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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154385 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2012-04-10 05:14:37 +00:00
parent 0fb0678106
commit 64c0748eb3
1 changed files with 140 additions and 140 deletions
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280
lib/Transforms/Scalar/LoopUnswitch.cpp
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@ -64,63 +64,63 @@ STATISTIC(TotalInsts, "Total number of instructions analyzed");
static cl::opt<unsigned>
Threshold("loop-unswitch-threshold", cl::desc("Max loop size to unswitch"),
cl::init(100), cl::Hidden);
namespace {
class LUAnalysisCache {
typedef DenseMap<const SwitchInst*, SmallPtrSet<const Value *, 8> >
UnswitchedValsMap;
typedef UnswitchedValsMap::iterator UnswitchedValsIt;
struct LoopProperties {
unsigned CanBeUnswitchedCount;
unsigned SizeEstimation;
UnswitchedValsMap UnswitchedVals;
};
// Here we use std::map instead of DenseMap, since we need to keep valid
// Here we use std::map instead of DenseMap, since we need to keep valid
// LoopProperties pointer for current loop for better performance.
typedef std::map<const Loop*, LoopProperties> LoopPropsMap;
typedef LoopPropsMap::iterator LoopPropsMapIt;
LoopPropsMap LoopsProperties;
UnswitchedValsMap* CurLoopInstructions;
LoopProperties* CurrentLoopProperties;
// Max size of code we can produce on remained iterations.
unsigned MaxSize;
public:
LUAnalysisCache() :
CurLoopInstructions(NULL), CurrentLoopProperties(NULL),
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);
// Clean all data related to given loop.
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);
// Check was this case value unswitched before or not.
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);
};
class LoopUnswitch : public LoopPass {
LoopInfo *LI; // Loop information
LPPassManager *LPM;
@ -130,7 +130,7 @@ namespace {
std::vector<Loop*> LoopProcessWorklist;
LUAnalysisCache BranchesInfo;
bool OptimizeForSize;
bool redoLoop;
@ -138,9 +138,9 @@ namespace {
DominatorTree *DT;
BasicBlock *loopHeader;
BasicBlock *loopPreheader;
// LoopBlocks contains all of the basic blocks of the loop, including the
// preheader of the loop, the body of the loop, and the exit blocks of the
// preheader of the loop, the body of the loop, and the exit blocks of the
// loop, in that order.
std::vector<BasicBlock*> LoopBlocks;
// NewBlocks contained cloned copy of basic blocks from LoopBlocks.
@ -148,8 +148,8 @@ namespace {
public:
static char ID; // Pass ID, replacement for typeid
explicit LoopUnswitch(bool Os = false) :
LoopPass(ID), OptimizeForSize(Os), redoLoop(false),
explicit LoopUnswitch(bool Os = false) :
LoopPass(ID), OptimizeForSize(Os), redoLoop(false),
currentLoop(NULL), DT(NULL), loopHeader(NULL),
loopPreheader(NULL) {
initializeLoopUnswitchPass(*PassRegistry::getPassRegistry());
@ -186,14 +186,14 @@ namespace {
if (I != LoopProcessWorklist.end())
LoopProcessWorklist.erase(I);
}
void initLoopData() {
loopHeader = currentLoop->getHeader();
loopPreheader = currentLoop->getLoopPreheader();
}
/// HasIndirectBrsInPreds - Returns true if there are predecessors, that are
/// terminated with indirect branch instruction.
/// terminated with indirect branch instruction.
bool HasIndirectBrsInPreds(const SmallVectorImpl<BasicBlock *> &ExitBlocks);
/// Split all of the edges from inside the loop to their exit blocks.
@ -209,7 +209,7 @@ namespace {
Constant *Val, bool isEqual);
void EmitPreheaderBranchOnCondition(Value *LIC, Constant *Val,
BasicBlock *TrueDest,
BasicBlock *TrueDest,
BasicBlock *FalseDest,
Instruction *InsertPt);
@ -226,12 +226,12 @@ namespace {
// 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) {
std::pair<LoopPropsMapIt, bool> InsertRes =
LoopsProperties.insert(std::make_pair(L, LoopProperties()));
LoopProperties& Props = InsertRes.first->second;
if (InsertRes.second) {
// New loop.
@ -239,39 +239,39 @@ bool LUAnalysisCache::countLoop(const Loop* L) {
// expansion, and the number of basic blocks, to avoid loops with
// large numbers of branches which cause loop unswitching to go crazy.
// This is a very ad-hoc heuristic.
// 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(),
for (Loop::block_iterator I = L->block_begin(),
E = L->block_end();
I != E; ++I)
Metrics.analyzeBasicBlock(*I);
Metrics.analyzeBasicBlock(*I);
Props.SizeEstimation = std::min(Metrics.NumInsts, Metrics.NumBlocks * 5);
Props.CanBeUnswitchedCount = MaxSize / (Props.SizeEstimation);
MaxSize -= Props.SizeEstimation * Props.CanBeUnswitchedCount;
}
}
if (!Props.CanBeUnswitchedCount) {
DEBUG(dbgs() << "NOT unswitching loop %"
<< L->getHeader()->getName() << ", cost too high: "
<< L->getBlocks().size() << "\n");
return false;
}
// Be careful. This links are good only before new loop addition.
CurrentLoopProperties = &Props;
CurLoopInstructions = &Props.UnswitchedVals;
return true;
}
// Clean all data related to given loop.
void LUAnalysisCache::forgetLoop(const Loop* L) {
LoopPropsMapIt LIt = LoopsProperties.find(L);
if (LIt != LoopsProperties.end()) {
@ -279,9 +279,9 @@ void LUAnalysisCache::forgetLoop(const Loop* L) {
MaxSize += Props.CanBeUnswitchedCount * Props.SizeEstimation;
LoopsProperties.erase(LIt);
}
CurrentLoopProperties = NULL;
CurLoopInstructions = NULL;
CurLoopInstructions = NULL;
}
// Mark case value as unswitched.
@ -293,7 +293,7 @@ void LUAnalysisCache::setUnswitched(const SwitchInst* SI, const Value* V) {
// Check was this case value unswitched before or not.
bool LUAnalysisCache::isUnswitched(const SwitchInst* SI, const Value* V) {
return (*CurLoopInstructions)[SI].count(V);
return (*CurLoopInstructions)[SI].count(V);
}
// Clone all loop-unswitch related loop properties.
@ -301,20 +301,20 @@ bool LUAnalysisCache::isUnswitched(const SwitchInst* SI, const Value* V) {
// Note, that new loop data is stored inside the VMap.
void LUAnalysisCache::cloneData(const Loop* NewLoop, const Loop* OldLoop,
const ValueToValueMapTy& VMap) {
LoopProperties& NewLoopProps = LoopsProperties[NewLoop];
LoopProperties& OldLoopProps = *CurrentLoopProperties;
UnswitchedValsMap& Insts = OldLoopProps.UnswitchedVals;
// Reallocate "can-be-unswitched quota"
--OldLoopProps.CanBeUnswitchedCount;
unsigned Quota = OldLoopProps.CanBeUnswitchedCount;
NewLoopProps.CanBeUnswitchedCount = Quota / 2;
OldLoopProps.CanBeUnswitchedCount = Quota - Quota / 2;
NewLoopProps.SizeEstimation = OldLoopProps.SizeEstimation;
// Clone unswitched values info:
// for new loop switches we clone info about values that was
// already unswitched and has redundant successors.
@ -323,7 +323,7 @@ void LUAnalysisCache::cloneData(const Loop* NewLoop, const Loop* OldLoop,
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];
}
}
@ -337,18 +337,18 @@ INITIALIZE_PASS_DEPENDENCY(LCSSA)
INITIALIZE_PASS_END(LoopUnswitch, "loop-unswitch", "Unswitch loops",
false, false)
Pass *llvm::createLoopUnswitchPass(bool Os) {
return new LoopUnswitch(Os);
Pass *llvm::createLoopUnswitchPass(bool Os) {
return new LoopUnswitch(Os);
}
/// FindLIVLoopCondition - Cond is a condition that occurs in L. If it is
/// invariant in the loop, or has an invariant piece, return the invariant.
/// Otherwise, return null.
static Value *FindLIVLoopCondition(Value *Cond, Loop *L, bool &Changed) {
// We started analyze new instruction, increment scanned instructions counter.
++TotalInsts;
// We can never unswitch on vector conditions.
if (Cond->getType()->isVectorTy())
return 0;
@ -373,7 +373,7 @@ static Value *FindLIVLoopCondition(Value *Cond, Loop *L, bool &Changed) {
if (Value *RHS = FindLIVLoopCondition(BO->getOperand(1), L, Changed))
return RHS;
}
return 0;
}
@ -398,19 +398,19 @@ bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) {
return Changed;
}
/// processCurrentLoop - Do actual work and unswitch loop if possible
/// processCurrentLoop - Do actual work and unswitch loop if possible
/// and profitable.
bool LoopUnswitch::processCurrentLoop() {
bool Changed = false;
initLoopData();
// If LoopSimplify was unable to form a preheader, don't do any unswitching.
if (!loopPreheader)
return false;
LLVMContext &Context = loopHeader->getContext();
// Probably we reach the quota of branches for this loop. If so
// stop unswitching.
if (!BranchesInfo.countLoop(currentLoop))
@ -419,7 +419,7 @@ bool LoopUnswitch::processCurrentLoop() {
// Loop over all of the basic blocks in the loop. If we find an interior
// block that is branching on a loop-invariant condition, we can unswitch this
// loop.
for (Loop::block_iterator I = currentLoop->block_begin(),
for (Loop::block_iterator I = currentLoop->block_begin(),
E = currentLoop->block_end(); I != E; ++I) {
TerminatorInst *TI = (*I)->getTerminator();
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
@ -428,24 +428,24 @@ bool LoopUnswitch::processCurrentLoop() {
if (BI->isConditional()) {
// See if this, or some part of it, is loop invariant. If so, we can
// unswitch on it if we desire.
Value *LoopCond = FindLIVLoopCondition(BI->getCondition(),
Value *LoopCond = FindLIVLoopCondition(BI->getCondition(),
currentLoop, Changed);
if (LoopCond && UnswitchIfProfitable(LoopCond,
if (LoopCond && UnswitchIfProfitable(LoopCond,
ConstantInt::getTrue(Context))) {
++NumBranches;
return true;
}
}
}
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
Value *LoopCond = FindLIVLoopCondition(SI->getCondition(),
Value *LoopCond = FindLIVLoopCondition(SI->getCondition(),
currentLoop, Changed);
unsigned NumCases = SI->getNumCases();
unsigned NumCases = SI->getNumCases();
if (LoopCond && NumCases) {
// 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;
// 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.
@ -457,7 +457,7 @@ bool LoopUnswitch::processCurrentLoop() {
break;
}
}
if (!UnswitchVal)
continue;
@ -467,14 +467,14 @@ bool LoopUnswitch::processCurrentLoop() {
}
}
}
// Scan the instructions to check for unswitchable values.
for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
BBI != E; ++BBI)
if (SelectInst *SI = dyn_cast<SelectInst>(BBI)) {
Value *LoopCond = FindLIVLoopCondition(SI->getCondition(),
Value *LoopCond = FindLIVLoopCondition(SI->getCondition(),
currentLoop, Changed);
if (LoopCond && UnswitchIfProfitable(LoopCond,
if (LoopCond && UnswitchIfProfitable(LoopCond,
ConstantInt::getTrue(Context))) {
++NumSelects;
return true;
@ -504,7 +504,7 @@ static bool isTrivialLoopExitBlockHelper(Loop *L, BasicBlock *BB,
ExitBB = BB;
return true;
}
// Otherwise, this is an unvisited intra-loop node. Check all successors.
for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI) {
// Check to see if the successor is a trivial loop exit.
@ -517,12 +517,12 @@ static bool isTrivialLoopExitBlockHelper(Loop *L, BasicBlock *BB,
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
if (I->mayHaveSideEffects())
return false;
return true;
}
/// isTrivialLoopExitBlock - Return true if the specified block unconditionally
/// leads to an exit from the specified loop, and has no side-effects in the
/// leads to an exit from the specified loop, and has no side-effects in the
/// process. If so, return the block that is exited to, otherwise return null.
static BasicBlock *isTrivialLoopExitBlock(Loop *L, BasicBlock *BB) {
std::set<BasicBlock*> Visited;
@ -550,39 +550,39 @@ bool LoopUnswitch::IsTrivialUnswitchCondition(Value *Cond, Constant **Val,
BasicBlock *Header = currentLoop->getHeader();
TerminatorInst *HeaderTerm = Header->getTerminator();
LLVMContext &Context = Header->getContext();
BasicBlock *LoopExitBB = 0;
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.
if (!BI->isConditional() || BI->getCondition() != Cond)
return false;
// Check to see if a successor of the branch is guaranteed to
// exit through a unique exit block without having any
// Check to see if a successor of the branch is guaranteed to
// exit through a unique exit block without having any
// side-effects. If so, determine the value of Cond that causes it to do
// this.
if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop,
if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop,
BI->getSuccessor(0)))) {
if (Val) *Val = ConstantInt::getTrue(Context);
} else if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop,
} else if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop,
BI->getSuccessor(1)))) {
if (Val) *Val = ConstantInt::getFalse(Context);
}
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(HeaderTerm)) {
// If this isn't a switch on Cond, we can't handle it.
if (SI->getCondition() != Cond) return false;
// Check to see if a successor of the switch is guaranteed to go to the
// latch block or exit through a one exit block without having any
// latch block or exit through a one exit block without having any
// side-effects. If so, determine the value of Cond that causes it to do
// this.
// this.
// Note that we can't trivially unswitch on the default case or
// on already unswitched cases.
for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
i != e; ++i) {
BasicBlock* LoopExitCandidate;
if ((LoopExitCandidate = isTrivialLoopExitBlock(currentLoop,
if ((LoopExitCandidate = isTrivialLoopExitBlock(currentLoop,
i.getCaseSuccessor()))) {
// Okay, we found a trivial case, remember the value that is trivial.
ConstantInt* CaseVal = i.getCaseValue();
@ -602,9 +602,9 @@ bool LoopUnswitch::IsTrivialUnswitchCondition(Value *Cond, Constant **Val,
// contains phi nodes, this isn't trivial.
if (!LoopExitBB || isa<PHINode>(LoopExitBB->begin()))
return false; // Can't handle this.
if (LoopExit) *LoopExit = LoopExitBB;
// We already know that nothing uses any scalar values defined inside of this
// loop. As such, we just have to check to see if this loop will execute any
// side-effecting instructions (e.g. stores, calls, volatile loads) in the
@ -689,17 +689,17 @@ void LoopUnswitch::EmitPreheaderBranchOnCondition(Value *LIC, Constant *Val,
/// UnswitchTrivialCondition - Given a loop that has a trivial unswitchable
/// condition in it (a cond branch from its header block to its latch block,
/// where the path through the loop that doesn't execute its body has no
/// where the path through the loop that doesn't execute its body has no
/// side-effects), unswitch it. This doesn't involve any code duplication, just
/// moving the conditional branch outside of the loop and updating loop info.
void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
Constant *Val,
void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
Constant *Val,
BasicBlock *ExitBlock) {
DEBUG(dbgs() << "loop-unswitch: Trivial-Unswitch loop %"
<< loopHeader->getName() << " [" << L->getBlocks().size()
<< " blocks] in Function " << L->getHeader()->getParent()->getName()
<< " on cond: " << *Val << " == " << *Cond << "\n");
// 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.
@ -708,24 +708,24 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
// 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
// short-circuit to.
// Split this block now, so that the loop maintains its exit block, and so
// that the jump from the preheader can execute the contents of the exit block
// 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);
// Okay, now we have a position to branch from and a position to branch to,
// Okay, now we have a position to branch from and a position to branch to,
// insert the new conditional branch.
EmitPreheaderBranchOnCondition(Cond, Val, NewExit, NewPH,
EmitPreheaderBranchOnCondition(Cond, Val, NewExit, NewPH,
loopPreheader->getTerminator());
LPM->deleteSimpleAnalysisValue(loopPreheader->getTerminator(), L);
loopPreheader->getTerminator()->eraseFromParent();
// We need to reprocess this loop, it could be unswitched again.
redoLoop = true;
// Now that we know that the loop is never entered when this condition is a
// particular value, rewrite the loop with this info. We know that this will
// at least eliminate the old branch.
@ -737,7 +737,7 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
/// terminated with indirect branch instruction.
bool LoopUnswitch::HasIndirectBrsInPreds(
const SmallVectorImpl<BasicBlock *> &ExitBlocks){
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
const BasicBlock *ExitBlock = ExitBlocks[i];
for (const_pred_iterator p = pred_begin(ExitBlock), e = pred_end(ExitBlock);
@ -745,7 +745,7 @@ bool LoopUnswitch::HasIndirectBrsInPreds(
// Cannot split an edge from an IndirectBrInst
if (isa<IndirectBrInst>((*p)->getTerminator()))
return true;
}
}
return false;
@ -753,7 +753,7 @@ bool LoopUnswitch::HasIndirectBrsInPreds(
/// SplitExitEdges - Split all of the edges from inside the loop to their exit
/// blocks. Update the appropriate Phi nodes as we do so.
void LoopUnswitch::SplitExitEdges(Loop *L,
void LoopUnswitch::SplitExitEdges(Loop *L,
const SmallVector<BasicBlock *, 8> &ExitBlocks){
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
@ -773,10 +773,10 @@ void LoopUnswitch::SplitExitEdges(Loop *L,
}
}
/// UnswitchNontrivialCondition - We determined that the loop is profitable
/// to unswitch when LIC equal Val. Split it into loop versions and test the
/// UnswitchNontrivialCondition - We determined that the loop is profitable
/// to unswitch when LIC equal Val. Split it into loop versions and test the
/// condition outside of either loop. Return the loops created as Out1/Out2.
bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
Loop *L) {
Function *F = loopHeader->getParent();
DEBUG(dbgs() << "loop-unswitch: Unswitching loop %"
@ -821,7 +821,7 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
ValueToValueMapTy VMap;
for (unsigned i = 0, e = LoopBlocks.size(); i != e; ++i) {
BasicBlock *NewBB = CloneBasicBlock(LoopBlocks[i], VMap, ".us", F);
NewBlocks.push_back(NewBB);
VMap[LoopBlocks[i]] = NewBB; // Keep the BB mapping.
LPM->cloneBasicBlockSimpleAnalysis(LoopBlocks[i], NewBB, L);
@ -851,7 +851,7 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
// 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());
assert(NewExit->getTerminator()->getNumSuccessors() == 1 &&
"Exit block should have been split to have one successor!");
BasicBlock *ExitSucc = NewExit->getTerminator()->getSuccessor(0);
@ -886,7 +886,7 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
for (BasicBlock::iterator I = NewBlocks[i]->begin(),
E = NewBlocks[i]->end(); I != E; ++I)
RemapInstruction(I, VMap,RF_NoModuleLevelChanges|RF_IgnoreMissingEntries);
// Rewrite the original preheader to select between versions of the loop.
BranchInst *OldBR = cast<BranchInst>(loopPreheader->getTerminator());
assert(OldBR->isUnconditional() && OldBR->getSuccessor(0) == LoopBlocks[0] &&
@ -905,7 +905,7 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
// the condition that we're unswitching on), we don't rewrite the second
// iteration.
WeakVH LICHandle(LIC);
// Now we rewrite the original code to know that the condition is true and the
// new code to know that the condition is false.
RewriteLoopBodyWithConditionConstant(L, LIC, Val, false);
@ -916,13 +916,13 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
if (!LoopProcessWorklist.empty() && LoopProcessWorklist.back() == NewLoop &&
LICHandle && !isa<Constant>(LICHandle))
RewriteLoopBodyWithConditionConstant(NewLoop, LICHandle, Val, true);
return true;
}
/// RemoveFromWorklist - Remove all instances of I from the worklist vector
/// specified.
static void RemoveFromWorklist(Instruction *I,
static void RemoveFromWorklist(Instruction *I,
std::vector<Instruction*> &Worklist) {
std::vector<Instruction*>::iterator WI = std::find(Worklist.begin(),
Worklist.end(), I);
@ -935,7 +935,7 @@ static void RemoveFromWorklist(Instruction *I,
/// ReplaceUsesOfWith - When we find that I really equals V, remove I from the
/// program, replacing all uses with V and update the worklist.
static void ReplaceUsesOfWith(Instruction *I, Value *V,
static void ReplaceUsesOfWith(Instruction *I, Value *V,
std::vector<Instruction*> &Worklist,
Loop *L, LPPassManager *LPM) {
DEBUG(dbgs() << "Replace with '" << *V << "': " << *I);
@ -968,10 +968,10 @@ void LoopUnswitch::RemoveBlockIfDead(BasicBlock *BB,
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),
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))
@ -982,15 +982,15 @@ void LoopUnswitch::RemoveBlockIfDead(BasicBlock *BB,
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()))
@ -1001,11 +1001,11 @@ void LoopUnswitch::RemoveBlockIfDead(BasicBlock *BB,
}
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.
@ -1013,7 +1013,7 @@ void LoopUnswitch::RemoveBlockIfDead(BasicBlock *BB,
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)) {
@ -1029,8 +1029,8 @@ void LoopUnswitch::RemoveBlockIfDead(BasicBlock *BB,
// 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;
@ -1038,13 +1038,13 @@ void LoopUnswitch::RemoveBlockIfDead(BasicBlock *BB,
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);
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,
@ -1062,7 +1062,7 @@ void LoopUnswitch::RemoveBlockIfDead(BasicBlock *BB,
--i;
}
}
for (unsigned i = 0, e = Succs.size(); i != e; ++i)
RemoveBlockIfDead(Succs[i], Worklist, L);
}
@ -1085,14 +1085,14 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
Constant *Val,
bool IsEqual) {
assert(!isa<Constant>(LIC) && "Why are we unswitching on a constant?");
// FIXME: Support correlated properties, like:
// for (...)
// if (li1 < li2)
// ...
// if (li1 > li2)
// ...
// FOLD boolean conditions (X|LIC), (X&LIC). Fold conditional branches,
// selects, switches.
std::vector<Instruction*> Worklist;
@ -1107,9 +1107,9 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
if (IsEqual)
Replacement = Val;
else
Replacement = ConstantInt::get(Type::getInt1Ty(Val->getContext()),
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);
@ -1117,15 +1117,15 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
continue;
Worklist.push_back(U);
}
for (std::vector<Instruction*>::iterator UI = Worklist.begin();
UI != Worklist.end(); ++UI)
(*UI)->replaceUsesOfWith(LIC, Replacement);
(*UI)->replaceUsesOfWith(LIC, Replacement);
SimplifyCode(Worklist, L);
return;
}
// 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.
@ -1137,27 +1137,27 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
Worklist.push_back(U);
// TODO: We could do other simplifications, for example, turning
// 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::CaseIt DeadCase = SI->findCaseValue(cast<ConstantInt>(Val));
// Default case is live for multiple values.
if (DeadCase == SI->case_default()) continue;
// Found a dead case value. Don't remove PHI nodes in the
// Found a dead case value. Don't remove PHI nodes in the
// successor if they become single-entry, those PHI nodes may
// be in the Users list.
BasicBlock *Switch = SI->getParent();
BasicBlock *SISucc = DeadCase.getCaseSuccessor();
BasicBlock *Latch = L->getLoopLatch();
BranchesInfo.setUnswitched(SI, Val);
if (!SI->findCaseDest(SISucc)) continue; // Edge is critical.
// If the DeadCase successor dominates the loop latch, then the
// transformation isn't safe since it will delete the sole predecessor edge
@ -1197,7 +1197,7 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
if (DT)
DT->addNewBlock(Abort, NewSISucc);
}
SimplifyCode(Worklist, L);
}
@ -1218,7 +1218,7 @@ void LoopUnswitch::SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L) {
// Simple DCE.
if (isInstructionTriviallyDead(I)) {
DEBUG(dbgs() << "Remove dead instruction '" << *I);
// Add uses to the worklist, which may be dead now.
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
if (Instruction *Use = dyn_cast<Instruction>(I->getOperand(i)))
@ -1250,24 +1250,24 @@ void LoopUnswitch::SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L) {
if (!SinglePred) continue; // Nothing to do.
assert(SinglePred == Pred && "CFG broken");
DEBUG(dbgs() << "Merging blocks: " << Pred->getName() << " <- "
DEBUG(dbgs() << "Merging blocks: " << Pred->getName() << " <- "
<< Succ->getName() << "\n");
// Resolve any single entry PHI nodes in Succ.
while (PHINode *PN = dyn_cast<PHINode>(Succ->begin()))
ReplaceUsesOfWith(PN, PN->getIncomingValue(0), Worklist, L, LPM);
// If Succ has any successors with PHI nodes, update them to have
// entries coming from Pred instead of Succ.
Succ->replaceAllUsesWith(Pred);
// Move all of the successor contents from Succ to Pred.
Pred->getInstList().splice(BI, Succ->getInstList(), Succ->begin(),
Succ->end());
LPM->deleteSimpleAnalysisValue(BI, L);
BI->eraseFromParent();
RemoveFromWorklist(BI, Worklist);
// Remove Succ from the loop tree.
LI->removeBlock(Succ);
LPM->deleteSimpleAnalysisValue(Succ, L);
@ -1275,7 +1275,7 @@ void LoopUnswitch::SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L) {
++NumSimplify;
continue;
}
if (ConstantInt *CB = dyn_cast<ConstantInt>(BI->getCondition())){
// Conditional branch. Turn it into an unconditional branch, then
// remove dead blocks.