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Instead, we're going to separate metadata from the Value hierarchy. See PR21532. This reverts commit r221375. This reverts commit r221373. This reverts commit r221359. This reverts commit r221167. This reverts commit r221027. This reverts commit r221024. This reverts commit r221023. This reverts commit r220995. This reverts commit r220994. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221711 91177308-0d34-0410-b5e6-96231b3b80d8
727 lines
25 KiB
C++
727 lines
25 KiB
C++
//===- LoopInfo.cpp - Natural Loop Calculator -----------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the LoopInfo class that is used to identify natural loops
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// and determine the loop depth of various nodes of the CFG. Note that the
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// loops identified may actually be several natural loops that share the same
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// header node... not just a single natural loop.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/ADT/DepthFirstIterator.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/Analysis/LoopInfoImpl.h"
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#include "llvm/Analysis/LoopIterator.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/IR/CFG.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/Metadata.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include <algorithm>
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using namespace llvm;
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// Explicitly instantiate methods in LoopInfoImpl.h for IR-level Loops.
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template class llvm::LoopBase<BasicBlock, Loop>;
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template class llvm::LoopInfoBase<BasicBlock, Loop>;
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// Always verify loopinfo if expensive checking is enabled.
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#ifdef XDEBUG
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static bool VerifyLoopInfo = true;
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#else
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static bool VerifyLoopInfo = false;
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#endif
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static cl::opt<bool,true>
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VerifyLoopInfoX("verify-loop-info", cl::location(VerifyLoopInfo),
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cl::desc("Verify loop info (time consuming)"));
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char LoopInfo::ID = 0;
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INITIALIZE_PASS_BEGIN(LoopInfo, "loops", "Natural Loop Information", true, true)
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INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
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INITIALIZE_PASS_END(LoopInfo, "loops", "Natural Loop Information", true, true)
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// Loop identifier metadata name.
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static const char *const LoopMDName = "llvm.loop";
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//===----------------------------------------------------------------------===//
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// Loop implementation
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//
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/// isLoopInvariant - Return true if the specified value is loop invariant
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///
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bool Loop::isLoopInvariant(Value *V) const {
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if (Instruction *I = dyn_cast<Instruction>(V))
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return !contains(I);
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return true; // All non-instructions are loop invariant
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}
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/// hasLoopInvariantOperands - Return true if all the operands of the
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/// specified instruction are loop invariant.
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bool Loop::hasLoopInvariantOperands(Instruction *I) const {
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for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
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if (!isLoopInvariant(I->getOperand(i)))
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return false;
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return true;
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}
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/// makeLoopInvariant - If the given value is an instruciton inside of the
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/// loop and it can be hoisted, do so to make it trivially loop-invariant.
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/// Return true if the value after any hoisting is loop invariant. This
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/// function can be used as a slightly more aggressive replacement for
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/// isLoopInvariant.
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///
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/// If InsertPt is specified, it is the point to hoist instructions to.
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/// If null, the terminator of the loop preheader is used.
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///
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bool Loop::makeLoopInvariant(Value *V, bool &Changed,
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Instruction *InsertPt) const {
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if (Instruction *I = dyn_cast<Instruction>(V))
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return makeLoopInvariant(I, Changed, InsertPt);
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return true; // All non-instructions are loop-invariant.
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}
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/// makeLoopInvariant - If the given instruction is inside of the
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/// loop and it can be hoisted, do so to make it trivially loop-invariant.
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/// Return true if the instruction after any hoisting is loop invariant. This
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/// function can be used as a slightly more aggressive replacement for
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/// isLoopInvariant.
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///
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/// If InsertPt is specified, it is the point to hoist instructions to.
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/// If null, the terminator of the loop preheader is used.
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///
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bool Loop::makeLoopInvariant(Instruction *I, bool &Changed,
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Instruction *InsertPt) const {
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// Test if the value is already loop-invariant.
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if (isLoopInvariant(I))
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return true;
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if (!isSafeToSpeculativelyExecute(I))
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return false;
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if (I->mayReadFromMemory())
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return false;
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// The landingpad instruction is immobile.
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if (isa<LandingPadInst>(I))
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return false;
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// Determine the insertion point, unless one was given.
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if (!InsertPt) {
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BasicBlock *Preheader = getLoopPreheader();
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// Without a preheader, hoisting is not feasible.
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if (!Preheader)
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return false;
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InsertPt = Preheader->getTerminator();
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}
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// Don't hoist instructions with loop-variant operands.
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for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
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if (!makeLoopInvariant(I->getOperand(i), Changed, InsertPt))
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return false;
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// Hoist.
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I->moveBefore(InsertPt);
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Changed = true;
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return true;
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}
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/// getCanonicalInductionVariable - Check to see if the loop has a canonical
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/// induction variable: an integer recurrence that starts at 0 and increments
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/// by one each time through the loop. If so, return the phi node that
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/// corresponds to it.
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///
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/// The IndVarSimplify pass transforms loops to have a canonical induction
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/// variable.
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///
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PHINode *Loop::getCanonicalInductionVariable() const {
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BasicBlock *H = getHeader();
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BasicBlock *Incoming = nullptr, *Backedge = nullptr;
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pred_iterator PI = pred_begin(H);
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assert(PI != pred_end(H) &&
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"Loop must have at least one backedge!");
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Backedge = *PI++;
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if (PI == pred_end(H)) return nullptr; // dead loop
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Incoming = *PI++;
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if (PI != pred_end(H)) return nullptr; // multiple backedges?
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if (contains(Incoming)) {
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if (contains(Backedge))
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return nullptr;
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std::swap(Incoming, Backedge);
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} else if (!contains(Backedge))
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return nullptr;
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// Loop over all of the PHI nodes, looking for a canonical indvar.
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for (BasicBlock::iterator I = H->begin(); isa<PHINode>(I); ++I) {
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PHINode *PN = cast<PHINode>(I);
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if (ConstantInt *CI =
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dyn_cast<ConstantInt>(PN->getIncomingValueForBlock(Incoming)))
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if (CI->isNullValue())
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if (Instruction *Inc =
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dyn_cast<Instruction>(PN->getIncomingValueForBlock(Backedge)))
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if (Inc->getOpcode() == Instruction::Add &&
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Inc->getOperand(0) == PN)
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if (ConstantInt *CI = dyn_cast<ConstantInt>(Inc->getOperand(1)))
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if (CI->equalsInt(1))
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return PN;
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}
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return nullptr;
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}
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/// isLCSSAForm - Return true if the Loop is in LCSSA form
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bool Loop::isLCSSAForm(DominatorTree &DT) const {
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for (block_iterator BI = block_begin(), E = block_end(); BI != E; ++BI) {
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BasicBlock *BB = *BI;
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for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;++I)
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for (Use &U : I->uses()) {
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Instruction *UI = cast<Instruction>(U.getUser());
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BasicBlock *UserBB = UI->getParent();
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if (PHINode *P = dyn_cast<PHINode>(UI))
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UserBB = P->getIncomingBlock(U);
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// Check the current block, as a fast-path, before checking whether
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// the use is anywhere in the loop. Most values are used in the same
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// block they are defined in. Also, blocks not reachable from the
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// entry are special; uses in them don't need to go through PHIs.
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if (UserBB != BB &&
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!contains(UserBB) &&
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DT.isReachableFromEntry(UserBB))
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return false;
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}
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}
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return true;
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}
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/// isLoopSimplifyForm - Return true if the Loop is in the form that
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/// the LoopSimplify form transforms loops to, which is sometimes called
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/// normal form.
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bool Loop::isLoopSimplifyForm() const {
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// Normal-form loops have a preheader, a single backedge, and all of their
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// exits have all their predecessors inside the loop.
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return getLoopPreheader() && getLoopLatch() && hasDedicatedExits();
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}
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/// isSafeToClone - Return true if the loop body is safe to clone in practice.
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/// Routines that reform the loop CFG and split edges often fail on indirectbr.
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bool Loop::isSafeToClone() const {
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// Return false if any loop blocks contain indirectbrs, or there are any calls
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// to noduplicate functions.
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for (Loop::block_iterator I = block_begin(), E = block_end(); I != E; ++I) {
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if (isa<IndirectBrInst>((*I)->getTerminator()))
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return false;
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if (const InvokeInst *II = dyn_cast<InvokeInst>((*I)->getTerminator()))
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if (II->cannotDuplicate())
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return false;
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for (BasicBlock::iterator BI = (*I)->begin(), BE = (*I)->end(); BI != BE; ++BI) {
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if (const CallInst *CI = dyn_cast<CallInst>(BI)) {
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if (CI->cannotDuplicate())
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return false;
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}
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}
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}
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return true;
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}
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MDNode *Loop::getLoopID() const {
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MDNode *LoopID = nullptr;
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if (isLoopSimplifyForm()) {
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LoopID = getLoopLatch()->getTerminator()->getMetadata(LoopMDName);
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} else {
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// Go through each predecessor of the loop header and check the
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// terminator for the metadata.
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BasicBlock *H = getHeader();
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for (block_iterator I = block_begin(), IE = block_end(); I != IE; ++I) {
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TerminatorInst *TI = (*I)->getTerminator();
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MDNode *MD = nullptr;
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// Check if this terminator branches to the loop header.
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for (unsigned i = 0, ie = TI->getNumSuccessors(); i != ie; ++i) {
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if (TI->getSuccessor(i) == H) {
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MD = TI->getMetadata(LoopMDName);
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break;
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}
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}
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if (!MD)
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return nullptr;
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if (!LoopID)
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LoopID = MD;
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else if (MD != LoopID)
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return nullptr;
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}
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}
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if (!LoopID || LoopID->getNumOperands() == 0 ||
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LoopID->getOperand(0) != LoopID)
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return nullptr;
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return LoopID;
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}
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void Loop::setLoopID(MDNode *LoopID) const {
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assert(LoopID && "Loop ID should not be null");
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assert(LoopID->getNumOperands() > 0 && "Loop ID needs at least one operand");
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assert(LoopID->getOperand(0) == LoopID && "Loop ID should refer to itself");
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if (isLoopSimplifyForm()) {
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getLoopLatch()->getTerminator()->setMetadata(LoopMDName, LoopID);
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return;
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}
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BasicBlock *H = getHeader();
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for (block_iterator I = block_begin(), IE = block_end(); I != IE; ++I) {
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TerminatorInst *TI = (*I)->getTerminator();
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for (unsigned i = 0, ie = TI->getNumSuccessors(); i != ie; ++i) {
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if (TI->getSuccessor(i) == H)
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TI->setMetadata(LoopMDName, LoopID);
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}
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}
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}
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bool Loop::isAnnotatedParallel() const {
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MDNode *desiredLoopIdMetadata = getLoopID();
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if (!desiredLoopIdMetadata)
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return false;
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// The loop branch contains the parallel loop metadata. In order to ensure
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// that any parallel-loop-unaware optimization pass hasn't added loop-carried
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// dependencies (thus converted the loop back to a sequential loop), check
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// that all the memory instructions in the loop contain parallelism metadata
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// that point to the same unique "loop id metadata" the loop branch does.
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for (block_iterator BB = block_begin(), BE = block_end(); BB != BE; ++BB) {
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for (BasicBlock::iterator II = (*BB)->begin(), EE = (*BB)->end();
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II != EE; II++) {
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if (!II->mayReadOrWriteMemory())
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continue;
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// The memory instruction can refer to the loop identifier metadata
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// directly or indirectly through another list metadata (in case of
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// nested parallel loops). The loop identifier metadata refers to
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// itself so we can check both cases with the same routine.
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MDNode *loopIdMD =
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II->getMetadata(LLVMContext::MD_mem_parallel_loop_access);
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if (!loopIdMD)
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return false;
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bool loopIdMDFound = false;
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for (unsigned i = 0, e = loopIdMD->getNumOperands(); i < e; ++i) {
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if (loopIdMD->getOperand(i) == desiredLoopIdMetadata) {
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loopIdMDFound = true;
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break;
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}
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}
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if (!loopIdMDFound)
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return false;
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}
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}
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return true;
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}
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/// hasDedicatedExits - Return true if no exit block for the loop
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/// has a predecessor that is outside the loop.
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bool Loop::hasDedicatedExits() const {
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// Each predecessor of each exit block of a normal loop is contained
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// within the loop.
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SmallVector<BasicBlock *, 4> ExitBlocks;
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getExitBlocks(ExitBlocks);
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for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
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for (pred_iterator PI = pred_begin(ExitBlocks[i]),
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PE = pred_end(ExitBlocks[i]); PI != PE; ++PI)
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if (!contains(*PI))
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return false;
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// All the requirements are met.
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return true;
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}
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/// getUniqueExitBlocks - Return all unique successor blocks of this loop.
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/// These are the blocks _outside of the current loop_ which are branched to.
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/// This assumes that loop exits are in canonical form.
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///
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void
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Loop::getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const {
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assert(hasDedicatedExits() &&
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"getUniqueExitBlocks assumes the loop has canonical form exits!");
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SmallVector<BasicBlock *, 32> switchExitBlocks;
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for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI) {
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BasicBlock *current = *BI;
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switchExitBlocks.clear();
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for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I) {
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// If block is inside the loop then it is not a exit block.
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if (contains(*I))
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continue;
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pred_iterator PI = pred_begin(*I);
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BasicBlock *firstPred = *PI;
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// If current basic block is this exit block's first predecessor
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// then only insert exit block in to the output ExitBlocks vector.
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// This ensures that same exit block is not inserted twice into
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// ExitBlocks vector.
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if (current != firstPred)
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continue;
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// If a terminator has more then two successors, for example SwitchInst,
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// then it is possible that there are multiple edges from current block
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// to one exit block.
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if (std::distance(succ_begin(current), succ_end(current)) <= 2) {
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ExitBlocks.push_back(*I);
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continue;
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}
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// In case of multiple edges from current block to exit block, collect
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// only one edge in ExitBlocks. Use switchExitBlocks to keep track of
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// duplicate edges.
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if (std::find(switchExitBlocks.begin(), switchExitBlocks.end(), *I)
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== switchExitBlocks.end()) {
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switchExitBlocks.push_back(*I);
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ExitBlocks.push_back(*I);
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}
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}
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}
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}
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/// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one
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/// block, return that block. Otherwise return null.
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BasicBlock *Loop::getUniqueExitBlock() const {
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SmallVector<BasicBlock *, 8> UniqueExitBlocks;
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getUniqueExitBlocks(UniqueExitBlocks);
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if (UniqueExitBlocks.size() == 1)
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return UniqueExitBlocks[0];
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return nullptr;
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}
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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void Loop::dump() const {
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print(dbgs());
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}
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#endif
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//===----------------------------------------------------------------------===//
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// UnloopUpdater implementation
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//
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namespace {
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/// Find the new parent loop for all blocks within the "unloop" whose last
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/// backedges has just been removed.
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class UnloopUpdater {
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Loop *Unloop;
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LoopInfo *LI;
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LoopBlocksDFS DFS;
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// Map unloop's immediate subloops to their nearest reachable parents. Nested
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// loops within these subloops will not change parents. However, an immediate
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// subloop's new parent will be the nearest loop reachable from either its own
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// exits *or* any of its nested loop's exits.
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DenseMap<Loop*, Loop*> SubloopParents;
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// Flag the presence of an irreducible backedge whose destination is a block
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// directly contained by the original unloop.
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bool FoundIB;
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public:
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UnloopUpdater(Loop *UL, LoopInfo *LInfo) :
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Unloop(UL), LI(LInfo), DFS(UL), FoundIB(false) {}
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void updateBlockParents();
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void removeBlocksFromAncestors();
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void updateSubloopParents();
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protected:
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Loop *getNearestLoop(BasicBlock *BB, Loop *BBLoop);
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};
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} // end anonymous namespace
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/// updateBlockParents - Update the parent loop for all blocks that are directly
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/// contained within the original "unloop".
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void UnloopUpdater::updateBlockParents() {
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if (Unloop->getNumBlocks()) {
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// Perform a post order CFG traversal of all blocks within this loop,
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// propagating the nearest loop from sucessors to predecessors.
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LoopBlocksTraversal Traversal(DFS, LI);
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for (LoopBlocksTraversal::POTIterator POI = Traversal.begin(),
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POE = Traversal.end(); POI != POE; ++POI) {
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Loop *L = LI->getLoopFor(*POI);
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Loop *NL = getNearestLoop(*POI, L);
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if (NL != L) {
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// For reducible loops, NL is now an ancestor of Unloop.
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assert((NL != Unloop && (!NL || NL->contains(Unloop))) &&
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"uninitialized successor");
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LI->changeLoopFor(*POI, NL);
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}
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else {
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// Or the current block is part of a subloop, in which case its parent
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// is unchanged.
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assert((FoundIB || Unloop->contains(L)) && "uninitialized successor");
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}
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}
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}
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// Each irreducible loop within the unloop induces a round of iteration using
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// the DFS result cached by Traversal.
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bool Changed = FoundIB;
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for (unsigned NIters = 0; Changed; ++NIters) {
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assert(NIters < Unloop->getNumBlocks() && "runaway iterative algorithm");
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|
|
|
// Iterate over the postorder list of blocks, propagating the nearest loop
|
|
// from successors to predecessors as before.
|
|
Changed = false;
|
|
for (LoopBlocksDFS::POIterator POI = DFS.beginPostorder(),
|
|
POE = DFS.endPostorder(); POI != POE; ++POI) {
|
|
|
|
Loop *L = LI->getLoopFor(*POI);
|
|
Loop *NL = getNearestLoop(*POI, L);
|
|
if (NL != L) {
|
|
assert(NL != Unloop && (!NL || NL->contains(Unloop)) &&
|
|
"uninitialized successor");
|
|
LI->changeLoopFor(*POI, NL);
|
|
Changed = true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// removeBlocksFromAncestors - Remove unloop's blocks from all ancestors below
|
|
/// their new parents.
|
|
void UnloopUpdater::removeBlocksFromAncestors() {
|
|
// Remove all unloop's blocks (including those in nested subloops) from
|
|
// ancestors below the new parent loop.
|
|
for (Loop::block_iterator BI = Unloop->block_begin(),
|
|
BE = Unloop->block_end(); BI != BE; ++BI) {
|
|
Loop *OuterParent = LI->getLoopFor(*BI);
|
|
if (Unloop->contains(OuterParent)) {
|
|
while (OuterParent->getParentLoop() != Unloop)
|
|
OuterParent = OuterParent->getParentLoop();
|
|
OuterParent = SubloopParents[OuterParent];
|
|
}
|
|
// Remove blocks from former Ancestors except Unloop itself which will be
|
|
// deleted.
|
|
for (Loop *OldParent = Unloop->getParentLoop(); OldParent != OuterParent;
|
|
OldParent = OldParent->getParentLoop()) {
|
|
assert(OldParent && "new loop is not an ancestor of the original");
|
|
OldParent->removeBlockFromLoop(*BI);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// updateSubloopParents - Update the parent loop for all subloops directly
|
|
/// nested within unloop.
|
|
void UnloopUpdater::updateSubloopParents() {
|
|
while (!Unloop->empty()) {
|
|
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])
|
|
Parent->addChildLoop(Subloop);
|
|
else
|
|
LI->addTopLevelLoop(Subloop);
|
|
}
|
|
}
|
|
|
|
/// getNearestLoop - Return the nearest parent loop among this block's
|
|
/// successors. If a successor is a subloop header, consider its parent to be
|
|
/// the nearest parent of the subloop's exits.
|
|
///
|
|
/// For subloop blocks, simply update SubloopParents and return NULL.
|
|
Loop *UnloopUpdater::getNearestLoop(BasicBlock *BB, Loop *BBLoop) {
|
|
|
|
// Initially for blocks directly contained by Unloop, NearLoop == Unloop and
|
|
// is considered uninitialized.
|
|
Loop *NearLoop = BBLoop;
|
|
|
|
Loop *Subloop = nullptr;
|
|
if (NearLoop != Unloop && Unloop->contains(NearLoop)) {
|
|
Subloop = NearLoop;
|
|
// Find the subloop ancestor that is directly contained within Unloop.
|
|
while (Subloop->getParentLoop() != Unloop) {
|
|
Subloop = Subloop->getParentLoop();
|
|
assert(Subloop && "subloop is not an ancestor of the original loop");
|
|
}
|
|
// Get the current nearest parent of the Subloop exits, initially Unloop.
|
|
NearLoop =
|
|
SubloopParents.insert(std::make_pair(Subloop, Unloop)).first->second;
|
|
}
|
|
|
|
succ_iterator I = succ_begin(BB), E = succ_end(BB);
|
|
if (I == E) {
|
|
assert(!Subloop && "subloop blocks must have a successor");
|
|
NearLoop = nullptr; // unloop blocks may now exit the function.
|
|
}
|
|
for (; I != E; ++I) {
|
|
if (*I == BB)
|
|
continue; // self loops are uninteresting
|
|
|
|
Loop *L = LI->getLoopFor(*I);
|
|
if (L == Unloop) {
|
|
// This successor has not been processed. This path must lead to an
|
|
// irreducible backedge.
|
|
assert((FoundIB || !DFS.hasPostorder(*I)) && "should have seen IB");
|
|
FoundIB = true;
|
|
}
|
|
if (L != Unloop && Unloop->contains(L)) {
|
|
// Successor is in a subloop.
|
|
if (Subloop)
|
|
continue; // Branching within subloops. Ignore it.
|
|
|
|
// BB branches from the original into a subloop header.
|
|
assert(L->getParentLoop() == Unloop && "cannot skip into nested loops");
|
|
|
|
// Get the current nearest parent of the Subloop's exits.
|
|
L = SubloopParents[L];
|
|
// L could be Unloop if the only exit was an irreducible backedge.
|
|
}
|
|
if (L == Unloop) {
|
|
continue;
|
|
}
|
|
// Handle critical edges from Unloop into a sibling loop.
|
|
if (L && !L->contains(Unloop)) {
|
|
L = L->getParentLoop();
|
|
}
|
|
// Remember the nearest parent loop among successors or subloop exits.
|
|
if (NearLoop == Unloop || !NearLoop || NearLoop->contains(L))
|
|
NearLoop = L;
|
|
}
|
|
if (Subloop) {
|
|
SubloopParents[Subloop] = NearLoop;
|
|
return BBLoop;
|
|
}
|
|
return NearLoop;
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// LoopInfo implementation
|
|
//
|
|
bool LoopInfo::runOnFunction(Function &) {
|
|
releaseMemory();
|
|
LI.Analyze(getAnalysis<DominatorTreeWrapperPass>().getDomTree());
|
|
return false;
|
|
}
|
|
|
|
/// updateUnloop - The last backedge has been removed from a loop--now the
|
|
/// "unloop". Find a new parent for the blocks contained within unloop and
|
|
/// update the loop tree. We don't necessarily have valid dominators at this
|
|
/// point, but LoopInfo is still valid except for the removal of this loop.
|
|
///
|
|
/// Note that Unloop may now be an empty loop. Calling Loop::getHeader without
|
|
/// checking first is illegal.
|
|
void LoopInfo::updateUnloop(Loop *Unloop) {
|
|
|
|
// First handle the special case of no parent loop to simplify the algorithm.
|
|
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) {
|
|
|
|
// Don't reparent blocks in subloops.
|
|
if (getLoopFor(*I) != Unloop)
|
|
continue;
|
|
|
|
// Blocks no longer have a parent but are still referenced by Unloop until
|
|
// the Unloop object is deleted.
|
|
LI.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");
|
|
if (*I == Unloop) {
|
|
LI.removeLoop(I);
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Move all of the subloops to the top-level.
|
|
while (!Unloop->empty())
|
|
LI.addTopLevelLoop(Unloop->removeChildLoop(std::prev(Unloop->end())));
|
|
|
|
return;
|
|
}
|
|
|
|
// Update the parent loop for all blocks within the loop. Blocks within
|
|
// subloops will not change parents.
|
|
UnloopUpdater Updater(Unloop, this);
|
|
Updater.updateBlockParents();
|
|
|
|
// Remove blocks from former ancestor loops.
|
|
Updater.removeBlocksFromAncestors();
|
|
|
|
// Add direct subloops as children in their new parent loop.
|
|
Updater.updateSubloopParents();
|
|
|
|
// Remove unloop from its parent loop.
|
|
Loop *ParentLoop = Unloop->getParentLoop();
|
|
for (Loop::iterator I = ParentLoop->begin();; ++I) {
|
|
assert(I != ParentLoop->end() && "Couldn't find loop");
|
|
if (*I == Unloop) {
|
|
ParentLoop->removeChildLoop(I);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
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.
|
|
|
|
if (!VerifyLoopInfo) return;
|
|
|
|
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);
|
|
}
|
|
|
|
// 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");
|
|
}
|
|
}
|
|
|
|
void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.setPreservesAll();
|
|
AU.addRequired<DominatorTreeWrapperPass>();
|
|
}
|
|
|
|
void LoopInfo::print(raw_ostream &OS, const Module*) const {
|
|
LI.print(OS);
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// LoopBlocksDFS implementation
|
|
//
|
|
|
|
/// Traverse the loop blocks and store the DFS result.
|
|
/// Useful for clients that just want the final DFS result and don't need to
|
|
/// visit blocks during the initial traversal.
|
|
void LoopBlocksDFS::perform(LoopInfo *LI) {
|
|
LoopBlocksTraversal Traversal(*this, LI);
|
|
for (LoopBlocksTraversal::POTIterator POI = Traversal.begin(),
|
|
POE = Traversal.end(); POI != POE; ++POI) ;
|
|
}
|