#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/Analysis/Dominators.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/MemoryBuiltins.h"
-#include "llvm/Analysis/ProfileInfo.h"
#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/DIBuilder.h"
-#include "llvm/DebugInfo.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/MDBuilder.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Operator.h"
-#include "llvm/Support/CFG.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.
//
// 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 (i.getCaseSuccessor() == DefaultDest) {
- MDNode* MD = SI->getMetadata(LLVMContext::MD_prof);
- // MD should have 2 + NumCases operands.
- if (MD && MD->getNumOperands() == 2 + SI->getNumCases()) {
+ 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 = dyn_cast<ConstantInt>(MD->getOperand(MD_i));
+ ConstantInt *CI =
+ mdconst::dyn_extract<ConstantInt>(MD->getOperand(MD_i));
assert(CI);
Weights.push_back(CI->getValue().getZExtValue());
}
// 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 (i.getCaseSuccessor() != TheOnlyDest) TheOnlyDest = 0;
+ if (i.getCaseSuccessor() != TheOnlyDest) TheOnlyDest = nullptr;
}
if (CI && !TheOnlyDest) {
// 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);
}
// Otherwise, we can fold this switch into a conditional branch
// instruction if it has only one non-default destination.
SwitchInst::CaseIt FirstCase = SI->case_begin();
- IntegersSubset& Case = FirstCase.getCaseValueEx();
- if (Case.isSingleNumber()) {
- // FIXME: Currently work with ConstantInt based numbers.
- Value *Cond = Builder.CreateICmpEQ(SI->getCondition(),
- Case.getSingleNumber(0).toConstantInt(),
- "cond");
-
- // Insert the new branch.
- BranchInst *NewBr = Builder.CreateCondBr(Cond,
- FirstCase.getCaseSuccessor(),
- SI->getDefaultDest());
- MDNode* MD = SI->getMetadata(LLVMContext::MD_prof);
- if (MD && MD->getNumOperands() == 3) {
- ConstantInt *SICase = dyn_cast<ConstantInt>(MD->getOperand(2));
- ConstantInt *SIDef = dyn_cast<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()));
- }
+ Value *Cond = Builder.CreateICmpEQ(SI->getCondition(),
+ FirstCase.getCaseValue(), "cond");
- // Delete the old switch.
- SI->eraseFromParent();
- return true;
+ // Insert the new branch.
+ 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()));
}
+
+ // Delete the old switch.
+ SI->eraseFromParent();
+ return true;
}
return false;
}
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());
}
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;
// 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;
/// true when there are no uses or multiple uses that all refer to the same
/// value.
static bool areAllUsesEqual(Instruction *I) {
- Value::use_iterator UI = I->use_begin();
- Value::use_iterator UE = I->use_end();
+ Value::user_iterator UI = I->user_begin();
+ Value::user_iterator UE = I->user_end();
if (UI == UE)
return true;
const TargetLibraryInfo *TLI) {
SmallPtrSet<Instruction*, 4> Visited;
for (Instruction *I = PN; areAllUsesEqual(I) && !I->mayHaveSideEffects();
- I = cast<Instruction>(*I->use_begin())) {
+ I = cast<Instruction>(*I->user_begin())) {
if (I->use_empty())
return RecursivelyDeleteTriviallyDeadInstructions(I, TLI);
// If we find an instruction more than once, we're on a cycle that
// won't prove fruitful.
- if (!Visited.insert(I)) {
+ 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);
Instruction *Inst = BI++;
WeakVH BIHandle(BI);
- if (recursivelySimplifyInstruction(Inst, TD)) {
+ if (recursivelySimplifyInstruction(Inst, TD, TLI)) {
MadeChange = true;
if (BIHandle != BI)
BI = BB->begin();
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 (P) {
- DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>();
- if (DT) {
- BasicBlock *PredBBIDom = DT->getNode(PredBB)->getIDom()->getBlock();
- DT->changeImmediateDominator(DestBB, PredBBIDom);
- DT->eraseNode(PredBB);
- }
- ProfileInfo *PI = P->getAnalysisIfAvailable<ProfileInfo>();
- if (PI) {
- PI->replaceAllUses(PredBB, DestBB);
- PI->removeEdge(ProfileInfo::getEdge(PredBB, DestBB));
+ if (DominatorTreeWrapperPass *DTWP =
+ P->getAnalysisIfAvailable<DominatorTreeWrapperPass>()) {
+ DominatorTree &DT = DTWP->getDomTree();
+ BasicBlock *PredBBIDom = DT.getNode(PredBB)->getIDom()->getBlock();
+ DT.changeImmediateDominator(DestBB, PredBBIDom);
+ DT.eraseNode(PredBB);
}
}
// Nuke BB.
}
/// 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.
///
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;
return PrefAlign;
}
- if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
+ 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 (GV->isDeclaration()) return Align;
+ if (GO->isDeclaration())
+ return Align;
// 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 (GV->isWeakForLinker()) return Align;
+ if (GO->isWeakForLinker())
+ return Align;
- if (GV->getAlignment() >= PrefAlign)
- return GV->getAlignment();
+ 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 (!GV->hasSection() || GV->getAlignment() == 0)
- GV->setAlignment(PrefAlign);
- return GV->getAlignment();
+ if (!GO->hasSection() || GO->getAlignment() == 0)
+ GO->setAlignment(PrefAlign);
+ return GO->getAlignment();
}
return Align;
/// 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 DataLayout *DL,
+ AssumptionCache *AC,
+ const Instruction *CxtI,
+ const DominatorTree *DT) {
assert(V->getType()->isPointerTy() &&
"getOrEnforceKnownAlignment expects a pointer!");
unsigned BitWidth = DL ? DL->getPointerTypeSizeInBits(V->getType()) : 64;
APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
- ComputeMaskedBits(V, KnownZero, KnownOne, DL);
+ computeKnownBits(V, KnownZero, KnownOne, DL, 0, AC, CxtI, DT);
unsigned TrailZ = KnownZero.countTrailingOnes();
// Avoid trouble with ridiculously large TrailZ values, such as
bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
StoreInst *SI, DIBuilder &Builder) {
DIVariable DIVar(DDI->getVariable());
+ DIExpression DIExpr(DDI->getExpression());
assert((!DIVar || DIVar.isVariable()) &&
"Variable in DbgDeclareInst should be either null or a DIVariable.");
if (!DIVar)
if (LdStHasDebugValue(DIVar, SI))
return true;
- Instruction *DbgVal = NULL;
+ Instruction *DbgVal = nullptr;
// If an argument is zero extended then use argument directly. The ZExt
// may be zapped by an optimization pass in future.
- Argument *ExtendedArg = NULL;
+ 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)
- DbgVal = Builder.insertDbgValueIntrinsic(ExtendedArg, 0, DIVar, SI);
- else
- DbgVal = Builder.insertDbgValueIntrinsic(SI->getOperand(0), 0, DIVar, SI);
-
- // Propagate any debug metadata from the store onto the dbg.value.
- DebugLoc SIDL = SI->getDebugLoc();
- if (!SIDL.isUnknown())
- DbgVal->setDebugLoc(SIDL);
- // Otherwise propagate debug metadata from dbg.declare.
+ DbgVal = Builder.insertDbgValueIntrinsic(ExtendedArg, 0, DIVar, DIExpr, SI);
else
- DbgVal->setDebugLoc(DDI->getDebugLoc());
+ DbgVal = Builder.insertDbgValueIntrinsic(SI->getOperand(0), 0, DIVar,
+ DIExpr, SI);
+ DbgVal->setDebugLoc(DDI->getDebugLoc());
return true;
}
bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
LoadInst *LI, DIBuilder &Builder) {
DIVariable DIVar(DDI->getVariable());
+ DIExpression DIExpr(DDI->getExpression());
assert((!DIVar || DIVar.isVariable()) &&
"Variable in DbgDeclareInst should be either null or a DIVariable.");
if (!DIVar)
return true;
Instruction *DbgVal =
- Builder.insertDbgValueIntrinsic(LI->getOperand(0), 0,
- DIVar, LI);
-
- // Propagate any debug metadata from the store onto the dbg.value.
- DebugLoc LIDL = LI->getDebugLoc();
- if (!LIDL.isUnknown())
- DbgVal->setDebugLoc(LIDL);
- // Otherwise propagate debug metadata from dbg.declare.
- else
- DbgVal->setDebugLoc(DDI->getDebugLoc());
+ Builder.insertDbgValueIntrinsic(LI->getOperand(0), 0, DIVar, DIExpr, LI);
+ DbgVal->setDebugLoc(DDI->getDebugLoc());
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());
+ DIBuilder DIB(*F.getParent(), /*AllowUnresolved*/ false);
SmallVector<DbgDeclareInst *, 4> Dbgs;
- for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
- for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); BI != BE; ++BI) {
- if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(BI))
+ for (auto &FI : F)
+ for (BasicBlock::iterator BI : FI)
+ if (auto DDI = dyn_cast<DbgDeclareInst>(BI))
Dbgs.push_back(DDI);
- }
+
if (Dbgs.empty())
return false;
- for (SmallVectorImpl<DbgDeclareInst *>::iterator I = Dbgs.begin(),
- E = Dbgs.end(); I != E; ++I) {
- DbgDeclareInst *DDI = *I;
- if (AllocaInst *AI = dyn_cast_or_null<AllocaInst>(DDI->getAddress())) {
- // We only remove the dbg.declare intrinsic if all uses are
- // converted to dbg.value intrinsics.
- bool RemoveDDI = true;
- for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
- UI != E; ++UI)
- if (StoreInst *SI = dyn_cast<StoreInst>(*UI))
+ 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>(*UI))
+ else if (LoadInst *LI = dyn_cast<LoadInst>(U))
ConvertDebugDeclareToDebugValue(DDI, LI, DIB);
- else
- RemoveDDI = false;
- if (RemoveDDI)
- DDI->eraseFromParent();
+ 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.
+ auto DbgVal = DIB.insertDbgValueIntrinsic(
+ AI, 0, DIVariable(DDI->getVariable()),
+ DIExpression(DDI->getExpression()), CI);
+ DbgVal->setDebugLoc(DDI->getDebugLoc());
+ }
+ DDI->eraseFromParent();
}
}
return true;
/// FindAllocaDbgDeclare - Finds the llvm.dbg.declare intrinsic describing the
/// alloca 'V', if any.
DbgDeclareInst *llvm::FindAllocaDbgDeclare(Value *V) {
- if (MDNode *DebugNode = MDNode::getIfExists(V->getContext(), V))
- for (Value::use_iterator UI = DebugNode->use_begin(),
- E = DebugNode->use_end(); UI != E; ++UI)
- if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(*UI))
- return DDI;
+ 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 0;
+ return nullptr;
}
bool llvm::replaceDbgDeclareForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
if (!DDI)
return false;
DIVariable DIVar(DDI->getVariable());
+ DIExpression DIExpr(DDI->getExpression());
assert((!DIVar || DIVar.isVariable()) &&
"Variable in DbgDeclareInst should be either null or a DIVariable.");
if (!DIVar)
return false;
- // Create a copy of the original DIDescriptor for user variable, appending
+ // 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.
- Type *Int64Ty = Type::getInt64Ty(AI->getContext());
- SmallVector<Value*, 4> NewDIVarAddress;
- if (DIVar.hasComplexAddress()) {
- for (unsigned i = 0, n = DIVar.getNumAddrElements(); i < n; ++i) {
- NewDIVarAddress.push_back(
- ConstantInt::get(Int64Ty, DIVar.getAddrElement(i)));
- }
- }
- NewDIVarAddress.push_back(ConstantInt::get(Int64Ty, DIBuilder::OpDeref));
- DIVariable NewDIVar = Builder.createComplexVariable(
- DIVar.getTag(), DIVar.getContext(), DIVar.getName(),
- DIVar.getFile(), DIVar.getLineNumber(), DIVar.getType(),
- NewDIVarAddress, DIVar.getArgNumber());
+ SmallVector<int64_t, 4> NewDIExpr;
+ NewDIExpr.push_back(dwarf::DW_OP_deref);
+ if (DIExpr)
+ for (unsigned i = 0, n = DIExpr.getNumElements(); i < n; ++i)
+ NewDIExpr.push_back(DIExpr.getElement(i));
// Insert llvm.dbg.declare in the same basic block as the original alloca,
// and remove old llvm.dbg.declare.
BasicBlock *BB = AI->getParent();
- Builder.insertDeclare(NewAllocaAddress, NewDIVar, BB);
+ Builder.insertDeclare(NewAllocaAddress, DIVar,
+ Builder.createExpression(NewDIExpr), BB);
DDI->eraseFromParent();
return true;
}
-bool llvm::removeUnreachableBlocks(Function &F) {
- SmallPtrSet<BasicBlock*, 16> Reachable;
+/// 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, 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->op_begin(), II->op_end() - 3);
+ CallInst *NewCall = CallInst::Create(II->getCalledValue(), Args, "", 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(BasicBlock *BB,
+ SmallPtrSetImpl<BasicBlock*> &Reachable) {
+
SmallVector<BasicBlock*, 128> Worklist;
- Worklist.push_back(&F.getEntryBlock());
- Reachable.insert(&F.getEntryBlock());
+ Worklist.push_back(BB);
+ Reachable.insert(BB);
+ bool Changed = false;
do {
- BasicBlock *BB = Worklist.pop_back_val();
+ 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()) {
+ 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;
+ }
+ }
+
+ Changed |= ConstantFoldTerminator(BB, true);
for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
- if (Reachable.insert(*SI))
+ if (Reachable.insert(*SI).second)
Worklist.push_back(*SI);
} while (!Worklist.empty());
+ return Changed;
+}
+
+/// 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.begin(), Reachable);
+ // If there are unreachable blocks in the CFG...
if (Reachable.size() == F.size())
- return false;
+ return Changed;
assert(Reachable.size() < F.size());
- for (Function::iterator I = llvm::next(F.begin()), E = F.end(); I != E; ++I) {
- if (Reachable.count(I))
+ 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(I), SE = succ_end(I); SI != SE; ++SI)
+ for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
if (Reachable.count(*SI))
- (*SI)->removePredecessor(I);
- I->dropAllReferences();
+ (*SI)->removePredecessor(BB);
+ BB->dropAllReferences();
}
- for (Function::iterator I = llvm::next(F.begin()), E=F.end(); I != E;)
+ for (Function::iterator I = ++F.begin(); I != F.end();)
if (!Reachable.count(I))
I = F.getBasicBlockList().erase(I);
else
return true;
}
+
+void llvm::combineMetadata(Instruction *K, const Instruction *J, ArrayRef<unsigned> KnownIDs) {
+ SmallVector<std::pair<unsigned, MDNode *>, 4> Metadata;
+ K->dropUnknownMetadata(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:
+ 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;
+ }
+ }
+}