jdk8-mips64-public/hotspot: src/share/vm/opto/output.cpp@a433eb716ce1 (annotated)

src/share/vm/opto/output.cpp@a433eb716ce1 (annotated)

src/share/vm/opto/output.cpp

Tue, 25 Mar 2014 12:54:21 -0700

author: goetz
date: Tue, 25 Mar 2014 12:54:21 -0700
changeset 6517: a433eb716ce1
parent 6513: bbfbe9b06038
child 6620: 17b2fbdb6637
permissions: -rw-r--r--

8037821: Account for trampoline stubs when estimating code buffer sizes
Summary: Take into account space needed for "trampoline code" used by calls on PPC64.
Reviewed-by: kvn
Contributed-by: lutz.schmidt@sap.com

 /*
  * Copyright (c) 1998, 2013, 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/assembler.inline.hpp"
 #include "code/compiledIC.hpp"
 #include "code/debugInfo.hpp"
 #include "code/debugInfoRec.hpp"
 #include "compiler/compileBroker.hpp"
 #include "compiler/oopMap.hpp"
 #include "memory/allocation.inline.hpp"
 #include "opto/callnode.hpp"
 #include "opto/cfgnode.hpp"
 #include "opto/locknode.hpp"
 #include "opto/machnode.hpp"
 #include "opto/output.hpp"
 #include "opto/regalloc.hpp"
 #include "opto/runtime.hpp"
 #include "opto/subnode.hpp"
 #include "opto/type.hpp"
 #include "runtime/handles.inline.hpp"
 #include "utilities/xmlstream.hpp"
 #ifndef PRODUCT
 #define DEBUG_ARG(x) , x
 #else
 #define DEBUG_ARG(x)
 #endif
 // Convert Nodes to instruction bits and pass off to the VM
 void Compile::Output() {
   // RootNode goes
   assert( _cfg->get_root_block()->number_of_nodes() == 0, "" );
   // The number of new nodes (mostly MachNop) is proportional to
   // the number of java calls and inner loops which are aligned.
   if ( C->check_node_count((NodeLimitFudgeFactor + C->java_calls()*3 +
                             C->inner_loops()*(OptoLoopAlignment-1)),
                            "out of nodes before code generation" ) ) {
     return;
   }
   // Make sure I can find the Start Node
   Block *entry = _cfg->get_block(1);
   Block *broot = _cfg->get_root_block();
   const StartNode *start = entry->head()->as_Start();
   // Replace StartNode with prolog
   MachPrologNode *prolog = new (this) MachPrologNode();
   entry->map_node(prolog, 0);
   _cfg->map_node_to_block(prolog, entry);
   _cfg->unmap_node_from_block(start); // start is no longer in any block
   // Virtual methods need an unverified entry point
   if( is_osr_compilation() ) {
     if( PoisonOSREntry ) {
       // TODO: Should use a ShouldNotReachHereNode...
       _cfg->insert( broot, 0, new (this) MachBreakpointNode() );
     }
   } else {
     if( _method && !_method->flags().is_static() ) {
       // Insert unvalidated entry point
       _cfg->insert( broot, 0, new (this) MachUEPNode() );
     }
   }
   // Break before main entry point
   if( (_method && _method->break_at_execute())
 #ifndef PRODUCT
     ||(OptoBreakpoint && is_method_compilation())
     ||(OptoBreakpointOSR && is_osr_compilation())
     ||(OptoBreakpointC2R && !_method)
 #endif
     ) {
     // checking for _method means that OptoBreakpoint does not apply to
     // runtime stubs or frame converters
     _cfg->insert( entry, 1, new (this) MachBreakpointNode() );
   }
   // Insert epilogs before every return
   for (uint i = 0; i < _cfg->number_of_blocks(); i++) {
     Block* block = _cfg->get_block(i);
     if (!block->is_connector() && block->non_connector_successor(0) == _cfg->get_root_block()) { // Found a program exit point?
       Node* m = block->end();
       if (m->is_Mach() && m->as_Mach()->ideal_Opcode() != Op_Halt) {
         MachEpilogNode* epilog = new (this) MachEpilogNode(m->as_Mach()->ideal_Opcode() == Op_Return);
         block->add_inst(epilog);
         _cfg->map_node_to_block(epilog, block);
       }
     }
   }
 # ifdef ENABLE_ZAP_DEAD_LOCALS
   if (ZapDeadCompiledLocals) {
     Insert_zap_nodes();
   }
 # endif
   uint* blk_starts = NEW_RESOURCE_ARRAY(uint, _cfg->number_of_blocks() + 1);
   blk_starts[0] = 0;
   // Initialize code buffer and process short branches.
   CodeBuffer* cb = init_buffer(blk_starts);
   if (cb == NULL || failing()) {
     return;
   }
   ScheduleAndBundle();
 #ifndef PRODUCT
   if (trace_opto_output()) {
     tty->print("\n---- After ScheduleAndBundle ----\n");
     for (uint i = 0; i < _cfg->number_of_blocks(); i++) {
       tty->print("\nBB#%03d:\n", i);
       Block* block = _cfg->get_block(i);
       for (uint j = 0; j < block->number_of_nodes(); j++) {
         Node* n = block->get_node(j);
         OptoReg::Name reg = _regalloc->get_reg_first(n);
         tty->print(" %-6s ", reg >= 0 && reg < REG_COUNT ? Matcher::regName[reg] : "");
         n->dump();
       }
     }
   }
 #endif
   if (failing()) {
     return;
   }
   BuildOopMaps();
   if (failing())  {
     return;
   }
   fill_buffer(cb, blk_starts);
 }
 bool Compile::need_stack_bang(int frame_size_in_bytes) const {
   // Determine if we need to generate a stack overflow check.
   // Do it if the method is not a stub function and
   // has java calls or has frame size > vm_page_size/8.
   return (UseStackBanging && stub_function() == NULL &&
           (has_java_calls() || frame_size_in_bytes > os::vm_page_size()>>3));
 }
 bool Compile::need_register_stack_bang() const {
   // Determine if we need to generate a register stack overflow check.
   // This is only used on architectures which have split register
   // and memory stacks (ie. IA64).
   // Bang if the method is not a stub function and has java calls
   return (stub_function() == NULL && has_java_calls());
 }
 # ifdef ENABLE_ZAP_DEAD_LOCALS
 // In order to catch compiler oop-map bugs, we have implemented
 // a debugging mode called ZapDeadCompilerLocals.
 // This mode causes the compiler to insert a call to a runtime routine,
 // "zap_dead_locals", right before each place in compiled code
 // that could potentially be a gc-point (i.e., a safepoint or oop map point).
 // The runtime routine checks that locations mapped as oops are really
 // oops, that locations mapped as values do not look like oops,
 // and that locations mapped as dead are not used later
 // (by zapping them to an invalid address).
 int Compile::_CompiledZap_count = 0;
 void Compile::Insert_zap_nodes() {
   bool skip = false;
   // Dink with static counts because code code without the extra
   // runtime calls is MUCH faster for debugging purposes
        if ( CompileZapFirst  ==  0  ) ; // nothing special
   else if ( CompileZapFirst  >  CompiledZap_count() )  skip = true;
   else if ( CompileZapFirst  == CompiledZap_count() )
     warning("starting zap compilation after skipping");
        if ( CompileZapLast  ==  -1  ) ; // nothing special
   else if ( CompileZapLast  <   CompiledZap_count() )  skip = true;
   else if ( CompileZapLast  ==  CompiledZap_count() )
     warning("about to compile last zap");
   ++_CompiledZap_count; // counts skipped zaps, too
   if ( skip )  return;
   if ( _method == NULL )
     return; // no safepoints/oopmaps emitted for calls in stubs,so we don't care
   // Insert call to zap runtime stub before every node with an oop map
   for( uint i=0; i<_cfg->number_of_blocks(); i++ ) {
     Block *b = _cfg->get_block(i);
     for ( uint j = 0;  j < b->number_of_nodes();  ++j ) {
       Node *n = b->get_node(j);
       // Determining if we should insert a zap-a-lot node in output.
       // We do that for all nodes that has oopmap info, except for calls
       // to allocation.  Calls to allocation passes in the old top-of-eden pointer
       // and expect the C code to reset it.  Hence, there can be no safepoints between
       // the inlined-allocation and the call to new_Java, etc.
       // We also cannot zap monitor calls, as they must hold the microlock
       // during the call to Zap, which also wants to grab the microlock.
       bool insert = n->is_MachSafePoint() && (n->as_MachSafePoint()->oop_map() != NULL);
       if ( insert ) { // it is MachSafePoint
         if ( !n->is_MachCall() ) {
           insert = false;
         } else if ( n->is_MachCall() ) {
           MachCallNode* call = n->as_MachCall();
           if (call->entry_point() == OptoRuntime::new_instance_Java() ||
               call->entry_point() == OptoRuntime::new_array_Java() ||
               call->entry_point() == OptoRuntime::multianewarray2_Java() ||
               call->entry_point() == OptoRuntime::multianewarray3_Java() ||
               call->entry_point() == OptoRuntime::multianewarray4_Java() ||
               call->entry_point() == OptoRuntime::multianewarray5_Java() ||
               call->entry_point() == OptoRuntime::slow_arraycopy_Java() ||
               call->entry_point() == OptoRuntime::complete_monitor_locking_Java()
               ) {
             insert = false;
           }
         }
         if (insert) {
           Node *zap = call_zap_node(n->as_MachSafePoint(), i);
           b->insert_node(zap, j);
           _cfg->map_node_to_block(zap, b);
           ++j;
         }
       }
     }
   }
 }
 Node* Compile::call_zap_node(MachSafePointNode* node_to_check, int block_no) {
   const TypeFunc *tf = OptoRuntime::zap_dead_locals_Type();
   CallStaticJavaNode* ideal_node =
     new (this) CallStaticJavaNode( tf,
          OptoRuntime::zap_dead_locals_stub(_method->flags().is_native()),
                        "call zap dead locals stub", 0, TypePtr::BOTTOM);
   // We need to copy the OopMap from the site we're zapping at.
   // We have to make a copy, because the zap site might not be
   // a call site, and zap_dead is a call site.
   OopMap* clone = node_to_check->oop_map()->deep_copy();
   // Add the cloned OopMap to the zap node
   ideal_node->set_oop_map(clone);
   return _matcher->match_sfpt(ideal_node);
 }
 bool Compile::is_node_getting_a_safepoint( Node* n) {
   // This code duplicates the logic prior to the call of add_safepoint
   // below in this file.
   if( n->is_MachSafePoint() ) return true;
   return false;
 }
 # endif // ENABLE_ZAP_DEAD_LOCALS
 // Compute the size of first NumberOfLoopInstrToAlign instructions at the top
 // of a loop. When aligning a loop we need to provide enough instructions
 // in cpu's fetch buffer to feed decoders. The loop alignment could be
 // avoided if we have enough instructions in fetch buffer at the head of a loop.
 // By default, the size is set to 999999 by Block's constructor so that
 // a loop will be aligned if the size is not reset here.
 //
 // Note: Mach instructions could contain several HW instructions
 // so the size is estimated only.
 //
 void Compile::compute_loop_first_inst_sizes() {
   // The next condition is used to gate the loop alignment optimization.
   // Don't aligned a loop if there are enough instructions at the head of a loop
   // or alignment padding is larger then MaxLoopPad. By default, MaxLoopPad
   // is equal to OptoLoopAlignment-1 except on new Intel cpus, where it is
   // equal to 11 bytes which is the largest address NOP instruction.
   if (MaxLoopPad < OptoLoopAlignment - 1) {
     uint last_block = _cfg->number_of_blocks() - 1;
     for (uint i = 1; i <= last_block; i++) {
       Block* block = _cfg->get_block(i);
       // Check the first loop's block which requires an alignment.
       if (block->loop_alignment() > (uint)relocInfo::addr_unit()) {
         uint sum_size = 0;
         uint inst_cnt = NumberOfLoopInstrToAlign;
         inst_cnt = block->compute_first_inst_size(sum_size, inst_cnt, _regalloc);
         // Check subsequent fallthrough blocks if the loop's first
         // block(s) does not have enough instructions.
         Block *nb = block;
         while(inst_cnt > 0 &&
               i < last_block &&
               !_cfg->get_block(i + 1)->has_loop_alignment() &&
               !nb->has_successor(block)) {
           i++;
           nb = _cfg->get_block(i);
           inst_cnt  = nb->compute_first_inst_size(sum_size, inst_cnt, _regalloc);
         } // while( inst_cnt > 0 && i < last_block  )
         block->set_first_inst_size(sum_size);
       } // f( b->head()->is_Loop() )
     } // for( i <= last_block )
   } // if( MaxLoopPad < OptoLoopAlignment-1 )
 }
 // The architecture description provides short branch variants for some long
 // branch instructions. Replace eligible long branches with short branches.
 void Compile::shorten_branches(uint* blk_starts, int& code_size, int& reloc_size, int& stub_size) {
   // Compute size of each block, method size, and relocation information size
   uint nblocks  = _cfg->number_of_blocks();
   uint*      jmp_offset = NEW_RESOURCE_ARRAY(uint,nblocks);
   uint*      jmp_size   = NEW_RESOURCE_ARRAY(uint,nblocks);
   int*       jmp_nidx   = NEW_RESOURCE_ARRAY(int ,nblocks);
   // Collect worst case block paddings
   int* block_worst_case_pad = NEW_RESOURCE_ARRAY(int, nblocks);
   memset(block_worst_case_pad, 0, nblocks * sizeof(int));
   DEBUG_ONLY( uint *jmp_target = NEW_RESOURCE_ARRAY(uint,nblocks); )
   DEBUG_ONLY( uint *jmp_rule = NEW_RESOURCE_ARRAY(uint,nblocks); )
   bool has_short_branch_candidate = false;
   // Initialize the sizes to 0
   code_size  = 0;          // Size in bytes of generated code
   stub_size  = 0;          // Size in bytes of all stub entries
   // Size in bytes of all relocation entries, including those in local stubs.
   // Start with 2-bytes of reloc info for the unvalidated entry point
   reloc_size = 1;          // Number of relocation entries
   // Make three passes.  The first computes pessimistic blk_starts,
   // relative jmp_offset and reloc_size information.  The second performs
   // short branch substitution using the pessimistic sizing.  The
   // third inserts nops where needed.
   // Step one, perform a pessimistic sizing pass.
   uint last_call_adr = max_uint;
   uint last_avoid_back_to_back_adr = max_uint;
   uint nop_size = (new (this) MachNopNode())->size(_regalloc);
   for (uint i = 0; i < nblocks; i++) { // For all blocks
     Block* block = _cfg->get_block(i);
     // During short branch replacement, we store the relative (to blk_starts)
     // offset of jump in jmp_offset, rather than the absolute offset of jump.
     // This is so that we do not need to recompute sizes of all nodes when
     // we compute correct blk_starts in our next sizing pass.
     jmp_offset[i] = 0;
     jmp_size[i]   = 0;
     jmp_nidx[i]   = -1;
     DEBUG_ONLY( jmp_target[i] = 0; )
     DEBUG_ONLY( jmp_rule[i]   = 0; )
     // Sum all instruction sizes to compute block size
     uint last_inst = block->number_of_nodes();
     uint blk_size = 0;
     for (uint j = 0; j < last_inst; j++) {
       Node* nj = block->get_node(j);
       // Handle machine instruction nodes
       if (nj->is_Mach()) {
         MachNode *mach = nj->as_Mach();
         blk_size += (mach->alignment_required() - 1) * relocInfo::addr_unit(); // assume worst case padding
         reloc_size += mach->reloc();
         if (mach->is_MachCall()) {
           // add size information for trampoline stub
           // class CallStubImpl is platform-specific and defined in the *.ad files.
           stub_size  += CallStubImpl::size_call_trampoline();
           reloc_size += CallStubImpl::reloc_call_trampoline();
           MachCallNode *mcall = mach->as_MachCall();
           // This destination address is NOT PC-relative
           mcall->method_set((intptr_t)mcall->entry_point());
           if (mcall->is_MachCallJava() && mcall->as_MachCallJava()->_method) {
             stub_size  += CompiledStaticCall::to_interp_stub_size();
             reloc_size += CompiledStaticCall::reloc_to_interp_stub();
           }
         } else if (mach->is_MachSafePoint()) {
           // If call/safepoint are adjacent, account for possible
           // nop to disambiguate the two safepoints.
           // ScheduleAndBundle() can rearrange nodes in a block,
           // check for all offsets inside this block.
           if (last_call_adr >= blk_starts[i]) {
             blk_size += nop_size;
           }
         }
         if (mach->avoid_back_to_back()) {
           // Nop is inserted between "avoid back to back" instructions.
           // ScheduleAndBundle() can rearrange nodes in a block,
           // check for all offsets inside this block.
           if (last_avoid_back_to_back_adr >= blk_starts[i]) {
             blk_size += nop_size;
           }
         }
         if (mach->may_be_short_branch()) {
           if (!nj->is_MachBranch()) {
 #ifndef PRODUCT
             nj->dump(3);
 #endif
             Unimplemented();
           }
           assert(jmp_nidx[i] == -1, "block should have only one branch");
           jmp_offset[i] = blk_size;
           jmp_size[i]   = nj->size(_regalloc);
           jmp_nidx[i]   = j;
           has_short_branch_candidate = true;
         }
       }
       blk_size += nj->size(_regalloc);
       // Remember end of call offset
       if (nj->is_MachCall() && !nj->is_MachCallLeaf()) {
         last_call_adr = blk_starts[i]+blk_size;
       }
       // Remember end of avoid_back_to_back offset
       if (nj->is_Mach() && nj->as_Mach()->avoid_back_to_back()) {
         last_avoid_back_to_back_adr = blk_starts[i]+blk_size;
       }
     }
     // When the next block starts a loop, we may insert pad NOP
     // instructions.  Since we cannot know our future alignment,
     // assume the worst.
     if (i < nblocks - 1) {
       Block* nb = _cfg->get_block(i + 1);
       int max_loop_pad = nb->code_alignment()-relocInfo::addr_unit();
       if (max_loop_pad > 0) {
         assert(is_power_of_2(max_loop_pad+relocInfo::addr_unit()), "");
         // Adjust last_call_adr and/or last_avoid_back_to_back_adr.
         // If either is the last instruction in this block, bump by
         // max_loop_pad in lock-step with blk_size, so sizing
         // calculations in subsequent blocks still can conservatively
         // detect that it may the last instruction in this block.
         if (last_call_adr == blk_starts[i]+blk_size) {
           last_call_adr += max_loop_pad;
         }
         if (last_avoid_back_to_back_adr == blk_starts[i]+blk_size) {
           last_avoid_back_to_back_adr += max_loop_pad;
         }
         blk_size += max_loop_pad;
         block_worst_case_pad[i + 1] = max_loop_pad;
       }
     }
     // Save block size; update total method size
     blk_starts[i+1] = blk_starts[i]+blk_size;
   }
   // Step two, replace eligible long jumps.
   bool progress = true;
   uint last_may_be_short_branch_adr = max_uint;
   while (has_short_branch_candidate && progress) {
     progress = false;
     has_short_branch_candidate = false;
     int adjust_block_start = 0;
     for (uint i = 0; i < nblocks; i++) {
       Block* block = _cfg->get_block(i);
       int idx = jmp_nidx[i];
       MachNode* mach = (idx == -1) ? NULL: block->get_node(idx)->as_Mach();
       if (mach != NULL && mach->may_be_short_branch()) {
 #ifdef ASSERT
         assert(jmp_size[i] > 0 && mach->is_MachBranch(), "sanity");
         int j;
         // Find the branch; ignore trailing NOPs.
         for (j = block->number_of_nodes()-1; j>=0; j--) {
           Node* n = block->get_node(j);
           if (!n->is_Mach() || n->as_Mach()->ideal_Opcode() != Op_Con)
             break;
         }
         assert(j >= 0 && j == idx && block->get_node(j) == (Node*)mach, "sanity");
 #endif
         int br_size = jmp_size[i];
         int br_offs = blk_starts[i] + jmp_offset[i];
         // This requires the TRUE branch target be in succs[0]
         uint bnum = block->non_connector_successor(0)->_pre_order;
         int offset = blk_starts[bnum] - br_offs;
         if (bnum > i) { // adjust following block's offset
           offset -= adjust_block_start;
         }
         // This block can be a loop header, account for the padding
         // in the previous block.
         int block_padding = block_worst_case_pad[i];
         assert(i == 0 || block_padding == 0 || br_offs >= block_padding, "Should have at least a padding on top");
         // In the following code a nop could be inserted before
         // the branch which will increase the backward distance.
         bool needs_padding = ((uint)(br_offs - block_padding) == last_may_be_short_branch_adr);
         assert(!needs_padding || jmp_offset[i] == 0, "padding only branches at the beginning of block");
         if (needs_padding && offset <= 0)
           offset -= nop_size;
         if (_matcher->is_short_branch_offset(mach->rule(), br_size, offset)) {
           // We've got a winner.  Replace this branch.
           MachNode* replacement = mach->as_MachBranch()->short_branch_version(this);
           // Update the jmp_size.
           int new_size = replacement->size(_regalloc);
           int diff     = br_size - new_size;
           assert(diff >= (int)nop_size, "short_branch size should be smaller");
           // Conservatively take into accound padding between
           // avoid_back_to_back branches. Previous branch could be
           // converted into avoid_back_to_back branch during next
           // rounds.
           if (needs_padding && replacement->avoid_back_to_back()) {
             jmp_offset[i] += nop_size;
             diff -= nop_size;
           }
           adjust_block_start += diff;
           block->map_node(replacement, idx);
           mach->subsume_by(replacement, C);
           mach = replacement;
           progress = true;
           jmp_size[i] = new_size;
           DEBUG_ONLY( jmp_target[i] = bnum; );
           DEBUG_ONLY( jmp_rule[i] = mach->rule(); );
         } else {
           // The jump distance is not short, try again during next iteration.
           has_short_branch_candidate = true;
         }
       } // (mach->may_be_short_branch())
       if (mach != NULL && (mach->may_be_short_branch() ||
                            mach->avoid_back_to_back())) {
         last_may_be_short_branch_adr = blk_starts[i] + jmp_offset[i] + jmp_size[i];
       }
       blk_starts[i+1] -= adjust_block_start;
     }
   }
 #ifdef ASSERT
   for (uint i = 0; i < nblocks; i++) { // For all blocks
     if (jmp_target[i] != 0) {
       int br_size = jmp_size[i];
       int offset = blk_starts[jmp_target[i]]-(blk_starts[i] + jmp_offset[i]);
       if (!_matcher->is_short_branch_offset(jmp_rule[i], br_size, offset)) {
         tty->print_cr("target (%d) - jmp_offset(%d) = offset (%d), jump_size(%d), jmp_block B%d, target_block B%d", blk_starts[jmp_target[i]], blk_starts[i] + jmp_offset[i], offset, br_size, i, jmp_target[i]);
       }
       assert(_matcher->is_short_branch_offset(jmp_rule[i], br_size, offset), "Displacement too large for short jmp");
     }
   }
 #endif
   // Step 3, compute the offsets of all blocks, will be done in fill_buffer()
   // after ScheduleAndBundle().
   // ------------------
   // Compute size for code buffer
   code_size = blk_starts[nblocks];
   // Relocation records
   reloc_size += 1;              // Relo entry for exception handler
   // Adjust reloc_size to number of record of relocation info
   // Min is 2 bytes, max is probably 6 or 8, with a tax up to 25% for
   // a relocation index.
   // The CodeBuffer will expand the locs array if this estimate is too low.
   reloc_size *= 10 / sizeof(relocInfo);
 }
 //------------------------------FillLocArray-----------------------------------
 // Create a bit of debug info and append it to the array.  The mapping is from
 // Java local or expression stack to constant, register or stack-slot.  For
 // doubles, insert 2 mappings and return 1 (to tell the caller that the next
 // entry has been taken care of and caller should skip it).
 static LocationValue *new_loc_value( PhaseRegAlloc *ra, OptoReg::Name regnum, Location::Type l_type ) {
   // This should never have accepted Bad before
   assert(OptoReg::is_valid(regnum), "location must be valid");
   return (OptoReg::is_reg(regnum))
     ? new LocationValue(Location::new_reg_loc(l_type, OptoReg::as_VMReg(regnum)) )
     : new LocationValue(Location::new_stk_loc(l_type,  ra->reg2offset(regnum)));
 }
 ObjectValue*
 Compile::sv_for_node_id(GrowableArray<ScopeValue*> *objs, int id) {
   for (int i = 0; i < objs->length(); i++) {
     assert(objs->at(i)->is_object(), "corrupt object cache");
     ObjectValue* sv = (ObjectValue*) objs->at(i);
     if (sv->id() == id) {
       return sv;
     }
   }
   // Otherwise..
   return NULL;
 }
 void Compile::set_sv_for_object_node(GrowableArray<ScopeValue*> *objs,
                                      ObjectValue* sv ) {
   assert(sv_for_node_id(objs, sv->id()) == NULL, "Precondition");
   objs->append(sv);
 }
 void Compile::FillLocArray( int idx, MachSafePointNode* sfpt, Node *local,
                             GrowableArray<ScopeValue*> *array,
                             GrowableArray<ScopeValue*> *objs ) {
   assert( local, "use _top instead of null" );
   if (array->length() != idx) {
     assert(array->length() == idx + 1, "Unexpected array count");
     // Old functionality:
     //   return
     // New functionality:
     //   Assert if the local is not top. In product mode let the new node
     //   override the old entry.
     assert(local == top(), "LocArray collision");
     if (local == top()) {
       return;
     }
     array->pop();
   }
   const Type *t = local->bottom_type();
   // Is it a safepoint scalar object node?
   if (local->is_SafePointScalarObject()) {
     SafePointScalarObjectNode* spobj = local->as_SafePointScalarObject();
     ObjectValue* sv = Compile::sv_for_node_id(objs, spobj->_idx);
     if (sv == NULL) {
       ciKlass* cik = t->is_oopptr()->klass();
       assert(cik->is_instance_klass() ||
              cik->is_array_klass(), "Not supported allocation.");
       sv = new ObjectValue(spobj->_idx,
                            new ConstantOopWriteValue(cik->java_mirror()->constant_encoding()));
       Compile::set_sv_for_object_node(objs, sv);
       uint first_ind = spobj->first_index(sfpt->jvms());
       for (uint i = 0; i < spobj->n_fields(); i++) {
         Node* fld_node = sfpt->in(first_ind+i);
         (void)FillLocArray(sv->field_values()->length(), sfpt, fld_node, sv->field_values(), objs);
       }
     }
     array->append(sv);
     return;
   }
   // Grab the register number for the local
   OptoReg::Name regnum = _regalloc->get_reg_first(local);
   if( OptoReg::is_valid(regnum) ) {// Got a register/stack?
     // Record the double as two float registers.
     // The register mask for such a value always specifies two adjacent
     // float registers, with the lower register number even.
     // Normally, the allocation of high and low words to these registers
     // is irrelevant, because nearly all operations on register pairs
     // (e.g., StoreD) treat them as a single unit.
     // Here, we assume in addition that the words in these two registers
     // stored "naturally" (by operations like StoreD and double stores
     // within the interpreter) such that the lower-numbered register
     // is written to the lower memory address.  This may seem like
     // a machine dependency, but it is not--it is a requirement on
     // the author of the <arch>.ad file to ensure that, for every
     // even/odd double-register pair to which a double may be allocated,
     // the word in the even single-register is stored to the first
     // memory word.  (Note that register numbers are completely
     // arbitrary, and are not tied to any machine-level encodings.)
 #ifdef _LP64
     if( t->base() == Type::DoubleBot || t->base() == Type::DoubleCon ) {
       array->append(new ConstantIntValue(0));
       array->append(new_loc_value( _regalloc, regnum, Location::dbl ));
     } else if ( t->base() == Type::Long ) {
       array->append(new ConstantIntValue(0));
       array->append(new_loc_value( _regalloc, regnum, Location::lng ));
     } else if ( t->base() == Type::RawPtr ) {
       // jsr/ret return address which must be restored into a the full
       // width 64-bit stack slot.
       array->append(new_loc_value( _regalloc, regnum, Location::lng ));
     }
 #else //_LP64
 #ifdef SPARC
     if (t->base() == Type::Long && OptoReg::is_reg(regnum)) {
       // For SPARC we have to swap high and low words for
       // long values stored in a single-register (g0-g7).
       array->append(new_loc_value( _regalloc,              regnum   , Location::normal ));
       array->append(new_loc_value( _regalloc, OptoReg::add(regnum,1), Location::normal ));
     } else
 #endif //SPARC
     if( t->base() == Type::DoubleBot || t->base() == Type::DoubleCon || t->base() == Type::Long ) {
       // Repack the double/long as two jints.
       // The convention the interpreter uses is that the second local
       // holds the first raw word of the native double representation.
       // This is actually reasonable, since locals and stack arrays
       // grow downwards in all implementations.
       // (If, on some machine, the interpreter's Java locals or stack
       // were to grow upwards, the embedded doubles would be word-swapped.)
       array->append(new_loc_value( _regalloc, OptoReg::add(regnum,1), Location::normal ));
       array->append(new_loc_value( _regalloc,              regnum   , Location::normal ));
     }
 #endif //_LP64
     else if( (t->base() == Type::FloatBot || t->base() == Type::FloatCon) &&
                OptoReg::is_reg(regnum) ) {
       array->append(new_loc_value( _regalloc, regnum, Matcher::float_in_double()
                                    ? Location::float_in_dbl : Location::normal ));
     } else if( t->base() == Type::Int && OptoReg::is_reg(regnum) ) {
       array->append(new_loc_value( _regalloc, regnum, Matcher::int_in_long
                                    ? Location::int_in_long : Location::normal ));
     } else if( t->base() == Type::NarrowOop ) {
       array->append(new_loc_value( _regalloc, regnum, Location::narrowoop ));
     } else {
       array->append(new_loc_value( _regalloc, regnum, _regalloc->is_oop(local) ? Location::oop : Location::normal ));
     }
     return;
   }
   // No register.  It must be constant data.
   switch (t->base()) {
   case Type::Half:              // Second half of a double
     ShouldNotReachHere();       // Caller should skip 2nd halves
     break;
   case Type::AnyPtr:
     array->append(new ConstantOopWriteValue(NULL));
     break;
   case Type::AryPtr:
   case Type::InstPtr:          // fall through
     array->append(new ConstantOopWriteValue(t->isa_oopptr()->const_oop()->constant_encoding()));
     break;
   case Type::NarrowOop:
     if (t == TypeNarrowOop::NULL_PTR) {
       array->append(new ConstantOopWriteValue(NULL));
     } else {
       array->append(new ConstantOopWriteValue(t->make_ptr()->isa_oopptr()->const_oop()->constant_encoding()));
     }
     break;
   case Type::Int:
     array->append(new ConstantIntValue(t->is_int()->get_con()));
     break;
   case Type::RawPtr:
     // A return address (T_ADDRESS).
     assert((intptr_t)t->is_ptr()->get_con() < (intptr_t)0x10000, "must be a valid BCI");
 #ifdef _LP64
     // Must be restored to the full-width 64-bit stack slot.
     array->append(new ConstantLongValue(t->is_ptr()->get_con()));
 #else
     array->append(new ConstantIntValue(t->is_ptr()->get_con()));
 #endif
     break;
   case Type::FloatCon: {
     float f = t->is_float_constant()->getf();
     array->append(new ConstantIntValue(jint_cast(f)));
     break;
   }
   case Type::DoubleCon: {
     jdouble d = t->is_double_constant()->getd();
 #ifdef _LP64
     array->append(new ConstantIntValue(0));
     array->append(new ConstantDoubleValue(d));
 #else
     // Repack the double as two jints.
     // The convention the interpreter uses is that the second local
     // holds the first raw word of the native double representation.
     // This is actually reasonable, since locals and stack arrays
     // grow downwards in all implementations.
     // (If, on some machine, the interpreter's Java locals or stack
     // were to grow upwards, the embedded doubles would be word-swapped.)
     jint   *dp = (jint*)&d;
     array->append(new ConstantIntValue(dp[1]));
     array->append(new ConstantIntValue(dp[0]));
 #endif
     break;
   }
   case Type::Long: {
     jlong d = t->is_long()->get_con();
 #ifdef _LP64
     array->append(new ConstantIntValue(0));
     array->append(new ConstantLongValue(d));
 #else
     // Repack the long as two jints.
     // The convention the interpreter uses is that the second local
     // holds the first raw word of the native double representation.
     // This is actually reasonable, since locals and stack arrays
     // grow downwards in all implementations.
     // (If, on some machine, the interpreter's Java locals or stack
     // were to grow upwards, the embedded doubles would be word-swapped.)
     jint *dp = (jint*)&d;
     array->append(new ConstantIntValue(dp[1]));
     array->append(new ConstantIntValue(dp[0]));
 #endif
     break;
   }
   case Type::Top:               // Add an illegal value here
     array->append(new LocationValue(Location()));
     break;
   default:
     ShouldNotReachHere();
     break;
   }
 }
 // Determine if this node starts a bundle
 bool Compile::starts_bundle(const Node *n) const {
   return (_node_bundling_limit > n->_idx &&
           _node_bundling_base[n->_idx].starts_bundle());
 }
 //--------------------------Process_OopMap_Node--------------------------------
 void Compile::Process_OopMap_Node(MachNode *mach, int current_offset) {
   // Handle special safepoint nodes for synchronization
   MachSafePointNode *sfn   = mach->as_MachSafePoint();
   MachCallNode      *mcall;
 #ifdef ENABLE_ZAP_DEAD_LOCALS
   assert( is_node_getting_a_safepoint(mach),  "logic does not match; false negative");
 #endif
   int safepoint_pc_offset = current_offset;
   bool is_method_handle_invoke = false;
   bool return_oop = false;
   // Add the safepoint in the DebugInfoRecorder
   if( !mach->is_MachCall() ) {
     mcall = NULL;
     debug_info()->add_safepoint(safepoint_pc_offset, sfn->_oop_map);
   } else {
     mcall = mach->as_MachCall();
     // Is the call a MethodHandle call?
     if (mcall->is_MachCallJava()) {
       if (mcall->as_MachCallJava()->_method_handle_invoke) {
         assert(has_method_handle_invokes(), "must have been set during call generation");
         is_method_handle_invoke = true;
       }
     }
     // Check if a call returns an object.
     if (mcall->return_value_is_used() &&
         mcall->tf()->range()->field_at(TypeFunc::Parms)->isa_ptr()) {
       return_oop = true;
     }
     safepoint_pc_offset += mcall->ret_addr_offset();
     debug_info()->add_safepoint(safepoint_pc_offset, mcall->_oop_map);
   }
   // Loop over the JVMState list to add scope information
   // Do not skip safepoints with a NULL method, they need monitor info
   JVMState* youngest_jvms = sfn->jvms();
   int max_depth = youngest_jvms->depth();
   // Allocate the object pool for scalar-replaced objects -- the map from
   // small-integer keys (which can be recorded in the local and ostack
   // arrays) to descriptions of the object state.
   GrowableArray<ScopeValue*> *objs = new GrowableArray<ScopeValue*>();
   // Visit scopes from oldest to youngest.
   for (int depth = 1; depth <= max_depth; depth++) {
     JVMState* jvms = youngest_jvms->of_depth(depth);
     int idx;
     ciMethod* method = jvms->has_method() ? jvms->method() : NULL;
     // Safepoints that do not have method() set only provide oop-map and monitor info
     // to support GC; these do not support deoptimization.
     int num_locs = (method == NULL) ? 0 : jvms->loc_size();
     int num_exps = (method == NULL) ? 0 : jvms->stk_size();
     int num_mon  = jvms->nof_monitors();
     assert(method == NULL || jvms->bci() < 0 || num_locs == method->max_locals(),
            "JVMS local count must match that of the method");
     // Add Local and Expression Stack Information
     // Insert locals into the locarray
     GrowableArray<ScopeValue*> *locarray = new GrowableArray<ScopeValue*>(num_locs);
     for( idx = 0; idx < num_locs; idx++ ) {
       FillLocArray( idx, sfn, sfn->local(jvms, idx), locarray, objs );
     }
     // Insert expression stack entries into the exparray
     GrowableArray<ScopeValue*> *exparray = new GrowableArray<ScopeValue*>(num_exps);
     for( idx = 0; idx < num_exps; idx++ ) {
       FillLocArray( idx,  sfn, sfn->stack(jvms, idx), exparray, objs );
     }
     // Add in mappings of the monitors
     assert( !method ||
             !method->is_synchronized() ||
             method->is_native() ||
             num_mon > 0 ||
             !GenerateSynchronizationCode,
             "monitors must always exist for synchronized methods");
     // Build the growable array of ScopeValues for exp stack
     GrowableArray<MonitorValue*> *monarray = new GrowableArray<MonitorValue*>(num_mon);
     // Loop over monitors and insert into array
     for (idx = 0; idx < num_mon; idx++) {
       // Grab the node that defines this monitor
       Node* box_node = sfn->monitor_box(jvms, idx);
       Node* obj_node = sfn->monitor_obj(jvms, idx);
       // Create ScopeValue for object
       ScopeValue *scval = NULL;
       if (obj_node->is_SafePointScalarObject()) {
         SafePointScalarObjectNode* spobj = obj_node->as_SafePointScalarObject();
         scval = Compile::sv_for_node_id(objs, spobj->_idx);
         if (scval == NULL) {
           const Type *t = spobj->bottom_type();
           ciKlass* cik = t->is_oopptr()->klass();
           assert(cik->is_instance_klass() ||
                  cik->is_array_klass(), "Not supported allocation.");
           ObjectValue* sv = new ObjectValue(spobj->_idx,
                                             new ConstantOopWriteValue(cik->java_mirror()->constant_encoding()));
           Compile::set_sv_for_object_node(objs, sv);
           uint first_ind = spobj->first_index(youngest_jvms);
           for (uint i = 0; i < spobj->n_fields(); i++) {
             Node* fld_node = sfn->in(first_ind+i);
             (void)FillLocArray(sv->field_values()->length(), sfn, fld_node, sv->field_values(), objs);
           }
           scval = sv;
         }
       } else if (!obj_node->is_Con()) {
         OptoReg::Name obj_reg = _regalloc->get_reg_first(obj_node);
         if( obj_node->bottom_type()->base() == Type::NarrowOop ) {
           scval = new_loc_value( _regalloc, obj_reg, Location::narrowoop );
         } else {
           scval = new_loc_value( _regalloc, obj_reg, Location::oop );
         }
       } else {
         const TypePtr *tp = obj_node->get_ptr_type();
         scval = new ConstantOopWriteValue(tp->is_oopptr()->const_oop()->constant_encoding());
       }
       OptoReg::Name box_reg = BoxLockNode::reg(box_node);
       Location basic_lock = Location::new_stk_loc(Location::normal,_regalloc->reg2offset(box_reg));
       bool eliminated = (box_node->is_BoxLock() && box_node->as_BoxLock()->is_eliminated());
       monarray->append(new MonitorValue(scval, basic_lock, eliminated));
     }
     // We dump the object pool first, since deoptimization reads it in first.
     debug_info()->dump_object_pool(objs);
     // Build first class objects to pass to scope
     DebugToken *locvals = debug_info()->create_scope_values(locarray);
     DebugToken *expvals = debug_info()->create_scope_values(exparray);
     DebugToken *monvals = debug_info()->create_monitor_values(monarray);
     // Make method available for all Safepoints
     ciMethod* scope_method = method ? method : _method;
     // Describe the scope here
     assert(jvms->bci() >= InvocationEntryBci && jvms->bci() <= 0x10000, "must be a valid or entry BCI");
     assert(!jvms->should_reexecute() || depth == max_depth, "reexecute allowed only for the youngest");
     // Now we can describe the scope.
     debug_info()->describe_scope(safepoint_pc_offset, scope_method, jvms->bci(), jvms->should_reexecute(), is_method_handle_invoke, return_oop, locvals, expvals, monvals);
   } // End jvms loop
   // Mark the end of the scope set.
   debug_info()->end_safepoint(safepoint_pc_offset);
 }
 // A simplified version of Process_OopMap_Node, to handle non-safepoints.
 class NonSafepointEmitter {
   Compile*  C;
   JVMState* _pending_jvms;
   int       _pending_offset;
   void emit_non_safepoint();
  public:
   NonSafepointEmitter(Compile* compile) {
     this->C = compile;
     _pending_jvms = NULL;
     _pending_offset = 0;
   }
   void observe_instruction(Node* n, int pc_offset) {
     if (!C->debug_info()->recording_non_safepoints())  return;
     Node_Notes* nn = C->node_notes_at(n->_idx);
     if (nn == NULL || nn->jvms() == NULL)  return;
     if (_pending_jvms != NULL &&
         _pending_jvms->same_calls_as(nn->jvms())) {
       // Repeated JVMS?  Stretch it up here.
       _pending_offset = pc_offset;
     } else {
       if (_pending_jvms != NULL &&
           _pending_offset < pc_offset) {
         emit_non_safepoint();
       }
       _pending_jvms = NULL;
       if (pc_offset > C->debug_info()->last_pc_offset()) {
         // This is the only way _pending_jvms can become non-NULL:
         _pending_jvms = nn->jvms();
         _pending_offset = pc_offset;
       }
     }
   }
   // Stay out of the way of real safepoints:
   void observe_safepoint(JVMState* jvms, int pc_offset) {
     if (_pending_jvms != NULL &&
         !_pending_jvms->same_calls_as(jvms) &&
         _pending_offset < pc_offset) {
       emit_non_safepoint();
     }
     _pending_jvms = NULL;
   }
   void flush_at_end() {
     if (_pending_jvms != NULL) {
       emit_non_safepoint();
     }
     _pending_jvms = NULL;
   }
 };
 void NonSafepointEmitter::emit_non_safepoint() {
   JVMState* youngest_jvms = _pending_jvms;
   int       pc_offset     = _pending_offset;
   // Clear it now:
   _pending_jvms = NULL;
   DebugInformationRecorder* debug_info = C->debug_info();
   assert(debug_info->recording_non_safepoints(), "sanity");
   debug_info->add_non_safepoint(pc_offset);
   int max_depth = youngest_jvms->depth();
   // Visit scopes from oldest to youngest.
   for (int depth = 1; depth <= max_depth; depth++) {
     JVMState* jvms = youngest_jvms->of_depth(depth);
     ciMethod* method = jvms->has_method() ? jvms->method() : NULL;
     assert(!jvms->should_reexecute() || depth==max_depth, "reexecute allowed only for the youngest");
     debug_info->describe_scope(pc_offset, method, jvms->bci(), jvms->should_reexecute());
   }
   // Mark the end of the scope set.
   debug_info->end_non_safepoint(pc_offset);
 }
 //------------------------------init_buffer------------------------------------
 CodeBuffer* Compile::init_buffer(uint* blk_starts) {
   // Set the initially allocated size
   int  code_req   = initial_code_capacity;
   int  locs_req   = initial_locs_capacity;
   int  stub_req   = TraceJumps ? initial_stub_capacity * 10 : initial_stub_capacity;
   int  const_req  = initial_const_capacity;
   int  pad_req    = NativeCall::instruction_size;
   // The extra spacing after the code is necessary on some platforms.
   // Sometimes we need to patch in a jump after the last instruction,
   // if the nmethod has been deoptimized.  (See 4932387, 4894843.)
   // Compute the byte offset where we can store the deopt pc.
   if (fixed_slots() != 0) {
     _orig_pc_slot_offset_in_bytes = _regalloc->reg2offset(OptoReg::stack2reg(_orig_pc_slot));
   }
   // Compute prolog code size
   _method_size = 0;
   _frame_slots = OptoReg::reg2stack(_matcher->_old_SP)+_regalloc->_framesize;
 #if defined(IA64) && !defined(AIX)
   if (save_argument_registers()) {
     // 4815101: this is a stub with implicit and unknown precision fp args.
     // The usual spill mechanism can only generate stfd's in this case, which
     // doesn't work if the fp reg to spill contains a single-precision denorm.
     // Instead, we hack around the normal spill mechanism using stfspill's and
     // ldffill's in the MachProlog and MachEpilog emit methods.  We allocate
     // space here for the fp arg regs (f8-f15) we're going to thusly spill.
     //
     // If we ever implement 16-byte 'registers' == stack slots, we can
     // get rid of this hack and have SpillCopy generate stfspill/ldffill
     // instead of stfd/stfs/ldfd/ldfs.
     _frame_slots += 8*(16/BytesPerInt);
   }
 #endif
   assert(_frame_slots >= 0 && _frame_slots < 1000000, "sanity check");
   if (has_mach_constant_base_node()) {
     uint add_size = 0;
     // Fill the constant table.
     // Note:  This must happen before shorten_branches.
     for (uint i = 0; i < _cfg->number_of_blocks(); i++) {
       Block* b = _cfg->get_block(i);
       for (uint j = 0; j < b->number_of_nodes(); j++) {
         Node* n = b->get_node(j);
         // If the node is a MachConstantNode evaluate the constant
         // value section.
         if (n->is_MachConstant()) {
           MachConstantNode* machcon = n->as_MachConstant();
           machcon->eval_constant(C);
         } else if (n->is_Mach()) {
           // On Power there are more nodes that issue constants.
           add_size += (n->as_Mach()->ins_num_consts() * 8);
         }
       }
     }
     // Calculate the offsets of the constants and the size of the
     // constant table (including the padding to the next section).
     constant_table().calculate_offsets_and_size();
     const_req = constant_table().size() + add_size;
   }
   // Initialize the space for the BufferBlob used to find and verify
   // instruction size in MachNode::emit_size()
   init_scratch_buffer_blob(const_req);
   if (failing())  return NULL; // Out of memory
   // Pre-compute the length of blocks and replace
   // long branches with short if machine supports it.
   shorten_branches(blk_starts, code_req, locs_req, stub_req);
   // nmethod and CodeBuffer count stubs & constants as part of method's code.
   // class HandlerImpl is platform-specific and defined in the *.ad files.
   int exception_handler_req = HandlerImpl::size_exception_handler() + MAX_stubs_size; // add marginal slop for handler
   int deopt_handler_req     = HandlerImpl::size_deopt_handler()     + MAX_stubs_size; // add marginal slop for handler
   stub_req += MAX_stubs_size;   // ensure per-stub margin
   code_req += MAX_inst_size;    // ensure per-instruction margin
   if (StressCodeBuffers)
     code_req = const_req = stub_req = exception_handler_req = deopt_handler_req = 0x10;  // force expansion
   int total_req =
     const_req +
     code_req +
     pad_req +
     stub_req +
     exception_handler_req +
     deopt_handler_req;               // deopt handler
   if (has_method_handle_invokes())
     total_req += deopt_handler_req;  // deopt MH handler
   CodeBuffer* cb = code_buffer();
   cb->initialize(total_req, locs_req);
   // Have we run out of code space?
   if ((cb->blob() == NULL) || (!CompileBroker::should_compile_new_jobs())) {
     C->record_failure("CodeCache is full");
     return NULL;
   }
   // Configure the code buffer.
   cb->initialize_consts_size(const_req);
   cb->initialize_stubs_size(stub_req);
   cb->initialize_oop_recorder(env()->oop_recorder());
   // fill in the nop array for bundling computations
   MachNode *_nop_list[Bundle::_nop_count];
   Bundle::initialize_nops(_nop_list, this);
   return cb;
 }
 //------------------------------fill_buffer------------------------------------
 void Compile::fill_buffer(CodeBuffer* cb, uint* blk_starts) {
   // blk_starts[] contains offsets calculated during short branches processing,
   // offsets should not be increased during following steps.
   // Compute the size of first NumberOfLoopInstrToAlign instructions at head
   // of a loop. It is used to determine the padding for loop alignment.
   compute_loop_first_inst_sizes();
   // Create oopmap set.
   _oop_map_set = new OopMapSet();
   // !!!!! This preserves old handling of oopmaps for now
   debug_info()->set_oopmaps(_oop_map_set);
   uint nblocks  = _cfg->number_of_blocks();
   // Count and start of implicit null check instructions
   uint inct_cnt = 0;
   uint *inct_starts = NEW_RESOURCE_ARRAY(uint, nblocks+1);
   // Count and start of calls
   uint *call_returns = NEW_RESOURCE_ARRAY(uint, nblocks+1);
   uint  return_offset = 0;
   int nop_size = (new (this) MachNopNode())->size(_regalloc);
   int previous_offset = 0;
   int current_offset  = 0;
   int last_call_offset = -1;
   int last_avoid_back_to_back_offset = -1;
 #ifdef ASSERT
   uint* jmp_target = NEW_RESOURCE_ARRAY(uint,nblocks);
   uint* jmp_offset = NEW_RESOURCE_ARRAY(uint,nblocks);
   uint* jmp_size   = NEW_RESOURCE_ARRAY(uint,nblocks);
   uint* jmp_rule   = NEW_RESOURCE_ARRAY(uint,nblocks);
 #endif
   // Create an array of unused labels, one for each basic block, if printing is enabled
 #ifndef PRODUCT
   int *node_offsets      = NULL;
   uint node_offset_limit = unique();
   if (print_assembly())
     node_offsets         = NEW_RESOURCE_ARRAY(int, node_offset_limit);
 #endif
   NonSafepointEmitter non_safepoints(this);  // emit non-safepoints lazily
   // Emit the constant table.
   if (has_mach_constant_base_node()) {
     constant_table().emit(*cb);
   }
   // Create an array of labels, one for each basic block
   Label *blk_labels = NEW_RESOURCE_ARRAY(Label, nblocks+1);
   for (uint i=0; i <= nblocks; i++) {
     blk_labels[i].init();
   }
   // ------------------
   // Now fill in the code buffer
   Node *delay_slot = NULL;
   for (uint i = 0; i < nblocks; i++) {
     Block* block = _cfg->get_block(i);
     Node* head = block->head();
     // If this block needs to start aligned (i.e, can be reached other
     // than by falling-thru from the previous block), then force the
     // start of a new bundle.
     if (Pipeline::requires_bundling() && starts_bundle(head)) {
       cb->flush_bundle(true);
     }
 #ifdef ASSERT
     if (!block->is_connector()) {
       stringStream st;
       block->dump_head(_cfg, &st);
       MacroAssembler(cb).block_comment(st.as_string());
     }
     jmp_target[i] = 0;
     jmp_offset[i] = 0;
     jmp_size[i]   = 0;
     jmp_rule[i]   = 0;
 #endif
     int blk_offset = current_offset;
     // Define the label at the beginning of the basic block
     MacroAssembler(cb).bind(blk_labels[block->_pre_order]);
     uint last_inst = block->number_of_nodes();
     // Emit block normally, except for last instruction.
     // Emit means "dump code bits into code buffer".
     for (uint j = 0; j<last_inst; j++) {
       // Get the node
       Node* n = block->get_node(j);
       // See if delay slots are supported
       if (valid_bundle_info(n) &&
           node_bundling(n)->used_in_unconditional_delay()) {
         assert(delay_slot == NULL, "no use of delay slot node");
         assert(n->size(_regalloc) == Pipeline::instr_unit_size(), "delay slot instruction wrong size");
         delay_slot = n;
         continue;
       }
       // If this starts a new instruction group, then flush the current one
       // (but allow split bundles)
       if (Pipeline::requires_bundling() && starts_bundle(n))
         cb->flush_bundle(false);
       // The following logic is duplicated in the code ifdeffed for
       // ENABLE_ZAP_DEAD_LOCALS which appears above in this file.  It
       // should be factored out.  Or maybe dispersed to the nodes?
       // Special handling for SafePoint/Call Nodes
       bool is_mcall = false;
       if (n->is_Mach()) {
         MachNode *mach = n->as_Mach();
         is_mcall = n->is_MachCall();
         bool is_sfn = n->is_MachSafePoint();
         // If this requires all previous instructions be flushed, then do so
         if (is_sfn || is_mcall || mach->alignment_required() != 1) {
           cb->flush_bundle(true);
           current_offset = cb->insts_size();
         }
         // A padding may be needed again since a previous instruction
         // could be moved to delay slot.
         // align the instruction if necessary
         int padding = mach->compute_padding(current_offset);
         // Make sure safepoint node for polling is distinct from a call's
         // return by adding a nop if needed.
         if (is_sfn && !is_mcall && padding == 0 && current_offset == last_call_offset) {
           padding = nop_size;
         }
         if (padding == 0 && mach->avoid_back_to_back() &&
             current_offset == last_avoid_back_to_back_offset) {
           // Avoid back to back some instructions.
           padding = nop_size;
         }
         if(padding > 0) {
           assert((padding % nop_size) == 0, "padding is not a multiple of NOP size");
           int nops_cnt = padding / nop_size;
           MachNode *nop = new (this) MachNopNode(nops_cnt);
           block->insert_node(nop, j++);
           last_inst++;
           _cfg->map_node_to_block(nop, block);
           nop->emit(*cb, _regalloc);
           cb->flush_bundle(true);
           current_offset = cb->insts_size();
         }
         // Remember the start of the last call in a basic block
         if (is_mcall) {
           MachCallNode *mcall = mach->as_MachCall();
           // This destination address is NOT PC-relative
           mcall->method_set((intptr_t)mcall->entry_point());
           // Save the return address
           call_returns[block->_pre_order] = current_offset + mcall->ret_addr_offset();
           if (mcall->is_MachCallLeaf()) {
             is_mcall = false;
             is_sfn = false;
           }
         }
         // sfn will be valid whenever mcall is valid now because of inheritance
         if (is_sfn || is_mcall) {
           // Handle special safepoint nodes for synchronization
           if (!is_mcall) {
             MachSafePointNode *sfn = mach->as_MachSafePoint();
             // !!!!! Stubs only need an oopmap right now, so bail out
             if (sfn->jvms()->method() == NULL) {
               // Write the oopmap directly to the code blob??!!
 #             ifdef ENABLE_ZAP_DEAD_LOCALS
               assert( !is_node_getting_a_safepoint(sfn),  "logic does not match; false positive");
 #             endif
               continue;
             }
           } // End synchronization
           non_safepoints.observe_safepoint(mach->as_MachSafePoint()->jvms(),
                                            current_offset);
           Process_OopMap_Node(mach, current_offset);
         } // End if safepoint
         // If this is a null check, then add the start of the previous instruction to the list
         else if( mach->is_MachNullCheck() ) {
           inct_starts[inct_cnt++] = previous_offset;
         }
         // If this is a branch, then fill in the label with the target BB's label
         else if (mach->is_MachBranch()) {
           // This requires the TRUE branch target be in succs[0]
           uint block_num = block->non_connector_successor(0)->_pre_order;
           // Try to replace long branch if delay slot is not used,
           // it is mostly for back branches since forward branch's
           // distance is not updated yet.
           bool delay_slot_is_used = valid_bundle_info(n) &&
                                     node_bundling(n)->use_unconditional_delay();
           if (!delay_slot_is_used && mach->may_be_short_branch()) {
            assert(delay_slot == NULL, "not expecting delay slot node");
            int br_size = n->size(_regalloc);
             int offset = blk_starts[block_num] - current_offset;
             if (block_num >= i) {
               // Current and following block's offset are not
               // finalized yet, adjust distance by the difference
               // between calculated and final offsets of current block.
               offset -= (blk_starts[i] - blk_offset);
             }
             // In the following code a nop could be inserted before
             // the branch which will increase the backward distance.
             bool needs_padding = (current_offset == last_avoid_back_to_back_offset);
             if (needs_padding && offset <= 0)
               offset -= nop_size;
             if (_matcher->is_short_branch_offset(mach->rule(), br_size, offset)) {
               // We've got a winner.  Replace this branch.
               MachNode* replacement = mach->as_MachBranch()->short_branch_version(this);
               // Update the jmp_size.
               int new_size = replacement->size(_regalloc);
               assert((br_size - new_size) >= (int)nop_size, "short_branch size should be smaller");
               // Insert padding between avoid_back_to_back branches.
               if (needs_padding && replacement->avoid_back_to_back()) {
                 MachNode *nop = new (this) MachNopNode();
                 block->insert_node(nop, j++);
                 _cfg->map_node_to_block(nop, block);
                 last_inst++;
                 nop->emit(*cb, _regalloc);
                 cb->flush_bundle(true);
                 current_offset = cb->insts_size();
               }
 #ifdef ASSERT
               jmp_target[i] = block_num;
               jmp_offset[i] = current_offset - blk_offset;
               jmp_size[i]   = new_size;
               jmp_rule[i]   = mach->rule();
 #endif
               block->map_node(replacement, j);
               mach->subsume_by(replacement, C);
               n    = replacement;
               mach = replacement;
             }
           }
           mach->as_MachBranch()->label_set( &blk_labels[block_num], block_num );
         } else if (mach->ideal_Opcode() == Op_Jump) {
           for (uint h = 0; h < block->_num_succs; h++) {
             Block* succs_block = block->_succs[h];
             for (uint j = 1; j < succs_block->num_preds(); j++) {
               Node* jpn = succs_block->pred(j);
               if (jpn->is_JumpProj() && jpn->in(0) == mach) {
                 uint block_num = succs_block->non_connector()->_pre_order;
                 Label *blkLabel = &blk_labels[block_num];
                 mach->add_case_label(jpn->as_JumpProj()->proj_no(), blkLabel);
               }
             }
           }
         }
 #ifdef ASSERT
         // Check that oop-store precedes the card-mark
         else if (mach->ideal_Opcode() == Op_StoreCM) {
           uint storeCM_idx = j;
           int count = 0;
           for (uint prec = mach->req(); prec < mach->len(); prec++) {
             Node *oop_store = mach->in(prec);  // Precedence edge
             if (oop_store == NULL) continue;
             count++;
             uint i4;
             for (i4 = 0; i4 < last_inst; ++i4) {
               if (block->get_node(i4) == oop_store) {
                 break;
               }
             }
             // Note: This test can provide a false failure if other precedence
             // edges have been added to the storeCMNode.
             assert(i4 == last_inst || i4 < storeCM_idx, "CM card-mark executes before oop-store");
           }
           assert(count > 0, "storeCM expects at least one precedence edge");
         }
 #endif
         else if (!n->is_Proj()) {
           // Remember the beginning of the previous instruction, in case
           // it's followed by a flag-kill and a null-check.  Happens on
           // Intel all the time, with add-to-memory kind of opcodes.
           previous_offset = current_offset;
         }
         // Not an else-if!
         // If this is a trap based cmp then add its offset to the list.
         if (mach->is_TrapBasedCheckNode()) {
           inct_starts[inct_cnt++] = current_offset;
         }
       }
       // Verify that there is sufficient space remaining
       cb->insts()->maybe_expand_to_ensure_remaining(MAX_inst_size);
       if ((cb->blob() == NULL) || (!CompileBroker::should_compile_new_jobs())) {
         C->record_failure("CodeCache is full");
         return;
       }
       // Save the offset for the listing
 #ifndef PRODUCT
       if (node_offsets && n->_idx < node_offset_limit)
         node_offsets[n->_idx] = cb->insts_size();
 #endif
       // "Normal" instruction case
       DEBUG_ONLY( uint instr_offset = cb->insts_size(); )
       n->emit(*cb, _regalloc);
       current_offset  = cb->insts_size();
 #ifdef ASSERT
       if (n->size(_regalloc) < (current_offset-instr_offset)) {
         n->dump();
         assert(false, "wrong size of mach node");
       }
 #endif
       non_safepoints.observe_instruction(n, current_offset);
       // mcall is last "call" that can be a safepoint
       // record it so we can see if a poll will directly follow it
       // in which case we'll need a pad to make the PcDesc sites unique
       // see  5010568. This can be slightly inaccurate but conservative
       // in the case that return address is not actually at current_offset.
       // This is a small price to pay.
       if (is_mcall) {
         last_call_offset = current_offset;
       }
       if (n->is_Mach() && n->as_Mach()->avoid_back_to_back()) {
         // Avoid back to back some instructions.
         last_avoid_back_to_back_offset = current_offset;
       }
       // See if this instruction has a delay slot
       if (valid_bundle_info(n) && node_bundling(n)->use_unconditional_delay()) {
         assert(delay_slot != NULL, "expecting delay slot node");
         // Back up 1 instruction
         cb->set_insts_end(cb->insts_end() - Pipeline::instr_unit_size());
         // Save the offset for the listing
 #ifndef PRODUCT
         if (node_offsets && delay_slot->_idx < node_offset_limit)
           node_offsets[delay_slot->_idx] = cb->insts_size();
 #endif
         // Support a SafePoint in the delay slot
         if (delay_slot->is_MachSafePoint()) {
           MachNode *mach = delay_slot->as_Mach();
           // !!!!! Stubs only need an oopmap right now, so bail out
           if (!mach->is_MachCall() && mach->as_MachSafePoint()->jvms()->method() == NULL) {
             // Write the oopmap directly to the code blob??!!
 #           ifdef ENABLE_ZAP_DEAD_LOCALS
             assert( !is_node_getting_a_safepoint(mach),  "logic does not match; false positive");
 #           endif
             delay_slot = NULL;
             continue;
           }
           int adjusted_offset = current_offset - Pipeline::instr_unit_size();
           non_safepoints.observe_safepoint(mach->as_MachSafePoint()->jvms(),
                                            adjusted_offset);
           // Generate an OopMap entry
           Process_OopMap_Node(mach, adjusted_offset);
         }
         // Insert the delay slot instruction
         delay_slot->emit(*cb, _regalloc);
         // Don't reuse it
         delay_slot = NULL;
       }
     } // End for all instructions in block
     // If the next block is the top of a loop, pad this block out to align
     // the loop top a little. Helps prevent pipe stalls at loop back branches.
     if (i < nblocks-1) {
       Block *nb = _cfg->get_block(i + 1);
       int padding = nb->alignment_padding(current_offset);
       if( padding > 0 ) {
         MachNode *nop = new (this) MachNopNode(padding / nop_size);
         block->insert_node(nop, block->number_of_nodes());
         _cfg->map_node_to_block(nop, block);
         nop->emit(*cb, _regalloc);
         current_offset = cb->insts_size();
       }
     }
     // Verify that the distance for generated before forward
     // short branches is still valid.
     guarantee((int)(blk_starts[i+1] - blk_starts[i]) >= (current_offset - blk_offset), "shouldn't increase block size");
     // Save new block start offset
     blk_starts[i] = blk_offset;
   } // End of for all blocks
   blk_starts[nblocks] = current_offset;
   non_safepoints.flush_at_end();
   // Offset too large?
   if (failing())  return;
   // Define a pseudo-label at the end of the code
   MacroAssembler(cb).bind( blk_labels[nblocks] );
   // Compute the size of the first block
   _first_block_size = blk_labels[1].loc_pos() - blk_labels[0].loc_pos();
   assert(cb->insts_size() < 500000, "method is unreasonably large");
 #ifdef ASSERT
   for (uint i = 0; i < nblocks; i++) { // For all blocks
     if (jmp_target[i] != 0) {
       int br_size = jmp_size[i];
       int offset = blk_starts[jmp_target[i]]-(blk_starts[i] + jmp_offset[i]);
       if (!_matcher->is_short_branch_offset(jmp_rule[i], br_size, offset)) {
         tty->print_cr("target (%d) - jmp_offset(%d) = offset (%d), jump_size(%d), jmp_block B%d, target_block B%d", blk_starts[jmp_target[i]], blk_starts[i] + jmp_offset[i], offset, br_size, i, jmp_target[i]);
         assert(false, "Displacement too large for short jmp");
       }
     }
   }
 #endif
 #ifndef PRODUCT
   // Information on the size of the method, without the extraneous code
   Scheduling::increment_method_size(cb->insts_size());
 #endif
   // ------------------
   // Fill in exception table entries.
   FillExceptionTables(inct_cnt, call_returns, inct_starts, blk_labels);
   // Only java methods have exception handlers and deopt handlers
   // class HandlerImpl is platform-specific and defined in the *.ad files.
   if (_method) {
     // Emit the exception handler code.
     _code_offsets.set_value(CodeOffsets::Exceptions, HandlerImpl::emit_exception_handler(*cb));
     // Emit the deopt handler code.
     _code_offsets.set_value(CodeOffsets::Deopt, HandlerImpl::emit_deopt_handler(*cb));
     // Emit the MethodHandle deopt handler code (if required).
     if (has_method_handle_invokes()) {
       // We can use the same code as for the normal deopt handler, we
       // just need a different entry point address.
       _code_offsets.set_value(CodeOffsets::DeoptMH, HandlerImpl::emit_deopt_handler(*cb));
     }
   }
   // One last check for failed CodeBuffer::expand:
   if ((cb->blob() == NULL) || (!CompileBroker::should_compile_new_jobs())) {
     C->record_failure("CodeCache is full");
     return;
   }
 #ifndef PRODUCT
   // Dump the assembly code, including basic-block numbers
   if (print_assembly()) {
     ttyLocker ttyl;  // keep the following output all in one block
     if (!VMThread::should_terminate()) {  // test this under the tty lock
       // 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("opto_assembly compile_id='%d'%s", compile_id(),
                    is_osr_compilation()    ? " compile_kind='osr'" :
                    "");
       }
       if (method() != NULL) {
         method()->print_metadata();
       }
       dump_asm(node_offsets, node_offset_limit);
       if (xtty != NULL) {
         xtty->tail("opto_assembly");
       }
     }
   }
 #endif
 }
 void Compile::FillExceptionTables(uint cnt, uint *call_returns, uint *inct_starts, Label *blk_labels) {
   _inc_table.set_size(cnt);
   uint inct_cnt = 0;
   for (uint i = 0; i < _cfg->number_of_blocks(); i++) {
     Block* block = _cfg->get_block(i);
     Node *n = NULL;
     int j;
     // Find the branch; ignore trailing NOPs.
     for (j = block->number_of_nodes() - 1; j >= 0; j--) {
       n = block->get_node(j);
       if (!n->is_Mach() || n->as_Mach()->ideal_Opcode() != Op_Con) {
         break;
       }
     }
     // If we didn't find anything, continue
     if (j < 0) {
       continue;
     }
     // Compute ExceptionHandlerTable subtable entry and add it
     // (skip empty blocks)
     if (n->is_Catch()) {
       // Get the offset of the return from the call
       uint call_return = call_returns[block->_pre_order];
 #ifdef ASSERT
       assert( call_return > 0, "no call seen for this basic block" );
       while (block->get_node(--j)->is_MachProj()) ;
       assert(block->get_node(j)->is_MachCall(), "CatchProj must follow call");
 #endif
       // last instruction is a CatchNode, find it's CatchProjNodes
       int nof_succs = block->_num_succs;
       // allocate space
       GrowableArray<intptr_t> handler_bcis(nof_succs);
       GrowableArray<intptr_t> handler_pcos(nof_succs);
       // iterate through all successors
       for (int j = 0; j < nof_succs; j++) {
         Block* s = block->_succs[j];
         bool found_p = false;
         for (uint k = 1; k < s->num_preds(); k++) {
           Node* pk = s->pred(k);
           if (pk->is_CatchProj() && pk->in(0) == n) {
             const CatchProjNode* p = pk->as_CatchProj();
             found_p = true;
             // add the corresponding handler bci & pco information
             if (p->_con != CatchProjNode::fall_through_index) {
               // p leads to an exception handler (and is not fall through)
               assert(s == _cfg->get_block(s->_pre_order), "bad numbering");
               // no duplicates, please
               if (!handler_bcis.contains(p->handler_bci())) {
                 uint block_num = s->non_connector()->_pre_order;
                 handler_bcis.append(p->handler_bci());
                 handler_pcos.append(blk_labels[block_num].loc_pos());
               }
             }
           }
         }
         assert(found_p, "no matching predecessor found");
         // Note:  Due to empty block removal, one block may have
         // several CatchProj inputs, from the same Catch.
       }
       // Set the offset of the return from the call
       _handler_table.add_subtable(call_return, &handler_bcis, NULL, &handler_pcos);
       continue;
     }
     // Handle implicit null exception table updates
     if (n->is_MachNullCheck()) {
       uint block_num = block->non_connector_successor(0)->_pre_order;
       _inc_table.append(inct_starts[inct_cnt++], blk_labels[block_num].loc_pos());
       continue;
     }
     // Handle implicit exception table updates: trap instructions.
     if (n->is_Mach() && n->as_Mach()->is_TrapBasedCheckNode()) {
       uint block_num = block->non_connector_successor(0)->_pre_order;
       _inc_table.append(inct_starts[inct_cnt++], blk_labels[block_num].loc_pos());
       continue;
     }
   } // End of for all blocks fill in exception table entries
 }
 // Static Variables
 #ifndef PRODUCT
 uint Scheduling::_total_nop_size = 0;
 uint Scheduling::_total_method_size = 0;
 uint Scheduling::_total_branches = 0;
 uint Scheduling::_total_unconditional_delays = 0;
 uint Scheduling::_total_instructions_per_bundle[Pipeline::_max_instrs_per_cycle+1];
 #endif
 // Initializer for class Scheduling
 Scheduling::Scheduling(Arena *arena, Compile &compile)
   : _arena(arena),
     _cfg(compile.cfg()),
     _regalloc(compile.regalloc()),
     _reg_node(arena),
     _bundle_instr_count(0),
     _bundle_cycle_number(0),
     _scheduled(arena),
     _available(arena),
     _next_node(NULL),
     _bundle_use(0, 0, resource_count, &_bundle_use_elements[0]),
     _pinch_free_list(arena)
 #ifndef PRODUCT
   , _branches(0)
   , _unconditional_delays(0)
 #endif
 {
   // Create a MachNopNode
   _nop = new (&compile) MachNopNode();
   // Now that the nops are in the array, save the count
   // (but allow entries for the nops)
   _node_bundling_limit = compile.unique();
   uint node_max = _regalloc->node_regs_max_index();
   compile.set_node_bundling_limit(_node_bundling_limit);
   // This one is persistent within the Compile class
   _node_bundling_base = NEW_ARENA_ARRAY(compile.comp_arena(), Bundle, node_max);
   // Allocate space for fixed-size arrays
   _node_latency    = NEW_ARENA_ARRAY(arena, unsigned short, node_max);
   _uses            = NEW_ARENA_ARRAY(arena, short,          node_max);
   _current_latency = NEW_ARENA_ARRAY(arena, unsigned short, node_max);
   // Clear the arrays
   memset(_node_bundling_base, 0, node_max * sizeof(Bundle));
   memset(_node_latency,       0, node_max * sizeof(unsigned short));
   memset(_uses,               0, node_max * sizeof(short));
   memset(_current_latency,    0, node_max * sizeof(unsigned short));
   // Clear the bundling information
   memcpy(_bundle_use_elements, Pipeline_Use::elaborated_elements, sizeof(Pipeline_Use::elaborated_elements));
   // Get the last node
   Block* block = _cfg->get_block(_cfg->number_of_blocks() - 1);
   _next_node = block->get_node(block->number_of_nodes() - 1);
 }
 #ifndef PRODUCT
 // Scheduling destructor
 Scheduling::~Scheduling() {
   _total_branches             += _branches;
   _total_unconditional_delays += _unconditional_delays;
 }
 #endif
 // Step ahead "i" cycles
 void Scheduling::step(uint i) {
   Bundle *bundle = node_bundling(_next_node);
   bundle->set_starts_bundle();
   // Update the bundle record, but leave the flags information alone
   if (_bundle_instr_count > 0) {
     bundle->set_instr_count(_bundle_instr_count);
     bundle->set_resources_used(_bundle_use.resourcesUsed());
   }
   // Update the state information
   _bundle_instr_count = 0;
   _bundle_cycle_number += i;
   _bundle_use.step(i);
 }
 void Scheduling::step_and_clear() {
   Bundle *bundle = node_bundling(_next_node);
   bundle->set_starts_bundle();
   // Update the bundle record
   if (_bundle_instr_count > 0) {
     bundle->set_instr_count(_bundle_instr_count);
     bundle->set_resources_used(_bundle_use.resourcesUsed());
     _bundle_cycle_number += 1;
   }
   // Clear the bundling information
   _bundle_instr_count = 0;
   _bundle_use.reset();
   memcpy(_bundle_use_elements,
     Pipeline_Use::elaborated_elements,
     sizeof(Pipeline_Use::elaborated_elements));
 }
 // Perform instruction scheduling and bundling over the sequence of
 // instructions in backwards order.
 void Compile::ScheduleAndBundle() {
   // Don't optimize this if it isn't a method
   if (!_method)
     return;
   // Don't optimize this if scheduling is disabled
   if (!do_scheduling())
     return;
   // Scheduling code works only with pairs (8 bytes) maximum.
   if (max_vector_size() > 8)
     return;
   NOT_PRODUCT( TracePhase t2("isched", &_t_instrSched, TimeCompiler); )
   // Create a data structure for all the scheduling information
   Scheduling scheduling(Thread::current()->resource_area(), *this);
   // Walk backwards over each basic block, computing the needed alignment
   // Walk over all the basic blocks
   scheduling.DoScheduling();
 }
 // Compute the latency of all the instructions.  This is fairly simple,
 // because we already have a legal ordering.  Walk over the instructions
 // from first to last, and compute the latency of the instruction based
 // on the latency of the preceding instruction(s).
 void Scheduling::ComputeLocalLatenciesForward(const Block *bb) {
 #ifndef PRODUCT
   if (_cfg->C->trace_opto_output())
     tty->print("# -> ComputeLocalLatenciesForward\n");
 #endif
   // Walk over all the schedulable instructions
   for( uint j=_bb_start; j < _bb_end; j++ ) {
     // This is a kludge, forcing all latency calculations to start at 1.
     // Used to allow latency 0 to force an instruction to the beginning
     // of the bb
     uint latency = 1;
     Node *use = bb->get_node(j);
     uint nlen = use->len();
     // Walk over all the inputs
     for ( uint k=0; k < nlen; k++ ) {
       Node *def = use->in(k);
       if (!def)
         continue;
       uint l = _node_latency[def->_idx] + use->latency(k);
       if (latency < l)
         latency = l;
     }
     _node_latency[use->_idx] = latency;
 #ifndef PRODUCT
     if (_cfg->C->trace_opto_output()) {
       tty->print("# latency %4d: ", latency);
       use->dump();
     }
 #endif
   }
 #ifndef PRODUCT
   if (_cfg->C->trace_opto_output())
     tty->print("# <- ComputeLocalLatenciesForward\n");
 #endif
 } // end ComputeLocalLatenciesForward
 // See if this node fits into the present instruction bundle
 bool Scheduling::NodeFitsInBundle(Node *n) {
   uint n_idx = n->_idx;
   // If this is the unconditional delay instruction, then it fits
   if (n == _unconditional_delay_slot) {
 #ifndef PRODUCT
     if (_cfg->C->trace_opto_output())
       tty->print("#     NodeFitsInBundle [%4d]: TRUE; is in unconditional delay slot\n", n->_idx);
 #endif
     return (true);
   }
   // If the node cannot be scheduled this cycle, skip it
   if (_current_latency[n_idx] > _bundle_cycle_number) {
 #ifndef PRODUCT
     if (_cfg->C->trace_opto_output())
       tty->print("#     NodeFitsInBundle [%4d]: FALSE; latency %4d > %d\n",
         n->_idx, _current_latency[n_idx], _bundle_cycle_number);
 #endif
     return (false);
   }
   const Pipeline *node_pipeline = n->pipeline();
   uint instruction_count = node_pipeline->instructionCount();
   if (node_pipeline->mayHaveNoCode() && n->size(_regalloc) == 0)
     instruction_count = 0;
   else if (node_pipeline->hasBranchDelay() && !_unconditional_delay_slot)
     instruction_count++;
   if (_bundle_instr_count + instruction_count > Pipeline::_max_instrs_per_cycle) {
 #ifndef PRODUCT
     if (_cfg->C->trace_opto_output())
       tty->print("#     NodeFitsInBundle [%4d]: FALSE; too many instructions: %d > %d\n",
         n->_idx, _bundle_instr_count + instruction_count, Pipeline::_max_instrs_per_cycle);
 #endif
     return (false);
   }
   // Don't allow non-machine nodes to be handled this way
   if (!n->is_Mach() && instruction_count == 0)
     return (false);
   // See if there is any overlap
   uint delay = _bundle_use.full_latency(0, node_pipeline->resourceUse());
   if (delay > 0) {
 #ifndef PRODUCT
     if (_cfg->C->trace_opto_output())
       tty->print("#     NodeFitsInBundle [%4d]: FALSE; functional units overlap\n", n_idx);
 #endif
     return false;
   }
 #ifndef PRODUCT
   if (_cfg->C->trace_opto_output())
     tty->print("#     NodeFitsInBundle [%4d]:  TRUE\n", n_idx);
 #endif
   return true;
 }
 Node * Scheduling::ChooseNodeToBundle() {
   uint siz = _available.size();
   if (siz == 0) {
 #ifndef PRODUCT
     if (_cfg->C->trace_opto_output())
       tty->print("#   ChooseNodeToBundle: NULL\n");
 #endif
     return (NULL);
   }
   // Fast path, if only 1 instruction in the bundle
   if (siz == 1) {
 #ifndef PRODUCT
     if (_cfg->C->trace_opto_output()) {
       tty->print("#   ChooseNodeToBundle (only 1): ");
       _available[0]->dump();
     }
 #endif
     return (_available[0]);
   }
   // Don't bother, if the bundle is already full
   if (_bundle_instr_count < Pipeline::_max_instrs_per_cycle) {
     for ( uint i = 0; i < siz; i++ ) {
       Node *n = _available[i];
       // Skip projections, we'll handle them another way
       if (n->is_Proj())
         continue;
       // This presupposed that instructions are inserted into the
       // available list in a legality order; i.e. instructions that
       // must be inserted first are at the head of the list
       if (NodeFitsInBundle(n)) {
 #ifndef PRODUCT
         if (_cfg->C->trace_opto_output()) {
           tty->print("#   ChooseNodeToBundle: ");
           n->dump();
         }
 #endif
         return (n);
       }
     }
   }
   // Nothing fits in this bundle, choose the highest priority
 #ifndef PRODUCT
   if (_cfg->C->trace_opto_output()) {
     tty->print("#   ChooseNodeToBundle: ");
     _available[0]->dump();
   }
 #endif
   return _available[0];
 }
 void Scheduling::AddNodeToAvailableList(Node *n) {
   assert( !n->is_Proj(), "projections never directly made available" );
 #ifndef PRODUCT
   if (_cfg->C->trace_opto_output()) {
     tty->print("#   AddNodeToAvailableList: ");
     n->dump();
   }
 #endif
   int latency = _current_latency[n->_idx];
   // Insert in latency order (insertion sort)
   uint i;
   for ( i=0; i < _available.size(); i++ )
     if (_current_latency[_available[i]->_idx] > latency)
       break;
   // Special Check for compares following branches
   if( n->is_Mach() && _scheduled.size() > 0 ) {
     int op = n->as_Mach()->ideal_Opcode();
     Node *last = _scheduled[0];
     if( last->is_MachIf() && last->in(1) == n &&
         ( op == Op_CmpI ||
           op == Op_CmpU ||
           op == Op_CmpP ||
           op == Op_CmpF ||
           op == Op_CmpD ||
           op == Op_CmpL ) ) {
       // Recalculate position, moving to front of same latency
       for ( i=0 ; i < _available.size(); i++ )
         if (_current_latency[_available[i]->_idx] >= latency)
           break;
     }
   }
   // Insert the node in the available list
   _available.insert(i, n);
 #ifndef PRODUCT
   if (_cfg->C->trace_opto_output())
     dump_available();
 #endif
 }
 void Scheduling::DecrementUseCounts(Node *n, const Block *bb) {
   for ( uint i=0; i < n->len(); i++ ) {
     Node *def = n->in(i);
     if (!def) continue;
     if( def->is_Proj() )        // If this is a machine projection, then
       def = def->in(0);         // propagate usage thru to the base instruction
     if(_cfg->get_block_for_node(def) != bb) { // Ignore if not block-local
       continue;
     }
     // Compute the latency
     uint l = _bundle_cycle_number + n->latency(i);
     if (_current_latency[def->_idx] < l)
       _current_latency[def->_idx] = l;
     // If this does not have uses then schedule it
     if ((--_uses[def->_idx]) == 0)
       AddNodeToAvailableList(def);
   }
 }
 void Scheduling::AddNodeToBundle(Node *n, const Block *bb) {
 #ifndef PRODUCT
   if (_cfg->C->trace_opto_output()) {
     tty->print("#   AddNodeToBundle: ");
     n->dump();
   }
 #endif
   // Remove this from the available list
   uint i;
   for (i = 0; i < _available.size(); i++)
     if (_available[i] == n)
       break;
   assert(i < _available.size(), "entry in _available list not found");
   _available.remove(i);
   // See if this fits in the current bundle
   const Pipeline *node_pipeline = n->pipeline();
   const Pipeline_Use& node_usage = node_pipeline->resourceUse();
   // Check for instructions to be placed in the delay slot. We
   // do this before we actually schedule the current instruction,
   // because the delay slot follows the current instruction.
   if (Pipeline::_branch_has_delay_slot &&
       node_pipeline->hasBranchDelay() &&
       !_unconditional_delay_slot) {
     uint siz = _available.size();
     // Conditional branches can support an instruction that
     // is unconditionally executed and not dependent by the
     // branch, OR a conditionally executed instruction if
     // the branch is taken.  In practice, this means that
     // the first instruction at the branch target is
     // copied to the delay slot, and the branch goes to
     // the instruction after that at the branch target
     if ( n->is_MachBranch() ) {
       assert( !n->is_MachNullCheck(), "should not look for delay slot for Null Check" );
       assert( !n->is_Catch(),         "should not look for delay slot for Catch" );
 #ifndef PRODUCT
       _branches++;
 #endif
       // At least 1 instruction is on the available list
       // that is not dependent on the branch
       for (uint i = 0; i < siz; i++) {
         Node *d = _available[i];
         const Pipeline *avail_pipeline = d->pipeline();
         // Don't allow safepoints in the branch shadow, that will
         // cause a number of difficulties
         if ( avail_pipeline->instructionCount() == 1 &&
             !avail_pipeline->hasMultipleBundles() &&
             !avail_pipeline->hasBranchDelay() &&
             Pipeline::instr_has_unit_size() &&
             d->size(_regalloc) == Pipeline::instr_unit_size() &&
             NodeFitsInBundle(d) &&
             !node_bundling(d)->used_in_delay()) {
           if (d->is_Mach() && !d->is_MachSafePoint()) {
             // A node that fits in the delay slot was found, so we need to
             // set the appropriate bits in the bundle pipeline information so
             // that it correctly indicates resource usage.  Later, when we
             // attempt to add this instruction to the bundle, we will skip
             // setting the resource usage.
             _unconditional_delay_slot = d;
             node_bundling(n)->set_use_unconditional_delay();
             node_bundling(d)->set_used_in_unconditional_delay();
             _bundle_use.add_usage(avail_pipeline->resourceUse());
             _current_latency[d->_idx] = _bundle_cycle_number;
             _next_node = d;
             ++_bundle_instr_count;
 #ifndef PRODUCT
             _unconditional_delays++;
 #endif
             break;
           }
         }
       }
     }
     // No delay slot, add a nop to the usage
     if (!_unconditional_delay_slot) {
       // See if adding an instruction in the delay slot will overflow
       // the bundle.
       if (!NodeFitsInBundle(_nop)) {
 #ifndef PRODUCT
         if (_cfg->C->trace_opto_output())
           tty->print("#  *** STEP(1 instruction for delay slot) ***\n");
 #endif
         step(1);
       }
       _bundle_use.add_usage(_nop->pipeline()->resourceUse());
       _next_node = _nop;
       ++_bundle_instr_count;
     }
     // See if the instruction in the delay slot requires a
     // step of the bundles
     if (!NodeFitsInBundle(n)) {
 #ifndef PRODUCT
         if (_cfg->C->trace_opto_output())
           tty->print("#  *** STEP(branch won't fit) ***\n");
 #endif
         // Update the state information
         _bundle_instr_count = 0;
         _bundle_cycle_number += 1;
         _bundle_use.step(1);
     }
   }
   // Get the number of instructions
   uint instruction_count = node_pipeline->instructionCount();
   if (node_pipeline->mayHaveNoCode() && n->size(_regalloc) == 0)
     instruction_count = 0;
   // Compute the latency information
   uint delay = 0;
   if (instruction_count > 0 || !node_pipeline->mayHaveNoCode()) {
     int relative_latency = _current_latency[n->_idx] - _bundle_cycle_number;
     if (relative_latency < 0)
       relative_latency = 0;
     delay = _bundle_use.full_latency(relative_latency, node_usage);
     // Does not fit in this bundle, start a new one
     if (delay > 0) {
       step(delay);
 #ifndef PRODUCT
       if (_cfg->C->trace_opto_output())
         tty->print("#  *** STEP(%d) ***\n", delay);
 #endif
     }
   }
   // If this was placed in the delay slot, ignore it
   if (n != _unconditional_delay_slot) {
     if (delay == 0) {
       if (node_pipeline->hasMultipleBundles()) {
 #ifndef PRODUCT
         if (_cfg->C->trace_opto_output())
           tty->print("#  *** STEP(multiple instructions) ***\n");
 #endif
         step(1);
       }
       else if (instruction_count + _bundle_instr_count > Pipeline::_max_instrs_per_cycle) {
 #ifndef PRODUCT
         if (_cfg->C->trace_opto_output())
           tty->print("#  *** STEP(%d >= %d instructions) ***\n",
             instruction_count + _bundle_instr_count,
             Pipeline::_max_instrs_per_cycle);
 #endif
         step(1);
       }
     }
     if (node_pipeline->hasBranchDelay() && !_unconditional_delay_slot)
       _bundle_instr_count++;
     // Set the node's latency
     _current_latency[n->_idx] = _bundle_cycle_number;
     // Now merge the functional unit information
     if (instruction_count > 0 || !node_pipeline->mayHaveNoCode())
       _bundle_use.add_usage(node_usage);
     // Increment the number of instructions in this bundle
     _bundle_instr_count += instruction_count;
     // Remember this node for later
     if (n->is_Mach())
       _next_node = n;
   }
   // It's possible to have a BoxLock in the graph and in the _bbs mapping but
   // not in the bb->_nodes array.  This happens for debug-info-only BoxLocks.
   // 'Schedule' them (basically ignore in the schedule) but do not insert them
   // into the block.  All other scheduled nodes get put in the schedule here.
   int op = n->Opcode();
   if( (op == Op_Node && n->req() == 0) || // anti-dependence node OR
       (op != Op_Node &&         // Not an unused antidepedence node and
        // not an unallocated boxlock
        (OptoReg::is_valid(_regalloc->get_reg_first(n)) || op != Op_BoxLock)) ) {
     // Push any trailing projections
     if( bb->get_node(bb->number_of_nodes()-1) != n ) {
       for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
         Node *foi = n->fast_out(i);
         if( foi->is_Proj() )
           _scheduled.push(foi);
       }
     }
     // Put the instruction in the schedule list
     _scheduled.push(n);
   }
 #ifndef PRODUCT
   if (_cfg->C->trace_opto_output())
     dump_available();
 #endif
   // Walk all the definitions, decrementing use counts, and
   // if a definition has a 0 use count, place it in the available list.
   DecrementUseCounts(n,bb);
 }
 // This method sets the use count within a basic block.  We will ignore all
 // uses outside the current basic block.  As we are doing a backwards walk,
 // any node we reach that has a use count of 0 may be scheduled.  This also
 // avoids the problem of cyclic references from phi nodes, as long as phi
 // nodes are at the front of the basic block.  This method also initializes
 // the available list to the set of instructions that have no uses within this
 // basic block.
 void Scheduling::ComputeUseCount(const Block *bb) {
 #ifndef PRODUCT
   if (_cfg->C->trace_opto_output())
     tty->print("# -> ComputeUseCount\n");
 #endif
   // Clear the list of available and scheduled instructions, just in case
   _available.clear();
   _scheduled.clear();
   // No delay slot specified
   _unconditional_delay_slot = NULL;
 #ifdef ASSERT
   for( uint i=0; i < bb->number_of_nodes(); i++ )
     assert( _uses[bb->get_node(i)->_idx] == 0, "_use array not clean" );
 #endif
   // Force the _uses count to never go to zero for unscheduable pieces
   // of the block
   for( uint k = 0; k < _bb_start; k++ )
     _uses[bb->get_node(k)->_idx] = 1;
   for( uint l = _bb_end; l < bb->number_of_nodes(); l++ )
     _uses[bb->get_node(l)->_idx] = 1;
   // Iterate backwards over the instructions in the block.  Don't count the
   // branch projections at end or the block header instructions.
   for( uint j = _bb_end-1; j >= _bb_start; j-- ) {
     Node *n = bb->get_node(j);
     if( n->is_Proj() ) continue; // Projections handled another way
     // Account for all uses
     for ( uint k = 0; k < n->len(); k++ ) {
       Node *inp = n->in(k);
       if (!inp) continue;
       assert(inp != n, "no cycles allowed" );
       if (_cfg->get_block_for_node(inp) == bb) { // Block-local use?
         if (inp->is_Proj()) { // Skip through Proj's
           inp = inp->in(0);
         }
         ++_uses[inp->_idx];     // Count 1 block-local use
       }
     }
     // If this instruction has a 0 use count, then it is available
     if (!_uses[n->_idx]) {
       _current_latency[n->_idx] = _bundle_cycle_number;
       AddNodeToAvailableList(n);
     }
 #ifndef PRODUCT
     if (_cfg->C->trace_opto_output()) {
       tty->print("#   uses: %3d: ", _uses[n->_idx]);
       n->dump();
     }
 #endif
   }
 #ifndef PRODUCT
   if (_cfg->C->trace_opto_output())
     tty->print("# <- ComputeUseCount\n");
 #endif
 }
 // This routine performs scheduling on each basic block in reverse order,
 // using instruction latencies and taking into account function unit
 // availability.
 void Scheduling::DoScheduling() {
 #ifndef PRODUCT
   if (_cfg->C->trace_opto_output())
     tty->print("# -> DoScheduling\n");
 #endif
   Block *succ_bb = NULL;
   Block *bb;
   // Walk over all the basic blocks in reverse order
   for (int i = _cfg->number_of_blocks() - 1; i >= 0; succ_bb = bb, i--) {
     bb = _cfg->get_block(i);
 #ifndef PRODUCT
     if (_cfg->C->trace_opto_output()) {
       tty->print("#  Schedule BB#%03d (initial)\n", i);
       for (uint j = 0; j < bb->number_of_nodes(); j++) {
         bb->get_node(j)->dump();
       }
     }
 #endif
     // On the head node, skip processing
     if (bb == _cfg->get_root_block()) {
       continue;
     }
     // Skip empty, connector blocks
     if (bb->is_connector())
       continue;
     // If the following block is not the sole successor of
     // this one, then reset the pipeline information
     if (bb->_num_succs != 1 || bb->non_connector_successor(0) != succ_bb) {
 #ifndef PRODUCT
       if (_cfg->C->trace_opto_output()) {
         tty->print("*** bundle start of next BB, node %d, for %d instructions\n",
                    _next_node->_idx, _bundle_instr_count);
       }
 #endif
       step_and_clear();
     }
     // Leave untouched the starting instruction, any Phis, a CreateEx node
     // or Top.  bb->get_node(_bb_start) is the first schedulable instruction.
     _bb_end = bb->number_of_nodes()-1;
     for( _bb_start=1; _bb_start <= _bb_end; _bb_start++ ) {
       Node *n = bb->get_node(_bb_start);
       // Things not matched, like Phinodes and ProjNodes don't get scheduled.
       // Also, MachIdealNodes do not get scheduled
       if( !n->is_Mach() ) continue;     // Skip non-machine nodes
       MachNode *mach = n->as_Mach();
       int iop = mach->ideal_Opcode();
       if( iop == Op_CreateEx ) continue; // CreateEx is pinned
       if( iop == Op_Con ) continue;      // Do not schedule Top
       if( iop == Op_Node &&     // Do not schedule PhiNodes, ProjNodes
           mach->pipeline() == MachNode::pipeline_class() &&
           !n->is_SpillCopy() )  // Breakpoints, Prolog, etc
         continue;
       break;                    // Funny loop structure to be sure...
     }
     // Compute last "interesting" instruction in block - last instruction we
     // might schedule.  _bb_end points just after last schedulable inst.  We
     // normally schedule conditional branches (despite them being forced last
     // in the block), because they have delay slots we can fill.  Calls all
     // have their delay slots filled in the template expansions, so we don't
     // bother scheduling them.
     Node *last = bb->get_node(_bb_end);
     // Ignore trailing NOPs.
     while (_bb_end > 0 && last->is_Mach() &&
            last->as_Mach()->ideal_Opcode() == Op_Con) {
       last = bb->get_node(--_bb_end);
     }
     assert(!last->is_Mach() || last->as_Mach()->ideal_Opcode() != Op_Con, "");
     if( last->is_Catch() ||
        // Exclude unreachable path case when Halt node is in a separate block.
        (_bb_end > 1 && last->is_Mach() && last->as_Mach()->ideal_Opcode() == Op_Halt) ) {
       // There must be a prior call.  Skip it.
       while( !bb->get_node(--_bb_end)->is_MachCall() ) {
         assert( bb->get_node(_bb_end)->is_MachProj(), "skipping projections after expected call" );
       }
     } else if( last->is_MachNullCheck() ) {
       // Backup so the last null-checked memory instruction is
       // outside the schedulable range. Skip over the nullcheck,
       // projection, and the memory nodes.
       Node *mem = last->in(1);
       do {
         _bb_end--;
       } while (mem != bb->get_node(_bb_end));
     } else {
       // Set _bb_end to point after last schedulable inst.
       _bb_end++;
     }
     assert( _bb_start <= _bb_end, "inverted block ends" );
     // Compute the register antidependencies for the basic block
     ComputeRegisterAntidependencies(bb);
     if (_cfg->C->failing())  return;  // too many D-U pinch points
     // Compute intra-bb latencies for the nodes
     ComputeLocalLatenciesForward(bb);
     // Compute the usage within the block, and set the list of all nodes
     // in the block that have no uses within the block.
     ComputeUseCount(bb);
     // Schedule the remaining instructions in the block
     while ( _available.size() > 0 ) {
       Node *n = ChooseNodeToBundle();
       guarantee(n != NULL, "no nodes available");
       AddNodeToBundle(n,bb);
     }
     assert( _scheduled.size() == _bb_end - _bb_start, "wrong number of instructions" );
 #ifdef ASSERT
     for( uint l = _bb_start; l < _bb_end; l++ ) {
       Node *n = bb->get_node(l);
       uint m;
       for( m = 0; m < _bb_end-_bb_start; m++ )
         if( _scheduled[m] == n )
           break;
       assert( m < _bb_end-_bb_start, "instruction missing in schedule" );
     }
 #endif
     // Now copy the instructions (in reverse order) back to the block
     for ( uint k = _bb_start; k < _bb_end; k++ )
       bb->map_node(_scheduled[_bb_end-k-1], k);
 #ifndef PRODUCT
     if (_cfg->C->trace_opto_output()) {
       tty->print("#  Schedule BB#%03d (final)\n", i);
       uint current = 0;
       for (uint j = 0; j < bb->number_of_nodes(); j++) {
         Node *n = bb->get_node(j);
         if( valid_bundle_info(n) ) {
           Bundle *bundle = node_bundling(n);
           if (bundle->instr_count() > 0 || bundle->flags() > 0) {
             tty->print("*** Bundle: ");
             bundle->dump();
           }
           n->dump();
         }
       }
     }
 #endif
 #ifdef ASSERT
   verify_good_schedule(bb,"after block local scheduling");
 #endif
   }
 #ifndef PRODUCT
   if (_cfg->C->trace_opto_output())
     tty->print("# <- DoScheduling\n");
 #endif
   // Record final node-bundling array location
   _regalloc->C->set_node_bundling_base(_node_bundling_base);
 } // end DoScheduling
 // Verify that no live-range used in the block is killed in the block by a
 // wrong DEF.  This doesn't verify live-ranges that span blocks.
 // Check for edge existence.  Used to avoid adding redundant precedence edges.
 static bool edge_from_to( Node *from, Node *to ) {
   for( uint i=0; i<from->len(); i++ )
     if( from->in(i) == to )
       return true;
   return false;
 }
 #ifdef ASSERT
 void Scheduling::verify_do_def( Node *n, OptoReg::Name def, const char *msg ) {
   // Check for bad kills
   if( OptoReg::is_valid(def) ) { // Ignore stores & control flow
     Node *prior_use = _reg_node[def];
     if( prior_use && !edge_from_to(prior_use,n) ) {
       tty->print("%s = ",OptoReg::as_VMReg(def)->name());
       n->dump();
       tty->print_cr("...");
       prior_use->dump();
       assert(edge_from_to(prior_use,n),msg);
     }
     _reg_node.map(def,NULL); // Kill live USEs
   }
 }
 void Scheduling::verify_good_schedule( Block *b, const char *msg ) {
   // Zap to something reasonable for the verify code
   _reg_node.clear();
   // Walk over the block backwards.  Check to make sure each DEF doesn't
   // kill a live value (other than the one it's supposed to).  Add each
   // USE to the live set.
   for( uint i = b->number_of_nodes()-1; i >= _bb_start; i-- ) {
     Node *n = b->get_node(i);
     int n_op = n->Opcode();
     if( n_op == Op_MachProj && n->ideal_reg() == MachProjNode::fat_proj ) {
       // Fat-proj kills a slew of registers
       RegMask rm = n->out_RegMask();// Make local copy
       while( rm.is_NotEmpty() ) {
         OptoReg::Name kill = rm.find_first_elem();
         rm.Remove(kill);
         verify_do_def( n, kill, msg );
       }
     } else if( n_op != Op_Node ) { // Avoid brand new antidependence nodes
       // Get DEF'd registers the normal way
       verify_do_def( n, _regalloc->get_reg_first(n), msg );
       verify_do_def( n, _regalloc->get_reg_second(n), msg );
     }
     // Now make all USEs live
     for( uint i=1; i<n->req(); i++ ) {
       Node *def = n->in(i);
       assert(def != 0, "input edge required");
       OptoReg::Name reg_lo = _regalloc->get_reg_first(def);
       OptoReg::Name reg_hi = _regalloc->get_reg_second(def);
       if( OptoReg::is_valid(reg_lo) ) {
         assert(!_reg_node[reg_lo] || edge_from_to(_reg_node[reg_lo],def), msg);
         _reg_node.map(reg_lo,n);
       }
       if( OptoReg::is_valid(reg_hi) ) {
         assert(!_reg_node[reg_hi] || edge_from_to(_reg_node[reg_hi],def), msg);
         _reg_node.map(reg_hi,n);
       }
     }
   }
   // Zap to something reasonable for the Antidependence code
   _reg_node.clear();
 }
 #endif
 // Conditionally add precedence edges.  Avoid putting edges on Projs.
 static void add_prec_edge_from_to( Node *from, Node *to ) {
   if( from->is_Proj() ) {       // Put precedence edge on Proj's input
     assert( from->req() == 1 && (from->len() == 1 || from->in(1)==0), "no precedence edges on projections" );
     from = from->in(0);
   }
   if( from != to &&             // No cycles (for things like LD L0,[L0+4] )
       !edge_from_to( from, to ) ) // Avoid duplicate edge
     from->add_prec(to);
 }
 void Scheduling::anti_do_def( Block *b, Node *def, OptoReg::Name def_reg, int is_def ) {
   if( !OptoReg::is_valid(def_reg) ) // Ignore stores & control flow
     return;
   Node *pinch = _reg_node[def_reg]; // Get pinch point
   if ((pinch == NULL) || _cfg->get_block_for_node(pinch) != b || // No pinch-point yet?
       is_def ) {    // Check for a true def (not a kill)
     _reg_node.map(def_reg,def); // Record def/kill as the optimistic pinch-point
     return;
   }
   Node *kill = def;             // Rename 'def' to more descriptive 'kill'
   debug_only( def = (Node*)0xdeadbeef; )
   // After some number of kills there _may_ be a later def
   Node *later_def = NULL;
   // Finding a kill requires a real pinch-point.
   // Check for not already having a pinch-point.
   // Pinch points are Op_Node's.
   if( pinch->Opcode() != Op_Node ) { // Or later-def/kill as pinch-point?
     later_def = pinch;            // Must be def/kill as optimistic pinch-point
     if ( _pinch_free_list.size() > 0) {
       pinch = _pinch_free_list.pop();
     } else {
       pinch = new (_cfg->C) Node(1); // Pinch point to-be
     }
     if (pinch->_idx >= _regalloc->node_regs_max_index()) {
       _cfg->C->record_method_not_compilable("too many D-U pinch points");
       return;
     }
     _cfg->map_node_to_block(pinch, b);      // Pretend it's valid in this block (lazy init)
     _reg_node.map(def_reg,pinch); // Record pinch-point
     //_regalloc->set_bad(pinch->_idx); // Already initialized this way.
     if( later_def->outcnt() == 0 || later_def->ideal_reg() == MachProjNode::fat_proj ) { // Distinguish def from kill
       pinch->init_req(0, _cfg->C->top());     // set not NULL for the next call
       add_prec_edge_from_to(later_def,pinch); // Add edge from kill to pinch
       later_def = NULL;           // and no later def
     }
     pinch->set_req(0,later_def);  // Hook later def so we can find it
   } else {                        // Else have valid pinch point
     if( pinch->in(0) )            // If there is a later-def
       later_def = pinch->in(0);   // Get it
   }
   // Add output-dependence edge from later def to kill
   if( later_def )               // If there is some original def
     add_prec_edge_from_to(later_def,kill); // Add edge from def to kill
   // See if current kill is also a use, and so is forced to be the pinch-point.
   if( pinch->Opcode() == Op_Node ) {
     Node *uses = kill->is_Proj() ? kill->in(0) : kill;
     for( uint i=1; i<uses->req(); i++ ) {
       if( _regalloc->get_reg_first(uses->in(i)) == def_reg ||
           _regalloc->get_reg_second(uses->in(i)) == def_reg ) {
         // Yes, found a use/kill pinch-point
         pinch->set_req(0,NULL);  //
         pinch->replace_by(kill); // Move anti-dep edges up
         pinch = kill;
         _reg_node.map(def_reg,pinch);
         return;
       }
     }
   }
   // Add edge from kill to pinch-point
   add_prec_edge_from_to(kill,pinch);
 }
 void Scheduling::anti_do_use( Block *b, Node *use, OptoReg::Name use_reg ) {
   if( !OptoReg::is_valid(use_reg) ) // Ignore stores & control flow
     return;
   Node *pinch = _reg_node[use_reg]; // Get pinch point
   // Check for no later def_reg/kill in block
   if ((pinch != NULL) && _cfg->get_block_for_node(pinch) == b &&
       // Use has to be block-local as well
       _cfg->get_block_for_node(use) == b) {
     if( pinch->Opcode() == Op_Node && // Real pinch-point (not optimistic?)
         pinch->req() == 1 ) {   // pinch not yet in block?
       pinch->del_req(0);        // yank pointer to later-def, also set flag
       // Insert the pinch-point in the block just after the last use
       b->insert_node(pinch, b->find_node(use) + 1);
       _bb_end++;                // Increase size scheduled region in block
     }
     add_prec_edge_from_to(pinch,use);
   }
 }
 // We insert antidependences between the reads and following write of
 // allocated registers to prevent illegal code motion. Hopefully, the
 // number of added references should be fairly small, especially as we
 // are only adding references within the current basic block.
 void Scheduling::ComputeRegisterAntidependencies(Block *b) {
 #ifdef ASSERT
   verify_good_schedule(b,"before block local scheduling");
 #endif
   // A valid schedule, for each register independently, is an endless cycle
   // of: a def, then some uses (connected to the def by true dependencies),
   // then some kills (defs with no uses), finally the cycle repeats with a new
   // def.  The uses are allowed to float relative to each other, as are the
   // kills.  No use is allowed to slide past a kill (or def).  This requires
   // antidependencies between all uses of a single def and all kills that
   // follow, up to the next def.  More edges are redundant, because later defs
   // & kills are already serialized with true or antidependencies.  To keep
   // the edge count down, we add a 'pinch point' node if there's more than
   // one use or more than one kill/def.
   // We add dependencies in one bottom-up pass.
   // For each instruction we handle it's DEFs/KILLs, then it's USEs.
   // For each DEF/KILL, we check to see if there's a prior DEF/KILL for this
   // register.  If not, we record the DEF/KILL in _reg_node, the
   // register-to-def mapping.  If there is a prior DEF/KILL, we insert a
   // "pinch point", a new Node that's in the graph but not in the block.
   // We put edges from the prior and current DEF/KILLs to the pinch point.
   // We put the pinch point in _reg_node.  If there's already a pinch point
   // we merely add an edge from the current DEF/KILL to the pinch point.
   // After doing the DEF/KILLs, we handle USEs.  For each used register, we
   // put an edge from the pinch point to the USE.
   // To be expedient, the _reg_node array is pre-allocated for the whole
   // compilation.  _reg_node is lazily initialized; it either contains a NULL,
   // or a valid def/kill/pinch-point, or a leftover node from some prior
   // block.  Leftover node from some prior block is treated like a NULL (no
   // prior def, so no anti-dependence needed).  Valid def is distinguished by
   // it being in the current block.
   bool fat_proj_seen = false;
   uint last_safept = _bb_end-1;
   Node* end_node         = (_bb_end-1 >= _bb_start) ? b->get_node(last_safept) : NULL;
   Node* last_safept_node = end_node;
   for( uint i = _bb_end-1; i >= _bb_start; i-- ) {
     Node *n = b->get_node(i);
     int is_def = n->outcnt();   // def if some uses prior to adding precedence edges
     if( n->is_MachProj() && n->ideal_reg() == MachProjNode::fat_proj ) {
       // Fat-proj kills a slew of registers
       // This can add edges to 'n' and obscure whether or not it was a def,
       // hence the is_def flag.
       fat_proj_seen = true;
       RegMask rm = n->out_RegMask();// Make local copy
       while( rm.is_NotEmpty() ) {
         OptoReg::Name kill = rm.find_first_elem();
         rm.Remove(kill);
         anti_do_def( b, n, kill, is_def );
       }
     } else {
       // Get DEF'd registers the normal way
       anti_do_def( b, n, _regalloc->get_reg_first(n), is_def );
       anti_do_def( b, n, _regalloc->get_reg_second(n), is_def );
     }
     // Kill projections on a branch should appear to occur on the
     // branch, not afterwards, so grab the masks from the projections
     // and process them.
     if (n->is_MachBranch() || n->is_Mach() && n->as_Mach()->ideal_Opcode() == Op_Jump) {
       for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
         Node* use = n->fast_out(i);
         if (use->is_Proj()) {
           RegMask rm = use->out_RegMask();// Make local copy
           while( rm.is_NotEmpty() ) {
             OptoReg::Name kill = rm.find_first_elem();
             rm.Remove(kill);
             anti_do_def( b, n, kill, false );
           }
         }
       }
     }
     // Check each register used by this instruction for a following DEF/KILL
     // that must occur afterward and requires an anti-dependence edge.
     for( uint j=0; j<n->req(); j++ ) {
       Node *def = n->in(j);
       if( def ) {
         assert( !def->is_MachProj() || def->ideal_reg() != MachProjNode::fat_proj, "" );
         anti_do_use( b, n, _regalloc->get_reg_first(def) );
         anti_do_use( b, n, _regalloc->get_reg_second(def) );
       }
     }
     // Do not allow defs of new derived values to float above GC
     // points unless the base is definitely available at the GC point.
     Node *m = b->get_node(i);
     // Add precedence edge from following safepoint to use of derived pointer
     if( last_safept_node != end_node &&
         m != last_safept_node) {
       for (uint k = 1; k < m->req(); k++) {
         const Type *t = m->in(k)->bottom_type();
         if( t->isa_oop_ptr() &&
             t->is_ptr()->offset() != 0 ) {
           last_safept_node->add_prec( m );
           break;
         }
       }
     }
     if( n->jvms() ) {           // Precedence edge from derived to safept
       // Check if last_safept_node was moved by pinch-point insertion in anti_do_use()
       if( b->get_node(last_safept) != last_safept_node ) {
         last_safept = b->find_node(last_safept_node);
       }
       for( uint j=last_safept; j > i; j-- ) {
         Node *mach = b->get_node(j);
         if( mach->is_Mach() && mach->as_Mach()->ideal_Opcode() == Op_AddP )
           mach->add_prec( n );
       }
       last_safept = i;
       last_safept_node = m;
     }
   }
   if (fat_proj_seen) {
     // Garbage collect pinch nodes that were not consumed.
     // They are usually created by a fat kill MachProj for a call.
     garbage_collect_pinch_nodes();
   }
 }
 // Garbage collect pinch nodes for reuse by other blocks.
 //
 // The block scheduler's insertion of anti-dependence
 // edges creates many pinch nodes when the block contains
 // 2 or more Calls.  A pinch node is used to prevent a
 // combinatorial explosion of edges.  If a set of kills for a
 // register is anti-dependent on a set of uses (or defs), rather
 // than adding an edge in the graph between each pair of kill
 // and use (or def), a pinch is inserted between them:
 //
 //            use1   use2  use3
 //                \   |   /
 //                 \  |  /
 //                  pinch
 //                 /  |  \
 //                /   |   \
 //            kill1 kill2 kill3
 //
 // One pinch node is created per register killed when
 // the second call is encountered during a backwards pass
 // over the block.  Most of these pinch nodes are never
 // wired into the graph because the register is never
 // used or def'ed in the block.
 //
 void Scheduling::garbage_collect_pinch_nodes() {
 #ifndef PRODUCT
     if (_cfg->C->trace_opto_output()) tty->print("Reclaimed pinch nodes:");
 #endif
     int trace_cnt = 0;
     for (uint k = 0; k < _reg_node.Size(); k++) {
       Node* pinch = _reg_node[k];
       if ((pinch != NULL) && pinch->Opcode() == Op_Node &&
           // no predecence input edges
           (pinch->req() == pinch->len() || pinch->in(pinch->req()) == NULL) ) {
         cleanup_pinch(pinch);
         _pinch_free_list.push(pinch);
         _reg_node.map(k, NULL);
 #ifndef PRODUCT
         if (_cfg->C->trace_opto_output()) {
           trace_cnt++;
           if (trace_cnt > 40) {
             tty->print("\n");
             trace_cnt = 0;
           }
           tty->print(" %d", pinch->_idx);
         }
 #endif
       }
     }
 #ifndef PRODUCT
     if (_cfg->C->trace_opto_output()) tty->print("\n");
 #endif
 }
 // Clean up a pinch node for reuse.
 void Scheduling::cleanup_pinch( Node *pinch ) {
   assert (pinch && pinch->Opcode() == Op_Node && pinch->req() == 1, "just checking");
   for (DUIterator_Last imin, i = pinch->last_outs(imin); i >= imin; ) {
     Node* use = pinch->last_out(i);
     uint uses_found = 0;
     for (uint j = use->req(); j < use->len(); j++) {
       if (use->in(j) == pinch) {
         use->rm_prec(j);
         uses_found++;
       }
     }
     assert(uses_found > 0, "must be a precedence edge");
     i -= uses_found;    // we deleted 1 or more copies of this edge
   }
   // May have a later_def entry
   pinch->set_req(0, NULL);
 }
 #ifndef PRODUCT
 void Scheduling::dump_available() const {
   tty->print("#Availist  ");
   for (uint i = 0; i < _available.size(); i++)
     tty->print(" N%d/l%d", _available[i]->_idx,_current_latency[_available[i]->_idx]);
   tty->cr();
 }
 // Print Scheduling Statistics
 void Scheduling::print_statistics() {
   // Print the size added by nops for bundling
   tty->print("Nops added %d bytes to total of %d bytes",
     _total_nop_size, _total_method_size);
   if (_total_method_size > 0)
     tty->print(", for %.2f%%",
       ((double)_total_nop_size) / ((double) _total_method_size) * 100.0);
   tty->print("\n");
   // Print the number of branch shadows filled
   if (Pipeline::_branch_has_delay_slot) {
     tty->print("Of %d branches, %d had unconditional delay slots filled",
       _total_branches, _total_unconditional_delays);
     if (_total_branches > 0)
       tty->print(", for %.2f%%",
         ((double)_total_unconditional_delays) / ((double)_total_branches) * 100.0);
     tty->print("\n");
   }
   uint total_instructions = 0, total_bundles = 0;
   for (uint i = 1; i <= Pipeline::_max_instrs_per_cycle; i++) {
     uint bundle_count   = _total_instructions_per_bundle[i];
     total_instructions += bundle_count * i;
     total_bundles      += bundle_count;
   }
   if (total_bundles > 0)
     tty->print("Average ILP (excluding nops) is %.2f\n",
       ((double)total_instructions) / ((double)total_bundles));
 }
 #endif

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/opto/output.cpp@a433eb716ce1 (annotated)

src/share/vm/opto/output.cpp