| /* |
| * Copyright (c) 1997, 2014, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "libadt/vectset.hpp" |
| #include "memory/allocation.inline.hpp" |
| #include "opto/block.hpp" |
| #include "opto/cfgnode.hpp" |
| #include "opto/chaitin.hpp" |
| #include "opto/loopnode.hpp" |
| #include "opto/machnode.hpp" |
| #include "opto/matcher.hpp" |
| #include "opto/opcodes.hpp" |
| #include "opto/rootnode.hpp" |
| #include "utilities/copy.hpp" |
| |
| 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; |
| } |
| |
| #ifndef PRODUCT |
| void Block_List::print() { |
| for (uint i=0; i < size(); i++) { |
| tty->print("B%d ", _blocks[i]->_pre_order); |
| } |
| tty->print("size = %d\n", size()); |
| } |
| #endif |
| |
| 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 |
| if (has_loop_alignment()) return loop_alignment(); |
| |
| return relocInfo::addr_unit(); // no particular alignment |
| } |
| |
| uint Block::compute_loop_alignment() { |
| Node *h = head(); |
| int unit_sz = relocInfo::addr_unit(); |
| 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*unit_sz) ? (OptoLoopAlignment>>2) : unit_sz; |
| } |
| // 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 unit_sz; // Loop does not loop, more often than not! |
| } |
| return OptoLoopAlignment; // Otherwise align loop head |
| } |
| |
| return unit_sz; // 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. Stop, and return 0 if sum_size |
| // exceeds OptoLoopAlignment. |
| uint Block::compute_first_inst_size(uint& sum_size, uint inst_cnt, |
| PhaseRegAlloc* ra) { |
| uint last_inst = number_of_nodes(); |
| for( uint j = 0; j < last_inst && inst_cnt > 0; j++ ) { |
| uint inst_size = get_node(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 < number_of_nodes(); i++ ) { |
| if( get_node(i) == n ) |
| return i; |
| } |
| ShouldNotReachHere(); |
| return 0; |
| } |
| |
| // Find and remove n from block list |
| void Block::find_remove( const Node *n ) { |
| remove_node(find_node(n)); |
| } |
| |
| bool Block::contains(const Node *n) const { |
| return _nodes.contains(n); |
| } |
| |
| // 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 = number_of_nodes() - 1; |
| |
| // Check for ending goto |
| if ((end_idx > 0) && (get_node(end_idx)->is_MachGoto())) { |
| 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) && !get_node(end_idx)->is_Mach()) { |
| end_idx--; |
| } |
| |
| // No room for any interesting instructions? |
| if (end_idx == 0) { |
| return success_result; |
| } |
| |
| return not_empty; |
| } |
| |
| // Return true if the block's code implies that it is 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_MachGoto()) |
| en = en->in(0); |
| if (en->is_Catch()) |
| en = en->in(0); |
| if (en->is_MachProj() && 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; |
| } |
| |
| // True if block is low enough frequency or guarded by a test which |
| // mostly does not go here. |
| bool PhaseCFG::is_uncommon(const Block* block) { |
| // Initial blocks must never be moved, so are never uncommon. |
| if (block->head()->is_Root() || block->head()->is_Start()) return false; |
| |
| // Check for way-low freq |
| if(block->_freq < BLOCK_FREQUENCY(0.00001f) ) return true; |
| |
| // Look for code shape indicating uncommon_trap or slow path |
| if (block->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< block->num_preds(); i++ ) { |
| Block* guard = get_block_for_node(block->pred(i)); |
| // 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(block->_freq < guard->_freq * guard_factor ) { |
| uncommon_for_freq_preds++; |
| } |
| } |
| } |
| if( block->num_preds() > 1 && |
| // The block is uncommon if all preds are uncommon or |
| (uncommon_preds == (block->num_preds()-1) || |
| // it is uncommon for all frequent preds. |
| uncommon_for_freq_preds == freq_preds) ) { |
| return true; |
| } |
| return false; |
| } |
| |
| #ifndef PRODUCT |
| void Block::dump_bidx(const Block* orig, outputStream* st) const { |
| if (_pre_order) st->print("B%d",_pre_order); |
| else st->print("N%d", head()->_idx); |
| |
| if (Verbose && orig != this) { |
| // Dump the original block's idx |
| st->print(" ("); |
| orig->dump_bidx(orig, st); |
| st->print(")"); |
| } |
| } |
| |
| void Block::dump_pred(const PhaseCFG* cfg, Block* orig, outputStream* st) const { |
| if (is_connector()) { |
| for (uint i=1; i<num_preds(); i++) { |
| Block *p = cfg->get_block_for_node(pred(i)); |
| p->dump_pred(cfg, orig, st); |
| } |
| } else { |
| dump_bidx(orig, st); |
| st->print(" "); |
| } |
| } |
| |
| void Block::dump_head(const PhaseCFG* cfg, outputStream* st) const { |
| // Print the basic block |
| dump_bidx(this, st); |
| st->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], st); |
| st->print(" "); |
| } |
| st->print("<- "); |
| if( head()->is_block_start() ) { |
| for (uint i=1; i<num_preds(); i++) { |
| Node *s = pred(i); |
| if (cfg != NULL) { |
| Block *p = cfg->get_block_for_node(s); |
| p->dump_pred(cfg, p, st); |
| } else { |
| while (!s->is_block_start()) |
| s = s->in(0); |
| st->print("N%d ", s->_idx ); |
| } |
| } |
| } else { |
| st->print("BLOCK HEAD IS JUNK "); |
| } |
| |
| // Print loop, if any |
| const Block *bhead = this; // Head of self-loop |
| Node *bh = bhead->head(); |
| |
| if ((cfg != NULL) && bh->is_Loop() && !head()->is_Root()) { |
| LoopNode *loop = bh->as_Loop(); |
| const Block *bx = cfg->get_block_for_node(loop->in(LoopNode::LoopBackControl)); |
| while (bx->is_connector()) { |
| bx = cfg->get_block_for_node(bx->pred(1)); |
| } |
| st->print("\tLoop: B%d-B%d ", bhead->_pre_order, bx->_pre_order); |
| // Dump any loop-specific bits, especially for CountedLoops. |
| loop->dump_spec(st); |
| } else if (has_loop_alignment()) { |
| st->print(" top-of-loop"); |
| } |
| st->print(" Freq: %g",_freq); |
| if( Verbose || WizardMode ) { |
| st->print(" IDom: %d/#%d", _idom ? _idom->_pre_order : 0, _dom_depth); |
| st->print(" RegPressure: %d",_reg_pressure); |
| st->print(" IHRP Index: %d",_ihrp_index); |
| st->print(" FRegPressure: %d",_freg_pressure); |
| st->print(" FHRP Index: %d",_fhrp_index); |
| } |
| st->cr(); |
| } |
| |
| void Block::dump() const { |
| dump(NULL); |
| } |
| |
| void Block::dump(const PhaseCFG* cfg) const { |
| dump_head(cfg); |
| for (uint i=0; i< number_of_nodes(); i++) { |
| get_node(i)->dump(); |
| } |
| tty->print("\n"); |
| } |
| #endif |
| |
| PhaseCFG::PhaseCFG(Arena* arena, RootNode* root, Matcher& matcher) |
| : Phase(CFG) |
| , _block_arena(arena) |
| , _root(root) |
| , _matcher(matcher) |
| , _node_to_block_mapping(arena) |
| , _node_latency(NULL) |
| #ifndef PRODUCT |
| , _trace_opto_pipelining(TraceOptoPipelining || C->method_has_option("TraceOptoPipelining")) |
| #endif |
| #ifdef ASSERT |
| , _raw_oops(arena) |
| #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) GotoNode(NULL); |
| x->init_req(0, x); |
| _goto = matcher.match_tree(x); |
| assert(_goto != NULL, ""); |
| _goto->set_req(0,_goto); |
| |
| // Build the CFG in Reverse Post Order |
| _number_of_blocks = build_cfg(); |
| _root_block = get_block_for_node(_root); |
| } |
| |
| // 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->live_nodes() >> 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) 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 (_block_arena) Block(_block_arena, p); |
| map_node_to_block(p, bb); |
| map_node_to_block(x, bb); |
| if( x != p ) { // Only for root is x == p |
| bb->push_node((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 = get_block_for_node(x); |
| // Insert into nodes array, if not already there |
| if (!has_block(proj)) { |
| assert( x != proj, "" ); |
| // Map basic block of projection |
| map_node_to_block(proj, pb); |
| pb->push_node(proj); |
| } |
| // Insert self as a child of my predecessor block |
| pb->_succs.map(pb->_num_succs++, get_block_for_node(np)); |
| assert( pb->get_node(pb->number_of_nodes() - 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; |
| } |
| |
| // 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 < number_of_blocks(), "illegal block number"); |
| Block* in = get_block(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->get_node(in->number_of_nodes() - in->_num_succs + succ_no)->as_Proj(); |
| // create region for basic block |
| RegionNode* region = new (C) RegionNode(2); |
| region->init_req(1, proj); |
| // setup corresponding basic block |
| Block* block = new (_block_arena) Block(_block_arena, region); |
| map_node_to_block(region, 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->push_node(gto); |
| map_node_to_block(gto, 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 |
| add_block_at(block_no + 1, block); |
| } |
| |
| // 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->number_of_nodes() - b->_num_succs-1; |
| if (branch_idx < 1) { |
| return false; |
| } |
| Node *branch = b->get_node(branch_idx); |
| if (branch->is_Catch()) { |
| return true; |
| } |
| if (branch->is_Mach()) { |
| if (branch->is_MachNullCheck()) { |
| return true; |
| } |
| int iop = branch->as_Mach()->ideal_Opcode(); |
| if (iop == Op_FastLock || iop == Op_FastUnlock) { |
| return true; |
| } |
| // Don't flip if branch has an implicit check. |
| if (branch->as_Mach()->is_TrapBasedCheckNode()) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| // 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->get_node(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->get_node(end_idx); |
| b->map_node(gto, end_idx); // Slam over NeverBranch |
| map_node_to_block(gto, b); |
| C->regalloc()->set_bad(gto->_idx); |
| b->pop_node(); // Yank projections |
| b->pop_node(); // 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->get_node(k)->is_Phi(); k++ ) |
| dead->get_node(k)->del_req(j); |
| } |
| |
| // Helper function to move block bx to the slot following b_index. Return |
| // true if the move is successful, otherwise false |
| bool PhaseCFG::move_to_next(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) && (get_block(bx_index) == bx)) { |
| return false; |
| } |
| |
| // Find the current index of block bx on the block list |
| bx_index = b_index + 1; |
| while (bx_index < number_of_blocks() && get_block(bx_index) != bx) { |
| bx_index++; |
| } |
| assert(get_block(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 = get_block_for_node(bx->pred(k)); |
| if (pred == get_block(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; |
| } |
| |
| // Move empty and uncommon blocks to the end. |
| void PhaseCFG::move_to_end(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->pop_node(); |
| } |
| // 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); |
| } |
| |
| // Set loop alignment for every block |
| void PhaseCFG::set_loop_alignment() { |
| uint last = number_of_blocks(); |
| assert(get_block(0) == get_root_block(), ""); |
| |
| for (uint i = 1; i < last; i++) { |
| Block* block = get_block(i); |
| if (block->head()->is_Loop()) { |
| block->set_loop_alignment(block); |
| } |
| } |
| } |
| |
| // Make empty basic blocks to be "connector" blocks, Move uncommon blocks |
| // to the end. |
| void PhaseCFG::remove_empty_blocks() { |
| // Move uncommon blocks to the end |
| uint last = number_of_blocks(); |
| assert(get_block(0) == get_root_block(), ""); |
| |
| for (uint i = 1; i < last; i++) { |
| Block* block = get_block(i); |
| if (block->is_connector()) { |
| break; |
| } |
| |
| // 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 (block->get_node(block->end_idx())->Opcode() == Op_NeverBranch) { |
| convert_NeverBranch_to_Goto(block); |
| } |
| |
| // Look for uncommon blocks and move to end. |
| if (!C->do_freq_based_layout()) { |
| if (is_uncommon(block)) { |
| move_to_end(block, i); |
| last--; // No longer check for being uncommon! |
| if (no_flip_branch(block)) { // Fall-thru case must follow? |
| // Find the fall-thru block |
| block = get_block(i); |
| move_to_end(block, i); |
| last--; |
| } |
| // backup block counter post-increment |
| i--; |
| } |
| } |
| } |
| |
| // Move empty blocks to the end |
| last = number_of_blocks(); |
| for (uint i = 1; i < last; i++) { |
| Block* block = get_block(i); |
| if (block->is_Empty() != Block::not_empty) { |
| move_to_end(block, i); |
| last--; |
| i--; |
| } |
| } // End of for all blocks |
| } |
| |
| Block *PhaseCFG::fixup_trap_based_check(Node *branch, Block *block, int block_pos, Block *bnext) { |
| // Trap based checks must fall through to the successor with |
| // PROB_ALWAYS. |
| // They should be an If with 2 successors. |
| assert(branch->is_MachIf(), "must be If"); |
| assert(block->_num_succs == 2, "must have 2 successors"); |
| |
| // Get the If node and the projection for the first successor. |
| MachIfNode *iff = block->get_node(block->number_of_nodes()-3)->as_MachIf(); |
| ProjNode *proj0 = block->get_node(block->number_of_nodes()-2)->as_Proj(); |
| ProjNode *proj1 = block->get_node(block->number_of_nodes()-1)->as_Proj(); |
| ProjNode *projt = (proj0->Opcode() == Op_IfTrue) ? proj0 : proj1; |
| ProjNode *projf = (proj0->Opcode() == Op_IfFalse) ? proj0 : proj1; |
| |
| // Assert that proj0 and succs[0] match up. Similarly for proj1 and succs[1]. |
| assert(proj0->raw_out(0) == block->_succs[0]->head(), "Mismatch successor 0"); |
| assert(proj1->raw_out(0) == block->_succs[1]->head(), "Mismatch successor 1"); |
| |
| ProjNode *proj_always; |
| ProjNode *proj_never; |
| // We must negate the branch if the implicit check doesn't follow |
| // the branch's TRUE path. Then, the new TRUE branch target will |
| // be the old FALSE branch target. |
| if (iff->_prob <= 2*PROB_NEVER) { // There are small rounding errors. |
| proj_never = projt; |
| proj_always = projf; |
| } else { |
| // We must negate the branch if the trap doesn't follow the |
| // branch's TRUE path. Then, the new TRUE branch target will |
| // be the old FALSE branch target. |
| proj_never = projf; |
| proj_always = projt; |
| iff->negate(); |
| } |
| assert(iff->_prob <= 2*PROB_NEVER, "Trap based checks are expected to trap never!"); |
| // Map the successors properly |
| block->_succs.map(0, get_block_for_node(proj_never ->raw_out(0))); // The target of the trap. |
| block->_succs.map(1, get_block_for_node(proj_always->raw_out(0))); // The fall through target. |
| |
| if (block->get_node(block->number_of_nodes() - block->_num_succs + 1) != proj_always) { |
| block->map_node(proj_never, block->number_of_nodes() - block->_num_succs + 0); |
| block->map_node(proj_always, block->number_of_nodes() - block->_num_succs + 1); |
| } |
| |
| // Place the fall through block after this block. |
| Block *bs1 = block->non_connector_successor(1); |
| if (bs1 != bnext && move_to_next(bs1, block_pos)) { |
| bnext = bs1; |
| } |
| // If the fall through block still is not the next block, insert a goto. |
| if (bs1 != bnext) { |
| insert_goto_at(block_pos, 1); |
| } |
| return bnext; |
| } |
| |
| // Fix up the final control flow for basic blocks. |
| void PhaseCFG::fixup_flow() { |
| // Fixup final control flow for the blocks. Remove jump-to-next |
| // block. If neither arm of an 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 (uint i = 0; i < number_of_blocks(); i++) { |
| Block* block = get_block(i); |
| block->_pre_order = i; // turn pre-order into block-index |
| |
| // Connector blocks need no further processing. |
| if (block->is_connector()) { |
| assert((i+1) == number_of_blocks() || get_block(i + 1)->is_connector(), "All connector blocks should sink to the end"); |
| continue; |
| } |
| assert(block->is_Empty() != Block::completely_empty, "Empty blocks should be connectors"); |
| |
| Block* bnext = (i < number_of_blocks() - 1) ? get_block(i + 1) : NULL; |
| Block* bs0 = block->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(block)) { |
| // Find fall through case - if must fall into its target. |
| // Get the index of the branch's first successor. |
| int branch_idx = block->number_of_nodes() - block->_num_succs; |
| |
| // The branch is 1 before the branch's first successor. |
| Node *branch = block->get_node(branch_idx-1); |
| |
| // Handle no-flip branches which have implicit checks and which require |
| // special block ordering and individual semantics of the 'fall through |
| // case'. |
| if ((TrapBasedNullChecks || TrapBasedRangeChecks) && |
| branch->is_Mach() && branch->as_Mach()->is_TrapBasedCheckNode()) { |
| bnext = fixup_trap_based_check(branch, block, i, bnext); |
| } else { |
| // Else, default handling for no-flip branches |
| for (uint j2 = 0; j2 < block->_num_succs; j2++) { |
| const ProjNode* p = block->get_node(branch_idx + j2)->as_Proj(); |
| if (p->_con == 0) { |
| // successor j2 is fall through case |
| if (block->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 && block->_num_succs == 2) { |
| // Flip targets in succs map |
| Block *tbs0 = block->_succs[0]; |
| Block *tbs1 = block->_succs[1]; |
| block->_succs.map(0, tbs1); |
| block->_succs.map(1, tbs0); |
| } |
| break; |
| } |
| } |
| } |
| |
| // Remove all CatchProjs |
| for (uint j = 0; j < block->_num_succs; j++) { |
| block->pop_node(); |
| } |
| |
| } else if (block->_num_succs == 1) { |
| // Block ends in a Goto? |
| if (bnext == bs0) { |
| // We fall into next block; remove the Goto |
| block->pop_node(); |
| } |
| |
| } else if(block->_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 = block->get_node(block->number_of_nodes() - 3)->as_Mach(); |
| ProjNode* proj0 = block->get_node(block->number_of_nodes() - 2)->as_Proj(); |
| ProjNode* proj1 = block->get_node(block->number_of_nodes() - 1)->as_Proj(); |
| |
| // Assert that proj0 and succs[0] match up. Similarly for proj1 and succs[1]. |
| assert(proj0->raw_out(0) == block->_succs[0]->head(), "Mismatch successor 0"); |
| assert(proj1->raw_out(0) == block->_succs[1]->head(), "Mismatch successor 1"); |
| |
| Block* bs1 = block->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 (!C->do_freq_based_layout() && 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 (move_to_next(bx, i)) { |
| bnext = bx; |
| } else if (move_to_next(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 = block->_succs[0]; |
| Block* tbs1 = block->_succs[1]; |
| block->_succs.map(0, tbs1); |
| block->_succs.map(1, tbs0); |
| // Flip projection for each target |
| ProjNode* tmp = proj0; |
| proj0 = proj1; |
| proj1 = tmp; |
| |
| } else if(bnext != bs1) { |
| // 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->as_MachIf()->negate(); |
| } |
| |
| block->pop_node(); // Remove IfFalse & IfTrue projections |
| block->pop_node(); |
| |
| } else { |
| // Multi-exit block, e.g. a switch statement |
| // But we don't need to do anything here |
| } |
| } // End of for all blocks |
| } |
| |
| |
| // postalloc_expand: Expand nodes after register allocation. |
| // |
| // postalloc_expand has to be called after register allocation, just |
| // before output (i.e. scheduling). It only gets called if |
| // Matcher::require_postalloc_expand is true. |
| // |
| // Background: |
| // |
| // Nodes that are expandend (one compound node requiring several |
| // assembler instructions to be implemented split into two or more |
| // non-compound nodes) after register allocation are not as nice as |
| // the ones expanded before register allocation - they don't |
| // participate in optimizations as global code motion. But after |
| // register allocation we can expand nodes that use registers which |
| // are not spillable or registers that are not allocated, because the |
| // old compound node is simply replaced (in its location in the basic |
| // block) by a new subgraph which does not contain compound nodes any |
| // more. The scheduler called during output can later on process these |
| // non-compound nodes. |
| // |
| // Implementation: |
| // |
| // Nodes requiring postalloc expand are specified in the ad file by using |
| // a postalloc_expand statement instead of ins_encode. A postalloc_expand |
| // contains a single call to an encoding, as does an ins_encode |
| // statement. Instead of an emit() function a postalloc_expand() function |
| // is generated that doesn't emit assembler but creates a new |
| // subgraph. The code below calls this postalloc_expand function for each |
| // node with the appropriate attribute. This function returns the new |
| // nodes generated in an array passed in the call. The old node, |
| // potential MachTemps before and potential Projs after it then get |
| // disconnected and replaced by the new nodes. The instruction |
| // generating the result has to be the last one in the array. In |
| // general it is assumed that Projs after the node expanded are |
| // kills. These kills are not required any more after expanding as |
| // there are now explicitly visible def-use chains and the Projs are |
| // removed. This does not hold for calls: They do not only have |
| // kill-Projs but also Projs defining values. Therefore Projs after |
| // the node expanded are removed for all but for calls. If a node is |
| // to be reused, it must be added to the nodes list returned, and it |
| // will be added again. |
| // |
| // Implementing the postalloc_expand function for a node in an enc_class |
| // is rather tedious. It requires knowledge about many node details, as |
| // the nodes and the subgraph must be hand crafted. To simplify this, |
| // adlc generates some utility variables into the postalloc_expand function, |
| // e.g., holding the operands as specified by the postalloc_expand encoding |
| // specification, e.g.: |
| // * unsigned idx_<par_name> holding the index of the node in the ins |
| // * Node *n_<par_name> holding the node loaded from the ins |
| // * MachOpnd *op_<par_name> holding the corresponding operand |
| // |
| // The ordering of operands can not be determined by looking at a |
| // rule. Especially if a match rule matches several different trees, |
| // several nodes are generated from one instruct specification with |
| // different operand orderings. In this case the adlc generated |
| // variables are the only way to access the ins and operands |
| // deterministically. |
| // |
| // If assigning a register to a node that contains an oop, don't |
| // forget to call ra_->set_oop() for the node. |
| void PhaseCFG::postalloc_expand(PhaseRegAlloc* _ra) { |
| GrowableArray <Node *> new_nodes(32); // Array with new nodes filled by postalloc_expand function of node. |
| GrowableArray <Node *> remove(32); |
| GrowableArray <Node *> succs(32); |
| unsigned int max_idx = C->unique(); // Remember to distinguish new from old nodes. |
| DEBUG_ONLY(bool foundNode = false); |
| |
| // for all blocks |
| for (uint i = 0; i < number_of_blocks(); i++) { |
| Block *b = _blocks[i]; |
| // For all instructions in the current block. |
| for (uint j = 0; j < b->number_of_nodes(); j++) { |
| Node *n = b->get_node(j); |
| if (n->is_Mach() && n->as_Mach()->requires_postalloc_expand()) { |
| #ifdef ASSERT |
| if (TracePostallocExpand) { |
| if (!foundNode) { |
| foundNode = true; |
| tty->print("POSTALLOC EXPANDING %d %s\n", C->compile_id(), |
| C->method() ? C->method()->name()->as_utf8() : C->stub_name()); |
| } |
| tty->print(" postalloc expanding "); n->dump(); |
| if (Verbose) { |
| tty->print(" with ins:\n"); |
| for (uint k = 0; k < n->len(); ++k) { |
| if (n->in(k)) { tty->print(" "); n->in(k)->dump(); } |
| } |
| } |
| } |
| #endif |
| new_nodes.clear(); |
| // Collect nodes that have to be removed from the block later on. |
| uint req = n->req(); |
| remove.clear(); |
| for (uint k = 0; k < req; ++k) { |
| if (n->in(k) && n->in(k)->is_MachTemp()) { |
| remove.push(n->in(k)); // MachTemps which are inputs to the old node have to be removed. |
| n->in(k)->del_req(0); |
| j--; |
| } |
| } |
| |
| // Check whether we can allocate enough nodes. We set a fix limit for |
| // the size of postalloc expands with this. |
| uint unique_limit = C->unique() + 40; |
| if (unique_limit >= _ra->node_regs_max_index()) { |
| Compile::current()->record_failure("out of nodes in postalloc expand"); |
| return; |
| } |
| |
| // Emit (i.e. generate new nodes). |
| n->as_Mach()->postalloc_expand(&new_nodes, _ra); |
| |
| assert(C->unique() < unique_limit, "You allocated too many nodes in your postalloc expand."); |
| |
| // Disconnect the inputs of the old node. |
| // |
| // We reuse MachSpillCopy nodes. If we need to expand them, there |
| // are many, so reusing pays off. If reused, the node already |
| // has the new ins. n must be the last node on new_nodes list. |
| if (!n->is_MachSpillCopy()) { |
| for (int k = req - 1; k >= 0; --k) { |
| n->del_req(k); |
| } |
| } |
| |
| #ifdef ASSERT |
| // Check that all nodes have proper operands. |
| for (int k = 0; k < new_nodes.length(); ++k) { |
| if (new_nodes.at(k)->_idx < max_idx || !new_nodes.at(k)->is_Mach()) continue; // old node, Proj ... |
| MachNode *m = new_nodes.at(k)->as_Mach(); |
| for (unsigned int l = 0; l < m->num_opnds(); ++l) { |
| if (MachOper::notAnOper(m->_opnds[l])) { |
| outputStream *os = tty; |
| os->print("Node %s ", m->Name()); |
| os->print("has invalid opnd %d: %p\n", l, m->_opnds[l]); |
| assert(0, "Invalid operands, see inline trace in hs_err_pid file."); |
| } |
| } |
| } |
| #endif |
| |
| // Collect succs of old node in remove (for projections) and in succs (for |
| // all other nodes) do _not_ collect projections in remove (but in succs) |
| // in case the node is a call. We need the projections for calls as they are |
| // associated with registes (i.e. they are defs). |
| succs.clear(); |
| for (DUIterator k = n->outs(); n->has_out(k); k++) { |
| if (n->out(k)->is_Proj() && !n->is_MachCall() && !n->is_MachBranch()) { |
| remove.push(n->out(k)); |
| } else { |
| succs.push(n->out(k)); |
| } |
| } |
| // Replace old node n as input of its succs by last of the new nodes. |
| for (int k = 0; k < succs.length(); ++k) { |
| Node *succ = succs.at(k); |
| for (uint l = 0; l < succ->req(); ++l) { |
| if (succ->in(l) == n) { |
| succ->set_req(l, new_nodes.at(new_nodes.length() - 1)); |
| } |
| } |
| for (uint l = succ->req(); l < succ->len(); ++l) { |
| if (succ->in(l) == n) { |
| succ->set_prec(l, new_nodes.at(new_nodes.length() - 1)); |
| } |
| } |
| } |
| |
| // Index of old node in block. |
| uint index = b->find_node(n); |
| // Insert new nodes into block and map them in nodes->blocks array |
| // and remember last node in n2. |
| Node *n2 = NULL; |
| for (int k = 0; k < new_nodes.length(); ++k) { |
| n2 = new_nodes.at(k); |
| b->insert_node(n2, ++index); |
| map_node_to_block(n2, b); |
| } |
| |
| // Add old node n to remove and remove them all from block. |
| remove.push(n); |
| j--; |
| #ifdef ASSERT |
| if (TracePostallocExpand && Verbose) { |
| tty->print(" removing:\n"); |
| for (int k = 0; k < remove.length(); ++k) { |
| tty->print(" "); remove.at(k)->dump(); |
| } |
| tty->print(" inserting:\n"); |
| for (int k = 0; k < new_nodes.length(); ++k) { |
| tty->print(" "); new_nodes.at(k)->dump(); |
| } |
| } |
| #endif |
| for (int k = 0; k < remove.length(); ++k) { |
| if (b->contains(remove.at(k))) { |
| b->find_remove(remove.at(k)); |
| } else { |
| assert(remove.at(k)->is_Proj() && (remove.at(k)->in(0)->is_MachBranch()), ""); |
| } |
| } |
| // If anything has been inserted (n2 != NULL), continue after last node inserted. |
| // This does not always work. Some postalloc expands don't insert any nodes, if they |
| // do optimizations (e.g., max(x,x)). In this case we decrement j accordingly. |
| j = n2 ? b->find_node(n2) : j; |
| } |
| } |
| } |
| |
| #ifdef ASSERT |
| if (foundNode) { |
| tty->print("FINISHED %d %s\n", C->compile_id(), |
| C->method() ? C->method()->name()->as_utf8() : C->stub_name()); |
| tty->flush(); |
| } |
| #endif |
| } |
| |
| |
| //------------------------------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 |
| get_block_for_node(p)->dump(this); |
| } |
| |
| void PhaseCFG::dump( ) const { |
| tty->print("\n--- CFG --- %d BBs\n", number_of_blocks()); |
| if (_blocks.size()) { // Did we do basic-block layout? |
| for (uint i = 0; i < number_of_blocks(); i++) { |
| const Block* block = get_block(i); |
| block->dump(this); |
| } |
| } else { // Else do it with a DFS |
| VectorSet visited(_block_arena); |
| _dump_cfg(_root,visited); |
| } |
| } |
| |
| void PhaseCFG::dump_headers() { |
| for (uint i = 0; i < number_of_blocks(); i++) { |
| Block* block = get_block(i); |
| if (block != NULL) { |
| block->dump_head(this); |
| } |
| } |
| } |
| |
| void PhaseCFG::verify() const { |
| #ifdef ASSERT |
| // Verify sane CFG |
| for (uint i = 0; i < number_of_blocks(); i++) { |
| Block* block = get_block(i); |
| uint cnt = block->number_of_nodes(); |
| uint j; |
| for (j = 0; j < cnt; j++) { |
| Node *n = block->get_node(j); |
| assert(get_block_for_node(n) == block, ""); |
| if (j >= 1 && n->is_Mach() && n->as_Mach()->ideal_Opcode() == Op_CreateEx) { |
| assert(j == 1 || block->get_node(j-1)->is_Phi(), "CreateEx must be first instruction in block"); |
| } |
| if (n->needs_anti_dependence_check()) { |
| verify_anti_dependences(block, n); |
| } |
| for (uint k = 0; k < n->req(); k++) { |
| Node *def = n->in(k); |
| if (def && def != n) { |
| assert(get_block_for_node(def) || def->is_Con(), "must have block; constants for debug info ok"); |
| // Verify that instructions in the block is in correct order. |
| // Uses must follow their definition if they are at the same block. |
| // Mostly done to check that MachSpillCopy nodes are placed correctly |
| // when CreateEx node is moved in build_ifg_physical(). |
| if (get_block_for_node(def) == block && !(block->head()->is_Loop() && n->is_Phi()) && |
| // See (+++) comment in reg_split.cpp |
| !(n->jvms() != NULL && n->jvms()->is_monitor_use(k))) { |
| bool is_loop = false; |
| if (n->is_Phi()) { |
| for (uint l = 1; l < def->req(); l++) { |
| if (n == def->in(l)) { |
| is_loop = true; |
| break; // Some kind of loop |
| } |
| } |
| } |
| assert(is_loop || block->find_node(def) < j, "uses must follow definitions"); |
| } |
| } |
| } |
| } |
| |
| j = block->end_idx(); |
| Node* bp = (Node*)block->get_node(block->number_of_nodes() - 1)->is_block_proj(); |
| assert(bp, "last instruction must be a block proj"); |
| assert(bp == block->get_node(j), "wrong number of successors for this block"); |
| if (bp->is_Catch()) { |
| while (block->get_node(--j)->is_MachProj()) { |
| ; |
| } |
| assert(block->get_node(j)->is_MachCall(), "CatchProj must follow call"); |
| } else if (bp->is_Mach() && bp->as_Mach()->ideal_Opcode() == Op_If) { |
| assert(block->_num_succs == 2, "Conditional branch must have two targets"); |
| } |
| } |
| #endif |
| } |
| #endif |
| |
| 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); |
| } |
| |
| // 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; |
| } |
| |
| // 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 |
| idx = next; // until find a fixed-point |
| next = lookup(idx); |
| } |
| return next; |
| } |
| |
| // 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); |
| } |
| |
| #ifndef PRODUCT |
| void Trace::dump( ) const { |
| tty->print_cr("Trace (freq %f)", first_block()->_freq); |
| for (Block *b = first_block(); b != NULL; b = next(b)) { |
| tty->print(" B%d", b->_pre_order); |
| if (b->head()->is_Loop()) { |
| tty->print(" (L%d)", b->compute_loop_alignment()); |
| } |
| if (b->has_loop_alignment()) { |
| tty->print(" (T%d)", b->code_alignment()); |
| } |
| } |
| tty->cr(); |
| } |
| |
| void CFGEdge::dump( ) const { |
| tty->print(" B%d --> B%d Freq: %f out:%3d%% in:%3d%% State: ", |
| from()->_pre_order, to()->_pre_order, freq(), _from_pct, _to_pct); |
| switch(state()) { |
| case connected: |
| tty->print("connected"); |
| break; |
| case open: |
| tty->print("open"); |
| break; |
| case interior: |
| tty->print("interior"); |
| break; |
| } |
| if (infrequent()) { |
| tty->print(" infrequent"); |
| } |
| tty->cr(); |
| } |
| #endif |
| |
| // Comparison function for edges |
| static int edge_order(CFGEdge **e0, CFGEdge **e1) { |
| float freq0 = (*e0)->freq(); |
| float freq1 = (*e1)->freq(); |
| if (freq0 != freq1) { |
| return freq0 > freq1 ? -1 : 1; |
| } |
| |
| int dist0 = (*e0)->to()->_rpo - (*e0)->from()->_rpo; |
| int dist1 = (*e1)->to()->_rpo - (*e1)->from()->_rpo; |
| |
| return dist1 - dist0; |
| } |
| |
| // Comparison function for edges |
| extern "C" int trace_frequency_order(const void *p0, const void *p1) { |
| Trace *tr0 = *(Trace **) p0; |
| Trace *tr1 = *(Trace **) p1; |
| Block *b0 = tr0->first_block(); |
| Block *b1 = tr1->first_block(); |
| |
| // The trace of connector blocks goes at the end; |
| // we only expect one such trace |
| if (b0->is_connector() != b1->is_connector()) { |
| return b1->is_connector() ? -1 : 1; |
| } |
| |
| // Pull more frequently executed blocks to the beginning |
| float freq0 = b0->_freq; |
| float freq1 = b1->_freq; |
| if (freq0 != freq1) { |
| return freq0 > freq1 ? -1 : 1; |
| } |
| |
| int diff = tr0->first_block()->_rpo - tr1->first_block()->_rpo; |
| |
| return diff; |
| } |
| |
| // Find edges of interest, i.e, those which can fall through. Presumes that |
| // edges which don't fall through are of low frequency and can be generally |
| // ignored. Initialize the list of traces. |
| void PhaseBlockLayout::find_edges() { |
| // Walk the blocks, creating edges and Traces |
| uint i; |
| Trace *tr = NULL; |
| for (i = 0; i < _cfg.number_of_blocks(); i++) { |
| Block* b = _cfg.get_block(i); |
| tr = new Trace(b, next, prev); |
| traces[tr->id()] = tr; |
| |
| // All connector blocks should be at the end of the list |
| if (b->is_connector()) break; |
| |
| // If this block and the next one have a one-to-one successor |
| // predecessor relationship, simply append the next block |
| int nfallthru = b->num_fall_throughs(); |
| while (nfallthru == 1 && |
| b->succ_fall_through(0)) { |
| Block *n = b->_succs[0]; |
| |
| // Skip over single-entry connector blocks, we don't want to |
| // add them to the trace. |
| while (n->is_connector() && n->num_preds() == 1) { |
| n = n->_succs[0]; |
| } |
| |
| // We see a merge point, so stop search for the next block |
| if (n->num_preds() != 1) break; |
| |
| i++; |
| assert(n = _cfg.get_block(i), "expecting next block"); |
| tr->append(n); |
| uf->map(n->_pre_order, tr->id()); |
| traces[n->_pre_order] = NULL; |
| nfallthru = b->num_fall_throughs(); |
| b = n; |
| } |
| |
| if (nfallthru > 0) { |
| // Create a CFGEdge for each outgoing |
| // edge that could be a fall-through. |
| for (uint j = 0; j < b->_num_succs; j++ ) { |
| if (b->succ_fall_through(j)) { |
| Block *target = b->non_connector_successor(j); |
| float freq = b->_freq * b->succ_prob(j); |
| int from_pct = (int) ((100 * freq) / b->_freq); |
| int to_pct = (int) ((100 * freq) / target->_freq); |
| edges->append(new CFGEdge(b, target, freq, from_pct, to_pct)); |
| } |
| } |
| } |
| } |
| |
| // Group connector blocks into one trace |
| for (i++; i < _cfg.number_of_blocks(); i++) { |
| Block *b = _cfg.get_block(i); |
| assert(b->is_connector(), "connector blocks at the end"); |
| tr->append(b); |
| uf->map(b->_pre_order, tr->id()); |
| traces[b->_pre_order] = NULL; |
| } |
| } |
| |
| // Union two traces together in uf, and null out the trace in the list |
| void PhaseBlockLayout::union_traces(Trace* updated_trace, Trace* old_trace) { |
| uint old_id = old_trace->id(); |
| uint updated_id = updated_trace->id(); |
| |
| uint lo_id = updated_id; |
| uint hi_id = old_id; |
| |
| // If from is greater than to, swap values to meet |
| // UnionFind guarantee. |
| if (updated_id > old_id) { |
| lo_id = old_id; |
| hi_id = updated_id; |
| |
| // Fix up the trace ids |
| traces[lo_id] = traces[updated_id]; |
| updated_trace->set_id(lo_id); |
| } |
| |
| // Union the lower with the higher and remove the pointer |
| // to the higher. |
| uf->Union(lo_id, hi_id); |
| traces[hi_id] = NULL; |
| } |
| |
| // Append traces together via the most frequently executed edges |
| void PhaseBlockLayout::grow_traces() { |
| // Order the edges, and drive the growth of Traces via the most |
| // frequently executed edges. |
| edges->sort(edge_order); |
| for (int i = 0; i < edges->length(); i++) { |
| CFGEdge *e = edges->at(i); |
| |
| if (e->state() != CFGEdge::open) continue; |
| |
| Block *src_block = e->from(); |
| Block *targ_block = e->to(); |
| |
| // Don't grow traces along backedges? |
| if (!BlockLayoutRotateLoops) { |
| if (targ_block->_rpo <= src_block->_rpo) { |
| targ_block->set_loop_alignment(targ_block); |
| continue; |
| } |
| } |
| |
| Trace *src_trace = trace(src_block); |
| Trace *targ_trace = trace(targ_block); |
| |
| // If the edge in question can join two traces at their ends, |
| // append one trace to the other. |
| if (src_trace->last_block() == src_block) { |
| if (src_trace == targ_trace) { |
| e->set_state(CFGEdge::interior); |
| if (targ_trace->backedge(e)) { |
| // Reset i to catch any newly eligible edge |
| // (Or we could remember the first "open" edge, and reset there) |
| i = 0; |
| } |
| } else if (targ_trace->first_block() == targ_block) { |
| e->set_state(CFGEdge::connected); |
| src_trace->append(targ_trace); |
| union_traces(src_trace, targ_trace); |
| } |
| } |
| } |
| } |
| |
| // Embed one trace into another, if the fork or join points are sufficiently |
| // balanced. |
| void PhaseBlockLayout::merge_traces(bool fall_thru_only) { |
| // Walk the edge list a another time, looking at unprocessed edges. |
| // Fold in diamonds |
| for (int i = 0; i < edges->length(); i++) { |
| CFGEdge *e = edges->at(i); |
| |
| if (e->state() != CFGEdge::open) continue; |
| if (fall_thru_only) { |
| if (e->infrequent()) continue; |
| } |
| |
| Block *src_block = e->from(); |
| Trace *src_trace = trace(src_block); |
| bool src_at_tail = src_trace->last_block() == src_block; |
| |
| Block *targ_block = e->to(); |
| Trace *targ_trace = trace(targ_block); |
| bool targ_at_start = targ_trace->first_block() == targ_block; |
| |
| if (src_trace == targ_trace) { |
| // This may be a loop, but we can't do much about it. |
| e->set_state(CFGEdge::interior); |
| continue; |
| } |
| |
| if (fall_thru_only) { |
| // If the edge links the middle of two traces, we can't do anything. |
| // Mark the edge and continue. |
| if (!src_at_tail & !targ_at_start) { |
| continue; |
| } |
| |
| // Don't grow traces along backedges? |
| if (!BlockLayoutRotateLoops && (targ_block->_rpo <= src_block->_rpo)) { |
| continue; |
| } |
| |
| // If both ends of the edge are available, why didn't we handle it earlier? |
| assert(src_at_tail ^ targ_at_start, "Should have caught this edge earlier."); |
| |
| if (targ_at_start) { |
| // Insert the "targ" trace in the "src" trace if the insertion point |
| // is a two way branch. |
| // Better profitability check possible, but may not be worth it. |
| // Someday, see if the this "fork" has an associated "join"; |
| // then make a policy on merging this trace at the fork or join. |
| // For example, other things being equal, it may be better to place this |
| // trace at the join point if the "src" trace ends in a two-way, but |
| // the insertion point is one-way. |
| assert(src_block->num_fall_throughs() == 2, "unexpected diamond"); |
| e->set_state(CFGEdge::connected); |
| src_trace->insert_after(src_block, targ_trace); |
| union_traces(src_trace, targ_trace); |
| } else if (src_at_tail) { |
| if (src_trace != trace(_cfg.get_root_block())) { |
| e->set_state(CFGEdge::connected); |
| targ_trace->insert_before(targ_block, src_trace); |
| union_traces(targ_trace, src_trace); |
| } |
| } |
| } else if (e->state() == CFGEdge::open) { |
| // Append traces, even without a fall-thru connection. |
| // But leave root entry at the beginning of the block list. |
| if (targ_trace != trace(_cfg.get_root_block())) { |
| e->set_state(CFGEdge::connected); |
| src_trace->append(targ_trace); |
| union_traces(src_trace, targ_trace); |
| } |
| } |
| } |
| } |
| |
| // Order the sequence of the traces in some desirable way, and fixup the |
| // jumps at the end of each block. |
| void PhaseBlockLayout::reorder_traces(int count) { |
| ResourceArea *area = Thread::current()->resource_area(); |
| Trace ** new_traces = NEW_ARENA_ARRAY(area, Trace *, count); |
| Block_List worklist; |
| int new_count = 0; |
| |
| // Compact the traces. |
| for (int i = 0; i < count; i++) { |
| Trace *tr = traces[i]; |
| if (tr != NULL) { |
| new_traces[new_count++] = tr; |
| } |
| } |
| |
| // The entry block should be first on the new trace list. |
| Trace *tr = trace(_cfg.get_root_block()); |
| assert(tr == new_traces[0], "entry trace misplaced"); |
| |
| // Sort the new trace list by frequency |
| qsort(new_traces + 1, new_count - 1, sizeof(new_traces[0]), trace_frequency_order); |
| |
| // Patch up the successor blocks |
| _cfg.clear_blocks(); |
| for (int i = 0; i < new_count; i++) { |
| Trace *tr = new_traces[i]; |
| if (tr != NULL) { |
| tr->fixup_blocks(_cfg); |
| } |
| } |
| } |
| |
| // Order basic blocks based on frequency |
| PhaseBlockLayout::PhaseBlockLayout(PhaseCFG &cfg) |
| : Phase(BlockLayout) |
| , _cfg(cfg) { |
| ResourceMark rm; |
| ResourceArea *area = Thread::current()->resource_area(); |
| |
| // List of traces |
| int size = _cfg.number_of_blocks() + 1; |
| traces = NEW_ARENA_ARRAY(area, Trace *, size); |
| memset(traces, 0, size*sizeof(Trace*)); |
| next = NEW_ARENA_ARRAY(area, Block *, size); |
| memset(next, 0, size*sizeof(Block *)); |
| prev = NEW_ARENA_ARRAY(area, Block *, size); |
| memset(prev , 0, size*sizeof(Block *)); |
| |
| // List of edges |
| edges = new GrowableArray<CFGEdge*>; |
| |
| // Mapping block index --> block_trace |
| uf = new UnionFind(size); |
| uf->reset(size); |
| |
| // Find edges and create traces. |
| find_edges(); |
| |
| // Grow traces at their ends via most frequent edges. |
| grow_traces(); |
| |
| // Merge one trace into another, but only at fall-through points. |
| // This may make diamonds and other related shapes in a trace. |
| merge_traces(true); |
| |
| // Run merge again, allowing two traces to be catenated, even if |
| // one does not fall through into the other. This appends loosely |
| // related traces to be near each other. |
| merge_traces(false); |
| |
| // Re-order all the remaining traces by frequency |
| reorder_traces(size); |
| |
| assert(_cfg.number_of_blocks() >= (uint) (size - 1), "number of blocks can not shrink"); |
| } |
| |
| |
| // Edge e completes a loop in a trace. If the target block is head of the |
| // loop, rotate the loop block so that the loop ends in a conditional branch. |
| bool Trace::backedge(CFGEdge *e) { |
| bool loop_rotated = false; |
| Block *src_block = e->from(); |
| Block *targ_block = e->to(); |
| |
| assert(last_block() == src_block, "loop discovery at back branch"); |
| if (first_block() == targ_block) { |
| if (BlockLayoutRotateLoops && last_block()->num_fall_throughs() < 2) { |
| // Find the last block in the trace that has a conditional |
| // branch. |
| Block *b; |
| for (b = last_block(); b != NULL; b = prev(b)) { |
| if (b->num_fall_throughs() == 2) { |
| break; |
| } |
| } |
| |
| if (b != last_block() && b != NULL) { |
| loop_rotated = true; |
| |
| // Rotate the loop by doing two-part linked-list surgery. |
| append(first_block()); |
| break_loop_after(b); |
| } |
| } |
| |
| // Backbranch to the top of a trace |
| // Scroll forward through the trace from the targ_block. If we find |
| // a loop head before another loop top, use the the loop head alignment. |
| for (Block *b = targ_block; b != NULL; b = next(b)) { |
| if (b->has_loop_alignment()) { |
| break; |
| } |
| if (b->head()->is_Loop()) { |
| targ_block = b; |
| break; |
| } |
| } |
| |
| first_block()->set_loop_alignment(targ_block); |
| |
| } else { |
| // Backbranch into the middle of a trace |
| targ_block->set_loop_alignment(targ_block); |
| } |
| |
| return loop_rotated; |
| } |
| |
| // push blocks onto the CFG list |
| // ensure that blocks have the correct two-way branch sense |
| void Trace::fixup_blocks(PhaseCFG &cfg) { |
| Block *last = last_block(); |
| for (Block *b = first_block(); b != NULL; b = next(b)) { |
| cfg.add_block(b); |
| if (!b->is_connector()) { |
| int nfallthru = b->num_fall_throughs(); |
| if (b != last) { |
| if (nfallthru == 2) { |
| // Ensure that the sense of the branch is correct |
| Block *bnext = next(b); |
| Block *bs0 = b->non_connector_successor(0); |
| |
| MachNode *iff = b->get_node(b->number_of_nodes() - 3)->as_Mach(); |
| ProjNode *proj0 = b->get_node(b->number_of_nodes() - 2)->as_Proj(); |
| ProjNode *proj1 = b->get_node(b->number_of_nodes() - 1)->as_Proj(); |
| |
| if (bnext == bs0) { |
| // Fall-thru case in succs[0], should be in succs[1] |
| |
| // 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 projections to match targets |
| b->map_node(proj1, b->number_of_nodes() - 2); |
| b->map_node(proj0, b->number_of_nodes() - 1); |
| } |
| } |
| } |
| } |
| } |
| } |