diff -r fd16c54261b3 -r 489c9b5090e2 hotspot/src/share/vm/opto/block.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/hotspot/src/share/vm/opto/block.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,952 @@ +/* + * 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_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_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_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; idump(); + 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 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]; + // 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); + // 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; ireq(); 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); +}