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llvm-6502/lib/CodeGen/RegAlloc/PhyRegAlloc.cpp
Brian Gaeke bd353fb662 Use C++ math header instead of C version. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8648 91177308-0d34-0410-b5e6-96231b3b80d8
2003-09-21 03:57:37 +00:00

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//===-- PhyRegAlloc.cpp ---------------------------------------------------===//
//
// Register allocation for LLVM.
//
//===----------------------------------------------------------------------===//
#include "PhyRegAlloc.h"
#include "RegAllocCommon.h"
#include "RegClass.h"
#include "IGNode.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineInstrAnnot.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionInfo.h"
#include "llvm/CodeGen/FunctionLiveVarInfo.h"
#include "llvm/CodeGen/InstrSelection.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Function.h"
#include "llvm/Type.h"
#include "llvm/iOther.h"
#include "Support/STLExtras.h"
#include "Support/SetOperations.h"
#include "Support/CommandLine.h"
#include <cmath>
RegAllocDebugLevel_t DEBUG_RA;
static cl::opt<RegAllocDebugLevel_t, true>
DRA_opt("dregalloc", cl::Hidden, cl::location(DEBUG_RA),
cl::desc("enable register allocation debugging information"),
cl::values(
clEnumValN(RA_DEBUG_None , "n", "disable debug output"),
clEnumValN(RA_DEBUG_Results, "y", "debug output for allocation results"),
clEnumValN(RA_DEBUG_Coloring, "c", "debug output for graph coloring step"),
clEnumValN(RA_DEBUG_Interference,"ig","debug output for interference graphs"),
clEnumValN(RA_DEBUG_LiveRanges , "lr","debug output for live ranges"),
clEnumValN(RA_DEBUG_Verbose, "v", "extra debug output"),
0));
FunctionPass *getRegisterAllocator(TargetMachine &T) {
return new PhyRegAlloc (T);
}
//----------------------------------------------------------------------------
// This method initially creates interference graphs (one in each reg class)
// and IGNodeList (one in each IG). The actual nodes will be pushed later.
//----------------------------------------------------------------------------
void PhyRegAlloc::createIGNodeListsAndIGs() {
if (DEBUG_RA >= RA_DEBUG_LiveRanges) std::cerr << "Creating LR lists ...\n";
// hash map iterator
LiveRangeMapType::const_iterator HMI = LRI->getLiveRangeMap()->begin();
// hash map end
LiveRangeMapType::const_iterator HMIEnd = LRI->getLiveRangeMap()->end();
for (; HMI != HMIEnd ; ++HMI ) {
if (HMI->first) {
LiveRange *L = HMI->second; // get the LiveRange
if (!L) {
if (DEBUG_RA)
std::cerr << "\n**** ?!?WARNING: NULL LIVE RANGE FOUND FOR: "
<< RAV(HMI->first) << "****\n";
continue;
}
// if the Value * is not null, and LR is not yet written to the IGNodeList
if (!(L->getUserIGNode()) ) {
RegClass *const RC = // RegClass of first value in the LR
RegClassList[ L->getRegClass()->getID() ];
RC->addLRToIG(L); // add this LR to an IG
}
}
}
// init RegClassList
for ( unsigned rc=0; rc < NumOfRegClasses ; rc++)
RegClassList[rc]->createInterferenceGraph();
if (DEBUG_RA >= RA_DEBUG_LiveRanges) std::cerr << "LRLists Created!\n";
}
//----------------------------------------------------------------------------
// This method will add all interferences at for a given instruction.
// Interference occurs only if the LR of Def (Inst or Arg) is of the same reg
// class as that of live var. The live var passed to this function is the
// LVset AFTER the instruction
//----------------------------------------------------------------------------
void PhyRegAlloc::addInterference(const Value *Def,
const ValueSet *LVSet,
bool isCallInst) {
ValueSet::const_iterator LIt = LVSet->begin();
// get the live range of instruction
const LiveRange *const LROfDef = LRI->getLiveRangeForValue( Def );
IGNode *const IGNodeOfDef = LROfDef->getUserIGNode();
assert( IGNodeOfDef );
RegClass *const RCOfDef = LROfDef->getRegClass();
// for each live var in live variable set
for ( ; LIt != LVSet->end(); ++LIt) {
if (DEBUG_RA >= RA_DEBUG_Verbose)
std::cerr << "< Def=" << RAV(Def) << ", Lvar=" << RAV(*LIt) << "> ";
// get the live range corresponding to live var
LiveRange *LROfVar = LRI->getLiveRangeForValue(*LIt);
// LROfVar can be null if it is a const since a const
// doesn't have a dominating def - see Assumptions above
if (LROfVar)
if (LROfDef != LROfVar) // do not set interf for same LR
if (RCOfDef == LROfVar->getRegClass()) // 2 reg classes are the same
RCOfDef->setInterference( LROfDef, LROfVar);
}
}
//----------------------------------------------------------------------------
// For a call instruction, this method sets the CallInterference flag in
// the LR of each variable live int the Live Variable Set live after the
// call instruction (except the return value of the call instruction - since
// the return value does not interfere with that call itself).
//----------------------------------------------------------------------------
void PhyRegAlloc::setCallInterferences(const MachineInstr *MInst,
const ValueSet *LVSetAft) {
if (DEBUG_RA >= RA_DEBUG_Interference)
std::cerr << "\n For call inst: " << *MInst;
// for each live var in live variable set after machine inst
for (ValueSet::const_iterator LIt = LVSetAft->begin(), LEnd = LVSetAft->end();
LIt != LEnd; ++LIt) {
// get the live range corresponding to live var
LiveRange *const LR = LRI->getLiveRangeForValue(*LIt );
// LR can be null if it is a const since a const
// doesn't have a dominating def - see Assumptions above
if (LR ) {
if (DEBUG_RA >= RA_DEBUG_Interference) {
std::cerr << "\n\tLR after Call: ";
printSet(*LR);
}
LR->setCallInterference();
if (DEBUG_RA >= RA_DEBUG_Interference) {
std::cerr << "\n ++After adding call interference for LR: " ;
printSet(*LR);
}
}
}
// Now find the LR of the return value of the call
// We do this because, we look at the LV set *after* the instruction
// to determine, which LRs must be saved across calls. The return value
// of the call is live in this set - but it does not interfere with call
// (i.e., we can allocate a volatile register to the return value)
CallArgsDescriptor* argDesc = CallArgsDescriptor::get(MInst);
if (const Value *RetVal = argDesc->getReturnValue()) {
LiveRange *RetValLR = LRI->getLiveRangeForValue( RetVal );
assert( RetValLR && "No LR for RetValue of call");
RetValLR->clearCallInterference();
}
// If the CALL is an indirect call, find the LR of the function pointer.
// That has a call interference because it conflicts with outgoing args.
if (const Value *AddrVal = argDesc->getIndirectFuncPtr()) {
LiveRange *AddrValLR = LRI->getLiveRangeForValue( AddrVal );
assert( AddrValLR && "No LR for indirect addr val of call");
AddrValLR->setCallInterference();
}
}
//----------------------------------------------------------------------------
// This method will walk thru code and create interferences in the IG of
// each RegClass. Also, this method calculates the spill cost of each
// Live Range (it is done in this method to save another pass over the code).
//----------------------------------------------------------------------------
void PhyRegAlloc::buildInterferenceGraphs()
{
if (DEBUG_RA >= RA_DEBUG_Interference)
std::cerr << "Creating interference graphs ...\n";
unsigned BBLoopDepthCost;
for (MachineFunction::iterator BBI = MF->begin(), BBE = MF->end();
BBI != BBE; ++BBI) {
const MachineBasicBlock &MBB = *BBI;
const BasicBlock *BB = MBB.getBasicBlock();
// find the 10^(loop_depth) of this BB
BBLoopDepthCost = (unsigned)pow(10.0, LoopDepthCalc->getLoopDepth(BB));
// get the iterator for machine instructions
MachineBasicBlock::const_iterator MII = MBB.begin();
// iterate over all the machine instructions in BB
for ( ; MII != MBB.end(); ++MII) {
const MachineInstr *MInst = *MII;
// get the LV set after the instruction
const ValueSet &LVSetAI = LVI->getLiveVarSetAfterMInst(MInst, BB);
bool isCallInst = TM.getInstrInfo().isCall(MInst->getOpCode());
if (isCallInst ) {
// set the isCallInterference flag of each live range which extends
// across this call instruction. This information is used by graph
// coloring algorithm to avoid allocating volatile colors to live ranges
// that span across calls (since they have to be saved/restored)
setCallInterferences(MInst, &LVSetAI);
}
// iterate over all MI operands to find defs
for (MachineInstr::const_val_op_iterator OpI = MInst->begin(),
OpE = MInst->end(); OpI != OpE; ++OpI) {
if (OpI.isDefOnly() || OpI.isDefAndUse()) // create a new LR since def
addInterference(*OpI, &LVSetAI, isCallInst);
// Calculate the spill cost of each live range
LiveRange *LR = LRI->getLiveRangeForValue(*OpI);
if (LR) LR->addSpillCost(BBLoopDepthCost);
}
// if there are multiple defs in this instruction e.g. in SETX
if (TM.getInstrInfo().isPseudoInstr(MInst->getOpCode()))
addInterf4PseudoInstr(MInst);
// Also add interference for any implicit definitions in a machine
// instr (currently, only calls have this).
unsigned NumOfImpRefs = MInst->getNumImplicitRefs();
for (unsigned z=0; z < NumOfImpRefs; z++)
if (MInst->getImplicitOp(z).opIsDefOnly() ||
MInst->getImplicitOp(z).opIsDefAndUse())
addInterference( MInst->getImplicitRef(z), &LVSetAI, isCallInst );
} // for all machine instructions in BB
} // for all BBs in function
// add interferences for function arguments. Since there are no explicit
// defs in the function for args, we have to add them manually
addInterferencesForArgs();
if (DEBUG_RA >= RA_DEBUG_Interference)
std::cerr << "Interference graphs calculated!\n";
}
//--------------------------------------------------------------------------
// Pseudo-instructions may be expanded to multiple instructions by the
// assembler. Consequently, all the operands must get distinct registers.
// Therefore, we mark all operands of a pseudo-instruction as interfering
// with one another.
//--------------------------------------------------------------------------
void PhyRegAlloc::addInterf4PseudoInstr(const MachineInstr *MInst) {
bool setInterf = false;
// iterate over MI operands to find defs
for (MachineInstr::const_val_op_iterator It1 = MInst->begin(),
ItE = MInst->end(); It1 != ItE; ++It1) {
const LiveRange *LROfOp1 = LRI->getLiveRangeForValue(*It1);
assert((LROfOp1 || !It1.isUseOnly())&&"No LR for Def in PSEUDO insruction");
MachineInstr::const_val_op_iterator It2 = It1;
for (++It2; It2 != ItE; ++It2) {
const LiveRange *LROfOp2 = LRI->getLiveRangeForValue(*It2);
if (LROfOp2) {
RegClass *RCOfOp1 = LROfOp1->getRegClass();
RegClass *RCOfOp2 = LROfOp2->getRegClass();
if (RCOfOp1 == RCOfOp2 ){
RCOfOp1->setInterference( LROfOp1, LROfOp2 );
setInterf = true;
}
} // if Op2 has a LR
} // for all other defs in machine instr
} // for all operands in an instruction
if (!setInterf && MInst->getNumOperands() > 2) {
std::cerr << "\nInterf not set for any operand in pseudo instr:\n";
std::cerr << *MInst;
assert(0 && "Interf not set for pseudo instr with > 2 operands" );
}
}
//----------------------------------------------------------------------------
// This method adds interferences for incoming arguments to a function.
//----------------------------------------------------------------------------
void PhyRegAlloc::addInterferencesForArgs() {
// get the InSet of root BB
const ValueSet &InSet = LVI->getInSetOfBB(&Fn->front());
for (Function::const_aiterator AI = Fn->abegin(); AI != Fn->aend(); ++AI) {
// add interferences between args and LVars at start
addInterference(AI, &InSet, false);
if (DEBUG_RA >= RA_DEBUG_Interference)
std::cerr << " - %% adding interference for argument " << RAV(AI) << "\n";
}
}
//----------------------------------------------------------------------------
// This method is called after register allocation is complete to set the
// allocated registers in the machine code. This code will add register numbers
// to MachineOperands that contain a Value. Also it calls target specific
// methods to produce caller saving instructions. At the end, it adds all
// additional instructions produced by the register allocator to the
// instruction stream.
//----------------------------------------------------------------------------
//-----------------------------
// Utility functions used below
//-----------------------------
inline void
InsertBefore(MachineInstr* newMI,
MachineBasicBlock& MBB,
MachineBasicBlock::iterator& MII)
{
MII = MBB.insert(MII, newMI);
++MII;
}
inline void
InsertAfter(MachineInstr* newMI,
MachineBasicBlock& MBB,
MachineBasicBlock::iterator& MII)
{
++MII; // insert before the next instruction
MII = MBB.insert(MII, newMI);
}
inline void
DeleteInstruction(MachineBasicBlock& MBB,
MachineBasicBlock::iterator& MII)
{
MII = MBB.erase(MII);
}
inline void
SubstituteInPlace(MachineInstr* newMI,
MachineBasicBlock& MBB,
MachineBasicBlock::iterator MII)
{
*MII = newMI;
}
inline void
PrependInstructions(std::vector<MachineInstr *> &IBef,
MachineBasicBlock& MBB,
MachineBasicBlock::iterator& MII,
const std::string& msg)
{
if (!IBef.empty())
{
MachineInstr* OrigMI = *MII;
std::vector<MachineInstr *>::iterator AdIt;
for (AdIt = IBef.begin(); AdIt != IBef.end() ; ++AdIt)
{
if (DEBUG_RA) {
if (OrigMI) std::cerr << "For MInst:\n " << *OrigMI;
std::cerr << msg << "PREPENDed instr:\n " << **AdIt << "\n";
}
InsertBefore(*AdIt, MBB, MII);
}
}
}
inline void
AppendInstructions(std::vector<MachineInstr *> &IAft,
MachineBasicBlock& MBB,
MachineBasicBlock::iterator& MII,
const std::string& msg)
{
if (!IAft.empty())
{
MachineInstr* OrigMI = *MII;
std::vector<MachineInstr *>::iterator AdIt;
for ( AdIt = IAft.begin(); AdIt != IAft.end() ; ++AdIt )
{
if (DEBUG_RA) {
if (OrigMI) std::cerr << "For MInst:\n " << *OrigMI;
std::cerr << msg << "APPENDed instr:\n " << **AdIt << "\n";
}
InsertAfter(*AdIt, MBB, MII);
}
}
}
bool PhyRegAlloc::markAllocatedRegs(MachineInstr* MInst)
{
bool instrNeedsSpills = false;
// First, set the registers for operands in the machine instruction
// if a register was successfully allocated. Do this first because we
// will need to know which registers are already used by this instr'n.
for (unsigned OpNum=0; OpNum < MInst->getNumOperands(); ++OpNum)
{
MachineOperand& Op = MInst->getOperand(OpNum);
if (Op.getType() == MachineOperand::MO_VirtualRegister ||
Op.getType() == MachineOperand::MO_CCRegister)
{
const Value *const Val = Op.getVRegValue();
if (const LiveRange* LR = LRI->getLiveRangeForValue(Val)) {
// Remember if any operand needs spilling
instrNeedsSpills |= LR->isMarkedForSpill();
// An operand may have a color whether or not it needs spilling
if (LR->hasColor())
MInst->SetRegForOperand(OpNum,
MRI.getUnifiedRegNum(LR->getRegClass()->getID(),
LR->getColor()));
}
}
} // for each operand
return instrNeedsSpills;
}
void PhyRegAlloc::updateInstruction(MachineBasicBlock::iterator& MII,
MachineBasicBlock &MBB)
{
MachineInstr* MInst = *MII;
unsigned Opcode = MInst->getOpCode();
// Reset tmp stack positions so they can be reused for each machine instr.
MF->getInfo()->popAllTempValues();
// Mark the operands for which regs have been allocated.
bool instrNeedsSpills = markAllocatedRegs(*MII);
#ifndef NDEBUG
// Mark that the operands have been updated. Later,
// setRelRegsUsedByThisInst() is called to find registers used by each
// MachineInst, and it should not be used for an instruction until
// this is done. This flag just serves as a sanity check.
OperandsColoredMap[MInst] = true;
#endif
// Now insert caller-saving code before/after the call.
// Do this before inserting spill code since some registers must be
// used by save/restore and spill code should not use those registers.
if (TM.getInstrInfo().isCall(Opcode)) {
AddedInstrns &AI = AddedInstrMap[MInst];
insertCallerSavingCode(AI.InstrnsBefore, AI.InstrnsAfter, MInst,
MBB.getBasicBlock());
}
// Now insert spill code for remaining operands not allocated to
// registers. This must be done even for call return instructions
// since those are not handled by the special code above.
if (instrNeedsSpills)
for (unsigned OpNum=0; OpNum < MInst->getNumOperands(); ++OpNum)
{
MachineOperand& Op = MInst->getOperand(OpNum);
if (Op.getType() == MachineOperand::MO_VirtualRegister ||
Op.getType() == MachineOperand::MO_CCRegister)
{
const Value* Val = Op.getVRegValue();
if (const LiveRange *LR = LRI->getLiveRangeForValue(Val))
if (LR->isMarkedForSpill())
insertCode4SpilledLR(LR, MII, MBB, OpNum);
}
} // for each operand
}
void PhyRegAlloc::updateMachineCode()
{
// Insert any instructions needed at method entry
MachineBasicBlock::iterator MII = MF->front().begin();
PrependInstructions(AddedInstrAtEntry.InstrnsBefore, MF->front(), MII,
"At function entry: \n");
assert(AddedInstrAtEntry.InstrnsAfter.empty() &&
"InstrsAfter should be unnecessary since we are just inserting at "
"the function entry point here.");
for (MachineFunction::iterator BBI = MF->begin(), BBE = MF->end();
BBI != BBE; ++BBI) {
MachineBasicBlock &MBB = *BBI;
// Iterate over all machine instructions in BB and mark operands with
// their assigned registers or insert spill code, as appropriate.
// Also, fix operands of call/return instructions.
for (MachineBasicBlock::iterator MII = MBB.begin(); MII != MBB.end(); ++MII)
if (! TM.getInstrInfo().isDummyPhiInstr((*MII)->getOpCode()))
updateInstruction(MII, MBB);
// Now, move code out of delay slots of branches and returns if needed.
// (Also, move "after" code from calls to the last delay slot instruction.)
// Moving code out of delay slots is needed in 2 situations:
// (1) If this is a branch and it needs instructions inserted after it,
// move any existing instructions out of the delay slot so that the
// instructions can go into the delay slot. This only supports the
// case that #instrsAfter <= #delay slots.
//
// (2) If any instruction in the delay slot needs
// instructions inserted, move it out of the delay slot and before the
// branch because putting code before or after it would be VERY BAD!
//
// If the annul bit of the branch is set, neither of these is legal!
// If so, we need to handle spill differently but annulling is not yet used.
for (MachineBasicBlock::iterator MII = MBB.begin();
MII != MBB.end(); ++MII)
if (unsigned delaySlots =
TM.getInstrInfo().getNumDelaySlots((*MII)->getOpCode()))
{
MachineInstr *MInst = *MII, *DelaySlotMI = *(MII+1);
// Check the 2 conditions above:
// (1) Does a branch need instructions added after it?
// (2) O/w does delay slot instr. need instrns before or after?
bool isBranch = (TM.getInstrInfo().isBranch(MInst->getOpCode()) ||
TM.getInstrInfo().isReturn(MInst->getOpCode()));
bool cond1 = (isBranch &&
AddedInstrMap.count(MInst) &&
AddedInstrMap[MInst].InstrnsAfter.size() > 0);
bool cond2 = (AddedInstrMap.count(DelaySlotMI) &&
(AddedInstrMap[DelaySlotMI].InstrnsBefore.size() > 0 ||
AddedInstrMap[DelaySlotMI].InstrnsAfter.size() > 0));
if (cond1 || cond2)
{
assert((MInst->getOpCodeFlags() & AnnulFlag) == 0 &&
"FIXME: Moving an annulled delay slot instruction!");
assert(delaySlots==1 &&
"InsertBefore does not yet handle >1 delay slots!");
InsertBefore(DelaySlotMI, MBB, MII); // MII pts back to branch
// In case (1), delete it and don't replace with anything!
// Otherwise (i.e., case (2) only) replace it with a NOP.
if (cond1) {
DeleteInstruction(MBB, ++MII); // MII now points to next inst.
--MII; // reset MII for ++MII of loop
}
else
SubstituteInPlace(BuildMI(TM.getInstrInfo().getNOPOpCode(),1),
MBB, MII+1); // replace with NOP
if (DEBUG_RA) {
std::cerr << "\nRegAlloc: Moved instr. with added code: "
<< *DelaySlotMI
<< " out of delay slots of instr: " << *MInst;
}
}
else
// For non-branch instr with delay slots (probably a call), move
// InstrAfter to the instr. in the last delay slot.
move2DelayedInstr(*MII, *(MII+delaySlots));
}
// Finally iterate over all instructions in BB and insert before/after
for (MachineBasicBlock::iterator MII=MBB.begin(); MII != MBB.end(); ++MII) {
MachineInstr *MInst = *MII;
// do not process Phis
if (TM.getInstrInfo().isDummyPhiInstr(MInst->getOpCode()))
continue;
// if there are any added instructions...
if (AddedInstrMap.count(MInst)) {
AddedInstrns &CallAI = AddedInstrMap[MInst];
#ifndef NDEBUG
bool isBranch = (TM.getInstrInfo().isBranch(MInst->getOpCode()) ||
TM.getInstrInfo().isReturn(MInst->getOpCode()));
assert((!isBranch ||
AddedInstrMap[MInst].InstrnsAfter.size() <=
TM.getInstrInfo().getNumDelaySlots(MInst->getOpCode())) &&
"Cannot put more than #delaySlots instrns after "
"branch or return! Need to handle temps differently.");
#endif
#ifndef NDEBUG
// Temporary sanity checking code to detect whether the same machine
// instruction is ever inserted twice before/after a call.
// I suspect this is happening but am not sure. --Vikram, 7/1/03.
std::set<const MachineInstr*> instrsSeen;
for (int i = 0, N = CallAI.InstrnsBefore.size(); i < N; ++i) {
assert(instrsSeen.count(CallAI.InstrnsBefore[i]) == 0 &&
"Duplicate machine instruction in InstrnsBefore!");
instrsSeen.insert(CallAI.InstrnsBefore[i]);
}
for (int i = 0, N = CallAI.InstrnsAfter.size(); i < N; ++i) {
assert(instrsSeen.count(CallAI.InstrnsAfter[i]) == 0 &&
"Duplicate machine instruction in InstrnsBefore/After!");
instrsSeen.insert(CallAI.InstrnsAfter[i]);
}
#endif
// Now add the instructions before/after this MI.
// We do this here to ensure that spill for an instruction is inserted
// as close as possible to an instruction (see above insertCode4Spill)
if (! CallAI.InstrnsBefore.empty())
PrependInstructions(CallAI.InstrnsBefore, MBB, MII,"");
if (! CallAI.InstrnsAfter.empty())
AppendInstructions(CallAI.InstrnsAfter, MBB, MII,"");
} // if there are any added instructions
} // for each machine instruction
}
}
//----------------------------------------------------------------------------
// This method inserts spill code for AN operand whose LR was spilled.
// This method may be called several times for a single machine instruction
// if it contains many spilled operands. Each time it is called, it finds
// a register which is not live at that instruction and also which is not
// used by other spilled operands of the same instruction. Then it uses
// this register temporarily to accommodate the spilled value.
//----------------------------------------------------------------------------
void PhyRegAlloc::insertCode4SpilledLR(const LiveRange *LR,
MachineBasicBlock::iterator& MII,
MachineBasicBlock &MBB,
const unsigned OpNum) {
MachineInstr *MInst = *MII;
const BasicBlock *BB = MBB.getBasicBlock();
assert((! TM.getInstrInfo().isCall(MInst->getOpCode()) || OpNum == 0) &&
"Outgoing arg of a call must be handled elsewhere (func arg ok)");
assert(! TM.getInstrInfo().isReturn(MInst->getOpCode()) &&
"Return value of a ret must be handled elsewhere");
MachineOperand& Op = MInst->getOperand(OpNum);
bool isDef = Op.opIsDefOnly();
bool isDefAndUse = Op.opIsDefAndUse();
unsigned RegType = MRI.getRegTypeForLR(LR);
int SpillOff = LR->getSpillOffFromFP();
RegClass *RC = LR->getRegClass();
// Get the live-variable set to find registers free before this instr.
const ValueSet &LVSetBef = LVI->getLiveVarSetBeforeMInst(MInst, BB);
#ifndef NDEBUG
// If this instr. is in the delay slot of a branch or return, we need to
// include all live variables before that branch or return -- we don't want to
// trample those! Verify that the set is included in the LV set before MInst.
if (MII != MBB.begin()) {
MachineInstr *PredMI = *(MII-1);
if (unsigned DS = TM.getInstrInfo().getNumDelaySlots(PredMI->getOpCode()))
assert(set_difference(LVI->getLiveVarSetBeforeMInst(PredMI), LVSetBef)
.empty() && "Live-var set before branch should be included in "
"live-var set of each delay slot instruction!");
}
#endif
MF->getInfo()->pushTempValue(MRI.getSpilledRegSize(RegType) );
std::vector<MachineInstr*> MIBef, MIAft;
std::vector<MachineInstr*> AdIMid;
// Choose a register to hold the spilled value, if one was not preallocated.
// This may insert code before and after MInst to free up the value. If so,
// this code should be first/last in the spill sequence before/after MInst.
int TmpRegU=(LR->hasColor()
? MRI.getUnifiedRegNum(LR->getRegClass()->getID(),LR->getColor())
: getUsableUniRegAtMI(RegType, &LVSetBef, MInst, MIBef,MIAft));
// Set the operand first so that it this register does not get used
// as a scratch register for later calls to getUsableUniRegAtMI below
MInst->SetRegForOperand(OpNum, TmpRegU);
// get the added instructions for this instruction
AddedInstrns &AI = AddedInstrMap[MInst];
// We may need a scratch register to copy the spilled value to/from memory.
// This may itself have to insert code to free up a scratch register.
// Any such code should go before (after) the spill code for a load (store).
// The scratch reg is not marked as used because it is only used
// for the copy and not used across MInst.
int scratchRegType = -1;
int scratchReg = -1;
if (MRI.regTypeNeedsScratchReg(RegType, scratchRegType))
{
scratchReg = getUsableUniRegAtMI(scratchRegType, &LVSetBef,
MInst, MIBef, MIAft);
assert(scratchReg != MRI.getInvalidRegNum());
}
if (!isDef || isDefAndUse) {
// for a USE, we have to load the value of LR from stack to a TmpReg
// and use the TmpReg as one operand of instruction
// actual loading instruction(s)
MRI.cpMem2RegMI(AdIMid, MRI.getFramePointer(), SpillOff, TmpRegU,
RegType, scratchReg);
// the actual load should be after the instructions to free up TmpRegU
MIBef.insert(MIBef.end(), AdIMid.begin(), AdIMid.end());
AdIMid.clear();
}
if (isDef || isDefAndUse) { // if this is a Def
// for a DEF, we have to store the value produced by this instruction
// on the stack position allocated for this LR
// actual storing instruction(s)
MRI.cpReg2MemMI(AdIMid, TmpRegU, MRI.getFramePointer(), SpillOff,
RegType, scratchReg);
MIAft.insert(MIAft.begin(), AdIMid.begin(), AdIMid.end());
} // if !DEF
// Finally, insert the entire spill code sequences before/after MInst
AI.InstrnsBefore.insert(AI.InstrnsBefore.end(), MIBef.begin(), MIBef.end());
AI.InstrnsAfter.insert(AI.InstrnsAfter.begin(), MIAft.begin(), MIAft.end());
if (DEBUG_RA) {
std::cerr << "\nFor Inst:\n " << *MInst;
std::cerr << "SPILLED LR# " << LR->getUserIGNode()->getIndex();
std::cerr << "; added Instructions:";
for_each(MIBef.begin(), MIBef.end(), std::mem_fun(&MachineInstr::dump));
for_each(MIAft.begin(), MIAft.end(), std::mem_fun(&MachineInstr::dump));
}
}
//----------------------------------------------------------------------------
// This method inserts caller saving/restoring instructions before/after
// a call machine instruction. The caller saving/restoring instructions are
// inserted like:
// ** caller saving instructions
// other instructions inserted for the call by ColorCallArg
// CALL instruction
// other instructions inserted for the call ColorCallArg
// ** caller restoring instructions
//----------------------------------------------------------------------------
void
PhyRegAlloc::insertCallerSavingCode(std::vector<MachineInstr*> &instrnsBefore,
std::vector<MachineInstr*> &instrnsAfter,
MachineInstr *CallMI,
const BasicBlock *BB)
{
assert(TM.getInstrInfo().isCall(CallMI->getOpCode()));
// hash set to record which registers were saved/restored
hash_set<unsigned> PushedRegSet;
CallArgsDescriptor* argDesc = CallArgsDescriptor::get(CallMI);
// if the call is to a instrumentation function, do not insert save and
// restore instructions the instrumentation function takes care of save
// restore for volatile regs.
//
// FIXME: this should be made general, not specific to the reoptimizer!
const Function *Callee = argDesc->getCallInst()->getCalledFunction();
bool isLLVMFirstTrigger = Callee && Callee->getName() == "llvm_first_trigger";
// Now check if the call has a return value (using argDesc) and if so,
// find the LR of the TmpInstruction representing the return value register.
// (using the last or second-last *implicit operand* of the call MI).
// Insert it to to the PushedRegSet since we must not save that register
// and restore it after the call.
// We do this because, we look at the LV set *after* the instruction
// to determine, which LRs must be saved across calls. The return value
// of the call is live in this set - but we must not save/restore it.
if (const Value *origRetVal = argDesc->getReturnValue()) {
unsigned retValRefNum = (CallMI->getNumImplicitRefs() -
(argDesc->getIndirectFuncPtr()? 1 : 2));
const TmpInstruction* tmpRetVal =
cast<TmpInstruction>(CallMI->getImplicitRef(retValRefNum));
assert(tmpRetVal->getOperand(0) == origRetVal &&
tmpRetVal->getType() == origRetVal->getType() &&
"Wrong implicit ref?");
LiveRange *RetValLR = LRI->getLiveRangeForValue(tmpRetVal);
assert(RetValLR && "No LR for RetValue of call");
if (! RetValLR->isMarkedForSpill())
PushedRegSet.insert(MRI.getUnifiedRegNum(RetValLR->getRegClassID(),
RetValLR->getColor()));
}
const ValueSet &LVSetAft = LVI->getLiveVarSetAfterMInst(CallMI, BB);
ValueSet::const_iterator LIt = LVSetAft.begin();
// for each live var in live variable set after machine inst
for( ; LIt != LVSetAft.end(); ++LIt) {
// get the live range corresponding to live var
LiveRange *const LR = LRI->getLiveRangeForValue(*LIt);
// LR can be null if it is a const since a const
// doesn't have a dominating def - see Assumptions above
if( LR ) {
if(! LR->isMarkedForSpill()) {
assert(LR->hasColor() && "LR is neither spilled nor colored?");
unsigned RCID = LR->getRegClassID();
unsigned Color = LR->getColor();
if (MRI.isRegVolatile(RCID, Color) ) {
// if this is a call to the first-level reoptimizer
// instrumentation entry point, and the register is not
// modified by call, don't save and restore it.
if (isLLVMFirstTrigger && !MRI.modifiedByCall(RCID, Color))
continue;
// if the value is in both LV sets (i.e., live before and after
// the call machine instruction)
unsigned Reg = MRI.getUnifiedRegNum(RCID, Color);
// if we haven't already pushed this register...
if( PushedRegSet.find(Reg) == PushedRegSet.end() ) {
unsigned RegType = MRI.getRegTypeForLR(LR);
// Now get two instructions - to push on stack and pop from stack
// and add them to InstrnsBefore and InstrnsAfter of the
// call instruction
int StackOff =
MF->getInfo()->pushTempValue(MRI.getSpilledRegSize(RegType));
//---- Insert code for pushing the reg on stack ----------
std::vector<MachineInstr*> AdIBef, AdIAft;
// We may need a scratch register to copy the saved value
// to/from memory. This may itself have to insert code to
// free up a scratch register. Any such code should go before
// the save code. The scratch register, if any, is by default
// temporary and not "used" by the instruction unless the
// copy code itself decides to keep the value in the scratch reg.
int scratchRegType = -1;
int scratchReg = -1;
if (MRI.regTypeNeedsScratchReg(RegType, scratchRegType))
{ // Find a register not live in the LVSet before CallMI
const ValueSet &LVSetBef =
LVI->getLiveVarSetBeforeMInst(CallMI, BB);
scratchReg = getUsableUniRegAtMI(scratchRegType, &LVSetBef,
CallMI, AdIBef, AdIAft);
assert(scratchReg != MRI.getInvalidRegNum());
}
if (AdIBef.size() > 0)
instrnsBefore.insert(instrnsBefore.end(),
AdIBef.begin(), AdIBef.end());
MRI.cpReg2MemMI(instrnsBefore, Reg, MRI.getFramePointer(),
StackOff, RegType, scratchReg);
if (AdIAft.size() > 0)
instrnsBefore.insert(instrnsBefore.end(),
AdIAft.begin(), AdIAft.end());
//---- Insert code for popping the reg from the stack ----------
AdIBef.clear();
AdIAft.clear();
// We may need a scratch register to copy the saved value
// from memory. This may itself have to insert code to
// free up a scratch register. Any such code should go
// after the save code. As above, scratch is not marked "used".
scratchRegType = -1;
scratchReg = -1;
if (MRI.regTypeNeedsScratchReg(RegType, scratchRegType))
{ // Find a register not live in the LVSet after CallMI
scratchReg = getUsableUniRegAtMI(scratchRegType, &LVSetAft,
CallMI, AdIBef, AdIAft);
assert(scratchReg != MRI.getInvalidRegNum());
}
if (AdIBef.size() > 0)
instrnsAfter.insert(instrnsAfter.end(),
AdIBef.begin(), AdIBef.end());
MRI.cpMem2RegMI(instrnsAfter, MRI.getFramePointer(), StackOff,
Reg, RegType, scratchReg);
if (AdIAft.size() > 0)
instrnsAfter.insert(instrnsAfter.end(),
AdIAft.begin(), AdIAft.end());
PushedRegSet.insert(Reg);
if(DEBUG_RA) {
std::cerr << "\nFor call inst:" << *CallMI;
std::cerr << " -inserted caller saving instrs: Before:\n\t ";
for_each(instrnsBefore.begin(), instrnsBefore.end(),
std::mem_fun(&MachineInstr::dump));
std::cerr << " -and After:\n\t ";
for_each(instrnsAfter.begin(), instrnsAfter.end(),
std::mem_fun(&MachineInstr::dump));
}
} // if not already pushed
} // if LR has a volatile color
} // if LR has color
} // if there is a LR for Var
} // for each value in the LV set after instruction
}
//----------------------------------------------------------------------------
// We can use the following method to get a temporary register to be used
// BEFORE any given machine instruction. If there is a register available,
// this method will simply return that register and set MIBef = MIAft = NULL.
// Otherwise, it will return a register and MIAft and MIBef will contain
// two instructions used to free up this returned register.
// Returned register number is the UNIFIED register number
//----------------------------------------------------------------------------
int PhyRegAlloc::getUsableUniRegAtMI(const int RegType,
const ValueSet *LVSetBef,
MachineInstr *MInst,
std::vector<MachineInstr*>& MIBef,
std::vector<MachineInstr*>& MIAft) {
RegClass* RC = getRegClassByID(MRI.getRegClassIDOfRegType(RegType));
int RegU = getUnusedUniRegAtMI(RC, RegType, MInst, LVSetBef);
if (RegU == -1) {
// we couldn't find an unused register. Generate code to free up a reg by
// saving it on stack and restoring after the instruction
int TmpOff = MF->getInfo()->pushTempValue(MRI.getSpilledRegSize(RegType));
RegU = getUniRegNotUsedByThisInst(RC, RegType, MInst);
// Check if we need a scratch register to copy this register to memory.
int scratchRegType = -1;
if (MRI.regTypeNeedsScratchReg(RegType, scratchRegType))
{
int scratchReg = getUsableUniRegAtMI(scratchRegType, LVSetBef,
MInst, MIBef, MIAft);
assert(scratchReg != MRI.getInvalidRegNum());
// We may as well hold the value in the scratch register instead
// of copying it to memory and back. But we have to mark the
// register as used by this instruction, so it does not get used
// as a scratch reg. by another operand or anyone else.
ScratchRegsUsed.insert(std::make_pair(MInst, scratchReg));
MRI.cpReg2RegMI(MIBef, RegU, scratchReg, RegType);
MRI.cpReg2RegMI(MIAft, scratchReg, RegU, RegType);
}
else
{ // the register can be copied directly to/from memory so do it.
MRI.cpReg2MemMI(MIBef, RegU, MRI.getFramePointer(), TmpOff, RegType);
MRI.cpMem2RegMI(MIAft, MRI.getFramePointer(), TmpOff, RegU, RegType);
}
}
return RegU;
}
//----------------------------------------------------------------------------
// This method is called to get a new unused register that can be used
// to accommodate a temporary value. This method may be called several times
// for a single machine instruction. Each time it is called, it finds a
// register which is not live at that instruction and also which is not used
// by other spilled operands of the same instruction. Return register number
// is relative to the register class, NOT the unified number.
//----------------------------------------------------------------------------
int PhyRegAlloc::getUnusedUniRegAtMI(RegClass *RC,
const int RegType,
const MachineInstr *MInst,
const ValueSet* LVSetBef) {
RC->clearColorsUsed(); // Reset array
if (LVSetBef == NULL) {
LVSetBef = &LVI->getLiveVarSetBeforeMInst(MInst);
assert(LVSetBef != NULL && "Unable to get live-var set before MInst?");
}
ValueSet::const_iterator LIt = LVSetBef->begin();
// for each live var in live variable set after machine inst
for ( ; LIt != LVSetBef->end(); ++LIt) {
// Get the live range corresponding to live var, and its RegClass
LiveRange *const LRofLV = LRI->getLiveRangeForValue(*LIt );
// LR can be null if it is a const since a const
// doesn't have a dominating def - see Assumptions above
if (LRofLV && LRofLV->getRegClass() == RC && LRofLV->hasColor())
RC->markColorsUsed(LRofLV->getColor(),
MRI.getRegTypeForLR(LRofLV), RegType);
}
// It is possible that one operand of this MInst was already spilled
// and it received some register temporarily. If that's the case,
// it is recorded in machine operand. We must skip such registers.
setRelRegsUsedByThisInst(RC, RegType, MInst);
int unusedReg = RC->getUnusedColor(RegType); // find first unused color
if (unusedReg >= 0)
return MRI.getUnifiedRegNum(RC->getID(), unusedReg);
return -1;
}
//----------------------------------------------------------------------------
// Get any other register in a register class, other than what is used
// by operands of a machine instruction. Returns the unified reg number.
//----------------------------------------------------------------------------
int PhyRegAlloc::getUniRegNotUsedByThisInst(RegClass *RC,
const int RegType,
const MachineInstr *MInst) {
RC->clearColorsUsed();
setRelRegsUsedByThisInst(RC, RegType, MInst);
// find the first unused color
int unusedReg = RC->getUnusedColor(RegType);
assert(unusedReg >= 0 &&
"FATAL: No free register could be found in reg class!!");
return MRI.getUnifiedRegNum(RC->getID(), unusedReg);
}
//----------------------------------------------------------------------------
// This method modifies the IsColorUsedArr of the register class passed to it.
// It sets the bits corresponding to the registers used by this machine
// instructions. Both explicit and implicit operands are set.
//----------------------------------------------------------------------------
static void markRegisterUsed(int RegNo, RegClass *RC, int RegType,
const TargetRegInfo &TRI) {
unsigned classId = 0;
int classRegNum = TRI.getClassRegNum(RegNo, classId);
if (RC->getID() == classId)
RC->markColorsUsed(classRegNum, RegType, RegType);
}
void PhyRegAlloc::setRelRegsUsedByThisInst(RegClass *RC, int RegType,
const MachineInstr *MI)
{
assert(OperandsColoredMap[MI] == true &&
"Illegal to call setRelRegsUsedByThisInst() until colored operands "
"are marked for an instruction.");
// Add the registers already marked as used by the instruction.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
if (MI->getOperand(i).hasAllocatedReg())
markRegisterUsed(MI->getOperand(i).getAllocatedRegNum(), RC, RegType,MRI);
for (unsigned i = 0, e = MI->getNumImplicitRefs(); i != e; ++i)
if (MI->getImplicitOp(i).hasAllocatedReg())
markRegisterUsed(MI->getImplicitOp(i).getAllocatedRegNum(), RC,
RegType,MRI);
// Add all of the scratch registers that are used to save values across the
// instruction (e.g., for saving state register values).
std::pair<ScratchRegsUsedTy::iterator, ScratchRegsUsedTy::iterator>
IR = ScratchRegsUsed.equal_range(MI);
for (ScratchRegsUsedTy::iterator I = IR.first; I != IR.second; ++I)
markRegisterUsed(I->second, RC, RegType, MRI);
// If there are implicit references, mark their allocated regs as well
for (unsigned z=0; z < MI->getNumImplicitRefs(); z++)
if (const LiveRange*
LRofImpRef = LRI->getLiveRangeForValue(MI->getImplicitRef(z)))
if (LRofImpRef->hasColor())
// this implicit reference is in a LR that received a color
RC->markColorsUsed(LRofImpRef->getColor(),
MRI.getRegTypeForLR(LRofImpRef), RegType);
}
//----------------------------------------------------------------------------
// If there are delay slots for an instruction, the instructions
// added after it must really go after the delayed instruction(s).
// So, we move the InstrAfter of that instruction to the
// corresponding delayed instruction using the following method.
//----------------------------------------------------------------------------
void PhyRegAlloc::move2DelayedInstr(const MachineInstr *OrigMI,
const MachineInstr *DelayedMI)
{
// "added after" instructions of the original instr
std::vector<MachineInstr *> &OrigAft = AddedInstrMap[OrigMI].InstrnsAfter;
if (DEBUG_RA && OrigAft.size() > 0) {
std::cerr << "\nRegAlloc: Moved InstrnsAfter for: " << *OrigMI;
std::cerr << " to last delay slot instrn: " << *DelayedMI;
}
// "added after" instructions of the delayed instr
std::vector<MachineInstr *> &DelayedAft=AddedInstrMap[DelayedMI].InstrnsAfter;
// go thru all the "added after instructions" of the original instruction
// and append them to the "added after instructions" of the delayed
// instructions
DelayedAft.insert(DelayedAft.end(), OrigAft.begin(), OrigAft.end());
// empty the "added after instructions" of the original instruction
OrigAft.clear();
}
void PhyRegAlloc::colorIncomingArgs()
{
MRI.colorMethodArgs(Fn, *LRI, AddedInstrAtEntry.InstrnsBefore,
AddedInstrAtEntry.InstrnsAfter);
}
//----------------------------------------------------------------------------
// This method calls setSugColorUsable method of each live range. This
// will determine whether the suggested color of LR is really usable.
// A suggested color is not usable when the suggested color is volatile
// AND when there are call interferences
//----------------------------------------------------------------------------
void PhyRegAlloc::markUnusableSugColors()
{
LiveRangeMapType::const_iterator HMI = (LRI->getLiveRangeMap())->begin();
LiveRangeMapType::const_iterator HMIEnd = (LRI->getLiveRangeMap())->end();
for (; HMI != HMIEnd ; ++HMI ) {
if (HMI->first) {
LiveRange *L = HMI->second; // get the LiveRange
if (L) {
if (L->hasSuggestedColor()) {
int RCID = L->getRegClass()->getID();
if (MRI.isRegVolatile( RCID, L->getSuggestedColor()) &&
L->isCallInterference() )
L->setSuggestedColorUsable( false );
else
L->setSuggestedColorUsable( true );
}
} // if L->hasSuggestedColor()
}
} // for all LR's in hash map
}
//----------------------------------------------------------------------------
// The following method will set the stack offsets of the live ranges that
// are decided to be spilled. This must be called just after coloring the
// LRs using the graph coloring algo. For each live range that is spilled,
// this method allocate a new spill position on the stack.
//----------------------------------------------------------------------------
void PhyRegAlloc::allocateStackSpace4SpilledLRs() {
if (DEBUG_RA) std::cerr << "\nSetting LR stack offsets for spills...\n";
LiveRangeMapType::const_iterator HMI = LRI->getLiveRangeMap()->begin();
LiveRangeMapType::const_iterator HMIEnd = LRI->getLiveRangeMap()->end();
for ( ; HMI != HMIEnd ; ++HMI) {
if (HMI->first && HMI->second) {
LiveRange *L = HMI->second; // get the LiveRange
if (L->isMarkedForSpill()) { // NOTE: allocating size of long Type **
int stackOffset = MF->getInfo()->allocateSpilledValue(Type::LongTy);
L->setSpillOffFromFP(stackOffset);
if (DEBUG_RA)
std::cerr << " LR# " << L->getUserIGNode()->getIndex()
<< ": stack-offset = " << stackOffset << "\n";
}
}
} // for all LR's in hash map
}
//----------------------------------------------------------------------------
// The entry point to Register Allocation
//----------------------------------------------------------------------------
bool PhyRegAlloc::runOnFunction (Function &F) {
if (DEBUG_RA)
std::cerr << "\n********* Function "<< F.getName () << " ***********\n";
Fn = &F;
MF = &MachineFunction::get (Fn);
LVI = &getAnalysis<FunctionLiveVarInfo> ();
LRI = new LiveRangeInfo (Fn, TM, RegClassList);
LoopDepthCalc = &getAnalysis<LoopInfo> ();
// Create each RegClass for the target machine and add it to the
// RegClassList. This must be done before calling constructLiveRanges().
for (unsigned rc = 0; rc != NumOfRegClasses; ++rc)
RegClassList.push_back (new RegClass (Fn, &TM.getRegInfo (),
MRI.getMachineRegClass (rc)));
LRI->constructLiveRanges(); // create LR info
if (DEBUG_RA >= RA_DEBUG_LiveRanges)
LRI->printLiveRanges();
createIGNodeListsAndIGs(); // create IGNode list and IGs
buildInterferenceGraphs(); // build IGs in all reg classes
if (DEBUG_RA >= RA_DEBUG_LiveRanges) {
// print all LRs in all reg classes
for ( unsigned rc=0; rc < NumOfRegClasses ; rc++)
RegClassList[rc]->printIGNodeList();
// print IGs in all register classes
for ( unsigned rc=0; rc < NumOfRegClasses ; rc++)
RegClassList[rc]->printIG();
}
LRI->coalesceLRs(); // coalesce all live ranges
if (DEBUG_RA >= RA_DEBUG_LiveRanges) {
// print all LRs in all reg classes
for (unsigned rc=0; rc < NumOfRegClasses; rc++)
RegClassList[rc]->printIGNodeList();
// print IGs in all register classes
for (unsigned rc=0; rc < NumOfRegClasses; rc++)
RegClassList[rc]->printIG();
}
// mark un-usable suggested color before graph coloring algorithm.
// When this is done, the graph coloring algo will not reserve
// suggested color unnecessarily - they can be used by another LR
markUnusableSugColors();
// color all register classes using the graph coloring algo
for (unsigned rc=0; rc < NumOfRegClasses ; rc++)
RegClassList[rc]->colorAllRegs();
// After graph coloring, if some LRs did not receive a color (i.e, spilled)
// a position for such spilled LRs
allocateStackSpace4SpilledLRs();
// Reset the temp. area on the stack before use by the first instruction.
// This will also happen after updating each instruction.
MF->getInfo()->popAllTempValues();
// color incoming args - if the correct color was not received
// insert code to copy to the correct register
colorIncomingArgs();
// Now update the machine code with register names and add any
// additional code inserted by the register allocator to the instruction
// stream
updateMachineCode();
if (DEBUG_RA) {
std::cerr << "\n**** Machine Code After Register Allocation:\n\n";
MF->dump();
}
// Tear down temporary data structures
for (unsigned rc = 0; rc < NumOfRegClasses; ++rc)
delete RegClassList[rc];
RegClassList.clear ();
AddedInstrMap.clear ();
OperandsColoredMap.clear ();
ScratchRegsUsed.clear ();
AddedInstrAtEntry.clear ();
delete LRI;
if (DEBUG_RA) std::cerr << "\nRegister allocation complete!\n";
return false; // Function was not modified
}
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