--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/opto/block.cpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,1781 @@
+/*
+ * Copyright (c) 1997, 2016, 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 "memory/resourceArea.hpp"
+#include "compiler/compilerDirectives.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() const {
+ // 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)
+, _regalloc(NULL)
+, _scheduling_for_pressure(false)
+, _root(root)
+, _matcher(matcher)
+, _node_to_block_mapping(arena)
+, _node_latency(NULL)
+#ifndef PRODUCT
+, _trace_opto_pipelining(C->directive()->TraceOptoPipeliningOption)
+#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 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 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 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 ) {
+ // 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 {
+ // That loop may already have a loop top (we're reaching it again
+ // through the backedge of an outer loop)
+ Block* b = prev(targ_block);
+ bool has_top = targ_block->head()->is_Loop() && b->has_loop_alignment() && !b->head()->is_Loop();
+ if (!has_top) {
+ // 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);
+ }
+ }
+ }
+ }
+ }
+}