//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Constants.h"
-#include "llvm/GlobalAlias.h"
-#include "llvm/GlobalVariable.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Instructions.h"
-#include "llvm/Intrinsics.h"
-#include "llvm/IntrinsicInst.h"
#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/Hashing.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/EHPersonalities.h"
#include "llvm/Analysis/InstructionSimplify.h"
-#include "llvm/Analysis/ProfileInfo.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Support/CFG.h"
+#include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DIBuilder.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfo.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/GetElementPtrTypeIterator.h"
+#include "llvm/IR/GlobalAlias.h"
+#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/MDBuilder.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/Operator.h"
+#include "llvm/IR/ValueHandle.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
-#include "llvm/Support/ValueHandle.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
+#define DEBUG_TYPE "local"
+
+STATISTIC(NumRemoved, "Number of unreachable basic blocks removed");
+
//===----------------------------------------------------------------------===//
// Local constant propagation.
//
-// ConstantFoldTerminator - If a terminator instruction is predicated on a
-// constant value, convert it into an unconditional branch to the constant
-// destination.
-//
-bool llvm::ConstantFoldTerminator(BasicBlock *BB) {
+/// ConstantFoldTerminator - If a terminator instruction is predicated on a
+/// constant value, convert it into an unconditional branch to the constant
+/// destination. This is a nontrivial operation because the successors of this
+/// basic block must have their PHI nodes updated.
+/// Also calls RecursivelyDeleteTriviallyDeadInstructions() on any branch/switch
+/// conditions and indirectbr addresses this might make dead if
+/// DeleteDeadConditions is true.
+bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
+ const TargetLibraryInfo *TLI) {
TerminatorInst *T = BB->getTerminator();
+ IRBuilder<> Builder(T);
// Branch - See if we are conditional jumping on constant
if (BranchInst *BI = dyn_cast<BranchInst>(T)) {
// Let the basic block know that we are letting go of it. Based on this,
// it will adjust it's PHI nodes.
- assert(BI->getParent() && "Terminator not inserted in block!");
- OldDest->removePredecessor(BI->getParent());
+ OldDest->removePredecessor(BB);
- // Set the unconditional destination, and change the insn to be an
- // unconditional branch.
- BI->setUnconditionalDest(Destination);
+ // Replace the conditional branch with an unconditional one.
+ Builder.CreateBr(Destination);
+ BI->eraseFromParent();
return true;
}
-
+
if (Dest2 == Dest1) { // Conditional branch to same location?
// This branch matches something like this:
// br bool %cond, label %Dest, label %Dest
assert(BI->getParent() && "Terminator not inserted in block!");
Dest1->removePredecessor(BI->getParent());
- // Change a conditional branch to unconditional.
- BI->setUnconditionalDest(Dest1);
+ // Replace the conditional branch with an unconditional one.
+ Builder.CreateBr(Dest1);
+ Value *Cond = BI->getCondition();
+ BI->eraseFromParent();
+ if (DeleteDeadConditions)
+ RecursivelyDeleteTriviallyDeadInstructions(Cond, TLI);
return true;
}
return false;
}
-
+
if (SwitchInst *SI = dyn_cast<SwitchInst>(T)) {
- // If we are switching on a constant, we can convert the switch into a
- // single branch instruction!
+ // If we are switching on a constant, we can convert the switch to an
+ // unconditional branch.
ConstantInt *CI = dyn_cast<ConstantInt>(SI->getCondition());
- BasicBlock *TheOnlyDest = SI->getSuccessor(0); // The default dest
- BasicBlock *DefaultDest = TheOnlyDest;
- assert(TheOnlyDest == SI->getDefaultDest() &&
- "Default destination is not successor #0?");
+ BasicBlock *DefaultDest = SI->getDefaultDest();
+ BasicBlock *TheOnlyDest = DefaultDest;
+
+ // If the default is unreachable, ignore it when searching for TheOnlyDest.
+ if (isa<UnreachableInst>(DefaultDest->getFirstNonPHIOrDbg()) &&
+ SI->getNumCases() > 0) {
+ TheOnlyDest = SI->case_begin().getCaseSuccessor();
+ }
// Figure out which case it goes to.
- for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) {
+ for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
+ i != e; ++i) {
// Found case matching a constant operand?
- if (SI->getSuccessorValue(i) == CI) {
- TheOnlyDest = SI->getSuccessor(i);
+ if (i.getCaseValue() == CI) {
+ TheOnlyDest = i.getCaseSuccessor();
break;
}
// Check to see if this branch is going to the same place as the default
// dest. If so, eliminate it as an explicit compare.
- if (SI->getSuccessor(i) == DefaultDest) {
+ if (i.getCaseSuccessor() == DefaultDest) {
+ MDNode *MD = SI->getMetadata(LLVMContext::MD_prof);
+ unsigned NCases = SI->getNumCases();
+ // Fold the case metadata into the default if there will be any branches
+ // left, unless the metadata doesn't match the switch.
+ if (NCases > 1 && MD && MD->getNumOperands() == 2 + NCases) {
+ // Collect branch weights into a vector.
+ SmallVector<uint32_t, 8> Weights;
+ for (unsigned MD_i = 1, MD_e = MD->getNumOperands(); MD_i < MD_e;
+ ++MD_i) {
+ ConstantInt *CI =
+ mdconst::dyn_extract<ConstantInt>(MD->getOperand(MD_i));
+ assert(CI);
+ Weights.push_back(CI->getValue().getZExtValue());
+ }
+ // Merge weight of this case to the default weight.
+ unsigned idx = i.getCaseIndex();
+ Weights[0] += Weights[idx+1];
+ // Remove weight for this case.
+ std::swap(Weights[idx+1], Weights.back());
+ Weights.pop_back();
+ SI->setMetadata(LLVMContext::MD_prof,
+ MDBuilder(BB->getContext()).
+ createBranchWeights(Weights));
+ }
// Remove this entry.
DefaultDest->removePredecessor(SI->getParent());
SI->removeCase(i);
- --i; --e; // Don't skip an entry...
+ --i; --e;
continue;
}
// Otherwise, check to see if the switch only branches to one destination.
// We do this by reseting "TheOnlyDest" to null when we find two non-equal
// destinations.
- if (SI->getSuccessor(i) != TheOnlyDest) TheOnlyDest = 0;
+ if (i.getCaseSuccessor() != TheOnlyDest) TheOnlyDest = nullptr;
}
if (CI && !TheOnlyDest) {
// now.
if (TheOnlyDest) {
// Insert the new branch.
- BranchInst::Create(TheOnlyDest, SI);
+ Builder.CreateBr(TheOnlyDest);
BasicBlock *BB = SI->getParent();
// Remove entries from PHI nodes which we no longer branch to...
- for (unsigned i = 0, e = SI->getNumSuccessors(); i != e; ++i) {
+ for (BasicBlock *Succ : SI->successors()) {
// Found case matching a constant operand?
- BasicBlock *Succ = SI->getSuccessor(i);
if (Succ == TheOnlyDest)
- TheOnlyDest = 0; // Don't modify the first branch to TheOnlyDest
+ TheOnlyDest = nullptr; // Don't modify the first branch to TheOnlyDest
else
Succ->removePredecessor(BB);
}
// Delete the old switch.
- BB->getInstList().erase(SI);
+ Value *Cond = SI->getCondition();
+ SI->eraseFromParent();
+ if (DeleteDeadConditions)
+ RecursivelyDeleteTriviallyDeadInstructions(Cond, TLI);
return true;
}
-
- if (SI->getNumSuccessors() == 2) {
+
+ if (SI->getNumCases() == 1) {
// Otherwise, we can fold this switch into a conditional branch
// instruction if it has only one non-default destination.
- Value *Cond = new ICmpInst(SI, ICmpInst::ICMP_EQ, SI->getCondition(),
- SI->getSuccessorValue(1), "cond");
+ SwitchInst::CaseIt FirstCase = SI->case_begin();
+ Value *Cond = Builder.CreateICmpEQ(SI->getCondition(),
+ FirstCase.getCaseValue(), "cond");
+
// Insert the new branch.
- BranchInst::Create(SI->getSuccessor(1), SI->getSuccessor(0), Cond, SI);
+ BranchInst *NewBr = Builder.CreateCondBr(Cond,
+ FirstCase.getCaseSuccessor(),
+ SI->getDefaultDest());
+ MDNode *MD = SI->getMetadata(LLVMContext::MD_prof);
+ if (MD && MD->getNumOperands() == 3) {
+ ConstantInt *SICase =
+ mdconst::dyn_extract<ConstantInt>(MD->getOperand(2));
+ ConstantInt *SIDef =
+ mdconst::dyn_extract<ConstantInt>(MD->getOperand(1));
+ assert(SICase && SIDef);
+ // The TrueWeight should be the weight for the single case of SI.
+ NewBr->setMetadata(LLVMContext::MD_prof,
+ MDBuilder(BB->getContext()).
+ createBranchWeights(SICase->getValue().getZExtValue(),
+ SIDef->getValue().getZExtValue()));
+ }
+
+ // Update make.implicit metadata to the newly-created conditional branch.
+ MDNode *MakeImplicitMD = SI->getMetadata(LLVMContext::MD_make_implicit);
+ if (MakeImplicitMD)
+ NewBr->setMetadata(LLVMContext::MD_make_implicit, MakeImplicitMD);
// Delete the old switch.
SI->eraseFromParent();
dyn_cast<BlockAddress>(IBI->getAddress()->stripPointerCasts())) {
BasicBlock *TheOnlyDest = BA->getBasicBlock();
// Insert the new branch.
- BranchInst::Create(TheOnlyDest, IBI);
-
+ Builder.CreateBr(TheOnlyDest);
+
for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) {
if (IBI->getDestination(i) == TheOnlyDest)
- TheOnlyDest = 0;
+ TheOnlyDest = nullptr;
else
IBI->getDestination(i)->removePredecessor(IBI->getParent());
}
+ Value *Address = IBI->getAddress();
IBI->eraseFromParent();
-
+ if (DeleteDeadConditions)
+ RecursivelyDeleteTriviallyDeadInstructions(Address, TLI);
+
// If we didn't find our destination in the IBI successor list, then we
// have undefined behavior. Replace the unconditional branch with an
// 'unreachable' instruction.
BB->getTerminator()->eraseFromParent();
new UnreachableInst(BB->getContext(), BB);
}
-
+
return true;
}
}
-
+
return false;
}
/// isInstructionTriviallyDead - Return true if the result produced by the
/// instruction is not used, and the instruction has no side effects.
///
-bool llvm::isInstructionTriviallyDead(Instruction *I) {
+bool llvm::isInstructionTriviallyDead(Instruction *I,
+ const TargetLibraryInfo *TLI) {
if (!I->use_empty() || isa<TerminatorInst>(I)) return false;
- // We don't want debug info removed by anything this general.
- if (isa<DbgInfoIntrinsic>(I)) return false;
+ // We don't want the landingpad-like instructions removed by anything this
+ // general.
+ if (I->isEHPad())
+ return false;
+
+ // We don't want debug info removed by anything this general, unless
+ // debug info is empty.
+ if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(I)) {
+ if (DDI->getAddress())
+ return false;
+ return true;
+ }
+ if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(I)) {
+ if (DVI->getValue())
+ return false;
+ return true;
+ }
if (!I->mayHaveSideEffects()) return true;
// Special case intrinsics that "may have side effects" but can be deleted
// when dead.
- if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
// Safe to delete llvm.stacksave if dead.
if (II->getIntrinsicID() == Intrinsic::stacksave)
return true;
+
+ // Lifetime intrinsics are dead when their right-hand is undef.
+ if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
+ II->getIntrinsicID() == Intrinsic::lifetime_end)
+ return isa<UndefValue>(II->getArgOperand(1));
+
+ // Assumptions are dead if their condition is trivially true.
+ if (II->getIntrinsicID() == Intrinsic::assume) {
+ if (ConstantInt *Cond = dyn_cast<ConstantInt>(II->getArgOperand(0)))
+ return !Cond->isZero();
+
+ return false;
+ }
+ }
+
+ if (isAllocLikeFn(I, TLI)) return true;
+
+ if (CallInst *CI = isFreeCall(I, TLI))
+ if (Constant *C = dyn_cast<Constant>(CI->getArgOperand(0)))
+ return C->isNullValue() || isa<UndefValue>(C);
+
return false;
}
/// trivially dead instruction, delete it. If that makes any of its operands
/// trivially dead, delete them too, recursively. Return true if any
/// instructions were deleted.
-bool llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V) {
+bool
+llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V,
+ const TargetLibraryInfo *TLI) {
Instruction *I = dyn_cast<Instruction>(V);
- if (!I || !I->use_empty() || !isInstructionTriviallyDead(I))
+ if (!I || !I->use_empty() || !isInstructionTriviallyDead(I, TLI))
return false;
-
+
SmallVector<Instruction*, 16> DeadInsts;
DeadInsts.push_back(I);
-
+
do {
I = DeadInsts.pop_back_val();
// dead as we go.
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
Value *OpV = I->getOperand(i);
- I->setOperand(i, 0);
-
+ I->setOperand(i, nullptr);
+
if (!OpV->use_empty()) continue;
-
+
// If the operand is an instruction that became dead as we nulled out the
// operand, and if it is 'trivially' dead, delete it in a future loop
// iteration.
if (Instruction *OpI = dyn_cast<Instruction>(OpV))
- if (isInstructionTriviallyDead(OpI))
+ if (isInstructionTriviallyDead(OpI, TLI))
DeadInsts.push_back(OpI);
}
-
+
I->eraseFromParent();
} while (!DeadInsts.empty());
return true;
}
+/// areAllUsesEqual - Check whether the uses of a value are all the same.
+/// This is similar to Instruction::hasOneUse() except this will also return
+/// true when there are no uses or multiple uses that all refer to the same
+/// value.
+static bool areAllUsesEqual(Instruction *I) {
+ Value::user_iterator UI = I->user_begin();
+ Value::user_iterator UE = I->user_end();
+ if (UI == UE)
+ return true;
+
+ User *TheUse = *UI;
+ for (++UI; UI != UE; ++UI) {
+ if (*UI != TheUse)
+ return false;
+ }
+ return true;
+}
+
/// RecursivelyDeleteDeadPHINode - If the specified value is an effectively
/// dead PHI node, due to being a def-use chain of single-use nodes that
/// either forms a cycle or is terminated by a trivially dead instruction,
/// delete it. If that makes any of its operands trivially dead, delete them
-/// too, recursively. Return true if the PHI node is actually deleted.
-bool
-llvm::RecursivelyDeleteDeadPHINode(PHINode *PN) {
- // We can remove a PHI if it is on a cycle in the def-use graph
- // where each node in the cycle has degree one, i.e. only one use,
- // and is an instruction with no side effects.
- if (!PN->hasOneUse())
- return false;
+/// too, recursively. Return true if a change was made.
+bool llvm::RecursivelyDeleteDeadPHINode(PHINode *PN,
+ const TargetLibraryInfo *TLI) {
+ SmallPtrSet<Instruction*, 4> Visited;
+ for (Instruction *I = PN; areAllUsesEqual(I) && !I->mayHaveSideEffects();
+ I = cast<Instruction>(*I->user_begin())) {
+ if (I->use_empty())
+ return RecursivelyDeleteTriviallyDeadInstructions(I, TLI);
- bool Changed = false;
- SmallPtrSet<PHINode *, 4> PHIs;
- PHIs.insert(PN);
- for (Instruction *J = cast<Instruction>(*PN->use_begin());
- J->hasOneUse() && !J->mayHaveSideEffects();
- J = cast<Instruction>(*J->use_begin()))
- // If we find a PHI more than once, we're on a cycle that
+ // If we find an instruction more than once, we're on a cycle that
// won't prove fruitful.
- if (PHINode *JP = dyn_cast<PHINode>(J))
- if (!PHIs.insert(cast<PHINode>(JP))) {
- // Break the cycle and delete the PHI and its operands.
- JP->replaceAllUsesWith(UndefValue::get(JP->getType()));
- (void)RecursivelyDeleteTriviallyDeadInstructions(JP);
- Changed = true;
- break;
- }
- return Changed;
+ if (!Visited.insert(I).second) {
+ // Break the cycle and delete the instruction and its operands.
+ I->replaceAllUsesWith(UndefValue::get(I->getType()));
+ (void)RecursivelyDeleteTriviallyDeadInstructions(I, TLI);
+ return true;
+ }
+ }
+ return false;
+}
+
+static bool
+simplifyAndDCEInstruction(Instruction *I,
+ SmallSetVector<Instruction *, 16> &WorkList,
+ const DataLayout &DL,
+ const TargetLibraryInfo *TLI) {
+ if (isInstructionTriviallyDead(I, TLI)) {
+ // Null out all of the instruction's operands to see if any operand becomes
+ // dead as we go.
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
+ Value *OpV = I->getOperand(i);
+ I->setOperand(i, nullptr);
+
+ if (!OpV->use_empty() || I == OpV)
+ continue;
+
+ // If the operand is an instruction that became dead as we nulled out the
+ // operand, and if it is 'trivially' dead, delete it in a future loop
+ // iteration.
+ if (Instruction *OpI = dyn_cast<Instruction>(OpV))
+ if (isInstructionTriviallyDead(OpI, TLI))
+ WorkList.insert(OpI);
+ }
+
+ I->eraseFromParent();
+
+ return true;
+ }
+
+ if (Value *SimpleV = SimplifyInstruction(I, DL)) {
+ // Add the users to the worklist. CAREFUL: an instruction can use itself,
+ // in the case of a phi node.
+ for (User *U : I->users())
+ if (U != I)
+ WorkList.insert(cast<Instruction>(U));
+
+ // Replace the instruction with its simplified value.
+ I->replaceAllUsesWith(SimpleV);
+ I->eraseFromParent();
+ return true;
+ }
+ return false;
}
/// SimplifyInstructionsInBlock - Scan the specified basic block and try to
///
/// This returns true if it changed the code, note that it can delete
/// instructions in other blocks as well in this block.
-bool llvm::SimplifyInstructionsInBlock(BasicBlock *BB, const TargetData *TD) {
+bool llvm::SimplifyInstructionsInBlock(BasicBlock *BB,
+ const TargetLibraryInfo *TLI) {
bool MadeChange = false;
- for (BasicBlock::iterator BI = BB->begin(), E = BB->end(); BI != E; ) {
- Instruction *Inst = BI++;
-
- if (Value *V = SimplifyInstruction(Inst, TD)) {
- WeakVH BIHandle(BI);
- ReplaceAndSimplifyAllUses(Inst, V, TD);
- MadeChange = true;
- if (BIHandle != BI)
- BI = BB->begin();
- continue;
- }
-
- MadeChange |= RecursivelyDeleteTriviallyDeadInstructions(Inst);
+ const DataLayout &DL = BB->getModule()->getDataLayout();
+
+#ifndef NDEBUG
+ // In debug builds, ensure that the terminator of the block is never replaced
+ // or deleted by these simplifications. The idea of simplification is that it
+ // cannot introduce new instructions, and there is no way to replace the
+ // terminator of a block without introducing a new instruction.
+ AssertingVH<Instruction> TerminatorVH(&BB->back());
+#endif
+
+ SmallSetVector<Instruction *, 16> WorkList;
+ // Iterate over the original function, only adding insts to the worklist
+ // if they actually need to be revisited. This avoids having to pre-init
+ // the worklist with the entire function's worth of instructions.
+ for (BasicBlock::iterator BI = BB->begin(), E = std::prev(BB->end()); BI != E;) {
+ assert(!BI->isTerminator());
+ Instruction *I = &*BI;
+ ++BI;
+
+ // We're visiting this instruction now, so make sure it's not in the
+ // worklist from an earlier visit.
+ if (!WorkList.count(I))
+ MadeChange |= simplifyAndDCEInstruction(I, WorkList, DL, TLI);
+ }
+
+ while (!WorkList.empty()) {
+ Instruction *I = WorkList.pop_back_val();
+ MadeChange |= simplifyAndDCEInstruction(I, WorkList, DL, TLI);
}
return MadeChange;
}
///
/// .. and delete the predecessor corresponding to the '1', this will attempt to
/// recursively fold the and to 0.
-void llvm::RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred,
- TargetData *TD) {
+void llvm::RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred) {
// This only adjusts blocks with PHI nodes.
if (!isa<PHINode>(BB->begin()))
return;
-
+
// Remove the entries for Pred from the PHI nodes in BB, but do not simplify
// them down. This will leave us with single entry phi nodes and other phis
// that can be removed.
BB->removePredecessor(Pred, true);
-
+
WeakVH PhiIt = &BB->front();
while (PHINode *PN = dyn_cast<PHINode>(PhiIt)) {
PhiIt = &*++BasicBlock::iterator(cast<Instruction>(PhiIt));
+ Value *OldPhiIt = PhiIt;
- Value *PNV = SimplifyInstruction(PN, TD);
- if (PNV == 0) continue;
+ if (!recursivelySimplifyInstruction(PN))
+ continue;
- // If we're able to simplify the phi to a single value, substitute the new
- // value into all of its uses.
- assert(PNV != PN && "SimplifyInstruction broken!");
-
- Value *OldPhiIt = PhiIt;
- ReplaceAndSimplifyAllUses(PN, PNV, TD);
-
// If recursive simplification ended up deleting the next PHI node we would
// iterate to, then our iterator is invalid, restart scanning from the top
// of the block.
/// between them, moving the instructions in the predecessor into DestBB and
/// deleting the predecessor block.
///
-void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, Pass *P) {
+void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, DominatorTree *DT) {
// If BB has single-entry PHI nodes, fold them.
while (PHINode *PN = dyn_cast<PHINode>(DestBB->begin())) {
Value *NewVal = PN->getIncomingValue(0);
PN->replaceAllUsesWith(NewVal);
PN->eraseFromParent();
}
-
+
BasicBlock *PredBB = DestBB->getSinglePredecessor();
assert(PredBB && "Block doesn't have a single predecessor!");
-
- // Splice all the instructions from PredBB to DestBB.
- PredBB->getTerminator()->eraseFromParent();
- DestBB->getInstList().splice(DestBB->begin(), PredBB->getInstList());
// Zap anything that took the address of DestBB. Not doing this will give the
// address an invalid value.
BA->getType()));
BA->destroyConstant();
}
-
+
// Anything that branched to PredBB now branches to DestBB.
PredBB->replaceAllUsesWith(DestBB);
-
- if (P) {
- ProfileInfo *PI = P->getAnalysisIfAvailable<ProfileInfo>();
- if (PI) {
- PI->replaceAllUses(PredBB, DestBB);
- PI->removeEdge(ProfileInfo::getEdge(PredBB, DestBB));
- }
+
+ // Splice all the instructions from PredBB to DestBB.
+ PredBB->getTerminator()->eraseFromParent();
+ DestBB->getInstList().splice(DestBB->begin(), PredBB->getInstList());
+
+ // If the PredBB is the entry block of the function, move DestBB up to
+ // become the entry block after we erase PredBB.
+ if (PredBB == &DestBB->getParent()->getEntryBlock())
+ DestBB->moveAfter(PredBB);
+
+ if (DT) {
+ BasicBlock *PredBBIDom = DT->getNode(PredBB)->getIDom()->getBlock();
+ DT->changeImmediateDominator(DestBB, PredBBIDom);
+ DT->eraseNode(PredBB);
}
// Nuke BB.
PredBB->eraseFromParent();
}
+/// CanMergeValues - Return true if we can choose one of these values to use
+/// in place of the other. Note that we will always choose the non-undef
+/// value to keep.
+static bool CanMergeValues(Value *First, Value *Second) {
+ return First == Second || isa<UndefValue>(First) || isa<UndefValue>(Second);
+}
+
/// CanPropagatePredecessorsForPHIs - Return true if we can fold BB, an
-/// almost-empty BB ending in an unconditional branch to Succ, into succ.
+/// almost-empty BB ending in an unconditional branch to Succ, into Succ.
///
/// Assumption: Succ is the single successor for BB.
///
static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
assert(*succ_begin(BB) == Succ && "Succ is not successor of BB!");
- DEBUG(dbgs() << "Looking to fold " << BB->getName() << " into "
+ DEBUG(dbgs() << "Looking to fold " << BB->getName() << " into "
<< Succ->getName() << "\n");
// Shortcut, if there is only a single predecessor it must be BB and merging
// is always safe
if (Succ->getSinglePredecessor()) return true;
// Make a list of the predecessors of BB
- typedef SmallPtrSet<BasicBlock*, 16> BlockSet;
- BlockSet BBPreds(pred_begin(BB), pred_end(BB));
-
- // Use that list to make another list of common predecessors of BB and Succ
- BlockSet CommonPreds;
- for (pred_iterator PI = pred_begin(Succ), PE = pred_end(Succ);
- PI != PE; ++PI) {
- BasicBlock *P = *PI;
- if (BBPreds.count(P))
- CommonPreds.insert(P);
- }
+ SmallPtrSet<BasicBlock*, 16> BBPreds(pred_begin(BB), pred_end(BB));
- // Shortcut, if there are no common predecessors, merging is always safe
- if (CommonPreds.empty())
- return true;
-
// Look at all the phi nodes in Succ, to see if they present a conflict when
// merging these blocks
for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
// merge the phi nodes and then the blocks can still be merged
PHINode *BBPN = dyn_cast<PHINode>(PN->getIncomingValueForBlock(BB));
if (BBPN && BBPN->getParent() == BB) {
- for (BlockSet::iterator PI = CommonPreds.begin(), PE = CommonPreds.end();
- PI != PE; PI++) {
- if (BBPN->getIncomingValueForBlock(*PI)
- != PN->getIncomingValueForBlock(*PI)) {
- DEBUG(dbgs() << "Can't fold, phi node " << PN->getName() << " in "
- << Succ->getName() << " is conflicting with "
+ for (unsigned PI = 0, PE = PN->getNumIncomingValues(); PI != PE; ++PI) {
+ BasicBlock *IBB = PN->getIncomingBlock(PI);
+ if (BBPreds.count(IBB) &&
+ !CanMergeValues(BBPN->getIncomingValueForBlock(IBB),
+ PN->getIncomingValue(PI))) {
+ DEBUG(dbgs() << "Can't fold, phi node " << PN->getName() << " in "
+ << Succ->getName() << " is conflicting with "
<< BBPN->getName() << " with regard to common predecessor "
- << (*PI)->getName() << "\n");
+ << IBB->getName() << "\n");
return false;
}
}
} else {
Value* Val = PN->getIncomingValueForBlock(BB);
- for (BlockSet::iterator PI = CommonPreds.begin(), PE = CommonPreds.end();
- PI != PE; PI++) {
+ for (unsigned PI = 0, PE = PN->getNumIncomingValues(); PI != PE; ++PI) {
// See if the incoming value for the common predecessor is equal to the
// one for BB, in which case this phi node will not prevent the merging
// of the block.
- if (Val != PN->getIncomingValueForBlock(*PI)) {
- DEBUG(dbgs() << "Can't fold, phi node " << PN->getName() << " in "
+ BasicBlock *IBB = PN->getIncomingBlock(PI);
+ if (BBPreds.count(IBB) &&
+ !CanMergeValues(Val, PN->getIncomingValue(PI))) {
+ DEBUG(dbgs() << "Can't fold, phi node " << PN->getName() << " in "
<< Succ->getName() << " is conflicting with regard to common "
- << "predecessor " << (*PI)->getName() << "\n");
+ << "predecessor " << IBB->getName() << "\n");
return false;
}
}
return true;
}
+typedef SmallVector<BasicBlock *, 16> PredBlockVector;
+typedef DenseMap<BasicBlock *, Value *> IncomingValueMap;
+
+/// \brief Determines the value to use as the phi node input for a block.
+///
+/// Select between \p OldVal any value that we know flows from \p BB
+/// to a particular phi on the basis of which one (if either) is not
+/// undef. Update IncomingValues based on the selected value.
+///
+/// \param OldVal The value we are considering selecting.
+/// \param BB The block that the value flows in from.
+/// \param IncomingValues A map from block-to-value for other phi inputs
+/// that we have examined.
+///
+/// \returns the selected value.
+static Value *selectIncomingValueForBlock(Value *OldVal, BasicBlock *BB,
+ IncomingValueMap &IncomingValues) {
+ if (!isa<UndefValue>(OldVal)) {
+ assert((!IncomingValues.count(BB) ||
+ IncomingValues.find(BB)->second == OldVal) &&
+ "Expected OldVal to match incoming value from BB!");
+
+ IncomingValues.insert(std::make_pair(BB, OldVal));
+ return OldVal;
+ }
+
+ IncomingValueMap::const_iterator It = IncomingValues.find(BB);
+ if (It != IncomingValues.end()) return It->second;
+
+ return OldVal;
+}
+
+/// \brief Create a map from block to value for the operands of a
+/// given phi.
+///
+/// Create a map from block to value for each non-undef value flowing
+/// into \p PN.
+///
+/// \param PN The phi we are collecting the map for.
+/// \param IncomingValues [out] The map from block to value for this phi.
+static void gatherIncomingValuesToPhi(PHINode *PN,
+ IncomingValueMap &IncomingValues) {
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ BasicBlock *BB = PN->getIncomingBlock(i);
+ Value *V = PN->getIncomingValue(i);
+
+ if (!isa<UndefValue>(V))
+ IncomingValues.insert(std::make_pair(BB, V));
+ }
+}
+
+/// \brief Replace the incoming undef values to a phi with the values
+/// from a block-to-value map.
+///
+/// \param PN The phi we are replacing the undefs in.
+/// \param IncomingValues A map from block to value.
+static void replaceUndefValuesInPhi(PHINode *PN,
+ const IncomingValueMap &IncomingValues) {
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ Value *V = PN->getIncomingValue(i);
+
+ if (!isa<UndefValue>(V)) continue;
+
+ BasicBlock *BB = PN->getIncomingBlock(i);
+ IncomingValueMap::const_iterator It = IncomingValues.find(BB);
+ if (It == IncomingValues.end()) continue;
+
+ PN->setIncomingValue(i, It->second);
+ }
+}
+
+/// \brief Replace a value flowing from a block to a phi with
+/// potentially multiple instances of that value flowing from the
+/// block's predecessors to the phi.
+///
+/// \param BB The block with the value flowing into the phi.
+/// \param BBPreds The predecessors of BB.
+/// \param PN The phi that we are updating.
+static void redirectValuesFromPredecessorsToPhi(BasicBlock *BB,
+ const PredBlockVector &BBPreds,
+ PHINode *PN) {
+ Value *OldVal = PN->removeIncomingValue(BB, false);
+ assert(OldVal && "No entry in PHI for Pred BB!");
+
+ IncomingValueMap IncomingValues;
+
+ // We are merging two blocks - BB, and the block containing PN - and
+ // as a result we need to redirect edges from the predecessors of BB
+ // to go to the block containing PN, and update PN
+ // accordingly. Since we allow merging blocks in the case where the
+ // predecessor and successor blocks both share some predecessors,
+ // and where some of those common predecessors might have undef
+ // values flowing into PN, we want to rewrite those values to be
+ // consistent with the non-undef values.
+
+ gatherIncomingValuesToPhi(PN, IncomingValues);
+
+ // If this incoming value is one of the PHI nodes in BB, the new entries
+ // in the PHI node are the entries from the old PHI.
+ if (isa<PHINode>(OldVal) && cast<PHINode>(OldVal)->getParent() == BB) {
+ PHINode *OldValPN = cast<PHINode>(OldVal);
+ for (unsigned i = 0, e = OldValPN->getNumIncomingValues(); i != e; ++i) {
+ // Note that, since we are merging phi nodes and BB and Succ might
+ // have common predecessors, we could end up with a phi node with
+ // identical incoming branches. This will be cleaned up later (and
+ // will trigger asserts if we try to clean it up now, without also
+ // simplifying the corresponding conditional branch).
+ BasicBlock *PredBB = OldValPN->getIncomingBlock(i);
+ Value *PredVal = OldValPN->getIncomingValue(i);
+ Value *Selected = selectIncomingValueForBlock(PredVal, PredBB,
+ IncomingValues);
+
+ // And add a new incoming value for this predecessor for the
+ // newly retargeted branch.
+ PN->addIncoming(Selected, PredBB);
+ }
+ } else {
+ for (unsigned i = 0, e = BBPreds.size(); i != e; ++i) {
+ // Update existing incoming values in PN for this
+ // predecessor of BB.
+ BasicBlock *PredBB = BBPreds[i];
+ Value *Selected = selectIncomingValueForBlock(OldVal, PredBB,
+ IncomingValues);
+
+ // And add a new incoming value for this predecessor for the
+ // newly retargeted branch.
+ PN->addIncoming(Selected, PredBB);
+ }
+ }
+
+ replaceUndefValuesInPhi(PN, IncomingValues);
+}
+
/// TryToSimplifyUncondBranchFromEmptyBlock - BB is known to contain an
/// unconditional branch, and contains no instructions other than PHI nodes,
-/// potential debug intrinsics and the branch. If possible, eliminate BB by
-/// rewriting all the predecessors to branch to the successor block and return
-/// true. If we can't transform, return false.
+/// potential side-effect free intrinsics and the branch. If possible,
+/// eliminate BB by rewriting all the predecessors to branch to the successor
+/// block and return true. If we can't transform, return false.
bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB) {
assert(BB != &BB->getParent()->getEntryBlock() &&
"TryToSimplifyUncondBranchFromEmptyBlock called on entry block!");
// We can't eliminate infinite loops.
BasicBlock *Succ = cast<BranchInst>(BB->getTerminator())->getSuccessor(0);
if (BB == Succ) return false;
-
+
// Check to see if merging these blocks would cause conflicts for any of the
// phi nodes in BB or Succ. If not, we can safely merge.
if (!CanPropagatePredecessorsForPHIs(BB, Succ)) return false;
// possible to handle such cases, but difficult: it requires checking whether
// BB dominates Succ, which is non-trivial to calculate in the case where
// Succ has multiple predecessors. Also, it requires checking whether
- // constructing the necessary self-referential PHI node doesn't intoduce any
+ // constructing the necessary self-referential PHI node doesn't introduce any
// conflicts; this isn't too difficult, but the previous code for doing this
// was incorrect.
//
if (!Succ->getSinglePredecessor()) {
BasicBlock::iterator BBI = BB->begin();
while (isa<PHINode>(*BBI)) {
- for (Value::use_iterator UI = BBI->use_begin(), E = BBI->use_end();
- UI != E; ++UI) {
- if (PHINode* PN = dyn_cast<PHINode>(*UI)) {
- if (PN->getIncomingBlock(UI) != BB)
+ for (Use &U : BBI->uses()) {
+ if (PHINode* PN = dyn_cast<PHINode>(U.getUser())) {
+ if (PN->getIncomingBlock(U) != BB)
return false;
} else {
return false;
}
DEBUG(dbgs() << "Killing Trivial BB: \n" << *BB);
-
+
if (isa<PHINode>(Succ->begin())) {
// If there is more than one pred of succ, and there are PHI nodes in
// the successor, then we need to add incoming edges for the PHI nodes
//
- const SmallVector<BasicBlock*, 16> BBPreds(pred_begin(BB), pred_end(BB));
-
+ const PredBlockVector BBPreds(pred_begin(BB), pred_end(BB));
+
// Loop over all of the PHI nodes in the successor of BB.
for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
PHINode *PN = cast<PHINode>(I);
- Value *OldVal = PN->removeIncomingValue(BB, false);
- assert(OldVal && "No entry in PHI for Pred BB!");
-
- // If this incoming value is one of the PHI nodes in BB, the new entries
- // in the PHI node are the entries from the old PHI.
- if (isa<PHINode>(OldVal) && cast<PHINode>(OldVal)->getParent() == BB) {
- PHINode *OldValPN = cast<PHINode>(OldVal);
- for (unsigned i = 0, e = OldValPN->getNumIncomingValues(); i != e; ++i)
- // Note that, since we are merging phi nodes and BB and Succ might
- // have common predecessors, we could end up with a phi node with
- // identical incoming branches. This will be cleaned up later (and
- // will trigger asserts if we try to clean it up now, without also
- // simplifying the corresponding conditional branch).
- PN->addIncoming(OldValPN->getIncomingValue(i),
- OldValPN->getIncomingBlock(i));
- } else {
- // Add an incoming value for each of the new incoming values.
- for (unsigned i = 0, e = BBPreds.size(); i != e; ++i)
- PN->addIncoming(OldVal, BBPreds[i]);
- }
+
+ redirectValuesFromPredecessorsToPhi(BB, BBPreds, PN);
}
}
-
- while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
- if (Succ->getSinglePredecessor()) {
- // BB is the only predecessor of Succ, so Succ will end up with exactly
- // the same predecessors BB had.
- Succ->getInstList().splice(Succ->begin(),
- BB->getInstList(), BB->begin());
- } else {
+
+ if (Succ->getSinglePredecessor()) {
+ // BB is the only predecessor of Succ, so Succ will end up with exactly
+ // the same predecessors BB had.
+
+ // Copy over any phi, debug or lifetime instruction.
+ BB->getTerminator()->eraseFromParent();
+ Succ->getInstList().splice(Succ->getFirstNonPHI()->getIterator(),
+ BB->getInstList());
+ } else {
+ while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
// We explicitly check for such uses in CanPropagatePredecessorsForPHIs.
assert(PN->use_empty() && "There shouldn't be any uses here!");
PN->eraseFromParent();
}
}
-
+
// Everything that jumped to BB now goes to Succ.
BB->replaceAllUsesWith(Succ);
if (!Succ->hasName()) Succ->takeName(BB);
/// orders them so it usually won't matter.
///
bool llvm::EliminateDuplicatePHINodes(BasicBlock *BB) {
- bool Changed = false;
-
// This implementation doesn't currently consider undef operands
- // specially. Theroetically, two phis which are identical except for
+ // specially. Theoretically, two phis which are identical except for
// one having an undef where the other doesn't could be collapsed.
- // Map from PHI hash values to PHI nodes. If multiple PHIs have
- // the same hash value, the element is the first PHI in the
- // linked list in CollisionMap.
- DenseMap<uintptr_t, PHINode *> HashMap;
+ struct PHIDenseMapInfo {
+ static PHINode *getEmptyKey() {
+ return DenseMapInfo<PHINode *>::getEmptyKey();
+ }
+ static PHINode *getTombstoneKey() {
+ return DenseMapInfo<PHINode *>::getTombstoneKey();
+ }
+ static unsigned getHashValue(PHINode *PN) {
+ // Compute a hash value on the operands. Instcombine will likely have
+ // sorted them, which helps expose duplicates, but we have to check all
+ // the operands to be safe in case instcombine hasn't run.
+ return static_cast<unsigned>(hash_combine(
+ hash_combine_range(PN->value_op_begin(), PN->value_op_end()),
+ hash_combine_range(PN->block_begin(), PN->block_end())));
+ }
+ static bool isEqual(PHINode *LHS, PHINode *RHS) {
+ if (LHS == getEmptyKey() || LHS == getTombstoneKey() ||
+ RHS == getEmptyKey() || RHS == getTombstoneKey())
+ return LHS == RHS;
+ return LHS->isIdenticalTo(RHS);
+ }
+ };
- // Maintain linked lists of PHI nodes with common hash values.
- DenseMap<PHINode *, PHINode *> CollisionMap;
+ // Set of unique PHINodes.
+ DenseSet<PHINode *, PHIDenseMapInfo> PHISet;
// Examine each PHI.
- for (BasicBlock::iterator I = BB->begin();
- PHINode *PN = dyn_cast<PHINode>(I++); ) {
- // Compute a hash value on the operands. Instcombine will likely have sorted
- // them, which helps expose duplicates, but we have to check all the
- // operands to be safe in case instcombine hasn't run.
- uintptr_t Hash = 0;
- for (User::op_iterator I = PN->op_begin(), E = PN->op_end(); I != E; ++I) {
- // This hash algorithm is quite weak as hash functions go, but it seems
- // to do a good enough job for this particular purpose, and is very quick.
- Hash ^= reinterpret_cast<uintptr_t>(static_cast<Value *>(*I));
- Hash = (Hash << 7) | (Hash >> (sizeof(uintptr_t) * CHAR_BIT - 7));
+ bool Changed = false;
+ for (auto I = BB->begin(); PHINode *PN = dyn_cast<PHINode>(I++);) {
+ auto Inserted = PHISet.insert(PN);
+ if (!Inserted.second) {
+ // A duplicate. Replace this PHI with its duplicate.
+ PN->replaceAllUsesWith(*Inserted.first);
+ PN->eraseFromParent();
+ Changed = true;
+
+ // The RAUW can change PHIs that we already visited. Start over from the
+ // beginning.
+ PHISet.clear();
+ I = BB->begin();
}
- // If we've never seen this hash value before, it's a unique PHI.
- std::pair<DenseMap<uintptr_t, PHINode *>::iterator, bool> Pair =
- HashMap.insert(std::make_pair(Hash, PN));
- if (Pair.second) continue;
- // Otherwise it's either a duplicate or a hash collision.
- for (PHINode *OtherPN = Pair.first->second; ; ) {
- if (OtherPN->isIdenticalTo(PN)) {
- // A duplicate. Replace this PHI with its duplicate.
- PN->replaceAllUsesWith(OtherPN);
- PN->eraseFromParent();
+ }
+
+ return Changed;
+}
+
+/// enforceKnownAlignment - If the specified pointer points to an object that
+/// we control, modify the object's alignment to PrefAlign. This isn't
+/// often possible though. If alignment is important, a more reliable approach
+/// is to simply align all global variables and allocation instructions to
+/// their preferred alignment from the beginning.
+///
+static unsigned enforceKnownAlignment(Value *V, unsigned Align,
+ unsigned PrefAlign,
+ const DataLayout &DL) {
+ V = V->stripPointerCasts();
+
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
+ // If the preferred alignment is greater than the natural stack alignment
+ // then don't round up. This avoids dynamic stack realignment.
+ if (DL.exceedsNaturalStackAlignment(PrefAlign))
+ return Align;
+ // If there is a requested alignment and if this is an alloca, round up.
+ if (AI->getAlignment() >= PrefAlign)
+ return AI->getAlignment();
+ AI->setAlignment(PrefAlign);
+ return PrefAlign;
+ }
+
+ if (auto *GO = dyn_cast<GlobalObject>(V)) {
+ // If there is a large requested alignment and we can, bump up the alignment
+ // of the global. If the memory we set aside for the global may not be the
+ // memory used by the final program then it is impossible for us to reliably
+ // enforce the preferred alignment.
+ if (!GO->isStrongDefinitionForLinker())
+ return Align;
+
+ if (GO->getAlignment() >= PrefAlign)
+ return GO->getAlignment();
+ // We can only increase the alignment of the global if it has no alignment
+ // specified or if it is not assigned a section. If it is assigned a
+ // section, the global could be densely packed with other objects in the
+ // section, increasing the alignment could cause padding issues.
+ if (!GO->hasSection() || GO->getAlignment() == 0)
+ GO->setAlignment(PrefAlign);
+ return GO->getAlignment();
+ }
+
+ return Align;
+}
+
+/// getOrEnforceKnownAlignment - If the specified pointer has an alignment that
+/// we can determine, return it, otherwise return 0. If PrefAlign is specified,
+/// and it is more than the alignment of the ultimate object, see if we can
+/// increase the alignment of the ultimate object, making this check succeed.
+unsigned llvm::getOrEnforceKnownAlignment(Value *V, unsigned PrefAlign,
+ const DataLayout &DL,
+ const Instruction *CxtI,
+ AssumptionCache *AC,
+ const DominatorTree *DT) {
+ assert(V->getType()->isPointerTy() &&
+ "getOrEnforceKnownAlignment expects a pointer!");
+ unsigned BitWidth = DL.getPointerTypeSizeInBits(V->getType());
+
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ computeKnownBits(V, KnownZero, KnownOne, DL, 0, AC, CxtI, DT);
+ unsigned TrailZ = KnownZero.countTrailingOnes();
+
+ // Avoid trouble with ridiculously large TrailZ values, such as
+ // those computed from a null pointer.
+ TrailZ = std::min(TrailZ, unsigned(sizeof(unsigned) * CHAR_BIT - 1));
+
+ unsigned Align = 1u << std::min(BitWidth - 1, TrailZ);
+
+ // LLVM doesn't support alignments larger than this currently.
+ Align = std::min(Align, +Value::MaximumAlignment);
+
+ if (PrefAlign > Align)
+ Align = enforceKnownAlignment(V, Align, PrefAlign, DL);
+
+ // We don't need to make any adjustment.
+ return Align;
+}
+
+///===---------------------------------------------------------------------===//
+/// Dbg Intrinsic utilities
+///
+
+/// See if there is a dbg.value intrinsic for DIVar before I.
+static bool LdStHasDebugValue(const DILocalVariable *DIVar, Instruction *I) {
+ // Since we can't guarantee that the original dbg.declare instrinsic
+ // is removed by LowerDbgDeclare(), we need to make sure that we are
+ // not inserting the same dbg.value intrinsic over and over.
+ llvm::BasicBlock::InstListType::iterator PrevI(I);
+ if (PrevI != I->getParent()->getInstList().begin()) {
+ --PrevI;
+ if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(PrevI))
+ if (DVI->getValue() == I->getOperand(0) &&
+ DVI->getOffset() == 0 &&
+ DVI->getVariable() == DIVar)
+ return true;
+ }
+ return false;
+}
+
+/// Inserts a llvm.dbg.value intrinsic before a store to an alloca'd value
+/// that has an associated llvm.dbg.decl intrinsic.
+bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+ StoreInst *SI, DIBuilder &Builder) {
+ auto *DIVar = DDI->getVariable();
+ auto *DIExpr = DDI->getExpression();
+ assert(DIVar && "Missing variable");
+
+ if (LdStHasDebugValue(DIVar, SI))
+ return true;
+
+ // If an argument is zero extended then use argument directly. The ZExt
+ // may be zapped by an optimization pass in future.
+ Argument *ExtendedArg = nullptr;
+ if (ZExtInst *ZExt = dyn_cast<ZExtInst>(SI->getOperand(0)))
+ ExtendedArg = dyn_cast<Argument>(ZExt->getOperand(0));
+ if (SExtInst *SExt = dyn_cast<SExtInst>(SI->getOperand(0)))
+ ExtendedArg = dyn_cast<Argument>(SExt->getOperand(0));
+ if (ExtendedArg)
+ Builder.insertDbgValueIntrinsic(ExtendedArg, 0, DIVar, DIExpr,
+ DDI->getDebugLoc(), SI);
+ else
+ Builder.insertDbgValueIntrinsic(SI->getOperand(0), 0, DIVar, DIExpr,
+ DDI->getDebugLoc(), SI);
+ return true;
+}
+
+/// Inserts a llvm.dbg.value intrinsic before a load of an alloca'd value
+/// that has an associated llvm.dbg.decl intrinsic.
+bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+ LoadInst *LI, DIBuilder &Builder) {
+ auto *DIVar = DDI->getVariable();
+ auto *DIExpr = DDI->getExpression();
+ assert(DIVar && "Missing variable");
+
+ if (LdStHasDebugValue(DIVar, LI))
+ return true;
+
+ Builder.insertDbgValueIntrinsic(LI->getOperand(0), 0, DIVar, DIExpr,
+ DDI->getDebugLoc(), LI);
+ return true;
+}
+
+/// Determine whether this alloca is either a VLA or an array.
+static bool isArray(AllocaInst *AI) {
+ return AI->isArrayAllocation() ||
+ AI->getType()->getElementType()->isArrayTy();
+}
+
+/// LowerDbgDeclare - Lowers llvm.dbg.declare intrinsics into appropriate set
+/// of llvm.dbg.value intrinsics.
+bool llvm::LowerDbgDeclare(Function &F) {
+ DIBuilder DIB(*F.getParent(), /*AllowUnresolved*/ false);
+ SmallVector<DbgDeclareInst *, 4> Dbgs;
+ for (auto &FI : F)
+ for (Instruction &BI : FI)
+ if (auto DDI = dyn_cast<DbgDeclareInst>(&BI))
+ Dbgs.push_back(DDI);
+
+ if (Dbgs.empty())
+ return false;
+
+ for (auto &I : Dbgs) {
+ DbgDeclareInst *DDI = I;
+ AllocaInst *AI = dyn_cast_or_null<AllocaInst>(DDI->getAddress());
+ // If this is an alloca for a scalar variable, insert a dbg.value
+ // at each load and store to the alloca and erase the dbg.declare.
+ // The dbg.values allow tracking a variable even if it is not
+ // stored on the stack, while the dbg.declare can only describe
+ // the stack slot (and at a lexical-scope granularity). Later
+ // passes will attempt to elide the stack slot.
+ if (AI && !isArray(AI)) {
+ for (User *U : AI->users())
+ if (StoreInst *SI = dyn_cast<StoreInst>(U))
+ ConvertDebugDeclareToDebugValue(DDI, SI, DIB);
+ else if (LoadInst *LI = dyn_cast<LoadInst>(U))
+ ConvertDebugDeclareToDebugValue(DDI, LI, DIB);
+ else if (CallInst *CI = dyn_cast<CallInst>(U)) {
+ // This is a call by-value or some other instruction that
+ // takes a pointer to the variable. Insert a *value*
+ // intrinsic that describes the alloca.
+ DIB.insertDbgValueIntrinsic(AI, 0, DDI->getVariable(),
+ DDI->getExpression(), DDI->getDebugLoc(),
+ CI);
+ }
+ DDI->eraseFromParent();
+ }
+ }
+ return true;
+}
+
+/// FindAllocaDbgDeclare - Finds the llvm.dbg.declare intrinsic describing the
+/// alloca 'V', if any.
+DbgDeclareInst *llvm::FindAllocaDbgDeclare(Value *V) {
+ if (auto *L = LocalAsMetadata::getIfExists(V))
+ if (auto *MDV = MetadataAsValue::getIfExists(V->getContext(), L))
+ for (User *U : MDV->users())
+ if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(U))
+ return DDI;
+
+ return nullptr;
+}
+
+bool llvm::replaceDbgDeclare(Value *Address, Value *NewAddress,
+ Instruction *InsertBefore, DIBuilder &Builder,
+ bool Deref, int Offset) {
+ DbgDeclareInst *DDI = FindAllocaDbgDeclare(Address);
+ if (!DDI)
+ return false;
+ DebugLoc Loc = DDI->getDebugLoc();
+ auto *DIVar = DDI->getVariable();
+ auto *DIExpr = DDI->getExpression();
+ assert(DIVar && "Missing variable");
+
+ if (Deref || Offset) {
+ // Create a copy of the original DIDescriptor for user variable, prepending
+ // "deref" operation to a list of address elements, as new llvm.dbg.declare
+ // will take a value storing address of the memory for variable, not
+ // alloca itself.
+ SmallVector<uint64_t, 4> NewDIExpr;
+ if (Deref)
+ NewDIExpr.push_back(dwarf::DW_OP_deref);
+ if (Offset > 0) {
+ NewDIExpr.push_back(dwarf::DW_OP_plus);
+ NewDIExpr.push_back(Offset);
+ } else if (Offset < 0) {
+ NewDIExpr.push_back(dwarf::DW_OP_minus);
+ NewDIExpr.push_back(-Offset);
+ }
+ if (DIExpr)
+ NewDIExpr.append(DIExpr->elements_begin(), DIExpr->elements_end());
+ DIExpr = Builder.createExpression(NewDIExpr);
+ }
+
+ // Insert llvm.dbg.declare immediately after the original alloca, and remove
+ // old llvm.dbg.declare.
+ Builder.insertDeclare(NewAddress, DIVar, DIExpr, Loc, InsertBefore);
+ DDI->eraseFromParent();
+ return true;
+}
+
+bool llvm::replaceDbgDeclareForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
+ DIBuilder &Builder, bool Deref, int Offset) {
+ return replaceDbgDeclare(AI, NewAllocaAddress, AI->getNextNode(), Builder,
+ Deref, Offset);
+}
+
+/// changeToUnreachable - Insert an unreachable instruction before the specified
+/// instruction, making it and the rest of the code in the block dead.
+static void changeToUnreachable(Instruction *I, bool UseLLVMTrap) {
+ BasicBlock *BB = I->getParent();
+ // Loop over all of the successors, removing BB's entry from any PHI
+ // nodes.
+ for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
+ (*SI)->removePredecessor(BB);
+
+ // Insert a call to llvm.trap right before this. This turns the undefined
+ // behavior into a hard fail instead of falling through into random code.
+ if (UseLLVMTrap) {
+ Function *TrapFn =
+ Intrinsic::getDeclaration(BB->getParent()->getParent(), Intrinsic::trap);
+ CallInst *CallTrap = CallInst::Create(TrapFn, "", I);
+ CallTrap->setDebugLoc(I->getDebugLoc());
+ }
+ new UnreachableInst(I->getContext(), I);
+
+ // All instructions after this are dead.
+ BasicBlock::iterator BBI = I->getIterator(), BBE = BB->end();
+ while (BBI != BBE) {
+ if (!BBI->use_empty())
+ BBI->replaceAllUsesWith(UndefValue::get(BBI->getType()));
+ BB->getInstList().erase(BBI++);
+ }
+}
+
+/// changeToCall - Convert the specified invoke into a normal call.
+static void changeToCall(InvokeInst *II) {
+ SmallVector<Value*, 8> Args(II->arg_begin(), II->arg_end());
+ SmallVector<OperandBundleDef, 1> OpBundles;
+ II->getOperandBundlesAsDefs(OpBundles);
+ CallInst *NewCall = CallInst::Create(II->getCalledValue(), Args, OpBundles,
+ "", II);
+ NewCall->takeName(II);
+ NewCall->setCallingConv(II->getCallingConv());
+ NewCall->setAttributes(II->getAttributes());
+ NewCall->setDebugLoc(II->getDebugLoc());
+ II->replaceAllUsesWith(NewCall);
+
+ // Follow the call by a branch to the normal destination.
+ BranchInst::Create(II->getNormalDest(), II);
+
+ // Update PHI nodes in the unwind destination
+ II->getUnwindDest()->removePredecessor(II->getParent());
+ II->eraseFromParent();
+}
+
+static bool markAliveBlocks(Function &F,
+ SmallPtrSetImpl<BasicBlock*> &Reachable) {
+
+ SmallVector<BasicBlock*, 128> Worklist;
+ BasicBlock *BB = &F.front();
+ Worklist.push_back(BB);
+ Reachable.insert(BB);
+ bool Changed = false;
+ do {
+ BB = Worklist.pop_back_val();
+
+ // Do a quick scan of the basic block, turning any obviously unreachable
+ // instructions into LLVM unreachable insts. The instruction combining pass
+ // canonicalizes unreachable insts into stores to null or undef.
+ for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E;++BBI){
+ // Assumptions that are known to be false are equivalent to unreachable.
+ // Also, if the condition is undefined, then we make the choice most
+ // beneficial to the optimizer, and choose that to also be unreachable.
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BBI))
+ if (II->getIntrinsicID() == Intrinsic::assume) {
+ bool MakeUnreachable = false;
+ if (isa<UndefValue>(II->getArgOperand(0)))
+ MakeUnreachable = true;
+ else if (ConstantInt *Cond =
+ dyn_cast<ConstantInt>(II->getArgOperand(0)))
+ MakeUnreachable = Cond->isZero();
+
+ if (MakeUnreachable) {
+ // Don't insert a call to llvm.trap right before the unreachable.
+ changeToUnreachable(&*BBI, false);
+ Changed = true;
+ break;
+ }
+ }
+
+ if (CallInst *CI = dyn_cast<CallInst>(BBI)) {
+ if (CI->doesNotReturn()) {
+ // If we found a call to a no-return function, insert an unreachable
+ // instruction after it. Make sure there isn't *already* one there
+ // though.
+ ++BBI;
+ if (!isa<UnreachableInst>(BBI)) {
+ // Don't insert a call to llvm.trap right before the unreachable.
+ changeToUnreachable(&*BBI, false);
+ Changed = true;
+ }
+ break;
+ }
+ }
+
+ // Store to undef and store to null are undefined and used to signal that
+ // they should be changed to unreachable by passes that can't modify the
+ // CFG.
+ if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
+ // Don't touch volatile stores.
+ if (SI->isVolatile()) continue;
+
+ Value *Ptr = SI->getOperand(1);
+
+ if (isa<UndefValue>(Ptr) ||
+ (isa<ConstantPointerNull>(Ptr) &&
+ SI->getPointerAddressSpace() == 0)) {
+ changeToUnreachable(SI, true);
+ Changed = true;
+ break;
+ }
+ }
+ }
+
+ // Turn invokes that call 'nounwind' functions into ordinary calls.
+ if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
+ Value *Callee = II->getCalledValue();
+ if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
+ changeToUnreachable(II, true);
+ Changed = true;
+ } else if (II->doesNotThrow() && canSimplifyInvokeNoUnwind(&F)) {
+ if (II->use_empty() && II->onlyReadsMemory()) {
+ // jump to the normal destination branch.
+ BranchInst::Create(II->getNormalDest(), II);
+ II->getUnwindDest()->removePredecessor(II->getParent());
+ II->eraseFromParent();
+ } else
+ changeToCall(II);
Changed = true;
- break;
}
- // A non-duplicate hash collision.
- DenseMap<PHINode *, PHINode *>::iterator I = CollisionMap.find(OtherPN);
- if (I == CollisionMap.end()) {
- // Set this PHI to be the head of the linked list of colliding PHIs.
- PHINode *Old = Pair.first->second;
- Pair.first->second = PN;
- CollisionMap[PN] = Old;
+ }
+
+ Changed |= ConstantFoldTerminator(BB, true);
+ for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
+ if (Reachable.insert(*SI).second)
+ Worklist.push_back(*SI);
+ } while (!Worklist.empty());
+ return Changed;
+}
+
+void llvm::removeUnwindEdge(BasicBlock *BB) {
+ TerminatorInst *TI = BB->getTerminator();
+
+ if (auto *II = dyn_cast<InvokeInst>(TI)) {
+ changeToCall(II);
+ return;
+ }
+
+ TerminatorInst *NewTI;
+ BasicBlock *UnwindDest;
+
+ if (auto *CRI = dyn_cast<CleanupReturnInst>(TI)) {
+ NewTI = CleanupReturnInst::Create(CRI->getCleanupPad(), nullptr, CRI);
+ UnwindDest = CRI->getUnwindDest();
+ } else if (auto *CEP = dyn_cast<CleanupEndPadInst>(TI)) {
+ NewTI = CleanupEndPadInst::Create(CEP->getCleanupPad(), nullptr, CEP);
+ UnwindDest = CEP->getUnwindDest();
+ } else if (auto *CEP = dyn_cast<CatchEndPadInst>(TI)) {
+ NewTI = CatchEndPadInst::Create(CEP->getContext(), nullptr, CEP);
+ UnwindDest = CEP->getUnwindDest();
+ } else if (auto *TPI = dyn_cast<TerminatePadInst>(TI)) {
+ SmallVector<Value *, 3> TerminatePadArgs;
+ for (Value *Operand : TPI->arg_operands())
+ TerminatePadArgs.push_back(Operand);
+ NewTI = TerminatePadInst::Create(TPI->getContext(), nullptr,
+ TerminatePadArgs, TPI);
+ UnwindDest = TPI->getUnwindDest();
+ } else {
+ llvm_unreachable("Could not find unwind successor");
+ }
+
+ NewTI->takeName(TI);
+ NewTI->setDebugLoc(TI->getDebugLoc());
+ UnwindDest->removePredecessor(BB);
+ TI->eraseFromParent();
+}
+
+/// removeUnreachableBlocksFromFn - Remove blocks that are not reachable, even
+/// if they are in a dead cycle. Return true if a change was made, false
+/// otherwise.
+bool llvm::removeUnreachableBlocks(Function &F) {
+ SmallPtrSet<BasicBlock*, 128> Reachable;
+ bool Changed = markAliveBlocks(F, Reachable);
+
+ // If there are unreachable blocks in the CFG...
+ if (Reachable.size() == F.size())
+ return Changed;
+
+ assert(Reachable.size() < F.size());
+ NumRemoved += F.size()-Reachable.size();
+
+ // Loop over all of the basic blocks that are not reachable, dropping all of
+ // their internal references...
+ for (Function::iterator BB = ++F.begin(), E = F.end(); BB != E; ++BB) {
+ if (Reachable.count(&*BB))
+ continue;
+
+ for (succ_iterator SI = succ_begin(&*BB), SE = succ_end(&*BB); SI != SE;
+ ++SI)
+ if (Reachable.count(*SI))
+ (*SI)->removePredecessor(&*BB);
+ BB->dropAllReferences();
+ }
+
+ for (Function::iterator I = ++F.begin(); I != F.end();)
+ if (!Reachable.count(&*I))
+ I = F.getBasicBlockList().erase(I);
+ else
+ ++I;
+
+ return true;
+}
+
+void llvm::combineMetadata(Instruction *K, const Instruction *J,
+ ArrayRef<unsigned> KnownIDs) {
+ SmallVector<std::pair<unsigned, MDNode *>, 4> Metadata;
+ K->dropUnknownNonDebugMetadata(KnownIDs);
+ K->getAllMetadataOtherThanDebugLoc(Metadata);
+ for (unsigned i = 0, n = Metadata.size(); i < n; ++i) {
+ unsigned Kind = Metadata[i].first;
+ MDNode *JMD = J->getMetadata(Kind);
+ MDNode *KMD = Metadata[i].second;
+
+ switch (Kind) {
+ default:
+ K->setMetadata(Kind, nullptr); // Remove unknown metadata
+ break;
+ case LLVMContext::MD_dbg:
+ llvm_unreachable("getAllMetadataOtherThanDebugLoc returned a MD_dbg");
+ case LLVMContext::MD_tbaa:
+ K->setMetadata(Kind, MDNode::getMostGenericTBAA(JMD, KMD));
+ break;
+ case LLVMContext::MD_alias_scope:
+ K->setMetadata(Kind, MDNode::getMostGenericAliasScope(JMD, KMD));
+ break;
+ case LLVMContext::MD_noalias:
+ K->setMetadata(Kind, MDNode::intersect(JMD, KMD));
+ break;
+ case LLVMContext::MD_range:
+ K->setMetadata(Kind, MDNode::getMostGenericRange(JMD, KMD));
+ break;
+ case LLVMContext::MD_fpmath:
+ K->setMetadata(Kind, MDNode::getMostGenericFPMath(JMD, KMD));
+ break;
+ case LLVMContext::MD_invariant_load:
+ // Only set the !invariant.load if it is present in both instructions.
+ K->setMetadata(Kind, JMD);
+ break;
+ case LLVMContext::MD_nonnull:
+ // Only set the !nonnull if it is present in both instructions.
+ K->setMetadata(Kind, JMD);
+ break;
+ case LLVMContext::MD_invariant_group:
+ // Preserve !invariant.group in K.
+ break;
+ case LLVMContext::MD_align:
+ K->setMetadata(Kind,
+ MDNode::getMostGenericAlignmentOrDereferenceable(JMD, KMD));
+ break;
+ case LLVMContext::MD_dereferenceable:
+ case LLVMContext::MD_dereferenceable_or_null:
+ K->setMetadata(Kind,
+ MDNode::getMostGenericAlignmentOrDereferenceable(JMD, KMD));
break;
- }
- // Procede to the next PHI in the list.
- OtherPN = I->second;
}
}
+ // Set !invariant.group from J if J has it. If both instructions have it
+ // then we will just pick it from J - even when they are different.
+ // Also make sure that K is load or store - f.e. combining bitcast with load
+ // could produce bitcast with invariant.group metadata, which is invalid.
+ // FIXME: we should try to preserve both invariant.group md if they are
+ // different, but right now instruction can only have one invariant.group.
+ if (auto *JMD = J->getMetadata(LLVMContext::MD_invariant_group))
+ if (isa<LoadInst>(K) || isa<StoreInst>(K))
+ K->setMetadata(LLVMContext::MD_invariant_group, JMD);
+}
- return Changed;
+unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
+ DominatorTree &DT,
+ const BasicBlockEdge &Root) {
+ assert(From->getType() == To->getType());
+
+ unsigned Count = 0;
+ for (Value::use_iterator UI = From->use_begin(), UE = From->use_end();
+ UI != UE; ) {
+ Use &U = *UI++;
+ if (DT.dominates(Root, U)) {
+ U.set(To);
+ DEBUG(dbgs() << "Replace dominated use of '"
+ << From->getName() << "' as "
+ << *To << " in " << *U << "\n");
+ ++Count;
+ }
+ }
+ return Count;
+}
+
+unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
+ DominatorTree &DT,
+ const BasicBlock *BB) {
+ assert(From->getType() == To->getType());
+
+ unsigned Count = 0;
+ for (Value::use_iterator UI = From->use_begin(), UE = From->use_end();
+ UI != UE;) {
+ Use &U = *UI++;
+ auto *I = cast<Instruction>(U.getUser());
+ if (DT.dominates(BB, I->getParent())) {
+ U.set(To);
+ DEBUG(dbgs() << "Replace dominated use of '" << From->getName() << "' as "
+ << *To << " in " << *U << "\n");
+ ++Count;
+ }
+ }
+ return Count;
+}
+
+bool llvm::callsGCLeafFunction(ImmutableCallSite CS) {
+ if (isa<IntrinsicInst>(CS.getInstruction()))
+ // Most LLVM intrinsics are things which can never take a safepoint.
+ // As a result, we don't need to have the stack parsable at the
+ // callsite. This is a highly useful optimization since intrinsic
+ // calls are fairly prevalent, particularly in debug builds.
+ return true;
+
+ // Check if the function is specifically marked as a gc leaf function.
+ //
+ // TODO: we should be checking the attributes on the call site as well.
+ if (const Function *F = CS.getCalledFunction())
+ return F->hasFnAttribute("gc-leaf-function");
+
+ return false;
}
projects / oota-llvm.git / blobdiff