| /* |
| * 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 "memory/allocation.inline.hpp" |
| #include "opto/chaitin.hpp" |
| #include "opto/machnode.hpp" |
| |
| // See if this register (or pairs, or vector) already contains the value. |
| static bool register_contains_value(Node* val, OptoReg::Name reg, int n_regs, |
| Node_List& value) { |
| for (int i = 0; i < n_regs; i++) { |
| OptoReg::Name nreg = OptoReg::add(reg,-i); |
| if (value[nreg] != val) |
| return false; |
| } |
| return true; |
| } |
| |
| //---------------------------may_be_copy_of_callee----------------------------- |
| // Check to see if we can possibly be a copy of a callee-save value. |
| bool PhaseChaitin::may_be_copy_of_callee( Node *def ) const { |
| // Short circuit if there are no callee save registers |
| if (_matcher.number_of_saved_registers() == 0) return false; |
| |
| // Expect only a spill-down and reload on exit for callee-save spills. |
| // Chains of copies cannot be deep. |
| // 5008997 - This is wishful thinking. Register allocator seems to |
| // be splitting live ranges for callee save registers to such |
| // an extent that in large methods the chains can be very long |
| // (50+). The conservative answer is to return true if we don't |
| // know as this prevents optimizations from occurring. |
| |
| const int limit = 60; |
| int i; |
| for( i=0; i < limit; i++ ) { |
| if( def->is_Proj() && def->in(0)->is_Start() && |
| _matcher.is_save_on_entry(lrgs(_lrg_map.live_range_id(def)).reg())) |
| return true; // Direct use of callee-save proj |
| if( def->is_Copy() ) // Copies carry value through |
| def = def->in(def->is_Copy()); |
| else if( def->is_Phi() ) // Phis can merge it from any direction |
| def = def->in(1); |
| else |
| break; |
| guarantee(def != NULL, "must not resurrect dead copy"); |
| } |
| // If we reached the end and didn't find a callee save proj |
| // then this may be a callee save proj so we return true |
| // as the conservative answer. If we didn't reach then end |
| // we must have discovered that it was not a callee save |
| // else we would have returned. |
| return i == limit; |
| } |
| |
| //------------------------------yank----------------------------------- |
| // Helper function for yank_if_dead |
| int PhaseChaitin::yank( Node *old, Block *current_block, Node_List *value, Node_List *regnd ) { |
| int blk_adjust=0; |
| Block *oldb = _cfg.get_block_for_node(old); |
| oldb->find_remove(old); |
| // Count 1 if deleting an instruction from the current block |
| if (oldb == current_block) { |
| blk_adjust++; |
| } |
| _cfg.unmap_node_from_block(old); |
| OptoReg::Name old_reg = lrgs(_lrg_map.live_range_id(old)).reg(); |
| if( regnd && (*regnd)[old_reg]==old ) { // Instruction is currently available? |
| value->map(old_reg,NULL); // Yank from value/regnd maps |
| regnd->map(old_reg,NULL); // This register's value is now unknown |
| } |
| return blk_adjust; |
| } |
| |
| #ifdef ASSERT |
| static bool expected_yanked_node(Node *old, Node *orig_old) { |
| // This code is expected only next original nodes: |
| // - load from constant table node which may have next data input nodes: |
| // MachConstantBase, MachTemp, MachSpillCopy |
| // - Phi nodes that are considered Junk |
| // - load constant node which may have next data input nodes: |
| // MachTemp, MachSpillCopy |
| // - MachSpillCopy |
| // - MachProj and Copy dead nodes |
| if (old->is_MachSpillCopy()) { |
| return true; |
| } else if (old->is_Con()) { |
| return true; |
| } else if (old->is_MachProj()) { // Dead kills projection of Con node |
| return (old == orig_old); |
| } else if (old->is_Copy()) { // Dead copy of a callee-save value |
| return (old == orig_old); |
| } else if (old->is_MachTemp()) { |
| return orig_old->is_Con(); |
| } else if (old->is_Phi()) { // Junk phi's |
| return true; |
| } else if (old->is_MachConstantBase()) { |
| return (orig_old->is_Con() && orig_old->is_MachConstant()); |
| } |
| return false; |
| } |
| #endif |
| |
| //------------------------------yank_if_dead----------------------------------- |
| // Removed edges from 'old'. Yank if dead. Return adjustment counts to |
| // iterators in the current block. |
| int PhaseChaitin::yank_if_dead_recurse(Node *old, Node *orig_old, Block *current_block, |
| Node_List *value, Node_List *regnd) { |
| int blk_adjust=0; |
| if (old->outcnt() == 0 && old != C->top()) { |
| #ifdef ASSERT |
| if (!expected_yanked_node(old, orig_old)) { |
| tty->print_cr("=============================================="); |
| tty->print_cr("orig_old:"); |
| orig_old->dump(); |
| tty->print_cr("old:"); |
| old->dump(); |
| assert(false, "unexpected yanked node"); |
| } |
| if (old->is_Con()) |
| orig_old = old; // Reset to satisfy expected nodes checks. |
| #endif |
| blk_adjust += yank(old, current_block, value, regnd); |
| |
| for (uint i = 1; i < old->req(); i++) { |
| Node* n = old->in(i); |
| if (n != NULL) { |
| old->set_req(i, NULL); |
| blk_adjust += yank_if_dead_recurse(n, orig_old, current_block, value, regnd); |
| } |
| } |
| // Disconnect control and remove precedence edges if any exist |
| old->disconnect_inputs(NULL, C); |
| } |
| return blk_adjust; |
| } |
| |
| //------------------------------use_prior_register----------------------------- |
| // Use the prior value instead of the current value, in an effort to make |
| // the current value go dead. Return block iterator adjustment, in case |
| // we yank some instructions from this block. |
| int PhaseChaitin::use_prior_register( Node *n, uint idx, Node *def, Block *current_block, Node_List &value, Node_List ®nd ) { |
| // No effect? |
| if( def == n->in(idx) ) return 0; |
| // Def is currently dead and can be removed? Do not resurrect |
| if( def->outcnt() == 0 ) return 0; |
| |
| // Not every pair of physical registers are assignment compatible, |
| // e.g. on sparc floating point registers are not assignable to integer |
| // registers. |
| const LRG &def_lrg = lrgs(_lrg_map.live_range_id(def)); |
| OptoReg::Name def_reg = def_lrg.reg(); |
| const RegMask &use_mask = n->in_RegMask(idx); |
| bool can_use = ( RegMask::can_represent(def_reg) ? (use_mask.Member(def_reg) != 0) |
| : (use_mask.is_AllStack() != 0)); |
| if (!RegMask::is_vector(def->ideal_reg())) { |
| // Check for a copy to or from a misaligned pair. |
| // It is workaround for a sparc with misaligned pairs. |
| can_use = can_use && !use_mask.is_misaligned_pair() && !def_lrg.mask().is_misaligned_pair(); |
| } |
| if (!can_use) |
| return 0; |
| |
| // Capture the old def in case it goes dead... |
| Node *old = n->in(idx); |
| |
| // Save-on-call copies can only be elided if the entire copy chain can go |
| // away, lest we get the same callee-save value alive in 2 locations at |
| // once. We check for the obvious trivial case here. Although it can |
| // sometimes be elided with cooperation outside our scope, here we will just |
| // miss the opportunity. :-( |
| if( may_be_copy_of_callee(def) ) { |
| if( old->outcnt() > 1 ) return 0; // We're the not last user |
| int idx = old->is_Copy(); |
| assert( idx, "chain of copies being removed" ); |
| Node *old2 = old->in(idx); // Chain of copies |
| if( old2->outcnt() > 1 ) return 0; // old is not the last user |
| int idx2 = old2->is_Copy(); |
| if( !idx2 ) return 0; // Not a chain of 2 copies |
| if( def != old2->in(idx2) ) return 0; // Chain of exactly 2 copies |
| } |
| |
| // Use the new def |
| n->set_req(idx,def); |
| _post_alloc++; |
| |
| // Is old def now dead? We successfully yanked a copy? |
| return yank_if_dead(old,current_block,&value,®nd); |
| } |
| |
| |
| //------------------------------skip_copies------------------------------------ |
| // Skip through any number of copies (that don't mod oop-i-ness) |
| Node *PhaseChaitin::skip_copies( Node *c ) { |
| int idx = c->is_Copy(); |
| uint is_oop = lrgs(_lrg_map.live_range_id(c))._is_oop; |
| while (idx != 0) { |
| guarantee(c->in(idx) != NULL, "must not resurrect dead copy"); |
| if (lrgs(_lrg_map.live_range_id(c->in(idx)))._is_oop != is_oop) { |
| break; // casting copy, not the same value |
| } |
| c = c->in(idx); |
| idx = c->is_Copy(); |
| } |
| return c; |
| } |
| |
| //------------------------------elide_copy------------------------------------- |
| // Remove (bypass) copies along Node n, edge k. |
| int PhaseChaitin::elide_copy( Node *n, int k, Block *current_block, Node_List &value, Node_List ®nd, bool can_change_regs ) { |
| int blk_adjust = 0; |
| |
| uint nk_idx = _lrg_map.live_range_id(n->in(k)); |
| OptoReg::Name nk_reg = lrgs(nk_idx).reg(); |
| |
| // Remove obvious same-register copies |
| Node *x = n->in(k); |
| int idx; |
| while( (idx=x->is_Copy()) != 0 ) { |
| Node *copy = x->in(idx); |
| guarantee(copy != NULL, "must not resurrect dead copy"); |
| if(lrgs(_lrg_map.live_range_id(copy)).reg() != nk_reg) { |
| break; |
| } |
| blk_adjust += use_prior_register(n,k,copy,current_block,value,regnd); |
| if (n->in(k) != copy) { |
| break; // Failed for some cutout? |
| } |
| x = copy; // Progress, try again |
| } |
| |
| // Phis and 2-address instructions cannot change registers so easily - their |
| // outputs must match their input. |
| if( !can_change_regs ) |
| return blk_adjust; // Only check stupid copies! |
| |
| // Loop backedges won't have a value-mapping yet |
| if( &value == NULL ) return blk_adjust; |
| |
| // Skip through all copies to the _value_ being used. Do not change from |
| // int to pointer. This attempts to jump through a chain of copies, where |
| // intermediate copies might be illegal, i.e., value is stored down to stack |
| // then reloaded BUT survives in a register the whole way. |
| Node *val = skip_copies(n->in(k)); |
| if (val == x) return blk_adjust; // No progress? |
| |
| int n_regs = RegMask::num_registers(val->ideal_reg()); |
| uint val_idx = _lrg_map.live_range_id(val); |
| OptoReg::Name val_reg = lrgs(val_idx).reg(); |
| |
| // See if it happens to already be in the correct register! |
| // (either Phi's direct register, or the common case of the name |
| // never-clobbered original-def register) |
| if (register_contains_value(val, val_reg, n_regs, value)) { |
| blk_adjust += use_prior_register(n,k,regnd[val_reg],current_block,value,regnd); |
| if( n->in(k) == regnd[val_reg] ) // Success! Quit trying |
| return blk_adjust; |
| } |
| |
| // See if we can skip the copy by changing registers. Don't change from |
| // using a register to using the stack unless we know we can remove a |
| // copy-load. Otherwise we might end up making a pile of Intel cisc-spill |
| // ops reading from memory instead of just loading once and using the |
| // register. |
| |
| // Also handle duplicate copies here. |
| const Type *t = val->is_Con() ? val->bottom_type() : NULL; |
| |
| // Scan all registers to see if this value is around already |
| for( uint reg = 0; reg < (uint)_max_reg; reg++ ) { |
| if (reg == (uint)nk_reg) { |
| // Found ourselves so check if there is only one user of this |
| // copy and keep on searching for a better copy if so. |
| bool ignore_self = true; |
| x = n->in(k); |
| DUIterator_Fast imax, i = x->fast_outs(imax); |
| Node* first = x->fast_out(i); i++; |
| while (i < imax && ignore_self) { |
| Node* use = x->fast_out(i); i++; |
| if (use != first) ignore_self = false; |
| } |
| if (ignore_self) continue; |
| } |
| |
| Node *vv = value[reg]; |
| if (n_regs > 1) { // Doubles and vectors check for aligned-adjacent set |
| uint last = (n_regs-1); // Looking for the last part of a set |
| if ((reg&last) != last) continue; // Wrong part of a set |
| if (!register_contains_value(vv, reg, n_regs, value)) continue; // Different value |
| } |
| if( vv == val || // Got a direct hit? |
| (t && vv && vv->bottom_type() == t && vv->is_Mach() && |
| vv->as_Mach()->rule() == val->as_Mach()->rule()) ) { // Or same constant? |
| assert( !n->is_Phi(), "cannot change registers at a Phi so easily" ); |
| if( OptoReg::is_stack(nk_reg) || // CISC-loading from stack OR |
| OptoReg::is_reg(reg) || // turning into a register use OR |
| regnd[reg]->outcnt()==1 ) { // last use of a spill-load turns into a CISC use |
| blk_adjust += use_prior_register(n,k,regnd[reg],current_block,value,regnd); |
| if( n->in(k) == regnd[reg] ) // Success! Quit trying |
| return blk_adjust; |
| } // End of if not degrading to a stack |
| } // End of if found value in another register |
| } // End of scan all machine registers |
| return blk_adjust; |
| } |
| |
| |
| // |
| // Check if nreg already contains the constant value val. Normal copy |
| // elimination doesn't doesn't work on constants because multiple |
| // nodes can represent the same constant so the type and rule of the |
| // MachNode must be checked to ensure equivalence. |
| // |
| bool PhaseChaitin::eliminate_copy_of_constant(Node* val, Node* n, |
| Block *current_block, |
| Node_List& value, Node_List& regnd, |
| OptoReg::Name nreg, OptoReg::Name nreg2) { |
| if (value[nreg] != val && val->is_Con() && |
| value[nreg] != NULL && value[nreg]->is_Con() && |
| (nreg2 == OptoReg::Bad || value[nreg] == value[nreg2]) && |
| value[nreg]->bottom_type() == val->bottom_type() && |
| value[nreg]->as_Mach()->rule() == val->as_Mach()->rule()) { |
| // This code assumes that two MachNodes representing constants |
| // which have the same rule and the same bottom type will produce |
| // identical effects into a register. This seems like it must be |
| // objectively true unless there are hidden inputs to the nodes |
| // but if that were to change this code would need to updated. |
| // Since they are equivalent the second one if redundant and can |
| // be removed. |
| // |
| // n will be replaced with the old value but n might have |
| // kills projections associated with it so remove them now so that |
| // yank_if_dead will be able to eliminate the copy once the uses |
| // have been transferred to the old[value]. |
| for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { |
| Node* use = n->fast_out(i); |
| if (use->is_Proj() && use->outcnt() == 0) { |
| // Kill projections have no users and one input |
| use->set_req(0, C->top()); |
| yank_if_dead(use, current_block, &value, ®nd); |
| --i; --imax; |
| } |
| } |
| _post_alloc++; |
| return true; |
| } |
| return false; |
| } |
| |
| // The algorithms works as follows: |
| // We traverse the block top to bottom. possibly_merge_multidef() is invoked for every input edge k |
| // of the instruction n. We check to see if the input is a multidef lrg. If it is, we record the fact that we've |
| // seen a definition (coming as an input) and add that fact to the reg2defuse array. The array maps registers to their |
| // current reaching definitions (we track only multidefs though). With each definition we also associate the first |
| // instruction we saw use it. If we encounter the situation when we observe an def (an input) that is a part of the |
| // same lrg but is different from the previous seen def we merge the two with a MachMerge node and substitute |
| // all the uses that we've seen so far to use the merge. After that we keep replacing the new defs in the same lrg |
| // as they get encountered with the merge node and keep adding these defs to the merge inputs. |
| void PhaseChaitin::merge_multidefs() { |
| NOT_PRODUCT( Compile::TracePhase t3("mergeMultidefs", &_t_mergeMultidefs, TimeCompiler); ) |
| ResourceMark rm; |
| // Keep track of the defs seen in registers and collect their uses in the block. |
| RegToDefUseMap reg2defuse(_max_reg, _max_reg, RegDefUse()); |
| for (uint i = 0; i < _cfg.number_of_blocks(); i++) { |
| Block* block = _cfg.get_block(i); |
| for (uint j = 1; j < block->number_of_nodes(); j++) { |
| Node* n = block->get_node(j); |
| if (n->is_Phi()) continue; |
| for (uint k = 1; k < n->req(); k++) { |
| j += possibly_merge_multidef(n, k, block, reg2defuse); |
| } |
| // Null out the value produced by the instruction itself, since we're only interested in defs |
| // implicitly defined by the uses. We are actually interested in tracking only redefinitions |
| // of the multidef lrgs in the same register. For that matter it's enough to track changes in |
| // the base register only and ignore other effects of multi-register lrgs and fat projections. |
| // It is also ok to ignore defs coming from singledefs. After an implicit overwrite by one of |
| // those our register is guaranteed to be used by another lrg and we won't attempt to merge it. |
| uint lrg = _lrg_map.live_range_id(n); |
| if (lrg > 0 && lrgs(lrg).is_multidef()) { |
| OptoReg::Name reg = lrgs(lrg).reg(); |
| reg2defuse.at(reg).clear(); |
| } |
| } |
| // Clear reg->def->use tracking for the next block |
| for (int j = 0; j < reg2defuse.length(); j++) { |
| reg2defuse.at(j).clear(); |
| } |
| } |
| } |
| |
| int PhaseChaitin::possibly_merge_multidef(Node *n, uint k, Block *block, RegToDefUseMap& reg2defuse) { |
| int blk_adjust = 0; |
| |
| uint lrg = _lrg_map.live_range_id(n->in(k)); |
| if (lrg > 0 && lrgs(lrg).is_multidef()) { |
| OptoReg::Name reg = lrgs(lrg).reg(); |
| |
| Node* def = reg2defuse.at(reg).def(); |
| if (def != NULL && lrg == _lrg_map.live_range_id(def) && def != n->in(k)) { |
| // Same lrg but different node, we have to merge. |
| MachMergeNode* merge; |
| if (def->is_MachMerge()) { // is it already a merge? |
| merge = def->as_MachMerge(); |
| } else { |
| merge = new (C) MachMergeNode(def); |
| |
| // Insert the merge node into the block before the first use. |
| uint use_index = block->find_node(reg2defuse.at(reg).first_use()); |
| block->insert_node(merge, use_index++); |
| _cfg.map_node_to_block(merge, block); |
| |
| // Let the allocator know about the new node, use the same lrg |
| _lrg_map.extend(merge->_idx, lrg); |
| blk_adjust++; |
| |
| // Fixup all the uses (there is at least one) that happened between the first |
| // use and before the current one. |
| for (; use_index < block->number_of_nodes(); use_index++) { |
| Node* use = block->get_node(use_index); |
| if (use == n) { |
| break; |
| } |
| use->replace_edge(def, merge); |
| } |
| } |
| if (merge->find_edge(n->in(k)) == -1) { |
| merge->add_req(n->in(k)); |
| } |
| n->set_req(k, merge); |
| } |
| |
| // update the uses |
| reg2defuse.at(reg).update(n->in(k), n); |
| } |
| |
| return blk_adjust; |
| } |
| |
| |
| //------------------------------post_allocate_copy_removal--------------------- |
| // Post-Allocation peephole copy removal. We do this in 1 pass over the |
| // basic blocks. We maintain a mapping of registers to Nodes (an array of |
| // Nodes indexed by machine register or stack slot number). NULL means that a |
| // register is not mapped to any Node. We can (want to have!) have several |
| // registers map to the same Node. We walk forward over the instructions |
| // updating the mapping as we go. At merge points we force a NULL if we have |
| // to merge 2 different Nodes into the same register. Phi functions will give |
| // us a new Node if there is a proper value merging. Since the blocks are |
| // arranged in some RPO, we will visit all parent blocks before visiting any |
| // successor blocks (except at loops). |
| // |
| // If we find a Copy we look to see if the Copy's source register is a stack |
| // slot and that value has already been loaded into some machine register; if |
| // so we use machine register directly. This turns a Load into a reg-reg |
| // Move. We also look for reloads of identical constants. |
| // |
| // When we see a use from a reg-reg Copy, we will attempt to use the copy's |
| // source directly and make the copy go dead. |
| void PhaseChaitin::post_allocate_copy_removal() { |
| NOT_PRODUCT( Compile::TracePhase t3("postAllocCopyRemoval", &_t_postAllocCopyRemoval, TimeCompiler); ) |
| ResourceMark rm; |
| |
| // Need a mapping from basic block Node_Lists. We need a Node_List to |
| // map from register number to value-producing Node. |
| Node_List **blk2value = NEW_RESOURCE_ARRAY( Node_List *, _cfg.number_of_blocks() + 1); |
| memset(blk2value, 0, sizeof(Node_List*) * (_cfg.number_of_blocks() + 1)); |
| // Need a mapping from basic block Node_Lists. We need a Node_List to |
| // map from register number to register-defining Node. |
| Node_List **blk2regnd = NEW_RESOURCE_ARRAY( Node_List *, _cfg.number_of_blocks() + 1); |
| memset(blk2regnd, 0, sizeof(Node_List*) * (_cfg.number_of_blocks() + 1)); |
| |
| // We keep unused Node_Lists on a free_list to avoid wasting |
| // memory. |
| GrowableArray<Node_List*> free_list = GrowableArray<Node_List*>(16); |
| |
| // For all blocks |
| for (uint i = 0; i < _cfg.number_of_blocks(); i++) { |
| uint j; |
| Block* block = _cfg.get_block(i); |
| |
| // Count of Phis in block |
| uint phi_dex; |
| for (phi_dex = 1; phi_dex < block->number_of_nodes(); phi_dex++) { |
| Node* phi = block->get_node(phi_dex); |
| if (!phi->is_Phi()) { |
| break; |
| } |
| } |
| |
| // If any predecessor has not been visited, we do not know the state |
| // of registers at the start. Check for this, while updating copies |
| // along Phi input edges |
| bool missing_some_inputs = false; |
| Block *freed = NULL; |
| for (j = 1; j < block->num_preds(); j++) { |
| Block* pb = _cfg.get_block_for_node(block->pred(j)); |
| // Remove copies along phi edges |
| for (uint k = 1; k < phi_dex; k++) { |
| elide_copy(block->get_node(k), j, block, *blk2value[pb->_pre_order], *blk2regnd[pb->_pre_order], false); |
| } |
| if (blk2value[pb->_pre_order]) { // Have a mapping on this edge? |
| // See if this predecessor's mappings have been used by everybody |
| // who wants them. If so, free 'em. |
| uint k; |
| for (k = 0; k < pb->_num_succs; k++) { |
| Block* pbsucc = pb->_succs[k]; |
| if (!blk2value[pbsucc->_pre_order] && pbsucc != block) { |
| break; // Found a future user |
| } |
| } |
| if (k >= pb->_num_succs) { // No more uses, free! |
| freed = pb; // Record last block freed |
| free_list.push(blk2value[pb->_pre_order]); |
| free_list.push(blk2regnd[pb->_pre_order]); |
| } |
| } else { // This block has unvisited (loopback) inputs |
| missing_some_inputs = true; |
| } |
| } |
| |
| |
| // Extract Node_List mappings. If 'freed' is non-zero, we just popped |
| // 'freed's blocks off the list |
| Node_List ®nd = *(free_list.is_empty() ? new Node_List() : free_list.pop()); |
| Node_List &value = *(free_list.is_empty() ? new Node_List() : free_list.pop()); |
| assert( !freed || blk2value[freed->_pre_order] == &value, "" ); |
| value.map(_max_reg,NULL); |
| regnd.map(_max_reg,NULL); |
| // Set mappings as OUR mappings |
| blk2value[block->_pre_order] = &value; |
| blk2regnd[block->_pre_order] = ®nd; |
| |
| // Initialize value & regnd for this block |
| if (missing_some_inputs) { |
| // Some predecessor has not yet been visited; zap map to empty |
| for (uint k = 0; k < (uint)_max_reg; k++) { |
| value.map(k,NULL); |
| regnd.map(k,NULL); |
| } |
| } else { |
| if( !freed ) { // Didn't get a freebie prior block |
| // Must clone some data |
| freed = _cfg.get_block_for_node(block->pred(1)); |
| Node_List &f_value = *blk2value[freed->_pre_order]; |
| Node_List &f_regnd = *blk2regnd[freed->_pre_order]; |
| for( uint k = 0; k < (uint)_max_reg; k++ ) { |
| value.map(k,f_value[k]); |
| regnd.map(k,f_regnd[k]); |
| } |
| } |
| // Merge all inputs together, setting to NULL any conflicts. |
| for (j = 1; j < block->num_preds(); j++) { |
| Block* pb = _cfg.get_block_for_node(block->pred(j)); |
| if (pb == freed) { |
| continue; // Did self already via freelist |
| } |
| Node_List &p_regnd = *blk2regnd[pb->_pre_order]; |
| for( uint k = 0; k < (uint)_max_reg; k++ ) { |
| if( regnd[k] != p_regnd[k] ) { // Conflict on reaching defs? |
| value.map(k,NULL); // Then no value handy |
| regnd.map(k,NULL); |
| } |
| } |
| } |
| } |
| |
| // For all Phi's |
| for (j = 1; j < phi_dex; j++) { |
| uint k; |
| Node *phi = block->get_node(j); |
| uint pidx = _lrg_map.live_range_id(phi); |
| OptoReg::Name preg = lrgs(_lrg_map.live_range_id(phi)).reg(); |
| |
| // Remove copies remaining on edges. Check for junk phi. |
| Node *u = NULL; |
| for (k = 1; k < phi->req(); k++) { |
| Node *x = phi->in(k); |
| if( phi != x && u != x ) // Found a different input |
| u = u ? NodeSentinel : x; // Capture unique input, or NodeSentinel for 2nd input |
| } |
| if (u != NodeSentinel) { // Junk Phi. Remove |
| phi->replace_by(u); |
| j -= yank_if_dead(phi, block, &value, ®nd); |
| phi_dex--; |
| continue; |
| } |
| // Note that if value[pidx] exists, then we merged no new values here |
| // and the phi is useless. This can happen even with the above phi |
| // removal for complex flows. I cannot keep the better known value here |
| // because locally the phi appears to define a new merged value. If I |
| // keep the better value then a copy of the phi, being unable to use the |
| // global flow analysis, can't "peek through" the phi to the original |
| // reaching value and so will act like it's defining a new value. This |
| // can lead to situations where some uses are from the old and some from |
| // the new values. Not illegal by itself but throws the over-strong |
| // assert in scheduling. |
| if( pidx ) { |
| value.map(preg,phi); |
| regnd.map(preg,phi); |
| int n_regs = RegMask::num_registers(phi->ideal_reg()); |
| for (int l = 1; l < n_regs; l++) { |
| OptoReg::Name preg_lo = OptoReg::add(preg,-l); |
| value.map(preg_lo,phi); |
| regnd.map(preg_lo,phi); |
| } |
| } |
| } |
| |
| // For all remaining instructions |
| for (j = phi_dex; j < block->number_of_nodes(); j++) { |
| Node* n = block->get_node(j); |
| |
| if(n->outcnt() == 0 && // Dead? |
| n != C->top() && // (ignore TOP, it has no du info) |
| !n->is_Proj() ) { // fat-proj kills |
| j -= yank_if_dead(n, block, &value, ®nd); |
| continue; |
| } |
| |
| // Improve reaching-def info. Occasionally post-alloc's liveness gives |
| // up (at loop backedges, because we aren't doing a full flow pass). |
| // The presence of a live use essentially asserts that the use's def is |
| // alive and well at the use (or else the allocator fubar'd). Take |
| // advantage of this info to set a reaching def for the use-reg. |
| uint k; |
| for (k = 1; k < n->req(); k++) { |
| Node *def = n->in(k); // n->in(k) is a USE; def is the DEF for this USE |
| guarantee(def != NULL, "no disconnected nodes at this point"); |
| uint useidx = _lrg_map.live_range_id(def); // useidx is the live range index for this USE |
| |
| if( useidx ) { |
| OptoReg::Name ureg = lrgs(useidx).reg(); |
| if( !value[ureg] ) { |
| int idx; // Skip occasional useless copy |
| while( (idx=def->is_Copy()) != 0 && |
| def->in(idx) != NULL && // NULL should not happen |
| ureg == lrgs(_lrg_map.live_range_id(def->in(idx))).reg()) |
| def = def->in(idx); |
| Node *valdef = skip_copies(def); // tighten up val through non-useless copies |
| value.map(ureg,valdef); // record improved reaching-def info |
| regnd.map(ureg, def); |
| // Record other half of doubles |
| uint def_ideal_reg = def->ideal_reg(); |
| int n_regs = RegMask::num_registers(def_ideal_reg); |
| for (int l = 1; l < n_regs; l++) { |
| OptoReg::Name ureg_lo = OptoReg::add(ureg,-l); |
| if (!value[ureg_lo] && |
| (!RegMask::can_represent(ureg_lo) || |
| lrgs(useidx).mask().Member(ureg_lo))) { // Nearly always adjacent |
| value.map(ureg_lo,valdef); // record improved reaching-def info |
| regnd.map(ureg_lo, def); |
| } |
| } |
| } |
| } |
| } |
| |
| const uint two_adr = n->is_Mach() ? n->as_Mach()->two_adr() : 0; |
| |
| // Remove copies along input edges |
| for (k = 1; k < n->req(); k++) { |
| j -= elide_copy(n, k, block, value, regnd, two_adr != k); |
| } |
| |
| // Unallocated Nodes define no registers |
| uint lidx = _lrg_map.live_range_id(n); |
| if (!lidx) { |
| continue; |
| } |
| |
| // Update the register defined by this instruction |
| OptoReg::Name nreg = lrgs(lidx).reg(); |
| // Skip through all copies to the _value_ being defined. |
| // Do not change from int to pointer |
| Node *val = skip_copies(n); |
| |
| // Clear out a dead definition before starting so that the |
| // elimination code doesn't have to guard against it. The |
| // definition could in fact be a kill projection with a count of |
| // 0 which is safe but since those are uninteresting for copy |
| // elimination just delete them as well. |
| if (regnd[nreg] != NULL && regnd[nreg]->outcnt() == 0) { |
| regnd.map(nreg, NULL); |
| value.map(nreg, NULL); |
| } |
| |
| uint n_ideal_reg = n->ideal_reg(); |
| int n_regs = RegMask::num_registers(n_ideal_reg); |
| if (n_regs == 1) { |
| // If Node 'n' does not change the value mapped by the register, |
| // then 'n' is a useless copy. Do not update the register->node |
| // mapping so 'n' will go dead. |
| if( value[nreg] != val ) { |
| if (eliminate_copy_of_constant(val, n, block, value, regnd, nreg, OptoReg::Bad)) { |
| j -= replace_and_yank_if_dead(n, nreg, block, value, regnd); |
| } else { |
| // Update the mapping: record new Node defined by the register |
| regnd.map(nreg,n); |
| // Update mapping for defined *value*, which is the defined |
| // Node after skipping all copies. |
| value.map(nreg,val); |
| } |
| } else if( !may_be_copy_of_callee(n) ) { |
| assert(n->is_Copy(), ""); |
| j -= replace_and_yank_if_dead(n, nreg, block, value, regnd); |
| } |
| } else if (RegMask::is_vector(n_ideal_reg)) { |
| // If Node 'n' does not change the value mapped by the register, |
| // then 'n' is a useless copy. Do not update the register->node |
| // mapping so 'n' will go dead. |
| if (!register_contains_value(val, nreg, n_regs, value)) { |
| // Update the mapping: record new Node defined by the register |
| regnd.map(nreg,n); |
| // Update mapping for defined *value*, which is the defined |
| // Node after skipping all copies. |
| value.map(nreg,val); |
| for (int l = 1; l < n_regs; l++) { |
| OptoReg::Name nreg_lo = OptoReg::add(nreg,-l); |
| regnd.map(nreg_lo, n ); |
| value.map(nreg_lo,val); |
| } |
| } else if (n->is_Copy()) { |
| // Note: vector can't be constant and can't be copy of calee. |
| j -= replace_and_yank_if_dead(n, nreg, block, value, regnd); |
| } |
| } else { |
| // If the value occupies a register pair, record same info |
| // in both registers. |
| OptoReg::Name nreg_lo = OptoReg::add(nreg,-1); |
| if( RegMask::can_represent(nreg_lo) && // Either a spill slot, or |
| !lrgs(lidx).mask().Member(nreg_lo) ) { // Nearly always adjacent |
| // Sparc occasionally has non-adjacent pairs. |
| // Find the actual other value |
| RegMask tmp = lrgs(lidx).mask(); |
| tmp.Remove(nreg); |
| nreg_lo = tmp.find_first_elem(); |
| } |
| if (value[nreg] != val || value[nreg_lo] != val) { |
| if (eliminate_copy_of_constant(val, n, block, value, regnd, nreg, nreg_lo)) { |
| j -= replace_and_yank_if_dead(n, nreg, block, value, regnd); |
| } else { |
| regnd.map(nreg , n ); |
| regnd.map(nreg_lo, n ); |
| value.map(nreg ,val); |
| value.map(nreg_lo,val); |
| } |
| } else if (!may_be_copy_of_callee(n)) { |
| assert(n->is_Copy(), ""); |
| j -= replace_and_yank_if_dead(n, nreg, block, value, regnd); |
| } |
| } |
| |
| // Fat projections kill many registers |
| if( n_ideal_reg == MachProjNode::fat_proj ) { |
| RegMask rm = n->out_RegMask(); |
| // wow, what an expensive iterator... |
| nreg = rm.find_first_elem(); |
| while( OptoReg::is_valid(nreg)) { |
| rm.Remove(nreg); |
| value.map(nreg,n); |
| regnd.map(nreg,n); |
| nreg = rm.find_first_elem(); |
| } |
| } |
| |
| } // End of for all instructions in the block |
| |
| } // End for all blocks |
| } |
