#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/Dominators.h"
-#include "llvm/BasicBlock.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Assembly/Writer.h"
#include "Support/DepthFirstIterator.h"
#include <algorithm>
-AnalysisID cfg::LoopInfo::ID(AnalysisID::create<cfg::LoopInfo>());
+static RegisterAnalysis<LoopInfo>
+X("loops", "Natural Loop Construction", true);
//===----------------------------------------------------------------------===//
-// cfg::Loop implementation
+// Loop implementation
//
-bool cfg::Loop::contains(const BasicBlock *BB) const {
+bool Loop::contains(const BasicBlock *BB) const {
return find(Blocks.begin(), Blocks.end(), BB) != Blocks.end();
}
+bool Loop::isLoopExit(const BasicBlock *BB) const {
+ for (BasicBlock::succ_const_iterator SI = succ_begin(BB), SE = succ_end(BB);
+ SI != SE; ++SI) {
+ if (! contains(*SI))
+ return true;
+ }
+ return false;
+}
+
+unsigned Loop::getNumBackEdges() const {
+ unsigned numBackEdges = 0;
+ BasicBlock *header = Blocks.front();
+
+ for (std::vector<BasicBlock*>::const_iterator i = Blocks.begin(), e = Blocks.end();
+ i != e; ++i) {
+ for (BasicBlock::succ_iterator Successor = succ_begin(*i), SEnd = succ_end(*i);
+ Successor != SEnd; ++Successor) {
+ if (header == *Successor)
+ ++numBackEdges;
+ }
+ }
+ return numBackEdges;
+}
+
+void Loop::print(std::ostream &OS) const {
+ OS << std::string(getLoopDepth()*2, ' ') << "Loop Containing: ";
+
+ for (unsigned i = 0; i < getBlocks().size(); ++i) {
+ if (i) OS << ",";
+ WriteAsOperand(OS, (const Value*)getBlocks()[i]);
+ }
+ OS << "\n";
+
+ for (unsigned i = 0, e = getSubLoops().size(); i != e; ++i)
+ getSubLoops()[i]->print(OS);
+}
//===----------------------------------------------------------------------===//
-// cfg::LoopInfo implementation
+// LoopInfo implementation
//
-bool cfg::LoopInfo::runOnMethod(Method *M) {
- BBMap.clear(); // Reset internal state of analysis
- TopLevelLoops.clear();
+void LoopInfo::stub() {}
+
+bool LoopInfo::runOnFunction(Function &) {
+ releaseMemory();
Calculate(getAnalysis<DominatorSet>()); // Update
return false;
}
-void cfg::LoopInfo::Calculate(const DominatorSet &DS) {
- const BasicBlock *RootNode = DS.getRoot();
+void LoopInfo::releaseMemory() {
+ for (std::vector<Loop*>::iterator I = TopLevelLoops.begin(),
+ E = TopLevelLoops.end(); I != E; ++I)
+ delete *I; // Delete all of the loops...
- for (df_iterator<const BasicBlock*> NI = df_begin(RootNode),
+ BBMap.clear(); // Reset internal state of analysis
+ TopLevelLoops.clear();
+}
+
+
+void LoopInfo::Calculate(const DominatorSet &DS) {
+ BasicBlock *RootNode = DS.getRoot();
+
+ for (df_iterator<BasicBlock*> NI = df_begin(RootNode),
NE = df_end(RootNode); NI != NE; ++NI)
if (Loop *L = ConsiderForLoop(*NI, DS))
TopLevelLoops.push_back(L);
TopLevelLoops[i]->setLoopDepth(1);
}
-void cfg::LoopInfo::getAnalysisUsageInfo(Pass::AnalysisSet &Required,
- Pass::AnalysisSet &Destroyed,
- Pass::AnalysisSet &Provided) {
- Required.push_back(DominatorSet::ID);
- Provided.push_back(ID);
+void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+ AU.addRequired<DominatorSet>();
}
+void LoopInfo::print(std::ostream &OS) const {
+ for (unsigned i = 0; i < TopLevelLoops.size(); ++i)
+ TopLevelLoops[i]->print(OS);
+}
-cfg::Loop *cfg::LoopInfo::ConsiderForLoop(const BasicBlock *BB,
- const DominatorSet &DS) {
- if (BBMap.find(BB) != BBMap.end()) return 0; // Havn't processed this node?
+Loop *LoopInfo::ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS) {
+ if (BBMap.find(BB) != BBMap.end()) return 0; // Haven't processed this node?
- std::vector<const BasicBlock *> TodoStack;
+ std::vector<BasicBlock *> TodoStack;
// Scan the predecessors of BB, checking to see if BB dominates any of
// them.
- for (BasicBlock::pred_const_iterator I = BB->pred_begin(),
- E = BB->pred_end(); I != E; ++I)
+ for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I)
if (DS.dominates(BB, *I)) // If BB dominates it's predecessor...
TodoStack.push_back(*I);
BBMap[BB] = L;
while (!TodoStack.empty()) { // Process all the nodes in the loop
- const BasicBlock *X = TodoStack.back();
+ BasicBlock *X = TodoStack.back();
TodoStack.pop_back();
if (!L->contains(X)) { // As of yet unprocessed??
L->Blocks.push_back(X);
// Add all of the predecessors of X to the end of the work stack...
- TodoStack.insert(TodoStack.end(), X->pred_begin(), X->pred_end());
+ TodoStack.insert(TodoStack.end(), pred_begin(X), pred_end(X));
}
}
// loop can be found for them. Also check subsidary basic blocks to see if
// they start subloops of their own.
//
- for (std::vector<const BasicBlock*>::reverse_iterator I = L->Blocks.rbegin(),
+ for (std::vector<BasicBlock*>::reverse_iterator I = L->Blocks.rbegin(),
E = L->Blocks.rend(); I != E; ++I) {
// Check to see if this block starts a new loop
return L;
}
+
+/// getLoopPreheader - If there is a preheader for this loop, return it. A
+/// loop has a preheader if there is only one edge to the header of the loop
+/// from outside of the loop. If this is the case, the block branching to the
+/// header of the loop is the preheader node. The "preheaders" pass can be
+/// "Required" to ensure that there is always a preheader node for every loop.
+///
+/// This method returns null if there is no preheader for the loop (either
+/// because the loop is dead or because multiple blocks branch to the header
+/// node of this loop).
+///
+BasicBlock *Loop::getLoopPreheader() const {
+ // Keep track of nodes outside the loop branching to the header...
+ BasicBlock *Out = 0;
+
+ // Loop over the predecessors of the header node...
+ BasicBlock *Header = getHeader();
+ for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
+ PI != PE; ++PI)
+ if (!contains(*PI)) { // If the block is not in the loop...
+ if (Out && Out != *PI)
+ return 0; // Multiple predecessors outside the loop
+ Out = *PI;
+ }
+
+ // If there is exactly one preheader, return it. If there was zero, then Out
+ // is still null.
+ return Out;
+}
+
+/// addBasicBlockToLoop - This function is used by other analyses to update loop
+/// information. NewBB is set to be a new member of the current loop. Because
+/// of this, it is added as a member of all parent loops, and is added to the
+/// specified LoopInfo object as being in the current basic block. It is not
+/// valid to replace the loop header with this method.
+///
+void Loop::addBasicBlockToLoop(BasicBlock *NewBB, LoopInfo &LI) {
+ assert(LI[getHeader()] == this && "Incorrect LI specified for this loop!");
+ assert(NewBB && "Cannot add a null basic block to the loop!");
+ assert(LI[NewBB] == 0 && "BasicBlock already in the loop!");
+
+ // Add the loop mapping to the LoopInfo object...
+ LI.BBMap[NewBB] = this;
+
+ // Add the basic block to this loop and all parent loops...
+ Loop *L = this;
+ while (L) {
+ L->Blocks.push_back(NewBB);
+ L = L->getParentLoop();
+ }
+}
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