mirror of
https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206243 91177308-0d34-0410-b5e6-96231b3b80d8
725 lines
25 KiB
C++
725 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/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 = II->getMetadata("llvm.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
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// from successors to predecessors as before.
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Changed = false;
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for (LoopBlocksDFS::POIterator POI = DFS.beginPostorder(),
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POE = DFS.endPostorder(); POI != POE; ++POI) {
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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) ;
|
|
}
|