/* * Copyright (c) 1997, 2012, 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 "asm/macroAssembler.hpp" #include "asm/macroAssembler.inline.hpp" #include "classfile/systemDictionary.hpp" #include "code/exceptionHandlerTable.hpp" #include "code/nmethod.hpp" #include "compiler/compileLog.hpp" #include "compiler/disassembler.hpp" #include "compiler/oopMap.hpp" #include "opto/addnode.hpp" #include "opto/block.hpp" #include "opto/c2compiler.hpp" #include "opto/callGenerator.hpp" #include "opto/callnode.hpp" #include "opto/cfgnode.hpp" #include "opto/chaitin.hpp" #include "opto/compile.hpp" #include "opto/connode.hpp" #include "opto/divnode.hpp" #include "opto/escape.hpp" #include "opto/idealGraphPrinter.hpp" #include "opto/loopnode.hpp" #include "opto/machnode.hpp" #include "opto/macro.hpp" #include "opto/matcher.hpp" #include "opto/memnode.hpp" #include "opto/mulnode.hpp" #include "opto/node.hpp" #include "opto/opcodes.hpp" #include "opto/output.hpp" #include "opto/parse.hpp" #include "opto/phaseX.hpp" #include "opto/rootnode.hpp" #include "opto/runtime.hpp" #include "opto/stringopts.hpp" #include "opto/type.hpp" #include "opto/vectornode.hpp" #include "runtime/arguments.hpp" #include "runtime/signature.hpp" #include "runtime/stubRoutines.hpp" #include "runtime/timer.hpp" #include "utilities/copy.hpp" #ifdef TARGET_ARCH_MODEL_x86_32 # include "adfiles/ad_x86_32.hpp" #endif #ifdef TARGET_ARCH_MODEL_x86_64 # include "adfiles/ad_x86_64.hpp" #endif #ifdef TARGET_ARCH_MODEL_sparc # include "adfiles/ad_sparc.hpp" #endif #ifdef TARGET_ARCH_MODEL_zero # include "adfiles/ad_zero.hpp" #endif #ifdef TARGET_ARCH_MODEL_arm # include "adfiles/ad_arm.hpp" #endif #ifdef TARGET_ARCH_MODEL_ppc # include "adfiles/ad_ppc.hpp" #endif // -------------------- Compile::mach_constant_base_node ----------------------- // Constant table base node singleton. MachConstantBaseNode* Compile::mach_constant_base_node() { if (_mach_constant_base_node == NULL) { _mach_constant_base_node = new (C) MachConstantBaseNode(); _mach_constant_base_node->add_req(C->root()); } return _mach_constant_base_node; } /// Support for intrinsics. // Return the index at which m must be inserted (or already exists). // The sort order is by the address of the ciMethod, with is_virtual as minor key. int Compile::intrinsic_insertion_index(ciMethod* m, bool is_virtual) { #ifdef ASSERT for (int i = 1; i < _intrinsics->length(); i++) { CallGenerator* cg1 = _intrinsics->at(i-1); CallGenerator* cg2 = _intrinsics->at(i); assert(cg1->method() != cg2->method() ? cg1->method() < cg2->method() : cg1->is_virtual() < cg2->is_virtual(), "compiler intrinsics list must stay sorted"); } #endif // Binary search sorted list, in decreasing intervals [lo, hi]. int lo = 0, hi = _intrinsics->length()-1; while (lo <= hi) { int mid = (uint)(hi + lo) / 2; ciMethod* mid_m = _intrinsics->at(mid)->method(); if (m < mid_m) { hi = mid-1; } else if (m > mid_m) { lo = mid+1; } else { // look at minor sort key bool mid_virt = _intrinsics->at(mid)->is_virtual(); if (is_virtual < mid_virt) { hi = mid-1; } else if (is_virtual > mid_virt) { lo = mid+1; } else { return mid; // exact match } } } return lo; // inexact match } void Compile::register_intrinsic(CallGenerator* cg) { if (_intrinsics == NULL) { _intrinsics = new (comp_arena())GrowableArray(comp_arena(), 60, 0, NULL); } // This code is stolen from ciObjectFactory::insert. // Really, GrowableArray should have methods for // insert_at, remove_at, and binary_search. int len = _intrinsics->length(); int index = intrinsic_insertion_index(cg->method(), cg->is_virtual()); if (index == len) { _intrinsics->append(cg); } else { #ifdef ASSERT CallGenerator* oldcg = _intrinsics->at(index); assert(oldcg->method() != cg->method() || oldcg->is_virtual() != cg->is_virtual(), "don't register twice"); #endif _intrinsics->append(_intrinsics->at(len-1)); int pos; for (pos = len-2; pos >= index; pos--) { _intrinsics->at_put(pos+1,_intrinsics->at(pos)); } _intrinsics->at_put(index, cg); } assert(find_intrinsic(cg->method(), cg->is_virtual()) == cg, "registration worked"); } CallGenerator* Compile::find_intrinsic(ciMethod* m, bool is_virtual) { assert(m->is_loaded(), "don't try this on unloaded methods"); if (_intrinsics != NULL) { int index = intrinsic_insertion_index(m, is_virtual); if (index < _intrinsics->length() && _intrinsics->at(index)->method() == m && _intrinsics->at(index)->is_virtual() == is_virtual) { return _intrinsics->at(index); } } // Lazily create intrinsics for intrinsic IDs well-known in the runtime. if (m->intrinsic_id() != vmIntrinsics::_none && m->intrinsic_id() <= vmIntrinsics::LAST_COMPILER_INLINE) { CallGenerator* cg = make_vm_intrinsic(m, is_virtual); if (cg != NULL) { // Save it for next time: register_intrinsic(cg); return cg; } else { gather_intrinsic_statistics(m->intrinsic_id(), is_virtual, _intrinsic_disabled); } } return NULL; } // Compile:: register_library_intrinsics and make_vm_intrinsic are defined // in library_call.cpp. #ifndef PRODUCT // statistics gathering... juint Compile::_intrinsic_hist_count[vmIntrinsics::ID_LIMIT] = {0}; jubyte Compile::_intrinsic_hist_flags[vmIntrinsics::ID_LIMIT] = {0}; bool Compile::gather_intrinsic_statistics(vmIntrinsics::ID id, bool is_virtual, int flags) { assert(id > vmIntrinsics::_none && id < vmIntrinsics::ID_LIMIT, "oob"); int oflags = _intrinsic_hist_flags[id]; assert(flags != 0, "what happened?"); if (is_virtual) { flags |= _intrinsic_virtual; } bool changed = (flags != oflags); if ((flags & _intrinsic_worked) != 0) { juint count = (_intrinsic_hist_count[id] += 1); if (count == 1) { changed = true; // first time } // increment the overall count also: _intrinsic_hist_count[vmIntrinsics::_none] += 1; } if (changed) { if (((oflags ^ flags) & _intrinsic_virtual) != 0) { // Something changed about the intrinsic's virtuality. if ((flags & _intrinsic_virtual) != 0) { // This is the first use of this intrinsic as a virtual call. if (oflags != 0) { // We already saw it as a non-virtual, so note both cases. flags |= _intrinsic_both; } } else if ((oflags & _intrinsic_both) == 0) { // This is the first use of this intrinsic as a non-virtual flags |= _intrinsic_both; } } _intrinsic_hist_flags[id] = (jubyte) (oflags | flags); } // update the overall flags also: _intrinsic_hist_flags[vmIntrinsics::_none] |= (jubyte) flags; return changed; } static char* format_flags(int flags, char* buf) { buf[0] = 0; if ((flags & Compile::_intrinsic_worked) != 0) strcat(buf, ",worked"); if ((flags & Compile::_intrinsic_failed) != 0) strcat(buf, ",failed"); if ((flags & Compile::_intrinsic_disabled) != 0) strcat(buf, ",disabled"); if ((flags & Compile::_intrinsic_virtual) != 0) strcat(buf, ",virtual"); if ((flags & Compile::_intrinsic_both) != 0) strcat(buf, ",nonvirtual"); if (buf[0] == 0) strcat(buf, ","); assert(buf[0] == ',', "must be"); return &buf[1]; } void Compile::print_intrinsic_statistics() { char flagsbuf[100]; ttyLocker ttyl; if (xtty != NULL) xtty->head("statistics type='intrinsic'"); tty->print_cr("Compiler intrinsic usage:"); juint total = _intrinsic_hist_count[vmIntrinsics::_none]; if (total == 0) total = 1; // avoid div0 in case of no successes #define PRINT_STAT_LINE(name, c, f) \ tty->print_cr(" %4d (%4.1f%%) %s (%s)", (int)(c), ((c) * 100.0) / total, name, f); for (int index = 1 + (int)vmIntrinsics::_none; index < (int)vmIntrinsics::ID_LIMIT; index++) { vmIntrinsics::ID id = (vmIntrinsics::ID) index; int flags = _intrinsic_hist_flags[id]; juint count = _intrinsic_hist_count[id]; if ((flags | count) != 0) { PRINT_STAT_LINE(vmIntrinsics::name_at(id), count, format_flags(flags, flagsbuf)); } } PRINT_STAT_LINE("total", total, format_flags(_intrinsic_hist_flags[vmIntrinsics::_none], flagsbuf)); if (xtty != NULL) xtty->tail("statistics"); } void Compile::print_statistics() { { ttyLocker ttyl; if (xtty != NULL) xtty->head("statistics type='opto'"); Parse::print_statistics(); PhaseCCP::print_statistics(); PhaseRegAlloc::print_statistics(); Scheduling::print_statistics(); PhasePeephole::print_statistics(); PhaseIdealLoop::print_statistics(); if (xtty != NULL) xtty->tail("statistics"); } if (_intrinsic_hist_flags[vmIntrinsics::_none] != 0) { // put this under its own element. print_intrinsic_statistics(); } } #endif //PRODUCT // Support for bundling info Bundle* Compile::node_bundling(const Node *n) { assert(valid_bundle_info(n), "oob"); return &_node_bundling_base[n->_idx]; } bool Compile::valid_bundle_info(const Node *n) { return (_node_bundling_limit > n->_idx); } void Compile::gvn_replace_by(Node* n, Node* nn) { for (DUIterator_Last imin, i = n->last_outs(imin); i >= imin; ) { Node* use = n->last_out(i); bool is_in_table = initial_gvn()->hash_delete(use); uint uses_found = 0; for (uint j = 0; j < use->len(); j++) { if (use->in(j) == n) { if (j < use->req()) use->set_req(j, nn); else use->set_prec(j, nn); uses_found++; } } if (is_in_table) { // reinsert into table initial_gvn()->hash_find_insert(use); } record_for_igvn(use); i -= uses_found; // we deleted 1 or more copies of this edge } } static inline bool not_a_node(const Node* n) { if (n == NULL) return true; if (((intptr_t)n & 1) != 0) return true; // uninitialized, etc. if (*(address*)n == badAddress) return true; // kill by Node::destruct return false; } // Identify all nodes that are reachable from below, useful. // Use breadth-first pass that records state in a Unique_Node_List, // recursive traversal is slower. void Compile::identify_useful_nodes(Unique_Node_List &useful) { int estimated_worklist_size = unique(); useful.map( estimated_worklist_size, NULL ); // preallocate space // Initialize worklist if (root() != NULL) { useful.push(root()); } // If 'top' is cached, declare it useful to preserve cached node if( cached_top_node() ) { useful.push(cached_top_node()); } // Push all useful nodes onto the list, breadthfirst for( uint next = 0; next < useful.size(); ++next ) { assert( next < unique(), "Unique useful nodes < total nodes"); Node *n = useful.at(next); uint max = n->len(); for( uint i = 0; i < max; ++i ) { Node *m = n->in(i); if (not_a_node(m)) continue; useful.push(m); } } } // Update dead_node_list with any missing dead nodes using useful // list. Consider all non-useful nodes to be useless i.e., dead nodes. void Compile::update_dead_node_list(Unique_Node_List &useful) { uint max_idx = unique(); VectorSet& useful_node_set = useful.member_set(); for (uint node_idx = 0; node_idx < max_idx; node_idx++) { // If node with index node_idx is not in useful set, // mark it as dead in dead node list. if (! useful_node_set.test(node_idx) ) { record_dead_node(node_idx); } } } void Compile::remove_useless_late_inlines(GrowableArray* inlines, Unique_Node_List &useful) { int shift = 0; for (int i = 0; i < inlines->length(); i++) { CallGenerator* cg = inlines->at(i); CallNode* call = cg->call_node(); if (shift > 0) { inlines->at_put(i-shift, cg); } if (!useful.member(call)) { shift++; } } inlines->trunc_to(inlines->length()-shift); } // Disconnect all useless nodes by disconnecting those at the boundary. void Compile::remove_useless_nodes(Unique_Node_List &useful) { uint next = 0; while (next < useful.size()) { Node *n = useful.at(next++); // Use raw traversal of out edges since this code removes out edges int max = n->outcnt(); for (int j = 0; j < max; ++j) { Node* child = n->raw_out(j); if (! useful.member(child)) { assert(!child->is_top() || child != top(), "If top is cached in Compile object it is in useful list"); // Only need to remove this out-edge to the useless node n->raw_del_out(j); --j; --max; } } if (n->outcnt() == 1 && n->has_special_unique_user()) { record_for_igvn(n->unique_out()); } } // Remove useless macro and predicate opaq nodes for (int i = C->macro_count()-1; i >= 0; i--) { Node* n = C->macro_node(i); if (!useful.member(n)) { remove_macro_node(n); } } // Remove useless expensive node for (int i = C->expensive_count()-1; i >= 0; i--) { Node* n = C->expensive_node(i); if (!useful.member(n)) { remove_expensive_node(n); } } // clean up the late inline lists remove_useless_late_inlines(&_string_late_inlines, useful); remove_useless_late_inlines(&_late_inlines, useful); debug_only(verify_graph_edges(true/*check for no_dead_code*/);) } //------------------------------frame_size_in_words----------------------------- // frame_slots in units of words int Compile::frame_size_in_words() const { // shift is 0 in LP32 and 1 in LP64 const int shift = (LogBytesPerWord - LogBytesPerInt); int words = _frame_slots >> shift; assert( words << shift == _frame_slots, "frame size must be properly aligned in LP64" ); return words; } // ============================================================================ //------------------------------CompileWrapper--------------------------------- class CompileWrapper : public StackObj { Compile *const _compile; public: CompileWrapper(Compile* compile); ~CompileWrapper(); }; CompileWrapper::CompileWrapper(Compile* compile) : _compile(compile) { // the Compile* pointer is stored in the current ciEnv: ciEnv* env = compile->env(); assert(env == ciEnv::current(), "must already be a ciEnv active"); assert(env->compiler_data() == NULL, "compile already active?"); env->set_compiler_data(compile); assert(compile == Compile::current(), "sanity"); compile->set_type_dict(NULL); compile->set_type_hwm(NULL); compile->set_type_last_size(0); compile->set_last_tf(NULL, NULL); compile->set_indexSet_arena(NULL); compile->set_indexSet_free_block_list(NULL); compile->init_type_arena(); Type::Initialize(compile); _compile->set_scratch_buffer_blob(NULL); _compile->begin_method(); } CompileWrapper::~CompileWrapper() { _compile->end_method(); if (_compile->scratch_buffer_blob() != NULL) BufferBlob::free(_compile->scratch_buffer_blob()); _compile->env()->set_compiler_data(NULL); } //----------------------------print_compile_messages--------------------------- void Compile::print_compile_messages() { #ifndef PRODUCT // Check if recompiling if (_subsume_loads == false && PrintOpto) { // Recompiling without allowing machine instructions to subsume loads tty->print_cr("*********************************************************"); tty->print_cr("** Bailout: Recompile without subsuming loads **"); tty->print_cr("*********************************************************"); } if (_do_escape_analysis != DoEscapeAnalysis && PrintOpto) { // Recompiling without escape analysis tty->print_cr("*********************************************************"); tty->print_cr("** Bailout: Recompile without escape analysis **"); tty->print_cr("*********************************************************"); } if (env()->break_at_compile()) { // Open the debugger when compiling this method. tty->print("### Breaking when compiling: "); method()->print_short_name(); tty->cr(); BREAKPOINT; } if( PrintOpto ) { if (is_osr_compilation()) { tty->print("[OSR]%3d", _compile_id); } else { tty->print("%3d", _compile_id); } } #endif } //-----------------------init_scratch_buffer_blob------------------------------ // Construct a temporary BufferBlob and cache it for this compile. void Compile::init_scratch_buffer_blob(int const_size) { // If there is already a scratch buffer blob allocated and the // constant section is big enough, use it. Otherwise free the // current and allocate a new one. BufferBlob* blob = scratch_buffer_blob(); if ((blob != NULL) && (const_size <= _scratch_const_size)) { // Use the current blob. } else { if (blob != NULL) { BufferBlob::free(blob); } ResourceMark rm; _scratch_const_size = const_size; int size = (MAX_inst_size + MAX_stubs_size + _scratch_const_size); blob = BufferBlob::create("Compile::scratch_buffer", size); // Record the buffer blob for next time. set_scratch_buffer_blob(blob); // Have we run out of code space? if (scratch_buffer_blob() == NULL) { // Let CompilerBroker disable further compilations. record_failure("Not enough space for scratch buffer in CodeCache"); return; } } // Initialize the relocation buffers relocInfo* locs_buf = (relocInfo*) blob->content_end() - MAX_locs_size; set_scratch_locs_memory(locs_buf); } //-----------------------scratch_emit_size------------------------------------- // Helper function that computes size by emitting code uint Compile::scratch_emit_size(const Node* n) { // Start scratch_emit_size section. set_in_scratch_emit_size(true); // Emit into a trash buffer and count bytes emitted. // This is a pretty expensive way to compute a size, // but it works well enough if seldom used. // All common fixed-size instructions are given a size // method by the AD file. // Note that the scratch buffer blob and locs memory are // allocated at the beginning of the compile task, and // may be shared by several calls to scratch_emit_size. // The allocation of the scratch buffer blob is particularly // expensive, since it has to grab the code cache lock. BufferBlob* blob = this->scratch_buffer_blob(); assert(blob != NULL, "Initialize BufferBlob at start"); assert(blob->size() > MAX_inst_size, "sanity"); relocInfo* locs_buf = scratch_locs_memory(); address blob_begin = blob->content_begin(); address blob_end = (address)locs_buf; assert(blob->content_contains(blob_end), "sanity"); CodeBuffer buf(blob_begin, blob_end - blob_begin); buf.initialize_consts_size(_scratch_const_size); buf.initialize_stubs_size(MAX_stubs_size); assert(locs_buf != NULL, "sanity"); int lsize = MAX_locs_size / 3; buf.consts()->initialize_shared_locs(&locs_buf[lsize * 0], lsize); buf.insts()->initialize_shared_locs( &locs_buf[lsize * 1], lsize); buf.stubs()->initialize_shared_locs( &locs_buf[lsize * 2], lsize); // Do the emission. Label fakeL; // Fake label for branch instructions. Label* saveL = NULL; uint save_bnum = 0; bool is_branch = n->is_MachBranch(); if (is_branch) { MacroAssembler masm(&buf); masm.bind(fakeL); n->as_MachBranch()->save_label(&saveL, &save_bnum); n->as_MachBranch()->label_set(&fakeL, 0); } n->emit(buf, this->regalloc()); if (is_branch) // Restore label. n->as_MachBranch()->label_set(saveL, save_bnum); // End scratch_emit_size section. set_in_scratch_emit_size(false); return buf.insts_size(); } // ============================================================================ //------------------------------Compile standard------------------------------- debug_only( int Compile::_debug_idx = 100000; ) // Compile a method. entry_bci is -1 for normal compilations and indicates // the continuation bci for on stack replacement. Compile::Compile( ciEnv* ci_env, C2Compiler* compiler, ciMethod* target, int osr_bci, bool subsume_loads, bool do_escape_analysis ) : Phase(Compiler), _env(ci_env), _log(ci_env->log()), _compile_id(ci_env->compile_id()), _save_argument_registers(false), _stub_name(NULL), _stub_function(NULL), _stub_entry_point(NULL), _method(target), _entry_bci(osr_bci), _initial_gvn(NULL), _for_igvn(NULL), _warm_calls(NULL), _subsume_loads(subsume_loads), _do_escape_analysis(do_escape_analysis), _failure_reason(NULL), _code_buffer("Compile::Fill_buffer"), _orig_pc_slot(0), _orig_pc_slot_offset_in_bytes(0), _has_method_handle_invokes(false), _mach_constant_base_node(NULL), _node_bundling_limit(0), _node_bundling_base(NULL), _java_calls(0), _inner_loops(0), _scratch_const_size(-1), _in_scratch_emit_size(false), _dead_node_list(comp_arena()), _dead_node_count(0), #ifndef PRODUCT _trace_opto_output(TraceOptoOutput || method()->has_option("TraceOptoOutput")), _printer(IdealGraphPrinter::printer()), #endif _congraph(NULL), _late_inlines(comp_arena(), 2, 0, NULL), _string_late_inlines(comp_arena(), 2, 0, NULL), _late_inlines_pos(0), _number_of_mh_late_inlines(0), _inlining_progress(false), _inlining_incrementally(false), _print_inlining_list(NULL), _print_inlining(0) { C = this; CompileWrapper cw(this); #ifndef PRODUCT if (TimeCompiler2) { tty->print(" "); target->holder()->name()->print(); tty->print("."); target->print_short_name(); tty->print(" "); } TraceTime t1("Total compilation time", &_t_totalCompilation, TimeCompiler, TimeCompiler2); TraceTime t2(NULL, &_t_methodCompilation, TimeCompiler, false); bool print_opto_assembly = PrintOptoAssembly || _method->has_option("PrintOptoAssembly"); if (!print_opto_assembly) { bool print_assembly = (PrintAssembly || _method->should_print_assembly()); if (print_assembly && !Disassembler::can_decode()) { tty->print_cr("PrintAssembly request changed to PrintOptoAssembly"); print_opto_assembly = true; } } set_print_assembly(print_opto_assembly); set_parsed_irreducible_loop(false); #endif if (ProfileTraps) { // Make sure the method being compiled gets its own MDO, // so we can at least track the decompile_count(). method()->ensure_method_data(); } Init(::AliasLevel); print_compile_messages(); if (UseOldInlining || PrintCompilation NOT_PRODUCT( || PrintOpto) ) _ilt = InlineTree::build_inline_tree_root(); else _ilt = NULL; // Even if NO memory addresses are used, MergeMem nodes must have at least 1 slice assert(num_alias_types() >= AliasIdxRaw, ""); #define MINIMUM_NODE_HASH 1023 // Node list that Iterative GVN will start with Unique_Node_List for_igvn(comp_arena()); set_for_igvn(&for_igvn); // GVN that will be run immediately on new nodes uint estimated_size = method()->code_size()*4+64; estimated_size = (estimated_size < MINIMUM_NODE_HASH ? MINIMUM_NODE_HASH : estimated_size); PhaseGVN gvn(node_arena(), estimated_size); set_initial_gvn(&gvn); if (PrintInlining || PrintIntrinsics NOT_PRODUCT( || PrintOptoInlining)) { _print_inlining_list = new (comp_arena())GrowableArray(comp_arena(), 1, 1, PrintInliningBuffer()); } { // Scope for timing the parser TracePhase t3("parse", &_t_parser, true); // Put top into the hash table ASAP. initial_gvn()->transform_no_reclaim(top()); // Set up tf(), start(), and find a CallGenerator. CallGenerator* cg = NULL; if (is_osr_compilation()) { const TypeTuple *domain = StartOSRNode::osr_domain(); const TypeTuple *range = TypeTuple::make_range(method()->signature()); init_tf(TypeFunc::make(domain, range)); StartNode* s = new (this) StartOSRNode(root(), domain); initial_gvn()->set_type_bottom(s); init_start(s); cg = CallGenerator::for_osr(method(), entry_bci()); } else { // Normal case. init_tf(TypeFunc::make(method())); StartNode* s = new (this) StartNode(root(), tf()->domain()); initial_gvn()->set_type_bottom(s); init_start(s); if (method()->intrinsic_id() == vmIntrinsics::_Reference_get && UseG1GC) { // With java.lang.ref.reference.get() we must go through the // intrinsic when G1 is enabled - even when get() is the root // method of the compile - so that, if necessary, the value in // the referent field of the reference object gets recorded by // the pre-barrier code. // Specifically, if G1 is enabled, the value in the referent // field is recorded by the G1 SATB pre barrier. This will // result in the referent being marked live and the reference // object removed from the list of discovered references during // reference processing. cg = find_intrinsic(method(), false); } if (cg == NULL) { float past_uses = method()->interpreter_invocation_count(); float expected_uses = past_uses; cg = CallGenerator::for_inline(method(), expected_uses); } } if (failing()) return; if (cg == NULL) { record_method_not_compilable_all_tiers("cannot parse method"); return; } JVMState* jvms = build_start_state(start(), tf()); if ((jvms = cg->generate(jvms)) == NULL) { record_method_not_compilable("method parse failed"); return; } GraphKit kit(jvms); if (!kit.stopped()) { // Accept return values, and transfer control we know not where. // This is done by a special, unique ReturnNode bound to root. return_values(kit.jvms()); } if (kit.has_exceptions()) { // Any exceptions that escape from this call must be rethrown // to whatever caller is dynamically above us on the stack. // This is done by a special, unique RethrowNode bound to root. rethrow_exceptions(kit.transfer_exceptions_into_jvms()); } assert(IncrementalInline || (_late_inlines.length() == 0 && !has_mh_late_inlines()), "incremental inlining is off"); if (_late_inlines.length() == 0 && !has_mh_late_inlines() && !failing() && has_stringbuilder()) { inline_string_calls(true); } if (failing()) return; print_method("Before RemoveUseless", 3); // Remove clutter produced by parsing. if (!failing()) { ResourceMark rm; PhaseRemoveUseless pru(initial_gvn(), &for_igvn); } } // Note: Large methods are capped off in do_one_bytecode(). if (failing()) return; // After parsing, node notes are no longer automagic. // They must be propagated by register_new_node_with_optimizer(), // clone(), or the like. set_default_node_notes(NULL); for (;;) { int successes = Inline_Warm(); if (failing()) return; if (successes == 0) break; } // Drain the list. Finish_Warm(); #ifndef PRODUCT if (_printer) { _printer->print_inlining(this); } #endif if (failing()) return; NOT_PRODUCT( verify_graph_edges(); ) // Now optimize Optimize(); if (failing()) return; NOT_PRODUCT( verify_graph_edges(); ) #ifndef PRODUCT if (PrintIdeal) { ttyLocker ttyl; // keep the following output all in one block // This output goes directly to the tty, not the compiler log. // To enable tools to match it up with the compilation activity, // be sure to tag this tty output with the compile ID. if (xtty != NULL) { xtty->head("ideal compile_id='%d'%s", compile_id(), is_osr_compilation() ? " compile_kind='osr'" : ""); } root()->dump(9999); if (xtty != NULL) { xtty->tail("ideal"); } } #endif // Now that we know the size of all the monitors we can add a fixed slot // for the original deopt pc. _orig_pc_slot = fixed_slots(); int next_slot = _orig_pc_slot + (sizeof(address) / VMRegImpl::stack_slot_size); set_fixed_slots(next_slot); // Now generate code Code_Gen(); if (failing()) return; // Check if we want to skip execution of all compiled code. { #ifndef PRODUCT if (OptoNoExecute) { record_method_not_compilable("+OptoNoExecute"); // Flag as failed return; } TracePhase t2("install_code", &_t_registerMethod, TimeCompiler); #endif if (is_osr_compilation()) { _code_offsets.set_value(CodeOffsets::Verified_Entry, 0); _code_offsets.set_value(CodeOffsets::OSR_Entry, _first_block_size); } else { _code_offsets.set_value(CodeOffsets::Verified_Entry, _first_block_size); _code_offsets.set_value(CodeOffsets::OSR_Entry, 0); } env()->register_method(_method, _entry_bci, &_code_offsets, _orig_pc_slot_offset_in_bytes, code_buffer(), frame_size_in_words(), _oop_map_set, &_handler_table, &_inc_table, compiler, env()->comp_level(), has_unsafe_access(), SharedRuntime::is_wide_vector(max_vector_size()) ); if (log() != NULL) // Print code cache state into compiler log log()->code_cache_state(); } } //------------------------------Compile---------------------------------------- // Compile a runtime stub Compile::Compile( ciEnv* ci_env, TypeFunc_generator generator, address stub_function, const char *stub_name, int is_fancy_jump, bool pass_tls, bool save_arg_registers, bool return_pc ) : Phase(Compiler), _env(ci_env), _log(ci_env->log()), _compile_id(-1), _save_argument_registers(save_arg_registers), _method(NULL), _stub_name(stub_name), _stub_function(stub_function), _stub_entry_point(NULL), _entry_bci(InvocationEntryBci), _initial_gvn(NULL), _for_igvn(NULL), _warm_calls(NULL), _orig_pc_slot(0), _orig_pc_slot_offset_in_bytes(0), _subsume_loads(true), _do_escape_analysis(false), _failure_reason(NULL), _code_buffer("Compile::Fill_buffer"), _has_method_handle_invokes(false), _mach_constant_base_node(NULL), _node_bundling_limit(0), _node_bundling_base(NULL), _java_calls(0), _inner_loops(0), #ifndef PRODUCT _trace_opto_output(TraceOptoOutput), _printer(NULL), #endif _dead_node_list(comp_arena()), _dead_node_count(0), _congraph(NULL), _number_of_mh_late_inlines(0), _inlining_progress(false), _inlining_incrementally(false), _print_inlining_list(NULL), _print_inlining(0) { C = this; #ifndef PRODUCT TraceTime t1(NULL, &_t_totalCompilation, TimeCompiler, false); TraceTime t2(NULL, &_t_stubCompilation, TimeCompiler, false); set_print_assembly(PrintFrameConverterAssembly); set_parsed_irreducible_loop(false); #endif CompileWrapper cw(this); Init(/*AliasLevel=*/ 0); init_tf((*generator)()); { // The following is a dummy for the sake of GraphKit::gen_stub Unique_Node_List for_igvn(comp_arena()); set_for_igvn(&for_igvn); // not used, but some GraphKit guys push on this PhaseGVN gvn(Thread::current()->resource_area(),255); set_initial_gvn(&gvn); // not significant, but GraphKit guys use it pervasively gvn.transform_no_reclaim(top()); GraphKit kit; kit.gen_stub(stub_function, stub_name, is_fancy_jump, pass_tls, return_pc); } NOT_PRODUCT( verify_graph_edges(); ) Code_Gen(); if (failing()) return; // Entry point will be accessed using compile->stub_entry_point(); if (code_buffer() == NULL) { Matcher::soft_match_failure(); } else { if (PrintAssembly && (WizardMode || Verbose)) tty->print_cr("### Stub::%s", stub_name); if (!failing()) { assert(_fixed_slots == 0, "no fixed slots used for runtime stubs"); // Make the NMethod // For now we mark the frame as never safe for profile stackwalking RuntimeStub *rs = RuntimeStub::new_runtime_stub(stub_name, code_buffer(), CodeOffsets::frame_never_safe, // _code_offsets.value(CodeOffsets::Frame_Complete), frame_size_in_words(), _oop_map_set, save_arg_registers); assert(rs != NULL && rs->is_runtime_stub(), "sanity check"); _stub_entry_point = rs->entry_point(); } } } //------------------------------Init------------------------------------------- // Prepare for a single compilation void Compile::Init(int aliaslevel) { _unique = 0; _regalloc = NULL; _tf = NULL; // filled in later _top = NULL; // cached later _matcher = NULL; // filled in later _cfg = NULL; // filled in later set_24_bit_selection_and_mode(Use24BitFP, false); _node_note_array = NULL; _default_node_notes = NULL; _immutable_memory = NULL; // filled in at first inquiry // Globally visible Nodes // First set TOP to NULL to give safe behavior during creation of RootNode set_cached_top_node(NULL); set_root(new (this) RootNode()); // Now that you have a Root to point to, create the real TOP set_cached_top_node( new (this) ConNode(Type::TOP) ); set_recent_alloc(NULL, NULL); // Create Debug Information Recorder to record scopes, oopmaps, etc. env()->set_oop_recorder(new OopRecorder(env()->arena())); env()->set_debug_info(new DebugInformationRecorder(env()->oop_recorder())); env()->set_dependencies(new Dependencies(env())); _fixed_slots = 0; set_has_split_ifs(false); set_has_loops(has_method() && method()->has_loops()); // first approximation set_has_stringbuilder(false); _trap_can_recompile = false; // no traps emitted yet _major_progress = true; // start out assuming good things will happen set_has_unsafe_access(false); set_max_vector_size(0); Copy::zero_to_bytes(_trap_hist, sizeof(_trap_hist)); set_decompile_count(0); set_do_freq_based_layout(BlockLayoutByFrequency || method_has_option("BlockLayoutByFrequency")); set_num_loop_opts(LoopOptsCount); set_do_inlining(Inline); set_max_inline_size(MaxInlineSize); set_freq_inline_size(FreqInlineSize); set_do_scheduling(OptoScheduling); set_do_count_invocations(false); set_do_method_data_update(false); if (debug_info()->recording_non_safepoints()) { set_node_note_array(new(comp_arena()) GrowableArray (comp_arena(), 8, 0, NULL)); set_default_node_notes(Node_Notes::make(this)); } // // -- Initialize types before each compile -- // // Update cached type information // if( _method && _method->constants() ) // Type::update_loaded_types(_method, _method->constants()); // Init alias_type map. if (!_do_escape_analysis && aliaslevel == 3) aliaslevel = 2; // No unique types without escape analysis _AliasLevel = aliaslevel; const int grow_ats = 16; _max_alias_types = grow_ats; _alias_types = NEW_ARENA_ARRAY(comp_arena(), AliasType*, grow_ats); AliasType* ats = NEW_ARENA_ARRAY(comp_arena(), AliasType, grow_ats); Copy::zero_to_bytes(ats, sizeof(AliasType)*grow_ats); { for (int i = 0; i < grow_ats; i++) _alias_types[i] = &ats[i]; } // Initialize the first few types. _alias_types[AliasIdxTop]->Init(AliasIdxTop, NULL); _alias_types[AliasIdxBot]->Init(AliasIdxBot, TypePtr::BOTTOM); _alias_types[AliasIdxRaw]->Init(AliasIdxRaw, TypeRawPtr::BOTTOM); _num_alias_types = AliasIdxRaw+1; // Zero out the alias type cache. Copy::zero_to_bytes(_alias_cache, sizeof(_alias_cache)); // A NULL adr_type hits in the cache right away. Preload the right answer. probe_alias_cache(NULL)->_index = AliasIdxTop; _intrinsics = NULL; _macro_nodes = new(comp_arena()) GrowableArray(comp_arena(), 8, 0, NULL); _predicate_opaqs = new(comp_arena()) GrowableArray(comp_arena(), 8, 0, NULL); _expensive_nodes = new(comp_arena()) GrowableArray(comp_arena(), 8, 0, NULL); register_library_intrinsics(); } //---------------------------init_start---------------------------------------- // Install the StartNode on this compile object. void Compile::init_start(StartNode* s) { if (failing()) return; // already failing assert(s == start(), ""); } StartNode* Compile::start() const { assert(!failing(), ""); for (DUIterator_Fast imax, i = root()->fast_outs(imax); i < imax; i++) { Node* start = root()->fast_out(i); if( start->is_Start() ) return start->as_Start(); } ShouldNotReachHere(); return NULL; } //-------------------------------immutable_memory------------------------------------- // Access immutable memory Node* Compile::immutable_memory() { if (_immutable_memory != NULL) { return _immutable_memory; } StartNode* s = start(); for (DUIterator_Fast imax, i = s->fast_outs(imax); true; i++) { Node *p = s->fast_out(i); if (p != s && p->as_Proj()->_con == TypeFunc::Memory) { _immutable_memory = p; return _immutable_memory; } } ShouldNotReachHere(); return NULL; } //----------------------set_cached_top_node------------------------------------ // Install the cached top node, and make sure Node::is_top works correctly. void Compile::set_cached_top_node(Node* tn) { if (tn != NULL) verify_top(tn); Node* old_top = _top; _top = tn; // Calling Node::setup_is_top allows the nodes the chance to adjust // their _out arrays. if (_top != NULL) _top->setup_is_top(); if (old_top != NULL) old_top->setup_is_top(); assert(_top == NULL || top()->is_top(), ""); } #ifdef ASSERT uint Compile::count_live_nodes_by_graph_walk() { Unique_Node_List useful(comp_arena()); // Get useful node list by walking the graph. identify_useful_nodes(useful); return useful.size(); } void Compile::print_missing_nodes() { // Return if CompileLog is NULL and PrintIdealNodeCount is false. if ((_log == NULL) && (! PrintIdealNodeCount)) { return; } // This is an expensive function. It is executed only when the user // specifies VerifyIdealNodeCount option or otherwise knows the // additional work that needs to be done to identify reachable nodes // by walking the flow graph and find the missing ones using // _dead_node_list. Unique_Node_List useful(comp_arena()); // Get useful node list by walking the graph. identify_useful_nodes(useful); uint l_nodes = C->live_nodes(); uint l_nodes_by_walk = useful.size(); if (l_nodes != l_nodes_by_walk) { if (_log != NULL) { _log->begin_head("mismatched_nodes count='%d'", abs((int) (l_nodes - l_nodes_by_walk))); _log->stamp(); _log->end_head(); } VectorSet& useful_member_set = useful.member_set(); int last_idx = l_nodes_by_walk; for (int i = 0; i < last_idx; i++) { if (useful_member_set.test(i)) { if (_dead_node_list.test(i)) { if (_log != NULL) { _log->elem("mismatched_node_info node_idx='%d' type='both live and dead'", i); } if (PrintIdealNodeCount) { // Print the log message to tty tty->print_cr("mismatched_node idx='%d' both live and dead'", i); useful.at(i)->dump(); } } } else if (! _dead_node_list.test(i)) { if (_log != NULL) { _log->elem("mismatched_node_info node_idx='%d' type='neither live nor dead'", i); } if (PrintIdealNodeCount) { // Print the log message to tty tty->print_cr("mismatched_node idx='%d' type='neither live nor dead'", i); } } } if (_log != NULL) { _log->tail("mismatched_nodes"); } } } #endif #ifndef PRODUCT void Compile::verify_top(Node* tn) const { if (tn != NULL) { assert(tn->is_Con(), "top node must be a constant"); assert(((ConNode*)tn)->type() == Type::TOP, "top node must have correct type"); assert(tn->in(0) != NULL, "must have live top node"); } } #endif ///-------------------Managing Per-Node Debug & Profile Info------------------- void Compile::grow_node_notes(GrowableArray* arr, int grow_by) { guarantee(arr != NULL, ""); int num_blocks = arr->length(); if (grow_by < num_blocks) grow_by = num_blocks; int num_notes = grow_by * _node_notes_block_size; Node_Notes* notes = NEW_ARENA_ARRAY(node_arena(), Node_Notes, num_notes); Copy::zero_to_bytes(notes, num_notes * sizeof(Node_Notes)); while (num_notes > 0) { arr->append(notes); notes += _node_notes_block_size; num_notes -= _node_notes_block_size; } assert(num_notes == 0, "exact multiple, please"); } bool Compile::copy_node_notes_to(Node* dest, Node* source) { if (source == NULL || dest == NULL) return false; if (dest->is_Con()) return false; // Do not push debug info onto constants. #ifdef ASSERT // Leave a bread crumb trail pointing to the original node: if (dest != NULL && dest != source && dest->debug_orig() == NULL) { dest->set_debug_orig(source); } #endif if (node_note_array() == NULL) return false; // Not collecting any notes now. // This is a copy onto a pre-existing node, which may already have notes. // If both nodes have notes, do not overwrite any pre-existing notes. Node_Notes* source_notes = node_notes_at(source->_idx); if (source_notes == NULL || source_notes->is_clear()) return false; Node_Notes* dest_notes = node_notes_at(dest->_idx); if (dest_notes == NULL || dest_notes->is_clear()) { return set_node_notes_at(dest->_idx, source_notes); } Node_Notes merged_notes = (*source_notes); // The order of operations here ensures that dest notes will win... merged_notes.update_from(dest_notes); return set_node_notes_at(dest->_idx, &merged_notes); } //--------------------------allow_range_check_smearing------------------------- // Gating condition for coalescing similar range checks. // Sometimes we try 'speculatively' replacing a series of a range checks by a // single covering check that is at least as strong as any of them. // If the optimization succeeds, the simplified (strengthened) range check // will always succeed. If it fails, we will deopt, and then give up // on the optimization. bool Compile::allow_range_check_smearing() const { // If this method has already thrown a range-check, // assume it was because we already tried range smearing // and it failed. uint already_trapped = trap_count(Deoptimization::Reason_range_check); return !already_trapped; } //------------------------------flatten_alias_type----------------------------- const TypePtr *Compile::flatten_alias_type( const TypePtr *tj ) const { int offset = tj->offset(); TypePtr::PTR ptr = tj->ptr(); // Known instance (scalarizable allocation) alias only with itself. bool is_known_inst = tj->isa_oopptr() != NULL && tj->is_oopptr()->is_known_instance(); // Process weird unsafe references. if (offset == Type::OffsetBot && (tj->isa_instptr() /*|| tj->isa_klassptr()*/)) { assert(InlineUnsafeOps, "indeterminate pointers come only from unsafe ops"); assert(!is_known_inst, "scalarizable allocation should not have unsafe references"); tj = TypeOopPtr::BOTTOM; ptr = tj->ptr(); offset = tj->offset(); } // Array pointers need some flattening const TypeAryPtr *ta = tj->isa_aryptr(); if( ta && is_known_inst ) { if ( offset != Type::OffsetBot && offset > arrayOopDesc::length_offset_in_bytes() ) { offset = Type::OffsetBot; // Flatten constant access into array body only tj = ta = TypeAryPtr::make(ptr, ta->ary(), ta->klass(), true, offset, ta->instance_id()); } } else if( ta && _AliasLevel >= 2 ) { // For arrays indexed by constant indices, we flatten the alias // space to include all of the array body. Only the header, klass // and array length can be accessed un-aliased. if( offset != Type::OffsetBot ) { if( ta->const_oop() ) { // MethodData* or Method* offset = Type::OffsetBot; // Flatten constant access into array body tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),ta->ary(),ta->klass(),false,offset); } else if( offset == arrayOopDesc::length_offset_in_bytes() ) { // range is OK as-is. tj = ta = TypeAryPtr::RANGE; } else if( offset == oopDesc::klass_offset_in_bytes() ) { tj = TypeInstPtr::KLASS; // all klass loads look alike ta = TypeAryPtr::RANGE; // generic ignored junk ptr = TypePtr::BotPTR; } else if( offset == oopDesc::mark_offset_in_bytes() ) { tj = TypeInstPtr::MARK; ta = TypeAryPtr::RANGE; // generic ignored junk ptr = TypePtr::BotPTR; } else { // Random constant offset into array body offset = Type::OffsetBot; // Flatten constant access into array body tj = ta = TypeAryPtr::make(ptr,ta->ary(),ta->klass(),false,offset); } } // Arrays of fixed size alias with arrays of unknown size. if (ta->size() != TypeInt::POS) { const TypeAry *tary = TypeAry::make(ta->elem(), TypeInt::POS); tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),tary,ta->klass(),false,offset); } // Arrays of known objects become arrays of unknown objects. if (ta->elem()->isa_narrowoop() && ta->elem() != TypeNarrowOop::BOTTOM) { const TypeAry *tary = TypeAry::make(TypeNarrowOop::BOTTOM, ta->size()); tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),tary,NULL,false,offset); } if (ta->elem()->isa_oopptr() && ta->elem() != TypeInstPtr::BOTTOM) { const TypeAry *tary = TypeAry::make(TypeInstPtr::BOTTOM, ta->size()); tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),tary,NULL,false,offset); } // Arrays of bytes and of booleans both use 'bastore' and 'baload' so // cannot be distinguished by bytecode alone. if (ta->elem() == TypeInt::BOOL) { const TypeAry *tary = TypeAry::make(TypeInt::BYTE, ta->size()); ciKlass* aklass = ciTypeArrayKlass::make(T_BYTE); tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),tary,aklass,false,offset); } // During the 2nd round of IterGVN, NotNull castings are removed. // Make sure the Bottom and NotNull variants alias the same. // Also, make sure exact and non-exact variants alias the same. if( ptr == TypePtr::NotNull || ta->klass_is_exact() ) { tj = ta = TypeAryPtr::make(TypePtr::BotPTR,ta->ary(),ta->klass(),false,offset); } } // Oop pointers need some flattening const TypeInstPtr *to = tj->isa_instptr(); if( to && _AliasLevel >= 2 && to != TypeOopPtr::BOTTOM ) { ciInstanceKlass *k = to->klass()->as_instance_klass(); if( ptr == TypePtr::Constant ) { if (to->klass() != ciEnv::current()->Class_klass() || offset < k->size_helper() * wordSize) { // No constant oop pointers (such as Strings); they alias with // unknown strings. assert(!is_known_inst, "not scalarizable allocation"); tj = to = TypeInstPtr::make(TypePtr::BotPTR,to->klass(),false,0,offset); } } else if( is_known_inst ) { tj = to; // Keep NotNull and klass_is_exact for instance type } else if( ptr == TypePtr::NotNull || to->klass_is_exact() ) { // During the 2nd round of IterGVN, NotNull castings are removed. // Make sure the Bottom and NotNull variants alias the same. // Also, make sure exact and non-exact variants alias the same. tj = to = TypeInstPtr::make(TypePtr::BotPTR,to->klass(),false,0,offset); } // Canonicalize the holder of this field if (offset >= 0 && offset < instanceOopDesc::base_offset_in_bytes()) { // First handle header references such as a LoadKlassNode, even if the // object's klass is unloaded at compile time (4965979). if (!is_known_inst) { // Do it only for non-instance types tj = to = TypeInstPtr::make(TypePtr::BotPTR, env()->Object_klass(), false, NULL, offset); } } else if (offset < 0 || offset >= k->size_helper() * wordSize) { // Static fields are in the space above the normal instance // fields in the java.lang.Class instance. if (to->klass() != ciEnv::current()->Class_klass()) { to = NULL; tj = TypeOopPtr::BOTTOM; offset = tj->offset(); } } else { ciInstanceKlass *canonical_holder = k->get_canonical_holder(offset); if (!k->equals(canonical_holder) || tj->offset() != offset) { if( is_known_inst ) { tj = to = TypeInstPtr::make(to->ptr(), canonical_holder, true, NULL, offset, to->instance_id()); } else { tj = to = TypeInstPtr::make(to->ptr(), canonical_holder, false, NULL, offset); } } } } // Klass pointers to object array klasses need some flattening const TypeKlassPtr *tk = tj->isa_klassptr(); if( tk ) { // If we are referencing a field within a Klass, we need // to assume the worst case of an Object. Both exact and // inexact types must flatten to the same alias class so // use NotNull as the PTR. if ( offset == Type::OffsetBot || (offset >= 0 && (size_t)offset < sizeof(Klass)) ) { tj = tk = TypeKlassPtr::make(TypePtr::NotNull, TypeKlassPtr::OBJECT->klass(), offset); } ciKlass* klass = tk->klass(); if( klass->is_obj_array_klass() ) { ciKlass* k = TypeAryPtr::OOPS->klass(); if( !k || !k->is_loaded() ) // Only fails for some -Xcomp runs k = TypeInstPtr::BOTTOM->klass(); tj = tk = TypeKlassPtr::make( TypePtr::NotNull, k, offset ); } // Check for precise loads from the primary supertype array and force them // to the supertype cache alias index. Check for generic array loads from // the primary supertype array and also force them to the supertype cache // alias index. Since the same load can reach both, we need to merge // these 2 disparate memories into the same alias class. Since the // primary supertype array is read-only, there's no chance of confusion // where we bypass an array load and an array store. int primary_supers_offset = in_bytes(Klass::primary_supers_offset()); if (offset == Type::OffsetBot || (offset >= primary_supers_offset && offset < (int)(primary_supers_offset + Klass::primary_super_limit() * wordSize)) || offset == (int)in_bytes(Klass::secondary_super_cache_offset())) { offset = in_bytes(Klass::secondary_super_cache_offset()); tj = tk = TypeKlassPtr::make( TypePtr::NotNull, tk->klass(), offset ); } } // Flatten all Raw pointers together. if (tj->base() == Type::RawPtr) tj = TypeRawPtr::BOTTOM; if (tj->base() == Type::AnyPtr) tj = TypePtr::BOTTOM; // An error, which the caller must check for. // Flatten all to bottom for now switch( _AliasLevel ) { case 0: tj = TypePtr::BOTTOM; break; case 1: // Flatten to: oop, static, field or array switch (tj->base()) { //case Type::AryPtr: tj = TypeAryPtr::RANGE; break; case Type::RawPtr: tj = TypeRawPtr::BOTTOM; break; case Type::AryPtr: // do not distinguish arrays at all case Type::InstPtr: tj = TypeInstPtr::BOTTOM; break; case Type::KlassPtr: tj = TypeKlassPtr::OBJECT; break; case Type::AnyPtr: tj = TypePtr::BOTTOM; break; // caller checks it default: ShouldNotReachHere(); } break; case 2: // No collapsing at level 2; keep all splits case 3: // No collapsing at level 3; keep all splits break; default: Unimplemented(); } offset = tj->offset(); assert( offset != Type::OffsetTop, "Offset has fallen from constant" ); assert( (offset != Type::OffsetBot && tj->base() != Type::AryPtr) || (offset == Type::OffsetBot && tj->base() == Type::AryPtr) || (offset == Type::OffsetBot && tj == TypeOopPtr::BOTTOM) || (offset == Type::OffsetBot && tj == TypePtr::BOTTOM) || (offset == oopDesc::mark_offset_in_bytes() && tj->base() == Type::AryPtr) || (offset == oopDesc::klass_offset_in_bytes() && tj->base() == Type::AryPtr) || (offset == arrayOopDesc::length_offset_in_bytes() && tj->base() == Type::AryPtr) , "For oops, klasses, raw offset must be constant; for arrays the offset is never known" ); assert( tj->ptr() != TypePtr::TopPTR && tj->ptr() != TypePtr::AnyNull && tj->ptr() != TypePtr::Null, "No imprecise addresses" ); // assert( tj->ptr() != TypePtr::Constant || // tj->base() == Type::RawPtr || // tj->base() == Type::KlassPtr, "No constant oop addresses" ); return tj; } void Compile::AliasType::Init(int i, const TypePtr* at) { _index = i; _adr_type = at; _field = NULL; _is_rewritable = true; // default const TypeOopPtr *atoop = (at != NULL) ? at->isa_oopptr() : NULL; if (atoop != NULL && atoop->is_known_instance()) { const TypeOopPtr *gt = atoop->cast_to_instance_id(TypeOopPtr::InstanceBot); _general_index = Compile::current()->get_alias_index(gt); } else { _general_index = 0; } } //---------------------------------print_on------------------------------------ #ifndef PRODUCT void Compile::AliasType::print_on(outputStream* st) { if (index() < 10) st->print("@ <%d> ", index()); else st->print("@ <%d>", index()); st->print(is_rewritable() ? " " : " RO"); int offset = adr_type()->offset(); if (offset == Type::OffsetBot) st->print(" +any"); else st->print(" +%-3d", offset); st->print(" in "); adr_type()->dump_on(st); const TypeOopPtr* tjp = adr_type()->isa_oopptr(); if (field() != NULL && tjp) { if (tjp->klass() != field()->holder() || tjp->offset() != field()->offset_in_bytes()) { st->print(" != "); field()->print(); st->print(" ***"); } } } void print_alias_types() { Compile* C = Compile::current(); tty->print_cr("--- Alias types, AliasIdxBot .. %d", C->num_alias_types()-1); for (int idx = Compile::AliasIdxBot; idx < C->num_alias_types(); idx++) { C->alias_type(idx)->print_on(tty); tty->cr(); } } #endif //----------------------------probe_alias_cache-------------------------------- Compile::AliasCacheEntry* Compile::probe_alias_cache(const TypePtr* adr_type) { intptr_t key = (intptr_t) adr_type; key ^= key >> logAliasCacheSize; return &_alias_cache[key & right_n_bits(logAliasCacheSize)]; } //-----------------------------grow_alias_types-------------------------------- void Compile::grow_alias_types() { const int old_ats = _max_alias_types; // how many before? const int new_ats = old_ats; // how many more? const int grow_ats = old_ats+new_ats; // how many now? _max_alias_types = grow_ats; _alias_types = REALLOC_ARENA_ARRAY(comp_arena(), AliasType*, _alias_types, old_ats, grow_ats); AliasType* ats = NEW_ARENA_ARRAY(comp_arena(), AliasType, new_ats); Copy::zero_to_bytes(ats, sizeof(AliasType)*new_ats); for (int i = 0; i < new_ats; i++) _alias_types[old_ats+i] = &ats[i]; } //--------------------------------find_alias_type------------------------------ Compile::AliasType* Compile::find_alias_type(const TypePtr* adr_type, bool no_create, ciField* original_field) { if (_AliasLevel == 0) return alias_type(AliasIdxBot); AliasCacheEntry* ace = probe_alias_cache(adr_type); if (ace->_adr_type == adr_type) { return alias_type(ace->_index); } // Handle special cases. if (adr_type == NULL) return alias_type(AliasIdxTop); if (adr_type == TypePtr::BOTTOM) return alias_type(AliasIdxBot); // Do it the slow way. const TypePtr* flat = flatten_alias_type(adr_type); #ifdef ASSERT assert(flat == flatten_alias_type(flat), "idempotent"); assert(flat != TypePtr::BOTTOM, "cannot alias-analyze an untyped ptr"); if (flat->isa_oopptr() && !flat->isa_klassptr()) { const TypeOopPtr* foop = flat->is_oopptr(); // Scalarizable allocations have exact klass always. bool exact = !foop->klass_is_exact() || foop->is_known_instance(); const TypePtr* xoop = foop->cast_to_exactness(exact)->is_ptr(); assert(foop == flatten_alias_type(xoop), "exactness must not affect alias type"); } assert(flat == flatten_alias_type(flat), "exact bit doesn't matter"); #endif int idx = AliasIdxTop; for (int i = 0; i < num_alias_types(); i++) { if (alias_type(i)->adr_type() == flat) { idx = i; break; } } if (idx == AliasIdxTop) { if (no_create) return NULL; // Grow the array if necessary. if (_num_alias_types == _max_alias_types) grow_alias_types(); // Add a new alias type. idx = _num_alias_types++; _alias_types[idx]->Init(idx, flat); if (flat == TypeInstPtr::KLASS) alias_type(idx)->set_rewritable(false); if (flat == TypeAryPtr::RANGE) alias_type(idx)->set_rewritable(false); if (flat->isa_instptr()) { if (flat->offset() == java_lang_Class::klass_offset_in_bytes() && flat->is_instptr()->klass() == env()->Class_klass()) alias_type(idx)->set_rewritable(false); } if (flat->isa_klassptr()) { if (flat->offset() == in_bytes(Klass::super_check_offset_offset())) alias_type(idx)->set_rewritable(false); if (flat->offset() == in_bytes(Klass::modifier_flags_offset())) alias_type(idx)->set_rewritable(false); if (flat->offset() == in_bytes(Klass::access_flags_offset())) alias_type(idx)->set_rewritable(false); if (flat->offset() == in_bytes(Klass::java_mirror_offset())) alias_type(idx)->set_rewritable(false); } // %%% (We would like to finalize JavaThread::threadObj_offset(), // but the base pointer type is not distinctive enough to identify // references into JavaThread.) // Check for final fields. const TypeInstPtr* tinst = flat->isa_instptr(); if (tinst && tinst->offset() >= instanceOopDesc::base_offset_in_bytes()) { ciField* field; if (tinst->const_oop() != NULL && tinst->klass() == ciEnv::current()->Class_klass() && tinst->offset() >= (tinst->klass()->as_instance_klass()->size_helper() * wordSize)) { // static field ciInstanceKlass* k = tinst->const_oop()->as_instance()->java_lang_Class_klass()->as_instance_klass(); field = k->get_field_by_offset(tinst->offset(), true); } else { ciInstanceKlass *k = tinst->klass()->as_instance_klass(); field = k->get_field_by_offset(tinst->offset(), false); } assert(field == NULL || original_field == NULL || (field->holder() == original_field->holder() && field->offset() == original_field->offset() && field->is_static() == original_field->is_static()), "wrong field?"); // Set field() and is_rewritable() attributes. if (field != NULL) alias_type(idx)->set_field(field); } } // Fill the cache for next time. ace->_adr_type = adr_type; ace->_index = idx; assert(alias_type(adr_type) == alias_type(idx), "type must be installed"); // Might as well try to fill the cache for the flattened version, too. AliasCacheEntry* face = probe_alias_cache(flat); if (face->_adr_type == NULL) { face->_adr_type = flat; face->_index = idx; assert(alias_type(flat) == alias_type(idx), "flat type must work too"); } return alias_type(idx); } Compile::AliasType* Compile::alias_type(ciField* field) { const TypeOopPtr* t; if (field->is_static()) t = TypeInstPtr::make(field->holder()->java_mirror()); else t = TypeOopPtr::make_from_klass_raw(field->holder()); AliasType* atp = alias_type(t->add_offset(field->offset_in_bytes()), field); assert(field->is_final() == !atp->is_rewritable(), "must get the rewritable bits correct"); return atp; } //------------------------------have_alias_type-------------------------------- bool Compile::have_alias_type(const TypePtr* adr_type) { AliasCacheEntry* ace = probe_alias_cache(adr_type); if (ace->_adr_type == adr_type) { return true; } // Handle special cases. if (adr_type == NULL) return true; if (adr_type == TypePtr::BOTTOM) return true; return find_alias_type(adr_type, true, NULL) != NULL; } //-----------------------------must_alias-------------------------------------- // True if all values of the given address type are in the given alias category. bool Compile::must_alias(const TypePtr* adr_type, int alias_idx) { if (alias_idx == AliasIdxBot) return true; // the universal category if (adr_type == NULL) return true; // NULL serves as TypePtr::TOP if (alias_idx == AliasIdxTop) return false; // the empty category if (adr_type->base() == Type::AnyPtr) return false; // TypePtr::BOTTOM or its twins // the only remaining possible overlap is identity int adr_idx = get_alias_index(adr_type); assert(adr_idx != AliasIdxBot && adr_idx != AliasIdxTop, ""); assert(adr_idx == alias_idx || (alias_type(alias_idx)->adr_type() != TypeOopPtr::BOTTOM && adr_type != TypeOopPtr::BOTTOM), "should not be testing for overlap with an unsafe pointer"); return adr_idx == alias_idx; } //------------------------------can_alias-------------------------------------- // True if any values of the given address type are in the given alias category. bool Compile::can_alias(const TypePtr* adr_type, int alias_idx) { if (alias_idx == AliasIdxTop) return false; // the empty category if (adr_type == NULL) return false; // NULL serves as TypePtr::TOP if (alias_idx == AliasIdxBot) return true; // the universal category if (adr_type->base() == Type::AnyPtr) return true; // TypePtr::BOTTOM or its twins // the only remaining possible overlap is identity int adr_idx = get_alias_index(adr_type); assert(adr_idx != AliasIdxBot && adr_idx != AliasIdxTop, ""); return adr_idx == alias_idx; } //---------------------------pop_warm_call------------------------------------- WarmCallInfo* Compile::pop_warm_call() { WarmCallInfo* wci = _warm_calls; if (wci != NULL) _warm_calls = wci->remove_from(wci); return wci; } //----------------------------Inline_Warm-------------------------------------- int Compile::Inline_Warm() { // If there is room, try to inline some more warm call sites. // %%% Do a graph index compaction pass when we think we're out of space? if (!InlineWarmCalls) return 0; int calls_made_hot = 0; int room_to_grow = NodeCountInliningCutoff - unique(); int amount_to_grow = MIN2(room_to_grow, (int)NodeCountInliningStep); int amount_grown = 0; WarmCallInfo* call; while (amount_to_grow > 0 && (call = pop_warm_call()) != NULL) { int est_size = (int)call->size(); if (est_size > (room_to_grow - amount_grown)) { // This one won't fit anyway. Get rid of it. call->make_cold(); continue; } call->make_hot(); calls_made_hot++; amount_grown += est_size; amount_to_grow -= est_size; } if (calls_made_hot > 0) set_major_progress(); return calls_made_hot; } //----------------------------Finish_Warm-------------------------------------- void Compile::Finish_Warm() { if (!InlineWarmCalls) return; if (failing()) return; if (warm_calls() == NULL) return; // Clean up loose ends, if we are out of space for inlining. WarmCallInfo* call; while ((call = pop_warm_call()) != NULL) { call->make_cold(); } } //---------------------cleanup_loop_predicates----------------------- // Remove the opaque nodes that protect the predicates so that all unused // checks and uncommon_traps will be eliminated from the ideal graph void Compile::cleanup_loop_predicates(PhaseIterGVN &igvn) { if (predicate_count()==0) return; for (int i = predicate_count(); i > 0; i--) { Node * n = predicate_opaque1_node(i-1); assert(n->Opcode() == Op_Opaque1, "must be"); igvn.replace_node(n, n->in(1)); } assert(predicate_count()==0, "should be clean!"); } // StringOpts and late inlining of string methods void Compile::inline_string_calls(bool parse_time) { { // remove useless nodes to make the usage analysis simpler ResourceMark rm; PhaseRemoveUseless pru(initial_gvn(), for_igvn()); } { ResourceMark rm; print_method("Before StringOpts", 3); PhaseStringOpts pso(initial_gvn(), for_igvn()); print_method("After StringOpts", 3); } // now inline anything that we skipped the first time around if (!parse_time) { _late_inlines_pos = _late_inlines.length(); } while (_string_late_inlines.length() > 0) { CallGenerator* cg = _string_late_inlines.pop(); cg->do_late_inline(); if (failing()) return; } _string_late_inlines.trunc_to(0); } void Compile::inline_incrementally_one(PhaseIterGVN& igvn) { assert(IncrementalInline, "incremental inlining should be on"); PhaseGVN* gvn = initial_gvn(); set_inlining_progress(false); for_igvn()->clear(); gvn->replace_with(&igvn); int i = 0; for (; i <_late_inlines.length() && !inlining_progress(); i++) { CallGenerator* cg = _late_inlines.at(i); _late_inlines_pos = i+1; cg->do_late_inline(); if (failing()) return; } int j = 0; for (; i < _late_inlines.length(); i++, j++) { _late_inlines.at_put(j, _late_inlines.at(i)); } _late_inlines.trunc_to(j); { ResourceMark rm; PhaseRemoveUseless pru(C->initial_gvn(), C->for_igvn()); } igvn = PhaseIterGVN(gvn); } // Perform incremental inlining until bound on number of live nodes is reached void Compile::inline_incrementally(PhaseIterGVN& igvn) { PhaseGVN* gvn = initial_gvn(); set_inlining_incrementally(true); set_inlining_progress(true); uint low_live_nodes = 0; while(inlining_progress() && _late_inlines.length() > 0) { if (live_nodes() > (uint)LiveNodeCountInliningCutoff) { if (low_live_nodes < (uint)LiveNodeCountInliningCutoff * 8 / 10) { // PhaseIdealLoop is expensive so we only try it once we are // out of loop and we only try it again if the previous helped // got the number of nodes down significantly PhaseIdealLoop ideal_loop( igvn, false, true ); if (failing()) return; low_live_nodes = live_nodes(); _major_progress = true; } if (live_nodes() > (uint)LiveNodeCountInliningCutoff) { break; } } inline_incrementally_one(igvn); if (failing()) return; igvn.optimize(); if (failing()) return; } assert( igvn._worklist.size() == 0, "should be done with igvn" ); if (_string_late_inlines.length() > 0) { assert(has_stringbuilder(), "inconsistent"); for_igvn()->clear(); initial_gvn()->replace_with(&igvn); inline_string_calls(false); if (failing()) return; { ResourceMark rm; PhaseRemoveUseless pru(initial_gvn(), for_igvn()); } igvn = PhaseIterGVN(gvn); igvn.optimize(); } set_inlining_incrementally(false); } //------------------------------Optimize--------------------------------------- // Given a graph, optimize it. void Compile::Optimize() { TracePhase t1("optimizer", &_t_optimizer, true); #ifndef PRODUCT if (env()->break_at_compile()) { BREAKPOINT; } #endif ResourceMark rm; int loop_opts_cnt; NOT_PRODUCT( verify_graph_edges(); ) print_method("After Parsing"); { // Iterative Global Value Numbering, including ideal transforms // Initialize IterGVN with types and values from parse-time GVN PhaseIterGVN igvn(initial_gvn()); { NOT_PRODUCT( TracePhase t2("iterGVN", &_t_iterGVN, TimeCompiler); ) igvn.optimize(); } print_method("Iter GVN 1", 2); if (failing()) return; inline_incrementally(igvn); print_method("Incremental Inline", 2); if (failing()) return; // No more new expensive nodes will be added to the list from here // so keep only the actual candidates for optimizations. cleanup_expensive_nodes(igvn); // Perform escape analysis if (_do_escape_analysis && ConnectionGraph::has_candidates(this)) { if (has_loops()) { // Cleanup graph (remove dead nodes). TracePhase t2("idealLoop", &_t_idealLoop, true); PhaseIdealLoop ideal_loop( igvn, false, true ); if (major_progress()) print_method("PhaseIdealLoop before EA", 2); if (failing()) return; } ConnectionGraph::do_analysis(this, &igvn); if (failing()) return; // Optimize out fields loads from scalar replaceable allocations. igvn.optimize(); print_method("Iter GVN after EA", 2); if (failing()) return; if (congraph() != NULL && macro_count() > 0) { NOT_PRODUCT( TracePhase t2("macroEliminate", &_t_macroEliminate, TimeCompiler); ) PhaseMacroExpand mexp(igvn); mexp.eliminate_macro_nodes(); igvn.set_delay_transform(false); igvn.optimize(); print_method("Iter GVN after eliminating allocations and locks", 2); if (failing()) return; } } // Loop transforms on the ideal graph. Range Check Elimination, // peeling, unrolling, etc. // Set loop opts counter loop_opts_cnt = num_loop_opts(); if((loop_opts_cnt > 0) && (has_loops() || has_split_ifs())) { { TracePhase t2("idealLoop", &_t_idealLoop, true); PhaseIdealLoop ideal_loop( igvn, true ); loop_opts_cnt--; if (major_progress()) print_method("PhaseIdealLoop 1", 2); if (failing()) return; } // Loop opts pass if partial peeling occurred in previous pass if(PartialPeelLoop && major_progress() && (loop_opts_cnt > 0)) { TracePhase t3("idealLoop", &_t_idealLoop, true); PhaseIdealLoop ideal_loop( igvn, false ); loop_opts_cnt--; if (major_progress()) print_method("PhaseIdealLoop 2", 2); if (failing()) return; } // Loop opts pass for loop-unrolling before CCP if(major_progress() && (loop_opts_cnt > 0)) { TracePhase t4("idealLoop", &_t_idealLoop, true); PhaseIdealLoop ideal_loop( igvn, false ); loop_opts_cnt--; if (major_progress()) print_method("PhaseIdealLoop 3", 2); } if (!failing()) { // Verify that last round of loop opts produced a valid graph NOT_PRODUCT( TracePhase t2("idealLoopVerify", &_t_idealLoopVerify, TimeCompiler); ) PhaseIdealLoop::verify(igvn); } } if (failing()) return; // Conditional Constant Propagation; PhaseCCP ccp( &igvn ); assert( true, "Break here to ccp.dump_nodes_and_types(_root,999,1)"); { TracePhase t2("ccp", &_t_ccp, true); ccp.do_transform(); } print_method("PhaseCPP 1", 2); assert( true, "Break here to ccp.dump_old2new_map()"); // Iterative Global Value Numbering, including ideal transforms { NOT_PRODUCT( TracePhase t2("iterGVN2", &_t_iterGVN2, TimeCompiler); ) igvn = ccp; igvn.optimize(); } print_method("Iter GVN 2", 2); if (failing()) return; // Loop transforms on the ideal graph. Range Check Elimination, // peeling, unrolling, etc. if(loop_opts_cnt > 0) { debug_only( int cnt = 0; ); while(major_progress() && (loop_opts_cnt > 0)) { TracePhase t2("idealLoop", &_t_idealLoop, true); assert( cnt++ < 40, "infinite cycle in loop optimization" ); PhaseIdealLoop ideal_loop( igvn, true); loop_opts_cnt--; if (major_progress()) print_method("PhaseIdealLoop iterations", 2); if (failing()) return; } } { // Verify that all previous optimizations produced a valid graph // at least to this point, even if no loop optimizations were done. NOT_PRODUCT( TracePhase t2("idealLoopVerify", &_t_idealLoopVerify, TimeCompiler); ) PhaseIdealLoop::verify(igvn); } { NOT_PRODUCT( TracePhase t2("macroExpand", &_t_macroExpand, TimeCompiler); ) PhaseMacroExpand mex(igvn); if (mex.expand_macro_nodes()) { assert(failing(), "must bail out w/ explicit message"); return; } } } // (End scope of igvn; run destructor if necessary for asserts.) dump_inlining(); // A method with only infinite loops has no edges entering loops from root { NOT_PRODUCT( TracePhase t2("graphReshape", &_t_graphReshaping, TimeCompiler); ) if (final_graph_reshaping()) { assert(failing(), "must bail out w/ explicit message"); return; } } print_method("Optimize finished", 2); } //------------------------------Code_Gen--------------------------------------- // Given a graph, generate code for it void Compile::Code_Gen() { if (failing()) return; // Perform instruction selection. You might think we could reclaim Matcher // memory PDQ, but actually the Matcher is used in generating spill code. // Internals of the Matcher (including some VectorSets) must remain live // for awhile - thus I cannot reclaim Matcher memory lest a VectorSet usage // set a bit in reclaimed memory. // In debug mode can dump m._nodes.dump() for mapping of ideal to machine // nodes. Mapping is only valid at the root of each matched subtree. NOT_PRODUCT( verify_graph_edges(); ) Node_List proj_list; Matcher m(proj_list); _matcher = &m; { TracePhase t2("matcher", &_t_matcher, true); m.match(); } // In debug mode can dump m._nodes.dump() for mapping of ideal to machine // nodes. Mapping is only valid at the root of each matched subtree. NOT_PRODUCT( verify_graph_edges(); ) // If you have too many nodes, or if matching has failed, bail out check_node_count(0, "out of nodes matching instructions"); if (failing()) return; // Build a proper-looking CFG PhaseCFG cfg(node_arena(), root(), m); _cfg = &cfg; { NOT_PRODUCT( TracePhase t2("scheduler", &_t_scheduler, TimeCompiler); ) cfg.Dominators(); if (failing()) return; NOT_PRODUCT( verify_graph_edges(); ) cfg.Estimate_Block_Frequency(); cfg.GlobalCodeMotion(m,unique(),proj_list); if (failing()) return; print_method("Global code motion", 2); NOT_PRODUCT( verify_graph_edges(); ) debug_only( cfg.verify(); ) } NOT_PRODUCT( verify_graph_edges(); ) PhaseChaitin regalloc(unique(),cfg,m); _regalloc = ®alloc; { TracePhase t2("regalloc", &_t_registerAllocation, true); // Perform any platform dependent preallocation actions. This is used, // for example, to avoid taking an implicit null pointer exception // using the frame pointer on win95. _regalloc->pd_preallocate_hook(); // Perform register allocation. After Chaitin, use-def chains are // no longer accurate (at spill code) and so must be ignored. // Node->LRG->reg mappings are still accurate. _regalloc->Register_Allocate(); // Bail out if the allocator builds too many nodes if (failing()) return; } // Prior to register allocation we kept empty basic blocks in case the // the allocator needed a place to spill. After register allocation we // are not adding any new instructions. If any basic block is empty, we // can now safely remove it. { NOT_PRODUCT( TracePhase t2("blockOrdering", &_t_blockOrdering, TimeCompiler); ) cfg.remove_empty(); if (do_freq_based_layout()) { PhaseBlockLayout layout(cfg); } else { cfg.set_loop_alignment(); } cfg.fixup_flow(); } // Perform any platform dependent postallocation verifications. debug_only( _regalloc->pd_postallocate_verify_hook(); ) // Apply peephole optimizations if( OptoPeephole ) { NOT_PRODUCT( TracePhase t2("peephole", &_t_peephole, TimeCompiler); ) PhasePeephole peep( _regalloc, cfg); peep.do_transform(); } // Convert Nodes to instruction bits in a buffer { // %%%% workspace merge brought two timers together for one job TracePhase t2a("output", &_t_output, true); NOT_PRODUCT( TraceTime t2b(NULL, &_t_codeGeneration, TimeCompiler, false); ) Output(); } print_method("Final Code"); // He's dead, Jim. _cfg = (PhaseCFG*)0xdeadbeef; _regalloc = (PhaseChaitin*)0xdeadbeef; } //------------------------------dump_asm--------------------------------------- // Dump formatted assembly #ifndef PRODUCT void Compile::dump_asm(int *pcs, uint pc_limit) { bool cut_short = false; tty->print_cr("#"); tty->print("# "); _tf->dump(); tty->cr(); tty->print_cr("#"); // For all blocks int pc = 0x0; // Program counter char starts_bundle = ' '; _regalloc->dump_frame(); Node *n = NULL; for( uint i=0; i<_cfg->_num_blocks; i++ ) { if (VMThread::should_terminate()) { cut_short = true; break; } Block *b = _cfg->_blocks[i]; if (b->is_connector() && !Verbose) continue; n = b->_nodes[0]; if (pcs && n->_idx < pc_limit) tty->print("%3.3x ", pcs[n->_idx]); else tty->print(" "); b->dump_head( &_cfg->_bbs ); if (b->is_connector()) { tty->print_cr(" # Empty connector block"); } else if (b->num_preds() == 2 && b->pred(1)->is_CatchProj() && b->pred(1)->as_CatchProj()->_con == CatchProjNode::fall_through_index) { tty->print_cr(" # Block is sole successor of call"); } // For all instructions Node *delay = NULL; for( uint j = 0; j_nodes.size(); j++ ) { if (VMThread::should_terminate()) { cut_short = true; break; } n = b->_nodes[j]; if (valid_bundle_info(n)) { Bundle *bundle = node_bundling(n); if (bundle->used_in_unconditional_delay()) { delay = n; continue; } if (bundle->starts_bundle()) starts_bundle = '+'; } if (WizardMode) n->dump(); if( !n->is_Region() && // Dont print in the Assembly !n->is_Phi() && // a few noisely useless nodes !n->is_Proj() && !n->is_MachTemp() && !n->is_SafePointScalarObject() && !n->is_Catch() && // Would be nice to print exception table targets !n->is_MergeMem() && // Not very interesting !n->is_top() && // Debug info table constants !(n->is_Con() && !n->is_Mach())// Debug info table constants ) { if (pcs && n->_idx < pc_limit) tty->print("%3.3x", pcs[n->_idx]); else tty->print(" "); tty->print(" %c ", starts_bundle); starts_bundle = ' '; tty->print("\t"); n->format(_regalloc, tty); tty->cr(); } // If we have an instruction with a delay slot, and have seen a delay, // then back up and print it if (valid_bundle_info(n) && node_bundling(n)->use_unconditional_delay()) { assert(delay != NULL, "no unconditional delay instruction"); if (WizardMode) delay->dump(); if (node_bundling(delay)->starts_bundle()) starts_bundle = '+'; if (pcs && n->_idx < pc_limit) tty->print("%3.3x", pcs[n->_idx]); else tty->print(" "); tty->print(" %c ", starts_bundle); starts_bundle = ' '; tty->print("\t"); delay->format(_regalloc, tty); tty->print_cr(""); delay = NULL; } // Dump the exception table as well if( n->is_Catch() && (Verbose || WizardMode) ) { // Print the exception table for this offset _handler_table.print_subtable_for(pc); } } if (pcs && n->_idx < pc_limit) tty->print_cr("%3.3x", pcs[n->_idx]); else tty->print_cr(""); assert(cut_short || delay == NULL, "no unconditional delay branch"); } // End of per-block dump tty->print_cr(""); if (cut_short) tty->print_cr("*** disassembly is cut short ***"); } #endif //------------------------------Final_Reshape_Counts--------------------------- // This class defines counters to help identify when a method // may/must be executed using hardware with only 24-bit precision. struct Final_Reshape_Counts : public StackObj { int _call_count; // count non-inlined 'common' calls int _float_count; // count float ops requiring 24-bit precision int _double_count; // count double ops requiring more precision int _java_call_count; // count non-inlined 'java' calls int _inner_loop_count; // count loops which need alignment VectorSet _visited; // Visitation flags Node_List _tests; // Set of IfNodes & PCTableNodes Final_Reshape_Counts() : _call_count(0), _float_count(0), _double_count(0), _java_call_count(0), _inner_loop_count(0), _visited( Thread::current()->resource_area() ) { } void inc_call_count () { _call_count ++; } void inc_float_count () { _float_count ++; } void inc_double_count() { _double_count++; } void inc_java_call_count() { _java_call_count++; } void inc_inner_loop_count() { _inner_loop_count++; } int get_call_count () const { return _call_count ; } int get_float_count () const { return _float_count ; } int get_double_count() const { return _double_count; } int get_java_call_count() const { return _java_call_count; } int get_inner_loop_count() const { return _inner_loop_count; } }; static bool oop_offset_is_sane(const TypeInstPtr* tp) { ciInstanceKlass *k = tp->klass()->as_instance_klass(); // Make sure the offset goes inside the instance layout. return k->contains_field_offset(tp->offset()); // Note that OffsetBot and OffsetTop are very negative. } // Eliminate trivially redundant StoreCMs and accumulate their // precedence edges. void Compile::eliminate_redundant_card_marks(Node* n) { assert(n->Opcode() == Op_StoreCM, "expected StoreCM"); if (n->in(MemNode::Address)->outcnt() > 1) { // There are multiple users of the same address so it might be // possible to eliminate some of the StoreCMs Node* mem = n->in(MemNode::Memory); Node* adr = n->in(MemNode::Address); Node* val = n->in(MemNode::ValueIn); Node* prev = n; bool done = false; // Walk the chain of StoreCMs eliminating ones that match. As // long as it's a chain of single users then the optimization is // safe. Eliminating partially redundant StoreCMs would require // cloning copies down the other paths. while (mem->Opcode() == Op_StoreCM && mem->outcnt() == 1 && !done) { if (adr == mem->in(MemNode::Address) && val == mem->in(MemNode::ValueIn)) { // redundant StoreCM if (mem->req() > MemNode::OopStore) { // Hasn't been processed by this code yet. n->add_prec(mem->in(MemNode::OopStore)); } else { // Already converted to precedence edge for (uint i = mem->req(); i < mem->len(); i++) { // Accumulate any precedence edges if (mem->in(i) != NULL) { n->add_prec(mem->in(i)); } } // Everything above this point has been processed. done = true; } // Eliminate the previous StoreCM prev->set_req(MemNode::Memory, mem->in(MemNode::Memory)); assert(mem->outcnt() == 0, "should be dead"); mem->disconnect_inputs(NULL, this); } else { prev = mem; } mem = prev->in(MemNode::Memory); } } } //------------------------------final_graph_reshaping_impl---------------------- // Implement items 1-5 from final_graph_reshaping below. void Compile::final_graph_reshaping_impl( Node *n, Final_Reshape_Counts &frc) { if ( n->outcnt() == 0 ) return; // dead node uint nop = n->Opcode(); // Check for 2-input instruction with "last use" on right input. // Swap to left input. Implements item (2). if( n->req() == 3 && // two-input instruction n->in(1)->outcnt() > 1 && // left use is NOT a last use (!n->in(1)->is_Phi() || n->in(1)->in(2) != n) && // it is not data loop n->in(2)->outcnt() == 1 &&// right use IS a last use !n->in(2)->is_Con() ) { // right use is not a constant // Check for commutative opcode switch( nop ) { case Op_AddI: case Op_AddF: case Op_AddD: case Op_AddL: case Op_MaxI: case Op_MinI: case Op_MulI: case Op_MulF: case Op_MulD: case Op_MulL: case Op_AndL: case Op_XorL: case Op_OrL: case Op_AndI: case Op_XorI: case Op_OrI: { // Move "last use" input to left by swapping inputs n->swap_edges(1, 2); break; } default: break; } } #ifdef ASSERT if( n->is_Mem() ) { int alias_idx = get_alias_index(n->as_Mem()->adr_type()); assert( n->in(0) != NULL || alias_idx != Compile::AliasIdxRaw || // oop will be recorded in oop map if load crosses safepoint n->is_Load() && (n->as_Load()->bottom_type()->isa_oopptr() || LoadNode::is_immutable_value(n->in(MemNode::Address))), "raw memory operations should have control edge"); } #endif // Count FPU ops and common calls, implements item (3) switch( nop ) { // Count all float operations that may use FPU case Op_AddF: case Op_SubF: case Op_MulF: case Op_DivF: case Op_NegF: case Op_ModF: case Op_ConvI2F: case Op_ConF: case Op_CmpF: case Op_CmpF3: // case Op_ConvL2F: // longs are split into 32-bit halves frc.inc_float_count(); break; case Op_ConvF2D: case Op_ConvD2F: frc.inc_float_count(); frc.inc_double_count(); break; // Count all double operations that may use FPU case Op_AddD: case Op_SubD: case Op_MulD: case Op_DivD: case Op_NegD: case Op_ModD: case Op_ConvI2D: case Op_ConvD2I: // case Op_ConvL2D: // handled by leaf call // case Op_ConvD2L: // handled by leaf call case Op_ConD: case Op_CmpD: case Op_CmpD3: frc.inc_double_count(); break; case Op_Opaque1: // Remove Opaque Nodes before matching case Op_Opaque2: // Remove Opaque Nodes before matching n->subsume_by(n->in(1), this); break; case Op_CallStaticJava: case Op_CallJava: case Op_CallDynamicJava: frc.inc_java_call_count(); // Count java call site; case Op_CallRuntime: case Op_CallLeaf: case Op_CallLeafNoFP: { assert( n->is_Call(), "" ); CallNode *call = n->as_Call(); // Count call sites where the FP mode bit would have to be flipped. // Do not count uncommon runtime calls: // uncommon_trap, _complete_monitor_locking, _complete_monitor_unlocking, // _new_Java, _new_typeArray, _new_objArray, _rethrow_Java, ... if( !call->is_CallStaticJava() || !call->as_CallStaticJava()->_name ) { frc.inc_call_count(); // Count the call site } else { // See if uncommon argument is shared Node *n = call->in(TypeFunc::Parms); int nop = n->Opcode(); // Clone shared simple arguments to uncommon calls, item (1). if( n->outcnt() > 1 && !n->is_Proj() && nop != Op_CreateEx && nop != Op_CheckCastPP && nop != Op_DecodeN && nop != Op_DecodeNKlass && !n->is_Mem() ) { Node *x = n->clone(); call->set_req( TypeFunc::Parms, x ); } } break; } case Op_StoreD: case Op_LoadD: case Op_LoadD_unaligned: frc.inc_double_count(); goto handle_mem; case Op_StoreF: case Op_LoadF: frc.inc_float_count(); goto handle_mem; case Op_StoreCM: { // Convert OopStore dependence into precedence edge Node* prec = n->in(MemNode::OopStore); n->del_req(MemNode::OopStore); n->add_prec(prec); eliminate_redundant_card_marks(n); } // fall through case Op_StoreB: case Op_StoreC: case Op_StorePConditional: case Op_StoreI: case Op_StoreL: case Op_StoreIConditional: case Op_StoreLConditional: case Op_CompareAndSwapI: case Op_CompareAndSwapL: case Op_CompareAndSwapP: case Op_CompareAndSwapN: case Op_GetAndAddI: case Op_GetAndAddL: case Op_GetAndSetI: case Op_GetAndSetL: case Op_GetAndSetP: case Op_GetAndSetN: case Op_StoreP: case Op_StoreN: case Op_StoreNKlass: case Op_LoadB: case Op_LoadUB: case Op_LoadUS: case Op_LoadI: case Op_LoadKlass: case Op_LoadNKlass: case Op_LoadL: case Op_LoadL_unaligned: case Op_LoadPLocked: case Op_LoadP: case Op_LoadN: case Op_LoadRange: case Op_LoadS: { handle_mem: #ifdef ASSERT if( VerifyOptoOopOffsets ) { assert( n->is_Mem(), "" ); MemNode *mem = (MemNode*)n; // Check to see if address types have grounded out somehow. const TypeInstPtr *tp = mem->in(MemNode::Address)->bottom_type()->isa_instptr(); assert( !tp || oop_offset_is_sane(tp), "" ); } #endif break; } case Op_AddP: { // Assert sane base pointers Node *addp = n->in(AddPNode::Address); assert( !addp->is_AddP() || addp->in(AddPNode::Base)->is_top() || // Top OK for allocation addp->in(AddPNode::Base) == n->in(AddPNode::Base), "Base pointers must match" ); #ifdef _LP64 if ((UseCompressedOops || UseCompressedKlassPointers) && addp->Opcode() == Op_ConP && addp == n->in(AddPNode::Base) && n->in(AddPNode::Offset)->is_Con()) { // Use addressing with narrow klass to load with offset on x86. // On sparc loading 32-bits constant and decoding it have less // instructions (4) then load 64-bits constant (7). // Do this transformation here since IGVN will convert ConN back to ConP. const Type* t = addp->bottom_type(); if (t->isa_oopptr() || t->isa_klassptr()) { Node* nn = NULL; int op = t->isa_oopptr() ? Op_ConN : Op_ConNKlass; // Look for existing ConN node of the same exact type. Node* r = root(); uint cnt = r->outcnt(); for (uint i = 0; i < cnt; i++) { Node* m = r->raw_out(i); if (m!= NULL && m->Opcode() == op && m->bottom_type()->make_ptr() == t) { nn = m; break; } } if (nn != NULL) { // Decode a narrow oop to match address // [R12 + narrow_oop_reg<<3 + offset] if (t->isa_oopptr()) { nn = new (this) DecodeNNode(nn, t); } else { nn = new (this) DecodeNKlassNode(nn, t); } n->set_req(AddPNode::Base, nn); n->set_req(AddPNode::Address, nn); if (addp->outcnt() == 0) { addp->disconnect_inputs(NULL, this); } } } } #endif break; } #ifdef _LP64 case Op_CastPP: if (n->in(1)->is_DecodeN() && Matcher::gen_narrow_oop_implicit_null_checks()) { Node* in1 = n->in(1); const Type* t = n->bottom_type(); Node* new_in1 = in1->clone(); new_in1->as_DecodeN()->set_type(t); if (!Matcher::narrow_oop_use_complex_address()) { // // x86, ARM and friends can handle 2 adds in addressing mode // and Matcher can fold a DecodeN node into address by using // a narrow oop directly and do implicit NULL check in address: // // [R12 + narrow_oop_reg<<3 + offset] // NullCheck narrow_oop_reg // // On other platforms (Sparc) we have to keep new DecodeN node and // use it to do implicit NULL check in address: // // decode_not_null narrow_oop_reg, base_reg // [base_reg + offset] // NullCheck base_reg // // Pin the new DecodeN node to non-null path on these platform (Sparc) // to keep the information to which NULL check the new DecodeN node // corresponds to use it as value in implicit_null_check(). // new_in1->set_req(0, n->in(0)); } n->subsume_by(new_in1, this); if (in1->outcnt() == 0) { in1->disconnect_inputs(NULL, this); } } break; case Op_CmpP: // Do this transformation here to preserve CmpPNode::sub() and // other TypePtr related Ideal optimizations (for example, ptr nullness). if (n->in(1)->is_DecodeNarrowPtr() || n->in(2)->is_DecodeNarrowPtr()) { Node* in1 = n->in(1); Node* in2 = n->in(2); if (!in1->is_DecodeNarrowPtr()) { in2 = in1; in1 = n->in(2); } assert(in1->is_DecodeNarrowPtr(), "sanity"); Node* new_in2 = NULL; if (in2->is_DecodeNarrowPtr()) { assert(in2->Opcode() == in1->Opcode(), "must be same node type"); new_in2 = in2->in(1); } else if (in2->Opcode() == Op_ConP) { const Type* t = in2->bottom_type(); if (t == TypePtr::NULL_PTR) { assert(in1->is_DecodeN(), "compare klass to null?"); // Don't convert CmpP null check into CmpN if compressed // oops implicit null check is not generated. // This will allow to generate normal oop implicit null check. if (Matcher::gen_narrow_oop_implicit_null_checks()) new_in2 = ConNode::make(this, TypeNarrowOop::NULL_PTR); // // This transformation together with CastPP transformation above // will generated code for implicit NULL checks for compressed oops. // // The original code after Optimize() // // LoadN memory, narrow_oop_reg // decode narrow_oop_reg, base_reg // CmpP base_reg, NULL // CastPP base_reg // NotNull // Load [base_reg + offset], val_reg // // after these transformations will be // // LoadN memory, narrow_oop_reg // CmpN narrow_oop_reg, NULL // decode_not_null narrow_oop_reg, base_reg // Load [base_reg + offset], val_reg // // and the uncommon path (== NULL) will use narrow_oop_reg directly // since narrow oops can be used in debug info now (see the code in // final_graph_reshaping_walk()). // // At the end the code will be matched to // on x86: // // Load_narrow_oop memory, narrow_oop_reg // Load [R12 + narrow_oop_reg<<3 + offset], val_reg // NullCheck narrow_oop_reg // // and on sparc: // // Load_narrow_oop memory, narrow_oop_reg // decode_not_null narrow_oop_reg, base_reg // Load [base_reg + offset], val_reg // NullCheck base_reg // } else if (t->isa_oopptr()) { new_in2 = ConNode::make(this, t->make_narrowoop()); } else if (t->isa_klassptr()) { new_in2 = ConNode::make(this, t->make_narrowklass()); } } if (new_in2 != NULL) { Node* cmpN = new (this) CmpNNode(in1->in(1), new_in2); n->subsume_by(cmpN, this); if (in1->outcnt() == 0) { in1->disconnect_inputs(NULL, this); } if (in2->outcnt() == 0) { in2->disconnect_inputs(NULL, this); } } } break; case Op_DecodeN: case Op_DecodeNKlass: assert(!n->in(1)->is_EncodeNarrowPtr(), "should be optimized out"); // DecodeN could be pinned when it can't be fold into // an address expression, see the code for Op_CastPP above. assert(n->in(0) == NULL || (UseCompressedOops && !Matcher::narrow_oop_use_complex_address()), "no control"); break; case Op_EncodeP: case Op_EncodePKlass: { Node* in1 = n->in(1); if (in1->is_DecodeNarrowPtr()) { n->subsume_by(in1->in(1), this); } else if (in1->Opcode() == Op_ConP) { const Type* t = in1->bottom_type(); if (t == TypePtr::NULL_PTR) { assert(t->isa_oopptr(), "null klass?"); n->subsume_by(ConNode::make(this, TypeNarrowOop::NULL_PTR), this); } else if (t->isa_oopptr()) { n->subsume_by(ConNode::make(this, t->make_narrowoop()), this); } else if (t->isa_klassptr()) { n->subsume_by(ConNode::make(this, t->make_narrowklass()), this); } } if (in1->outcnt() == 0) { in1->disconnect_inputs(NULL, this); } break; } case Op_Proj: { if (OptimizeStringConcat) { ProjNode* p = n->as_Proj(); if (p->_is_io_use) { // Separate projections were used for the exception path which // are normally removed by a late inline. If it wasn't inlined // then they will hang around and should just be replaced with // the original one. Node* proj = NULL; // Replace with just one for (SimpleDUIterator i(p->in(0)); i.has_next(); i.next()) { Node *use = i.get(); if (use->is_Proj() && p != use && use->as_Proj()->_con == p->_con) { proj = use; break; } } assert(proj != NULL, "must be found"); p->subsume_by(proj, this); } } break; } case Op_Phi: if (n->as_Phi()->bottom_type()->isa_narrowoop() || n->as_Phi()->bottom_type()->isa_narrowklass()) { // The EncodeP optimization may create Phi with the same edges // for all paths. It is not handled well by Register Allocator. Node* unique_in = n->in(1); assert(unique_in != NULL, ""); uint cnt = n->req(); for (uint i = 2; i < cnt; i++) { Node* m = n->in(i); assert(m != NULL, ""); if (unique_in != m) unique_in = NULL; } if (unique_in != NULL) { n->subsume_by(unique_in, this); } } break; #endif case Op_ModI: if (UseDivMod) { // Check if a%b and a/b both exist Node* d = n->find_similar(Op_DivI); if (d) { // Replace them with a fused divmod if supported if (Matcher::has_match_rule(Op_DivModI)) { DivModINode* divmod = DivModINode::make(this, n); d->subsume_by(divmod->div_proj(), this); n->subsume_by(divmod->mod_proj(), this); } else { // replace a%b with a-((a/b)*b) Node* mult = new (this) MulINode(d, d->in(2)); Node* sub = new (this) SubINode(d->in(1), mult); n->subsume_by(sub, this); } } } break; case Op_ModL: if (UseDivMod) { // Check if a%b and a/b both exist Node* d = n->find_similar(Op_DivL); if (d) { // Replace them with a fused divmod if supported if (Matcher::has_match_rule(Op_DivModL)) { DivModLNode* divmod = DivModLNode::make(this, n); d->subsume_by(divmod->div_proj(), this); n->subsume_by(divmod->mod_proj(), this); } else { // replace a%b with a-((a/b)*b) Node* mult = new (this) MulLNode(d, d->in(2)); Node* sub = new (this) SubLNode(d->in(1), mult); n->subsume_by(sub, this); } } } break; case Op_LoadVector: case Op_StoreVector: break; case Op_PackB: case Op_PackS: case Op_PackI: case Op_PackF: case Op_PackL: case Op_PackD: if (n->req()-1 > 2) { // Replace many operand PackNodes with a binary tree for matching PackNode* p = (PackNode*) n; Node* btp = p->binary_tree_pack(this, 1, n->req()); n->subsume_by(btp, this); } break; case Op_Loop: case Op_CountedLoop: if (n->as_Loop()->is_inner_loop()) { frc.inc_inner_loop_count(); } break; case Op_LShiftI: case Op_RShiftI: case Op_URShiftI: case Op_LShiftL: case Op_RShiftL: case Op_URShiftL: if (Matcher::need_masked_shift_count) { // The cpu's shift instructions don't restrict the count to the // lower 5/6 bits. We need to do the masking ourselves. Node* in2 = n->in(2); juint mask = (n->bottom_type() == TypeInt::INT) ? (BitsPerInt - 1) : (BitsPerLong - 1); const TypeInt* t = in2->find_int_type(); if (t != NULL && t->is_con()) { juint shift = t->get_con(); if (shift > mask) { // Unsigned cmp n->set_req(2, ConNode::make(this, TypeInt::make(shift & mask))); } } else { if (t == NULL || t->_lo < 0 || t->_hi > (int)mask) { Node* shift = new (this) AndINode(in2, ConNode::make(this, TypeInt::make(mask))); n->set_req(2, shift); } } if (in2->outcnt() == 0) { // Remove dead node in2->disconnect_inputs(NULL, this); } } break; case Op_MemBarStoreStore: // Break the link with AllocateNode: it is no longer useful and // confuses register allocation. if (n->req() > MemBarNode::Precedent) { n->set_req(MemBarNode::Precedent, top()); } break; default: assert( !n->is_Call(), "" ); assert( !n->is_Mem(), "" ); break; } // Collect CFG split points if (n->is_MultiBranch()) frc._tests.push(n); } //------------------------------final_graph_reshaping_walk--------------------- // Replacing Opaque nodes with their input in final_graph_reshaping_impl(), // requires that the walk visits a node's inputs before visiting the node. void Compile::final_graph_reshaping_walk( Node_Stack &nstack, Node *root, Final_Reshape_Counts &frc ) { ResourceArea *area = Thread::current()->resource_area(); Unique_Node_List sfpt(area); frc._visited.set(root->_idx); // first, mark node as visited uint cnt = root->req(); Node *n = root; uint i = 0; while (true) { if (i < cnt) { // Place all non-visited non-null inputs onto stack Node* m = n->in(i); ++i; if (m != NULL && !frc._visited.test_set(m->_idx)) { if (m->is_SafePoint() && m->as_SafePoint()->jvms() != NULL) sfpt.push(m); cnt = m->req(); nstack.push(n, i); // put on stack parent and next input's index n = m; i = 0; } } else { // Now do post-visit work final_graph_reshaping_impl( n, frc ); if (nstack.is_empty()) break; // finished n = nstack.node(); // Get node from stack cnt = n->req(); i = nstack.index(); nstack.pop(); // Shift to the next node on stack } } // Skip next transformation if compressed oops are not used. if ((UseCompressedOops && !Matcher::gen_narrow_oop_implicit_null_checks()) || (!UseCompressedOops && !UseCompressedKlassPointers)) return; // Go over safepoints nodes to skip DecodeN/DecodeNKlass nodes for debug edges. // It could be done for an uncommon traps or any safepoints/calls // if the DecodeN/DecodeNKlass node is referenced only in a debug info. while (sfpt.size() > 0) { n = sfpt.pop(); JVMState *jvms = n->as_SafePoint()->jvms(); assert(jvms != NULL, "sanity"); int start = jvms->debug_start(); int end = n->req(); bool is_uncommon = (n->is_CallStaticJava() && n->as_CallStaticJava()->uncommon_trap_request() != 0); for (int j = start; j < end; j++) { Node* in = n->in(j); if (in->is_DecodeNarrowPtr()) { bool safe_to_skip = true; if (!is_uncommon ) { // Is it safe to skip? for (uint i = 0; i < in->outcnt(); i++) { Node* u = in->raw_out(i); if (!u->is_SafePoint() || u->is_Call() && u->as_Call()->has_non_debug_use(n)) { safe_to_skip = false; } } } if (safe_to_skip) { n->set_req(j, in->in(1)); } if (in->outcnt() == 0) { in->disconnect_inputs(NULL, this); } } } } } //------------------------------final_graph_reshaping-------------------------- // Final Graph Reshaping. // // (1) Clone simple inputs to uncommon calls, so they can be scheduled late // and not commoned up and forced early. Must come after regular // optimizations to avoid GVN undoing the cloning. Clone constant // inputs to Loop Phis; these will be split by the allocator anyways. // Remove Opaque nodes. // (2) Move last-uses by commutative operations to the left input to encourage // Intel update-in-place two-address operations and better register usage // on RISCs. Must come after regular optimizations to avoid GVN Ideal // calls canonicalizing them back. // (3) Count the number of double-precision FP ops, single-precision FP ops // and call sites. On Intel, we can get correct rounding either by // forcing singles to memory (requires extra stores and loads after each // FP bytecode) or we can set a rounding mode bit (requires setting and // clearing the mode bit around call sites). The mode bit is only used // if the relative frequency of single FP ops to calls is low enough. // This is a key transform for SPEC mpeg_audio. // (4) Detect infinite loops; blobs of code reachable from above but not // below. Several of the Code_Gen algorithms fail on such code shapes, // so we simply bail out. Happens a lot in ZKM.jar, but also happens // from time to time in other codes (such as -Xcomp finalizer loops, etc). // Detection is by looking for IfNodes where only 1 projection is // reachable from below or CatchNodes missing some targets. // (5) Assert for insane oop offsets in debug mode. bool Compile::final_graph_reshaping() { // an infinite loop may have been eliminated by the optimizer, // in which case the graph will be empty. if (root()->req() == 1) { record_method_not_compilable("trivial infinite loop"); return true; } // Expensive nodes have their control input set to prevent the GVN // from freely commoning them. There's no GVN beyond this point so // no need to keep the control input. We want the expensive nodes to // be freely moved to the least frequent code path by gcm. assert(OptimizeExpensiveOps || expensive_count() == 0, "optimization off but list non empty?"); for (int i = 0; i < expensive_count(); i++) { _expensive_nodes->at(i)->set_req(0, NULL); } Final_Reshape_Counts frc; // Visit everybody reachable! // Allocate stack of size C->unique()/2 to avoid frequent realloc Node_Stack nstack(unique() >> 1); final_graph_reshaping_walk(nstack, root(), frc); // Check for unreachable (from below) code (i.e., infinite loops). for( uint i = 0; i < frc._tests.size(); i++ ) { MultiBranchNode *n = frc._tests[i]->as_MultiBranch(); // Get number of CFG targets. // Note that PCTables include exception targets after calls. uint required_outcnt = n->required_outcnt(); if (n->outcnt() != required_outcnt) { // Check for a few special cases. Rethrow Nodes never take the // 'fall-thru' path, so expected kids is 1 less. if (n->is_PCTable() && n->in(0) && n->in(0)->in(0)) { if (n->in(0)->in(0)->is_Call()) { CallNode *call = n->in(0)->in(0)->as_Call(); if (call->entry_point() == OptoRuntime::rethrow_stub()) { required_outcnt--; // Rethrow always has 1 less kid } else if (call->req() > TypeFunc::Parms && call->is_CallDynamicJava()) { // Check for null receiver. In such case, the optimizer has // detected that the virtual call will always result in a null // pointer exception. The fall-through projection of this CatchNode // will not be populated. Node *arg0 = call->in(TypeFunc::Parms); if (arg0->is_Type() && arg0->as_Type()->type()->higher_equal(TypePtr::NULL_PTR)) { required_outcnt--; } } else if (call->entry_point() == OptoRuntime::new_array_Java() && call->req() > TypeFunc::Parms+1 && call->is_CallStaticJava()) { // Check for negative array length. In such case, the optimizer has // detected that the allocation attempt will always result in an // exception. There is no fall-through projection of this CatchNode . Node *arg1 = call->in(TypeFunc::Parms+1); if (arg1->is_Type() && arg1->as_Type()->type()->join(TypeInt::POS)->empty()) { required_outcnt--; } } } } // Recheck with a better notion of 'required_outcnt' if (n->outcnt() != required_outcnt) { record_method_not_compilable("malformed control flow"); return true; // Not all targets reachable! } } // Check that I actually visited all kids. Unreached kids // must be infinite loops. for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) if (!frc._visited.test(n->fast_out(j)->_idx)) { record_method_not_compilable("infinite loop"); return true; // Found unvisited kid; must be unreach } } // If original bytecodes contained a mixture of floats and doubles // check if the optimizer has made it homogenous, item (3). if( Use24BitFPMode && Use24BitFP && UseSSE == 0 && frc.get_float_count() > 32 && frc.get_double_count() == 0 && (10 * frc.get_call_count() < frc.get_float_count()) ) { set_24_bit_selection_and_mode( false, true ); } set_java_calls(frc.get_java_call_count()); set_inner_loops(frc.get_inner_loop_count()); // No infinite loops, no reason to bail out. return false; } //-----------------------------too_many_traps---------------------------------- // Report if there are too many traps at the current method and bci. // Return true if there was a trap, and/or PerMethodTrapLimit is exceeded. bool Compile::too_many_traps(ciMethod* method, int bci, Deoptimization::DeoptReason reason) { ciMethodData* md = method->method_data(); if (md->is_empty()) { // Assume the trap has not occurred, or that it occurred only // because of a transient condition during start-up in the interpreter. return false; } if (md->has_trap_at(bci, reason) != 0) { // Assume PerBytecodeTrapLimit==0, for a more conservative heuristic. // Also, if there are multiple reasons, or if there is no per-BCI record, // assume the worst. if (log()) log()->elem("observe trap='%s' count='%d'", Deoptimization::trap_reason_name(reason), md->trap_count(reason)); return true; } else { // Ignore method/bci and see if there have been too many globally. return too_many_traps(reason, md); } } // Less-accurate variant which does not require a method and bci. bool Compile::too_many_traps(Deoptimization::DeoptReason reason, ciMethodData* logmd) { if (trap_count(reason) >= (uint)PerMethodTrapLimit) { // Too many traps globally. // Note that we use cumulative trap_count, not just md->trap_count. if (log()) { int mcount = (logmd == NULL)? -1: (int)logmd->trap_count(reason); log()->elem("observe trap='%s' count='0' mcount='%d' ccount='%d'", Deoptimization::trap_reason_name(reason), mcount, trap_count(reason)); } return true; } else { // The coast is clear. return false; } } //--------------------------too_many_recompiles-------------------------------- // Report if there are too many recompiles at the current method and bci. // Consults PerBytecodeRecompilationCutoff and PerMethodRecompilationCutoff. // Is not eager to return true, since this will cause the compiler to use // Action_none for a trap point, to avoid too many recompilations. bool Compile::too_many_recompiles(ciMethod* method, int bci, Deoptimization::DeoptReason reason) { ciMethodData* md = method->method_data(); if (md->is_empty()) { // Assume the trap has not occurred, or that it occurred only // because of a transient condition during start-up in the interpreter. return false; } // Pick a cutoff point well within PerBytecodeRecompilationCutoff. uint bc_cutoff = (uint) PerBytecodeRecompilationCutoff / 8; uint m_cutoff = (uint) PerMethodRecompilationCutoff / 2 + 1; // not zero Deoptimization::DeoptReason per_bc_reason = Deoptimization::reason_recorded_per_bytecode_if_any(reason); if ((per_bc_reason == Deoptimization::Reason_none || md->has_trap_at(bci, reason) != 0) // The trap frequency measure we care about is the recompile count: && md->trap_recompiled_at(bci) && md->overflow_recompile_count() >= bc_cutoff) { // Do not emit a trap here if it has already caused recompilations. // Also, if there are multiple reasons, or if there is no per-BCI record, // assume the worst. if (log()) log()->elem("observe trap='%s recompiled' count='%d' recompiles2='%d'", Deoptimization::trap_reason_name(reason), md->trap_count(reason), md->overflow_recompile_count()); return true; } else if (trap_count(reason) != 0 && decompile_count() >= m_cutoff) { // Too many recompiles globally, and we have seen this sort of trap. // Use cumulative decompile_count, not just md->decompile_count. if (log()) log()->elem("observe trap='%s' count='%d' mcount='%d' decompiles='%d' mdecompiles='%d'", Deoptimization::trap_reason_name(reason), md->trap_count(reason), trap_count(reason), md->decompile_count(), decompile_count()); return true; } else { // The coast is clear. return false; } } #ifndef PRODUCT //------------------------------verify_graph_edges--------------------------- // Walk the Graph and verify that there is a one-to-one correspondence // between Use-Def edges and Def-Use edges in the graph. void Compile::verify_graph_edges(bool no_dead_code) { if (VerifyGraphEdges) { ResourceArea *area = Thread::current()->resource_area(); Unique_Node_List visited(area); // Call recursive graph walk to check edges _root->verify_edges(visited); if (no_dead_code) { // Now make sure that no visited node is used by an unvisited node. bool dead_nodes = 0; Unique_Node_List checked(area); while (visited.size() > 0) { Node* n = visited.pop(); checked.push(n); for (uint i = 0; i < n->outcnt(); i++) { Node* use = n->raw_out(i); if (checked.member(use)) continue; // already checked if (visited.member(use)) continue; // already in the graph if (use->is_Con()) continue; // a dead ConNode is OK // At this point, we have found a dead node which is DU-reachable. if (dead_nodes++ == 0) tty->print_cr("*** Dead nodes reachable via DU edges:"); use->dump(2); tty->print_cr("---"); checked.push(use); // No repeats; pretend it is now checked. } } assert(dead_nodes == 0, "using nodes must be reachable from root"); } } } #endif // The Compile object keeps track of failure reasons separately from the ciEnv. // This is required because there is not quite a 1-1 relation between the // ciEnv and its compilation task and the Compile object. Note that one // ciEnv might use two Compile objects, if C2Compiler::compile_method decides // to backtrack and retry without subsuming loads. Other than this backtracking // behavior, the Compile's failure reason is quietly copied up to the ciEnv // by the logic in C2Compiler. void Compile::record_failure(const char* reason) { if (log() != NULL) { log()->elem("failure reason='%s' phase='compile'", reason); } if (_failure_reason == NULL) { // Record the first failure reason. _failure_reason = reason; } if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) { C->print_method(_failure_reason); } _root = NULL; // flush the graph, too } Compile::TracePhase::TracePhase(const char* name, elapsedTimer* accumulator, bool dolog) : TraceTime(NULL, accumulator, false NOT_PRODUCT( || TimeCompiler ), false), _phase_name(name), _dolog(dolog) { if (dolog) { C = Compile::current(); _log = C->log(); } else { C = NULL; _log = NULL; } if (_log != NULL) { _log->begin_head("phase name='%s' nodes='%d' live='%d'", _phase_name, C->unique(), C->live_nodes()); _log->stamp(); _log->end_head(); } } Compile::TracePhase::~TracePhase() { C = Compile::current(); if (_dolog) { _log = C->log(); } else { _log = NULL; } #ifdef ASSERT if (PrintIdealNodeCount) { tty->print_cr("phase name='%s' nodes='%d' live='%d' live_graph_walk='%d'", _phase_name, C->unique(), C->live_nodes(), C->count_live_nodes_by_graph_walk()); } if (VerifyIdealNodeCount) { Compile::current()->print_missing_nodes(); } #endif if (_log != NULL) { _log->done("phase name='%s' nodes='%d' live='%d'", _phase_name, C->unique(), C->live_nodes()); } } //============================================================================= // Two Constant's are equal when the type and the value are equal. bool Compile::Constant::operator==(const Constant& other) { if (type() != other.type() ) return false; if (can_be_reused() != other.can_be_reused()) return false; // For floating point values we compare the bit pattern. switch (type()) { case T_FLOAT: return (_v._value.i == other._v._value.i); case T_LONG: case T_DOUBLE: return (_v._value.j == other._v._value.j); case T_OBJECT: case T_ADDRESS: return (_v._value.l == other._v._value.l); case T_VOID: return (_v._value.l == other._v._value.l); // jump-table entries case T_METADATA: return (_v._metadata == other._v._metadata); default: ShouldNotReachHere(); } return false; } static int type_to_size_in_bytes(BasicType t) { switch (t) { case T_LONG: return sizeof(jlong ); case T_FLOAT: return sizeof(jfloat ); case T_DOUBLE: return sizeof(jdouble); case T_METADATA: return sizeof(Metadata*); // We use T_VOID as marker for jump-table entries (labels) which // need an internal word relocation. case T_VOID: case T_ADDRESS: case T_OBJECT: return sizeof(jobject); } ShouldNotReachHere(); return -1; } int Compile::ConstantTable::qsort_comparator(Constant* a, Constant* b) { // sort descending if (a->freq() > b->freq()) return -1; if (a->freq() < b->freq()) return 1; return 0; } void Compile::ConstantTable::calculate_offsets_and_size() { // First, sort the array by frequencies. _constants.sort(qsort_comparator); #ifdef ASSERT // Make sure all jump-table entries were sorted to the end of the // array (they have a negative frequency). bool found_void = false; for (int i = 0; i < _constants.length(); i++) { Constant con = _constants.at(i); if (con.type() == T_VOID) found_void = true; // jump-tables else assert(!found_void, "wrong sorting"); } #endif int offset = 0; for (int i = 0; i < _constants.length(); i++) { Constant* con = _constants.adr_at(i); // Align offset for type. int typesize = type_to_size_in_bytes(con->type()); offset = align_size_up(offset, typesize); con->set_offset(offset); // set constant's offset if (con->type() == T_VOID) { MachConstantNode* n = (MachConstantNode*) con->get_jobject(); offset = offset + typesize * n->outcnt(); // expand jump-table } else { offset = offset + typesize; } } // Align size up to the next section start (which is insts; see // CodeBuffer::align_at_start). assert(_size == -1, "already set?"); _size = align_size_up(offset, CodeEntryAlignment); } void Compile::ConstantTable::emit(CodeBuffer& cb) { MacroAssembler _masm(&cb); for (int i = 0; i < _constants.length(); i++) { Constant con = _constants.at(i); address constant_addr; switch (con.type()) { case T_LONG: constant_addr = _masm.long_constant( con.get_jlong() ); break; case T_FLOAT: constant_addr = _masm.float_constant( con.get_jfloat() ); break; case T_DOUBLE: constant_addr = _masm.double_constant(con.get_jdouble()); break; case T_OBJECT: { jobject obj = con.get_jobject(); int oop_index = _masm.oop_recorder()->find_index(obj); constant_addr = _masm.address_constant((address) obj, oop_Relocation::spec(oop_index)); break; } case T_ADDRESS: { address addr = (address) con.get_jobject(); constant_addr = _masm.address_constant(addr); break; } // We use T_VOID as marker for jump-table entries (labels) which // need an internal word relocation. case T_VOID: { MachConstantNode* n = (MachConstantNode*) con.get_jobject(); // Fill the jump-table with a dummy word. The real value is // filled in later in fill_jump_table. address dummy = (address) n; constant_addr = _masm.address_constant(dummy); // Expand jump-table for (uint i = 1; i < n->outcnt(); i++) { address temp_addr = _masm.address_constant(dummy + i); assert(temp_addr, "consts section too small"); } break; } case T_METADATA: { Metadata* obj = con.get_metadata(); int metadata_index = _masm.oop_recorder()->find_index(obj); constant_addr = _masm.address_constant((address) obj, metadata_Relocation::spec(metadata_index)); break; } default: ShouldNotReachHere(); } assert(constant_addr, "consts section too small"); assert((constant_addr - _masm.code()->consts()->start()) == con.offset(), err_msg_res("must be: %d == %d", constant_addr - _masm.code()->consts()->start(), con.offset())); } } int Compile::ConstantTable::find_offset(Constant& con) const { int idx = _constants.find(con); assert(idx != -1, "constant must be in constant table"); int offset = _constants.at(idx).offset(); assert(offset != -1, "constant table not emitted yet?"); return offset; } void Compile::ConstantTable::add(Constant& con) { if (con.can_be_reused()) { int idx = _constants.find(con); if (idx != -1 && _constants.at(idx).can_be_reused()) { _constants.adr_at(idx)->inc_freq(con.freq()); // increase the frequency by the current value return; } } (void) _constants.append(con); } Compile::Constant Compile::ConstantTable::add(MachConstantNode* n, BasicType type, jvalue value) { Block* b = Compile::current()->cfg()->_bbs[n->_idx]; Constant con(type, value, b->_freq); add(con); return con; } Compile::Constant Compile::ConstantTable::add(Metadata* metadata) { Constant con(metadata); add(con); return con; } Compile::Constant Compile::ConstantTable::add(MachConstantNode* n, MachOper* oper) { jvalue value; BasicType type = oper->type()->basic_type(); switch (type) { case T_LONG: value.j = oper->constantL(); break; case T_FLOAT: value.f = oper->constantF(); break; case T_DOUBLE: value.d = oper->constantD(); break; case T_OBJECT: case T_ADDRESS: value.l = (jobject) oper->constant(); break; case T_METADATA: return add((Metadata*)oper->constant()); break; default: guarantee(false, err_msg_res("unhandled type: %s", type2name(type))); } return add(n, type, value); } Compile::Constant Compile::ConstantTable::add_jump_table(MachConstantNode* n) { jvalue value; // We can use the node pointer here to identify the right jump-table // as this method is called from Compile::Fill_buffer right before // the MachNodes are emitted and the jump-table is filled (means the // MachNode pointers do not change anymore). value.l = (jobject) n; Constant con(T_VOID, value, next_jump_table_freq(), false); // Labels of a jump-table cannot be reused. add(con); return con; } void Compile::ConstantTable::fill_jump_table(CodeBuffer& cb, MachConstantNode* n, GrowableArray labels) const { // If called from Compile::scratch_emit_size do nothing. if (Compile::current()->in_scratch_emit_size()) return; assert(labels.is_nonempty(), "must be"); assert((uint) labels.length() == n->outcnt(), err_msg_res("must be equal: %d == %d", labels.length(), n->outcnt())); // Since MachConstantNode::constant_offset() also contains // table_base_offset() we need to subtract the table_base_offset() // to get the plain offset into the constant table. int offset = n->constant_offset() - table_base_offset(); MacroAssembler _masm(&cb); address* jump_table_base = (address*) (_masm.code()->consts()->start() + offset); for (uint i = 0; i < n->outcnt(); i++) { address* constant_addr = &jump_table_base[i]; assert(*constant_addr == (((address) n) + i), err_msg_res("all jump-table entries must contain adjusted node pointer: " INTPTR_FORMAT " == " INTPTR_FORMAT, *constant_addr, (((address) n) + i))); *constant_addr = cb.consts()->target(*labels.at(i), (address) constant_addr); cb.consts()->relocate((address) constant_addr, relocInfo::internal_word_type); } } void Compile::dump_inlining() { if (PrintInlining || PrintIntrinsics NOT_PRODUCT( || PrintOptoInlining)) { // Print inlining message for candidates that we couldn't inline // for lack of space or non constant receiver for (int i = 0; i < _late_inlines.length(); i++) { CallGenerator* cg = _late_inlines.at(i); cg->print_inlining_late("live nodes > LiveNodeCountInliningCutoff"); } Unique_Node_List useful; useful.push(root()); for (uint next = 0; next < useful.size(); ++next) { Node* n = useful.at(next); if (n->is_Call() && n->as_Call()->generator() != NULL && n->as_Call()->generator()->call_node() == n) { CallNode* call = n->as_Call(); CallGenerator* cg = call->generator(); cg->print_inlining_late("receiver not constant"); } uint max = n->len(); for ( uint i = 0; i < max; ++i ) { Node *m = n->in(i); if ( m == NULL ) continue; useful.push(m); } } for (int i = 0; i < _print_inlining_list->length(); i++) { tty->print(_print_inlining_list->at(i).ss()->as_string()); } } } int Compile::cmp_expensive_nodes(Node* n1, Node* n2) { if (n1->Opcode() < n2->Opcode()) return -1; else if (n1->Opcode() > n2->Opcode()) return 1; assert(n1->req() == n2->req(), err_msg_res("can't compare %s nodes: n1->req() = %d, n2->req() = %d", NodeClassNames[n1->Opcode()], n1->req(), n2->req())); for (uint i = 1; i < n1->req(); i++) { if (n1->in(i) < n2->in(i)) return -1; else if (n1->in(i) > n2->in(i)) return 1; } return 0; } int Compile::cmp_expensive_nodes(Node** n1p, Node** n2p) { Node* n1 = *n1p; Node* n2 = *n2p; return cmp_expensive_nodes(n1, n2); } void Compile::sort_expensive_nodes() { if (!expensive_nodes_sorted()) { _expensive_nodes->sort(cmp_expensive_nodes); } } bool Compile::expensive_nodes_sorted() const { for (int i = 1; i < _expensive_nodes->length(); i++) { if (cmp_expensive_nodes(_expensive_nodes->adr_at(i), _expensive_nodes->adr_at(i-1)) < 0) { return false; } } return true; } bool Compile::should_optimize_expensive_nodes(PhaseIterGVN &igvn) { if (_expensive_nodes->length() == 0) { return false; } assert(OptimizeExpensiveOps, "optimization off?"); // Take this opportunity to remove dead nodes from the list int j = 0; for (int i = 0; i < _expensive_nodes->length(); i++) { Node* n = _expensive_nodes->at(i); if (!n->is_unreachable(igvn)) { assert(n->is_expensive(), "should be expensive"); _expensive_nodes->at_put(j, n); j++; } } _expensive_nodes->trunc_to(j); // Then sort the list so that similar nodes are next to each other // and check for at least two nodes of identical kind with same data // inputs. sort_expensive_nodes(); for (int i = 0; i < _expensive_nodes->length()-1; i++) { if (cmp_expensive_nodes(_expensive_nodes->adr_at(i), _expensive_nodes->adr_at(i+1)) == 0) { return true; } } return false; } void Compile::cleanup_expensive_nodes(PhaseIterGVN &igvn) { if (_expensive_nodes->length() == 0) { return; } assert(OptimizeExpensiveOps, "optimization off?"); // Sort to bring similar nodes next to each other and clear the // control input of nodes for which there's only a single copy. sort_expensive_nodes(); int j = 0; int identical = 0; int i = 0; for (; i < _expensive_nodes->length()-1; i++) { assert(j <= i, "can't write beyond current index"); if (_expensive_nodes->at(i)->Opcode() == _expensive_nodes->at(i+1)->Opcode()) { identical++; _expensive_nodes->at_put(j++, _expensive_nodes->at(i)); continue; } if (identical > 0) { _expensive_nodes->at_put(j++, _expensive_nodes->at(i)); identical = 0; } else { Node* n = _expensive_nodes->at(i); igvn.hash_delete(n); n->set_req(0, NULL); igvn.hash_insert(n); } } if (identical > 0) { _expensive_nodes->at_put(j++, _expensive_nodes->at(i)); } else if (_expensive_nodes->length() >= 1) { Node* n = _expensive_nodes->at(i); igvn.hash_delete(n); n->set_req(0, NULL); igvn.hash_insert(n); } _expensive_nodes->trunc_to(j); } void Compile::add_expensive_node(Node * n) { assert(!_expensive_nodes->contains(n), "duplicate entry in expensive list"); assert(n->is_expensive(), "expensive nodes with non-null control here only"); assert(!n->is_CFG() && !n->is_Mem(), "no cfg or memory nodes here"); if (OptimizeExpensiveOps) { _expensive_nodes->append(n); } else { // Clear control input and let IGVN optimize expensive nodes if // OptimizeExpensiveOps is off. n->set_req(0, NULL); } } // Auxiliary method to support randomized stressing/fuzzing. // // This method can be called the arbitrary number of times, with current count // as the argument. The logic allows selecting a single candidate from the // running list of candidates as follows: // int count = 0; // Cand* selected = null; // while(cand = cand->next()) { // if (randomized_select(++count)) { // selected = cand; // } // } // // Including count equalizes the chances any candidate is "selected". // This is useful when we don't have the complete list of candidates to choose // from uniformly. In this case, we need to adjust the randomicity of the // selection, or else we will end up biasing the selection towards the latter // candidates. // // Quick back-envelope calculation shows that for the list of n candidates // the equal probability for the candidate to persist as "best" can be // achieved by replacing it with "next" k-th candidate with the probability // of 1/k. It can be easily shown that by the end of the run, the // probability for any candidate is converged to 1/n, thus giving the // uniform distribution among all the candidates. // // We don't care about the domain size as long as (RANDOMIZED_DOMAIN / count) is large. #define RANDOMIZED_DOMAIN_POW 29 #define RANDOMIZED_DOMAIN (1 << RANDOMIZED_DOMAIN_POW) #define RANDOMIZED_DOMAIN_MASK ((1 << (RANDOMIZED_DOMAIN_POW + 1)) - 1) bool Compile::randomized_select(int count) { assert(count > 0, "only positive"); return (os::random() & RANDOMIZED_DOMAIN_MASK) < (RANDOMIZED_DOMAIN / count); }