//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "loop-unswitch"
#include "llvm/Transforms/Scalar.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/CodeMetrics.h"
-#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Module.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <set>
using namespace llvm;
+#define DEBUG_TYPE "loop-unswitch"
+
STATISTIC(NumBranches, "Number of branches unswitched");
STATISTIC(NumSwitches, "Number of switches unswitched");
STATISTIC(NumSelects , "Number of selects unswitched");
typedef LoopPropsMap::iterator LoopPropsMapIt;
LoopPropsMap LoopsProperties;
- UnswitchedValsMap* CurLoopInstructions;
- LoopProperties* CurrentLoopProperties;
+ UnswitchedValsMap *CurLoopInstructions;
+ LoopProperties *CurrentLoopProperties;
// Max size of code we can produce on remained iterations.
unsigned MaxSize;
public:
LUAnalysisCache() :
- CurLoopInstructions(NULL), CurrentLoopProperties(NULL),
+ CurLoopInstructions(nullptr), CurrentLoopProperties(nullptr),
MaxSize(Threshold)
{}
// Analyze loop. Check its size, calculate is it possible to unswitch
// it. Returns true if we can unswitch this loop.
- bool countLoop(const Loop* L, const TargetTransformInfo &TTI);
+ bool countLoop(const Loop *L, const TargetTransformInfo &TTI,
+ AssumptionCache *AC);
// Clean all data related to given loop.
- void forgetLoop(const Loop* L);
+ void forgetLoop(const Loop *L);
// Mark case value as unswitched.
// Since SI instruction can be partly unswitched, in order to avoid
// extra unswitching in cloned loops keep track all unswitched values.
- void setUnswitched(const SwitchInst* SI, const Value* V);
+ void setUnswitched(const SwitchInst *SI, const Value *V);
// Check was this case value unswitched before or not.
- bool isUnswitched(const SwitchInst* SI, const Value* V);
+ bool isUnswitched(const SwitchInst *SI, const Value *V);
// Clone all loop-unswitch related loop properties.
// Redistribute unswitching quotas.
// Note, that new loop data is stored inside the VMap.
- void cloneData(const Loop* NewLoop, const Loop* OldLoop,
- const ValueToValueMapTy& VMap);
+ void cloneData(const Loop *NewLoop, const Loop *OldLoop,
+ const ValueToValueMapTy &VMap);
};
class LoopUnswitch : public LoopPass {
LoopInfo *LI; // Loop information
LPPassManager *LPM;
+ AssumptionCache *AC;
// LoopProcessWorklist - Used to check if second loop needs processing
// after RewriteLoopBodyWithConditionConstant rewrites first loop.
static char ID; // Pass ID, replacement for typeid
explicit LoopUnswitch(bool Os = false) :
LoopPass(ID), OptimizeForSize(Os), redoLoop(false),
- currentLoop(NULL), DT(NULL), loopHeader(NULL),
- loopPreheader(NULL) {
+ currentLoop(nullptr), DT(nullptr), loopHeader(nullptr),
+ loopPreheader(nullptr) {
initializeLoopUnswitchPass(*PassRegistry::getPassRegistry());
}
- bool runOnLoop(Loop *L, LPPassManager &LPM);
+ bool runOnLoop(Loop *L, LPPassManager &LPM) override;
bool processCurrentLoop();
/// This transformation requires natural loop information & requires that
/// loop preheaders be inserted into the CFG.
///
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<AssumptionCacheTracker>();
AU.addRequiredID(LoopSimplifyID);
AU.addPreservedID(LoopSimplifyID);
- AU.addRequired<LoopInfo>();
- AU.addPreserved<LoopInfo>();
+ AU.addRequired<LoopInfoWrapperPass>();
+ AU.addPreserved<LoopInfoWrapperPass>();
AU.addRequiredID(LCSSAID);
AU.addPreservedID(LCSSAID);
- AU.addPreserved<DominatorTree>();
+ AU.addPreserved<DominatorTreeWrapperPass>();
AU.addPreserved<ScalarEvolution>();
- AU.addRequired<TargetTransformInfo>();
+ AU.addRequired<TargetTransformInfoWrapperPass>();
}
private:
- virtual void releaseMemory() {
+ void releaseMemory() override {
BranchesInfo.forgetLoop(currentLoop);
}
- /// RemoveLoopFromWorklist - If the specified loop is on the loop worklist,
- /// remove it.
- void RemoveLoopFromWorklist(Loop *L) {
- std::vector<Loop*>::iterator I = std::find(LoopProcessWorklist.begin(),
- LoopProcessWorklist.end(), L);
- if (I != LoopProcessWorklist.end())
- LoopProcessWorklist.erase(I);
- }
-
void initLoopData() {
loopHeader = currentLoop->getHeader();
loopPreheader = currentLoop->getLoopPreheader();
Instruction *InsertPt);
void SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L);
- void RemoveBlockIfDead(BasicBlock *BB,
- std::vector<Instruction*> &Worklist, Loop *l);
- void RemoveLoopFromHierarchy(Loop *L);
- bool IsTrivialUnswitchCondition(Value *Cond, Constant **Val = 0,
- BasicBlock **LoopExit = 0);
+ bool IsTrivialUnswitchCondition(Value *Cond, Constant **Val = nullptr,
+ BasicBlock **LoopExit = nullptr);
};
}
// Analyze loop. Check its size, calculate is it possible to unswitch
// it. Returns true if we can unswitch this loop.
-bool LUAnalysisCache::countLoop(const Loop *L, const TargetTransformInfo &TTI) {
+bool LUAnalysisCache::countLoop(const Loop *L, const TargetTransformInfo &TTI,
+ AssumptionCache *AC) {
- std::pair<LoopPropsMapIt, bool> InsertRes =
+ LoopPropsMapIt PropsIt;
+ bool Inserted;
+ std::tie(PropsIt, Inserted) =
LoopsProperties.insert(std::make_pair(L, LoopProperties()));
- LoopProperties& Props = InsertRes.first->second;
+ LoopProperties &Props = PropsIt->second;
- if (InsertRes.second) {
+ if (Inserted) {
// New loop.
// Limit the number of instructions to avoid causing significant code
// large numbers of branches which cause loop unswitching to go crazy.
// This is a very ad-hoc heuristic.
+ SmallPtrSet<const Value *, 32> EphValues;
+ CodeMetrics::collectEphemeralValues(L, AC, EphValues);
+
// FIXME: This is overly conservative because it does not take into
// consideration code simplification opportunities and code that can
// be shared by the resultant unswitched loops.
CodeMetrics Metrics;
- for (Loop::block_iterator I = L->block_begin(),
- E = L->block_end();
+ for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
I != E; ++I)
- Metrics.analyzeBasicBlock(*I, TTI);
+ Metrics.analyzeBasicBlock(*I, TTI, EphValues);
Props.SizeEstimation = std::min(Metrics.NumInsts, Metrics.NumBlocks * 5);
Props.CanBeUnswitchedCount = MaxSize / (Props.SizeEstimation);
if (Metrics.notDuplicatable) {
DEBUG(dbgs() << "NOT unswitching loop %"
- << L->getHeader()->getName() << ", contents cannot be "
- << "duplicated!\n");
+ << L->getHeader()->getName() << ", contents cannot be "
+ << "duplicated!\n");
return false;
}
}
if (!Props.CanBeUnswitchedCount) {
DEBUG(dbgs() << "NOT unswitching loop %"
- << L->getHeader()->getName() << ", cost too high: "
- << L->getBlocks().size() << "\n");
-
+ << L->getHeader()->getName() << ", cost too high: "
+ << L->getBlocks().size() << "\n");
return false;
}
}
// Clean all data related to given loop.
-void LUAnalysisCache::forgetLoop(const Loop* L) {
+void LUAnalysisCache::forgetLoop(const Loop *L) {
LoopPropsMapIt LIt = LoopsProperties.find(L);
if (LIt != LoopsProperties.end()) {
- LoopProperties& Props = LIt->second;
+ LoopProperties &Props = LIt->second;
MaxSize += Props.CanBeUnswitchedCount * Props.SizeEstimation;
LoopsProperties.erase(LIt);
}
- CurrentLoopProperties = NULL;
- CurLoopInstructions = NULL;
+ CurrentLoopProperties = nullptr;
+ CurLoopInstructions = nullptr;
}
// Mark case value as unswitched.
// Since SI instruction can be partly unswitched, in order to avoid
// extra unswitching in cloned loops keep track all unswitched values.
-void LUAnalysisCache::setUnswitched(const SwitchInst* SI, const Value* V) {
+void LUAnalysisCache::setUnswitched(const SwitchInst *SI, const Value *V) {
(*CurLoopInstructions)[SI].insert(V);
}
// Check was this case value unswitched before or not.
-bool LUAnalysisCache::isUnswitched(const SwitchInst* SI, const Value* V) {
+bool LUAnalysisCache::isUnswitched(const SwitchInst *SI, const Value *V) {
return (*CurLoopInstructions)[SI].count(V);
}
// Clone all loop-unswitch related loop properties.
// Redistribute unswitching quotas.
// Note, that new loop data is stored inside the VMap.
-void LUAnalysisCache::cloneData(const Loop* NewLoop, const Loop* OldLoop,
- const ValueToValueMapTy& VMap) {
+void LUAnalysisCache::cloneData(const Loop *NewLoop, const Loop *OldLoop,
+ const ValueToValueMapTy &VMap) {
- LoopProperties& NewLoopProps = LoopsProperties[NewLoop];
- LoopProperties& OldLoopProps = *CurrentLoopProperties;
- UnswitchedValsMap& Insts = OldLoopProps.UnswitchedVals;
+ LoopProperties &NewLoopProps = LoopsProperties[NewLoop];
+ LoopProperties &OldLoopProps = *CurrentLoopProperties;
+ UnswitchedValsMap &Insts = OldLoopProps.UnswitchedVals;
// Reallocate "can-be-unswitched quota"
// for new loop switches we clone info about values that was
// already unswitched and has redundant successors.
for (UnswitchedValsIt I = Insts.begin(); I != Insts.end(); ++I) {
- const SwitchInst* OldInst = I->first;
- Value* NewI = VMap.lookup(OldInst);
- const SwitchInst* NewInst = cast_or_null<SwitchInst>(NewI);
+ const SwitchInst *OldInst = I->first;
+ Value *NewI = VMap.lookup(OldInst);
+ const SwitchInst *NewInst = cast_or_null<SwitchInst>(NewI);
assert(NewInst && "All instructions that are in SrcBB must be in VMap.");
NewLoopProps.UnswitchedVals[NewInst] = OldLoopProps.UnswitchedVals[OldInst];
char LoopUnswitch::ID = 0;
INITIALIZE_PASS_BEGIN(LoopUnswitch, "loop-unswitch", "Unswitch loops",
false, false)
-INITIALIZE_AG_DEPENDENCY(TargetTransformInfo)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
-INITIALIZE_PASS_DEPENDENCY(LoopInfo)
+INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LCSSA)
INITIALIZE_PASS_END(LoopUnswitch, "loop-unswitch", "Unswitch loops",
false, false)
// We can never unswitch on vector conditions.
if (Cond->getType()->isVectorTy())
- return 0;
+ return nullptr;
// Constants should be folded, not unswitched on!
- if (isa<Constant>(Cond)) return 0;
+ if (isa<Constant>(Cond)) return nullptr;
// TODO: Handle: br (VARIANT|INVARIANT).
return RHS;
}
- return 0;
+ return nullptr;
}
bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) {
- LI = &getAnalysis<LoopInfo>();
+ if (skipOptnoneFunction(L))
+ return false;
+
+ AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(
+ *L->getHeader()->getParent());
+ LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
LPM = &LPM_Ref;
- DT = getAnalysisIfAvailable<DominatorTree>();
+ DominatorTreeWrapperPass *DTWP =
+ getAnalysisIfAvailable<DominatorTreeWrapperPass>();
+ DT = DTWP ? &DTWP->getDomTree() : nullptr;
currentLoop = L;
Function *F = currentLoop->getHeader()->getParent();
bool Changed = false;
if (Changed) {
// FIXME: Reconstruct dom info, because it is not preserved properly.
if (DT)
- DT->runOnFunction(*F);
+ DT->recalculate(*F);
}
return Changed;
}
// Probably we reach the quota of branches for this loop. If so
// stop unswitching.
- if (!BranchesInfo.countLoop(currentLoop, getAnalysis<TargetTransformInfo>()))
+ if (!BranchesInfo.countLoop(
+ currentLoop, getAnalysis<TargetTransformInfoWrapperPass>().getTTI(
+ *currentLoop->getHeader()->getParent()),
+ AC))
return false;
// Loop over all of the basic blocks in the loop. If we find an interior
// Find a value to unswitch on:
// FIXME: this should chose the most expensive case!
// FIXME: scan for a case with a non-critical edge?
- Constant *UnswitchVal = NULL;
+ Constant *UnswitchVal = nullptr;
// Do not process same value again and again.
// At this point we have some cases already unswitched and
// some not yet unswitched. Let's find the first not yet unswitched one.
for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
i != e; ++i) {
- Constant* UnswitchValCandidate = i.getCaseValue();
+ Constant *UnswitchValCandidate = i.getCaseValue();
if (!BranchesInfo.isUnswitched(SI, UnswitchValCandidate)) {
UnswitchVal = UnswitchValCandidate;
break;
// Already visited. Without more analysis, this could indicate an infinite
// loop.
return false;
- } else if (!L->contains(BB)) {
+ }
+ if (!L->contains(BB)) {
// Otherwise, this is a loop exit, this is fine so long as this is the
// first exit.
- if (ExitBB != 0) return false;
+ if (ExitBB) return false;
ExitBB = BB;
return true;
}
static BasicBlock *isTrivialLoopExitBlock(Loop *L, BasicBlock *BB) {
std::set<BasicBlock*> Visited;
Visited.insert(L->getHeader()); // Branches to header make infinite loops.
- BasicBlock *ExitBB = 0;
+ BasicBlock *ExitBB = nullptr;
if (isTrivialLoopExitBlockHelper(L, BB, ExitBB, Visited))
return ExitBB;
- return 0;
+ return nullptr;
}
/// IsTrivialUnswitchCondition - Check to see if this unswitch condition is
TerminatorInst *HeaderTerm = Header->getTerminator();
LLVMContext &Context = Header->getContext();
- BasicBlock *LoopExitBB = 0;
+ BasicBlock *LoopExitBB = nullptr;
if (BranchInst *BI = dyn_cast<BranchInst>(HeaderTerm)) {
// If the header block doesn't end with a conditional branch on Cond, we
// can't handle it.
// on already unswitched cases.
for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
i != e; ++i) {
- BasicBlock* LoopExitCandidate;
+ BasicBlock *LoopExitCandidate;
if ((LoopExitCandidate = isTrivialLoopExitBlock(currentLoop,
i.getCaseSuccessor()))) {
// Okay, we found a trivial case, remember the value that is trivial.
- ConstantInt* CaseVal = i.getCaseValue();
+ ConstantInt *CaseVal = i.getCaseValue();
// Check that it was not unswitched before, since already unswitched
// trivial vals are looks trivial too.
/// unswitch the loop, reprocess the pieces, then return true.
bool LoopUnswitch::UnswitchIfProfitable(Value *LoopCond, Constant *Val) {
Function *F = loopHeader->getParent();
- Constant *CondVal = 0;
- BasicBlock *ExitBlock = 0;
+ Constant *CondVal = nullptr;
+ BasicBlock *ExitBlock = nullptr;
if (IsTrivialUnswitchCondition(LoopCond, &CondVal, &ExitBlock)) {
// If the condition is trivial, always unswitch. There is no code growth
// Check to see if it would be profitable to unswitch current loop.
// Do not do non-trivial unswitch while optimizing for size.
- if (OptimizeForSize ||
- F->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
- Attribute::OptimizeForSize))
+ if (OptimizeForSize || F->hasFnAttribute(Attribute::OptimizeForSize))
return false;
UnswitchNontrivialCondition(LoopCond, Val, currentLoop);
for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
I != E; ++I)
if (LI->getLoopFor(*I) == L)
- New->addBasicBlockToLoop(cast<BasicBlock>(VM[*I]), LI->getBase());
+ New->addBasicBlockToLoop(cast<BasicBlock>(VM[*I]), *LI);
// Add all of the subloops to the new loop.
for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
// If either edge is critical, split it. This helps preserve LoopSimplify
// form for enclosing loops.
- SplitCriticalEdge(BI, 0, this, false, false, true);
- SplitCriticalEdge(BI, 1, this, false, false, true);
+ auto Options = CriticalEdgeSplittingOptions(DT, LI).setPreserveLCSSA();
+ SplitCriticalEdge(BI, 0, Options);
+ SplitCriticalEdge(BI, 1, Options);
}
/// UnswitchTrivialCondition - Given a loop that has a trivial unswitchable
// First step, split the preheader, so that we know that there is a safe place
// to insert the conditional branch. We will change loopPreheader to have a
// conditional branch on Cond.
- BasicBlock *NewPH = SplitEdge(loopPreheader, loopHeader, this);
+ BasicBlock *NewPH = SplitEdge(loopPreheader, loopHeader, DT, LI);
// Now that we have a place to insert the conditional branch, create a place
// to branch to: this is the exit block out of the loop that we should
// without actually branching to it (the exit block should be dominated by the
// loop header, not the preheader).
assert(!L->contains(ExitBlock) && "Exit block is in the loop?");
- BasicBlock *NewExit = SplitBlock(ExitBlock, ExitBlock->begin(), this);
+ BasicBlock *NewExit = SplitBlock(ExitBlock, ExitBlock->begin(), DT, LI);
// Okay, now we have a position to branch from and a position to branch to,
// insert the new conditional branch.
// Although SplitBlockPredecessors doesn't preserve loop-simplify in
// general, if we call it on all predecessors of all exits then it does.
- if (!ExitBlock->isLandingPad()) {
- SplitBlockPredecessors(ExitBlock, Preds, ".us-lcssa", this);
- } else {
- SmallVector<BasicBlock*, 2> NewBBs;
- SplitLandingPadPredecessors(ExitBlock, Preds, ".us-lcssa", ".us-lcssa",
- this, NewBBs);
- }
+ SplitBlockPredecessors(ExitBlock, Preds, ".us-lcssa",
+ /*AliasAnalysis*/ nullptr, DT, LI,
+ /*PreserveLCSSA*/ true);
}
}
// First step, split the preheader and exit blocks, and add these blocks to
// the LoopBlocks list.
- BasicBlock *NewPreheader = SplitEdge(loopPreheader, loopHeader, this);
+ BasicBlock *NewPreheader = SplitEdge(loopPreheader, loopHeader, DT, LI);
LoopBlocks.push_back(NewPreheader);
// We want the loop to come after the preheader, but before the exit blocks.
F->getBasicBlockList().splice(NewPreheader, F->getBasicBlockList(),
NewBlocks[0], F->end());
+ // FIXME: We could register any cloned assumptions instead of clearing the
+ // whole function's cache.
+ AC->clear();
+
// Now we create the new Loop object for the versioned loop.
Loop *NewLoop = CloneLoop(L, L->getParentLoop(), VMap, LI, LPM);
if (ParentLoop) {
// Make sure to add the cloned preheader and exit blocks to the parent loop
// as well.
- ParentLoop->addBasicBlockToLoop(NewBlocks[0], LI->getBase());
+ ParentLoop->addBasicBlockToLoop(NewBlocks[0], *LI);
}
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
BasicBlock *NewExit = cast<BasicBlock>(VMap[ExitBlocks[i]]);
// The new exit block should be in the same loop as the old one.
if (Loop *ExitBBLoop = LI->getLoopFor(ExitBlocks[i]))
- ExitBBLoop->addBasicBlockToLoop(NewExit, LI->getBase());
+ ExitBBLoop->addBasicBlockToLoop(NewExit, *LI);
assert(NewExit->getTerminator()->getNumSuccessors() == 1 &&
"Exit block should have been split to have one successor!");
// If the successor of the exit block had PHI nodes, add an entry for
// NewExit.
- PHINode *PN;
- for (BasicBlock::iterator I = ExitSucc->begin(); isa<PHINode>(I); ++I) {
- PN = cast<PHINode>(I);
+ for (BasicBlock::iterator I = ExitSucc->begin();
+ PHINode *PN = dyn_cast<PHINode>(I); ++I) {
Value *V = PN->getIncomingValueForBlock(ExitBlocks[i]);
ValueToValueMapTy::iterator It = VMap.find(V);
if (It != VMap.end()) V = It->second;
}
if (LandingPadInst *LPad = NewExit->getLandingPadInst()) {
- PN = PHINode::Create(LPad->getType(), 0, "",
- ExitSucc->getFirstInsertionPt());
+ PHINode *PN = PHINode::Create(LPad->getType(), 0, "",
+ ExitSucc->getFirstInsertionPt());
for (pred_iterator I = pred_begin(ExitSucc), E = pred_end(ExitSucc);
I != E; ++I) {
Worklist.push_back(Use);
// Add users to the worklist which may be simplified now.
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
- UI != E; ++UI)
- Worklist.push_back(cast<Instruction>(*UI));
+ for (User *U : I->users())
+ Worklist.push_back(cast<Instruction>(U));
LPM->deleteSimpleAnalysisValue(I, L);
RemoveFromWorklist(I, Worklist);
I->replaceAllUsesWith(V);
++NumSimplify;
}
-/// RemoveBlockIfDead - If the specified block is dead, remove it, update loop
-/// information, and remove any dead successors it has.
-///
-void LoopUnswitch::RemoveBlockIfDead(BasicBlock *BB,
- std::vector<Instruction*> &Worklist,
- Loop *L) {
- if (pred_begin(BB) != pred_end(BB)) {
- // This block isn't dead, since an edge to BB was just removed, see if there
- // are any easy simplifications we can do now.
- if (BasicBlock *Pred = BB->getSinglePredecessor()) {
- // If it has one pred, fold phi nodes in BB.
- while (isa<PHINode>(BB->begin()))
- ReplaceUsesOfWith(BB->begin(),
- cast<PHINode>(BB->begin())->getIncomingValue(0),
- Worklist, L, LPM);
-
- // If this is the header of a loop and the only pred is the latch, we now
- // have an unreachable loop.
- if (Loop *L = LI->getLoopFor(BB))
- if (loopHeader == BB && L->contains(Pred)) {
- // Remove the branch from the latch to the header block, this makes
- // the header dead, which will make the latch dead (because the header
- // dominates the latch).
- LPM->deleteSimpleAnalysisValue(Pred->getTerminator(), L);
- Pred->getTerminator()->eraseFromParent();
- new UnreachableInst(BB->getContext(), Pred);
-
- // The loop is now broken, remove it from LI.
- RemoveLoopFromHierarchy(L);
-
- // Reprocess the header, which now IS dead.
- RemoveBlockIfDead(BB, Worklist, L);
- return;
- }
-
- // If pred ends in a uncond branch, add uncond branch to worklist so that
- // the two blocks will get merged.
- if (BranchInst *BI = dyn_cast<BranchInst>(Pred->getTerminator()))
- if (BI->isUnconditional())
- Worklist.push_back(BI);
- }
- return;
- }
-
- DEBUG(dbgs() << "Nuking dead block: " << *BB);
-
- // Remove the instructions in the basic block from the worklist.
- for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
- RemoveFromWorklist(I, Worklist);
-
- // Anything that uses the instructions in this basic block should have their
- // uses replaced with undefs.
- // If I is not void type then replaceAllUsesWith undef.
- // This allows ValueHandlers and custom metadata to adjust itself.
- if (!I->getType()->isVoidTy())
- I->replaceAllUsesWith(UndefValue::get(I->getType()));
- }
-
- // If this is the edge to the header block for a loop, remove the loop and
- // promote all subloops.
- if (Loop *BBLoop = LI->getLoopFor(BB)) {
- if (BBLoop->getLoopLatch() == BB) {
- RemoveLoopFromHierarchy(BBLoop);
- if (currentLoop == BBLoop) {
- currentLoop = 0;
- redoLoop = false;
- }
- }
- }
-
- // Remove the block from the loop info, which removes it from any loops it
- // was in.
- LI->removeBlock(BB);
-
-
- // Remove phi node entries in successors for this block.
- TerminatorInst *TI = BB->getTerminator();
- SmallVector<BasicBlock*, 4> Succs;
- for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
- Succs.push_back(TI->getSuccessor(i));
- TI->getSuccessor(i)->removePredecessor(BB);
- }
-
- // Unique the successors, remove anything with multiple uses.
- array_pod_sort(Succs.begin(), Succs.end());
- Succs.erase(std::unique(Succs.begin(), Succs.end()), Succs.end());
-
- // Remove the basic block, including all of the instructions contained in it.
- LPM->deleteSimpleAnalysisValue(BB, L);
- BB->eraseFromParent();
- // Remove successor blocks here that are not dead, so that we know we only
- // have dead blocks in this list. Nondead blocks have a way of becoming dead,
- // then getting removed before we revisit them, which is badness.
- //
- for (unsigned i = 0; i != Succs.size(); ++i)
- if (pred_begin(Succs[i]) != pred_end(Succs[i])) {
- // One exception is loop headers. If this block was the preheader for a
- // loop, then we DO want to visit the loop so the loop gets deleted.
- // We know that if the successor is a loop header, that this loop had to
- // be the preheader: the case where this was the latch block was handled
- // above and headers can only have two predecessors.
- if (!LI->isLoopHeader(Succs[i])) {
- Succs.erase(Succs.begin()+i);
- --i;
- }
- }
-
- for (unsigned i = 0, e = Succs.size(); i != e; ++i)
- RemoveBlockIfDead(Succs[i], Worklist, L);
-}
-
-/// RemoveLoopFromHierarchy - We have discovered that the specified loop has
-/// become unwrapped, either because the backedge was deleted, or because the
-/// edge into the header was removed. If the edge into the header from the
-/// latch block was removed, the loop is unwrapped but subloops are still alive,
-/// so they just reparent loops. If the loops are actually dead, they will be
-/// removed later.
-void LoopUnswitch::RemoveLoopFromHierarchy(Loop *L) {
- LPM->deleteLoopFromQueue(L);
- RemoveLoopFromWorklist(L);
-}
-
// RewriteLoopBodyWithConditionConstant - We know either that the value LIC has
// the value specified by Val in the specified loop, or we know it does NOT have
// that value. Rewrite any uses of LIC or of properties correlated to it.
std::vector<Instruction*> Worklist;
LLVMContext &Context = Val->getContext();
-
// If we know that LIC == Val, or that LIC == NotVal, just replace uses of LIC
// in the loop with the appropriate one directly.
if (IsEqual || (isa<ConstantInt>(Val) &&
Replacement = ConstantInt::get(Type::getInt1Ty(Val->getContext()),
!cast<ConstantInt>(Val)->getZExtValue());
- for (Value::use_iterator UI = LIC->use_begin(), E = LIC->use_end();
- UI != E; ++UI) {
- Instruction *U = dyn_cast<Instruction>(*UI);
- if (!U || !L->contains(U))
+ for (User *U : LIC->users()) {
+ Instruction *UI = dyn_cast<Instruction>(U);
+ if (!UI || !L->contains(UI))
continue;
- Worklist.push_back(U);
+ Worklist.push_back(UI);
}
- for (std::vector<Instruction*>::iterator UI = Worklist.begin();
- UI != Worklist.end(); ++UI)
+ for (std::vector<Instruction*>::iterator UI = Worklist.begin(),
+ UE = Worklist.end(); UI != UE; ++UI)
(*UI)->replaceUsesOfWith(LIC, Replacement);
SimplifyCode(Worklist, L);
// Otherwise, we don't know the precise value of LIC, but we do know that it
// is certainly NOT "Val". As such, simplify any uses in the loop that we
// can. This case occurs when we unswitch switch statements.
- for (Value::use_iterator UI = LIC->use_begin(), E = LIC->use_end();
- UI != E; ++UI) {
- Instruction *U = dyn_cast<Instruction>(*UI);
- if (!U || !L->contains(U))
+ for (User *U : LIC->users()) {
+ Instruction *UI = dyn_cast<Instruction>(U);
+ if (!UI || !L->contains(UI))
continue;
- Worklist.push_back(U);
+ Worklist.push_back(UI);
// TODO: We could do other simplifications, for example, turning
// 'icmp eq LIC, Val' -> false.
// If we know that LIC is not Val, use this info to simplify code.
- SwitchInst *SI = dyn_cast<SwitchInst>(U);
- if (SI == 0 || !isa<ConstantInt>(Val)) continue;
+ SwitchInst *SI = dyn_cast<SwitchInst>(UI);
+ if (!SI || !isa<ConstantInt>(Val)) continue;
SwitchInst::CaseIt DeadCase = SI->findCaseValue(cast<ConstantInt>(Val));
// Default case is live for multiple values.
// and hooked up so as to preserve the loop structure, because
// trying to update it is complicated. So instead we preserve the
// loop structure and put the block on a dead code path.
- SplitEdge(Switch, SISucc, this);
+ SplitEdge(Switch, SISucc, DT, LI);
// Compute the successors instead of relying on the return value
// of SplitEdge, since it may have split the switch successor
// after PHI nodes.
/// pass.
///
void LoopUnswitch::SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L) {
+ const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
while (!Worklist.empty()) {
Instruction *I = Worklist.back();
Worklist.pop_back();
// See if instruction simplification can hack this up. This is common for
// things like "select false, X, Y" after unswitching made the condition be
// 'false'. TODO: update the domtree properly so we can pass it here.
- if (Value *V = SimplifyInstruction(I))
+ if (Value *V = SimplifyInstruction(I, DL))
if (LI->replacementPreservesLCSSAForm(I, V)) {
ReplaceUsesOfWith(I, V, Worklist, L, LPM);
continue;
continue;
}
- if (ConstantInt *CB = dyn_cast<ConstantInt>(BI->getCondition())){
- // Conditional branch. Turn it into an unconditional branch, then
- // remove dead blocks.
- continue; // FIXME: Enable.
-
- DEBUG(dbgs() << "Folded branch: " << *BI);
- BasicBlock *DeadSucc = BI->getSuccessor(CB->getZExtValue());
- BasicBlock *LiveSucc = BI->getSuccessor(!CB->getZExtValue());
- DeadSucc->removePredecessor(BI->getParent(), true);
- Worklist.push_back(BranchInst::Create(LiveSucc, BI));
- LPM->deleteSimpleAnalysisValue(BI, L);
- BI->eraseFromParent();
- RemoveFromWorklist(BI, Worklist);
- ++NumSimplify;
-
- RemoveBlockIfDead(DeadSucc, Worklist, L);
- }
continue;
}
}
projects / oota-llvm.git / blobdiff