graal-jvmci-8: src/share/vm/opto/gcm.cpp comparison

comparison src/share/vm/opto/gcm.cpp @ 0:a61af66fc99e jdk7-b24

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author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
parents
children	6152cbb08ce9

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+:a61af66fc99e
+/*
+* Copyright 1997-2007 Sun Microsystems, Inc.  All Rights Reserved.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* This code is free software; you can redistribute it and/or modify it
+* under the terms of the GNU General Public License version 2 only, as
+* published by the Free Software Foundation.
+*
+* This code is distributed in the hope that it will be useful, but WITHOUT
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+* version 2 for more details (a copy is included in the LICENSE file that
+* accompanied this code).
+*
+* You should have received a copy of the GNU General Public License version
+* 2 along with this work; if not, write to the Free Software Foundation,
+* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+*
+* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+* CA 95054 USA or visit www.sun.com if you need additional information or
+* have any questions.
+*
+*/
+// Portions of code courtesy of Clifford Click
+// Optimization - Graph Style
+#include "incls/_precompiled.incl"
+#include "incls/_gcm.cpp.incl"
+//----------------------------schedule_node_into_block-------------------------
+// Insert node n into block b. Look for projections of n and make sure they
+// are in b also.
+void PhaseCFG::schedule_node_into_block( Node *n, Block *b ) {
+// Set basic block of n, Add n to b,
+_bbs.map(n->_idx, b);
+b->add_inst(n);
+// After Matching, nearly any old Node may have projections trailing it.
+// These are usually machine-dependent flags.  In any case, they might
+// float to another block below this one.  Move them up.
+for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
+Node*  use  = n->fast_out(i);
+if (use->is_Proj()) {
+Block* buse = _bbs[use->_idx];
+if (buse != b) {              // In wrong block?
+if (buse != NULL)
+buse->find_remove(use);   // Remove from wrong block
+_bbs.map(use->_idx, b);     // Re-insert in this block
+b->add_inst(use);
+}
+}
+}
+}
+//------------------------------schedule_pinned_nodes--------------------------
+// Set the basic block for Nodes pinned into blocks
+void PhaseCFG::schedule_pinned_nodes( VectorSet &visited ) {
+// Allocate node stack of size C->unique()+8 to avoid frequent realloc
+GrowableArray <Node *> spstack(C->unique()+8);
+spstack.push(_root);
+while ( spstack.is_nonempty() ) {
+Node *n = spstack.pop();
+if( !visited.test_set(n->_idx) ) { // Test node and flag it as visited
+if( n->pinned() && !_bbs.lookup(n->_idx) ) {  // Pinned?  Nail it down!
+Node *input = n->in(0);
+assert( input, "pinned Node must have Control" );
+while( !input->is_block_start() )
+input = input->in(0);
+Block *b = _bbs[input->_idx];  // Basic block of controlling input
+schedule_node_into_block(n, b);
+}
+for( int i = n->req() - 1; i >= 0; --i ) {  // For all inputs
+if( n->in(i) != NULL )
+spstack.push(n->in(i));
+}
+}
+}
+}
+#ifdef ASSERT
+// Assert that new input b2 is dominated by all previous inputs.
+// Check this by by seeing that it is dominated by b1, the deepest
+// input observed until b2.
+static void assert_dom(Block* b1, Block* b2, Node* n, Block_Array &bbs) {
+if (b1 == NULL)  return;
+assert(b1->_dom_depth < b2->_dom_depth, "sanity");
+Block* tmp = b2;
+while (tmp != b1 && tmp != NULL) {
+tmp = tmp->_idom;
+}
+if (tmp != b1) {
+// Detected an unschedulable graph.  Print some nice stuff and die.
+tty->print_cr("!!! Unschedulable graph !!!");
+for (uint j=0; j<n->len(); j++) { // For all inputs
+Node* inn = n->in(j); // Get input
+if (inn == NULL)  continue;  // Ignore NULL, missing inputs
+Block* inb = bbs[inn->_idx];
+tty->print("B%d idom=B%d depth=%2d ",inb->_pre_order,
+inb->_idom ? inb->_idom->_pre_order : 0, inb->_dom_depth);
+inn->dump();
+}
+tty->print("Failing node: ");
+n->dump();
+assert(false, "unscheduable graph");
+}
+}
+#endif
+static Block* find_deepest_input(Node* n, Block_Array &bbs) {
+// Find the last input dominated by all other inputs.
+Block* deepb           = NULL;        // Deepest block so far
+int    deepb_dom_depth = 0;
+for (uint k = 0; k < n->len(); k++) { // For all inputs
+Node* inn = n->in(k);               // Get input
+if (inn == NULL)  continue;         // Ignore NULL, missing inputs
+Block* inb = bbs[inn->_idx];
+assert(inb != NULL, "must already have scheduled this input");
+if (deepb_dom_depth < (int) inb->_dom_depth) {
+// The new inb must be dominated by the previous deepb.
+// The various inputs must be linearly ordered in the dom
+// tree, or else there will not be a unique deepest block.
+DEBUG_ONLY(assert_dom(deepb, inb, n, bbs));
+deepb = inb;                      // Save deepest block
+deepb_dom_depth = deepb->_dom_depth;
+}
+}
+assert(deepb != NULL, "must be at least one input to n");
+return deepb;
+}
+//------------------------------schedule_early---------------------------------
+// Find the earliest Block any instruction can be placed in.  Some instructions
+// are pinned into Blocks.  Unpinned instructions can appear in last block in
+// which all their inputs occur.
+bool PhaseCFG::schedule_early(VectorSet &visited, Node_List &roots) {
+// Allocate stack with enough space to avoid frequent realloc
+Node_Stack nstack(roots.Size() + 8); // (unique >> 1) + 24 from Java2D stats
+// roots.push(_root); _root will be processed among C->top() inputs
+roots.push(C->top());
+visited.set(C->top()->_idx);
+while (roots.size() != 0) {
+// Use local variables nstack_top_n & nstack_top_i to cache values
+// on stack's top.
+Node *nstack_top_n = roots.pop();
+uint  nstack_top_i = 0;
+//while_nstack_nonempty:
+while (true) {
+// Get parent node and next input's index from stack's top.
+Node *n = nstack_top_n;
+uint  i = nstack_top_i;
+if (i == 0) {
+// Special control input processing.
+// While I am here, go ahead and look for Nodes which are taking control
+// from a is_block_proj Node.  After I inserted RegionNodes to make proper
+// blocks, the control at a is_block_proj more properly comes from the
+// Region being controlled by the block_proj Node.
+const Node *in0 = n->in(0);
+if (in0 != NULL) {              // Control-dependent?
+const Node *p = in0->is_block_proj();
+if (p != NULL && p != n) {    // Control from a block projection?
+// Find trailing Region
+Block *pb = _bbs[in0->_idx]; // Block-projection already has basic block
+uint j = 0;
+if (pb->_num_succs != 1) {  // More then 1 successor?
+// Search for successor
+uint max = pb->_nodes.size();
+assert( max > 1, "" );
+uint start = max - pb->_num_succs;
+// Find which output path belongs to projection
+for (j = start; j < max; j++) {
+if( pb->_nodes[j] == in0 )
+break;
+}
+assert( j < max, "must find" );
+// Change control to match head of successor basic block
+j -= start;
+}
+n->set_req(0, pb->_succs[j]->head());
+}
+} else {               // n->in(0) == NULL
+if (n->req() == 1) { // This guy is a constant with NO inputs?
+n->set_req(0, _root);
+}
+}
+}
+// First, visit all inputs and force them to get a block.  If an
+// input is already in a block we quit following inputs (to avoid
+// cycles). Instead we put that Node on a worklist to be handled
+// later (since IT'S inputs may not have a block yet).
+bool done = true;              // Assume all n's inputs will be processed
+while (i < n->len()) {         // For all inputs
+Node *in = n->in(i);         // Get input
+++i;
+if (in == NULL) continue;    // Ignore NULL, missing inputs
+int is_visited = visited.test_set(in->_idx);
+if (!_bbs.lookup(in->_idx)) { // Missing block selection?
+if (is_visited) {
+// assert( !visited.test(in->_idx), "did not schedule early" );
+return false;
+}
+nstack.push(n, i);         // Save parent node and next input's index.
+nstack_top_n = in;         // Process current input now.
+nstack_top_i = 0;
+done = false;              // Not all n's inputs processed.
+break; // continue while_nstack_nonempty;
+} else if (!is_visited) {    // Input not yet visited?
+roots.push(in);            // Visit this guy later, using worklist
+}
+}
+if (done) {
+// All of n's inputs have been processed, complete post-processing.
+// Some instructions are pinned into a block.  These include Region,
+// Phi, Start, Return, and other control-dependent instructions and
+// any projections which depend on them.
+if (!n->pinned()) {
+// Set earliest legal block.
+_bbs.map(n->_idx, find_deepest_input(n, _bbs));
+}
+if (nstack.is_empty()) {
+// Finished all nodes on stack.
+// Process next node on the worklist 'roots'.
+break;
+}
+// Get saved parent node and next input's index.
+nstack_top_n = nstack.node();
+nstack_top_i = nstack.index();
+nstack.pop();
+} //    if (done)
+}   // while (true)
+}     // while (roots.size() != 0)
+return true;
+}
+//------------------------------dom_lca----------------------------------------
+// Find least common ancestor in dominator tree
+// LCA is a current notion of LCA, to be raised above 'this'.
+// As a convenient boundary condition, return 'this' if LCA is NULL.
+// Find the LCA of those two nodes.
+Block* Block::dom_lca(Block* LCA) {
+if (LCA == NULL || LCA == this)  return this;
+Block* anc = this;
+while (anc->_dom_depth > LCA->_dom_depth)
+anc = anc->_idom;           // Walk up till anc is as high as LCA
+while (LCA->_dom_depth > anc->_dom_depth)
+LCA = LCA->_idom;           // Walk up till LCA is as high as anc
+while (LCA != anc) {          // Walk both up till they are the same
+LCA = LCA->_idom;
+anc = anc->_idom;
+}
+return LCA;
+}
+//--------------------------raise_LCA_above_use--------------------------------
+// We are placing a definition, and have been given a def->use edge.
+// The definition must dominate the use, so move the LCA upward in the
+// dominator tree to dominate the use.  If the use is a phi, adjust
+// the LCA only with the phi input paths which actually use this def.
+static Block* raise_LCA_above_use(Block* LCA, Node* use, Node* def, Block_Array &bbs) {
+Block* buse = bbs[use->_idx];
+if (buse == NULL)    return LCA;   // Unused killing Projs have no use block
+if (!use->is_Phi())  return buse->dom_lca(LCA);
+uint pmax = use->req();       // Number of Phi inputs
+// Why does not this loop just break after finding the matching input to
+// the Phi?  Well...it's like this.  I do not have true def-use/use-def
+// chains.  Means I cannot distinguish, from the def-use direction, which
+// of many use-defs lead from the same use to the same def.  That is, this
+// Phi might have several uses of the same def.  Each use appears in a
+// different predecessor block.  But when I enter here, I cannot distinguish
+// which use-def edge I should find the predecessor block for.  So I find
+// them all.  Means I do a little extra work if a Phi uses the same value
+// more than once.
+for (uint j=1; j<pmax; j++) { // For all inputs
+if (use->in(j) == def) {    // Found matching input?
+Block* pred = bbs[buse->pred(j)->_idx];
+LCA = pred->dom_lca(LCA);
+}
+}
+return LCA;
+}
+//----------------------------raise_LCA_above_marks----------------------------
+// Return a new LCA that dominates LCA and any of its marked predecessors.
+// Search all my parents up to 'early' (exclusive), looking for predecessors
+// which are marked with the given index.  Return the LCA (in the dom tree)
+// of all marked blocks.  If there are none marked, return the original
+// LCA.
+static Block* raise_LCA_above_marks(Block* LCA, node_idx_t mark,
+Block* early, Block_Array &bbs) {
+Block_List worklist;
+worklist.push(LCA);
+while (worklist.size() > 0) {
+Block* mid = worklist.pop();
+if (mid == early)  continue;  // stop searching here
+// Test and set the visited bit.
+if (mid->raise_LCA_visited() == mark)  continue;  // already visited
+mid->set_raise_LCA_visited(mark);
+// Don't process the current LCA, otherwise the search may terminate early
+if (mid != LCA && mid->raise_LCA_mark() == mark) {
+// Raise the LCA.
+LCA = mid->dom_lca(LCA);
+if (LCA == early)  break;   // stop searching everywhere
+assert(early->dominates(LCA), "early is high enough");
+// Resume searching at that point, skipping intermediate levels.
+worklist.push(LCA);
+} else {
+// Keep searching through this block's predecessors.
+for (uint j = 1, jmax = mid->num_preds(); j < jmax; j++) {
+Block* mid_parent = bbs[ mid->pred(j)->_idx ];
+worklist.push(mid_parent);
+}
+}
+}
+return LCA;
+}
+//--------------------------memory_early_block--------------------------------
+// This is a variation of find_deepest_input, the heart of schedule_early.
+// Find the "early" block for a load, if we considered only memory and
+// address inputs, that is, if other data inputs were ignored.
+//
+// Because a subset of edges are considered, the resulting block will
+// be earlier (at a shallower dom_depth) than the true schedule_early
+// point of the node. We compute this earlier block as a more permissive
+// site for anti-dependency insertion, but only if subsume_loads is enabled.
+static Block* memory_early_block(Node* load, Block* early, Block_Array &bbs) {
+Node* base;
+Node* index;
+Node* store = load->in(MemNode::Memory);
+load->as_Mach()->memory_inputs(base, index);
+assert(base != NodeSentinel && index != NodeSentinel,
+"unexpected base/index inputs");
+Node* mem_inputs[4];
+int mem_inputs_length = 0;
+if (base != NULL)  mem_inputs[mem_inputs_length++] = base;
+if (index != NULL) mem_inputs[mem_inputs_length++] = index;
+if (store != NULL) mem_inputs[mem_inputs_length++] = store;
+// In the comparision below, add one to account for the control input,
+// which may be null, but always takes up a spot in the in array.
+if (mem_inputs_length + 1 < (int) load->req()) {
+// This "load" has more inputs than just the memory, base and index inputs.
+// For purposes of checking anti-dependences, we need to start
+// from the early block of only the address portion of the instruction,
+// and ignore other blocks that may have factored into the wider
+// schedule_early calculation.
+if (load->in(0) != NULL) mem_inputs[mem_inputs_length++] = load->in(0);
+Block* deepb           = NULL;        // Deepest block so far
+int    deepb_dom_depth = 0;
+for (int i = 0; i < mem_inputs_length; i++) {
+Block* inb = bbs[mem_inputs[i]->_idx];
+if (deepb_dom_depth < (int) inb->_dom_depth) {
+// The new inb must be dominated by the previous deepb.
+// The various inputs must be linearly ordered in the dom
+// tree, or else there will not be a unique deepest block.
+DEBUG_ONLY(assert_dom(deepb, inb, load, bbs));
+deepb = inb;                      // Save deepest block
+deepb_dom_depth = deepb->_dom_depth;
+}
+}
+early = deepb;
+}
+return early;
+}
+//--------------------------insert_anti_dependences---------------------------
+// A load may need to witness memory that nearby stores can overwrite.
+// For each nearby store, either insert an "anti-dependence" edge
+// from the load to the store, or else move LCA upward to force the
+// load to (eventually) be scheduled in a block above the store.
+//
+// Do not add edges to stores on distinct control-flow paths;
+// only add edges to stores which might interfere.
+//
+// Return the (updated) LCA.  There will not be any possibly interfering
+// store between the load's "early block" and the updated LCA.
+// Any stores in the updated LCA will have new precedence edges
+// back to the load.  The caller is expected to schedule the load
+// in the LCA, in which case the precedence edges will make LCM
+// preserve anti-dependences.  The caller may also hoist the load
+// above the LCA, if it is not the early block.
+Block* PhaseCFG::insert_anti_dependences(Block* LCA, Node* load, bool verify) {
+assert(load->needs_anti_dependence_check(), "must be a load of some sort");
+assert(LCA != NULL, "");
+DEBUG_ONLY(Block* LCA_orig = LCA);
+// Compute the alias index.  Loads and stores with different alias indices
+// do not need anti-dependence edges.
+uint load_alias_idx = C->get_alias_index(load->adr_type());
+#ifdef ASSERT
+if (load_alias_idx == Compile::AliasIdxBot && C->AliasLevel() > 0 &&
+(PrintOpto || VerifyAliases ||
+PrintMiscellaneous && (WizardMode || Verbose))) {
+// Load nodes should not consume all of memory.
+// Reporting a bottom type indicates a bug in adlc.
+// If some particular type of node validly consumes all of memory,
+// sharpen the preceding "if" to exclude it, so we can catch bugs here.
+tty->print_cr("*** Possible Anti-Dependence Bug:  Load consumes all of memory.");
+load->dump(2);
+if (VerifyAliases)  assert(load_alias_idx != Compile::AliasIdxBot, "");
+}
+#endif
+assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrComp),
+"String compare is only known 'load' that does not conflict with any stores");
+if (!C->alias_type(load_alias_idx)->is_rewritable()) {
+// It is impossible to spoil this load by putting stores before it,
+// because we know that the stores will never update the value
+// which 'load' must witness.
+return LCA;
+}
+node_idx_t load_index = load->_idx;
+// Note the earliest legal placement of 'load', as determined by
+// by the unique point in the dom tree where all memory effects
+// and other inputs are first available.  (Computed by schedule_early.)
+// For normal loads, 'early' is the shallowest place (dom graph wise)
+// to look for anti-deps between this load and any store.
+Block* early = _bbs[load_index];
+// If we are subsuming loads, compute an "early" block that only considers
+// memory or address inputs. This block may be different than the
+// schedule_early block in that it could be at an even shallower depth in the
+// dominator tree, and allow for a broader discovery of anti-dependences.
+if (C->subsume_loads()) {
+early = memory_early_block(load, early, _bbs);
+}
+ResourceArea *area = Thread::current()->resource_area();
+Node_List worklist_mem(area);     // prior memory state to store
+Node_List worklist_store(area);   // possible-def to explore
+Node_List non_early_stores(area); // all relevant stores outside of early
+bool must_raise_LCA = false;
+DEBUG_ONLY(VectorSet should_not_repeat(area));
+#ifdef TRACK_PHI_INPUTS
+// %%% This extra checking fails because MergeMem nodes are not GVNed.
+// Provide "phi_inputs" to check if every input to a PhiNode is from the
+// original memory state.  This indicates a PhiNode for which should not
+// prevent the load from sinking.  For such a block, set_raise_LCA_mark
+// may be overly conservative.
+// Mechanism: count inputs seen for each Phi encountered in worklist_store.
+DEBUG_ONLY(GrowableArray<uint> phi_inputs(area, C->unique(),0,0));
+#endif
+// 'load' uses some memory state; look for users of the same state.
+// Recurse through MergeMem nodes to the stores that use them.
+// Each of these stores is a possible definition of memory
+// that 'load' needs to use.  We need to force 'load'
+// to occur before each such store.  When the store is in
+// the same block as 'load', we insert an anti-dependence
+// edge load->store.
+// The relevant stores "nearby" the load consist of a tree rooted
+// at initial_mem, with internal nodes of type MergeMem.
+// Therefore, the branches visited by the worklist are of this form:
+//    initial_mem -> (MergeMem ->)* store
+// The anti-dependence constraints apply only to the fringe of this tree.
+Node* initial_mem = load->in(MemNode::Memory);
+worklist_store.push(initial_mem);
+worklist_mem.push(NULL);
+DEBUG_ONLY(should_not_repeat.test_set(initial_mem->_idx));
+while (worklist_store.size() > 0) {
+// Examine a nearby store to see if it might interfere with our load.
+Node* mem   = worklist_mem.pop();
+Node* store = worklist_store.pop();
+uint op = store->Opcode();
+// MergeMems do not directly have anti-deps.
+// Treat them as internal nodes in a forward tree of memory states,
+// the leaves of which are each a 'possible-def'.
+if (store == initial_mem    // root (exclusive) of tree we are searching
+|| op == Op_MergeMem    // internal node of tree we are searching
+) {
+mem = store;   // It's not a possibly interfering store.
+for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
+store = mem->fast_out(i);
+if (store->is_MergeMem()) {
+// Be sure we don't get into combinatorial problems.
+// (Allow phis to be repeated; they can merge two relevant states.)
+uint i = worklist_store.size();
+for (; i > 0; i--) {
+if (worklist_store.at(i-1) == store)  break;
+}
+if (i > 0)  continue; // already on work list; do not repeat
+DEBUG_ONLY(int repeated = should_not_repeat.test_set(store->_idx));
+assert(!repeated, "do not walk merges twice");
+}
+worklist_mem.push(mem);
+worklist_store.push(store);
+}
+continue;
+}
+if (op == Op_MachProj || op == Op_Catch)   continue;
+if (store->needs_anti_dependence_check())  continue;  // not really a store
+// Compute the alias index.  Loads and stores with different alias
+// indices do not need anti-dependence edges.  Wide MemBar's are
+// anti-dependent on everything (except immutable memories).
+const TypePtr* adr_type = store->adr_type();
+if (!C->can_alias(adr_type, load_alias_idx))  continue;
+// Most slow-path runtime calls do NOT modify Java memory, but
+// they can block and so write Raw memory.
+if (store->is_Mach()) {
+MachNode* mstore = store->as_Mach();
+if (load_alias_idx != Compile::AliasIdxRaw) {
+// Check for call into the runtime using the Java calling
+// convention (and from there into a wrapper); it has no
+// _method.  Can't do this optimization for Native calls because
+// they CAN write to Java memory.
+if (mstore->ideal_Opcode() == Op_CallStaticJava) {
+assert(mstore->is_MachSafePoint(), "");
+MachSafePointNode* ms = (MachSafePointNode*) mstore;
+assert(ms->is_MachCallJava(), "");
+MachCallJavaNode* mcj = (MachCallJavaNode*) ms;
+if (mcj->_method == NULL) {
+// These runtime calls do not write to Java visible memory
+// (other than Raw) and so do not require anti-dependence edges.
+continue;
+}
+}
+// Same for SafePoints: they read/write Raw but only read otherwise.
+// This is basically a workaround for SafePoints only defining control
+// instead of control + memory.
+if (mstore->ideal_Opcode() == Op_SafePoint)
+continue;
+} else {
+// Some raw memory, such as the load of "top" at an allocation,
+// can be control dependent on the previous safepoint. See
+// comments in GraphKit::allocate_heap() about control input.
+// Inserting an anti-dep between such a safepoint and a use
+// creates a cycle, and will cause a subsequent failure in
+// local scheduling.  (BugId 4919904)
+// (%%% How can a control input be a safepoint and not a projection??)
+if (mstore->ideal_Opcode() == Op_SafePoint && load->in(0) == mstore)
+continue;
+}
+}
+// Identify a block that the current load must be above,
+// or else observe that 'store' is all the way up in the
+// earliest legal block for 'load'.  In the latter case,
+// immediately insert an anti-dependence edge.
+Block* store_block = _bbs[store->_idx];
+assert(store_block != NULL, "unused killing projections skipped above");
+if (store->is_Phi()) {
+// 'load' uses memory which is one (or more) of the Phi's inputs.
+// It must be scheduled not before the Phi, but rather before
+// each of the relevant Phi inputs.
+//
+// Instead of finding the LCA of all inputs to a Phi that match 'mem',
+// we mark each corresponding predecessor block and do a combined
+// hoisting operation later (raise_LCA_above_marks).
+//
+// Do not assert(store_block != early, "Phi merging memory after access")
+// PhiNode may be at start of block 'early' with backedge to 'early'
+DEBUG_ONLY(bool found_match = false);
+for (uint j = PhiNode::Input, jmax = store->req(); j < jmax; j++) {
+if (store->in(j) == mem) {   // Found matching input?
+DEBUG_ONLY(found_match = true);
+Block* pred_block = _bbs[store_block->pred(j)->_idx];
+if (pred_block != early) {
+// If any predecessor of the Phi matches the load's "early block",
+// we do not need a precedence edge between the Phi and 'load'
+// since the load will be forced into a block preceeding the Phi.
+pred_block->set_raise_LCA_mark(load_index);
+assert(!LCA_orig->dominates(pred_block) ||
+early->dominates(pred_block), "early is high enough");
+must_raise_LCA = true;
+}
+}
+}
+assert(found_match, "no worklist bug");
+#ifdef TRACK_PHI_INPUTS
+#ifdef ASSERT
+// This assert asks about correct handling of PhiNodes, which may not
+// have all input edges directly from 'mem'. See BugId 4621264
+int num_mem_inputs = phi_inputs.at_grow(store->_idx,0) + 1;
+// Increment by exactly one even if there are multiple copies of 'mem'
+// coming into the phi, because we will run this block several times
+// if there are several copies of 'mem'.  (That's how DU iterators work.)
+phi_inputs.at_put(store->_idx, num_mem_inputs);
+assert(PhiNode::Input + num_mem_inputs < store->req(),
+"Expect at least one phi input will not be from original memory state");
+#endif //ASSERT
+#endif //TRACK_PHI_INPUTS
+} else if (store_block != early) {
+// 'store' is between the current LCA and earliest possible block.
+// Label its block, and decide later on how to raise the LCA
+// to include the effect on LCA of this store.
+// If this store's block gets chosen as the raised LCA, we
+// will find him on the non_early_stores list and stick him
+// with a precedence edge.
+// (But, don't bother if LCA is already raised all the way.)
+if (LCA != early) {
+store_block->set_raise_LCA_mark(load_index);
+must_raise_LCA = true;
+non_early_stores.push(store);
+}
+} else {
+// Found a possibly-interfering store in the load's 'early' block.
+// This means 'load' cannot sink at all in the dominator tree.
+// Add an anti-dep edge, and squeeze 'load' into the highest block.
+assert(store != load->in(0), "dependence cycle found");
+if (verify) {
+assert(store->find_edge(load) != -1, "missing precedence edge");
+} else {
+store->add_prec(load);
+}
+LCA = early;
+// This turns off the process of gathering non_early_stores.
+}
+}
+// (Worklist is now empty; all nearby stores have been visited.)
+// Finished if 'load' must be scheduled in its 'early' block.
+// If we found any stores there, they have already been given
+// precedence edges.
+if (LCA == early)  return LCA;
+// We get here only if there are no possibly-interfering stores
+// in the load's 'early' block.  Move LCA up above all predecessors
+// which contain stores we have noted.
+//
+// The raised LCA block can be a home to such interfering stores,
+// but its predecessors must not contain any such stores.
+//
+// The raised LCA will be a lower bound for placing the load,
+// preventing the load from sinking past any block containing
+// a store that may invalidate the memory state required by 'load'.
+if (must_raise_LCA)
+LCA = raise_LCA_above_marks(LCA, load->_idx, early, _bbs);
+if (LCA == early)  return LCA;
+// Insert anti-dependence edges from 'load' to each store
+// in the non-early LCA block.
+// Mine the non_early_stores list for such stores.
+if (LCA->raise_LCA_mark() == load_index) {
+while (non_early_stores.size() > 0) {
+Node* store = non_early_stores.pop();
+Block* store_block = _bbs[store->_idx];
+if (store_block == LCA) {
+// add anti_dependence from store to load in its own block
+assert(store != load->in(0), "dependence cycle found");
+if (verify) {
+assert(store->find_edge(load) != -1, "missing precedence edge");
+} else {
+store->add_prec(load);
+}
+} else {
+assert(store_block->raise_LCA_mark() == load_index, "block was marked");
+// Any other stores we found must be either inside the new LCA
+// or else outside the original LCA.  In the latter case, they
+// did not interfere with any use of 'load'.
+assert(LCA->dominates(store_block)
+|| !LCA_orig->dominates(store_block), "no stray stores");
+}
+}
+}
+// Return the highest block containing stores; any stores
+// within that block have been given anti-dependence edges.
+return LCA;
+}
+// This class is used to iterate backwards over the nodes in the graph.
+class Node_Backward_Iterator {
+private:
+Node_Backward_Iterator();
+public:
+// Constructor for the iterator
+Node_Backward_Iterator(Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs);
+// Postincrement operator to iterate over the nodes
+Node *next();
+private:
+VectorSet   &_visited;
+Node_List   &_stack;
+Block_Array &_bbs;
+};
+// Constructor for the Node_Backward_Iterator
+Node_Backward_Iterator::Node_Backward_Iterator( Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs )
+: _visited(visited), _stack(stack), _bbs(bbs) {
+// The stack should contain exactly the root
+stack.clear();
+stack.push(root);
+// Clear the visited bits
+visited.Clear();
+}
+// Iterator for the Node_Backward_Iterator
+Node *Node_Backward_Iterator::next() {
+// If the _stack is empty, then just return NULL: finished.
+if ( !_stack.size() )
+return NULL;
+// '_stack' is emulating a real _stack.  The 'visit-all-users' loop has been
+// made stateless, so I do not need to record the index 'i' on my _stack.
+// Instead I visit all users each time, scanning for unvisited users.
+// I visit unvisited not-anti-dependence users first, then anti-dependent
+// children next.
+Node *self = _stack.pop();
+// I cycle here when I am entering a deeper level of recursion.
+// The key variable 'self' was set prior to jumping here.
+while( 1 ) {
+_visited.set(self->_idx);
+// Now schedule all uses as late as possible.
+uint src     = self->is_Proj() ? self->in(0)->_idx : self->_idx;
+uint src_rpo = _bbs[src]->_rpo;
+// Schedule all nodes in a post-order visit
+Node *unvisited = NULL;  // Unvisited anti-dependent Node, if any
+// Scan for unvisited nodes
+for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) {
+// For all uses, schedule late
+Node* n = self->fast_out(i); // Use
+// Skip already visited children
+if ( _visited.test(n->_idx) )
+continue;
+// do not traverse backward control edges
+Node *use = n->is_Proj() ? n->in(0) : n;
+uint use_rpo = _bbs[use->_idx]->_rpo;
+if ( use_rpo < src_rpo )
+continue;
+// Phi nodes always precede uses in a basic block
+if ( use_rpo == src_rpo && use->is_Phi() )
+continue;
+unvisited = n;      // Found unvisited
+// Check for possible-anti-dependent
+if( !n->needs_anti_dependence_check() )
+break;            // Not visited, not anti-dep; schedule it NOW
+}
+// Did I find an unvisited not-anti-dependent Node?
+if ( !unvisited )
+break;                  // All done with children; post-visit 'self'
+// Visit the unvisited Node.  Contains the obvious push to
+// indicate I'm entering a deeper level of recursion.  I push the
+// old state onto the _stack and set a new state and loop (recurse).
+_stack.push(self);
+self = unvisited;
+} // End recursion loop
+return self;
+}
+//------------------------------ComputeLatenciesBackwards----------------------
+// Compute the latency of all the instructions.
+void PhaseCFG::ComputeLatenciesBackwards(VectorSet &visited, Node_List &stack) {
+#ifndef PRODUCT
+if (trace_opto_pipelining())
+tty->print("\n#---- ComputeLatenciesBackwards ----\n");
+#endif
+Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs);
+Node *n;
+// Walk over all the nodes from last to first
+while (n = iter.next()) {
+// Set the latency for the definitions of this instruction
+partial_latency_of_defs(n);
+}
+} // end ComputeLatenciesBackwards
+//------------------------------partial_latency_of_defs------------------------
+// Compute the latency impact of this node on all defs.  This computes
+// a number that increases as we approach the beginning of the routine.
+void PhaseCFG::partial_latency_of_defs(Node *n) {
+// Set the latency for this instruction
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print("# latency_to_inputs: node_latency[%d] = %d for node",
+n->_idx, _node_latency.at_grow(n->_idx));
+dump();
+}
+#endif
+if (n->is_Proj())
+n = n->in(0);
+if (n->is_Root())
+return;
+uint nlen = n->len();
+uint use_latency = _node_latency.at_grow(n->_idx);
+uint use_pre_order = _bbs[n->_idx]->_pre_order;
+for ( uint j=0; j<nlen; j++ ) {
+Node *def = n->in(j);
+if (!def || def == n)
+continue;
+// Walk backwards thru projections
+if (def->is_Proj())
+def = def->in(0);
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print("#    in(%2d): ", j);
+def->dump();
+}
+#endif
+// If the defining block is not known, assume it is ok
+Block *def_block = _bbs[def->_idx];
+uint def_pre_order = def_block ? def_block->_pre_order : 0;
+if ( (use_pre_order <  def_pre_order) ||
+(use_pre_order == def_pre_order && n->is_Phi()) )
+continue;
+uint delta_latency = n->latency(j);
+uint current_latency = delta_latency + use_latency;
+if (_node_latency.at_grow(def->_idx) < current_latency) {
+_node_latency.at_put_grow(def->_idx, current_latency);
+}
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print_cr("#      %d + edge_latency(%d) == %d -> %d, node_latency[%d] = %d",
+use_latency, j, delta_latency, current_latency, def->_idx,
+_node_latency.at_grow(def->_idx));
+}
+#endif
+}
+}
+//------------------------------latency_from_use-------------------------------
+// Compute the latency of a specific use
+int PhaseCFG::latency_from_use(Node *n, const Node *def, Node *use) {
+// If self-reference, return no latency
+if (use == n || use->is_Root())
+return 0;
+uint def_pre_order = _bbs[def->_idx]->_pre_order;
+uint latency = 0;
+// If the use is not a projection, then it is simple...
+if (!use->is_Proj()) {
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print("#    out(): ");
+use->dump();
+}
+#endif
+uint use_pre_order = _bbs[use->_idx]->_pre_order;
+if (use_pre_order < def_pre_order)
+return 0;
+if (use_pre_order == def_pre_order && use->is_Phi())
+return 0;
+uint nlen = use->len();
+uint nl = _node_latency.at_grow(use->_idx);
+for ( uint j=0; j<nlen; j++ ) {
+if (use->in(j) == n) {
+// Change this if we want local latencies
+uint ul = use->latency(j);
+uint  l = ul + nl;
+if (latency < l) latency = l;
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print_cr("#      %d + edge_latency(%d) == %d -> %d, latency = %d",
+nl, j, ul, l, latency);
+}
+#endif
+}
+}
+} else {
+// This is a projection, just grab the latency of the use(s)
+for (DUIterator_Fast jmax, j = use->fast_outs(jmax); j < jmax; j++) {
+uint l = latency_from_use(use, def, use->fast_out(j));
+if (latency < l) latency = l;
+}
+}
+return latency;
+}
+//------------------------------latency_from_uses------------------------------
+// Compute the latency of this instruction relative to all of it's uses.
+// This computes a number that increases as we approach the beginning of the
+// routine.
+void PhaseCFG::latency_from_uses(Node *n) {
+// Set the latency for this instruction
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print("# latency_from_outputs: node_latency[%d] = %d for node",
+n->_idx, _node_latency.at_grow(n->_idx));
+dump();
+}
+#endif
+uint latency=0;
+const Node *def = n->is_Proj() ? n->in(0): n;
+for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
+uint l = latency_from_use(n, def, n->fast_out(i));
+if (latency < l) latency = l;
+}
+_node_latency.at_put_grow(n->_idx, latency);
+}
+//------------------------------hoist_to_cheaper_block-------------------------
+// Pick a block for node self, between early and LCA, that is a cheaper
+// alternative to LCA.
+Block* PhaseCFG::hoist_to_cheaper_block(Block* LCA, Block* early, Node* self) {
+const double delta = 1+PROB_UNLIKELY_MAG(4);
+Block* least       = LCA;
+double least_freq  = least->_freq;
+uint target        = _node_latency.at_grow(self->_idx);
+uint start_latency = _node_latency.at_grow(LCA->_nodes[0]->_idx);
+uint end_latency   = _node_latency.at_grow(LCA->_nodes[LCA->end_idx()]->_idx);
+bool in_latency    = (target <= start_latency);
+const Block* root_block = _bbs[_root->_idx];
+// Turn off latency scheduling if scheduling is just plain off
+if (!C->do_scheduling())
+in_latency = true;
+// Do not hoist (to cover latency) instructions which target a
+// single register.  Hoisting stretches the live range of the
+// single register and may force spilling.
+MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL;
+if (mach && mach->out_RegMask().is_bound1() && mach->out_RegMask().is_NotEmpty())
+in_latency = true;
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print("# Find cheaper block for latency %d: ",
+_node_latency.at_grow(self->_idx));
+self->dump();
+tty->print_cr("#   B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g",
+LCA->_pre_order,
+LCA->_nodes[0]->_idx,
+start_latency,
+LCA->_nodes[LCA->end_idx()]->_idx,
+end_latency,
+least_freq);
+}
+#endif
+// Walk up the dominator tree from LCA (Lowest common ancestor) to
+// the earliest legal location.  Capture the least execution frequency.
+while (LCA != early) {
+LCA = LCA->_idom;         // Follow up the dominator tree
+if (LCA == NULL) {
+// Bailout without retry
+C->record_method_not_compilable("late schedule failed: LCA == NULL");
+return least;
+}
+// Don't hoist machine instructions to the root basic block
+if (mach && LCA == root_block)
+break;
+uint start_lat = _node_latency.at_grow(LCA->_nodes[0]->_idx);
+uint end_idx   = LCA->end_idx();
+uint end_lat   = _node_latency.at_grow(LCA->_nodes[end_idx]->_idx);
+double LCA_freq = LCA->_freq;
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print_cr("#   B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g",
+LCA->_pre_order, LCA->_nodes[0]->_idx, start_lat, end_idx, end_lat, LCA_freq);
+}
+#endif
+if (LCA_freq < least_freq              || // Better Frequency
+( !in_latency                   &&    // No block containing latency
+LCA_freq < least_freq * delta &&    // No worse frequency
+target >= end_lat             &&    // within latency range
+!self->is_iteratively_computed() )  // But don't hoist IV increments
+// because they may end up above other uses of their phi forcing
+// their result register to be different from their input.
+) {
+least = LCA;            // Found cheaper block
+least_freq = LCA_freq;
+start_latency = start_lat;
+end_latency = end_lat;
+if (target <= start_lat)
+in_latency = true;
+}
+}
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print_cr("#  Choose block B%d with start latency=%d and freq=%g",
+least->_pre_order, start_latency, least_freq);
+}
+#endif
+// See if the latency needs to be updated
+if (target < end_latency) {
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print_cr("#  Change latency for [%4d] from %d to %d", self->_idx, target, end_latency);
+}
+#endif
+_node_latency.at_put_grow(self->_idx, end_latency);
+partial_latency_of_defs(self);
+}
+return least;
+}
+//------------------------------schedule_late-----------------------------------
+// Now schedule all codes as LATE as possible.  This is the LCA in the
+// dominator tree of all USES of a value.  Pick the block with the least
+// loop nesting depth that is lowest in the dominator tree.
+extern const char must_clone[];
+void PhaseCFG::schedule_late(VectorSet &visited, Node_List &stack) {
+#ifndef PRODUCT
+if (trace_opto_pipelining())
+tty->print("\n#---- schedule_late ----\n");
+#endif
+Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs);
+Node *self;
+// Walk over all the nodes from last to first
+while (self = iter.next()) {
+Block* early = _bbs[self->_idx];   // Earliest legal placement
+if (self->is_top()) {
+// Top node goes in bb #2 with other constants.
+// It must be special-cased, because it has no out edges.
+early->add_inst(self);
+continue;
+}
+// No uses, just terminate
+if (self->outcnt() == 0) {
+assert(self->Opcode() == Op_MachProj, "sanity");
+continue;                   // Must be a dead machine projection
+}
+// If node is pinned in the block, then no scheduling can be done.
+if( self->pinned() )          // Pinned in block?
+continue;
+MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL;
+if (mach) {
+switch (mach->ideal_Opcode()) {
+case Op_CreateEx:
+// Don't move exception creation
+early->add_inst(self);
+continue;
+break;
+case Op_CheckCastPP:
+// Don't move CheckCastPP nodes away from their input, if the input
+// is a rawptr (5071820).
+Node *def = self->in(1);
+if (def != NULL && def->bottom_type()->base() == Type::RawPtr) {
+early->add_inst(self);
+continue;
+}
+break;
+}
+}
+// Gather LCA of all uses
+Block *LCA = NULL;
+{
+for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) {
+// For all uses, find LCA
+Node* use = self->fast_out(i);
+LCA = raise_LCA_above_use(LCA, use, self, _bbs);
+}
+}  // (Hide defs of imax, i from rest of block.)
+// Place temps in the block of their use.  This isn't a
+// requirement for correctness but it reduces useless
+// interference between temps and other nodes.
+if (mach != NULL && mach->is_MachTemp()) {
+_bbs.map(self->_idx, LCA);
+LCA->add_inst(self);
+continue;
+}
+// Check if 'self' could be anti-dependent on memory
+if (self->needs_anti_dependence_check()) {
+// Hoist LCA above possible-defs and insert anti-dependences to
+// defs in new LCA block.
+LCA = insert_anti_dependences(LCA, self);
+}
+if (early->_dom_depth > LCA->_dom_depth) {
+// Somehow the LCA has moved above the earliest legal point.
+// (One way this can happen is via memory_early_block.)
+if (C->subsume_loads() == true && !C->failing()) {
+// Retry with subsume_loads == false
+// If this is the first failure, the sentinel string will "stick"
+// to the Compile object, and the C2Compiler will see it and retry.
+C->record_failure(C2Compiler::retry_no_subsuming_loads());
+} else {
+// Bailout without retry when (early->_dom_depth > LCA->_dom_depth)
+C->record_method_not_compilable("late schedule failed: incorrect graph");
+}
+return;
+}
+// If there is no opportunity to hoist, then we're done.
+bool try_to_hoist = (LCA != early);
+// Must clone guys stay next to use; no hoisting allowed.
+// Also cannot hoist guys that alter memory or are otherwise not
+// allocatable (hoisting can make a value live longer, leading to
+// anti and output dependency problems which are normally resolved
+// by the register allocator giving everyone a different register).
+if (mach != NULL && must_clone[mach->ideal_Opcode()])
+try_to_hoist = false;
+Block* late = NULL;
+if (try_to_hoist) {
+// Now find the block with the least execution frequency.
+// Start at the latest schedule and work up to the earliest schedule
+// in the dominator tree.  Thus the Node will dominate all its uses.
+late = hoist_to_cheaper_block(LCA, early, self);
+} else {
+// Just use the LCA of the uses.
+late = LCA;
+}
+// Put the node into target block
+schedule_node_into_block(self, late);
+#ifdef ASSERT
+if (self->needs_anti_dependence_check()) {
+// since precedence edges are only inserted when we're sure they
+// are needed make sure that after placement in a block we don't
+// need any new precedence edges.
+verify_anti_dependences(late, self);
+}
+#endif
+} // Loop until all nodes have been visited
+} // end ScheduleLate
+//------------------------------GlobalCodeMotion-------------------------------
+void PhaseCFG::GlobalCodeMotion( Matcher &matcher, uint unique, Node_List &proj_list ) {
+ResourceMark rm;
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print("\n---- Start GlobalCodeMotion ----\n");
+}
+#endif
+// Initialize the bbs.map for things on the proj_list
+uint i;
+for( i=0; i < proj_list.size(); i++ )
+_bbs.map(proj_list[i]->_idx, NULL);
+// Set the basic block for Nodes pinned into blocks
+Arena *a = Thread::current()->resource_area();
+VectorSet visited(a);
+schedule_pinned_nodes( visited );
+// Find the earliest Block any instruction can be placed in.  Some
+// instructions are pinned into Blocks.  Unpinned instructions can
+// appear in last block in which all their inputs occur.
+visited.Clear();
+Node_List stack(a);
+stack.map( (unique >> 1) + 16, NULL); // Pre-grow the list
+if (!schedule_early(visited, stack)) {
+// Bailout without retry
+C->record_method_not_compilable("early schedule failed");
+return;
+}
+// Build Def-Use edges.
+proj_list.push(_root);        // Add real root as another root
+proj_list.pop();
+// Compute the latency information (via backwards walk) for all the
+// instructions in the graph
+GrowableArray<uint> node_latency;
+_node_latency = node_latency;
+if( C->do_scheduling() )
+ComputeLatenciesBackwards(visited, stack);
+// Now schedule all codes as LATE as possible.  This is the LCA in the
+// dominator tree of all USES of a value.  Pick the block with the least
+// loop nesting depth that is lowest in the dominator tree.
+// ( visited.Clear() called in schedule_late()->Node_Backward_Iterator() )
+schedule_late(visited, stack);
+if( C->failing() ) {
+// schedule_late fails only when graph is incorrect.
+assert(!VerifyGraphEdges, "verification should have failed");
+return;
+}
+unique = C->unique();
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print("\n---- Detect implicit null checks ----\n");
+}
+#endif
+// Detect implicit-null-check opportunities.  Basically, find NULL checks
+// with suitable memory ops nearby.  Use the memory op to do the NULL check.
+// I can generate a memory op if there is not one nearby.
+if (C->is_method_compilation()) {
+// Don't do it for natives, adapters, or runtime stubs
+int allowed_reasons = 0;
+// ...and don't do it when there have been too many traps, globally.
+for (int reason = (int)Deoptimization::Reason_none+1;
+reason < Compile::trapHistLength; reason++) {
+assert(reason < BitsPerInt, "recode bit map");
+if (!C->too_many_traps((Deoptimization::DeoptReason) reason))
+allowed_reasons |= nth_bit(reason);
+}
+// By reversing the loop direction we get a very minor gain on mpegaudio.
+// Feel free to revert to a forward loop for clarity.
+// for( int i=0; i < (int)matcher._null_check_tests.size(); i+=2 ) {
+for( int i= matcher._null_check_tests.size()-2; i>=0; i-=2 ) {
+Node *proj = matcher._null_check_tests[i  ];
+Node *val  = matcher._null_check_tests[i+1];
+_bbs[proj->_idx]->implicit_null_check(this, proj, val, allowed_reasons);
+// The implicit_null_check will only perform the transformation
+// if the null branch is truly uncommon, *and* it leads to an
+// uncommon trap.  Combined with the too_many_traps guards
+// above, this prevents SEGV storms reported in 6366351,
+// by recompiling offending methods without this optimization.
+}
+}
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print("\n---- Start Local Scheduling ----\n");
+}
+#endif
+// Schedule locally.  Right now a simple topological sort.
+// Later, do a real latency aware scheduler.
+int *ready_cnt = NEW_RESOURCE_ARRAY(int,C->unique());
+memset( ready_cnt, -1, C->unique() * sizeof(int) );
+visited.Clear();
+for (i = 0; i < _num_blocks; i++) {
+if (!_blocks[i]->schedule_local(this, matcher, ready_cnt, visited)) {
+if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) {
+C->record_method_not_compilable("local schedule failed");
+}
+return;
+}
+}
+// If we inserted any instructions between a Call and his CatchNode,
+// clone the instructions on all paths below the Catch.
+for( i=0; i < _num_blocks; i++ )
+_blocks[i]->call_catch_cleanup(_bbs);
+#ifndef PRODUCT
+if (trace_opto_pipelining()) {
+tty->print("\n---- After GlobalCodeMotion ----\n");
+for (uint i = 0; i < _num_blocks; i++) {
+_blocks[i]->dump();
+}
+}
+#endif
+}
+//------------------------------Estimate_Block_Frequency-----------------------
+// Estimate block frequencies based on IfNode probabilities.
+void PhaseCFG::Estimate_Block_Frequency() {
+int cnts = C->method() ? C->method()->interpreter_invocation_count() : 1;
+// Most of our algorithms will die horribly if frequency can become
+// negative so make sure cnts is a sane value.
+if( cnts <= 0 ) cnts = 1;
+float f = (float)cnts/(float)FreqCountInvocations;
+// Create the loop tree and calculate loop depth.
+_root_loop = create_loop_tree();
+_root_loop->compute_loop_depth(0);
+// Compute block frequency of each block, relative to a single loop entry.
+_root_loop->compute_freq();
+// Adjust all frequencies to be relative to a single method entry
+_root_loop->_freq = f * 1.0;
+_root_loop->scale_freq();
+// force paths ending at uncommon traps to be infrequent
+Block_List worklist;
+Block* root_blk = _blocks[0];
+for (uint i = 0; i < root_blk->num_preds(); i++) {
+Block *pb = _bbs[root_blk->pred(i)->_idx];
+if (pb->has_uncommon_code()) {
+worklist.push(pb);
+}
+}
+while (worklist.size() > 0) {
+Block* uct = worklist.pop();
+uct->_freq = PROB_MIN;
+for (uint i = 0; i < uct->num_preds(); i++) {
+Block *pb = _bbs[uct->pred(i)->_idx];
+if (pb->_num_succs == 1 && pb->_freq > PROB_MIN) {
+worklist.push(pb);
+}
+}
+}
+#ifndef PRODUCT
+if (PrintCFGBlockFreq) {
+tty->print_cr("CFG Block Frequencies");
+_root_loop->dump_tree();
+if (Verbose) {
+tty->print_cr("PhaseCFG dump");
+dump();
+tty->print_cr("Node dump");
+_root->dump(99999);
+}
+}
+#endif
+}
+//----------------------------create_loop_tree--------------------------------
+// Create a loop tree from the CFG
+CFGLoop* PhaseCFG::create_loop_tree() {
+#ifdef ASSERT
+assert( _blocks[0] == _broot, "" );
+for (uint i = 0; i < _num_blocks; i++ ) {
+Block *b = _blocks[i];
+// Check that _loop field are clear...we could clear them if not.
+assert(b->_loop == NULL, "clear _loop expected");
+// Sanity check that the RPO numbering is reflected in the _blocks array.
+// It doesn't have to be for the loop tree to be built, but if it is not,
+// then the blocks have been reordered since dom graph building...which
+// may question the RPO numbering
+assert(b->_rpo == i, "unexpected reverse post order number");
+}
+#endif
+int idct = 0;
+CFGLoop* root_loop = new CFGLoop(idct++);
+Block_List worklist;
+// Assign blocks to loops
+for(uint i = _num_blocks - 1; i > 0; i-- ) { // skip Root block
+Block *b = _blocks[i];
+if (b->head()->is_Loop()) {
+Block* loop_head = b;
+assert(loop_head->num_preds() - 1 == 2, "loop must have 2 predecessors");
+Node* tail_n = loop_head->pred(LoopNode::LoopBackControl);
+Block* tail = _bbs[tail_n->_idx];
+// Defensively filter out Loop nodes for non-single-entry loops.
+// For all reasonable loops, the head occurs before the tail in RPO.
+if (i <= tail->_rpo) {
+// The tail and (recursive) predecessors of the tail
+// are made members of a new loop.
+assert(worklist.size() == 0, "nonempty worklist");
+CFGLoop* nloop = new CFGLoop(idct++);
+assert(loop_head->_loop == NULL, "just checking");
+loop_head->_loop = nloop;
+// Add to nloop so push_pred() will skip over inner loops
+nloop->add_member(loop_head);
+nloop->push_pred(loop_head, LoopNode::LoopBackControl, worklist, _bbs);
+while (worklist.size() > 0) {
+Block* member = worklist.pop();
+if (member != loop_head) {
+for (uint j = 1; j < member->num_preds(); j++) {
+nloop->push_pred(member, j, worklist, _bbs);
+}
+}
+}
+}
+}
+}
+// Create a member list for each loop consisting
+// of both blocks and (immediate child) loops.
+for (uint i = 0; i < _num_blocks; i++) {
+Block *b = _blocks[i];
+CFGLoop* lp = b->_loop;
+if (lp == NULL) {
+// Not assigned to a loop. Add it to the method's pseudo loop.
+b->_loop = root_loop;
+lp = root_loop;
+}
+if (lp == root_loop || b != lp->head()) { // loop heads are already members
+lp->add_member(b);
+}
+if (lp != root_loop) {
+if (lp->parent() == NULL) {
+// Not a nested loop. Make it a child of the method's pseudo loop.
+root_loop->add_nested_loop(lp);
+}
+if (b == lp->head()) {
+// Add nested loop to member list of parent loop.
+lp->parent()->add_member(lp);
+}
+}
+}
+return root_loop;
+}
+//------------------------------push_pred--------------------------------------
+void CFGLoop::push_pred(Block* blk, int i, Block_List& worklist, Block_Array& node_to_blk) {
+Node* pred_n = blk->pred(i);
+Block* pred = node_to_blk[pred_n->_idx];
+CFGLoop *pred_loop = pred->_loop;
+if (pred_loop == NULL) {
+// Filter out blocks for non-single-entry loops.
+// For all reasonable loops, the head occurs before the tail in RPO.
+if (pred->_rpo > head()->_rpo) {
+pred->_loop = this;
+worklist.push(pred);
+}
+} else if (pred_loop != this) {
+// Nested loop.
+while (pred_loop->_parent != NULL && pred_loop->_parent != this) {
+pred_loop = pred_loop->_parent;
+}
+// Make pred's loop be a child
+if (pred_loop->_parent == NULL) {
+add_nested_loop(pred_loop);
+// Continue with loop entry predecessor.
+Block* pred_head = pred_loop->head();
+assert(pred_head->num_preds() - 1 == 2, "loop must have 2 predecessors");
+assert(pred_head != head(), "loop head in only one loop");
+push_pred(pred_head, LoopNode::EntryControl, worklist, node_to_blk);
+} else {
+assert(pred_loop->_parent == this && _parent == NULL, "just checking");
+}
+}
+}
+//------------------------------add_nested_loop--------------------------------
+// Make cl a child of the current loop in the loop tree.
+void CFGLoop::add_nested_loop(CFGLoop* cl) {
+assert(_parent == NULL, "no parent yet");
+assert(cl != this, "not my own parent");
+cl->_parent = this;
+CFGLoop* ch = _child;
+if (ch == NULL) {
+_child = cl;
+} else {
+while (ch->_sibling != NULL) { ch = ch->_sibling; }
+ch->_sibling = cl;
+}
+}
+//------------------------------compute_loop_depth-----------------------------
+// Store the loop depth in each CFGLoop object.
+// Recursively walk the children to do the same for them.
+void CFGLoop::compute_loop_depth(int depth) {
+_depth = depth;
+CFGLoop* ch = _child;
+while (ch != NULL) {
+ch->compute_loop_depth(depth + 1);
+ch = ch->_sibling;
+}
+}
+//------------------------------compute_freq-----------------------------------
+// Compute the frequency of each block and loop, relative to a single entry
+// into the dominating loop head.
+void CFGLoop::compute_freq() {
+// Bottom up traversal of loop tree (visit inner loops first.)
+// Set loop head frequency to 1.0, then transitively
+// compute frequency for all successors in the loop,
+// as well as for each exit edge.  Inner loops are
+// treated as single blocks with loop exit targets
+// as the successor blocks.
+// Nested loops first
+CFGLoop* ch = _child;
+while (ch != NULL) {
+ch->compute_freq();
+ch = ch->_sibling;
+}
+assert (_members.length() > 0, "no empty loops");
+Block* hd = head();
+hd->_freq = 1.0f;
+for (int i = 0; i < _members.length(); i++) {
+CFGElement* s = _members.at(i);
+float freq = s->_freq;
+if (s->is_block()) {
+Block* b = s->as_Block();
+for (uint j = 0; j < b->_num_succs; j++) {
+Block* sb = b->_succs[j];
+update_succ_freq(sb, freq * b->succ_prob(j));
+}
+} else {
+CFGLoop* lp = s->as_CFGLoop();
+assert(lp->_parent == this, "immediate child");
+for (int k = 0; k < lp->_exits.length(); k++) {
+Block* eb = lp->_exits.at(k).get_target();
+float prob = lp->_exits.at(k).get_prob();
+update_succ_freq(eb, freq * prob);
+}
+}
+}
+#if 0
+// Raise frequency of the loop backedge block, in an effort
+// to keep it empty.  Skip the method level "loop".
+if (_parent != NULL) {
+CFGElement* s = _members.at(_members.length() - 1);
+if (s->is_block()) {
+Block* bk = s->as_Block();
+if (bk->_num_succs == 1 && bk->_succs[0] == hd) {
+// almost any value >= 1.0f works
+// FIXME: raw constant
+bk->_freq = 1.05f;
+}
+}
+}
+#endif
+// For all loops other than the outer, "method" loop,
+// sum and normalize the exit probability. The "method" loop
+// should keep the initial exit probability of 1, so that
+// inner blocks do not get erroneously scaled.
+if (_depth != 0) {
+// Total the exit probabilities for this loop.
+float exits_sum = 0.0f;
+for (int i = 0; i < _exits.length(); i++) {
+exits_sum += _exits.at(i).get_prob();
+}
+// Normalize the exit probabilities. Until now, the
+// probabilities estimate the possibility of exit per
+// a single loop iteration; afterward, they estimate
+// the probability of exit per loop entry.
+for (int i = 0; i < _exits.length(); i++) {
+Block* et = _exits.at(i).get_target();
+float new_prob = _exits.at(i).get_prob() / exits_sum;
+BlockProbPair bpp(et, new_prob);
+_exits.at_put(i, bpp);
+}
+// Save the total, but guard against unreasoable probability,
+// as the value is used to estimate the loop trip count.
+// An infinite trip count would blur relative block
+// frequencies.
+if (exits_sum > 1.0f) exits_sum = 1.0;
+if (exits_sum < PROB_MIN) exits_sum = PROB_MIN;
+_exit_prob = exits_sum;
+}
+}
+//------------------------------succ_prob-------------------------------------
+// Determine the probability of reaching successor 'i' from the receiver block.
+float Block::succ_prob(uint i) {
+int eidx = end_idx();
+Node *n = _nodes[eidx];  // Get ending Node
+int op = n->is_Mach() ? n->as_Mach()->ideal_Opcode() : n->Opcode();
+// Switch on branch type
+switch( op ) {
+case Op_CountedLoopEnd:
+case Op_If: {
+assert (i < 2, "just checking");
+// Conditionals pass on only part of their frequency
+float prob  = n->as_MachIf()->_prob;
+assert(prob >= 0.0 && prob <= 1.0, "out of range probability");
+// If succ[i] is the FALSE branch, invert path info
+if( _nodes[i + eidx + 1]->Opcode() == Op_IfFalse ) {
+return 1.0f - prob; // not taken
+} else {
+return prob; // taken
+}
+}
+case Op_Jump:
+// Divide the frequency between all successors evenly
+return 1.0f/_num_succs;
+case Op_Catch: {
+const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj();
+if (ci->_con == CatchProjNode::fall_through_index) {
+// Fall-thru path gets the lion's share.
+return 1.0f - PROB_UNLIKELY_MAG(5)*_num_succs;
+} else {
+// Presume exceptional paths are equally unlikely
+return PROB_UNLIKELY_MAG(5);
+}
+}
+case Op_Root:
+case Op_Goto:
+// Pass frequency straight thru to target
+return 1.0f;
+case Op_NeverBranch:
+return 0.0f;
+case Op_TailCall:
+case Op_TailJump:
+case Op_Return:
+case Op_Halt:
+case Op_Rethrow:
+// Do not push out freq to root block
+return 0.0f;
+default:
+ShouldNotReachHere();
+}
+return 0.0f;
+}
+//------------------------------update_succ_freq-------------------------------
+// Update the appropriate frequency associated with block 'b', a succesor of
+// a block in this loop.
+void CFGLoop::update_succ_freq(Block* b, float freq) {
+if (b->_loop == this) {
+if (b == head()) {
+// back branch within the loop
+// Do nothing now, the loop carried frequency will be
+// adjust later in scale_freq().
+} else {
+// simple branch within the loop
+b->_freq += freq;
+}
+} else if (!in_loop_nest(b)) {
+// branch is exit from this loop
+BlockProbPair bpp(b, freq);
+_exits.append(bpp);
+} else {
+// branch into nested loop
+CFGLoop* ch = b->_loop;
+ch->_freq += freq;
+}
+}
+//------------------------------in_loop_nest-----------------------------------
+// Determine if block b is in the receiver's loop nest.
+bool CFGLoop::in_loop_nest(Block* b) {
+int depth = _depth;
+CFGLoop* b_loop = b->_loop;
+int b_depth = b_loop->_depth;
+if (depth == b_depth) {
+return true;
+}
+while (b_depth > depth) {
+b_loop = b_loop->_parent;
+b_depth = b_loop->_depth;
+}
+return b_loop == this;
+}
+//------------------------------scale_freq-------------------------------------
+// Scale frequency of loops and blocks by trip counts from outer loops
+// Do a top down traversal of loop tree (visit outer loops first.)
+void CFGLoop::scale_freq() {
+float loop_freq = _freq * trip_count();
+for (int i = 0; i < _members.length(); i++) {
+CFGElement* s = _members.at(i);
+s->_freq *= loop_freq;
+}
+CFGLoop* ch = _child;
+while (ch != NULL) {
+ch->scale_freq();
+ch = ch->_sibling;
+}
+}
+#ifndef PRODUCT
+//------------------------------dump_tree--------------------------------------
+void CFGLoop::dump_tree() const {
+dump();
+if (_child != NULL)   _child->dump_tree();
+if (_sibling != NULL) _sibling->dump_tree();
+}
+//------------------------------dump-------------------------------------------
+void CFGLoop::dump() const {
+for (int i = 0; i < _depth; i++) tty->print("   ");
+tty->print("%s: %d  trip_count: %6.0f freq: %6.0f\n",
+_depth == 0 ? "Method" : "Loop", _id, trip_count(), _freq);
+for (int i = 0; i < _depth; i++) tty->print("   ");
+tty->print("         members:", _id);
+int k = 0;
+for (int i = 0; i < _members.length(); i++) {
+if (k++ >= 6) {
+tty->print("\n              ");
+for (int j = 0; j < _depth+1; j++) tty->print("   ");
+k = 0;
+}
+CFGElement *s = _members.at(i);
+if (s->is_block()) {
+Block *b = s->as_Block();
+tty->print(" B%d(%6.3f)", b->_pre_order, b->_freq);
+} else {
+CFGLoop* lp = s->as_CFGLoop();
+tty->print(" L%d(%6.3f)", lp->_id, lp->_freq);
+}
+}
+tty->print("\n");
+for (int i = 0; i < _depth; i++) tty->print("   ");
+tty->print("         exits:  ");
+k = 0;
+for (int i = 0; i < _exits.length(); i++) {
+if (k++ >= 7) {
+tty->print("\n              ");
+for (int j = 0; j < _depth+1; j++) tty->print("   ");
+k = 0;
+}
+Block *blk = _exits.at(i).get_target();
+float prob = _exits.at(i).get_prob();
+tty->print(" ->%d@%d%%", blk->_pre_order, (int)(prob*100));
+}
+tty->print("\n");
+}
+#endif

Mercurial > hg > graal-jvmci-8

comparison src/share/vm/opto/gcm.cpp @ 0:a61af66fc99e jdk7-b24