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/// exactly one predecessor and the control transfer mechanism between
/// the predecessor and this block is a fall-through.
bool AsmPrinter::
isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
// If this is a landing pad, it isn't a fall through. If it has no preds,
// then nothing falls through to it.
if (MBB->isLandingPad() || MBB->pred_empty())
return false;
// If there isn't exactly one predecessor, it can't be a fall through.
MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(), PI2 = PI;
++PI2;
if (PI2 != MBB->pred_end())
return false;
// The predecessor has to be immediately before this block.
MachineBasicBlock *Pred = *PI;
if (!Pred->isLayoutSuccessor(MBB))
return false;
// If the block is completely empty, then it definitely does fall through.
if (Pred->empty())
return true;
// Check the terminators in the previous blocks
for (MachineBasicBlock::iterator II = Pred->getFirstTerminator(),
IE = Pred->end(); II != IE; ++II) {
MachineInstr &MI = *II;
// If it is not a simple branch, we are in a table somewhere.
if (!MI.getDesc().isBranch() || MI.getDesc().isIndirectBranch())
return false;
// If we are the operands of one of the branches, this is not
// a fall through.
for (MachineInstr::mop_iterator OI = MI.operands_begin(),
OE = MI.operands_end(); OI != OE; ++OI) {
const MachineOperand& OP = *OI;
if (OP.isJTI())
return false;
if (OP.isMBB() && OP.getMBB() == MBB)
return false;
}
}
return true;
}
GCMetadataPrinter *AsmPrinter::GetOrCreateGCPrinter(GCStrategy *S) {
if (!S->usesMetadata())
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return 0;
gcp_map_type &GCMap = getGCMap(GCMetadataPrinters);
gcp_map_type::iterator GCPI = GCMap.find(S);
if (GCPI != GCMap.end())
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return GCPI->second;
const char *Name = S->getName().c_str();
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for (GCMetadataPrinterRegistry::iterator
I = GCMetadataPrinterRegistry::begin(),
E = GCMetadataPrinterRegistry::end(); I != E; ++I)
if (strcmp(Name, I->getName()) == 0) {
GCMetadataPrinter *GMP = I->instantiate();
GMP->S = S;
GCMap.insert(std::make_pair(S, GMP));
return GMP;
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}
report_fatal_error("no GCMetadataPrinter registered for GC: " + Twine(Name));
return 0;
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}