llvm/lib/CodeGen/Spiller.cpp
Lang Hames ffd1326ff8 Improved tracking of value number kills. VN kills are now represented
as an (index,bool) pair. The bool flag records whether the kill is a
PHI kill or not. This code will be used to enable splitting of live
intervals containing PHI-kills.

A slight change to live interval weights introduced an extra spill
into lsr-code-insertion (outside the critical sections). The test 
condition has been updated to reflect this.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75097 91177308-0d34-0410-b5e6-96231b3b80d8
2009-07-09 03:57:02 +00:00

367 lines
12 KiB
C++

//===-- llvm/CodeGen/Spiller.cpp - Spiller -------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "spiller"
#include "Spiller.h"
#include "VirtRegMap.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/LiveStackAnalysis.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
Spiller::~Spiller() {}
namespace {
/// Utility class for spillers.
class SpillerBase : public Spiller {
protected:
MachineFunction *mf;
LiveIntervals *lis;
LiveStacks *ls;
MachineFrameInfo *mfi;
MachineRegisterInfo *mri;
const TargetInstrInfo *tii;
VirtRegMap *vrm;
/// Construct a spiller base.
SpillerBase(MachineFunction *mf, LiveIntervals *lis, LiveStacks *ls,
VirtRegMap *vrm) :
mf(mf), lis(lis), ls(ls), vrm(vrm)
{
mfi = mf->getFrameInfo();
mri = &mf->getRegInfo();
tii = mf->getTarget().getInstrInfo();
}
/// Ensures there is space before the given machine instruction, returns the
/// instruction's new number.
unsigned makeSpaceBefore(MachineInstr *mi) {
if (!lis->hasGapBeforeInstr(lis->getInstructionIndex(mi))) {
lis->scaleNumbering(2);
ls->scaleNumbering(2);
}
unsigned miIdx = lis->getInstructionIndex(mi);
assert(lis->hasGapBeforeInstr(miIdx));
return miIdx;
}
/// Ensure there is space after the given machine instruction, returns the
/// instruction's new number.
unsigned makeSpaceAfter(MachineInstr *mi) {
if (!lis->hasGapAfterInstr(lis->getInstructionIndex(mi))) {
lis->scaleNumbering(2);
ls->scaleNumbering(2);
}
unsigned miIdx = lis->getInstructionIndex(mi);
assert(lis->hasGapAfterInstr(miIdx));
return miIdx;
}
/// Insert a store of the given vreg to the given stack slot immediately
/// after the given instruction. Returns the base index of the inserted
/// instruction. The caller is responsible for adding an appropriate
/// LiveInterval to the LiveIntervals analysis.
unsigned insertStoreAfter(MachineInstr *mi, unsigned ss,
unsigned vreg,
const TargetRegisterClass *trc) {
MachineBasicBlock::iterator nextInstItr(next(mi));
unsigned miIdx = makeSpaceAfter(mi);
tii->storeRegToStackSlot(*mi->getParent(), nextInstItr, vreg,
true, ss, trc);
MachineBasicBlock::iterator storeInstItr(next(mi));
MachineInstr *storeInst = &*storeInstItr;
unsigned storeInstIdx = miIdx + LiveInterval::InstrSlots::NUM;
assert(lis->getInstructionFromIndex(storeInstIdx) == 0 &&
"Store inst index already in use.");
lis->InsertMachineInstrInMaps(storeInst, storeInstIdx);
return storeInstIdx;
}
/// Insert a store of the given vreg to the given stack slot immediately
/// before the given instructnion. Returns the base index of the inserted
/// Instruction.
unsigned insertStoreBefore(MachineInstr *mi, unsigned ss,
unsigned vreg,
const TargetRegisterClass *trc) {
unsigned miIdx = makeSpaceBefore(mi);
tii->storeRegToStackSlot(*mi->getParent(), mi, vreg, true, ss, trc);
MachineBasicBlock::iterator storeInstItr(prior(mi));
MachineInstr *storeInst = &*storeInstItr;
unsigned storeInstIdx = miIdx - LiveInterval::InstrSlots::NUM;
assert(lis->getInstructionFromIndex(storeInstIdx) == 0 &&
"Store inst index already in use.");
lis->InsertMachineInstrInMaps(storeInst, storeInstIdx);
return storeInstIdx;
}
void insertStoreAfterInstOnInterval(LiveInterval *li,
MachineInstr *mi, unsigned ss,
unsigned vreg,
const TargetRegisterClass *trc) {
unsigned storeInstIdx = insertStoreAfter(mi, ss, vreg, trc);
unsigned start = lis->getDefIndex(lis->getInstructionIndex(mi)),
end = lis->getUseIndex(storeInstIdx);
VNInfo *vni =
li->getNextValue(storeInstIdx, 0, true, lis->getVNInfoAllocator());
li->addKill(vni, storeInstIdx, false);
DOUT << " Inserting store range: [" << start << ", " << end << ")\n";
LiveRange lr(start, end, vni);
li->addRange(lr);
}
/// Insert a load of the given vreg from the given stack slot immediately
/// after the given instruction. Returns the base index of the inserted
/// instruction. The caller is responsibel for adding/removing an appropriate
/// range vreg's LiveInterval.
unsigned insertLoadAfter(MachineInstr *mi, unsigned ss,
unsigned vreg,
const TargetRegisterClass *trc) {
MachineBasicBlock::iterator nextInstItr(next(mi));
unsigned miIdx = makeSpaceAfter(mi);
tii->loadRegFromStackSlot(*mi->getParent(), nextInstItr, vreg, ss, trc);
MachineBasicBlock::iterator loadInstItr(next(mi));
MachineInstr *loadInst = &*loadInstItr;
unsigned loadInstIdx = miIdx + LiveInterval::InstrSlots::NUM;
assert(lis->getInstructionFromIndex(loadInstIdx) == 0 &&
"Store inst index already in use.");
lis->InsertMachineInstrInMaps(loadInst, loadInstIdx);
return loadInstIdx;
}
/// Insert a load of the given vreg from the given stack slot immediately
/// before the given instruction. Returns the base index of the inserted
/// instruction. The caller is responsible for adding an appropriate
/// LiveInterval to the LiveIntervals analysis.
unsigned insertLoadBefore(MachineInstr *mi, unsigned ss,
unsigned vreg,
const TargetRegisterClass *trc) {
unsigned miIdx = makeSpaceBefore(mi);
tii->loadRegFromStackSlot(*mi->getParent(), mi, vreg, ss, trc);
MachineBasicBlock::iterator loadInstItr(prior(mi));
MachineInstr *loadInst = &*loadInstItr;
unsigned loadInstIdx = miIdx - LiveInterval::InstrSlots::NUM;
assert(lis->getInstructionFromIndex(loadInstIdx) == 0 &&
"Load inst index already in use.");
lis->InsertMachineInstrInMaps(loadInst, loadInstIdx);
return loadInstIdx;
}
void insertLoadBeforeInstOnInterval(LiveInterval *li,
MachineInstr *mi, unsigned ss,
unsigned vreg,
const TargetRegisterClass *trc) {
unsigned loadInstIdx = insertLoadBefore(mi, ss, vreg, trc);
unsigned start = lis->getDefIndex(loadInstIdx),
end = lis->getUseIndex(lis->getInstructionIndex(mi));
VNInfo *vni =
li->getNextValue(loadInstIdx, 0, true, lis->getVNInfoAllocator());
li->addKill(vni, lis->getInstructionIndex(mi), false);
DOUT << " Intserting load range: [" << start << ", " << end << ")\n";
LiveRange lr(start, end, vni);
li->addRange(lr);
}
/// Add spill ranges for every use/def of the live interval, inserting loads
/// immediately before each use, and stores after each def. No folding is
/// attempted.
std::vector<LiveInterval*> trivialSpillEverywhere(LiveInterval *li) {
DOUT << "Spilling everywhere " << *li << "\n";
assert(li->weight != HUGE_VALF &&
"Attempting to spill already spilled value.");
assert(!li->isStackSlot() &&
"Trying to spill a stack slot.");
DOUT << "Trivial spill everywhere of reg" << li->reg << "\n";
std::vector<LiveInterval*> added;
const TargetRegisterClass *trc = mri->getRegClass(li->reg);
unsigned ss = vrm->assignVirt2StackSlot(li->reg);
for (MachineRegisterInfo::reg_iterator
regItr = mri->reg_begin(li->reg); regItr != mri->reg_end();) {
MachineInstr *mi = &*regItr;
DOUT << " Processing " << *mi;
do {
++regItr;
} while (regItr != mri->reg_end() && (&*regItr == mi));
SmallVector<unsigned, 2> indices;
bool hasUse = false;
bool hasDef = false;
for (unsigned i = 0; i != mi->getNumOperands(); ++i) {
MachineOperand &op = mi->getOperand(i);
if (!op.isReg() || op.getReg() != li->reg)
continue;
hasUse |= mi->getOperand(i).isUse();
hasDef |= mi->getOperand(i).isDef();
indices.push_back(i);
}
unsigned newVReg = mri->createVirtualRegister(trc);
vrm->grow();
vrm->assignVirt2StackSlot(newVReg, ss);
LiveInterval *newLI = &lis->getOrCreateInterval(newVReg);
newLI->weight = HUGE_VALF;
for (unsigned i = 0; i < indices.size(); ++i) {
mi->getOperand(indices[i]).setReg(newVReg);
if (mi->getOperand(indices[i]).isUse()) {
mi->getOperand(indices[i]).setIsKill(true);
}
}
assert(hasUse || hasDef);
if (hasUse) {
insertLoadBeforeInstOnInterval(newLI, mi, ss, newVReg, trc);
}
if (hasDef) {
insertStoreAfterInstOnInterval(newLI, mi, ss, newVReg, trc);
}
added.push_back(newLI);
}
return added;
}
};
/// Spills any live range using the spill-everywhere method with no attempt at
/// folding.
class TrivialSpiller : public SpillerBase {
public:
TrivialSpiller(MachineFunction *mf, LiveIntervals *lis, LiveStacks *ls,
VirtRegMap *vrm) :
SpillerBase(mf, lis, ls, vrm) {}
std::vector<LiveInterval*> spill(LiveInterval *li) {
return trivialSpillEverywhere(li);
}
std::vector<LiveInterval*> intraBlockSplit(LiveInterval *li, VNInfo *valno) {
std::vector<LiveInterval*> spillIntervals;
if (!valno->isDefAccurate() && !valno->isPHIDef()) {
// Early out for values which have no well defined def point.
return spillIntervals;
}
// Ok.. we should be able to proceed...
const TargetRegisterClass *trc = mri->getRegClass(li->reg);
unsigned ss = vrm->assignVirt2StackSlot(li->reg);
vrm->grow();
vrm->assignVirt2StackSlot(li->reg, ss);
MachineInstr *mi = 0;
unsigned storeIdx = 0;
if (valno->isDefAccurate()) {
// If we have an accurate def we can just grab an iterator to the instr
// after the def.
mi = lis->getInstructionFromIndex(valno->def);
storeIdx = insertStoreAfter(mi, ss, li->reg, trc) +
LiveInterval::InstrSlots::DEF;
} else {
// if we get here we have a PHI def.
mi = &lis->getMBBFromIndex(valno->def)->front();
storeIdx = insertStoreBefore(mi, ss, li->reg, trc) +
LiveInterval::InstrSlots::DEF;
}
MachineBasicBlock *defBlock = mi->getParent();
unsigned loadIdx = 0;
// Now we need to find the load...
MachineBasicBlock::iterator useItr(mi);
for (; !useItr->readsRegister(li->reg); ++useItr) {}
if (useItr != defBlock->end()) {
MachineInstr *loadInst = useItr;
loadIdx = insertLoadBefore(loadInst, ss, li->reg, trc) +
LiveInterval::InstrSlots::USE;
}
else {
MachineInstr *loadInst = &defBlock->back();
loadIdx = insertLoadAfter(loadInst, ss, li->reg, trc) +
LiveInterval::InstrSlots::USE;
}
li->removeRange(storeIdx, loadIdx, true);
return spillIntervals;
}
};
}
llvm::Spiller* llvm::createSpiller(MachineFunction *mf, LiveIntervals *lis,
LiveStacks *ls, VirtRegMap *vrm) {
return new TrivialSpiller(mf, lis, ls, vrm);
}