PHIEliminationUtils.cpp [plain text]
#include "PHIEliminationUtils.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/ADT/SmallPtrSet.h"
using namespace llvm;
MachineBasicBlock::iterator
llvm::findPHICopyInsertPoint(MachineBasicBlock* MBB, MachineBasicBlock* SuccMBB,
unsigned SrcReg) {
if (MBB->empty())
return MBB->begin();
if (!SuccMBB->isLandingPad())
return MBB->getFirstTerminator();
SmallPtrSet<MachineInstr*, 8> DefUsesInMBB;
MachineRegisterInfo& MRI = MBB->getParent()->getRegInfo();
for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(SrcReg),
RE = MRI.reg_end(); RI != RE; ++RI) {
MachineInstr* DefUseMI = &*RI;
if (DefUseMI->getParent() == MBB)
DefUsesInMBB.insert(DefUseMI);
}
MachineBasicBlock::iterator InsertPoint;
if (DefUsesInMBB.empty()) {
InsertPoint = MBB->begin();
} else if (DefUsesInMBB.size() == 1) {
InsertPoint = *DefUsesInMBB.begin();
++InsertPoint;
} else {
InsertPoint = MBB->end();
while (!DefUsesInMBB.count(&*--InsertPoint)) {}
++InsertPoint;
}
return MBB->SkipPHIsAndLabels(InsertPoint);
}