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Fix some brittle code. Watch out for cases where register scavenger is pointing to deleted instructions.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34998 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-03-07 02:38:05 +00:00
parent f262b35559
commit 0ea12ec848
1 changed files with 39 additions and 41 deletions
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80
lib/Target/ARM/ARMLoadStoreOptimizer.cpp
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@ -40,6 +40,7 @@ namespace {
const TargetInstrInfo *TII;
const MRegisterInfo *MRI;
RegScavenger *RS;
MachineBasicBlock::iterator RSI;
virtual bool runOnMachineFunction(MachineFunction &Fn);
@ -59,11 +60,10 @@ namespace {
typedef SmallVector<MemOpQueueEntry,8> MemOpQueue;
typedef MemOpQueue::iterator MemOpQueueIter;
void AdvanceRS(MachineBasicBlock *MBB, MemOpQueue &MemOps);
SmallVector<MachineBasicBlock::iterator, 4>
MergeLDR_STR(MachineBasicBlock &MBB, unsigned SIndex, unsigned Base,
int Opcode, unsigned Size, MemOpQueue &MemOps);
int Opcode, unsigned Size, unsigned Scratch,
MemOpQueue &MemOps);
bool LoadStoreMultipleOpti(MachineBasicBlock &MBB);
bool MergeReturnIntoLDM(MachineBasicBlock &MBB);
@ -106,8 +106,8 @@ static int getLoadStoreMultipleOpcode(int Opcode) {
/// It returns true if the transformation is done.
static bool mergeOps(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
int Offset, unsigned Base, bool BaseKill, int Opcode,
unsigned Scratch,
SmallVector<std::pair<unsigned, bool>, 8> &Regs,
RegScavenger *RS,
const TargetInstrInfo *TII) {
// Only a single register to load / store. Don't bother.
unsigned NumRegs = Regs.size();
@ -135,8 +135,8 @@ static bool mergeOps(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
// use as the new base.
NewBase = Regs[NumRegs-1].first;
else {
// Try to find a free register to use as a new base.
NewBase = RS ? RS->FindUnusedReg(&ARM::GPRRegClass) : (unsigned)ARM::R12;
// Use the scratch register to use as a new base.
NewBase = Scratch;
if (NewBase == 0)
return false;
}
@ -169,31 +169,12 @@ static bool mergeOps(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
return true;
}
/// AdvanceRS - Advance register scavenger to just before the earliest memory
/// op that is being merged.
void ARMLoadStoreOpt::AdvanceRS(MachineBasicBlock *MBB, MemOpQueue &MemOps) {
MachineBasicBlock::iterator Loc = MemOps[0].MBBI;
unsigned Position = MemOps[0].Position;
for (unsigned i = 1, e = MemOps.size(); i != e; ++i) {
if (MemOps[i].Position < Position) {
Position = MemOps[i].Position;
Loc = MemOps[i].MBBI;
}
}
if (Loc != MBB->begin())
RS->forward(prior(Loc));
}
/// MergeLDR_STR - Merge a number of load / store instructions into one or more
/// load / store multiple instructions.
SmallVector<MachineBasicBlock::iterator, 4>
ARMLoadStoreOpt::MergeLDR_STR(MachineBasicBlock &MBB,
unsigned SIndex, unsigned Base, int Opcode,
unsigned Size, MemOpQueue &MemOps) {
if (RS && SIndex == 0)
AdvanceRS(&MBB, MemOps);
ARMLoadStoreOpt::MergeLDR_STR(MachineBasicBlock &MBB, unsigned SIndex,
unsigned Base, int Opcode, unsigned Size,
unsigned Scratch, MemOpQueue &MemOps) {
SmallVector<MachineBasicBlock::iterator, 4> Merges;
SmallVector<std::pair<unsigned,bool>, 8> Regs;
bool isAM4 = Opcode == ARM::LDR || Opcode == ARM::STR;
@ -219,7 +200,7 @@ ARMLoadStoreOpt::MergeLDR_STR(MachineBasicBlock &MBB,
PRegNum = RegNum;
} else {
// Can't merge this in. Try merge the earlier ones first.
if (mergeOps(MBB, ++Loc, SOffset, Base, false, Opcode, Regs, RS, TII)) {
if (mergeOps(MBB, ++Loc, SOffset, Base, false, Opcode,Scratch,Regs,TII)) {
Merges.push_back(prior(Loc));
for (unsigned j = SIndex; j < i; ++j) {
MBB.erase(MemOps[j].MBBI);
@ -227,7 +208,7 @@ ARMLoadStoreOpt::MergeLDR_STR(MachineBasicBlock &MBB,
}
}
SmallVector<MachineBasicBlock::iterator, 4> Merges2 =
MergeLDR_STR(MBB, i, Base, Opcode, Size, MemOps);
MergeLDR_STR(MBB, i, Base, Opcode, Size, Scratch, MemOps);
Merges.append(Merges2.begin(), Merges2.end());
return Merges;
}
@ -239,7 +220,7 @@ ARMLoadStoreOpt::MergeLDR_STR(MachineBasicBlock &MBB,
}
bool BaseKill = Loc->findRegisterUseOperand(Base, true) != NULL;
if (mergeOps(MBB, ++Loc, SOffset, Base, BaseKill, Opcode, Regs, RS, TII)) {
if (mergeOps(MBB, ++Loc, SOffset, Base, BaseKill, Opcode,Scratch,Regs, TII)) {
Merges.push_back(prior(Loc));
for (unsigned i = SIndex, e = MemOps.size(); i != e; ++i) {
MBB.erase(MemOps[i].MBBI);
@ -520,7 +501,8 @@ bool ARMLoadStoreOpt::LoadStoreMultipleOpti(MachineBasicBlock &MBB) {
unsigned CurrSize = 0;
unsigned Position = 0;
if (RS) RS->enterBasicBlock(&MBB);
RS->enterBasicBlock(&MBB);
RSI = MBB.begin();
MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
while (MBBI != E) {
bool Advance = false;
@ -600,22 +582,38 @@ bool ARMLoadStoreOpt::LoadStoreMultipleOpti(MachineBasicBlock &MBB) {
if (TryMerge) {
if (NumMemOps > 1) {
// Try to find a free register to use as a new base in case it's needed.
unsigned Scratch = ARM::R12;
// First advance to the instruction just before the start of the chain.
if (RSI != MBB.begin())
RS->forward(prior(RSI));
// Find a scratch register.
Scratch = RS->FindUnusedReg(&ARM::GPRRegClass);
// Process the load / store instructions.
RS->forward(prior(MBBI));
// Merge ops.
SmallVector<MachineBasicBlock::iterator,4> MBBII =
MergeLDR_STR(MBB, 0, CurrBase, CurrOpc, CurrSize, MemOps);
MergeLDR_STR(MBB, 0, CurrBase, CurrOpc, CurrSize, Scratch, MemOps);
// Try folding preceeding/trailing base inc/dec into the generated
// LDM/STM ops.
for (unsigned i = 0, e = MBBII.size(); i < e; ++i)
if (mergeBaseUpdateLSMultiple(MBB, MBBII[i]))
NumMerges++;
NumMerges += MBBII.size();
}
// Try folding preceeding/trailing base inc/dec into those load/store
// that were not merged to form LDM/STM ops.
for (unsigned i = 0; i != NumMemOps; ++i)
if (!MemOps[i].Merged)
if (mergeBaseUpdateLoadStore(MBB, MemOps[i].MBBI, TII))
NumMerges++;
// Try folding preceeding/trailing base inc/dec into those load/store
// that were not merged to form LDM/STM ops.
for (unsigned i = 0; i != NumMemOps; ++i)
if (!MemOps[i].Merged)
if (mergeBaseUpdateLoadStore(MBB, MemOps[i].MBBI, TII))
NumMerges++;
// RS may be pointing to an instruction that's deleted.
RS->skipTo(prior(MBBI));
RSI = MBBI;
}
CurrBase = 0;
CurrOpc = -1;
@ -665,7 +663,7 @@ bool ARMLoadStoreOpt::runOnMachineFunction(MachineFunction &Fn) {
const TargetMachine &TM = Fn.getTarget();
TII = TM.getInstrInfo();
MRI = TM.getRegisterInfo();
RS = MRI->requiresRegisterScavenging(Fn) ? new RegScavenger() : NULL;
RS = new RegScavenger();
bool Modified = false;
for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E;