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Spiller now remove unused spill slots.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47657 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2008-02-27 03:04:06 +00:00
parent 1953ecb0a6
commit d36531249a
8 changed files with 132 additions and 23 deletions
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22
include/llvm/CodeGen/MachineFrameInfo.h
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@ -80,7 +80,8 @@ class MachineFrameInfo {
// StackObject - Represent a single object allocated on the stack.
struct StackObject {
// The size of this object on the stack. 0 means a variable sized object
// The size of this object on the stack. 0 means a variable sized object,
// ~0ULL means a dead object.
uint64_t Size;
// Alignment - The required alignment of this stack slot.
@ -292,6 +293,14 @@ public:
return Objects[ObjectIdx+NumFixedObjects].isImmutable;
}
/// isDeadObjectIndex - Returns true if the specified index corresponds to
/// a dead object.
bool isDeadObjectIndex(int ObjectIdx) const {
assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
"Invalid Object Idx!");
return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL;
}
/// CreateStackObject - Create a new statically sized stack object, returning
/// a postive identifier to represent it.
///
@ -304,6 +313,17 @@ public:
return Objects.size()-NumFixedObjects-1;
}
/// RemoveStackObject - Remove or mark dead a statically sized stack object.
///
void RemoveStackObject(int ObjectIdx) {
if (ObjectIdx == (int)(Objects.size()-NumFixedObjects-1))
// Last object, simply pop it off the list.
Objects.pop_back();
else
// Mark it dead.
Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL;
}
/// CreateVariableSizedObject - Notify the MachineFrameInfo object that a
/// variable sized object has been created. This must be created whenever a
/// variable sized object is created, whether or not the index returned is

3
lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -764,6 +764,9 @@ bool LiveIntervals::tryFoldMemoryOperand(MachineInstr* &MI,
MachineInstr *fmi = isSS ? tii_->foldMemoryOperand(*mf_, MI, FoldOps, Slot)
: tii_->foldMemoryOperand(*mf_, MI, FoldOps, DefMI);
if (fmi) {
// Remember this instruction uses the spill slot.
if (isSS) vrm.addSpillSlotUse(Slot, fmi);
// Attempt to fold the memory reference into the instruction. If
// we can do this, we don't need to insert spill code.
if (lv_)

4
lib/CodeGen/MachineFunction.cpp
View File

@ -350,6 +350,10 @@ void MachineFrameInfo::print(const MachineFunction &MF, std::ostream &OS) const{
for (unsigned i = 0, e = Objects.size(); i != e; ++i) {
const StackObject &SO = Objects[i];
OS << " <fi #" << (int)(i-NumFixedObjects) << ">: ";
if (SO.Size == ~0ULL) {
OS << "dead\n";
continue;
}
if (SO.Size == 0)
OS << "variable sized";
else

2
lib/CodeGen/PrologEpilogInserter.cpp
View File

@ -406,6 +406,8 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
continue;
if (RS && (int)i == RS->getScavengingFrameIndex())
continue;
if (FFI->isDeadObjectIndex(i))
continue;
// If stack grows down, we need to add size of find the lowest
// address of the object.

89
lib/CodeGen/VirtRegMap.cpp
View File

@ -42,6 +42,7 @@ STATISTIC(NumLoads , "Number of loads added");
STATISTIC(NumReused, "Number of values reused");
STATISTIC(NumDSE , "Number of dead stores elided");
STATISTIC(NumDCE , "Number of copies elided");
STATISTIC(NumDSS , "Number of dead spill slots removed");
namespace {
enum SpillerName { simple, local };
@ -64,7 +65,9 @@ VirtRegMap::VirtRegMap(MachineFunction &mf)
: TII(*mf.getTarget().getInstrInfo()), MF(mf),
Virt2PhysMap(NO_PHYS_REG), Virt2StackSlotMap(NO_STACK_SLOT),
Virt2ReMatIdMap(NO_STACK_SLOT), Virt2SplitMap(0),
Virt2SplitKillMap(0), ReMatMap(NULL), ReMatId(MAX_STACK_SLOT+1) {
Virt2SplitKillMap(0), ReMatMap(NULL), ReMatId(MAX_STACK_SLOT+1),
LowSpillSlot(NO_STACK_SLOT), HighSpillSlot(NO_STACK_SLOT) {
SpillSlotToUsesMap.resize(8);
grow();
}
@ -83,21 +86,28 @@ int VirtRegMap::assignVirt2StackSlot(unsigned virtReg) {
assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
"attempt to assign stack slot to already spilled register");
const TargetRegisterClass* RC = MF.getRegInfo().getRegClass(virtReg);
int frameIndex = MF.getFrameInfo()->CreateStackObject(RC->getSize(),
RC->getAlignment());
Virt2StackSlotMap[virtReg] = frameIndex;
int SS = MF.getFrameInfo()->CreateStackObject(RC->getSize(),
RC->getAlignment());
if (LowSpillSlot == NO_STACK_SLOT)
LowSpillSlot = SS;
if (HighSpillSlot == NO_STACK_SLOT || SS > HighSpillSlot)
HighSpillSlot = SS;
unsigned Idx = SS-LowSpillSlot;
while (Idx >= SpillSlotToUsesMap.size())
SpillSlotToUsesMap.resize(SpillSlotToUsesMap.size()*2);
Virt2StackSlotMap[virtReg] = SS;
++NumSpills;
return frameIndex;
return SS;
}
void VirtRegMap::assignVirt2StackSlot(unsigned virtReg, int frameIndex) {
void VirtRegMap::assignVirt2StackSlot(unsigned virtReg, int SS) {
assert(TargetRegisterInfo::isVirtualRegister(virtReg));
assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
"attempt to assign stack slot to already spilled register");
assert((frameIndex >= 0 ||
(frameIndex >= MF.getFrameInfo()->getObjectIndexBegin())) &&
assert((SS >= 0 ||
(SS >= MF.getFrameInfo()->getObjectIndexBegin())) &&
"illegal fixed frame index");
Virt2StackSlotMap[virtReg] = frameIndex;
Virt2StackSlotMap[virtReg] = SS;
}
int VirtRegMap::assignVirtReMatId(unsigned virtReg) {
@ -115,6 +125,13 @@ void VirtRegMap::assignVirtReMatId(unsigned virtReg, int id) {
Virt2ReMatIdMap[virtReg] = id;
}
void VirtRegMap::addSpillSlotUse(int FI, MachineInstr *MI) {
if (!MF.getFrameInfo()->isFixedObjectIndex(FI)) {
assert(FI >= 0 && "Spill slot index should not be negative!");
SpillSlotToUsesMap[FI-LowSpillSlot].insert(MI);
}
}
void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *OldMI,
MachineInstr *NewMI, ModRef MRInfo) {
// Move previous memory references folded to new instruction.
@ -134,6 +151,21 @@ void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *MI, ModRef MRInfo) {
MI2VirtMap.insert(IP, std::make_pair(MI, std::make_pair(VirtReg, MRInfo)));
}
void VirtRegMap::RemoveMachineInstrFromMaps(MachineInstr *MI) {
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isFrameIndex())
continue;
int FI = MO.getIndex();
if (MF.getFrameInfo()->isFixedObjectIndex(FI))
continue;
SpillSlotToUsesMap[FI-LowSpillSlot].erase(MI);
}
MI2VirtMap.erase(MI);
SpillPt2VirtMap.erase(MI);
RestorePt2VirtMap.erase(MI);
}
void VirtRegMap::print(std::ostream &OS) const {
const TargetRegisterInfo* TRI = MF.getTarget().getRegisterInfo();
@ -204,14 +236,18 @@ bool SimpleSpiller::runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
std::find(LoadedRegs.begin(), LoadedRegs.end(), VirtReg)
== LoadedRegs.end()) {
TII.loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
MachineInstr *LoadMI = prior(MII);
VRM.addSpillSlotUse(StackSlot, LoadMI);
LoadedRegs.push_back(VirtReg);
++NumLoads;
DOUT << '\t' << *prior(MII);
DOUT << '\t' << *LoadMI;
}
if (MO.isDef()) {
TII.storeRegToStackSlot(MBB, next(MII), PhysReg, true,
StackSlot, RC);
MachineInstr *StoreMI = next(MII);
VRM.addSpillSlotUse(StackSlot, StoreMI);
++NumStores;
}
}
@ -260,6 +296,16 @@ namespace {
MBB != E; ++MBB)
RewriteMBB(*MBB, VRM);
// Mark unused spill slots.
MachineFrameInfo *MFI = MF.getFrameInfo();
int SS = VRM.getLowSpillSlot();
if (SS != VirtRegMap::NO_STACK_SLOT)
for (int e = VRM.getHighSpillSlot(); SS <= e; ++SS)
if (!VRM.isSpillSlotUsed(SS)) {
MFI->RemoveStackObject(SS);
++NumDSS;
}
DOUT << "**** Post Machine Instrs ****\n";
DEBUG(MF.dump());
@ -725,6 +771,8 @@ namespace {
} else {
TII->loadRegFromStackSlot(*MBB, MII, NewPhysReg,
NewOp.StackSlotOrReMat, AliasRC);
MachineInstr *LoadMI = prior(MII);
VRM.addSpillSlotUse(NewOp.StackSlotOrReMat, LoadMI);
// Any stores to this stack slot are not dead anymore.
MaybeDeadStores[NewOp.StackSlotOrReMat] = NULL;
++NumLoads;
@ -906,7 +954,9 @@ void LocalSpiller::SpillRegToStackSlot(MachineBasicBlock &MBB,
std::vector<MachineOperand*> &KillOps,
VirtRegMap &VRM) {
TII->storeRegToStackSlot(MBB, next(MII), PhysReg, true, StackSlot, RC);
DOUT << "Store:\t" << *next(MII);
MachineInstr *StoreMI = next(MII);
VRM.addSpillSlotUse(StackSlot, StoreMI);
DOUT << "Store:\t" << *StoreMI;
// If there is a dead store to this stack slot, nuke it now.
if (LastStore) {
@ -918,8 +968,8 @@ void LocalSpiller::SpillRegToStackSlot(MachineBasicBlock &MBB,
bool CheckDef = PrevMII != MBB.begin();
if (CheckDef)
--PrevMII;
MBB.erase(LastStore);
VRM.RemoveMachineInstrFromMaps(LastStore);
MBB.erase(LastStore);
if (CheckDef) {
// Look at defs of killed registers on the store. Mark the defs
// as dead since the store has been deleted and they aren't
@ -931,8 +981,8 @@ void LocalSpiller::SpillRegToStackSlot(MachineBasicBlock &MBB,
if (ReMatDefs.count(DeadDef) && !HasOtherDef) {
// FIXME: This assumes a remat def does not have side
// effects.
MBB.erase(DeadDef);
VRM.RemoveMachineInstrFromMaps(DeadDef);
MBB.erase(DeadDef);
++NumDRM;
}
}
@ -1006,8 +1056,10 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
ReMaterialize(MBB, MII, Phys, VirtReg, TRI, VRM);
} else {
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
TII->loadRegFromStackSlot(MBB, &MI, Phys, VRM.getStackSlot(VirtReg),
RC);
int SS = VRM.getStackSlot(VirtReg);
TII->loadRegFromStackSlot(MBB, &MI, Phys, SS, RC);
MachineInstr *LoadMI = prior(MII);
VRM.addSpillSlotUse(SS, LoadMI);
++NumLoads;
}
// This invalidates Phys.
@ -1031,6 +1083,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
int StackSlot = VRM.getStackSlot(VirtReg);
TII->storeRegToStackSlot(MBB, next(MII), Phys, isKill, StackSlot, RC);
MachineInstr *StoreMI = next(MII);
VRM.addSpillSlotUse(StackSlot, StoreMI);
DOUT << "Store:\t" << StoreMI;
VRM.virtFolded(VirtReg, StoreMI, VirtRegMap::isMod);
}
@ -1257,6 +1310,8 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
} else {
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
TII->loadRegFromStackSlot(MBB, &MI, PhysReg, SSorRMId, RC);
MachineInstr *LoadMI = prior(MII);
VRM.addSpillSlotUse(SSorRMId, LoadMI);
++NumLoads;
}
// This invalidates PhysReg.
@ -1431,9 +1486,9 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
++NumDCE;
DOUT << "Removing now-noop copy: " << MI;
VRM.RemoveMachineInstrFromMaps(&MI);
MBB.erase(&MI);
Erased = true;
VRM.RemoveMachineInstrFromMaps(&MI);
Spills.disallowClobberPhysReg(VirtReg);
goto ProcessNextInst;
}
@ -1507,9 +1562,9 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
++NumDCE;
DOUT << "Removing now-noop copy: " << MI;
VRM.RemoveMachineInstrFromMaps(&MI);
MBB.erase(&MI);
Erased = true;
VRM.RemoveMachineInstrFromMaps(&MI);
UpdateKills(*LastStore, RegKills, KillOps);
goto ProcessNextInst;
}

32
lib/CodeGen/VirtRegMap.h
View File

@ -20,6 +20,7 @@
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/IndexedMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Support/Streams.h"
#include <map>
@ -98,6 +99,12 @@ namespace llvm {
/// conflicts with stack slot numbers.
int ReMatId;
/// LowSpillSlot, HighSpillSlot - Lowest and highest spill slot indexes.
int LowSpillSlot, HighSpillSlot;
/// SpillSlotToUsesMap - Records uses for each register spill slot.
SmallVector<SmallPtrSet<MachineInstr*, 4>, 8> SpillSlotToUsesMap;
VirtRegMap(const VirtRegMap&); // DO NOT IMPLEMENT
void operator=(const VirtRegMap&); // DO NOT IMPLEMENT
@ -299,6 +306,25 @@ namespace llvm {
RestorePt2VirtMap.erase(I);
}
/// @brief Return lowest spill slot index.
int getLowSpillSlot() const {
return LowSpillSlot;
}
/// @brief Return highest spill slot index.
int getHighSpillSlot() const {
return HighSpillSlot;
}
/// @brief Records a spill slot use.
void addSpillSlotUse(int FrameIndex, MachineInstr *MI);
/// @brief Returns true if spill slot has been used.
bool isSpillSlotUsed(int FrameIndex) const {
assert(FrameIndex >= 0 && "Spill slot index should not be negative!");
return !SpillSlotToUsesMap[FrameIndex-LowSpillSlot].empty();
}
/// @brief Updates information about the specified virtual register's value
/// folded into newMI machine instruction.
void virtFolded(unsigned VirtReg, MachineInstr *OldMI, MachineInstr *NewMI,
@ -317,11 +343,7 @@ namespace llvm {
/// RemoveMachineInstrFromMaps - MI is being erased, remove it from the
/// the folded instruction map and spill point map.
void RemoveMachineInstrFromMaps(MachineInstr *MI) {
MI2VirtMap.erase(MI);
SpillPt2VirtMap.erase(MI);
RestorePt2VirtMap.erase(MI);
}
void RemoveMachineInstrFromMaps(MachineInstr *MI);
void print(std::ostream &OS) const;
void print(std::ostream *OS) const { if (OS) print(*OS); }

2
lib/Target/ARM/ARMRegisterInfo.cpp
View File

@ -870,6 +870,8 @@ static unsigned estimateStackSize(MachineFunction &MF, MachineFrameInfo *MFI) {
if (FixedOff > Offset) Offset = FixedOff;
}
for (unsigned i = 0, e = FFI->getObjectIndexEnd(); i != e; ++i) {
if (FFI->isDeadObjectIndex(i))
continue;
Offset += FFI->getObjectSize(i);
unsigned Align = FFI->getObjectAlignment(i);
// Adjust to alignment boundary

1
test/CodeGen/X86/2008-02-22-ReMatBug.ll
View File

@ -1,4 +1,5 @@
; RUN: llvm-as < %s | llc -march=x86 -stats |& grep {Number of re-materialization} | grep 3
; RUN: llvm-as < %s | llc -march=x86 -stats |& grep {Number of dead spill slots removed}
; rdar://5761454
%struct.quad_struct = type { i32, i32, %struct.quad_struct*, %struct.quad_struct*, %struct.quad_struct*, %struct.quad_struct*, %struct.quad_struct* }