoop() && (h->as_CountedLoop()->is_pre_loop() || |
| h->as_CountedLoop()->is_post_loop()) ) |
| return (OptoLoopAlignment > 4) ? (OptoLoopAlignment>>2) : 1; |
| // Loops with low backedge frequency should not be aligned. |
| Node *n = h->in(LoopNode::LoopBackControl)->in(0); |
| if( n->is_MachIf() && n->as_MachIf()->_prob < 0.01 ) { |
| return 1; // Loop does not loop, more often than not! |
| } |
| return OptoLoopAlignment; // Otherwise align loop head |
| } |
| return 1; // no particular alignment |
| } |
| |
| //----------------------------------------------------------------------------- |
| // Compute the size of first 'inst_cnt' instructions in this block. |
| // Return the number of instructions left to compute if the block has |
| // less then 'inst_cnt' instructions. |
| uint Block::compute_first_inst_size(uint& sum_size, uint inst_cnt, |
| PhaseRegAlloc* ra) { |
| uint last_inst = _nodes.size(); |
| for( uint j = 0; j < last_inst && inst_cnt > 0; j++ ) { |
| uint inst_size = _nodes[j]->size(ra); |
| if( inst_size > 0 ) { |
| inst_cnt--; |
| uint sz = sum_size + inst_size; |
| if( sz <= (uint)OptoLoopAlignment ) { |
| // Compute size of instructions which fit into fetch buffer only |
| // since all inst_cnt instructions will not fit even if we align them. |
| sum_size = sz; |
| } else { |
| return 0; |
| } |
| } |
| } |
| return inst_cnt; |
| } |
| |
| //----------------------------------------------------------------------------- |
| uint Block::find_node( const Node *n ) const { |
| for( uint i = 0; i < _nodes.size(); i++ ) { |
| if( _nodes[i] == n ) |
| return i; |
| } |
| ShouldNotReachHere(); |
| return 0; |
| } |
| |
| // Find and remove n from block list |
| void Block::find_remove( const Node *n ) { |
| _nodes.remove(find_node(n)); |
| } |
| |
| //------------------------------is_Empty--------------------------------------- |
| // Return empty status of a block. Empty blocks contain only the head, other |
| // ideal nodes, and an optional trailing goto. |
| int Block::is_Empty() const { |
| |
| // Root or start block is not considered empty |
| if (head()->is_Root() || head()->is_Start()) { |
| return not_empty; |
| } |
| |
| int success_result = completely_empty; |
| int end_idx = _nodes.size()-1; |
| |
| // Check for ending goto |
| if ((end_idx > 0) && (_nodes[end_idx]->is_Goto())) { |
| success_result = empty_with_goto; |
| end_idx--; |
| } |
| |
| // Unreachable blocks are considered empty |
| if (num_preds() <= 1) { |
| return success_result; |
| } |
| |
| // Ideal nodes are allowable in empty blocks: skip them Only MachNodes |
| // turn directly into code, because only MachNodes have non-trivial |
| // emit() functions. |
| while ((end_idx > 0) && !_nodes[end_idx]->is_Mach()) { |
| end_idx--; |
| } |
| |
| // No room for any interesting instructions? |
| if (end_idx == 0) { |
| return success_result; |
| } |
| |
| return not_empty; |
| } |
| |
| //------------------------------has_uncommon_code------------------------------ |
| // Return true if the block's code implies that it is not likely to be |
| // executed infrequently. Check to see if the block ends in a Halt or |
| // a low probability call. |
| bool Block::has_uncommon_code() const { |
| Node* en = end(); |
| |
| if (en->is_Goto()) |
| en = en->in(0); |
| if (en->is_Catch()) |
| en = en->in(0); |
| if (en->is_Proj() && en->in(0)->is_MachCall()) { |
| MachCallNode* call = en->in(0)->as_MachCall(); |
| if (call->cnt() != COUNT_UNKNOWN && call->cnt() <= PROB_UNLIKELY_MAG(4)) { |
| // This is true for slow-path stubs like new_{instance,array}, |
| // slow_arraycopy, complete_monitor_locking, uncommon_trap. |
| // The magic number corresponds to the probability of an uncommon_trap, |
| // even though it is a count not a probability. |
| return true; |
| } |
| } |
| |
| int op = en->is_Mach() ? en->as_Mach()->ideal_Opcode() : en->Opcode(); |
| return op == Op_Halt; |
| } |
| |
| //------------------------------is_uncommon------------------------------------ |
| // True if block is low enough frequency or guarded by a test which |
| // mostly does not go here. |
| bool Block::is_uncommon( Block_Array &bbs ) const { |
| // Initial blocks must never be moved, so are never uncommon. |
| if (head()->is_Root() || head()->is_Start()) return false; |
| |
| // Check for way-low freq |
| if( _freq < BLOCK_FREQUENCY(0.00001f) ) return true; |
| |
| // Look for code shape indicating uncommon_trap or slow path |
| if (has_uncommon_code()) return true; |
| |
| const float epsilon = 0.05f; |
| const float guard_factor = PROB_UNLIKELY_MAG(4) / (1.f - epsilon); |
| uint uncommon_preds = 0; |
| uint freq_preds = 0; |
| uint uncommon_for_freq_preds = 0; |
| |
| for( uint i=1; i<num_preds(); i++ ) { |
| Block* guard = bbs[pred(i)->_idx]; |
| // Check to see if this block follows its guard 1 time out of 10000 |
| // or less. |
| // |
| // See list of magnitude-4 unlikely probabilities in cfgnode.hpp which |
| // we intend to be "uncommon", such as slow-path TLE allocation, |
| // predicted call failure, and uncommon trap triggers. |
| // |
| // Use an epsilon value of 5% to allow for variability in frequency |
| // predictions and floating point calculations. The net effect is |
| // that guard_factor is set to 9500. |
| // |
| // Ignore low-frequency blocks. |
| // The next check is (guard->_freq < 1.e-5 * 9500.). |
| if(guard->_freq*BLOCK_FREQUENCY(guard_factor) < BLOCK_FREQUENCY(0.00001f)) { |
| uncommon_preds++; |
| } else { |
| freq_preds++; |
| if( _freq < guard->_freq * guard_factor ) { |
| uncommon_for_freq_preds++; |
| } |
| } |
| } |
| if( num_preds() > 1 && |
| // The block is uncommon if all preds are uncommon or |
| (uncommon_preds == (num_preds()-1) || |
| // it is uncommon for all frequent preds. |
| uncommon_for_freq_preds == freq_preds) ) { |
| return true; |
| } |
| return false; |
| } |
| |
| //------------------------------dump------------------------------------------- |
| #ifndef PRODUCT |
| void Block::dump_bidx(const Block* orig) const { |
| if (_pre_order) tty->print("B%d",_pre_order); |
| else tty->print("N%d", head()->_idx); |
| |
| if (Verbose && orig != this) { |
| // Dump the original block's idx |
| tty->print(" ("); |
| orig->dump_bidx(orig); |
| tty->print(")"); |
| } |
| } |
| |
| void Block::dump_pred(const Block_Array *bbs, Block* orig) const { |
| if (is_connector()) { |
| for (uint i=1; i<num_preds(); i++) { |
| Block *p = ((*bbs)[pred(i)->_idx]); |
| p->dump_pred(bbs, orig); |
| } |
| } else { |
| dump_bidx(orig); |
| tty->print(" "); |
| } |
| } |
| |
| void Block::dump_head( const Block_Array *bbs ) const { |
| // Print the basic block |
| dump_bidx(this); |
| tty->print(": #\t"); |
| |
| // Print the incoming CFG edges and the outgoing CFG edges |
| for( uint i=0; i<_num_succs; i++ ) { |
| non_connector_successor(i)->dump_bidx(_succs[i]); |
| tty->print(" "); |
| } |
| tty->print("<- "); |
| if( head()->is_block_start() ) { |
| for (uint i=1; i<num_preds(); i++) { |
| Node *s = pred(i); |
| if (bbs) { |
| Block *p = (*bbs)[s->_idx]; |
| p->dump_pred(bbs, p); |
| } else { |
| while (!s->is_block_start()) |
| s = s->in(0); |
| tty->print("N%d ", s->_idx ); |
| } |
| } |
| } else |
| tty->print("BLOCK HEAD IS JUNK "); |
| |
| // Print loop, if any |
| const Block *bhead = this; // Head of self-loop |
| Node *bh = bhead->head(); |
| if( bbs && bh->is_Loop() && !head()->is_Root() ) { |
| LoopNode *loop = bh->as_Loop(); |
| const Block *bx = (*bbs)[loop->in(LoopNode::LoopBackControl)->_idx]; |
| while (bx->is_connector()) { |
| bx = (*bbs)[bx->pred(1)->_idx]; |
| } |
| tty->print("\tLoop: B%d-B%d ", bhead->_pre_order, bx->_pre_order); |
| // Dump any loop-specific bits, especially for CountedLoops. |
| loop->dump_spec(tty); |
| } |
| tty->print(" Freq: %g",_freq); |
| if( Verbose || WizardMode ) { |
| tty->print(" IDom: %d/#%d", _idom ? _idom->_pre_order : 0, _dom_depth); |
| tty->print(" RegPressure: %d",_reg_pressure); |
| tty->print(" IHRP Index: %d",_ihrp_index); |
| tty->print(" FRegPressure: %d",_freg_pressure); |
| tty->print(" FHRP Index: %d",_fhrp_index); |
| } |
| tty->print_cr(""); |
| } |
| |
| void Block::dump() const { dump(0); } |
| |
| void Block::dump( const Block_Array *bbs ) const { |
| dump_head(bbs); |
| uint cnt = _nodes.size(); |
| for( uint i=0; i<cnt; i++ ) |
| _nodes[i]->dump(); |
| tty->print("\n"); |
| } |
| #endif |
| |
| //============================================================================= |
| //------------------------------PhaseCFG--------------------------------------- |
| PhaseCFG::PhaseCFG( Arena *a, RootNode *r, Matcher &m ) : |
| Phase(CFG), |
| _bbs(a), |
| _root(r) |
| #ifndef PRODUCT |
| , _trace_opto_pipelining(TraceOptoPipelining || C->method_has_option("TraceOptoPipelining")) |
| #endif |
| { |
| ResourceMark rm; |
| // I'll need a few machine-specific GotoNodes. Make an Ideal GotoNode, |
| // then Match it into a machine-specific Node. Then clone the machine |
| // Node on demand. |
| Node *x = new (C, 1) GotoNode(NULL); |
| x->init_req(0, x); |
| _goto = m.match_tree(x); |
| assert(_goto != NULL, ""); |
| _goto->set_req(0,_goto); |
| |
| // Build the CFG in Reverse Post Order |
| _num_blocks = build_cfg(); |
| _broot = _bbs[_root->_idx]; |
| } |
| |
| //------------------------------build_cfg-------------------------------------- |
| // Build a proper looking CFG. Make every block begin with either a StartNode |
| // or a RegionNode. Make every block end with either a Goto, If or Return. |
| // The RootNode both starts and ends it's own block. Do this with a recursive |
| // backwards walk over the control edges. |
| uint PhaseCFG::build_cfg() { |
| Arena *a = Thread::current()->resource_area(); |
| VectorSet visited(a); |
| |
| // Allocate stack with enough space to avoid frequent realloc |
| Node_Stack nstack(a, C->unique() >> 1); |
| nstack.push(_root, 0); |
| uint sum = 0; // Counter for blocks |
| |
| while (nstack.is_nonempty()) { |
| // node and in's index from stack's top |
| // 'np' is _root (see above) or RegionNode, StartNode: we push on stack |
| // only nodes which point to the start of basic block (see below). |
| Node *np = nstack.node(); |
| // idx > 0, except for the first node (_root) pushed on stack |
| // at the beginning when idx == 0. |
| // We will use the condition (idx == 0) later to end the build. |
| uint idx = nstack.index(); |
| Node *proj = np->in(idx); |
| const Node *x = proj->is_block_proj(); |
| // Does the block end with a proper block-ending Node? One of Return, |
| // If or Goto? (This check should be done for visited nodes also). |
| if (x == NULL) { // Does not end right... |
| Node *g = _goto->clone(); // Force it to end in a Goto |
| g->set_req(0, proj); |
| np->set_req(idx, g); |
| x = proj = g; |
| } |
| if (!visited.test_set(x->_idx)) { // Visit this block once |
| // Skip any control-pinned middle'in stuff |
| Node *p = proj; |
| do { |
| proj = p; // Update pointer to last Control |
| p = p->in(0); // Move control forward |
| } while( !p->is_block_proj() && |
| !p->is_block_start() ); |
| // Make the block begin with one of Region or StartNode. |
| if( !p->is_block_start() ) { |
| RegionNode *r = new (C, 2) RegionNode( 2 ); |
| r->init_req(1, p); // Insert RegionNode in the way |
| proj->set_req(0, r); // Insert RegionNode in the way |
| p = r; |
| } |
| // 'p' now points to the start of this basic block |
| |
| // Put self in array of basic blocks |
| Block *bb = new (_bbs._arena) Block(_bbs._arena,p); |
| _bbs.map(p->_idx,bb); |
| _bbs.map(x->_idx,bb); |
| if( x != p ) // Only for root is x == p |
| bb->_nodes.push((Node*)x); |
| |
| // Now handle predecessors |
| ++sum; // Count 1 for self block |
| uint cnt = bb->num_preds(); |
| for (int i = (cnt - 1); i > 0; i-- ) { // For all predecessors |
| Node *prevproj = p->in(i); // Get prior input |
| assert( !prevproj->is_Con(), "dead input not removed" ); |
| // Check to see if p->in(i) is a "control-dependent" CFG edge - |
| // i.e., it splits at the source (via an IF or SWITCH) and merges |
| // at the destination (via a many-input Region). |
| // This breaks critical edges. The RegionNode to start the block |
| // will be added when <p,i> is pulled off the node stack |
| if ( cnt > 2 ) { // Merging many things? |
| assert( prevproj== bb->pred(i),""); |
| if(prevproj->is_block_proj() != prevproj) { // Control-dependent edge? |
| // Force a block on the control-dependent edge |
| Node *g = _goto->clone(); // Force it to end in a Goto |
| g->set_req(0,prevproj); |
| p->set_req(i,g); |
| } |
| } |
| nstack.push(p, i); // 'p' is RegionNode or StartNode |
| } |
| } else { // Post-processing visited nodes |
| nstack.pop(); // remove node from stack |
| // Check if it the fist node pushed on stack at the beginning. |
| if (idx == 0) break; // end of the build |
| // Find predecessor basic block |
| Block *pb = _bbs[x->_idx]; |
| // Insert into nodes array, if not already there |
| if( !_bbs.lookup(proj->_idx) ) { |
| assert( x != proj, "" ); |
| // Map basic block of projection |
| _bbs.map(proj->_idx,pb); |
| pb->_nodes.push(proj); |
| } |
| // Insert self as a child of my predecessor block |
| pb->_succs.map(pb->_num_succs++, _bbs[np->_idx]); |
| assert( pb->_nodes[ pb->_nodes.size() - pb->_num_succs ]->is_block_proj(), |
| "too many control users, not a CFG?" ); |
| } |
| } |
| // Return number of basic blocks for all children and self |
| return sum; |
| } |
| |
| //------------------------------insert_goto_at--------------------------------- |
| // Inserts a goto & corresponding basic block between |
| // block[block_no] and its succ_no'th successor block |
| void PhaseCFG::insert_goto_at(uint block_no, uint succ_no) { |
| // get block with block_no |
| assert(block_no < _num_blocks, "illegal block number"); |
| Block* in = _blocks[block_no]; |
| // get successor block succ_no |
| assert(succ_no < in->_num_succs, "illegal successor number"); |
| Block* out = in->_succs[succ_no]; |
| // Compute frequency of the new block. Do this before inserting |
| // new block in case succ_prob() needs to infer the probability from |
| // surrounding blocks. |
| float freq = in->_freq * in->succ_prob(succ_no); |
| // get ProjNode corresponding to the succ_no'th successor of the in block |
| ProjNode* proj = in->_nodes[in->_nodes.size() - in->_num_succs + succ_no]->as_Proj(); |
| // create region for basic block |
| RegionNode* region = new (C, 2) RegionNode(2); |
| region->init_req(1, proj); |
| // setup corresponding basic block |
| Block* block = new (_bbs._arena) Block(_bbs._arena, region); |
| _bbs.map(region->_idx, block); |
| C->regalloc()->set_bad(region->_idx); |
| // add a goto node |
| Node* gto = _goto->clone(); // get a new goto node |
| gto->set_req(0, region); |
| // add it to the basic block |
| block->_nodes.push(gto); |
| _bbs.map(gto->_idx, block); |
| C->regalloc()->set_bad(gto->_idx); |
| // hook up successor block |
| block->_succs.map(block->_num_succs++, out); |
| // remap successor's predecessors if necessary |
| for (uint i = 1; i < out->num_preds(); i++) { |
| if (out->pred(i) == proj) out->head()->set_req(i, gto); |
| } |
| // remap predecessor's successor to new block |
| in->_succs.map(succ_no, block); |
| // Set the frequency of the new block |
| block->_freq = freq; |
| // add new basic block to basic block list |
| _blocks.insert(block_no + 1, block); |
| _num_blocks++; |
| } |
| |
| //------------------------------no_flip_branch--------------------------------- |
| // Does this block end in a multiway branch that cannot have the default case |
| // flipped for another case? |
| static bool no_flip_branch( Block *b ) { |
| int branch_idx = b->_nodes.size() - b->_num_succs-1; |
| if( branch_idx < 1 ) return false; |
| Node *bra = b->_nodes[branch_idx]; |
| if( bra->is_Catch() ) return true; |
| if( bra->is_Mach() ) { |
| if( bra->is_MachNullCheck() ) return true; |
| int iop = bra->as_Mach()->ideal_Opcode(); |
| if( iop == Op_FastLock || iop == Op_FastUnlock ) |
| return true; |
| } |
| return false; |
| } |
| |
| //------------------------------convert_NeverBranch_to_Goto-------------------- |
| // 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 PhaseCFG::convert_NeverBranch_to_Goto(Block *b) { |
| // Find true target |
| int end_idx = b->end_idx(); |
| int idx = b->_nodes[end_idx+1]->as_Proj()->_con; |
| Block *succ = b->_succs[idx]; |
| Node* gto = _goto->clone(); // get a new goto node |
| gto->set_req(0, b->head()); |
| Node *bp = b->_nodes[end_idx]; |
| b->_nodes.map(end_idx,gto); // Slam over NeverBranch |
| _bbs.map(gto->_idx, b); |
| C->regalloc()->set_bad(gto->_idx); |
| b->_nodes.pop(); // Yank projections |
| b->_nodes.pop(); // Yank projections |
| b->_succs.map(0,succ); // Map only successor |
| b->_num_succs = 1; |
| // remap successor's predecessors if necessary |
| uint j; |
| for( j = 1; j < succ->num_preds(); j++) |
| if( succ->pred(j)->in(0) == bp ) |
| succ->head()->set_req(j, gto); |
| // Kill alternate exit path |
| Block *dead = b->_succs[1-idx]; |
| for( j = 1; j < dead->num_preds(); j++) |
| if( dead->pred(j)->in(0) == bp ) |
| break; |
| // Scan through block, yanking dead path from |
| // all regions and phis. |
| dead->head()->del_req(j); |
| for( int k = 1; dead->_nodes[k]->is_Phi(); k++ ) |
| dead->_nodes[k]->del_req(j); |
| } |
| |
| //------------------------------MoveToNext------------------------------------- |
| // Helper function to move block bx to the slot following b_index. Return |
| // true if the move is successful, otherwise false |
| bool PhaseCFG::MoveToNext(Block* bx, uint b_index) { |
| if (bx == NULL) return false; |
| |
| // Return false if bx is already scheduled. |
| uint bx_index = bx->_pre_order; |
| if ((bx_index <= b_index) && (_blocks[bx_index] == bx)) { |
| return false; |
| } |
| |
| // Find the current index of block bx on the block list |
| bx_index = b_index + 1; |
| while( bx_index < _num_blocks && _blocks[bx_index] != bx ) bx_index++; |
| assert(_blocks[bx_index] == bx, "block not found"); |
| |
| // If the previous block conditionally falls into bx, return false, |
| // because moving bx will create an extra jump. |
| for(uint k = 1; k < bx->num_preds(); k++ ) { |
| Block* pred = _bbs[bx->pred(k)->_idx]; |
| if (pred == _blocks[bx_index-1]) { |
| if (pred->_num_succs != 1) { |
| return false; |
| } |
| } |
| } |
| |
| // Reinsert bx just past block 'b' |
| _blocks.remove(bx_index); |
| _blocks.insert(b_index + 1, bx); |
| return true; |
| } |
| |
| //------------------------------MoveToEnd-------------------------------------- |
| // Move empty and uncommon blocks to the end. |
| void PhaseCFG::MoveToEnd(Block *b, uint i) { |
| int e = b->is_Empty(); |
| if (e != Block::not_empty) { |
| if (e == Block::empty_with_goto) { |
| // Remove the goto, but leave the block. |
| b->_nodes.pop(); |
| } |
| // Mark this block as a connector block, which will cause it to be |
| // ignored in certain functions such as non_connector_successor(). |
| b->set_connector(); |
| } |
| // Move the empty block to the end, and don't recheck. |
| _blocks.remove(i); |
| _blocks.push(b); |
| } |
| |
| //------------------------------RemoveEmpty------------------------------------ |
| // Remove empty basic blocks and useless branches. |
| void PhaseCFG::RemoveEmpty() { |
| // Move uncommon blocks to the end |
| uint last = _num_blocks; |
| uint i; |
| assert( _blocks[0] == _broot, "" ); |
| for( i = 1; i < last; i++ ) { |
| Block *b = _blocks[i]; |
| |
| // 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. |
| if( b->_nodes[b->end_idx()]->Opcode() == Op_NeverBranch ) |
| convert_NeverBranch_to_Goto(b); |
| |
| // Look for uncommon blocks and move to end. |
| if( b->is_uncommon(_bbs) ) { |
| MoveToEnd(b, i); |
| last--; // No longer check for being uncommon! |
| if( no_flip_branch(b) ) { // Fall-thru case must follow? |
| b = _blocks[i]; // Find the fall-thru block |
| MoveToEnd(b, i); |
| last--; |
| } |
| i--; // backup block counter post-increment |
| } |
| } |
| |
| // Remove empty blocks |
| uint j1; |
| last = _num_blocks; |
| for( i=0; i < last; i++ ) { |
| Block *b = _blocks[i]; |
| if (i > 0) { |
| if (b->is_Empty() != Block::not_empty) { |
| MoveToEnd(b, i); |
| last--; |
| i--; |
| } |
| } |
| } // End of for all blocks |
| |
| // Fixup final control flow for the blocks. Remove jump-to-next |
| // block. If neither arm of a IF follows the conditional branch, we |
| // have to add a second jump after the conditional. We place the |
| // TRUE branch target in succs[0] for both GOTOs and IFs. |
| for( i=0; i < _num_blocks; i++ ) { |
| Block *b = _blocks[i]; |
| b->_pre_order = i; // turn pre-order into block-index |
| |
| // Connector blocks need no further processing. |
| if (b->is_connector()) { |
| assert((i+1) == _num_blocks || _blocks[i+1]->is_connector(), |
| "All connector blocks should sink to the end"); |
| continue; |
| } |
| assert(b->is_Empty() != Block::completely_empty, |
| "Empty blocks should be connectors"); |
| |
| Block *bnext = (i < _num_blocks-1) ? _blocks[i+1] : NULL; |
| Block *bs0 = b->non_connector_successor(0); |
| |
| // Check for multi-way branches where I cannot negate the test to |
| // exchange the true and false targets. |
| if( no_flip_branch( b ) ) { |
| // Find fall through case - if must fall into its target |
| int branch_idx = b->_nodes.size() - b->_num_succs; |
| for (uint j2 = 0; j2 < b->_num_succs; j2++) { |
| const ProjNode* p = b->_nodes[branch_idx + j2]->as_Proj(); |
| if (p->_con == 0) { |
| // successor j2 is fall through case |
| if (b->non_connector_successor(j2) != bnext) { |
| // but it is not the next block => insert a goto |
| insert_goto_at(i, j2); |
| } |
| // Put taken branch in slot 0 |
| if( j2 == 0 && b->_num_succs == 2) { |
| // Flip targets in succs map |
| Block *tbs0 = b->_succs[0]; |
| Block *tbs1 = b->_succs[1]; |
| b->_succs.map( 0, tbs1 ); |
| b->_succs.map( 1, tbs0 ); |
| } |
| break; |
| } |
| } |
| // Remove all CatchProjs |
| for (j1 = 0; j1 < b->_num_succs; j1++) b->_nodes.pop(); |
| |
| } else if (b->_num_succs == 1) { |
| // Block ends in a Goto? |
| if (bnext == bs0) { |
| // We fall into next block; remove the Goto |
| b->_nodes.pop(); |
| } |
| |
| } else if( b->_num_succs == 2 ) { // Block ends in a If? |
| // Get opcode of 1st projection (matches _succs[0]) |
| // Note: Since this basic block has 2 exits, the last 2 nodes must |
| // be projections (in any order), the 3rd last node must be |
| // the IfNode (we have excluded other 2-way exits such as |
| // CatchNodes already). |
| MachNode *iff = b->_nodes[b->_nodes.size()-3]->as_Mach(); |
| ProjNode *proj0 = b->_nodes[b->_nodes.size()-2]->as_Proj(); |
| ProjNode *proj1 = b->_nodes[b->_nodes.size()-1]->as_Proj(); |
| |
| // Assert that proj0 and succs[0] match up. Similarly for proj1 and succs[1]. |
| assert(proj0->raw_out(0) == b->_succs[0]->head(), "Mismatch successor 0"); |
| assert(proj1->raw_out(0) == b->_succs[1]->head(), "Mismatch successor 1"); |
| |
| Block *bs1 = b->non_connector_successor(1); |
| |
| // Check for neither successor block following the current |
| // block ending in a conditional. If so, move one of the |
| // successors after the current one, provided that the |
| // successor was previously unscheduled, but moveable |
| // (i.e., all paths to it involve a branch). |
| if( bnext != bs0 && bnext != bs1 ) { |
| |
| // Choose the more common successor based on the probability |
| // of the conditional branch. |
| Block *bx = bs0; |
| Block *by = bs1; |
| |
| // _prob is the probability of taking the true path. Make |
| // p the probability of taking successor #1. |
| float p = iff->as_MachIf()->_prob; |
| if( proj0->Opcode() == Op_IfTrue ) { |
| p = 1.0 - p; |
| } |
| |
| // Prefer successor #1 if p > 0.5 |
| if (p > PROB_FAIR) { |
| bx = bs1; |
| by = bs0; |
| } |
| |
| // Attempt the more common successor first |
| if (MoveToNext(bx, i)) { |
| bnext = bx; |
| } else if (MoveToNext(by, i)) { |
| bnext = by; |
| } |
| } |
| |
| // Check for conditional branching the wrong way. Negate |
| // conditional, if needed, so it falls into the following block |
| // and branches to the not-following block. |
| |
| // Check for the next block being in succs[0]. We are going to branch |
| // to succs[0], so we want the fall-thru case as the next block in |
| // succs[1]. |
| if (bnext == bs0) { |
| // Fall-thru case in succs[0], so flip targets in succs map |
| Block *tbs0 = b->_succs[0]; |
| Block *tbs1 = b->_succs[1]; |
| b->_succs.map( 0, tbs1 ); |
| b->_succs.map( 1, tbs0 ); |
| // Flip projection for each target |
| { ProjNode *tmp = proj0; proj0 = proj1; proj1 = tmp; } |
| |
| } else if( bnext == bs1 ) { // Fall-thru is already in succs[1] |
| |
| } else { // Else need a double-branch |
| |
| // The existing conditional branch need not change. |
| // Add a unconditional branch to the false target. |
| // Alas, it must appear in its own block and adding a |
| // block this late in the game is complicated. Sigh. |
| insert_goto_at(i, 1); |
| } |
| |
| // Make sure we TRUE branch to the target |
| if( proj0->Opcode() == Op_IfFalse ) |
| iff->negate(); |
| |
| b->_nodes.pop(); // Remove IfFalse & IfTrue projections |
| b->_nodes.pop(); |
| |
| } else { |
| // Multi-exit block, e.g. a switch statement |
| // But we don't need to do anything here |
| } |
| |
| } // End of for all blocks |
| |
| } |
| |
| |
| //------------------------------dump------------------------------------------- |
| #ifndef PRODUCT |
| void PhaseCFG::_dump_cfg( const Node *end, VectorSet &visited ) const { |
| const Node *x = end->is_block_proj(); |
| assert( x, "not a CFG" ); |
| |
| // Do not visit this block again |
| if( visited.test_set(x->_idx) ) return; |
| |
| // Skip through this block |
| const Node *p = x; |
| do { |
| p = p->in(0); // Move control forward |
| assert( !p->is_block_proj() || p->is_Root(), "not a CFG" ); |
| } while( !p->is_block_start() ); |
| |
| // Recursively visit |
| for( uint i=1; i<p->req(); i++ ) |
| _dump_cfg(p->in(i),visited); |
| |
| // Dump the block |
| _bbs[p->_idx]->dump(&_bbs); |
| } |
| |
| void PhaseCFG::dump( ) const { |
| tty->print("\n--- CFG --- %d BBs\n",_num_blocks); |
| if( _blocks.size() ) { // Did we do basic-block layout? |
| for( uint i=0; i<_num_blocks; i++ ) |
| _blocks[i]->dump(&_bbs); |
| } else { // Else do it with a DFS |
| VectorSet visited(_bbs._arena); |
| _dump_cfg(_root,visited); |
| } |
| } |
| |
| void PhaseCFG::dump_headers() { |
| for( uint i = 0; i < _num_blocks; i++ ) { |
| if( _blocks[i] == NULL ) continue; |
| _blocks[i]->dump_head(&_bbs); |
| } |
| } |
| |
| void PhaseCFG::verify( ) const { |
| // Verify sane CFG |
| for( uint i = 0; i < _num_blocks; i++ ) { |
| Block *b = _blocks[i]; |
| uint cnt = b->_nodes.size(); |
| uint j; |
| for( j = 0; j < cnt; j++ ) { |
| Node *n = b->_nodes[j]; |
| assert( _bbs[n->_idx] == b, "" ); |
| if( j >= 1 && n->is_Mach() && |
| n->as_Mach()->ideal_Opcode() == Op_CreateEx ) { |
| assert( j == 1 || b->_nodes[j-1]->is_Phi(), |
| "CreateEx must be first instruction in block" ); |
| } |
| for( uint k = 0; k < n->req(); k++ ) { |
| Node *use = n->in(k); |
| if( use && use != n ) { |
| assert( _bbs[use->_idx] || use->is_Con(), |
| "must have block; constants for debug info ok" ); |
| } |
| } |
| } |
| |
| j = b->end_idx(); |
| Node *bp = (Node*)b->_nodes[b->_nodes.size()-1]->is_block_proj(); |
| assert( bp, "last instruction must be a block proj" ); |
| assert( bp == b->_nodes[j], "wrong number of successors for this block" ); |
| if( bp->is_Catch() ) { |
| while( b->_nodes[--j]->Opcode() == Op_MachProj ) ; |
| assert( b->_nodes[j]->is_Call(), "CatchProj must follow call" ); |
| } |
| else if( bp->is_Mach() && bp->as_Mach()->ideal_Opcode() == Op_If ) { |
| assert( b->_num_succs == 2, "Conditional branch must have two targets"); |
| } |
| } |
| } |
| #endif |
| |
| //============================================================================= |
| //------------------------------UnionFind-------------------------------------- |
| UnionFind::UnionFind( uint max ) : _cnt(max), _max(max), _indices(NEW_RESOURCE_ARRAY(uint,max)) { |
| Copy::zero_to_bytes( _indices, sizeof(uint)*max ); |
| } |
| |
| void UnionFind::extend( uint from_idx, uint to_idx ) { |
| _nesting.check(); |
| if( from_idx >= _max ) { |
| uint size = 16; |
| while( size <= from_idx ) size <<=1; |
| _indices = REALLOC_RESOURCE_ARRAY( uint, _indices, _max, size ); |
| _max = size; |
| } |
| while( _cnt <= from_idx ) _indices[_cnt++] = 0; |
| _indices[from_idx] = to_idx; |
| } |
| |
| void UnionFind::reset( uint max ) { |
| assert( max <= max_uint, "Must fit within uint" ); |
| // Force the Union-Find mapping to be at least this large |
| extend(max,0); |
| // Initialize to be the ID mapping. |
| for( uint i=0; i<_max; i++ ) map(i,i); |
| } |
| |
| //------------------------------Find_compress---------------------------------- |
| // Straight out of Tarjan's union-find algorithm |
| uint UnionFind::Find_compress( uint idx ) { |
| uint cur = idx; |
| uint next = lookup(cur); |
| while( next != cur ) { // Scan chain of equivalences |
| assert( next < cur, "always union smaller" ); |
| cur = next; // until find a fixed-point |
| next = lookup(cur); |
| } |
| // Core of union-find algorithm: update chain of |
| // equivalences to be equal to the root. |
| while( idx != next ) { |
| uint tmp = lookup(idx); |
| map(idx, next); |
| idx = tmp; |
| } |
| return idx; |
| } |
| |
| //------------------------------Find_const------------------------------------- |
| // Like Find above, but no path compress, so bad asymptotic behavior |
| uint UnionFind::Find_const( uint idx ) const { |
| if( idx == 0 ) return idx; // Ignore the zero idx |
| // Off the end? This can happen during debugging dumps |
| // when data structures have not finished being updated. |
| if( idx >= _max ) return idx; |
| uint next = lookup(idx); |
| while( next != idx ) { // Scan chain of equivalences |
| assert( next < idx, "always union smaller" ); |
| idx = next; // until find a fixed-point |
| next = lookup(idx); |
| } |
| return next; |
| } |
| |
| //------------------------------Union------------------------------------------ |
| // union 2 sets together. |
| void UnionFind::Union( uint idx1, uint idx2 ) { |
| uint src = Find(idx1); |
| uint dst = Find(idx2); |
| assert( src, "" ); |
| assert( dst, "" ); |
| assert( src < _max, "oob" ); |
| assert( dst < _max, "oob" ); |
| assert( src < dst, "always union smaller" ); |
| map(dst,src); |
| } |