JDK14/Java14源码在线阅读
/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* This code is free software; you can redistribute it and/or modify it
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*
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* version 2 for more details (a copy is included in the LICENSE file that
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#include "precompiled.hpp"
#include "libadt/vectset.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.inline.hpp"
#include "opto/addnode.hpp"
#include "opto/c2compiler.hpp"
#include "opto/callnode.hpp"
#include "opto/cfgnode.hpp"
#include "opto/chaitin.hpp"
#include "opto/loopnode.hpp"
#include "opto/machnode.hpp"
//------------------------------Split--------------------------------------
// Walk the graph in RPO and for each lrg which spills, propagate reaching
// definitions. During propagation, split the live range around regions of
// High Register Pressure (HRP). If a Def is in a region of Low Register
// Pressure (LRP), it will not get spilled until we encounter a region of
// HRP between it and one of its uses. We will spill at the transition
// point between LRP and HRP. Uses in the HRP region will use the spilled
// Def. The first Use outside the HRP region will generate a SpillCopy to
// hoist the live range back up into a register, and all subsequent uses
// will use that new Def until another HRP region is encountered. Defs in
// HRP regions will get trailing SpillCopies to push the LRG down into the
// stack immediately.
//
// As a side effect, unlink from (hence make dead) coalesced copies.
//
static const char out_of_nodes[] = "out of nodes during split";
//------------------------------get_spillcopy_wide-----------------------------
// Get a SpillCopy node with wide-enough masks. Use the 'wide-mask', the
// wide ideal-register spill-mask if possible. If the 'wide-mask' does
// not cover the input (or output), use the input (or output) mask instead.
Node *PhaseChaitin::get_spillcopy_wide(MachSpillCopyNode::SpillType spill_type, Node *def, Node *use, uint uidx) {
// If ideal reg doesn't exist we've got a bad schedule happening
// that is forcing us to spill something that isn't spillable.
// Bail rather than abort
uint ireg = def->ideal_reg();
if (ireg == 0 || ireg == Op_RegFlags) {
assert(false, "attempted to spill a non-spillable item: %d: %s <- %d: %s, ireg = %u, spill_type: %s",
def->_idx, def->Name(), use->_idx, use->Name(), ireg,
MachSpillCopyNode::spill_type(spill_type));
C->record_method_not_compilable("attempted to spill a non-spillable item");
return NULL;
}
if (C->check_node_count(NodeLimitFudgeFactor, out_of_nodes)) {
return NULL;
}
const RegMask *i_mask = &def->out_RegMask();
const RegMask *w_mask = C->matcher()->idealreg2spillmask[ireg];
const RegMask *o_mask = use ? &use->in_RegMask(uidx) : w_mask;
const RegMask *w_i_mask = w_mask->overlap( *i_mask ) ? w_mask : i_mask;
const RegMask *w_o_mask;
int num_regs = RegMask::num_registers(ireg);
bool is_vect = RegMask::is_vector(ireg);
if( w_mask->overlap( *o_mask ) && // Overlap AND
(num_regs == 1 // Single use or aligned
|| is_vect // or vector
|| (!is_vect && o_mask->is_aligned_pairs())) ) {
assert(!is_vect || o_mask->is_aligned_sets(num_regs), "vectors are aligned");
// Don't come here for mis-aligned doubles
w_o_mask = w_mask;
} else { // wide ideal mask does not overlap with o_mask
// Mis-aligned doubles come here and XMM->FPR moves on x86.
w_o_mask = o_mask; // Must target desired registers
// Does the ideal-reg-mask overlap with o_mask? I.e., can I use
// a reg-reg move or do I need a trip across register classes
// (and thus through memory)?
if( !C->matcher()->idealreg2regmask[ireg]->overlap( *o_mask) && o_mask->is_UP() )
// Here we assume a trip through memory is required.
w_i_mask = &C->FIRST_STACK_mask();
}
return new MachSpillCopyNode(spill_type, def, *w_i_mask, *w_o_mask );
}
//------------------------------insert_proj------------------------------------
// Insert the spill at chosen location. Skip over any intervening Proj's or
// Phis. Skip over a CatchNode and projs, inserting in the fall-through block
// instead. Update high-pressure indices. Create a new live range.
void PhaseChaitin::insert_proj( Block *b, uint i, Node *spill, uint maxlrg ) {
// Skip intervening ProjNodes. Do not insert between a ProjNode and
// its definer.
while( i < b->number_of_nodes() &&
(b->get_node(i)->is_Proj() ||
b->get_node(i)->is_Phi() ) )
i++;
// Do not insert between a call and his Catch
if( b->get_node(i)->is_Catch() ) {
// Put the instruction at the top of the fall-thru block.
// Find the fall-thru projection
while( 1 ) {
const CatchProjNode *cp = b->get_node(++i)->as_CatchProj();
if( cp->_con == CatchProjNode::fall_through_index )
break;
}
int sidx = i - b->end_idx()-1;
b = b->_succs[sidx]; // Switch to successor block
i = 1; // Right at start of block
}
b->insert_node(spill, i); // Insert node in block
_cfg.map_node_to_block(spill, b); // Update node->block mapping to reflect
// Adjust the point where we go hi-pressure
if( i <= b->_ihrp_index ) b->_ihrp_index++;
if( i <= b->_fhrp_index ) b->_fhrp_index++;
// Assign a new Live Range Number to the SpillCopy and grow
// the node->live range mapping.
new_lrg(spill,maxlrg);
}
//------------------------------split_DEF--------------------------------------
// There are four categories of Split; UP/DOWN x DEF/USE
// Only three of these really occur as DOWN/USE will always color
// Any Split with a DEF cannot CISC-Spill now. Thus we need
// two helper routines, one for Split DEFS (insert after instruction),
// one for Split USES (insert before instruction). DEF insertion
// happens inside Split, where the Leaveblock array is updated.
uint PhaseChaitin::split_DEF( Node *def, Block *b, int loc, uint maxlrg, Node **Reachblock, Node **debug_defs, GrowableArray<uint> splits, int slidx ) {
#ifdef ASSERT
// Increment the counter for this lrg
splits.at_put(slidx, splits.at(slidx)+1);
#endif
// If we are spilling the memory op for an implicit null check, at the
// null check location (ie - null check is in HRP block) we need to do
// the null-check first, then spill-down in the following block.
// (The implicit_null_check function ensures the use is also dominated
// by the branch-not-taken block.)
Node *be = b->end();
if( be->is_MachNullCheck() && be->in(1) == def && def == b->get_node(loc)) {
// Spill goes in the branch-not-taken block
b = b->_succs[b->get_node(b->end_idx()+1)->Opcode() == Op_IfTrue];
loc = 0; // Just past the Region
}
assert( loc >= 0, "must insert past block head" );
// Get a def-side SpillCopy
Node *spill = get_spillcopy_wide(MachSpillCopyNode::Definition, def, NULL, 0);
// Did we fail to split?, then bail
if (!spill) {
return 0;
}
// Insert the spill at chosen location
insert_proj( b, loc+1, spill, maxlrg++);
// Insert new node into Reaches array
Reachblock[slidx] = spill;
// Update debug list of reaching down definitions by adding this one
debug_defs[slidx] = spill;
// return updated count of live ranges
return maxlrg;
}
//------------------------------split_USE--------------------------------------
// Splits at uses can involve redeffing the LRG, so no CISC Spilling there.
// Debug uses want to know if def is already stack enabled.
uint PhaseChaitin::split_USE(MachSpillCopyNode::SpillType spill_type, Node *def, Block *b, Node *use, uint useidx, uint maxlrg, bool def_down, bool cisc_sp, GrowableArray<uint> splits, int slidx ) {
#ifdef ASSERT
// Increment the counter for this lrg
splits.at_put(slidx, splits.at(slidx)+1);
#endif
// Some setup stuff for handling debug node uses
JVMState* jvms = use->jvms();
uint debug_start = jvms ? jvms->debug_start() : 999999;
uint debug_end = jvms ? jvms->debug_end() : 999999;
//-------------------------------------------
// Check for use of debug info
if (useidx >= debug_start && useidx < debug_end) {
// Actually it's perfectly legal for constant debug info to appear
// just unlikely. In this case the optimizer left a ConI of a 4
// as both inputs to a Phi with only a debug use. It's a single-def
// live range of a rematerializable value. The live range spills,
// rematerializes and now the ConI directly feeds into the debug info.
// assert(!def->is_Con(), "constant debug info already constructed directly");
// Special split handling for Debug Info
// If DEF is DOWN, just hook the edge and return
// If DEF is UP, Split it DOWN for this USE.
if( def->is_Mach() ) {
if( def_down ) {
// DEF is DOWN, so connect USE directly to the DEF
use->set_req(useidx, def);
} else {
// Block and index where the use occurs.
Block *b = _cfg.get_block_for_node(use);
// Put the clone just prior to use
int bindex = b->find_node(use);
// DEF is UP, so must copy it DOWN and hook in USE
// Insert SpillCopy before the USE, which uses DEF as its input,
// and defs a new live range, which is used by this node.
Node *spill = get_spillcopy_wide(spill_type, def,use,useidx);
// did we fail to split?
if (!spill) {
// Bail
return 0;
}
// insert into basic block
insert_proj( b, bindex, spill, maxlrg++ );
// Use the new split
use->set_req(useidx,spill);
}
// No further split handling needed for this use
return maxlrg;
} // End special splitting for debug info live range
} // If debug info
// CISC-SPILLING
// Finally, check to see if USE is CISC-Spillable, and if so,
// gather_lrg_masks will add the flags bit to its mask, and
// no use side copy is needed. This frees up the live range
// register choices without causing copy coalescing, etc.
if( UseCISCSpill && cisc_sp ) {
int inp = use->cisc_operand();
if( inp != AdlcVMDeps::Not_cisc_spillable )
// Convert operand number to edge index number
inp = use->as_Mach()->operand_index(inp);
if( inp == (int)useidx ) {
use->set_req(useidx, def);
#ifndef PRODUCT
if( TraceCISCSpill ) {
tty->print(" set_split: ");
use->dump();
}
#endif
return maxlrg;
}
}
//-------------------------------------------
// Insert a Copy before the use
// Block and index where the use occurs.
int bindex;
// Phi input spill-copys belong at the end of the prior block
if( use->is_Phi() ) {
b = _cfg.get_block_for_node(b->pred(useidx));
bindex = b->end_idx();
} else {
// Put the clone just prior to use
bindex = b->find_node(use);
}
Node *spill = get_spillcopy_wide(spill_type, def, use, useidx );
if( !spill ) return 0; // Bailed out
// Insert SpillCopy before the USE, which uses the reaching DEF as
// its input, and defs a new live range, which is used by this node.
insert_proj( b, bindex, spill, maxlrg++ );
// Use the spill/clone
use->set_req(useidx,spill);
// return updated live range count
return maxlrg;
}
//------------------------------clone_node----------------------------
// Clone node with anti dependence check.
Node* clone_node(Node* def, Block *b, Compile* C) {
if (def->needs_anti_dependence_check()) {
#ifdef ASSERT
if (PrintOpto && WizardMode) {
tty->print_cr("RA attempts to clone node with anti_dependence:");
def->dump(-1); tty->cr();
tty->print_cr("into block:");
b->dump();
}
#endif
if (C->subsume_loads() == true && !C->failing()) {
// Retry with subsume_loads == false
// If this is the first failure, the sentinel string will "stick"
// to the Compile object, and the C2Compiler will see it and retry.
C->record_failure(C2Compiler::retry_no_subsuming_loads());
} else {
// Bailout without retry
C->record_method_not_compilable("RA Split failed: attempt to clone node with anti_dependence");
}
return 0;
}
return def->clone();
}
//------------------------------split_Rematerialize----------------------------
// Clone a local copy of the def.
Node *PhaseChaitin::split_Rematerialize(Node *def, Block *b, uint insidx, uint &maxlrg,
GrowableArray<uint> splits, int slidx, uint *lrg2reach,
Node **Reachblock, bool walkThru) {
// The input live ranges will be stretched to the site of the new
// instruction. They might be stretched past a def and will thus
// have the old and new values of the same live range alive at the
// same time - a definite no-no. Split out private copies of
// the inputs.
if (def->req() > 1) {
for (uint i = 1; i < def->req(); i++) {
Node *in = def->in(i);
uint lidx = _lrg_map.live_range_id(in);
// We do not need this for live ranges that are only defined once.
// However, this is not true for spill copies that are added in this
// Split() pass, since they might get coalesced later on in this pass.
if (lidx < _lrg_map.max_lrg_id() && lrgs(lidx).is_singledef()) {
continue;
}
Block *b_def = _cfg.get_block_for_node(def);
int idx_def = b_def->find_node(def);
// Cannot spill Op_RegFlags.
Node *in_spill;
if (in->ideal_reg() != Op_RegFlags) {
in_spill = get_spillcopy_wide(MachSpillCopyNode::InputToRematerialization, in, def, i);
if (!in_spill) { return 0; } // Bailed out
insert_proj(b_def, idx_def, in_spill, maxlrg++);
if (b_def == b) {
insidx++;
}
def->set_req(i, in_spill);
} else {
// The 'in' defines a flag register. Flag registers can not be spilled.
// Register allocation handles live ranges with flag registers
// by rematerializing the def (in this case 'in'). Thus, this is not
// critical if the input can be rematerialized, too.
if (!in->rematerialize()) {
assert(false, "Can not rematerialize %d: %s. Prolongs RegFlags live"
" range and defining node %d: %s may not be rematerialized.",
def->_idx, def->Name(), in->_idx, in->Name());
C->record_method_not_compilable("attempted to spill a non-spillable item with RegFlags input");
return 0; // Bailed out
}
}
}
}
Node *spill = clone_node(def, b, C);
if (spill == NULL || C->check_node_count(NodeLimitFudgeFactor, out_of_nodes)) {
// Check when generating nodes
return 0;
}
// See if any inputs are currently being spilled, and take the
// latest copy of spilled inputs.
if( spill->req() > 1 ) {
for( uint i = 1; i < spill->req(); i++ ) {
Node *in = spill->in(i);
uint lidx = _lrg_map.find_id(in);
// Walk backwards thru spill copy node intermediates
if (walkThru) {
while (in->is_SpillCopy() && lidx >= _lrg_map.max_lrg_id()) {
in = in->in(1);
lidx = _lrg_map.find_id(in);
}
if (lidx < _lrg_map.max_lrg_id() && lrgs(lidx).is_multidef()) {
// walkThru found a multidef LRG, which is unsafe to use, so
// just keep the original def used in the clone.
in = spill->in(i);
lidx = _lrg_map.find_id(in);
}
}
if (lidx < _lrg_map.max_lrg_id() && lrgs(lidx).reg() >= LRG::SPILL_REG) {
Node *rdef = Reachblock[lrg2reach[lidx]];
if (rdef) {
spill->set_req(i, rdef);
}
}
}
}
assert( spill->out_RegMask().is_UP(), "rematerialize to a reg" );
// Rematerialized op is def->spilled+1
set_was_spilled(spill);
if( _spilled_once.test(def->_idx) )
set_was_spilled(spill);
insert_proj( b, insidx, spill, maxlrg++ );
#ifdef ASSERT
// Increment the counter for this lrg
splits.at_put(slidx, splits.at(slidx)+1);
#endif
// See if the cloned def kills any flags, and copy those kills as well
uint i = insidx+1;
int found_projs = clone_projs( b, i, def, spill, maxlrg);
if (found_projs > 0) {
// Adjust the point where we go hi-pressure
if (i <= b->_ihrp_index) {
b->_ihrp_index += found_projs;
}
if (i <= b->_fhrp_index) {
b->_fhrp_index += found_projs;
}
}
return spill;
}
//------------------------------is_high_pressure-------------------------------
// Function to compute whether or not this live range is "high pressure"
// in this block - whether it spills eagerly or not.
bool PhaseChaitin::is_high_pressure( Block *b, LRG *lrg, uint insidx ) {
if( lrg->_was_spilled1 ) return true;
// Forced spilling due to conflict? Then split only at binding uses
// or defs, not for supposed capacity problems.
// CNC - Turned off 7/8/99, causes too much spilling
// if( lrg->_is_bound ) return false;
// Use float pressure numbers for vectors.
bool is_float_or_vector = lrg->_is_float || lrg->_is_vector;
// Not yet reached the high-pressure cutoff point, so low pressure
uint hrp_idx = is_float_or_vector ? b->_fhrp_index : b->_ihrp_index;
if( insidx < hrp_idx ) return false;
// Register pressure for the block as a whole depends on reg class
int block_pres = is_float_or_vector ? b->_freg_pressure : b->_reg_pressure;
// Bound live ranges will split at the binding points first;
// Intermediate splits should assume the live range's register set
// got "freed up" and that num_regs will become INT_PRESSURE.
int bound_pres = is_float_or_vector ? FLOATPRESSURE : INTPRESSURE;
// Effective register pressure limit.
int lrg_pres = (lrg->get_invalid_mask_size() > lrg->num_regs())
? (lrg->get_invalid_mask_size() >> (lrg->num_regs()-1)) : bound_pres;
// High pressure if block pressure requires more register freedom
// than live range has.
return block_pres >= lrg_pres;
}
//------------------------------prompt_use---------------------------------
// True if lidx is used before any real register is def'd in the block
bool PhaseChaitin::prompt_use( Block *b, uint lidx ) {
if (lrgs(lidx)._was_spilled2) {
return false;
}
// Scan block for 1st use.
for( uint i = 1; i <= b->end_idx(); i++ ) {
Node *n = b->get_node(i);
// Ignore PHI use, these can be up or down
if (n->is_Phi()) {
continue;
}
for (uint j = 1; j < n->req(); j++) {
if (_lrg_map.find_id(n->in(j)) == lidx) {
return true; // Found 1st use!
}
}
if (n->out_RegMask().is_NotEmpty()) {
return false;
}
}
return false;
}
//------------------------------Split--------------------------------------
//----------Split Routine----------
// ***** NEW SPLITTING HEURISTIC *****
// DEFS: If the DEF is in a High Register Pressure(HRP) Block, split there.
// Else, no split unless there is a HRP block between a DEF and
// one of its uses, and then split at the HRP block.
//
// USES: If USE is in HRP, split at use to leave main LRG on stack.
// Else, hoist LRG back up to register only (ie - split is also DEF)
// We will compute a new maxlrg as we go
uint PhaseChaitin::Split(uint maxlrg, ResourceArea* split_arena) {
Compile::TracePhase tp("regAllocSplit", &timers[_t_regAllocSplit]);
// Free thread local resources used by this method on exit.
ResourceMark rm(split_arena);
uint bidx, pidx, slidx, insidx, inpidx, twoidx;
uint non_phi = 1, spill_cnt = 0;
Node *n1, *n2, *n3;
Node_List *defs,*phis;
bool *UPblock;
bool u1, u2, u3;
Block *b, *pred;
PhiNode *phi;
GrowableArray<uint> lidxs(split_arena, maxlrg, 0, 0);
// Array of counters to count splits per live range
GrowableArray<uint> splits(split_arena, maxlrg, 0, 0);
#define NEW_SPLIT_ARRAY(type, size)\
(type*) split_arena->allocate_bytes((size) * sizeof(type))
//----------Setup Code----------
// Create a convenient mapping from lrg numbers to reaches/leaves indices
uint *lrg2reach = NEW_SPLIT_ARRAY(uint, maxlrg);
// Keep track of DEFS & Phis for later passes
defs = new Node_List();
phis = new Node_List();
// Gather info on which LRG's are spilling, and build maps
for (bidx = 1; bidx < maxlrg; bidx++) {
if (lrgs(bidx).alive() && lrgs(bidx).reg() >= LRG::SPILL_REG) {
assert(!lrgs(bidx).mask().is_AllStack(),"AllStack should color");
lrg2reach[bidx] = spill_cnt;
spill_cnt++;
lidxs.append(bidx);
#ifdef ASSERT
// Initialize the split counts to zero
splits.append(0);
#endif
if (PrintOpto && WizardMode && lrgs(bidx)._was_spilled1) {
tty->print_cr("Warning, 2nd spill of L%d",bidx);
}
}
}
// Create side arrays for propagating reaching defs info.
// Each block needs a node pointer for each spilling live range for the
// Def which is live into the block. Phi nodes handle multiple input
// Defs by querying the output of their predecessor blocks and resolving
// them to a single Def at the phi. The pointer is updated for each
// Def in the block, and then becomes the output for the block when
// processing of the block is complete. We also need to track whether
// a Def is UP or DOWN. UP means that it should get a register (ie -
// it is always in LRP regions), and DOWN means that it is probably
// on the stack (ie - it crosses HRP regions).
Node ***Reaches = NEW_SPLIT_ARRAY( Node**, _cfg.number_of_blocks() + 1);
bool **UP = NEW_SPLIT_ARRAY( bool*, _cfg.number_of_blocks() + 1);
Node **debug_defs = NEW_SPLIT_ARRAY( Node*, spill_cnt );
VectorSet **UP_entry= NEW_SPLIT_ARRAY( VectorSet*, spill_cnt );
// Initialize Reaches & UP
for (bidx = 0; bidx < _cfg.number_of_blocks() + 1; bidx++) {
Reaches[bidx] = NEW_SPLIT_ARRAY( Node*, spill_cnt );
UP[bidx] = NEW_SPLIT_ARRAY( bool, spill_cnt );
Node **Reachblock = Reaches[bidx];
bool *UPblock = UP[bidx];
for( slidx = 0; slidx < spill_cnt; slidx++ ) {
UPblock[slidx] = true; // Assume they start in registers
Reachblock[slidx] = NULL; // Assume that no def is present
}
}
#undef NEW_SPLIT_ARRAY
// Initialize to array of empty vectorsets
for( slidx = 0; slidx < spill_cnt; slidx++ )
UP_entry[slidx] = new VectorSet(split_arena);
//----------PASS 1----------
//----------Propagation & Node Insertion Code----------
// Walk the Blocks in RPO for DEF & USE info
for( bidx = 0; bidx < _cfg.number_of_blocks(); bidx++ ) {
if (C->check_node_count(spill_cnt, out_of_nodes)) {
return 0;
}
b = _cfg.get_block(bidx);
// Reaches & UP arrays for this block
Node** Reachblock = Reaches[b->_pre_order];
UPblock = UP[b->_pre_order];
// Reset counter of start of non-Phi nodes in block
non_phi = 1;
//----------Block Entry Handling----------
// Check for need to insert a new phi
// Cycle through this block's predecessors, collecting Reaches
// info for each spilled LRG. If they are identical, no phi is
// needed. If they differ, check for a phi, and insert if missing,
// or update edges if present. Set current block's Reaches set to
// be either the phi's or the reaching def, as appropriate.
// If no Phi is needed, check if the LRG needs to spill on entry
// to the block due to HRP.
for( slidx = 0; slidx < spill_cnt; slidx++ ) {
// Grab the live range number
uint lidx = lidxs.at(slidx);
// Do not bother splitting or putting in Phis for single-def
// rematerialized live ranges. This happens alot to constants
// with long live ranges.
if( lrgs(lidx).is_singledef() &&
lrgs(lidx)._def->rematerialize() ) {
// reset the Reaches & UP entries
Reachblock[slidx] = lrgs(lidx)._def;
UPblock[slidx] = true;
// Record following instruction in case 'n' rematerializes and
// kills flags
Block *pred1 = _cfg.get_block_for_node(b->pred(1));
continue;
}
// Initialize needs_phi and needs_split
bool needs_phi = false;
bool needs_split = false;
bool has_phi = false;
// Walk the predecessor blocks to check inputs for that live range
// Grab predecessor block header
n1 = b->pred(1);
// Grab the appropriate reaching def info for inpidx
pred = _cfg.get_block_for_node(n1);
pidx = pred->_pre_order;
Node **Ltmp = Reaches[pidx];
bool *Utmp = UP[pidx];
n1 = Ltmp[slidx];
u1 = Utmp[slidx];
// Initialize node for saving type info
n3 = n1;
u3 = u1;
// Compare inputs to see if a Phi is needed
for( inpidx = 2; inpidx < b->num_preds(); inpidx++ ) {
// Grab predecessor block headers
n2 = b->pred(inpidx);
// Grab the appropriate reaching def info for inpidx
pred = _cfg.get_block_for_node(n2);
pidx = pred->_pre_order;
Ltmp = Reaches[pidx];
Utmp = UP[pidx];
n2 = Ltmp[slidx];
u2 = Utmp[slidx];
// For each LRG, decide if a phi is necessary
if( n1 != n2 ) {
needs_phi = true;
}
// See if the phi has mismatched inputs, UP vs. DOWN
if( n1 && n2 && (u1 != u2) ) {
needs_split = true;
}
// Move n2/u2 to n1/u1 for next iteration
n1 = n2;
u1 = u2;
// Preserve a non-NULL predecessor for later type referencing
if( (n3 == NULL) && (n2 != NULL) ){
n3 = n2;
u3 = u2;
}
} // End for all potential Phi inputs
// check block for appropriate phinode & update edges
for( insidx = 1; insidx <= b->end_idx(); insidx++ ) {
n1 = b->get_node(insidx);
// bail if this is not a phi
phi = n1->is_Phi() ? n1->as_Phi() : NULL;
if( phi == NULL ) {
// Keep track of index of first non-PhiNode instruction in block
non_phi = insidx;
// break out of the for loop as we have handled all phi nodes
break;
}
// must be looking at a phi
if (_lrg_map.find_id(n1) == lidxs.at(slidx)) {
// found the necessary phi
needs_phi = false;
has_phi = true;
// initialize the Reaches entry for this LRG
Reachblock[slidx] = phi;
break;
} // end if found correct phi
} // end for all phi's
// If a phi is needed or exist, check for it
if( needs_phi || has_phi ) {
// add new phinode if one not already found
if( needs_phi ) {
// create a new phi node and insert it into the block
// type is taken from left over pointer to a predecessor
guarantee(n3, "No non-NULL reaching DEF for a Phi");
phi = new PhiNode(b->head(), n3->bottom_type());
// initialize the Reaches entry for this LRG
Reachblock[slidx] = phi;
// add node to block & node_to_block mapping
insert_proj(b, insidx++, phi, maxlrg++);
non_phi++;
// Reset new phi's mapping to be the spilling live range
_lrg_map.map(phi->_idx, lidx);
assert(_lrg_map.find_id(phi) == lidx, "Bad update on Union-Find mapping");
} // end if not found correct phi
// Here you have either found or created the Phi, so record it
assert(phi != NULL,"Must have a Phi Node here");
phis->push(phi);
// PhiNodes should either force the LRG UP or DOWN depending
// on its inputs and the register pressure in the Phi's block.
UPblock[slidx] = true; // Assume new DEF is UP
// If entering a high-pressure area with no immediate use,
// assume Phi is DOWN
if( is_high_pressure( b, &lrgs(lidx), b->end_idx()) && !prompt_use(b,lidx) )
UPblock[slidx] = false;
// If we are not split up/down and all inputs are down, then we
// are down
if( !needs_split && !u3 )
UPblock[slidx] = false;
} // end if phi is needed
// Do not need a phi, so grab the reaching DEF
else {
// Grab predecessor block header
n1 = b->pred(1);
// Grab the appropriate reaching def info for k
pred = _cfg.get_block_for_node(n1);
pidx = pred->_pre_order;
Node **Ltmp = Reaches[pidx];
bool *Utmp = UP[pidx];
// reset the Reaches & UP entries
Reachblock[slidx] = Ltmp[slidx];
UPblock[slidx] = Utmp[slidx];
} // end else no Phi is needed
} // end for all spilling live ranges
// DEBUG
#ifndef PRODUCT
if(trace_spilling()) {
tty->print("/`\nBlock %d: ", b->_pre_order);
tty->print("Reaching Definitions after Phi handling\n");
for( uint x = 0; x < spill_cnt; x++ ) {
tty->print("Spill Idx %d: UP %d: Node\n",x,UPblock[x]);
if( Reachblock[x] )
Reachblock[x]->dump();
else
tty->print("Undefined\n");
}
}
#endif
//----------Non-Phi Node Splitting----------
// Since phi-nodes have now been handled, the Reachblock array for this
// block is initialized with the correct starting value for the defs which
// reach non-phi instructions in this block. Thus, process non-phi
// instructions normally, inserting SpillCopy nodes for all spill
// locations.
// Memoize any DOWN reaching definitions for use as DEBUG info
for( insidx = 0; insidx < spill_cnt; insidx++ ) {
debug_defs[insidx] = (UPblock[insidx]) ? NULL : Reachblock[insidx];
if( UPblock[insidx] ) // Memoize UP decision at block start
UP_entry[insidx]->set( b->_pre_order );
}
//----------Walk Instructions in the Block and Split----------
// For all non-phi instructions in the block
for( insidx = 1; insidx <= b->end_idx(); insidx++ ) {
Node *n = b->get_node(insidx);
// Find the defining Node's live range index
uint defidx = _lrg_map.find_id(n);
uint cnt = n->req();
if (n->is_Phi()) {
// Skip phi nodes after removing dead copies.
if (defidx < _lrg_map.max_lrg_id()) {
// Check for useless Phis. These appear if we spill, then
// coalesce away copies. Dont touch Phis in spilling live
// ranges; they are busy getting modifed in this pass.
if( lrgs(defidx).reg() < LRG::SPILL_REG ) {
uint i;
Node *u = NULL;
// Look for the Phi merging 2 unique inputs
for( i = 1; i < cnt; i++ ) {
// Ignore repeats and self
if( n->in(i) != u && n->in(i) != n ) {
// Found a unique input
if( u != NULL ) // If it's the 2nd, bail out
break;
u = n->in(i); // Else record it
}
}
assert( u, "at least 1 valid input expected" );
if (i >= cnt) { // Found one unique input
assert(_lrg_map.find_id(n) == _lrg_map.find_id(u), "should be the same lrg");
n->replace_by(u); // Then replace with unique input
n->disconnect_inputs(NULL, C);
b->remove_node(insidx);
insidx--;
b->_ihrp_index--;
b->_fhrp_index--;
}
}
}
continue;
}
assert( insidx > b->_ihrp_index ||
(b->_reg_pressure < (uint)INTPRESSURE) ||
b->_ihrp_index > 4000000 ||
b->_ihrp_index >= b->end_idx() ||
!b->get_node(b->_ihrp_index)->is_Proj(), "" );
assert( insidx > b->_fhrp_index ||
(b->_freg_pressure < (uint)FLOATPRESSURE) ||
b->_fhrp_index > 4000000 ||
b->_fhrp_index >= b->end_idx() ||
!b->get_node(b->_fhrp_index)->is_Proj(), "" );
// ********** Handle Crossing HRP Boundry **********
if( (insidx == b->_ihrp_index) || (insidx == b->_fhrp_index) ) {
for( slidx = 0; slidx < spill_cnt; slidx++ ) {
// Check for need to split at HRP boundary - split if UP
n1 = Reachblock[slidx];
// bail out if no reaching DEF
if( n1 == NULL ) continue;
// bail out if live range is 'isolated' around inner loop
uint lidx = lidxs.at(slidx);
// If live range is currently UP
if( UPblock[slidx] ) {
// set location to insert spills at
// SPLIT DOWN HERE - NO CISC SPILL
if( is_high_pressure( b, &lrgs(lidx), insidx ) &&
!n1->rematerialize() ) {
// If there is already a valid stack definition available, use it
if( debug_defs[slidx] != NULL ) {
Reachblock[slidx] = debug_defs[slidx];
}
else {
// Insert point is just past last use or def in the block
int insert_point = insidx-1;
while( insert_point > 0 ) {
Node *n = b->get_node(insert_point);
// Hit top of block? Quit going backwards
if (n->is_Phi()) {
break;
}
// Found a def? Better split after it.
if (_lrg_map.live_range_id(n) == lidx) {
break;
}
// Look for a use
uint i;
for( i = 1; i < n->req(); i++ ) {
if (_lrg_map.live_range_id(n->in(i)) == lidx) {
break;
}
}
// Found a use? Better split after it.
if (i < n->req()) {
break;
}
insert_point--;
}
uint orig_eidx = b->end_idx();
maxlrg = split_DEF( n1, b, insert_point, maxlrg, Reachblock, debug_defs, splits, slidx);
// If it wasn't split bail
if (!maxlrg) {
return 0;
}
// Spill of NULL check mem op goes into the following block.
if (b->end_idx() > orig_eidx) {
insidx++;
}
}
// This is a new DEF, so update UP
UPblock[slidx] = false;
#ifndef PRODUCT
// DEBUG
if( trace_spilling() ) {
tty->print("\nNew Split DOWN DEF of Spill Idx ");
tty->print("%d, UP %d:\n",slidx,false);
n1->dump();
}
#endif
}
} // end if LRG is UP
} // end for all spilling live ranges
assert( b->get_node(insidx) == n, "got insidx set incorrectly" );
} // end if crossing HRP Boundry
// If the LRG index is oob, then this is a new spillcopy, skip it.
if (defidx >= _lrg_map.max_lrg_id()) {
continue;
}
LRG &deflrg = lrgs(defidx);
uint copyidx = n->is_Copy();
// Remove coalesced copy from CFG
if (copyidx && defidx == _lrg_map.live_range_id(n->in(copyidx))) {
n->replace_by( n->in(copyidx) );
n->set_req( copyidx, NULL );
b->remove_node(insidx--);
b->_ihrp_index--; // Adjust the point where we go hi-pressure
b->_fhrp_index--;
continue;
}
#define DERIVED 0
// ********** Handle USES **********
bool nullcheck = false;
// Implicit null checks never use the spilled value
if( n->is_MachNullCheck() )
nullcheck = true;
if( !nullcheck ) {
// Search all inputs for a Spill-USE
JVMState* jvms = n->jvms();
uint oopoff = jvms ? jvms->oopoff() : cnt;
uint old_last = cnt - 1;
for( inpidx = 1; inpidx < cnt; inpidx++ ) {
// Derived/base pairs may be added to our inputs during this loop.
// If inpidx > old_last, then one of these new inputs is being
// handled. Skip the derived part of the pair, but process
// the base like any other input.
if (inpidx > old_last && ((inpidx - oopoff) & 1) == DERIVED) {
continue; // skip derived_debug added below
}
// Get lidx of input
uint useidx = _lrg_map.find_id(n->in(inpidx));
// Not a brand-new split, and it is a spill use
if (useidx < _lrg_map.max_lrg_id() && lrgs(useidx).reg() >= LRG::SPILL_REG) {
// Check for valid reaching DEF
slidx = lrg2reach[useidx];
Node *def = Reachblock[slidx];
assert( def != NULL, "Using Undefined Value in Split()\n");
// (+++) %%%% remove this in favor of pre-pass in matcher.cpp
// monitor references do not care where they live, so just hook
if ( jvms && jvms->is_monitor_use(inpidx) ) {
// The effect of this clone is to drop the node out of the block,
// so that the allocator does not see it anymore, and therefore
// does not attempt to assign it a register.
def = clone_node(def, b, C);
if (def == NULL || C->check_node_count(NodeLimitFudgeFactor, out_of_nodes)) {
return 0;
}
_lrg_map.extend(def->_idx, 0);
_cfg.map_node_to_block(def, b);
n->set_req(inpidx, def);
continue;
}
// Rematerializable? Then clone def at use site instead
// of store/load
if( def->rematerialize() ) {
int old_size = b->number_of_nodes();
def = split_Rematerialize( def, b, insidx, maxlrg, splits, slidx, lrg2reach, Reachblock, true );
if( !def ) return 0; // Bail out
insidx += b->number_of_nodes()-old_size;
}
MachNode *mach = n->is_Mach() ? n->as_Mach() : NULL;
// Base pointers and oopmap references do not care where they live.
if ((inpidx >= oopoff) ||
(mach && mach->ideal_Opcode() == Op_AddP && inpidx == AddPNode::Base)) {
if (def->rematerialize() && lrgs(useidx)._was_spilled2) {
// This def has been rematerialized a couple of times without
// progress. It doesn't care if it lives UP or DOWN, so
// spill it down now.
maxlrg = split_USE(MachSpillCopyNode::BasePointerToMem, def,b,n,inpidx,maxlrg,false,false,splits,slidx);
// If it wasn't split bail
if (!maxlrg) {
return 0;
}
insidx++; // Reset iterator to skip USE side split
} else {
// Just hook the def edge
n->set_req(inpidx, def);
}
if (inpidx >= oopoff) {
// After oopoff, we have derived/base pairs. We must mention all
// derived pointers here as derived/base pairs for GC. If the
// derived value is spilling and we have a copy both in Reachblock
// (called here 'def') and debug_defs[slidx] we need to mention
// both in derived/base pairs or kill one.
Node *derived_debug = debug_defs[slidx];
if( ((inpidx - oopoff) & 1) == DERIVED && // derived vs base?
mach && mach->ideal_Opcode() != Op_Halt &&
derived_debug != NULL &&
derived_debug != def ) { // Actual 2nd value appears
// We have already set 'def' as a derived value.
// Also set debug_defs[slidx] as a derived value.
uint k;
for( k = oopoff; k < cnt; k += 2 )
if( n->in(k) == derived_debug )
break; // Found an instance of debug derived
if( k == cnt ) {// No instance of debug_defs[slidx]
// Add a derived/base pair to cover the debug info.
// We have to process the added base later since it is not
// handled yet at this point but skip derived part.
assert(((n->req() - oopoff) & 1) == DERIVED,
"must match skip condition above");
n->add_req( derived_debug ); // this will be skipped above
n->add_req( n->in(inpidx+1) ); // this will be processed
// Increment cnt to handle added input edges on
// subsequent iterations.
cnt += 2;
}
}
}
continue;
}
// Special logic for DEBUG info
if( jvms && b->_freq > BLOCK_FREQUENCY(0.5) ) {
uint debug_start = jvms->debug_start();
// If this is debug info use & there is a reaching DOWN def
if ((debug_start <= inpidx) && (debug_defs[slidx] != NULL)) {
assert(inpidx < oopoff, "handle only debug info here");
// Just hook it in & move on
n->set_req(inpidx, debug_defs[slidx]);
// (Note that this can make two sides of a split live at the
// same time: The debug def on stack, and another def in a
// register. The GC needs to know about both of them, but any
// derived pointers after oopoff will refer to only one of the
// two defs and the GC would therefore miss the other. Thus
// this hack is only allowed for debug info which is Java state
// and therefore never a derived pointer.)
continue;
}
}
// Grab register mask info
const RegMask &dmask = def->out_RegMask();
const RegMask &umask = n->in_RegMask(inpidx);
bool is_vect = RegMask::is_vector(def->ideal_reg());
assert(inpidx < oopoff, "cannot use-split oop map info");
bool dup = UPblock[slidx];
bool uup = umask.is_UP();
// Need special logic to handle bound USES. Insert a split at this
// bound use if we can't rematerialize the def, or if we need the
// split to form a misaligned pair.
if( !umask.is_AllStack() &&
(int)umask.Size() <= lrgs(useidx).num_regs() &&
(!def->rematerialize() ||
(!is_vect && umask.is_misaligned_pair()))) {
// These need a Split regardless of overlap or pressure
// SPLIT - NO DEF - NO CISC SPILL
maxlrg = split_USE(MachSpillCopyNode::Bound, def,b,n,inpidx,maxlrg,dup,false, splits,slidx);
// If it wasn't split bail
if (!maxlrg) {
return 0;
}
insidx++; // Reset iterator to skip USE side split
continue;
}
if (UseFPUForSpilling && n->is_MachCall() && !uup && !dup ) {
// The use at the call can force the def down so insert
// a split before the use to allow the def more freedom.
maxlrg = split_USE(MachSpillCopyNode::CallUse, def,b,n,inpidx,maxlrg,dup,false, splits,slidx);
// If it wasn't split bail
if (!maxlrg) {
return 0;
}
insidx++; // Reset iterator to skip USE side split
continue;
}
// Here is the logic chart which describes USE Splitting:
// 0 = false or DOWN, 1 = true or UP
//
// Overlap | DEF | USE | Action
//-------------------------------------------------------
// 0 | 0 | 0 | Copy - mem -> mem
// 0 | 0 | 1 | Split-UP - Check HRP
// 0 | 1 | 0 | Split-DOWN - Debug Info?
// 0 | 1 | 1 | Copy - reg -> reg
// 1 | 0 | 0 | Reset Input Edge (no Split)
// 1 | 0 | 1 | Split-UP - Check HRP
// 1 | 1 | 0 | Split-DOWN - Debug Info?
// 1 | 1 | 1 | Reset Input Edge (no Split)
//
// So, if (dup == uup), then overlap test determines action,
// with true being no split, and false being copy. Else,
// if DEF is DOWN, Split-UP, and check HRP to decide on
// resetting DEF. Finally if DEF is UP, Split-DOWN, with
// special handling for Debug Info.
if( dup == uup ) {
if( dmask.overlap(umask) ) {
// Both are either up or down, and there is overlap, No Split
n->set_req(inpidx, def);
}
else { // Both are either up or down, and there is no overlap
if( dup ) { // If UP, reg->reg copy
// COPY ACROSS HERE - NO DEF - NO CISC SPILL
maxlrg = split_USE(MachSpillCopyNode::RegToReg, def,b,n,inpidx,maxlrg,false,false, splits,slidx);
// If it wasn't split bail
if (!maxlrg) {
return 0;
}
insidx++; // Reset iterator to skip USE side split
}
else { // DOWN, mem->mem copy
// COPY UP & DOWN HERE - NO DEF - NO CISC SPILL
// First Split-UP to move value into Register
uint def_ideal = def->ideal_reg();
const RegMask* tmp_rm = Matcher::idealreg2regmask[def_ideal];
Node *spill = new MachSpillCopyNode(MachSpillCopyNode::MemToReg, def, dmask, *tmp_rm);
insert_proj( b, insidx, spill, maxlrg );
// Then Split-DOWN as if previous Split was DEF
maxlrg = split_USE(MachSpillCopyNode::RegToMem, spill,b,n,inpidx,maxlrg,false,false, splits,slidx);
// If it wasn't split bail
if (!maxlrg) {
return 0;
}
insidx += 2; // Reset iterator to skip USE side splits
}
} // End else no overlap
} // End if dup == uup
// dup != uup, so check dup for direction of Split
else {
if( dup ) { // If UP, Split-DOWN and check Debug Info
// If this node is already a SpillCopy, just patch the edge
// except the case of spilling to stack.
if( n->is_SpillCopy() ) {
RegMask tmp_rm(umask);
tmp_rm.SUBTRACT(Matcher::STACK_ONLY_mask);
if( dmask.overlap(tmp_rm) ) {
if( def != n->in(inpidx) ) {
n->set_req(inpidx, def);
}
continue;
}
}
// COPY DOWN HERE - NO DEF - NO CISC SPILL
maxlrg = split_USE(MachSpillCopyNode::RegToMem, def,b,n,inpidx,maxlrg,false,false, splits,slidx);
// If it wasn't split bail
if (!maxlrg) {
return 0;
}
insidx++; // Reset iterator to skip USE side split
// Check for debug-info split. Capture it for later
// debug splits of the same value
if (jvms && jvms->debug_start() <= inpidx && inpidx < oopoff)
debug_defs[slidx] = n->in(inpidx);
}
else { // DOWN, Split-UP and check register pressure
if( is_high_pressure( b, &lrgs(useidx), insidx ) ) {
// COPY UP HERE - NO DEF - CISC SPILL
maxlrg = split_USE(MachSpillCopyNode::MemToReg, def,b,n,inpidx,maxlrg,true,true, splits,slidx);
// If it wasn't split bail
if (!maxlrg) {
return 0;
}
insidx++; // Reset iterator to skip USE side split
} else { // LRP
// COPY UP HERE - WITH DEF - NO CISC SPILL
maxlrg = split_USE(MachSpillCopyNode::MemToReg, def,b,n,inpidx,maxlrg,true,false, splits,slidx);
// If it wasn't split bail
if (!maxlrg) {
return 0;
}
// Flag this lift-up in a low-pressure block as
// already-spilled, so if it spills again it will
// spill hard (instead of not spilling hard and
// coalescing away).
set_was_spilled(n->in(inpidx));
// Since this is a new DEF, update Reachblock & UP
Reachblock[slidx] = n->in(inpidx);
UPblock[slidx] = true;
insidx++; // Reset iterator to skip USE side split
}
} // End else DOWN
} // End dup != uup
} // End if Spill USE
} // End For All Inputs
} // End If not nullcheck
// ********** Handle DEFS **********
// DEFS either Split DOWN in HRP regions or when the LRG is bound, or
// just reset the Reaches info in LRP regions. DEFS must always update
// UP info.
if( deflrg.reg() >= LRG::SPILL_REG ) { // Spilled?
uint slidx = lrg2reach[defidx];
// Add to defs list for later assignment of new live range number
defs->push(n);
// Set a flag on the Node indicating it has already spilled.
// Only do it for capacity spills not conflict spills.
if( !deflrg._direct_conflict )
set_was_spilled(n);
assert(!n->is_Phi(),"Cannot insert Phi into DEFS list");
// Grab UP info for DEF
const RegMask &dmask = n->out_RegMask();
bool defup = dmask.is_UP();
uint ireg = n->ideal_reg();
bool is_vect = RegMask::is_vector(ireg);
// Only split at Def if this is a HRP block or bound (and spilled once)
if( !n->rematerialize() &&
(((dmask.is_bound(ireg) || (!is_vect && dmask.is_misaligned_pair())) &&
(deflrg._direct_conflict || deflrg._must_spill)) ||
// Check for LRG being up in a register and we are inside a high
// pressure area. Spill it down immediately.
(defup && is_high_pressure(b,&deflrg,insidx) && !n->is_SpillCopy())) ) {
assert( !n->rematerialize(), "" );
// Do a split at the def site.
maxlrg = split_DEF( n, b, insidx, maxlrg, Reachblock, debug_defs, splits, slidx );
// If it wasn't split bail
if (!maxlrg) {
return 0;
}
// Split DEF's Down
UPblock[slidx] = 0;
#ifndef PRODUCT
// DEBUG
if( trace_spilling() ) {
tty->print("\nNew Split DOWN DEF of Spill Idx ");
tty->print("%d, UP %d:\n",slidx,false);
n->dump();
}
#endif
}
else { // Neither bound nor HRP, must be LRP
// otherwise, just record the def
Reachblock[slidx] = n;
// UP should come from the outRegmask() of the DEF
UPblock[slidx] = defup;
// Update debug list of reaching down definitions, kill if DEF is UP
debug_defs[slidx] = defup ? NULL : n;
#ifndef PRODUCT
// DEBUG
if( trace_spilling() ) {
tty->print("\nNew DEF of Spill Idx ");
tty->print("%d, UP %d:\n",slidx,defup);
n->dump();
}
#endif
} // End else LRP
} // End if spill def
// ********** Split Left Over Mem-Mem Moves **********
// Check for mem-mem copies and split them now. Do not do this
// to copies about to be spilled; they will be Split shortly.
if (copyidx) {
Node *use = n->in(copyidx);
uint useidx = _lrg_map.find_id(use);
if (useidx < _lrg_map.max_lrg_id() && // This is not a new split
OptoReg::is_stack(deflrg.reg()) &&
deflrg.reg() < LRG::SPILL_REG ) { // And DEF is from stack
LRG &uselrg = lrgs(useidx);
if( OptoReg::is_stack(uselrg.reg()) &&
uselrg.reg() < LRG::SPILL_REG && // USE is from stack
deflrg.reg() != uselrg.reg() ) { // Not trivially removed
uint def_ideal_reg = n->bottom_type()->ideal_reg();
const RegMask &def_rm = *Matcher::idealreg2regmask[def_ideal_reg];
const RegMask &use_rm = n->in_RegMask(copyidx);
if( def_rm.overlap(use_rm) && n->is_SpillCopy() ) { // Bug 4707800, 'n' may be a storeSSL
if (C->check_node_count(NodeLimitFudgeFactor, out_of_nodes)) { // Check when generating nodes
return 0;
}
Node *spill = new MachSpillCopyNode(MachSpillCopyNode::MemToReg, use,use_rm,def_rm);
n->set_req(copyidx,spill);
n->as_MachSpillCopy()->set_in_RegMask(def_rm);
// Put the spill just before the copy
insert_proj( b, insidx++, spill, maxlrg++ );
}
}
}
}
} // End For All Instructions in Block - Non-PHI Pass
// Check if each LRG is live out of this block so as not to propagate
// beyond the last use of a LRG.
for( slidx = 0; slidx < spill_cnt; slidx++ ) {
uint defidx = lidxs.at(slidx);
IndexSet *liveout = _live->live(b);
if( !liveout->member(defidx) ) {
#ifdef ASSERT
// The index defidx is not live. Check the liveout array to ensure that
// it contains no members which compress to defidx. Finding such an
// instance may be a case to add liveout adjustment in compress_uf_map().
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