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//===- MachineLoopInfo.cpp - Natural Loop Calculator ----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the MachineLoopInfo class that is used to identify natural
// loops and determine the loop depth of various nodes of the CFG. Note that
// the loops identified may actually be several natural loops that share the
// same header node... not just a single natural loop.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/Analysis/LoopInfoImpl.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
// Explicitly instantiate methods in LoopInfoImpl.h for MI-level Loops.
template class llvm::LoopBase<MachineBasicBlock, MachineLoop>;
template class llvm::LoopInfoBase<MachineBasicBlock, MachineLoop>;
char MachineLoopInfo::ID = 0;
INITIALIZE_PASS_BEGIN(MachineLoopInfo, "machine-loops",
"Machine Natural Loop Construction", true, true)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_END(MachineLoopInfo, "machine-loops",
"Machine Natural Loop Construction", true, true)
char &llvm::MachineLoopInfoID = MachineLoopInfo::ID;
bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) {
releaseMemory();
LI.Analyze(getAnalysis<MachineDominatorTree>().getBase());
return false;
}
void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<MachineDominatorTree>();
MachineFunctionPass::getAnalysisUsage(AU);
}
MachineBasicBlock *MachineLoop::getTopBlock() {
MachineBasicBlock *TopMBB = getHeader();
MachineFunction::iterator Begin = TopMBB->getParent()->begin();
if (TopMBB != Begin) {
MachineBasicBlock *PriorMBB = std::prev(MachineFunction::iterator(TopMBB));
while (contains(PriorMBB)) {
TopMBB = PriorMBB;
if (TopMBB == Begin) break;
PriorMBB = std::prev(MachineFunction::iterator(TopMBB));
}
}
return TopMBB;
}
MachineBasicBlock *MachineLoop::getBottomBlock() {
MachineBasicBlock *BotMBB = getHeader();
MachineFunction::iterator End = BotMBB->getParent()->end();
if (BotMBB != std::prev(End)) {
MachineBasicBlock *NextMBB = std::next(MachineFunction::iterator(BotMBB));
while (contains(NextMBB)) {
BotMBB = NextMBB;
if (BotMBB == std::next(MachineFunction::iterator(BotMBB))) break;
NextMBB = std::next(MachineFunction::iterator(BotMBB));
}
}
return BotMBB;
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void MachineLoop::dump() const {
print(dbgs());
}
#endif
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