|
/*
* Copyright (c) 2000, 2022, 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 "compiler/compileLog.hpp"
#include "compiler/oopMap.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "opto/addnode.hpp"
#include "opto/block.hpp"
#include "opto/callnode.hpp"
#include "opto/cfgnode.hpp"
#include "opto/chaitin.hpp"
#include "opto/coalesce.hpp"
#include "opto/connode.hpp"
#include "opto/idealGraphPrinter.hpp"
#include "opto/indexSet.hpp"
#include "opto/machnode.hpp"
#include "opto/memnode.hpp"
#include "opto/movenode.hpp"
#include "opto/opcodes.hpp"
#include "opto/rootnode.hpp"
#include "utilities/align.hpp"
#ifndef PRODUCT
void LRG::dump() const {
ttyLocker ttyl;
tty->print("%d ",num_regs());
_mask.dump();
if( _msize_valid ) {
if( mask_size() == compute_mask_size() ) tty->print(", #%d ",_mask_size);
else tty->print(", #!!!_%d_vs_%d ",_mask_size,_mask.Size());
} else {
tty->print(", #?(%d) ",_mask.Size());
}
tty->print("EffDeg: ");
if( _degree_valid ) tty->print( "%d ", _eff_degree );
else tty->print("? ");
if( is_multidef() ) {
tty->print("MultiDef ");
if (_defs != NULL) {
tty->print("(");
for (int i = 0; i < _defs->length(); i++) {
tty->print("N%d ", _defs->at(i)->_idx);
}
tty->print(") ");
}
}
else if( _def == 0 ) tty->print("Dead ");
else tty->print("Def: N%d ",_def->_idx);
tty->print("Cost:%4.2g Area:%4.2g Score:%4.2g ",_cost,_area, score());
// Flags
if( _is_oop ) tty->print("Oop ");
if( _is_float ) tty->print("Float ");
if( _is_vector ) tty->print("Vector ");
if( _is_predicate ) tty->print("Predicate ");
if( _is_scalable ) tty->print("Scalable ");
if( _was_spilled1 ) tty->print("Spilled ");
if( _was_spilled2 ) tty->print("Spilled2 ");
if( _direct_conflict ) tty->print("Direct_conflict ");
if( _fat_proj ) tty->print("Fat ");
if( _was_lo ) tty->print("Lo ");
if( _has_copy ) tty->print("Copy ");
if( _at_risk ) tty->print("Risk ");
if( _must_spill ) tty->print("Must_spill ");
if( _is_bound ) tty->print("Bound ");
if( _msize_valid ) {
if( _degree_valid && lo_degree() ) tty->print("Trivial ");
}
tty->cr();
}
#endif
// Compute score from cost and area. Low score is best to spill.
static double raw_score( double cost, double area ) {
return cost - (area*RegisterCostAreaRatio) * 1.52588e-5;
}
double LRG::score() const {
// Scale _area by RegisterCostAreaRatio/64K then subtract from cost.
// Bigger area lowers score, encourages spilling this live range.
// Bigger cost raise score, prevents spilling this live range.
// (Note: 1/65536 is the magic constant below; I dont trust the C optimizer
// to turn a divide by a constant into a multiply by the reciprical).
double score = raw_score( _cost, _area);
// Account for area. Basically, LRGs covering large areas are better
// to spill because more other LRGs get freed up.
if( _area == 0.0 ) // No area? Then no progress to spill
return 1e35;
if( _was_spilled2 ) // If spilled once before, we are unlikely
return score + 1e30; // to make progress again.
if( _cost >= _area*3.0 ) // Tiny area relative to cost
return score + 1e17; // Probably no progress to spill
if( (_cost+_cost) >= _area*3.0 ) // Small area relative to cost
return score + 1e10; // Likely no progress to spill
return score;
}
#define NUMBUCKS 3
// Straight out of Tarjan's union-find algorithm
uint LiveRangeMap::find_compress(uint lrg) {
uint cur = lrg;
uint next = _uf_map.at(cur);
while (next != cur) { // Scan chain of equivalences
assert( next < cur, "always union smaller");
cur = next; // until find a fixed-point
next = _uf_map.at(cur);
}
// Core of union-find algorithm: update chain of
// equivalences to be equal to the root.
while (lrg != next) {
uint tmp = _uf_map.at(lrg);
_uf_map.at_put(lrg, next);
lrg = tmp;
}
return lrg;
}
// Reset the Union-Find map to identity
void LiveRangeMap::reset_uf_map(uint max_lrg_id) {
_max_lrg_id= max_lrg_id;
// Force the Union-Find mapping to be at least this large
_uf_map.at_put_grow(_max_lrg_id, 0);
// Initialize it to be the ID mapping.
for (uint i = 0; i < _max_lrg_id; ++i) {
_uf_map.at_put(i, i);
}
}
// Make all Nodes map directly to their final live range; no need for
// the Union-Find mapping after this call.
void LiveRangeMap::compress_uf_map_for_nodes() {
// For all Nodes, compress mapping
uint unique = _names.length();
for (uint i = 0; i < unique; ++i) {
uint lrg = _names.at(i);
uint compressed_lrg = find(lrg);
if (lrg != compressed_lrg) {
_names.at_put(i, compressed_lrg);
}
}
}
// Like Find above, but no path compress, so bad asymptotic behavior
uint LiveRangeMap::find_const(uint lrg) const {
if (!lrg) {
return lrg; // Ignore the zero LRG
}
// Off the end? This happens during debugging dumps when you got
// brand new live ranges but have not told the allocator yet.
if (lrg >= _max_lrg_id) {
return lrg;
}
uint next = _uf_map.at(lrg);
while (next != lrg) { // Scan chain of equivalences
assert(next < lrg, "always union smaller");
lrg = next; // until find a fixed-point
next = _uf_map.at(lrg);
}
return next;
}
PhaseChaitin::PhaseChaitin(uint unique, PhaseCFG &cfg, Matcher &matcher, bool scheduling_info_generated)
: PhaseRegAlloc(unique, cfg, matcher,
#ifndef PRODUCT
print_chaitin_statistics
#else
NULL
#endif
)
, _live(0)
, _lo_degree(0), _lo_stk_degree(0), _hi_degree(0), _simplified(0)
, _oldphi(unique)
#ifndef PRODUCT
, _trace_spilling(C->directive()->TraceSpillingOption)
#endif
, _lrg_map(Thread::current()->resource_area(), unique)
, _scheduling_info_generated(scheduling_info_generated)
, _sched_int_pressure(0, Matcher::int_pressure_limit())
, _sched_float_pressure(0, Matcher::float_pressure_limit())
, _scratch_int_pressure(0, Matcher::int_pressure_limit())
, _scratch_float_pressure(0, Matcher::float_pressure_limit())
{
Compile::TracePhase tp("ctorChaitin", &timers[_t_ctorChaitin]);
_high_frequency_lrg = MIN2(double(OPTO_LRG_HIGH_FREQ), _cfg.get_outer_loop_frequency());
// Build a list of basic blocks, sorted by frequency
_blks = NEW_RESOURCE_ARRAY(Block *, _cfg.number_of_blocks());
// Experiment with sorting strategies to speed compilation
double cutoff = BLOCK_FREQUENCY(1.0); // Cutoff for high frequency bucket
Block **buckets[NUMBUCKS]; // Array of buckets
uint buckcnt[NUMBUCKS]; // Array of bucket counters
double buckval[NUMBUCKS]; // Array of bucket value cutoffs
for (uint i = 0; i < NUMBUCKS; i++) {
buckets[i] = NEW_RESOURCE_ARRAY(Block *, _cfg.number_of_blocks());
buckcnt[i] = 0;
// Bump by three orders of magnitude each time
cutoff *= 0.001;
buckval[i] = cutoff;
for (uint j = 0; j < _cfg.number_of_blocks(); j++) {
buckets[i][j] = NULL;
}
}
// Sort blocks into buckets
for (uint i = 0; i < _cfg.number_of_blocks(); i++) {
for (uint j = 0; j < NUMBUCKS; j++) {
if ((j == NUMBUCKS - 1) || (_cfg.get_block(i)->_freq > buckval[j])) {
// Assign block to end of list for appropriate bucket
buckets[j][buckcnt[j]++] = _cfg.get_block(i);
break; // kick out of inner loop
}
}
}
// Dump buckets into final block array
uint blkcnt = 0;
for (uint i = 0; i < NUMBUCKS; i++) {
for (uint j = 0; j < buckcnt[i]; j++) {
_blks[blkcnt++] = buckets[i][j];
}
}
assert(blkcnt == _cfg.number_of_blocks(), "Block array not totally filled");
}
// union 2 sets together.
void PhaseChaitin::Union( const Node *src_n, const Node *dst_n ) {
uint src = _lrg_map.find(src_n);
uint dst = _lrg_map.find(dst_n);
assert(src, "");
assert(dst, "");
assert(src < _lrg_map.max_lrg_id(), "oob");
assert(dst < _lrg_map.max_lrg_id(), "oob");
assert(src < dst, "always union smaller");
_lrg_map.uf_map(dst, src);
}
void PhaseChaitin::new_lrg(const Node *x, uint lrg) {
// Make the Node->LRG mapping
_lrg_map.extend(x->_idx,lrg);
// Make the Union-Find mapping an identity function
_lrg_map.uf_extend(lrg, lrg);
}
int PhaseChaitin::clone_projs(Block* b, uint idx, Node* orig, Node* copy, uint& max_lrg_id) {
assert(b->find_node(copy) == (idx - 1), "incorrect insert index for copy kill projections");
DEBUG_ONLY( Block* borig = _cfg.get_block_for_node(orig); )
int found_projs = 0;
uint cnt = orig->outcnt();
for (uint i = 0; i < cnt; i++) {
Node* proj = orig->raw_out(i);
if (proj->is_MachProj()) {
assert(proj->outcnt() == 0, "only kill projections are expected here");
assert(_cfg.get_block_for_node(proj) == borig, "incorrect block for kill projections");
found_projs++;
// Copy kill projections after the cloned node
Node* kills = proj->clone();
kills->set_req(0, copy);
b->insert_node(kills, idx++);
_cfg.map_node_to_block(kills, b);
new_lrg(kills, max_lrg_id++);
}
}
return found_projs;
}
// Renumber the live ranges to compact them. Makes the IFG smaller.
void PhaseChaitin::compact() {
Compile::TracePhase tp("chaitinCompact", &timers[_t_chaitinCompact]);
// Current the _uf_map contains a series of short chains which are headed
// by a self-cycle. All the chains run from big numbers to little numbers.
// The Find() call chases the chains & shortens them for the next Find call.
// We are going to change this structure slightly. Numbers above a moving
// wave 'i' are unchanged. Numbers below 'j' point directly to their
// compacted live range with no further chaining. There are no chains or
// cycles below 'i', so the Find call no longer works.
uint j=1;
uint i;
for (i = 1; i < _lrg_map.max_lrg_id(); i++) {
uint lr = _lrg_map.uf_live_range_id(i);
// Ignore unallocated live ranges
if (!lr) {
continue;
}
assert(lr <= i, "");
_lrg_map.uf_map(i, ( lr == i ) ? j++ : _lrg_map.uf_live_range_id(lr));
}
// Now change the Node->LR mapping to reflect the compacted names
uint unique = _lrg_map.size();
for (i = 0; i < unique; i++) {
uint lrg_id = _lrg_map.live_range_id(i);
_lrg_map.map(i, _lrg_map.uf_live_range_id(lrg_id));
}
// Reset the Union-Find mapping
_lrg_map.reset_uf_map(j);
}
void PhaseChaitin::Register_Allocate() {
// Above the OLD FP (and in registers) are the incoming arguments. Stack
// slots in this area are called "arg_slots". Above the NEW FP (and in
// registers) is the outgoing argument area; above that is the spill/temp
// area. These are all "frame_slots". Arg_slots start at the zero
// stack_slots and count up to the known arg_size. Frame_slots start at
// the stack_slot #arg_size and go up. After allocation I map stack
// slots to actual offsets. Stack-slots in the arg_slot area are biased
// by the frame_size; stack-slots in the frame_slot area are biased by 0.
_trip_cnt = 0;
_alternate = 0;
_matcher._allocation_started = true;
ResourceArea split_arena(mtCompiler); // Arena for Split local resources
ResourceArea live_arena(mtCompiler); // Arena for liveness & IFG info
ResourceMark rm(&live_arena);
// Need live-ness for the IFG; need the IFG for coalescing. If the
// liveness is JUST for coalescing, then I can get some mileage by renaming
// all copy-related live ranges low and then using the max copy-related
// live range as a cut-off for LIVE and the IFG. In other words, I can
// build a subset of LIVE and IFG just for copies.
PhaseLive live(_cfg, _lrg_map.names(), &live_arena, false);
// Need IFG for coalescing and coloring
PhaseIFG ifg(&live_arena);
_ifg = &ifg;
// Come out of SSA world to the Named world. Assign (virtual) registers to
// Nodes. Use the same register for all inputs and the output of PhiNodes
// - effectively ending SSA form. This requires either coalescing live
// ranges or inserting copies. For the moment, we insert "virtual copies"
// - we pretend there is a copy prior to each Phi in predecessor blocks.
// We will attempt to coalesce such "virtual copies" before we manifest
// them for real.
de_ssa();
#ifdef ASSERT
// Verify the graph before RA.
verify(&live_arena);
#endif
{
Compile::TracePhase tp("computeLive", &timers[_t_computeLive]);
_live = NULL; // Mark live as being not available
rm.reset_to_mark(); // Reclaim working storage
IndexSet::reset_memory(C, &live_arena);
ifg.init(_lrg_map.max_lrg_id()); // Empty IFG
gather_lrg_masks( false ); // Collect LRG masks
live.compute(_lrg_map.max_lrg_id()); // Compute liveness
_live = &live; // Mark LIVE as being available
}
// Base pointers are currently "used" by instructions which define new
// derived pointers. This makes base pointers live up to the where the
// derived pointer is made, but not beyond. Really, they need to be live
// across any GC point where the derived value is live. So this code looks
// at all the GC points, and "stretches" the live range of any base pointer
// to the GC point.
if (stretch_base_pointer_live_ranges(&live_arena)) {
Compile::TracePhase tp("computeLive (sbplr)", &timers[_t_computeLive]);
// Since some live range stretched, I need to recompute live
_live = NULL;
rm.reset_to_mark(); // Reclaim working storage
IndexSet::reset_memory(C, &live_arena);
ifg.init(_lrg_map.max_lrg_id());
gather_lrg_masks(false);
live.compute(_lrg_map.max_lrg_id());
_live = &live;
}
// Create the interference graph using virtual copies
build_ifg_virtual(); // Include stack slots this time
// The IFG is/was triangular. I am 'squaring it up' so Union can run
// faster. Union requires a 'for all' operation which is slow on the
// triangular adjacency matrix (quick reminder: the IFG is 'sparse' -
// meaning I can visit all the Nodes neighbors less than a Node in time
// O(# of neighbors), but I have to visit all the Nodes greater than a
// given Node and search them for an instance, i.e., time O(#MaxLRG)).
_ifg->SquareUp();
// Aggressive (but pessimistic) copy coalescing.
// This pass works on virtual copies. Any virtual copies which are not
// coalesced get manifested as actual copies
{
Compile::TracePhase tp("chaitinCoalesce1", &timers[_t_chaitinCoalesce1]);
PhaseAggressiveCoalesce coalesce(*this);
coalesce.coalesce_driver();
// Insert un-coalesced copies. Visit all Phis. Where inputs to a Phi do
// not match the Phi itself, insert a copy.
coalesce.insert_copies(_matcher);
if (C->failing()) {
return;
}
}
// After aggressive coalesce, attempt a first cut at coloring.
// To color, we need the IFG and for that we need LIVE.
{
Compile::TracePhase tp("computeLive", &timers[_t_computeLive]);
_live = NULL;
rm.reset_to_mark(); // Reclaim working storage
IndexSet::reset_memory(C, &live_arena);
ifg.init(_lrg_map.max_lrg_id());
gather_lrg_masks( true );
live.compute(_lrg_map.max_lrg_id());
_live = &live;
}
// Build physical interference graph
uint must_spill = 0;
must_spill = build_ifg_physical(&live_arena);
// If we have a guaranteed spill, might as well spill now
if (must_spill) {
if(!_lrg_map.max_lrg_id()) {
return;
}
// Bail out if unique gets too large (ie - unique > MaxNodeLimit)
C->check_node_count(10*must_spill, "out of nodes before split");
if (C->failing()) {
return;
}
uint new_max_lrg_id = Split(_lrg_map.max_lrg_id(), &split_arena); // Split spilling LRG everywhere
_lrg_map.set_max_lrg_id(new_max_lrg_id);
// Bail out if unique gets too large (ie - unique > MaxNodeLimit - 2*NodeLimitFudgeFactor)
// or we failed to split
C->check_node_count(2*NodeLimitFudgeFactor, "out of nodes after physical split");
if (C->failing()) {
return;
}
NOT_PRODUCT(C->verify_graph_edges();)
compact(); // Compact LRGs; return new lower max lrg
{
Compile::TracePhase tp("computeLive", &timers[_t_computeLive]);
_live = NULL;
rm.reset_to_mark(); // Reclaim working storage
IndexSet::reset_memory(C, &live_arena);
ifg.init(_lrg_map.max_lrg_id()); // Build a new interference graph
gather_lrg_masks( true ); // Collect intersect mask
live.compute(_lrg_map.max_lrg_id()); // Compute LIVE
_live = &live;
}
build_ifg_physical(&live_arena);
_ifg->SquareUp();
_ifg->Compute_Effective_Degree();
// Only do conservative coalescing if requested
if (OptoCoalesce) {
Compile::TracePhase tp("chaitinCoalesce2", &timers[_t_chaitinCoalesce2]);
// Conservative (and pessimistic) copy coalescing of those spills
PhaseConservativeCoalesce coalesce(*this);
// If max live ranges greater than cutoff, don't color the stack.
// This cutoff can be larger than below since it is only done once.
coalesce.coalesce_driver();
}
_lrg_map.compress_uf_map_for_nodes();
#ifdef ASSERT
verify(&live_arena, true);
#endif
} else {
ifg.SquareUp();
ifg.Compute_Effective_Degree();
#ifdef ASSERT
set_was_low();
#endif
}
// Prepare for Simplify & Select
cache_lrg_info(); // Count degree of LRGs
// Simplify the InterFerence Graph by removing LRGs of low degree.
// LRGs of low degree are trivially colorable.
Simplify();
// Select colors by re-inserting LRGs back into the IFG in reverse order.
// Return whether or not something spills.
uint spills = Select( );
// If we spill, split and recycle the entire thing
while( spills ) {
if( _trip_cnt++ > 24 ) {
DEBUG_ONLY( dump_for_spill_split_recycle(); )
if( _trip_cnt > 27 ) {
C->record_method_not_compilable("failed spill-split-recycle sanity check");
return;
}
}
if (!_lrg_map.max_lrg_id()) {
return;
}
uint new_max_lrg_id = Split(_lrg_map.max_lrg_id(), &split_arena); // Split spilling LRG everywhere
_lrg_map.set_max_lrg_id(new_max_lrg_id);
// Bail out if unique gets too large (ie - unique > MaxNodeLimit - 2*NodeLimitFudgeFactor)
C->check_node_count(2 * NodeLimitFudgeFactor, "out of nodes after split");
if (C->failing()) {
return;
}
compact(); // Compact LRGs; return new lower max lrg
// Nuke the live-ness and interference graph and LiveRanGe info
{
Compile::TracePhase tp("computeLive", &timers[_t_computeLive]);
_live = NULL;
rm.reset_to_mark(); // Reclaim working storage
IndexSet::reset_memory(C, &live_arena);
ifg.init(_lrg_map.max_lrg_id());
// Create LiveRanGe array.
// Intersect register masks for all USEs and DEFs
gather_lrg_masks(true);
live.compute(_lrg_map.max_lrg_id());
_live = &live;
}
must_spill = build_ifg_physical(&live_arena);
_ifg->SquareUp();
_ifg->Compute_Effective_Degree();
// Only do conservative coalescing if requested
if (OptoCoalesce) {
Compile::TracePhase tp("chaitinCoalesce3", &timers[_t_chaitinCoalesce3]);
// Conservative (and pessimistic) copy coalescing
PhaseConservativeCoalesce coalesce(*this);
// Check for few live ranges determines how aggressive coalesce is.
coalesce.coalesce_driver();
}
_lrg_map.compress_uf_map_for_nodes();
#ifdef ASSERT
verify(&live_arena, true);
#endif
cache_lrg_info(); // Count degree of LRGs
// Simplify the InterFerence Graph by removing LRGs of low degree.
// LRGs of low degree are trivially colorable.
Simplify();
// Select colors by re-inserting LRGs back into the IFG in reverse order.
// Return whether or not something spills.
spills = Select();
}
// Count number of Simplify-Select trips per coloring success.
_allocator_attempts += _trip_cnt + 1;
_allocator_successes += 1;
// Peephole remove copies
post_allocate_copy_removal();
// Merge multidefs if multiple defs representing the same value are used in a single block.
merge_multidefs();
#ifdef ASSERT
// Verify the graph after RA.
verify(&live_arena);
#endif
// max_reg is past the largest *register* used.
// Convert that to a frame_slot number.
if (_max_reg <= _matcher._new_SP) {
_framesize = C->out_preserve_stack_slots();
}
else {
_framesize = _max_reg -_matcher._new_SP;
}
assert((int)(_matcher._new_SP+_framesize) >= (int)_matcher._out_arg_limit, "framesize must be large enough");
// This frame must preserve the required fp alignment
_framesize = align_up(_framesize, Matcher::stack_alignment_in_slots());
assert(_framesize <= 1000000, "sanity check");
#ifndef PRODUCT
_total_framesize += _framesize;
if ((int)_framesize > _max_framesize) {
_max_framesize = _framesize;
}
#endif
// Convert CISC spills
fixup_spills();
// Log regalloc results
CompileLog* log = Compile::current()->log();
if (log != NULL) {
log->elem("regalloc attempts='%d' success='%d'", _trip_cnt, !C->failing());
}
if (C->failing()) {
return;
}
NOT_PRODUCT(C->verify_graph_edges();)
// Move important info out of the live_arena to longer lasting storage.
alloc_node_regs(_lrg_map.size());
for (uint i=0; i < _lrg_map.size(); i++) {
if (_lrg_map.live_range_id(i)) { // Live range associated with Node?
LRG &lrg = lrgs(_lrg_map.live_range_id(i));
if (!lrg.alive()) {
set_bad(i);
} else if ((lrg.num_regs() == 1 && !lrg.is_scalable()) ||
(lrg.is_scalable() && lrg.scalable_reg_slots() == 1)) {
set1(i, lrg.reg());
} else { // Must be a register-set
if (!lrg._fat_proj) { // Must be aligned adjacent register set
// Live ranges record the highest register in their mask.
// We want the low register for the AD file writer's convenience.
OptoReg::Name hi = lrg.reg(); // Get hi register
int num_regs = lrg.num_regs();
if (lrg.is_scalable() && OptoReg::is_stack(hi)) {
// For scalable vector registers, when they are allocated in physical
// registers, num_regs is RegMask::SlotsPerVecA for reg mask of scalable
// vector. If they are allocated on stack, we need to get the actual
// num_regs, which reflects the physical length of scalable registers.
num_regs = lrg.scalable_reg_slots();
}
if (num_regs == 1) {
set1(i, hi);
} else {
OptoReg::Name lo = OptoReg::add(hi, (1 - num_regs)); // Find lo
// We have to use pair [lo,lo+1] even for wide vectors/vmasks because
// the rest of code generation works only with pairs. It is safe
// since for registers encoding only 'lo' is used.
// Second reg from pair is used in ScheduleAndBundle with vector max
// size 8 which corresponds to registers pair.
// It is also used in BuildOopMaps but oop operations are not
// vectorized.
set2(i, lo);
}
} else { // Misaligned; extract 2 bits
OptoReg::Name hi = lrg.reg(); // Get hi register
lrg.Remove(hi); // Yank from mask
int lo = lrg.mask().find_first_elem(); // Find lo
set_pair(i, hi, lo);
}
}
if( lrg._is_oop ) _node_oops.set(i);
} else {
set_bad(i);
}
}
// Done!
_live = NULL;
_ifg = NULL;
C->set_indexSet_arena(NULL); // ResourceArea is at end of scope
}
void PhaseChaitin::de_ssa() {
// Set initial Names for all Nodes. Most Nodes get the virtual register
// number. A few get the ZERO live range number. These do not
// get allocated, but instead rely on correct scheduling to ensure that
// only one instance is simultaneously live at a time.
uint lr_counter = 1;
for( uint i = 0; i < _cfg.number_of_blocks(); i++ ) {
Block* block = _cfg.get_block(i);
uint cnt = block->number_of_nodes();
// Handle all the normal Nodes in the block
for( uint j = 0; j < cnt; j++ ) {
Node *n = block->get_node(j);
// Pre-color to the zero live range, or pick virtual register
const RegMask &rm = n->out_RegMask();
_lrg_map.map(n->_idx, rm.is_NotEmpty() ? lr_counter++ : 0);
}
}
// Reset the Union-Find mapping to be identity
_lrg_map.reset_uf_map(lr_counter);
}
void PhaseChaitin::mark_ssa() {
// Use ssa names to populate the live range maps or if no mask
// is available, use the 0 entry.
uint max_idx = 0;
for ( uint i = 0; i < _cfg.number_of_blocks(); i++ ) {
Block* block = _cfg.get_block(i);
uint cnt = block->number_of_nodes();
// Handle all the normal Nodes in the block
for ( uint j = 0; j < cnt; j++ ) {
Node *n = block->get_node(j);
// Pre-color to the zero live range, or pick virtual register
const RegMask &rm = n->out_RegMask();
_lrg_map.map(n->_idx, rm.is_NotEmpty() ? n->_idx : 0);
max_idx = (n->_idx > max_idx) ? n->_idx : max_idx;
}
}
_lrg_map.set_max_lrg_id(max_idx+1);
// Reset the Union-Find mapping to be identity
_lrg_map.reset_uf_map(max_idx+1);
}
// Gather LiveRanGe information, including register masks. Modification of
// cisc spillable in_RegMasks should not be done before AggressiveCoalesce.
void PhaseChaitin::gather_lrg_masks( bool after_aggressive ) {
// Nail down the frame pointer live range
uint fp_lrg = _lrg_map.live_range_id(_cfg.get_root_node()->in(1)->in(TypeFunc::FramePtr));
lrgs(fp_lrg)._cost += 1e12; // Cost is infinite
// For all blocks
for (uint i = 0; i < _cfg.number_of_blocks(); i++) {
Block* block = _cfg.get_block(i);
// For all instructions
for (uint j = 1; j < block->number_of_nodes(); j++) {
Node* n = block->get_node(j);
uint input_edge_start =1; // Skip control most nodes
bool is_machine_node = false;
if (n->is_Mach()) {
is_machine_node = true;
input_edge_start = n->as_Mach()->oper_input_base();
}
uint idx = n->is_Copy();
// Get virtual register number, same as LiveRanGe index
uint vreg = _lrg_map.live_range_id(n);
LRG& lrg = lrgs(vreg);
if (vreg) { // No vreg means un-allocable (e.g. memory)
// Check for float-vs-int live range (used in register-pressure
// calculations)
const Type *n_type = n->bottom_type();
if (n_type->is_floatingpoint()) {
lrg._is_float = 1;
}
// Check for twice prior spilling. Once prior spilling might have
// spilled 'soft', 2nd prior spill should have spilled 'hard' and
// further spilling is unlikely to make progress.
if (_spilled_once.test(n->_idx)) {
lrg._was_spilled1 = 1;
if (_spilled_twice.test(n->_idx)) {
lrg._was_spilled2 = 1;
}
}
#ifndef PRODUCT
// Collect bits not used by product code, but which may be useful for
// debugging.
// Collect has-copy bit
if (idx) {
lrg._has_copy = 1;
uint clidx = _lrg_map.live_range_id(n->in(idx));
LRG& copy_src = lrgs(clidx);
copy_src._has_copy = 1;
}
if (trace_spilling() && lrg._def != NULL) {
// collect defs for MultiDef printing
if (lrg._defs == NULL) {
lrg._defs = new (_ifg->_arena) GrowableArray<Node*>(_ifg->_arena, 2, 0, NULL);
lrg._defs->append(lrg._def);
}
lrg._defs->append(n);
}
#endif
// Check for a single def LRG; these can spill nicely
// via rematerialization. Flag as NULL for no def found
// yet, or 'n' for single def or -1 for many defs.
lrg._def = lrg._def ? NodeSentinel : n;
// Limit result register mask to acceptable registers
const RegMask &rm = n->out_RegMask();
lrg.AND( rm );
uint ireg = n->ideal_reg();
assert( !n->bottom_type()->isa_oop_ptr() || ireg == Op_RegP,
"oops must be in Op_RegP's" );
// Check for vector live range (only if vector register is used).
// On SPARC vector uses RegD which could be misaligned so it is not
// processes as vector in RA.
if (RegMask::is_vector(ireg)) {
lrg._is_vector = 1;
if (Matcher::implements_scalable_vector && ireg == Op_VecA) {
assert(Matcher::supports_scalable_vector(), "scalable vector should be supported");
lrg._is_scalable = 1;
// For scalable vector, when it is allocated in physical register,
// num_regs is RegMask::SlotsPerVecA for reg mask,
// which may not be the actual physical register size.
// If it is allocated in stack, we need to get the actual
// physical length of scalable vector register.
lrg.set_scalable_reg_slots(Matcher::scalable_vector_reg_size(T_FLOAT));
}
}
if (ireg == Op_RegVectMask) {
assert(Matcher::has_predicated_vectors(), "predicated vector should be supported");
lrg._is_predicate = 1;
if (Matcher::supports_scalable_vector()) {
lrg._is_scalable = 1;
// For scalable predicate, when it is allocated in physical register,
// num_regs is RegMask::SlotsPerRegVectMask for reg mask,
// which may not be the actual physical register size.
// If it is allocated in stack, we need to get the actual
// physical length of scalable predicate register.
lrg.set_scalable_reg_slots(Matcher::scalable_predicate_reg_slots());
}
}
assert(n_type->isa_vect() == NULL || lrg._is_vector ||
ireg == Op_RegD || ireg == Op_RegL || ireg == Op_RegVectMask,
"vector must be in vector registers");
// Check for bound register masks
const RegMask &lrgmask = lrg.mask();
if (lrgmask.is_bound(ireg)) {
lrg._is_bound = 1;
}
// Check for maximum frequency value
if (lrg._maxfreq < block->_freq) {
lrg._maxfreq = block->_freq;
}
// Check for oop-iness, or long/double
// Check for multi-kill projection
switch (ireg) {
case MachProjNode::fat_proj:
// Fat projections have size equal to number of registers killed
lrg.set_num_regs(rm.Size());
lrg.set_reg_pressure(lrg.num_regs());
lrg._fat_proj = 1;
lrg._is_bound = 1;
break;
case Op_RegP:
#ifdef _LP64
lrg.set_num_regs(2); // Size is 2 stack words
#else
lrg.set_num_regs(1); // Size is 1 stack word
#endif
// Register pressure is tracked relative to the maximum values
// suggested for that platform, INTPRESSURE and FLOATPRESSURE,
// and relative to other types which compete for the same regs.
//
// The following table contains suggested values based on the
// architectures as defined in each .ad file.
// INTPRESSURE and FLOATPRESSURE may be tuned differently for
// compile-speed or performance.
// Note1:
// SPARC and SPARCV9 reg_pressures are at 2 instead of 1
// since .ad registers are defined as high and low halves.
// These reg_pressure values remain compatible with the code
// in is_high_pressure() which relates get_invalid_mask_size(),
// Block::_reg_pressure and INTPRESSURE, FLOATPRESSURE.
// Note2:
// SPARC -d32 has 24 registers available for integral values,
// but only 10 of these are safe for 64-bit longs.
// Using set_reg_pressure(2) for both int and long means
// the allocator will believe it can fit 26 longs into
// registers. Using 2 for longs and 1 for ints means the
// allocator will attempt to put 52 integers into registers.
// The settings below limit this problem to methods with
// many long values which are being run on 32-bit SPARC.
//
// ------------------- reg_pressure --------------------
// Each entry is reg_pressure_per_value,number_of_regs
// RegL RegI RegFlags RegF RegD INTPRESSURE FLOATPRESSURE
// IA32 2 1 1 1 1 6 6
// IA64 1 1 1 1 1 50 41
// SPARC 2 2 2 2 2 48 (24) 52 (26)
// SPARCV9 2 2 2 2 2 48 (24) 52 (26)
// AMD64 1 1 1 1 1 14 15
// -----------------------------------------------------
lrg.set_reg_pressure(1); // normally one value per register
if( n_type->isa_oop_ptr() ) {
lrg._is_oop = 1;
}
break;
case Op_RegL: // Check for long or double
case Op_RegD:
lrg.set_num_regs(2);
// Define platform specific register pressure
#if defined(ARM32)
lrg.set_reg_pressure(2);
#elif defined(IA32)
if( ireg == Op_RegL ) {
lrg.set_reg_pressure(2);
} else {
lrg.set_reg_pressure(1);
}
#else
lrg.set_reg_pressure(1); // normally one value per register
#endif
// If this def of a double forces a mis-aligned double,
// flag as '_fat_proj' - really flag as allowing misalignment
// AND changes how we count interferences. A mis-aligned
// double can interfere with TWO aligned pairs, or effectively
// FOUR registers!
if (rm.is_misaligned_pair()) {
lrg._fat_proj = 1;
lrg._is_bound = 1;
}
break;
case Op_RegVectMask:
assert(Matcher::has_predicated_vectors(), "sanity");
assert(RegMask::num_registers(Op_RegVectMask) == RegMask::SlotsPerRegVectMask, "sanity");
lrg.set_num_regs(RegMask::SlotsPerRegVectMask);
lrg.set_reg_pressure(1);
break;
case Op_RegF:
case Op_RegI:
case Op_RegN:
case Op_RegFlags:
case 0: // not an ideal register
lrg.set_num_regs(1);
lrg.set_reg_pressure(1);
break;
case Op_VecA:
assert(Matcher::supports_scalable_vector(), "does not support scalable vector");
assert(RegMask::num_registers(Op_VecA) == RegMask::SlotsPerVecA, "sanity");
assert(lrgmask.is_aligned_sets(RegMask::SlotsPerVecA), "vector should be aligned");
lrg.set_num_regs(RegMask::SlotsPerVecA);
lrg.set_reg_pressure(1);
break;
case Op_VecS:
assert(Matcher::vector_size_supported(T_BYTE,4), "sanity");
assert(RegMask::num_registers(Op_VecS) == RegMask::SlotsPerVecS, "sanity");
lrg.set_num_regs(RegMask::SlotsPerVecS);
lrg.set_reg_pressure(1);
break;
case Op_VecD:
assert(Matcher::vector_size_supported(T_FLOAT,RegMask::SlotsPerVecD), "sanity");
assert(RegMask::num_registers(Op_VecD) == RegMask::SlotsPerVecD, "sanity");
assert(lrgmask.is_aligned_sets(RegMask::SlotsPerVecD), "vector should be aligned");
lrg.set_num_regs(RegMask::SlotsPerVecD);
lrg.set_reg_pressure(1);
break;
case Op_VecX:
assert(Matcher::vector_size_supported(T_FLOAT,RegMask::SlotsPerVecX), "sanity");
assert(RegMask::num_registers(Op_VecX) == RegMask::SlotsPerVecX, "sanity");
assert(lrgmask.is_aligned_sets(RegMask::SlotsPerVecX), "vector should be aligned");
lrg.set_num_regs(RegMask::SlotsPerVecX);
lrg.set_reg_pressure(1);
break;
case Op_VecY:
assert(Matcher::vector_size_supported(T_FLOAT,RegMask::SlotsPerVecY), "sanity");
assert(RegMask::num_registers(Op_VecY) == RegMask::SlotsPerVecY, "sanity");
assert(lrgmask.is_aligned_sets(RegMask::SlotsPerVecY), "vector should be aligned");
lrg.set_num_regs(RegMask::SlotsPerVecY);
lrg.set_reg_pressure(1);
break;
case Op_VecZ:
assert(Matcher::vector_size_supported(T_FLOAT,RegMask::SlotsPerVecZ), "sanity");
assert(RegMask::num_registers(Op_VecZ) == RegMask::SlotsPerVecZ, "sanity");
assert(lrgmask.is_aligned_sets(RegMask::SlotsPerVecZ), "vector should be aligned");
lrg.set_num_regs(RegMask::SlotsPerVecZ);
lrg.set_reg_pressure(1);
break;
default:
ShouldNotReachHere();
}
}
// Now do the same for inputs
uint cnt = n->req();
// Setup for CISC SPILLING
uint inp = (uint)AdlcVMDeps::Not_cisc_spillable;
if( UseCISCSpill && after_aggressive ) {
inp = n->cisc_operand();
if( inp != (uint)AdlcVMDeps::Not_cisc_spillable )
// Convert operand number to edge index number
inp = n->as_Mach()->operand_index(inp);
}
// Prepare register mask for each input
for( uint k = input_edge_start; k < cnt; k++ ) {
uint vreg = _lrg_map.live_range_id(n->in(k));
if (!vreg) {
continue;
}
// If this instruction is CISC Spillable, add the flags
// bit to its appropriate input
if( UseCISCSpill && after_aggressive && inp == k ) {
#ifndef PRODUCT
if( TraceCISCSpill ) {
tty->print(" use_cisc_RegMask: ");
n->dump();
}
#endif
n->as_Mach()->use_cisc_RegMask();
}
if (is_machine_node && _scheduling_info_generated) {
MachNode* cur_node = n->as_Mach();
// this is cleaned up by register allocation
if (k >= cur_node->num_opnds()) continue;
}
LRG &lrg = lrgs(vreg);
// // Testing for floating point code shape
// Node *test = n->in(k);
// if( test->is_Mach() ) {
// MachNode *m = test->as_Mach();
// int op = m->ideal_Opcode();
// if (n->is_Call() && (op == Op_AddF || op == Op_MulF) ) {
// int zzz = 1;
// }
// }
// Limit result register mask to acceptable registers.
// Do not limit registers from uncommon uses before
// AggressiveCoalesce. This effectively pre-virtual-splits
// around uncommon uses of common defs.
const RegMask &rm = n->in_RegMask(k);
if (!after_aggressive && _cfg.get_block_for_node(n->in(k))->_freq > 1000 * block->_freq) {
// Since we are BEFORE aggressive coalesce, leave the register
// mask untrimmed by the call. This encourages more coalescing.
// Later, AFTER aggressive, this live range will have to spill
// but the spiller handles slow-path calls very nicely.
} else {
lrg.AND( rm );
}
// Check for bound register masks
const RegMask &lrgmask = lrg.mask();
uint kreg = n->in(k)->ideal_reg();
bool is_vect = RegMask::is_vector(kreg);
assert(n->in(k)->bottom_type()->isa_vect() == NULL || is_vect ||
kreg == Op_RegD || kreg == Op_RegL || kreg == Op_RegVectMask,
"vector must be in vector registers");
if (lrgmask.is_bound(kreg))
lrg._is_bound = 1;
// If this use of a double forces a mis-aligned double,
// flag as '_fat_proj' - really flag as allowing misalignment
// AND changes how we count interferences. A mis-aligned
// double can interfere with TWO aligned pairs, or effectively
// FOUR registers!
#ifdef ASSERT
if (is_vect && !_scheduling_info_generated) {
if (lrg.num_regs() != 0) {
assert(lrgmask.is_aligned_sets(lrg.num_regs()), "vector should be aligned");
assert(!lrg._fat_proj, "sanity");
assert(RegMask::num_registers(kreg) == lrg.num_regs(), "sanity");
} else {
assert(n->is_Phi(), "not all inputs processed only if Phi");
}
}
#endif
if (!is_vect && lrg.num_regs() == 2 && !lrg._fat_proj && rm.is_misaligned_pair()) {
lrg._fat_proj = 1;
lrg._is_bound = 1;
}
// if the LRG is an unaligned pair, we will have to spill
// so clear the LRG's register mask if it is not already spilled
if (!is_vect && !n->is_SpillCopy() &&
(lrg._def == NULL || lrg.is_multidef() || !lrg._def->is_SpillCopy()) &&
lrgmask.is_misaligned_pair()) {
lrg.Clear();
}
// Check for maximum frequency value
if (lrg._maxfreq < block->_freq) {
lrg._maxfreq = block->_freq;
}
} // End for all allocated inputs
} // end for all instructions
} // end for all blocks
// Final per-liverange setup
for (uint i2 = 0; i2 < _lrg_map.max_lrg_id(); i2++) {
LRG &lrg = lrgs(i2);
assert(!lrg._is_vector || !lrg._fat_proj, "sanity");
if (lrg.num_regs() > 1 && !lrg._fat_proj) {
lrg.clear_to_sets();
}
lrg.compute_set_mask_size();
if (lrg.not_free()) { // Handle case where we lose from the start
lrg.set_reg(OptoReg::Name(LRG::SPILL_REG));
lrg._direct_conflict = 1;
}
lrg.set_degree(0); // no neighbors in IFG yet
}
}
// Set the was-lo-degree bit. Conservative coalescing should not change the
// colorability of the graph. If any live range was of low-degree before
// coalescing, it should Simplify. This call sets the was-lo-degree bit.
// The bit is checked in Simplify.
void PhaseChaitin::set_was_low() {
#ifdef ASSERT
for (uint i = 1; i < _lrg_map.max_lrg_id(); i++) {
int size = lrgs(i).num_regs();
uint old_was_lo = lrgs(i)._was_lo;
lrgs(i)._was_lo = 0;
if( lrgs(i).lo_degree() ) {
lrgs(i)._was_lo = 1; // Trivially of low degree
} else { // Else check the Brigg's assertion
// Brigg's observation is that the lo-degree neighbors of a
// hi-degree live range will not interfere with the color choices
// of said hi-degree live range. The Simplify reverse-stack-coloring
// order takes care of the details. Hence you do not have to count
// low-degree neighbors when determining if this guy colors.
int briggs_degree = 0;
IndexSet *s = _ifg->neighbors(i);
IndexSetIterator elements(s);
uint lidx;
while((lidx = elements.next()) != 0) {
if( !lrgs(lidx).lo_degree() )
briggs_degree += MAX2(size,lrgs(lidx).num_regs());
}
if( briggs_degree < lrgs(i).degrees_of_freedom() )
lrgs(i)._was_lo = 1; // Low degree via the briggs assertion
}
assert(old_was_lo <= lrgs(i)._was_lo, "_was_lo may not decrease");
}
#endif
}
// Compute cost/area ratio, in case we spill. Build the lo-degree list.
void PhaseChaitin::cache_lrg_info( ) {
Compile::TracePhase tp("chaitinCacheLRG", &timers[_t_chaitinCacheLRG]);
for (uint i = 1; i < _lrg_map.max_lrg_id(); i++) {
LRG &lrg = lrgs(i);
// Check for being of low degree: means we can be trivially colored.
// Low degree, dead or must-spill guys just get to simplify right away
if( lrg.lo_degree() ||
!lrg.alive() ||
lrg._must_spill ) {
// Split low degree list into those guys that must get a
// register and those that can go to register or stack.
// The idea is LRGs that can go register or stack color first when
// they have a good chance of getting a register. The register-only
// lo-degree live ranges always get a register.
OptoReg::Name hi_reg = lrg.mask().find_last_elem();
if( OptoReg::is_stack(hi_reg)) { // Can go to stack?
lrg._next = _lo_stk_degree;
_lo_stk_degree = i;
} else {
lrg._next = _lo_degree;
_lo_degree = i;
}
} else { // Else high degree
lrgs(_hi_degree)._prev = i;
lrg._next = _hi_degree;
lrg._prev = 0;
_hi_degree = i;
}
}
}
// Simplify the IFG by removing LRGs of low degree.
void PhaseChaitin::Simplify( ) {
Compile::TracePhase tp("chaitinSimplify", &timers[_t_chaitinSimplify]);
while( 1 ) { // Repeat till simplified it all
// May want to explore simplifying lo_degree before _lo_stk_degree.
// This might result in more spills coloring into registers during
// Select().
while( _lo_degree || _lo_stk_degree ) {
// If possible, pull from lo_stk first
uint lo;
if( _lo_degree ) {
lo = _lo_degree;
_lo_degree = lrgs(lo)._next;
} else {
lo = _lo_stk_degree;
_lo_stk_degree = lrgs(lo)._next;
}
// Put the simplified guy on the simplified list.
lrgs(lo)._next = _simplified;
_simplified = lo;
// If this guy is "at risk" then mark his current neighbors
if (lrgs(lo)._at_risk && !_ifg->neighbors(lo)->is_empty()) {
IndexSetIterator elements(_ifg->neighbors(lo));
uint datum;
while ((datum = elements.next()) != 0) {
lrgs(datum)._risk_bias = lo;
}
}
// Yank this guy from the IFG.
IndexSet *adj = _ifg->remove_node(lo);
if (adj->is_empty()) {
continue;
}
// If any neighbors' degrees fall below their number of
// allowed registers, then put that neighbor on the low degree
// list. Note that 'degree' can only fall and 'numregs' is
// unchanged by this action. Thus the two are equal at most once,
// so LRGs hit the lo-degree worklist at most once.
IndexSetIterator elements(adj);
uint neighbor;
while ((neighbor = elements.next()) != 0) {
LRG *n = &lrgs(neighbor);
#ifdef ASSERT
if (VerifyRegisterAllocator) {
assert( _ifg->effective_degree(neighbor) == n->degree(), "" );
}
#endif
// Check for just becoming of-low-degree just counting registers.
// _must_spill live ranges are already on the low degree list.
if (n->just_lo_degree() && !n->_must_spill) {
assert(!_ifg->_yanked->test(neighbor), "Cannot move to lo degree twice");
// Pull from hi-degree list
uint prev = n->_prev;
uint next = n->_next;
if (prev) {
lrgs(prev)._next = next;
} else {
_hi_degree = next;
}
lrgs(next)._prev = prev;
n->_next = _lo_degree;
_lo_degree = neighbor;
}
}
} // End of while lo-degree/lo_stk_degree worklist not empty
// Check for got everything: is hi-degree list empty?
if (!_hi_degree) break;
// Time to pick a potential spill guy
uint lo_score = _hi_degree;
double score = lrgs(lo_score).score();
double area = lrgs(lo_score)._area;
double cost = lrgs(lo_score)._cost;
bool bound = lrgs(lo_score)._is_bound;
// Find cheapest guy
debug_only( int lo_no_simplify=0; );
for (uint i = _hi_degree; i; i = lrgs(i)._next) {
assert(!_ifg->_yanked->test(i), "");
// It's just vaguely possible to move hi-degree to lo-degree without
// going through a just-lo-degree stage: If you remove a double from
// a float live range it's degree will drop by 2 and you can skip the
// just-lo-degree stage. It's very rare (shows up after 5000+ methods
// in -Xcomp of Java2Demo). So just choose this guy to simplify next.
if( lrgs(i).lo_degree() ) {
lo_score = i;
break;
}
debug_only( if( lrgs(i)._was_lo ) lo_no_simplify=i; );
double iscore = lrgs(i).score();
double iarea = lrgs(i)._area;
double icost = lrgs(i)._cost;
bool ibound = lrgs(i)._is_bound;
// Compare cost/area of i vs cost/area of lo_score. Smaller cost/area
// wins. Ties happen because all live ranges in question have spilled
// a few times before and the spill-score adds a huge number which
// washes out the low order bits. We are choosing the lesser of 2
// evils; in this case pick largest area to spill.
// Ties also happen when live ranges are defined and used only inside
// one block. In which case their area is 0 and score set to max.
// In such case choose bound live range over unbound to free registers
// or with smaller cost to spill.
if ( iscore < score ||
(iscore == score && iarea > area && lrgs(lo_score)._was_spilled2) ||
(iscore == score && iarea == area &&
( (ibound && !bound) || (ibound == bound && (icost < cost)) )) ) {
lo_score = i;
score = iscore;
area = iarea;
cost = icost;
bound = ibound;
}
}
LRG *lo_lrg = &lrgs(lo_score);
// The live range we choose for spilling is either hi-degree, or very
// rarely it can be low-degree. If we choose a hi-degree live range
// there better not be any lo-degree choices.
assert( lo_lrg->lo_degree() || !lo_no_simplify, "Live range was lo-degree before coalesce; should simplify" );
// Pull from hi-degree list
uint prev = lo_lrg->_prev;
uint next = lo_lrg->_next;
if( prev ) lrgs(prev)._next = next;
else _hi_degree = next;
lrgs(next)._prev = prev;
// Jam him on the lo-degree list, despite his high degree.
// Maybe he'll get a color, and maybe he'll spill.
// Only Select() will know.
lrgs(lo_score)._at_risk = true;
_lo_degree = lo_score;
lo_lrg->_next = 0;
} // End of while not simplified everything
}
// Is 'reg' register legal for 'lrg'?
static bool is_legal_reg(LRG &lrg, OptoReg::Name reg, int chunk) {
if (reg >= chunk && reg < (chunk + RegMask::CHUNK_SIZE) &&
lrg.mask().Member(OptoReg::add(reg,-chunk))) {
// RA uses OptoReg which represent the highest element of a registers set.
// For example, vectorX (128bit) on x86 uses [XMM,XMMb,XMMc,XMMd] set
// in which XMMd is used by RA to represent such vectors. A double value
// uses [XMM,XMMb] pairs and XMMb is used by RA for it.
// The register mask uses largest bits set of overlapping register sets.
// On x86 with AVX it uses 8 bits for each XMM registers set.
//
// The 'lrg' already has cleared-to-set register mask (done in Select()
// before calling choose_color()). Passing mask.Member(reg) check above
// indicates that the size (num_regs) of 'reg' set is less or equal to
// 'lrg' set size.
// For set size 1 any register which is member of 'lrg' mask is legal.
if (lrg.num_regs()==1)
return true;
// For larger sets only an aligned register with the same set size is legal.
int mask = lrg.num_regs()-1;
if ((reg&mask) == mask)
return true;
}
return false;
}
static OptoReg::Name find_first_set(LRG &lrg, RegMask mask, int chunk) {
int num_regs = lrg.num_regs();
OptoReg::Name assigned = mask.find_first_set(lrg, num_regs);
if (lrg.is_scalable()) {
// a physical register is found
if (chunk == 0 && OptoReg::is_reg(assigned)) {
return assigned;
}
// find available stack slots for scalable register
if (lrg._is_vector) {
num_regs = lrg.scalable_reg_slots();
// if actual scalable vector register is exactly SlotsPerVecA * 32 bits
if (num_regs == RegMask::SlotsPerVecA) {
return assigned;
}
// mask has been cleared out by clear_to_sets(SlotsPerVecA) before choose_color, but it
// does not work for scalable size. We have to find adjacent scalable_reg_slots() bits
// instead of SlotsPerVecA bits.
assigned = mask.find_first_set(lrg, num_regs); // find highest valid reg
while (OptoReg::is_valid(assigned) && RegMask::can_represent(assigned)) {
// Verify the found reg has scalable_reg_slots() bits set.
if (mask.is_valid_reg(assigned, num_regs)) {
return assigned;
} else {
// Remove more for each iteration
mask.Remove(assigned - num_regs + 1); // Unmask the lowest reg
mask.clear_to_sets(RegMask::SlotsPerVecA); // Align by SlotsPerVecA bits
assigned = mask.find_first_set(lrg, num_regs);
}
}
return OptoReg::Bad; // will cause chunk change, and retry next chunk
} else if (lrg._is_predicate) {
assert(num_regs == RegMask::SlotsPerRegVectMask, "scalable predicate register");
num_regs = lrg.scalable_reg_slots();
mask.clear_to_sets(num_regs);
return mask.find_first_set(lrg, num_regs);
}
}
return assigned;
}
// Choose a color using the biasing heuristic
OptoReg::Name PhaseChaitin::bias_color( LRG &lrg, int chunk ) {
// Check for "at_risk" LRG's
uint risk_lrg = _lrg_map.find(lrg._risk_bias);
if (risk_lrg != 0 && !_ifg->neighbors(risk_lrg)->is_empty()) {
// Walk the colored neighbors of the "at_risk" candidate
// Choose a color which is both legal and already taken by a neighbor
// of the "at_risk" candidate in order to improve the chances of the
// "at_risk" candidate of coloring
IndexSetIterator elements(_ifg->neighbors(risk_lrg));
uint datum;
while ((datum = elements.next()) != 0) {
OptoReg::Name reg = lrgs(datum).reg();
// If this LRG's register is legal for us, choose it
if (is_legal_reg(lrg, reg, chunk))
return reg;
}
}
uint copy_lrg = _lrg_map.find(lrg._copy_bias);
if (copy_lrg != 0) {
// If he has a color,
if(!_ifg->_yanked->test(copy_lrg)) {
OptoReg::Name reg = lrgs(copy_lrg).reg();
// And it is legal for you,
if (is_legal_reg(lrg, reg, chunk))
return reg;
} else if( chunk == 0 ) {
// Choose a color which is legal for him
RegMask tempmask = lrg.mask();
tempmask.AND(lrgs(copy_lrg).mask());
tempmask.clear_to_sets(lrg.num_regs());
OptoReg::Name reg = find_first_set(lrg, tempmask, chunk);
if (OptoReg::is_valid(reg))
return reg;
}
}
// If no bias info exists, just go with the register selection ordering
if (lrg._is_vector || lrg.num_regs() == 2 || lrg.is_scalable()) {
// Find an aligned set
return OptoReg::add(find_first_set(lrg, lrg.mask(), chunk), chunk);
}
// CNC - Fun hack. Alternate 1st and 2nd selection. Enables post-allocate
// copy removal to remove many more copies, by preventing a just-assigned
// register from being repeatedly assigned.
OptoReg::Name reg = lrg.mask().find_first_elem();
if( (++_alternate & 1) && OptoReg::is_valid(reg) ) {
// This 'Remove; find; Insert' idiom is an expensive way to find the
// SECOND element in the mask.
lrg.Remove(reg);
OptoReg::Name reg2 = lrg.mask().find_first_elem();
lrg.Insert(reg);
if( OptoReg::is_reg(reg2))
reg = reg2;
}
return OptoReg::add( reg, chunk );
}
// Choose a color in the current chunk
OptoReg::Name PhaseChaitin::choose_color( LRG &lrg, int chunk ) {
assert( C->in_preserve_stack_slots() == 0 || chunk != 0 || lrg._is_bound || lrg.mask().is_bound1() || !lrg.mask().Member(OptoReg::Name(_matcher._old_SP-1)), "must not allocate stack0 (inside preserve area)");
assert(C->out_preserve_stack_slots() == 0 || chunk != 0 || lrg._is_bound || lrg.mask().is_bound1() || !lrg.mask().Member(OptoReg::Name(_matcher._old_SP+0)), "must not allocate stack0 (inside preserve area)");
if( lrg.num_regs() == 1 || // Common Case
!lrg._fat_proj ) // Aligned+adjacent pairs ok
// Use a heuristic to "bias" the color choice
return bias_color(lrg, chunk);
assert(!lrg._is_vector, "should be not vector here" );
assert( lrg.num_regs() >= 2, "dead live ranges do not color" );
// Fat-proj case or misaligned double argument.
assert(lrg.compute_mask_size() == lrg.num_regs() ||
lrg.num_regs() == 2,"fat projs exactly color" );
assert( !chunk, "always color in 1st chunk" );
// Return the highest element in the set.
return lrg.mask().find_last_elem();
}
// Select colors by re-inserting LRGs back into the IFG. LRGs are re-inserted
// in reverse order of removal. As long as nothing of hi-degree was yanked,
// everything going back is guaranteed a color. Select that color. If some
// hi-degree LRG cannot get a color then we record that we must spill.
uint PhaseChaitin::Select( ) {
Compile::TracePhase tp("chaitinSelect", &timers[_t_chaitinSelect]);
uint spill_reg = LRG::SPILL_REG;
_max_reg = OptoReg::Name(0); // Past max register used
while( _simplified ) {
// Pull next LRG from the simplified list - in reverse order of removal
uint lidx = _simplified;
LRG *lrg = &lrgs(lidx);
_simplified = lrg->_next;
#ifndef PRODUCT
if (trace_spilling()) {
ttyLocker ttyl;
tty->print_cr("L%d selecting degree %d degrees_of_freedom %d", lidx, lrg->degree(),
lrg->degrees_of_freedom());
lrg->dump();
}
#endif
// Re-insert into the IFG
_ifg->re_insert(lidx);
if( !lrg->alive() ) continue;
// capture allstackedness flag before mask is hacked
const int is_allstack = lrg->mask().is_AllStack();
// Yeah, yeah, yeah, I know, I know. I can refactor this
// to avoid the GOTO, although the refactored code will not
// be much clearer. We arrive here IFF we have a stack-based
// live range that cannot color in the current chunk, and it
// has to move into the next free stack chunk.
int chunk = 0; // Current chunk is first chunk
retry_next_chunk:
// Remove neighbor colors
IndexSet *s = _ifg->neighbors(lidx);
debug_only(RegMask orig_mask = lrg->mask();)
if (!s->is_empty()) {
IndexSetIterator elements(s);
uint neighbor;
while ((neighbor = elements.next()) != 0) {
// Note that neighbor might be a spill_reg. In this case, exclusion
// of its color will be a no-op, since the spill_reg chunk is in outer
// space. Also, if neighbor is in a different chunk, this exclusion
// will be a no-op. (Later on, if lrg runs out of possible colors in
// its chunk, a new chunk of color may be tried, in which case
// examination of neighbors is started again, at retry_next_chunk.)
LRG &nlrg = lrgs(neighbor);
OptoReg::Name nreg = nlrg.reg();
// Only subtract masks in the same chunk
if (nreg >= chunk && nreg < chunk + RegMask::CHUNK_SIZE) {
#ifndef PRODUCT
uint size = lrg->mask().Size();
RegMask rm = lrg->mask();
#endif
lrg->SUBTRACT(nlrg.mask());
#ifndef PRODUCT
if (trace_spilling() && lrg->mask().Size() != size) {
ttyLocker ttyl;
tty->print("L%d ", lidx);
rm.dump();
tty->print(" intersected L%d ", neighbor);
nlrg.mask().dump();
tty->print(" removed ");
rm.SUBTRACT(lrg->mask());
rm.dump();
tty->print(" leaving ");
lrg->mask().dump();
tty->cr();
}
#endif
}
}
}
//assert(is_allstack == lrg->mask().is_AllStack(), "nbrs must not change AllStackedness");
// Aligned pairs need aligned masks
assert(!lrg->_is_vector || !lrg->_fat_proj, "sanity");
if (lrg->num_regs() > 1 && !lrg->_fat_proj) {
lrg->clear_to_sets();
}
// Check if a color is available and if so pick the color
OptoReg::Name reg = choose_color( *lrg, chunk );
//---------------
// If we fail to color and the AllStack flag is set, trigger
// a chunk-rollover event
if(!OptoReg::is_valid(OptoReg::add(reg,-chunk)) && is_allstack) {
// Bump register mask up to next stack chunk
chunk += RegMask::CHUNK_SIZE;
lrg->Set_All();
goto retry_next_chunk;
}
//---------------
// Did we get a color?
else if( OptoReg::is_valid(reg)) {
#ifndef PRODUCT
RegMask avail_rm = lrg->mask();
#endif
// Record selected register
lrg->set_reg(reg);
if( reg >= _max_reg ) // Compute max register limit
_max_reg = OptoReg::add(reg,1);
// Fold reg back into normal space
reg = OptoReg::add(reg,-chunk);
// If the live range is not bound, then we actually had some choices
// to make. In this case, the mask has more bits in it than the colors
// chosen. Restrict the mask to just what was picked.
int n_regs = lrg->num_regs();
assert(!lrg->_is_vector || !lrg->_fat_proj, "sanity");
if (n_regs == 1 || !lrg->_fat_proj) {
if (Matcher::supports_scalable_vector()) {
assert(!lrg->_is_vector || n_regs <= RegMask::SlotsPerVecA, "sanity");
} else {
assert(!lrg->_is_vector || n_regs <= RegMask::SlotsPerVecZ, "sanity");
}
lrg->Clear(); // Clear the mask
lrg->Insert(reg); // Set regmask to match selected reg
// For vectors and pairs, also insert the low bit of the pair
// We always choose the high bit, then mask the low bits by register size
if (lrg->is_scalable() && OptoReg::is_stack(lrg->reg())) { // stack
n_regs = lrg->scalable_reg_slots();
}
for (int i = 1; i < n_regs; i++) {
lrg->Insert(OptoReg::add(reg,-i));
}
lrg->set_mask_size(n_regs);
} else { // Else fatproj
// mask must be equal to fatproj bits, by definition
}
#ifndef PRODUCT
if (trace_spilling()) {
ttyLocker ttyl;
tty->print("L%d selected ", lidx);
lrg->mask().dump();
tty->print(" from ");
avail_rm.dump();
tty->cr();
}
#endif
// Note that reg is the highest-numbered register in the newly-bound mask.
} // end color available case
//---------------
// Live range is live and no colors available
else {
assert( lrg->alive(), "" );
assert( !lrg->_fat_proj || lrg->is_multidef() ||
lrg->_def->outcnt() > 0, "fat_proj cannot spill");
assert( !orig_mask.is_AllStack(), "All Stack does not spill" );
// Assign the special spillreg register
lrg->set_reg(OptoReg::Name(spill_reg++));
// Do not empty the regmask; leave mask_size lying around
// for use during Spilling
#ifndef PRODUCT
if( trace_spilling() ) {
ttyLocker ttyl;
tty->print("L%d spilling with neighbors: ", lidx);
s->dump();
debug_only(tty->print(" original mask: "));
debug_only(orig_mask.dump());
dump_lrg(lidx);
}
#endif
} // end spill case
}
return spill_reg-LRG::SPILL_REG; // Return number of spills
}
// Set the 'spilled_once' or 'spilled_twice' flag on a node.
void PhaseChaitin::set_was_spilled( Node *n ) {
if( _spilled_once.test_set(n->_idx) )
_spilled_twice.set(n->_idx);
}
// Convert Ideal spill instructions into proper FramePtr + offset Loads and
// Stores. Use-def chains are NOT preserved, but Node->LRG->reg maps are.
void PhaseChaitin::fixup_spills() {
// This function does only cisc spill work.
if( !UseCISCSpill ) return;
Compile::TracePhase tp("fixupSpills", &timers[_t_fixupSpills]);
// Grab the Frame Pointer
Node *fp = _cfg.get_root_block()->head()->in(1)->in(TypeFunc::FramePtr);
// For all blocks
for (uint i = 0; i < _cfg.number_of_blocks(); i++) {
Block* block = _cfg.get_block(i);
// For all instructions in block
uint last_inst = block->end_idx();
for (uint j = 1; j <= last_inst; j++) {
Node* n = block->get_node(j);
// Dead instruction???
assert( n->outcnt() != 0 ||// Nothing dead after post alloc
C->top() == n || // Or the random TOP node
n->is_Proj(), // Or a fat-proj kill node
"No dead instructions after post-alloc" );
int inp = n->cisc_operand();
if( inp != AdlcVMDeps::Not_cisc_spillable ) {
// Convert operand number to edge index number
MachNode *mach = n->as_Mach();
inp = mach->operand_index(inp);
Node *src = n->in(inp); // Value to load or store
--> --------------------
--> maximum size reached
--> --------------------
¤ Dauer der Verarbeitung: 0.125 Sekunden
(vorverarbeitet)
¤
|
Haftungshinweis
Die Informationen auf dieser Webseite wurden
nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit,
noch Qualität der bereit gestellten Informationen zugesichert.
Bemerkung:
Die farbliche Syntaxdarstellung ist noch experimentell.
|
