void detail::PtrUseVisitorBase::enqueueUsers(Instruction &I) {
for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
UI != UE; ++UI) {
if (VisitedUses.insert(&UI.getUse())) {
UseToVisit NewU = {
UseToVisit::UseAndIsOffsetKnownPair(&UI.getUse(), IsOffsetKnown),
Offset
};
Worklist.push_back(llvm_move(NewU));
}
}
}
void BBCloner::UpdateSSA(Function &F) {
DominatorTree &DT = getAnalysis<DominatorTree>();
// The function has been greatly modified since the beginning.
DT.runOnFunction(F);
vector<pair<Instruction *, Use *> > ToResolve;
for (ValueToValueMapTy::iterator I = CloneMap.begin();
I != CloneMap.end();
++I) {
Value *Key = const_cast<Value *>(I->first);
if (Instruction *OldIns = dyn_cast<Instruction>(Key)) {
for (Value::use_iterator UI = OldIns->use_begin();
UI != OldIns->use_end();
++UI) {
if (Instruction *User = dyn_cast<Instruction>(*UI)) {
if (!DT.dominates(OldIns, User))
ToResolve.push_back(make_pair(OldIns, &UI.getUse()));
}
}
Instruction *NewIns = cast<Instruction>(I->second);
for (Value::use_iterator UI = NewIns->use_begin();
UI != NewIns->use_end();
++UI) {
if (Instruction *User = dyn_cast<Instruction>(*UI)) {
if (!DT.dominates(NewIns, User)) {
// Use OldIns intentionally.
ToResolve.push_back(make_pair(OldIns, &UI.getUse()));
}
}
}
}
}
for (size_t i = 0; i < ToResolve.size(); ) {
Instruction *OldIns = ToResolve[i].first;
Instruction *NewIns = cast<Instruction>(CloneMap.lookup(OldIns));
SSAUpdater SU;
SU.Initialize(OldIns->getType(), OldIns->getName());
SU.AddAvailableValue(OldIns->getParent(), OldIns);
SU.AddAvailableValue(NewIns->getParent(), NewIns);
size_t j = i;
while (j < ToResolve.size() && ToResolve[j].first == ToResolve[i].first) {
SU.RewriteUse(*ToResolve[j].second);
++j;
}
i = j;
}
}
/// RewriteUsesOfClonedInstructions - We just cloned the instructions from the
/// old header into the preheader. If there were uses of the values produced by
/// these instruction that were outside of the loop, we have to insert PHI nodes
/// to merge the two values. Do this now.
static void RewriteUsesOfClonedInstructions(BasicBlock *OrigHeader,
BasicBlock *OrigPreheader,
ValueToValueMapTy &ValueMap) {
// Remove PHI node entries that are no longer live.
BasicBlock::iterator I, E = OrigHeader->end();
for (I = OrigHeader->begin(); PHINode *PN = dyn_cast<PHINode>(I); ++I)
PN->removeIncomingValue(PN->getBasicBlockIndex(OrigPreheader));
// Now fix up users of the instructions in OrigHeader, inserting PHI nodes
// as necessary.
SSAUpdater SSA;
for (I = OrigHeader->begin(); I != E; ++I) {
Value *OrigHeaderVal = I;
// If there are no uses of the value (e.g. because it returns void), there
// is nothing to rewrite.
if (OrigHeaderVal->use_empty())
continue;
Value *OrigPreHeaderVal = ValueMap[OrigHeaderVal];
// The value now exits in two versions: the initial value in the preheader
// and the loop "next" value in the original header.
SSA.Initialize(OrigHeaderVal->getType(), OrigHeaderVal->getName());
SSA.AddAvailableValue(OrigHeader, OrigHeaderVal);
SSA.AddAvailableValue(OrigPreheader, OrigPreHeaderVal);
// Visit each use of the OrigHeader instruction.
for (Value::use_iterator UI = OrigHeaderVal->use_begin(),
UE = OrigHeaderVal->use_end(); UI != UE; ) {
// Grab the use before incrementing the iterator.
Use &U = UI.getUse();
// Increment the iterator before removing the use from the list.
++UI;
// SSAUpdater can't handle a non-PHI use in the same block as an
// earlier def. We can easily handle those cases manually.
Instruction *UserInst = cast<Instruction>(U.getUser());
if (!isa<PHINode>(UserInst)) {
BasicBlock *UserBB = UserInst->getParent();
// The original users in the OrigHeader are already using the
// original definitions.
if (UserBB == OrigHeader)
continue;
// Users in the OrigPreHeader need to use the value to which the
// original definitions are mapped.
if (UserBB == OrigPreheader) {
U = OrigPreHeaderVal;
continue;
}
}
// Anything else can be handled by SSAUpdater.
SSA.RewriteUse(U);
}
}
}
/// WriteThunk - Replace G with a simple tail call to bitcast(F). Also replace
/// direct uses of G with bitcast(F). Deletes G.
void MergeFunctions::WriteThunk(Function *F, Function *G) const {
if (!G->mayBeOverridden()) {
// Redirect direct callers of G to F.
Constant *BitcastF = ConstantExpr::getBitCast(F, G->getType());
for (Value::use_iterator UI = G->use_begin(), UE = G->use_end();
UI != UE;) {
Value::use_iterator TheIter = UI;
++UI;
CallSite CS(*TheIter);
if (CS && CS.isCallee(TheIter))
TheIter.getUse().set(BitcastF);
}
}
// If G was internal then we may have replaced all uses of G with F. If so,
// stop here and delete G. There's no need for a thunk.
if (G->hasLocalLinkage() && G->use_empty()) {
G->eraseFromParent();
return;
}
Function *NewG = Function::Create(G->getFunctionType(), G->getLinkage(), "",
G->getParent());
BasicBlock *BB = BasicBlock::Create(F->getContext(), "", NewG);
IRBuilder<false> Builder(BB);
SmallVector<Value *, 16> Args;
unsigned i = 0;
const FunctionType *FFTy = F->getFunctionType();
for (Function::arg_iterator AI = NewG->arg_begin(), AE = NewG->arg_end();
AI != AE; ++AI) {
Args.push_back(Builder.CreateBitCast(AI, FFTy->getParamType(i)));
++i;
}
CallInst *CI = Builder.CreateCall(F, Args.begin(), Args.end());
CI->setTailCall();
CI->setCallingConv(F->getCallingConv());
if (NewG->getReturnType()->isVoidTy()) {
Builder.CreateRetVoid();
} else {
Builder.CreateRet(Builder.CreateBitCast(CI, NewG->getReturnType()));
}
NewG->copyAttributesFrom(G);
NewG->takeName(G);
G->replaceAllUsesWith(NewG);
G->eraseFromParent();
DEBUG(dbgs() << "WriteThunk: " << NewG->getName() << '\n');
++NumThunksWritten;
}
// Replace direct callers of Old with New.
void MergeFunctions::replaceDirectCallers(Function *Old, Function *New) {
Constant *BitcastNew = ConstantExpr::getBitCast(New, Old->getType());
for (Value::use_iterator UI = Old->use_begin(), UE = Old->use_end();
UI != UE;) {
Value::use_iterator TheIter = UI;
++UI;
CallSite CS(*TheIter);
if (CS && CS.isCallee(TheIter)) {
remove(CS.getInstruction()->getParent()->getParent());
TheIter.getUse().set(BitcastNew);
}
}
}
/// OptimizeCmpExpression - sink the given CmpInst into user blocks to reduce
/// the number of virtual registers that must be created and coalesced. This is
/// a clear win except on targets with multiple condition code registers
/// (PowerPC), where it might lose; some adjustment may be wanted there.
///
/// Return true if any changes are made.
static bool OptimizeCmpExpression(CmpInst *CI) {
BasicBlock *DefBB = CI->getParent();
/// InsertedCmp - Only insert a cmp in each block once.
DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
bool MadeChange = false;
for (Value::use_iterator UI = CI->use_begin(), E = CI->use_end();
UI != E; ) {
Use &TheUse = UI.getUse();
Instruction *User = cast<Instruction>(*UI);
// Preincrement use iterator so we don't invalidate it.
++UI;
// Don't bother for PHI nodes.
if (isa<PHINode>(User))
continue;
// Figure out which BB this cmp is used in.
BasicBlock *UserBB = User->getParent();
// If this user is in the same block as the cmp, don't change the cmp.
if (UserBB == DefBB) continue;
// If we have already inserted a cmp into this block, use it.
CmpInst *&InsertedCmp = InsertedCmps[UserBB];
if (!InsertedCmp) {
BasicBlock::iterator InsertPt = UserBB->getFirstNonPHI();
InsertedCmp =
CmpInst::Create(CI->getOpcode(),
CI->getPredicate(), CI->getOperand(0),
CI->getOperand(1), "", InsertPt);
MadeChange = true;
}
// Replace a use of the cmp with a use of the new cmp.
TheUse = InsertedCmp;
++NumCmpUses;
}
// If we removed all uses, nuke the cmp.
if (CI->use_empty())
CI->eraseFromParent();
return MadeChange;
}
// For each instruction used by the value, remove() the function that contains
// the instruction. This should happen right before a call to RAUW.
void MergeFunctions::removeUsers(Value *V) {
std::vector<Value *> Worklist;
Worklist.push_back(V);
while (!Worklist.empty()) {
Value *V = Worklist.back();
Worklist.pop_back();
for (Value::use_iterator UI = V->use_begin(), UE = V->use_end();
UI != UE; ++UI) {
Use &U = UI.getUse();
if (Instruction *I = dyn_cast<Instruction>(U.getUser())) {
remove(I->getParent()->getParent());
} else if (isa<GlobalValue>(U.getUser())) {
// do nothing
} else if (Constant *C = dyn_cast<Constant>(U.getUser())) {
for (Value::use_iterator CUI = C->use_begin(), CUE = C->use_end();
CUI != CUE; ++CUI)
Worklist.push_back(*CUI);
}
}
}
}
/// OptimizeNoopCopyExpression - If the specified cast instruction is a noop
/// copy (e.g. it's casting from one pointer type to another, i32->i8 on PPC),
/// sink it into user blocks to reduce the number of virtual
/// registers that must be created and coalesced.
///
/// Return true if any changes are made.
///
static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI) {
// If this is a noop copy,
EVT SrcVT = TLI.getValueType(CI->getOperand(0)->getType());
EVT DstVT = TLI.getValueType(CI->getType());
// This is an fp<->int conversion?
if (SrcVT.isInteger() != DstVT.isInteger())
return false;
// If this is an extension, it will be a zero or sign extension, which
// isn't a noop.
if (SrcVT.bitsLT(DstVT)) return false;
// If these values will be promoted, find out what they will be promoted
// to. This helps us consider truncates on PPC as noop copies when they
// are.
if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
TargetLowering::TypePromoteInteger)
SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
if (TLI.getTypeAction(CI->getContext(), DstVT) ==
TargetLowering::TypePromoteInteger)
DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
// If, after promotion, these are the same types, this is a noop copy.
if (SrcVT != DstVT)
return false;
BasicBlock *DefBB = CI->getParent();
/// InsertedCasts - Only insert a cast in each block once.
DenseMap<BasicBlock*, CastInst*> InsertedCasts;
bool MadeChange = false;
for (Value::use_iterator UI = CI->use_begin(), E = CI->use_end();
UI != E; ) {
Use &TheUse = UI.getUse();
Instruction *User = cast<Instruction>(*UI);
// Figure out which BB this cast is used in. For PHI's this is the
// appropriate predecessor block.
BasicBlock *UserBB = User->getParent();
if (PHINode *PN = dyn_cast<PHINode>(User)) {
UserBB = PN->getIncomingBlock(UI);
}
// Preincrement use iterator so we don't invalidate it.
++UI;
// If this user is in the same block as the cast, don't change the cast.
if (UserBB == DefBB) continue;
// If we have already inserted a cast into this block, use it.
CastInst *&InsertedCast = InsertedCasts[UserBB];
if (!InsertedCast) {
BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
InsertedCast =
CastInst::Create(CI->getOpcode(), CI->getOperand(0), CI->getType(), "",
InsertPt);
MadeChange = true;
}
// Replace a use of the cast with a use of the new cast.
TheUse = InsertedCast;
++NumCastUses;
}
// If we removed all uses, nuke the cast.
if (CI->use_empty()) {
CI->eraseFromParent();
MadeChange = true;
}
return MadeChange;
}
bool CodeGenPrepare::OptimizeExtUses(Instruction *I) {
BasicBlock *DefBB = I->getParent();
// If the result of a {s|z}ext and its source are both live out, rewrite all
// other uses of the source with result of extension.
Value *Src = I->getOperand(0);
if (Src->hasOneUse())
return false;
// Only do this xform if truncating is free.
if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
return false;
// Only safe to perform the optimization if the source is also defined in
// this block.
if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
return false;
bool DefIsLiveOut = false;
for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
UI != E; ++UI) {
Instruction *User = cast<Instruction>(*UI);
// Figure out which BB this ext is used in.
BasicBlock *UserBB = User->getParent();
if (UserBB == DefBB) continue;
DefIsLiveOut = true;
break;
}
if (!DefIsLiveOut)
return false;
// Make sure non of the uses are PHI nodes.
for (Value::use_iterator UI = Src->use_begin(), E = Src->use_end();
UI != E; ++UI) {
Instruction *User = cast<Instruction>(*UI);
BasicBlock *UserBB = User->getParent();
if (UserBB == DefBB) continue;
// Be conservative. We don't want this xform to end up introducing
// reloads just before load / store instructions.
if (isa<PHINode>(User) || isa<LoadInst>(User) || isa<StoreInst>(User))
return false;
}
// InsertedTruncs - Only insert one trunc in each block once.
DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
bool MadeChange = false;
for (Value::use_iterator UI = Src->use_begin(), E = Src->use_end();
UI != E; ++UI) {
Use &TheUse = UI.getUse();
Instruction *User = cast<Instruction>(*UI);
// Figure out which BB this ext is used in.
BasicBlock *UserBB = User->getParent();
if (UserBB == DefBB) continue;
// Both src and def are live in this block. Rewrite the use.
Instruction *&InsertedTrunc = InsertedTruncs[UserBB];
if (!InsertedTrunc) {
BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
InsertedTrunc = new TruncInst(I, Src->getType(), "", InsertPt);
}
// Replace a use of the {s|z}ext source with a use of the result.
TheUse = InsertedTrunc;
++NumExtUses;
MadeChange = true;
}
return MadeChange;
}
/// sink - When an instruction is found to only be used outside of the loop,
/// this function moves it to the exit blocks and patches up SSA form as needed.
/// This method is guaranteed to remove the original instruction from its
/// position, and may either delete it or move it to outside of the loop.
///
void LICM::sink(Instruction &I) {
DEBUG(dbgs() << "LICM sinking instruction: " << I << "\n");
SmallVector<BasicBlock*, 8> ExitBlocks;
CurLoop->getUniqueExitBlocks(ExitBlocks);
if (isa<LoadInst>(I)) ++NumMovedLoads;
else if (isa<CallInst>(I)) ++NumMovedCalls;
++NumSunk;
Changed = true;
// The case where there is only a single exit node of this loop is common
// enough that we handle it as a special (more efficient) case. It is more
// efficient to handle because there are no PHI nodes that need to be placed.
if (ExitBlocks.size() == 1) {
if (!DT->dominates(I.getParent(), ExitBlocks[0])) {
// Instruction is not used, just delete it.
CurAST->deleteValue(&I);
// If I has users in unreachable blocks, eliminate.
// If I is not void type then replaceAllUsesWith undef.
// This allows ValueHandlers and custom metadata to adjust itself.
if (!I.use_empty())
I.replaceAllUsesWith(UndefValue::get(I.getType()));
I.eraseFromParent();
} else {
// Move the instruction to the start of the exit block, after any PHI
// nodes in it.
I.moveBefore(ExitBlocks[0]->getFirstInsertionPt());
// This instruction is no longer in the AST for the current loop, because
// we just sunk it out of the loop. If we just sunk it into an outer
// loop, we will rediscover the operation when we process it.
CurAST->deleteValue(&I);
}
return;
}
if (ExitBlocks.empty()) {
// The instruction is actually dead if there ARE NO exit blocks.
CurAST->deleteValue(&I);
// If I has users in unreachable blocks, eliminate.
// If I is not void type then replaceAllUsesWith undef.
// This allows ValueHandlers and custom metadata to adjust itself.
if (!I.use_empty())
I.replaceAllUsesWith(UndefValue::get(I.getType()));
I.eraseFromParent();
return;
}
// Otherwise, if we have multiple exits, use the SSAUpdater to do all of the
// hard work of inserting PHI nodes as necessary.
SmallVector<PHINode*, 8> NewPHIs;
SSAUpdater SSA(&NewPHIs);
if (!I.use_empty())
SSA.Initialize(I.getType(), I.getName());
// Insert a copy of the instruction in each exit block of the loop that is
// dominated by the instruction. Each exit block is known to only be in the
// ExitBlocks list once.
BasicBlock *InstOrigBB = I.getParent();
unsigned NumInserted = 0;
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
BasicBlock *ExitBlock = ExitBlocks[i];
if (!DT->dominates(InstOrigBB, ExitBlock))
continue;
// Insert the code after the last PHI node.
BasicBlock::iterator InsertPt = ExitBlock->getFirstInsertionPt();
// If this is the first exit block processed, just move the original
// instruction, otherwise clone the original instruction and insert
// the copy.
Instruction *New;
if (NumInserted++ == 0) {
I.moveBefore(InsertPt);
New = &I;
} else {
New = I.clone();
if (!I.getName().empty())
New->setName(I.getName()+".le");
ExitBlock->getInstList().insert(InsertPt, New);
}
// Now that we have inserted the instruction, inform SSAUpdater.
if (!I.use_empty())
SSA.AddAvailableValue(ExitBlock, New);
}
// If the instruction doesn't dominate any exit blocks, it must be dead.
if (NumInserted == 0) {
CurAST->deleteValue(&I);
if (!I.use_empty())
I.replaceAllUsesWith(UndefValue::get(I.getType()));
I.eraseFromParent();
return;
}
// Next, rewrite uses of the instruction, inserting PHI nodes as needed.
for (Value::use_iterator UI = I.use_begin(), UE = I.use_end(); UI != UE; ) {
// Grab the use before incrementing the iterator.
Use &U = UI.getUse();
// Increment the iterator before removing the use from the list.
++UI;
SSA.RewriteUseAfterInsertions(U);
}
// Update CurAST for NewPHIs if I had pointer type.
if (I.getType()->isPointerTy())
for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i)
CurAST->copyValue(&I, NewPHIs[i]);
// Finally, remove the instruction from CurAST. It is no longer in the loop.
CurAST->deleteValue(&I);
}
/// ProcessInstruction - Given an instruction in the loop, check to see if it
/// has any uses that are outside the current loop. If so, insert LCSSA PHI
/// nodes and rewrite the uses.
bool LCSSA::ProcessInstruction(Instruction *Inst,
const SmallVectorImpl<BasicBlock*> &ExitBlocks) {
SmallVector<Use*, 16> UsesToRewrite;
BasicBlock *InstBB = Inst->getParent();
for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
UI != E; ++UI) {
User *U = *UI;
BasicBlock *UserBB = cast<Instruction>(U)->getParent();
if (PHINode *PN = dyn_cast<PHINode>(U))
UserBB = PN->getIncomingBlock(UI);
if (InstBB != UserBB && !inLoop(UserBB))
UsesToRewrite.push_back(&UI.getUse());
}
// If there are no uses outside the loop, exit with no change.
if (UsesToRewrite.empty()) return false;
++NumLCSSA; // We are applying the transformation
// Invoke instructions are special in that their result value is not available
// along their unwind edge. The code below tests to see whether DomBB dominates
// the value, so adjust DomBB to the normal destination block, which is
// effectively where the value is first usable.
BasicBlock *DomBB = Inst->getParent();
if (InvokeInst *Inv = dyn_cast<InvokeInst>(Inst))
DomBB = Inv->getNormalDest();
DomTreeNode *DomNode = DT->getNode(DomBB);
SSAUpdater SSAUpdate;
SSAUpdate.Initialize(Inst->getType(), Inst->getName());
// Insert the LCSSA phi's into all of the exit blocks dominated by the
// value, and add them to the Phi's map.
for (SmallVectorImpl<BasicBlock*>::const_iterator BBI = ExitBlocks.begin(),
BBE = ExitBlocks.end(); BBI != BBE; ++BBI) {
BasicBlock *ExitBB = *BBI;
if (!DT->dominates(DomNode, DT->getNode(ExitBB))) continue;
// If we already inserted something for this BB, don't reprocess it.
if (SSAUpdate.HasValueForBlock(ExitBB)) continue;
PHINode *PN = PHINode::Create(Inst->getType(), Inst->getName()+".lcssa",
ExitBB->begin());
PN->reserveOperandSpace(PredCache.GetNumPreds(ExitBB));
// Add inputs from inside the loop for this PHI.
for (BasicBlock **PI = PredCache.GetPreds(ExitBB); *PI; ++PI) {
PN->addIncoming(Inst, *PI);
// If the exit block has a predecessor not within the loop, arrange for
// the incoming value use corresponding to that predecessor to be
// rewritten in terms of a different LCSSA PHI.
if (!inLoop(*PI))
UsesToRewrite.push_back(
&PN->getOperandUse(
PN->getOperandNumForIncomingValue(PN->getNumIncomingValues()-1)));
}
// Remember that this phi makes the value alive in this block.
SSAUpdate.AddAvailableValue(ExitBB, PN);
}
// Rewrite all uses outside the loop in terms of the new PHIs we just
// inserted.
for (unsigned i = 0, e = UsesToRewrite.size(); i != e; ++i) {
// If this use is in an exit block, rewrite to use the newly inserted PHI.
// This is required for correctness because SSAUpdate doesn't handle uses in
// the same block. It assumes the PHI we inserted is at the end of the
// block.
Instruction *User = cast<Instruction>(UsesToRewrite[i]->getUser());
BasicBlock *UserBB = User->getParent();
if (PHINode *PN = dyn_cast<PHINode>(User))
UserBB = PN->getIncomingBlock(*UsesToRewrite[i]);
if (isa<PHINode>(UserBB->begin()) &&
isExitBlock(UserBB, ExitBlocks)) {
UsesToRewrite[i]->set(UserBB->begin());
continue;
}
// Otherwise, do full PHI insertion.
SSAUpdate.RewriteUse(*UsesToRewrite[i]);
}
return true;
}
