| /* |
| * 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 "opto/block.hpp" |
| #include "opto/c2compiler.hpp" |
| #include "opto/callnode.hpp" |
| #include "opto/cfgnode.hpp" |
| #include "opto/machnode.hpp" |
| #include "opto/opcodes.hpp" |
| #include "opto/phaseX.hpp" |
| #include "opto/rootnode.hpp" |
| #include "opto/runtime.hpp" |
| #include "opto/chaitin.hpp" |
| #include "runtime/deoptimization.hpp" |
| |
| // Portions of code courtesy of Clifford Click |
| |
| // Optimization - Graph Style |
| |
| // To avoid float value underflow |
| #define MIN_BLOCK_FREQUENCY 1.e-35f |
| |
| //----------------------------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, |
| map_node_to_block(n, 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 = get_block_for_node(use); |
| if (buse != b) { // In wrong block? |
| if (buse != NULL) { |
| buse->find_remove(use); // Remove from wrong block |
| } |
| map_node_to_block(use, b); |
| b->add_inst(use); |
| } |
| } |
| } |
| } |
| |
| //----------------------------replace_block_proj_ctrl------------------------- |
| // Nodes that have is_block_proj() nodes as their control need to use |
| // the appropriate Region for their actual block as their control since |
| // the projection will be in a predecessor block. |
| void PhaseCFG::replace_block_proj_ctrl( Node *n ) { |
| const Node *in0 = n->in(0); |
| assert(in0 != NULL, "Only control-dependent"); |
| const Node *p = in0->is_block_proj(); |
| if (p != NULL && p != n) { // Control from a block projection? |
| assert(!n->pinned() || n->is_MachConstantBase(), "only pinned MachConstantBase node is expected here"); |
| // Find trailing Region |
| Block *pb = get_block_for_node(in0); // Block-projection already has basic block |
| uint j = 0; |
| if (pb->_num_succs != 1) { // More then 1 successor? |
| // Search for successor |
| uint max = pb->number_of_nodes(); |
| assert( max > 1, "" ); |
| uint start = max - pb->_num_succs; |
| // Find which output path belongs to projection |
| for (j = start; j < max; j++) { |
| if( pb->get_node(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()); |
| } |
| } |
| |
| bool PhaseCFG::is_dominator(Node* dom_node, Node* node) { |
| if (dom_node == node) { |
| return true; |
| } |
| Block* d = get_block_for_node(dom_node); |
| Block* n = get_block_for_node(node); |
| if (d == n) { |
| if (dom_node->is_block_start()) { |
| return true; |
| } |
| if (node->is_block_start()) { |
| return false; |
| } |
| if (dom_node->is_block_proj()) { |
| return false; |
| } |
| if (node->is_block_proj()) { |
| return true; |
| } |
| #ifdef ASSERT |
| node->dump(); |
| dom_node->dump(); |
| #endif |
| fatal("unhandled"); |
| return false; |
| } |
| return d->dom_lca(n) == d; |
| } |
| |
| //------------------------------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->live_nodes()+8 to avoid frequent realloc |
| GrowableArray <Node *> spstack(C->live_nodes() + 8); |
| spstack.push(_root); |
| while (spstack.is_nonempty()) { |
| Node* node = spstack.pop(); |
| if (!visited.test_set(node->_idx)) { // Test node and flag it as visited |
| if (node->pinned() && !has_block(node)) { // Pinned? Nail it down! |
| assert(node->in(0), "pinned Node must have Control"); |
| // Before setting block replace block_proj control edge |
| replace_block_proj_ctrl(node); |
| Node* input = node->in(0); |
| while (!input->is_block_start()) { |
| input = input->in(0); |
| } |
| Block* block = get_block_for_node(input); // Basic block of controlling input |
| schedule_node_into_block(node, block); |
| } |
| |
| // If the node has precedence edges (added when CastPP nodes are |
| // removed in final_graph_reshaping), fix the control of the |
| // node to cover the precedence edges and remove the |
| // dependencies. |
| Node* n = NULL; |
| for (uint i = node->len()-1; i >= node->req(); i--) { |
| Node* m = node->in(i); |
| if (m == NULL) continue; |
| // Skip the precedence edge if the test that guarded a CastPP: |
| // - was optimized out during escape analysis |
| // (OptimizePtrCompare): the CastPP's control isn't an end of |
| // block. |
| // - is moved in the branch of a dominating If: the control of |
| // the CastPP is then a Region. |
| if (m->is_block_proj() || m->is_block_start()) { |
| node->rm_prec(i); |
| if (n == NULL) { |
| n = m; |
| } else { |
| assert(is_dominator(n, m) || is_dominator(m, n), "one must dominate the other"); |
| n = is_dominator(n, m) ? m : n; |
| } |
| } |
| } |
| if (n != NULL) { |
| assert(node->in(0), "control should have been set"); |
| assert(is_dominator(n, node->in(0)) || is_dominator(node->in(0), n), "one must dominate the other"); |
| if (!is_dominator(n, node->in(0))) { |
| node->set_req(0, n); |
| } |
| } |
| |
| // process all inputs that are non NULL |
| for (int i = node->req() - 1; i >= 0; --i) { |
| if (node->in(i) != NULL) { |
| spstack.push(node->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, const PhaseCFG* cfg) { |
| 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 = cfg->get_block_for_node(inn); |
| 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, const PhaseCFG* cfg) { |
| // 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 = cfg->get_block_for_node(inn); |
| 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, cfg)); |
| 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_Stack &roots) { |
| // Allocate stack with enough space to avoid frequent realloc |
| Node_Stack nstack(roots.size() + 8); |
| // _root will be processed among C->top() inputs |
| roots.push(C->top(), 0); |
| 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* parent_node = roots.node(); |
| uint input_index = 0; |
| roots.pop(); |
| |
| while (true) { |
| if (input_index == 0) { |
| // Fixup some control. Constants without control get attached |
| // to root and nodes that use is_block_proj() nodes should be attached |
| // to the region that starts their block. |
| const Node* control_input = parent_node->in(0); |
| if (control_input != NULL) { |
| replace_block_proj_ctrl(parent_node); |
| } else { |
| // Is a constant with NO inputs? |
| if (parent_node->req() == 1) { |
| parent_node->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). |
| |
| // Assume all n's inputs will be processed |
| bool done = true; |
| |
| while (input_index < parent_node->len()) { |
| Node* in = parent_node->in(input_index++); |
| if (in == NULL) { |
| continue; |
| } |
| |
| int is_visited = visited.test_set(in->_idx); |
| if (!has_block(in)) { |
| if (is_visited) { |
| return false; |
| } |
| // Save parent node and next input's index. |
| nstack.push(parent_node, input_index); |
| // Process current input now. |
| parent_node = in; |
| input_index = 0; |
| // Not all n's inputs processed. |
| done = false; |
| break; |
| } else if (!is_visited) { |
| // Visit this guy later, using worklist |
| roots.push(in, 0); |
| } |
| } |
| |
| 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 (!parent_node->pinned()) { |
| // Set earliest legal block. |
| Block* earliest_block = find_deepest_input(parent_node, this); |
| map_node_to_block(parent_node, earliest_block); |
| } else { |
| assert(get_block_for_node(parent_node) == get_block_for_node(parent_node->in(0)), "Pinned Node should be at the same block as its control edge"); |
| } |
| |
| 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. |
| parent_node = nstack.node(); |
| input_index = nstack.index(); |
| nstack.pop(); |
| } |
| } |
| } |
| 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, const PhaseCFG* cfg) { |
| Block* buse = cfg->get_block_for_node(use); |
| 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 = cfg->get_block_for_node(buse->pred(j)); |
| 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, const PhaseCFG* cfg) { |
| 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 |
| |
| // 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); |
| if (LCA == mid) |
| continue; // Don't mark as visited to avoid early termination. |
| } else { |
| // Keep searching through this block's predecessors. |
| for (uint j = 1, jmax = mid->num_preds(); j < jmax; j++) { |
| Block* mid_parent = cfg->get_block_for_node(mid->pred(j)); |
| worklist.push(mid_parent); |
| } |
| } |
| mid->set_raise_LCA_visited(mark); |
| } |
| 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, const PhaseCFG* cfg) { |
| 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 = cfg->get_block_for_node(mem_inputs[i]); |
| 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, cfg)); |
| 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. |
| int 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"); |
| assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrEquals), |
| "String equals is a 'load' that does not conflict with any stores"); |
| assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrIndexOf), |
| "String indexOf is a 'load' that does not conflict with any stores"); |
| assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrIndexOfChar), |
| "String indexOfChar is a 'load' that does not conflict with any stores"); |
| assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_AryEq), |
| "Arrays equals is a 'load' that does not conflict with any stores"); |
| assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_HasNegatives), |
| "HasNegatives is a '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 = get_block_for_node(load); |
| |
| // 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, this); |
| } |
| |
| 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 worklist_visited(area); // visited mergemem nodes |
| Node_List non_early_stores(area); // all relevant stores outside of early |
| bool must_raise_LCA = false; |
| |
| #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_visited.push(initial_mem); |
| worklist_mem.push(NULL); |
| 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. |
| if (store == initial_mem) |
| initial_mem = NULL; // only process initial memory once |
| |
| 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 j = worklist_visited.size(); |
| for (; j > 0; j--) { |
| if (worklist_visited.at(j-1) == store) break; |
| } |
| if (j > 0) continue; // already on work list; do not repeat |
| worklist_visited.push(store); |
| } |
| 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 = get_block_for_node(store); |
| 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 = get_block_for_node(store_block->pred(j)); |
| 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 preceding 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; |
| } else { |
| // anti-dependent upon PHI pinned below 'early', no edge needed |
| LCA = early; // but can not schedule below 'early' |
| } |
| } |
| } |
| 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, this); |
| 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 = get_block_for_node(store); |
| 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_Stack &stack, PhaseCFG &cfg); |
| |
| // Postincrement operator to iterate over the nodes |
| Node *next(); |
| |
| private: |
| VectorSet &_visited; |
| Node_Stack &_stack; |
| PhaseCFG &_cfg; |
| }; |
| |
| // Constructor for the Node_Backward_Iterator |
| Node_Backward_Iterator::Node_Backward_Iterator( Node *root, VectorSet &visited, Node_Stack &stack, PhaseCFG &cfg) |
| : _visited(visited), _stack(stack), _cfg(cfg) { |
| // The stack should contain exactly the root |
| stack.clear(); |
| stack.push(root, root->outcnt()); |
| |
| // 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; |
| |
| // I visit unvisited not-anti-dependence users first, then anti-dependent |
| // children next. I iterate backwards to support removal of nodes. |
| // The stack holds states consisting of 3 values: |
| // current Def node, flag which indicates 1st/2nd pass, index of current out edge |
| Node *self = (Node*)(((uintptr_t)_stack.node()) & ~1); |
| bool iterate_anti_dep = (((uintptr_t)_stack.node()) & 1); |
| uint idx = MIN2(_stack.index(), self->outcnt()); // Support removal of nodes. |
| _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. |
| const Node* src = self->is_Proj() ? self->in(0) : self; |
| uint src_rpo = _cfg.get_block_for_node(src)->_rpo; |
| |
| // Schedule all nodes in a post-order visit |
| Node *unvisited = NULL; // Unvisited anti-dependent Node, if any |
| |
| // Scan for unvisited nodes |
| while (idx > 0) { |
| // For all uses, schedule late |
| Node* n = self->raw_out(--idx); // 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 = _cfg.get_block_for_node(use)->_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 |
| // 1st pass: No such nodes, 2nd pass: Only such nodes. |
| if (n->needs_anti_dependence_check() == iterate_anti_dep) { |
| unvisited = n; // Found unvisited |
| break; |
| } |
| } |
| |
| // Did I find an unvisited not-anti-dependent Node? |
| if (!unvisited) { |
| if (!iterate_anti_dep) { |
| // 2nd pass: Iterate over nodes which needs_anti_dependence_check. |
| iterate_anti_dep = true; |
| idx = self->outcnt(); |
| continue; |
| } |
| 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((Node*)((uintptr_t)self | (uintptr_t)iterate_anti_dep), idx); |
| self = unvisited; |
| iterate_anti_dep = false; |
| idx = self->outcnt(); |
| } // End recursion loop |
| |
| return self; |
| } |
| |
| //------------------------------ComputeLatenciesBackwards---------------------- |
| // Compute the latency of all the instructions. |
| void PhaseCFG::compute_latencies_backwards(VectorSet &visited, Node_Stack &stack) { |
| #ifndef PRODUCT |
| if (trace_opto_pipelining()) |
| tty->print("\n#---- ComputeLatenciesBackwards ----\n"); |
| #endif |
| |
| Node_Backward_Iterator iter((Node *)_root, visited, stack, *this); |
| 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, get_latency_for_node(n)); |
| dump(); |
| } |
| #endif |
| |
| if (n->is_Proj()) { |
| n = n->in(0); |
| } |
| |
| if (n->is_Root()) { |
| return; |
| } |
| |
| uint nlen = n->len(); |
| uint use_latency = get_latency_for_node(n); |
| uint use_pre_order = get_block_for_node(n)->_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 = get_block_for_node(def); |
| 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 (get_latency_for_node(def) < current_latency) { |
| set_latency_for_node(def, 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, get_latency_for_node(def)); |
| } |
| #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 = get_block_for_node(def)->_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 = get_block_for_node(use)->_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 = get_latency_for_node(use); |
| |
| 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, get_latency_for_node(n)); |
| 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; |
| } |
| |
| set_latency_for_node(n, 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 = get_latency_for_node(self); |
| uint start_latency = get_latency_for_node(LCA->head()); |
| uint end_latency = get_latency_for_node(LCA->get_node(LCA->end_idx())); |
| bool in_latency = (target <= start_latency); |
| const Block* root_block = get_block_for_node(_root); |
| |
| // 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: ", get_latency_for_node(self)); |
| self->dump(); |
| tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g", |
| LCA->_pre_order, |
| LCA->head()->_idx, |
| start_latency, |
| LCA->get_node(LCA->end_idx())->_idx, |
| end_latency, |
| least_freq); |
| } |
| #endif |
| |
| int cand_cnt = 0; // number of candidates tried |
| |
| // 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 = get_latency_for_node(LCA->head()); |
| uint end_idx = LCA->end_idx(); |
| uint end_lat = get_latency_for_node(LCA->get_node(end_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->head()->_idx, start_lat, end_idx, end_lat, LCA_freq); |
| } |
| #endif |
| cand_cnt++; |
| if (LCA_freq < least_freq || // Better Frequency |
| (StressGCM && Compile::randomized_select(cand_cnt)) || // Should be randomly accepted in stress mode |
| (!StressGCM && // Otherwise, choose with latency |
| !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 |
| set_latency_for_node(self, 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_Stack &stack) { |
| #ifndef PRODUCT |
| if (trace_opto_pipelining()) |
| tty->print("\n#---- schedule_late ----\n"); |
| #endif |
| |
| Node_Backward_Iterator iter((Node *)_root, visited, stack, *this); |
| Node *self; |
| |
| // Walk over all the nodes from last to first |
| while (self = iter.next()) { |
| Block* early = get_block_for_node(self); // 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->is_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); |
| #ifdef ASSERT |
| _raw_oops.push(def); |
| #endif |
| 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, this); |
| } |
| } // (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()) { |
| map_node_to_block(self, 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. |
| // In stress mode, try to hoist even the single operations. |
| bool try_to_hoist = StressGCM || (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::global_code_motion() { |
| ResourceMark rm; |
| |
| #ifndef PRODUCT |
| if (trace_opto_pipelining()) { |
| tty->print("\n---- Start GlobalCodeMotion ----\n"); |
| } |
| #endif |
| |
| // Initialize the node to block mapping for things on the proj_list |
| for (uint i = 0; i < _matcher.number_of_projections(); i++) { |
| unmap_node_from_block(_matcher.get_projection(i)); |
| } |
| |
| // Set the basic block for Nodes pinned into blocks |
| Arena* arena = Thread::current()->resource_area(); |
| VectorSet visited(arena); |
| 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_Stack stack(arena, (C->live_nodes() >> 2) + 16); // pre-grow |
| if (!schedule_early(visited, stack)) { |
| // Bailout without retry |
| C->record_method_not_compilable("early schedule failed"); |
| return; |
| } |
| |
| // Build Def-Use edges. |
| // Compute the latency information (via backwards walk) for all the |
| // instructions in the graph |
| _node_latency = new GrowableArray<uint>(); // resource_area allocation |
| |
| if (C->do_scheduling()) { |
| compute_latencies_backwards(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; |
| } |
| |
| #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()) { |
| // 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]; |
| Block* block = get_block_for_node(proj); |
| implicit_null_check(block, proj, val, C->allowed_deopt_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. |
| } |
| } |
| |
| bool block_size_threshold_ok = false; |
| intptr_t *recalc_pressure_nodes = NULL; |
| if (OptoRegScheduling) { |
| for (uint i = 0; i < number_of_blocks(); i++) { |
| Block* block = get_block(i); |
| if (block->number_of_nodes() > 10) { |
| block_size_threshold_ok = true; |
| break; |
| } |
| } |
| } |
| |
| // Enabling the scheduler for register pressure plus finding blocks of size to schedule for it |
| // is key to enabling this feature. |
| PhaseChaitin regalloc(C->unique(), *this, _matcher, true); |
| ResourceArea live_arena; // Arena for liveness |
| ResourceMark rm_live(&live_arena); |
| PhaseLive live(*this, regalloc._lrg_map.names(), &live_arena, true); |
| PhaseIFG ifg(&live_arena); |
| if (OptoRegScheduling && block_size_threshold_ok) { |
| regalloc.mark_ssa(); |
| Compile::TracePhase tp("computeLive", &timers[_t_computeLive]); |
| rm_live.reset_to_mark(); // Reclaim working storage |
| IndexSet::reset_memory(C, &live_arena); |
| uint node_size = regalloc._lrg_map.max_lrg_id(); |
| ifg.init(node_size); // Empty IFG |
| regalloc.set_ifg(ifg); |
| regalloc.set_live(live); |
| regalloc.gather_lrg_masks(false); // Collect LRG masks |
| live.compute(node_size); // Compute liveness |
| |
| recalc_pressure_nodes = NEW_RESOURCE_ARRAY(intptr_t, node_size); |
| for (uint i = 0; i < node_size; i++) { |
| recalc_pressure_nodes[i] = 0; |
| } |
| } |
| _regalloc = ®alloc; |
| |
| #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. |
| GrowableArray<int> ready_cnt(C->unique(), C->unique(), -1); |
| visited.Clear(); |
| for (uint i = 0; i < number_of_blocks(); i++) { |
| Block* block = get_block(i); |
| if (!schedule_local(block, ready_cnt, visited, recalc_pressure_nodes)) { |
| if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) { |
| C->record_method_not_compilable("local schedule failed"); |
| } |
| _regalloc = NULL; |
| return; |
| } |
| } |
| _regalloc = NULL; |
| |
| // If we inserted any instructions between a Call and his CatchNode, |
| // clone the instructions on all paths below the Catch. |
| for (uint i = 0; i < number_of_blocks(); i++) { |
| Block* block = get_block(i); |
| call_catch_cleanup(block); |
| } |
| |
| #ifndef PRODUCT |
| if (trace_opto_pipelining()) { |
| tty->print("\n---- After GlobalCodeMotion ----\n"); |
| for (uint i = 0; i < number_of_blocks(); i++) { |
| Block* block = get_block(i); |
| block->dump(); |
| } |
| } |
| #endif |
| // Dead. |
| _node_latency = (GrowableArray<uint> *)0xdeadbeef; |
| } |
| |
| bool PhaseCFG::do_global_code_motion() { |
| |
| build_dominator_tree(); |
| if (C->failing()) { |
| return false; |
| } |
| |
| NOT_PRODUCT( C->verify_graph_edges(); ) |
| |
| estimate_block_frequency(); |
| |
| global_code_motion(); |
| |
| if (C->failing()) { |
| return false; |
| } |
| |
| return true; |
| } |
| |
| //------------------------------Estimate_Block_Frequency----------------------- |
| // Estimate block frequencies based on IfNode probabilities. |
| void PhaseCFG::estimate_block_frequency() { |
| |
| // Force conditional branches leading to uncommon traps to be unlikely, |
| // not because we get to the uncommon_trap with less relative frequency, |
| // but because an uncommon_trap typically causes a deopt, so we only get |
| // there once. |
| if (C->do_freq_based_layout()) { |
| Block_List worklist; |
| Block* root_blk = get_block(0); |
| for (uint i = 1; i < root_blk->num_preds(); i++) { |
| Block *pb = get_block_for_node(root_blk->pred(i)); |
| if (pb->has_uncommon_code()) { |
| worklist.push(pb); |
| } |
| } |
| while (worklist.size() > 0) { |
| Block* uct = worklist.pop(); |
| if (uct == get_root_block()) { |
| continue; |
| } |
| for (uint i = 1; i < uct->num_preds(); i++) { |
| Block *pb = get_block_for_node(uct->pred(i)); |
| if (pb->_num_succs == 1) { |
| worklist.push(pb); |
| } else if (pb->num_fall_throughs() == 2) { |
| pb->update_uncommon_branch(uct); |
| } |
| } |
| } |
| } |
| |
| // 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 = 1.0; |
| _root_loop->scale_freq(); |
| |
| // Save outmost loop frequency for LRG frequency threshold |
| _outer_loop_frequency = _root_loop->outer_loop_freq(); |
| |
| // force paths ending at uncommon traps to be infrequent |
| if (!C->do_freq_based_layout()) { |
| Block_List worklist; |
| Block* root_blk = get_block(0); |
| for (uint i = 1; i < root_blk->num_preds(); i++) { |
| Block *pb = get_block_for_node(root_blk->pred(i)); |
| if (pb->has_uncommon_code()) { |
| worklist.push(pb); |
| } |
| } |
| while (worklist.size() > 0) { |
| Block* uct = worklist.pop(); |
| uct->_freq = PROB_MIN; |
| for (uint i = 1; i < uct->num_preds(); i++) { |
| Block *pb = get_block_for_node(uct->pred(i)); |
| if (pb->_num_succs == 1 && pb->_freq > PROB_MIN) { |
| worklist.push(pb); |
| } |
| } |
| } |
| } |
| |
| #ifdef ASSERT |
| for (uint i = 0; i < number_of_blocks(); i++) { |
| Block* b = get_block(i); |
| assert(b->_freq >= MIN_BLOCK_FREQUENCY, "Register Allocator requires meaningful block frequency"); |
| } |
| #endif |
| |
| #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(get_block(0) == get_root_block(), "first block should be root block"); |
| for (uint i = 0; i < number_of_blocks(); i++) { |
| Block* block = get_block(i); |
| // Check that _loop field are clear...we could clear them if not. |
| assert(block->_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(block->_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 = number_of_blocks() - 1; i > 0; i-- ) { // skip Root block |
| Block* block = get_block(i); |
| |
| if (block->head()->is_Loop()) { |
| Block* loop_head = block; |
| assert(loop_head->num_preds() - 1 == 2, "loop must have 2 predecessors"); |
| Node* tail_n = loop_head->pred(LoopNode::LoopBackControl); |
| Block* tail = get_block_for_node(tail_n); |
| |
| // 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, this); |
| |
| 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, this); |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| // Create a member list for each loop consisting |
| // of both blocks and (immediate child) loops. |
| for (uint i = 0; i < number_of_blocks(); i++) { |
| Block* block = get_block(i); |
| CFGLoop* lp = block->_loop; |
| if (lp == NULL) { |
| // Not assigned to a loop. Add it to the method's pseudo loop. |
| block->_loop = root_loop; |
| lp = root_loop; |
| } |
| if (lp == root_loop || block != lp->head()) { // loop heads are already members |
| lp->add_member(block); |
| } |
| 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 (block == 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, PhaseCFG* cfg) { |
| Node* pred_n = blk->pred(i); |
| Block* pred = cfg->get_block_for_node(pred_n); |
| 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, cfg); |
| } 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 = 1.0; |
| for (int i = 0; i < _members.length(); i++) { |
| CFGElement* s = _members.at(i); |
| double 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(); |
| double prob = lp->_exits.at(k).get_prob(); |
| update_succ_freq(eb, freq * prob); |
| } |
| } |
| } |
| |
| // 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. |
| double 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 = 0.0f; |
| if (_exits.at(i).get_prob() > 0.0f) { |
| 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 unreasonable 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 = get_node(eidx); // Get ending Node |
| |
| int op = n->Opcode(); |
| if (n->is_Mach()) { |
| if (n->is_MachNullCheck()) { |
| // Can only reach here if called after lcm. The original Op_If is gone, |
| // so we attempt to infer the probability from one or both of the |
| // successor blocks. |
| assert(_num_succs == 2, "expecting 2 successors of a null check"); |
| // If either successor has only one predecessor, then the |
| // probability estimate can be derived using the |
| // relative frequency of the successor and this block. |
| if (_succs[i]->num_preds() == 2) { |
| return _succs[i]->_freq / _freq; |
| } else if (_succs[1-i]->num_preds() == 2) { |
| return 1 - (_succs[1-i]->_freq / _freq); |
| } else { |
| // Estimate using both successor frequencies |
| float freq = _succs[i]->_freq; |
| return freq / (freq + _succs[1-i]->_freq); |
| } |
| } |
| op = n->as_Mach()->ideal_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( get_node(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 = get_node(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; |
| } |
| |
| //------------------------------num_fall_throughs----------------------------- |
| // Return the number of fall-through candidates for a block |
| int Block::num_fall_throughs() { |
| int eidx = end_idx(); |
| Node *n = get_node(eidx); // Get ending Node |
| |
| int op = n->Opcode(); |
| if (n->is_Mach()) { |
| if (n->is_MachNullCheck()) { |
| // In theory, either side can fall-thru, for simplicity sake, |
| // let's say only the false branch can now. |
| return 1; |
| } |
| op = n->as_Mach()->ideal_Opcode(); |
| } |
| |
| // Switch on branch type |
| switch( op ) { |
| case Op_CountedLoopEnd: |
| case Op_If: |
| return 2; |
| |
| case Op_Root: |
| case Op_Goto: |
| return 1; |
| |
| case Op_Catch: { |
| for (uint i = 0; i < _num_succs; i++) { |
| const CatchProjNode *ci = get_node(i + eidx + 1)->as_CatchProj(); |
| if (ci->_con == CatchProjNode::fall_through_index) { |
| return 1; |
| } |
| } |
| return 0; |
| } |
| |
| case Op_Jump: |
| case Op_NeverBranch: |
| case Op_TailCall: |
| case Op_TailJump: |
| case Op_Return: |
| case Op_Halt: |
| case Op_Rethrow: |
| return 0; |
| |
| default: |
| ShouldNotReachHere(); |
| } |
| |
| return 0; |
| } |
| |
| //------------------------------succ_fall_through----------------------------- |
| // Return true if a specific successor could be fall-through target. |
| bool Block::succ_fall_through(uint i) { |
| int eidx = end_idx(); |
| Node *n = get_node(eidx); // Get ending Node |
| |
| int op = n->Opcode(); |
| if (n->is_Mach()) { |
| if (n->is_MachNullCheck()) { |
| // In theory, either side can fall-thru, for simplicity sake, |
| // let's say only the false branch can now. |
| return get_node(i + eidx + 1)->Opcode() == Op_IfFalse; |
| } |
| op = n->as_Mach()->ideal_Opcode(); |
| } |
| |
| // Switch on branch type |
| switch( op ) { |
| case Op_CountedLoopEnd: |
| case Op_If: |
| case Op_Root: |
| case Op_Goto: |
| return true; |
| |
| case Op_Catch: { |
| const CatchProjNode *ci = get_node(i + eidx + 1)->as_CatchProj(); |
| return ci->_con == CatchProjNode::fall_through_index; |
| } |
| |
| case Op_Jump: |
| case Op_NeverBranch: |
| case Op_TailCall: |
| case Op_TailJump: |
| case Op_Return: |
| case Op_Halt: |
| case Op_Rethrow: |
| return false; |
| |
| default: |
| ShouldNotReachHere(); |
| } |
| |
| return false; |
| } |
| |
| //------------------------------update_uncommon_branch------------------------ |
| // Update the probability of a two-branch to be uncommon |
| void Block::update_uncommon_branch(Block* ub) { |
| int eidx = end_idx(); |
| Node *n = get_node(eidx); // Get ending Node |
| |
| int op = n->as_Mach()->ideal_Opcode(); |
| |
| assert(op == Op_CountedLoopEnd || op == Op_If, "must be a If"); |
| assert(num_fall_throughs() == 2, "must be a two way branch block"); |
| |
| // Which successor is ub? |
| uint s; |
| for (s = 0; s <_num_succs; s++) { |
| if (_succs[s] == ub) break; |
| } |
| assert(s < 2, "uncommon successor must be found"); |
| |
| // If ub is the true path, make the proability small, else |
| // ub is the false path, and make the probability large |
| bool invert = (get_node(s + eidx + 1)->Opcode() == Op_IfFalse); |
| |
| // Get existing probability |
| float p = n->as_MachIf()->_prob; |
| |
| if (invert) p = 1.0 - p; |
| if (p > PROB_MIN) { |
| p = PROB_MIN; |
| } |
| if (invert) p = 1.0 - p; |
| |
| n->as_MachIf()->_prob = p; |
| } |
| |
| //------------------------------update_succ_freq------------------------------- |
| // Update the appropriate frequency associated with block 'b', a successor of |
| // a block in this loop. |
| void CFGLoop::update_succ_freq(Block* b, double 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() { |
| double loop_freq = _freq * trip_count(); |
| _freq = loop_freq; |
| for (int i = 0; i < _members.length(); i++) { |
| CFGElement* s = _members.at(i); |
| double block_freq = s->_freq * loop_freq; |
| if (g_isnan(block_freq) || block_freq < MIN_BLOCK_FREQUENCY) |
| block_freq = MIN_BLOCK_FREQUENCY; |
| s->_freq = block_freq; |
| } |
| CFGLoop* ch = _child; |
| while (ch != NULL) { |
| ch->scale_freq(); |
| ch = ch->_sibling; |
| } |
| } |
| |
| // Frequency of outer loop |
| double CFGLoop::outer_loop_freq() const { |
| if (_child != NULL) { |
| return _child->_freq; |
| } |
| return _freq; |
| } |
| |
| #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:"); |
| 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(); |
| double prob = _exits.at(i).get_prob(); |
| tty->print(" ->%d@%d%%", blk->_pre_order, (int)(prob*100)); |
| } |
| tty->print("\n"); |
| } |
| #endif |