//===----------------------------------------------------------------------===//
#include "llvm/Analysis/LoopInfo.h"
-#include "llvm/Constants.h"
-#include "llvm/Instructions.h"
-#include "llvm/Analysis/Dominators.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Analysis/LoopInfoImpl.h"
#include "llvm/Analysis/LoopIterator.h"
#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/Assembly/Writer.h"
-#include "llvm/Support/CFG.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/PassManager.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
-#include "llvm/ADT/DepthFirstIterator.h"
-#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/Support/raw_ostream.h"
#include <algorithm>
using namespace llvm;
VerifyLoopInfoX("verify-loop-info", cl::location(VerifyLoopInfo),
cl::desc("Verify loop info (time consuming)"));
-char LoopInfo::ID = 0;
-INITIALIZE_PASS_BEGIN(LoopInfo, "loops", "Natural Loop Information", true, true)
-INITIALIZE_PASS_DEPENDENCY(DominatorTree)
-INITIALIZE_PASS_END(LoopInfo, "loops", "Natural Loop Information", true, true)
+// Loop identifier metadata name.
+static const char *const LoopMDName = "llvm.loop";
//===----------------------------------------------------------------------===//
// Loop implementation
/// isLoopInvariant - Return true if the specified value is loop invariant
///
-bool Loop::isLoopInvariant(Value *V) const {
- if (Instruction *I = dyn_cast<Instruction>(V))
+bool Loop::isLoopInvariant(const Value *V) const {
+ if (const Instruction *I = dyn_cast<Instruction>(V))
return !contains(I);
return true; // All non-instructions are loop invariant
}
/// hasLoopInvariantOperands - Return true if all the operands of the
/// specified instruction are loop invariant.
-bool Loop::hasLoopInvariantOperands(Instruction *I) const {
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
- if (!isLoopInvariant(I->getOperand(i)))
- return false;
-
- return true;
+bool Loop::hasLoopInvariantOperands(const Instruction *I) const {
+ return all_of(I->operands(), [this](Value *V) { return isLoopInvariant(V); });
}
/// makeLoopInvariant - If the given value is an instruciton inside of the
return false;
if (I->mayReadFromMemory())
return false;
- // The landingpad instruction is immobile.
- if (isa<LandingPadInst>(I))
+ // EH block instructions are immobile.
+ if (I->isEHPad())
return false;
// Determine the insertion point, unless one was given.
if (!InsertPt) {
// Hoist.
I->moveBefore(InsertPt);
+
+ // There is possibility of hoisting this instruction above some arbitrary
+ // condition. Any metadata defined on it can be control dependent on this
+ // condition. Conservatively strip it here so that we don't give any wrong
+ // information to the optimizer.
+ I->dropUnknownNonDebugMetadata();
+
Changed = true;
return true;
}
PHINode *Loop::getCanonicalInductionVariable() const {
BasicBlock *H = getHeader();
- BasicBlock *Incoming = 0, *Backedge = 0;
+ BasicBlock *Incoming = nullptr, *Backedge = nullptr;
pred_iterator PI = pred_begin(H);
assert(PI != pred_end(H) &&
"Loop must have at least one backedge!");
Backedge = *PI++;
- if (PI == pred_end(H)) return 0; // dead loop
+ if (PI == pred_end(H)) return nullptr; // dead loop
Incoming = *PI++;
- if (PI != pred_end(H)) return 0; // multiple backedges?
+ if (PI != pred_end(H)) return nullptr; // multiple backedges?
if (contains(Incoming)) {
if (contains(Backedge))
- return 0;
+ return nullptr;
std::swap(Incoming, Backedge);
} else if (!contains(Backedge))
- return 0;
+ return nullptr;
// Loop over all of the PHI nodes, looking for a canonical indvar.
for (BasicBlock::iterator I = H->begin(); isa<PHINode>(I); ++I) {
if (CI->equalsInt(1))
return PN;
}
- return 0;
+ return nullptr;
}
/// isLCSSAForm - Return true if the Loop is in LCSSA form
bool Loop::isLCSSAForm(DominatorTree &DT) const {
- // Sort the blocks vector so that we can use binary search to do quick
- // lookups.
- SmallPtrSet<BasicBlock*, 16> LoopBBs(block_begin(), block_end());
-
for (block_iterator BI = block_begin(), E = block_end(); BI != E; ++BI) {
BasicBlock *BB = *BI;
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;++I)
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E;
- ++UI) {
- User *U = *UI;
- BasicBlock *UserBB = cast<Instruction>(U)->getParent();
- if (PHINode *P = dyn_cast<PHINode>(U))
- UserBB = P->getIncomingBlock(UI);
+ for (Use &U : I->uses()) {
+ Instruction *UI = cast<Instruction>(U.getUser());
+ BasicBlock *UserBB = UI->getParent();
+ if (PHINode *P = dyn_cast<PHINode>(UI))
+ UserBB = P->getIncomingBlock(U);
// Check the current block, as a fast-path, before checking whether
// the use is anywhere in the loop. Most values are used in the same
// block they are defined in. Also, blocks not reachable from the
// entry are special; uses in them don't need to go through PHIs.
if (UserBB != BB &&
- !LoopBBs.count(UserBB) &&
+ !contains(UserBB) &&
DT.isReachableFromEntry(UserBB))
return false;
}
return true;
}
+bool Loop::isRecursivelyLCSSAForm(DominatorTree &DT) const {
+ if (!isLCSSAForm(DT))
+ return false;
+
+ return std::all_of(begin(), end(), [&](const Loop *L) {
+ return L->isRecursivelyLCSSAForm(DT);
+ });
+}
+
/// isLoopSimplifyForm - Return true if the Loop is in the form that
/// the LoopSimplify form transforms loops to, which is sometimes called
/// normal form.
/// isSafeToClone - Return true if the loop body is safe to clone in practice.
/// Routines that reform the loop CFG and split edges often fail on indirectbr.
bool Loop::isSafeToClone() const {
- // Return false if any loop blocks contain indirectbrs.
+ // Return false if any loop blocks contain indirectbrs, or there are any calls
+ // to noduplicate functions.
for (Loop::block_iterator I = block_begin(), E = block_end(); I != E; ++I) {
if (isa<IndirectBrInst>((*I)->getTerminator()))
return false;
+
+ if (const InvokeInst *II = dyn_cast<InvokeInst>((*I)->getTerminator()))
+ if (II->cannotDuplicate())
+ return false;
+
+ for (BasicBlock::iterator BI = (*I)->begin(), BE = (*I)->end(); BI != BE; ++BI) {
+ if (const CallInst *CI = dyn_cast<CallInst>(BI)) {
+ if (CI->cannotDuplicate())
+ return false;
+ }
+ if (BI->getType()->isTokenTy() && BI->isUsedOutsideOfBlock(*I))
+ return false;
+ }
}
return true;
}
+MDNode *Loop::getLoopID() const {
+ MDNode *LoopID = nullptr;
+ if (isLoopSimplifyForm()) {
+ LoopID = getLoopLatch()->getTerminator()->getMetadata(LoopMDName);
+ } else {
+ // Go through each predecessor of the loop header and check the
+ // terminator for the metadata.
+ BasicBlock *H = getHeader();
+ for (block_iterator I = block_begin(), IE = block_end(); I != IE; ++I) {
+ TerminatorInst *TI = (*I)->getTerminator();
+ MDNode *MD = nullptr;
+
+ // Check if this terminator branches to the loop header.
+ for (unsigned i = 0, ie = TI->getNumSuccessors(); i != ie; ++i) {
+ if (TI->getSuccessor(i) == H) {
+ MD = TI->getMetadata(LoopMDName);
+ break;
+ }
+ }
+ if (!MD)
+ return nullptr;
+
+ if (!LoopID)
+ LoopID = MD;
+ else if (MD != LoopID)
+ return nullptr;
+ }
+ }
+ if (!LoopID || LoopID->getNumOperands() == 0 ||
+ LoopID->getOperand(0) != LoopID)
+ return nullptr;
+ return LoopID;
+}
+
+void Loop::setLoopID(MDNode *LoopID) const {
+ assert(LoopID && "Loop ID should not be null");
+ assert(LoopID->getNumOperands() > 0 && "Loop ID needs at least one operand");
+ assert(LoopID->getOperand(0) == LoopID && "Loop ID should refer to itself");
+
+ if (isLoopSimplifyForm()) {
+ getLoopLatch()->getTerminator()->setMetadata(LoopMDName, LoopID);
+ return;
+ }
+
+ BasicBlock *H = getHeader();
+ for (block_iterator I = block_begin(), IE = block_end(); I != IE; ++I) {
+ TerminatorInst *TI = (*I)->getTerminator();
+ for (unsigned i = 0, ie = TI->getNumSuccessors(); i != ie; ++i) {
+ if (TI->getSuccessor(i) == H)
+ TI->setMetadata(LoopMDName, LoopID);
+ }
+ }
+}
+
+bool Loop::isAnnotatedParallel() const {
+ MDNode *desiredLoopIdMetadata = getLoopID();
+
+ if (!desiredLoopIdMetadata)
+ return false;
+
+ // The loop branch contains the parallel loop metadata. In order to ensure
+ // that any parallel-loop-unaware optimization pass hasn't added loop-carried
+ // dependencies (thus converted the loop back to a sequential loop), check
+ // that all the memory instructions in the loop contain parallelism metadata
+ // that point to the same unique "loop id metadata" the loop branch does.
+ for (block_iterator BB = block_begin(), BE = block_end(); BB != BE; ++BB) {
+ for (BasicBlock::iterator II = (*BB)->begin(), EE = (*BB)->end();
+ II != EE; II++) {
+
+ if (!II->mayReadOrWriteMemory())
+ continue;
+
+ // The memory instruction can refer to the loop identifier metadata
+ // directly or indirectly through another list metadata (in case of
+ // nested parallel loops). The loop identifier metadata refers to
+ // itself so we can check both cases with the same routine.
+ MDNode *loopIdMD =
+ II->getMetadata(LLVMContext::MD_mem_parallel_loop_access);
+
+ if (!loopIdMD)
+ return false;
+
+ bool loopIdMDFound = false;
+ for (unsigned i = 0, e = loopIdMD->getNumOperands(); i < e; ++i) {
+ if (loopIdMD->getOperand(i) == desiredLoopIdMetadata) {
+ loopIdMDFound = true;
+ break;
+ }
+ }
+
+ if (!loopIdMDFound)
+ return false;
+ }
+ }
+ return true;
+}
+
+
/// hasDedicatedExits - Return true if no exit block for the loop
/// has a predecessor that is outside the loop.
bool Loop::hasDedicatedExits() const {
- // Sort the blocks vector so that we can use binary search to do quick
- // lookups.
- SmallPtrSet<BasicBlock *, 16> LoopBBs(block_begin(), block_end());
// Each predecessor of each exit block of a normal loop is contained
// within the loop.
SmallVector<BasicBlock *, 4> ExitBlocks;
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
for (pred_iterator PI = pred_begin(ExitBlocks[i]),
PE = pred_end(ExitBlocks[i]); PI != PE; ++PI)
- if (!LoopBBs.count(*PI))
+ if (!contains(*PI))
return false;
// All the requirements are met.
return true;
assert(hasDedicatedExits() &&
"getUniqueExitBlocks assumes the loop has canonical form exits!");
- // Sort the blocks vector so that we can use binary search to do quick
- // lookups.
- SmallVector<BasicBlock *, 128> LoopBBs(block_begin(), block_end());
- std::sort(LoopBBs.begin(), LoopBBs.end());
-
SmallVector<BasicBlock *, 32> switchExitBlocks;
for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI) {
for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I) {
// If block is inside the loop then it is not a exit block.
- if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
+ if (contains(*I))
continue;
pred_iterator PI = pred_begin(*I);
getUniqueExitBlocks(UniqueExitBlocks);
if (UniqueExitBlocks.size() == 1)
return UniqueExitBlocks[0];
- return 0;
+ return nullptr;
}
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void Loop::dump() const {
print(dbgs());
}
+#endif
//===----------------------------------------------------------------------===//
// UnloopUpdater implementation
/// nested within unloop.
void UnloopUpdater::updateSubloopParents() {
while (!Unloop->empty()) {
- Loop *Subloop = *llvm::prior(Unloop->end());
- Unloop->removeChildLoop(llvm::prior(Unloop->end()));
+ Loop *Subloop = *std::prev(Unloop->end());
+ Unloop->removeChildLoop(std::prev(Unloop->end()));
assert(SubloopParents.count(Subloop) && "DFS failed to visit subloop");
if (Loop *Parent = SubloopParents[Subloop])
// is considered uninitialized.
Loop *NearLoop = BBLoop;
- Loop *Subloop = 0;
+ Loop *Subloop = nullptr;
if (NearLoop != Unloop && Unloop->contains(NearLoop)) {
Subloop = NearLoop;
// Find the subloop ancestor that is directly contained within Unloop.
succ_iterator I = succ_begin(BB), E = succ_end(BB);
if (I == E) {
assert(!Subloop && "subloop blocks must have a successor");
- NearLoop = 0; // unloop blocks may now exit the function.
+ NearLoop = nullptr; // unloop blocks may now exit the function.
}
for (; I != E; ++I) {
if (*I == BB)
return NearLoop;
}
-//===----------------------------------------------------------------------===//
-// LoopInfo implementation
-//
-bool LoopInfo::runOnFunction(Function &) {
- releaseMemory();
- LI.Analyze(getAnalysis<DominatorTree>().getBase());
- return false;
+LoopInfo::LoopInfo(const DominatorTreeBase<BasicBlock> &DomTree) {
+ analyze(DomTree);
}
/// updateUnloop - The last backedge has been removed from a loop--now the
if (!Unloop->getParentLoop()) {
// Since BBLoop had no parent, Unloop blocks are no longer in a loop.
for (Loop::block_iterator I = Unloop->block_begin(),
- E = Unloop->block_end(); I != E; ++I) {
+ E = Unloop->block_end();
+ I != E; ++I) {
// Don't reparent blocks in subloops.
if (getLoopFor(*I) != Unloop)
// Blocks no longer have a parent but are still referenced by Unloop until
// the Unloop object is deleted.
- LI.changeLoopFor(*I, 0);
+ changeLoopFor(*I, nullptr);
}
// Remove the loop from the top-level LoopInfo object.
- for (LoopInfo::iterator I = LI.begin();; ++I) {
- assert(I != LI.end() && "Couldn't find loop");
+ for (iterator I = begin();; ++I) {
+ assert(I != end() && "Couldn't find loop");
if (*I == Unloop) {
- LI.removeLoop(I);
+ removeLoop(I);
break;
}
}
// Move all of the subloops to the top-level.
while (!Unloop->empty())
- LI.addTopLevelLoop(Unloop->removeChildLoop(llvm::prior(Unloop->end())));
+ addTopLevelLoop(Unloop->removeChildLoop(std::prev(Unloop->end())));
return;
}
}
}
-void LoopInfo::verifyAnalysis() const {
- // LoopInfo is a FunctionPass, but verifying every loop in the function
- // each time verifyAnalysis is called is very expensive. The
- // -verify-loop-info option can enable this. In order to perform some
- // checking by default, LoopPass has been taught to call verifyLoop
- // manually during loop pass sequences.
+char LoopAnalysis::PassID;
+
+LoopInfo LoopAnalysis::run(Function &F, AnalysisManager<Function> *AM) {
+ // FIXME: Currently we create a LoopInfo from scratch for every function.
+ // This may prove to be too wasteful due to deallocating and re-allocating
+ // memory each time for the underlying map and vector datastructures. At some
+ // point it may prove worthwhile to use a freelist and recycle LoopInfo
+ // objects. I don't want to add that kind of complexity until the scope of
+ // the problem is better understood.
+ LoopInfo LI;
+ LI.analyze(AM->getResult<DominatorTreeAnalysis>(F));
+ return LI;
+}
+
+PreservedAnalyses LoopPrinterPass::run(Function &F,
+ AnalysisManager<Function> *AM) {
+ AM->getResult<LoopAnalysis>(F).print(OS);
+ return PreservedAnalyses::all();
+}
- if (!VerifyLoopInfo) return;
+PrintLoopPass::PrintLoopPass() : OS(dbgs()) {}
+PrintLoopPass::PrintLoopPass(raw_ostream &OS, const std::string &Banner)
+ : OS(OS), Banner(Banner) {}
- DenseSet<const Loop*> Loops;
- for (iterator I = begin(), E = end(); I != E; ++I) {
- assert(!(*I)->getParentLoop() && "Top-level loop has a parent!");
- (*I)->verifyLoopNest(&Loops);
- }
+PreservedAnalyses PrintLoopPass::run(Loop &L) {
+ OS << Banner;
+ for (auto *Block : L.blocks())
+ if (Block)
+ Block->print(OS);
+ else
+ OS << "Printing <null> block";
+ return PreservedAnalyses::all();
+}
- // Verify that blocks are mapped to valid loops.
- for (DenseMap<BasicBlock*, Loop*>::const_iterator I = LI.BBMap.begin(),
- E = LI.BBMap.end(); I != E; ++I) {
- assert(Loops.count(I->second) && "orphaned loop");
- assert(I->second->contains(I->first) && "orphaned block");
- }
+//===----------------------------------------------------------------------===//
+// LoopInfo implementation
+//
+
+char LoopInfoWrapperPass::ID = 0;
+INITIALIZE_PASS_BEGIN(LoopInfoWrapperPass, "loops", "Natural Loop Information",
+ true, true)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_END(LoopInfoWrapperPass, "loops", "Natural Loop Information",
+ true, true)
+
+bool LoopInfoWrapperPass::runOnFunction(Function &) {
+ releaseMemory();
+ LI.analyze(getAnalysis<DominatorTreeWrapperPass>().getDomTree());
+ return false;
+}
+
+void LoopInfoWrapperPass::verifyAnalysis() const {
+ // LoopInfoWrapperPass is a FunctionPass, but verifying every loop in the
+ // function each time verifyAnalysis is called is very expensive. The
+ // -verify-loop-info option can enable this. In order to perform some
+ // checking by default, LoopPass has been taught to call verifyLoop manually
+ // during loop pass sequences.
+ if (VerifyLoopInfo)
+ LI.verify();
}
-void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
+void LoopInfoWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
- AU.addRequired<DominatorTree>();
+ AU.addRequired<DominatorTreeWrapperPass>();
}
-void LoopInfo::print(raw_ostream &OS, const Module*) const {
+void LoopInfoWrapperPass::print(raw_ostream &OS, const Module *) const {
LI.print(OS);
}
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