#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Constants.h"
+#include "llvm/DIBuilder.h"
+#include "llvm/DebugInfo.h"
+#include "llvm/DerivedTypes.h"
#include "llvm/GlobalAlias.h"
#include "llvm/GlobalVariable.h"
-#include "llvm/DerivedTypes.h"
+#include "llvm/IRBuilder.h"
#include "llvm/Instructions.h"
-#include "llvm/Intrinsics.h"
#include "llvm/IntrinsicInst.h"
+#include "llvm/Intrinsics.h"
+#include "llvm/Metadata.h"
+#include "llvm/Operator.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/ProfileInfo.h"
-#include "llvm/Target/TargetData.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Support/CFG.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"
+#include "llvm/Target/TargetData.h"
using namespace llvm;
-//===----------------------------------------------------------------------===//
-// Local analysis.
-//
-
-/// getUnderlyingObjectWithOffset - Strip off up to MaxLookup GEPs and
-/// bitcasts to get back to the underlying object being addressed, keeping
-/// track of the offset in bytes from the GEPs relative to the result.
-/// This is closely related to Value::getUnderlyingObject but is located
-/// here to avoid making VMCore depend on TargetData.
-static Value *getUnderlyingObjectWithOffset(Value *V, const TargetData *TD,
- uint64_t &ByteOffset,
- unsigned MaxLookup = 6) {
- if (!isa<PointerType>(V->getType()))
- return V;
- for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) {
- if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
- if (!GEP->hasAllConstantIndices())
- return V;
- SmallVector<Value*, 8> Indices(GEP->op_begin() + 1, GEP->op_end());
- ByteOffset += TD->getIndexedOffset(GEP->getPointerOperandType(),
- &Indices[0], Indices.size());
- V = GEP->getPointerOperand();
- } else if (Operator::getOpcode(V) == Instruction::BitCast) {
- V = cast<Operator>(V)->getOperand(0);
- } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
- if (GA->mayBeOverridden())
- return V;
- V = GA->getAliasee();
- } else {
- return V;
- }
- assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
- }
- return V;
-}
-
-/// isSafeToLoadUnconditionally - Return true if we know that executing a load
-/// from this value cannot trap. If it is not obviously safe to load from the
-/// specified pointer, we do a quick local scan of the basic block containing
-/// ScanFrom, to determine if the address is already accessed.
-bool llvm::isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom,
- const TargetData *TD) {
- uint64_t ByteOffset = 0;
- Value *Base = V;
- if (TD)
- Base = getUnderlyingObjectWithOffset(V, TD, ByteOffset);
-
- const Type *BaseType = 0;
- if (const AllocaInst *AI = dyn_cast<AllocaInst>(Base))
- // If it is an alloca it is always safe to load from.
- BaseType = AI->getAllocatedType();
- else if (const GlobalValue *GV = dyn_cast<GlobalValue>(Base)) {
- // Global variables are safe to load from but their size cannot be
- // guaranteed if they are overridden.
- if (!isa<GlobalAlias>(GV) && !GV->mayBeOverridden())
- BaseType = GV->getType()->getElementType();
- }
-
- if (BaseType) {
- if (!TD)
- return true; // Loading directly from an alloca or global is OK.
- if (BaseType->isSized()) {
- // Check if the load is within the bounds of the underlying object.
- const PointerType *AddrTy = cast<PointerType>(V->getType());
- uint64_t LoadSize = TD->getTypeStoreSize(AddrTy->getElementType());
- if (ByteOffset + LoadSize <= TD->getTypeAllocSize(BaseType))
- return true;
- }
- }
-
- // Otherwise, be a little bit aggressive by scanning the local block where we
- // want to check to see if the pointer is already being loaded or stored
- // from/to. If so, the previous load or store would have already trapped,
- // so there is no harm doing an extra load (also, CSE will later eliminate
- // the load entirely).
- BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
-
- while (BBI != E) {
- --BBI;
-
- // If we see a free or a call which may write to memory (i.e. which might do
- // a free) the pointer could be marked invalid.
- if (isa<CallInst>(BBI) && BBI->mayWriteToMemory() &&
- !isa<DbgInfoIntrinsic>(BBI))
- return false;
-
- if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
- if (LI->getOperand(0) == V) return true;
- } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
- if (SI->getOperand(1) == V) return true;
- }
- }
- return false;
-}
-
-
//===----------------------------------------------------------------------===//
// 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;
}
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 we are switching on a constant, we can convert the switch into a
// single branch instruction!
ConstantInt *CI = dyn_cast<ConstantInt>(SI->getCondition());
- BasicBlock *TheOnlyDest = SI->getSuccessor(0); // The default dest
+ BasicBlock *TheOnlyDest = SI->getDefaultDest();
BasicBlock *DefaultDest = TheOnlyDest;
- assert(TheOnlyDest == SI->getDefaultDest() &&
- "Default destination is not successor #0?");
// 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) {
// 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 = 0;
}
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...
}
// 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");
- // Insert the new branch.
- BranchInst::Create(SI->getSuccessor(1), SI->getSuccessor(0), Cond, SI);
-
- // Delete the old switch.
- SI->eraseFromParent();
- return true;
+ 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.
+ Builder.CreateCondBr(Cond, FirstCase.getCaseSuccessor(),
+ SI->getDefaultDest());
+
+ // Delete the old switch.
+ SI->eraseFromParent();
+ return true;
+ }
}
return false;
}
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)
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
/// 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 instruction removed by anything this general.
+ if (isa<LandingPadInst>(I))
+ return false;
- // Likewise for memory use markers.
- if (isa<MemoryUseIntrinsic>(I)) 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));
+ }
+
+ 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;
// 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);
}
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::use_iterator UI = I->use_begin();
+ Value::use_iterator UE = I->use_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;
-
- 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
+/// 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->use_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 (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)) {
+ // Break the cycle and delete the instruction and its operands.
+ I->replaceAllUsesWith(UndefValue::get(I->getType()));
+ (void)RecursivelyDeleteTriviallyDeadInstructions(I, TLI);
+ 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 TargetData *TD,
+ const TargetLibraryInfo *TLI) {
bool MadeChange = false;
- for (BasicBlock::iterator BI = BB->begin(), E = BB->end(); BI != E; ) {
+
+#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->end());
+#endif
+
+ for (BasicBlock::iterator BI = BB->begin(), E = --BB->end(); BI != E; ) {
+ assert(!BI->isTerminator());
Instruction *Inst = BI++;
-
- if (Value *V = SimplifyInstruction(Inst, TD)) {
- WeakVH BIHandle(BI);
- ReplaceAndSimplifyAllUses(Inst, V, TD);
+
+ WeakVH BIHandle(BI);
+ if (recursivelySimplifyInstruction(Inst, TD)) {
MadeChange = true;
- if (BIHandle == 0)
+ if (BIHandle != BI)
BI = BB->begin();
continue;
}
-
- MadeChange |= RecursivelyDeleteTriviallyDeadInstructions(Inst);
+
+ MadeChange |= RecursivelyDeleteTriviallyDeadInstructions(Inst, TLI);
+ if (BIHandle != BI)
+ BI = BB->begin();
}
return MadeChange;
}
WeakVH PhiIt = &BB->front();
while (PHINode *PN = dyn_cast<PHINode>(PhiIt)) {
PhiIt = &*++BasicBlock::iterator(cast<Instruction>(PhiIt));
-
- Value *PNV = PN->hasConstantValue();
- if (PNV == 0) 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 && "hasConstantValue broken");
-
- ReplaceAndSimplifyAllUses(PN, PNV, TD);
-
+ Value *OldPhiIt = PhiIt;
+
+ if (!recursivelySimplifyInstruction(PN, TD))
+ continue;
+
// 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.
- if (PhiIt == 0) PhiIt = &BB->front();
+ if (PhiIt != OldPhiIt) PhiIt = &BB->front();
}
}
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.
+ if (DestBB->hasAddressTaken()) {
+ BlockAddress *BA = BlockAddress::get(DestBB);
+ Constant *Replacement =
+ ConstantInt::get(llvm::Type::getInt32Ty(BA->getContext()), 1);
+ BA->replaceAllUsesWith(ConstantExpr::getIntToPtr(Replacement,
+ BA->getType()));
+ BA->destroyConstant();
+ }
// Anything that branched to PredBB now branches to DestBB.
PredBB->replaceAllUsesWith(DestBB);
+ // Splice all the instructions from PredBB to DestBB.
+ PredBB->getTerminator()->eraseFromParent();
+ DestBB->getInstList().splice(DestBB->begin(), PredBB->getInstList());
+
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);
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)
- if (BBPreds.count(*PI))
- CommonPreds.insert(*PI);
-
- // Shortcut, if there are no common predecessors, merging is always safe
- if (CommonPreds.empty())
- return true;
-
+ SmallPtrSet<BasicBlock*, 16> BBPreds(pred_begin(BB), pred_end(BB));
+
// 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)) {
+ for (unsigned PI = 0, PE = PN->getNumIncomingValues(); PI != PE; ++PI) {
+ BasicBlock *IBB = PN->getIncomingBlock(PI);
+ if (BBPreds.count(IBB) &&
+ 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)) {
+ BasicBlock *IBB = PN->getIncomingBlock(PI);
+ if (BBPreds.count(IBB) && 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;
}
}
/// 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;
}
}
- 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(), 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();
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
// 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;
+ // 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.
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));
}
+ for (PHINode::block_iterator I = PN->block_begin(), E = PN->block_end();
+ I != E; ++I) {
+ Hash ^= reinterpret_cast<uintptr_t>(static_cast<BasicBlock *>(*I));
+ Hash = (Hash << 7) | (Hash >> (sizeof(uintptr_t) * CHAR_BIT - 7));
+ }
+ // Avoid colliding with the DenseMap sentinels ~0 and ~0-1.
+ Hash >>= 1;
// 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));
CollisionMap[PN] = Old;
break;
}
- // Procede to the next PHI in the list.
+ // Proceed to the next PHI in the list.
OtherPN = I->second;
}
}
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 TargetData *TD) {
+ 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 (TD && TD->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 (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
+ // If there is a large requested alignment and we can, bump up the alignment
+ // of the global.
+ if (GV->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 (GV->getAlignment() >= PrefAlign)
+ return GV->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();
+ }
+
+ 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 TargetData *TD) {
+ assert(V->getType()->isPointerTy() &&
+ "getOrEnforceKnownAlignment expects a pointer!");
+ unsigned BitWidth = TD ? TD->getPointerSizeInBits() : 64;
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ ComputeMaskedBits(V, KnownZero, KnownOne, TD);
+ unsigned TrailZ = KnownZero.countTrailingOnes();
+
+ // Avoid trouble with rediculously 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, TD);
+
+ // We don't need to make any adjustment.
+ return Align;
+}
+
+///===---------------------------------------------------------------------===//
+/// Dbg Intrinsic utilities
+///
+
+/// Inserts a llvm.dbg.value instrinsic before the stores to an alloca'd value
+/// that has an associated llvm.dbg.decl intrinsic.
+bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+ StoreInst *SI, DIBuilder &Builder) {
+ DIVariable DIVar(DDI->getVariable());
+ if (!DIVar.Verify())
+ return false;
+
+ Instruction *DbgVal = NULL;
+ // If an argument is zero extended then use argument directly. The ZExt
+ // may be zapped by an optimization pass in future.
+ Argument *ExtendedArg = NULL;
+ 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.
+ else
+ DbgVal->setDebugLoc(DDI->getDebugLoc());
+ return true;
+}
+
+/// Inserts a llvm.dbg.value instrinsic before the stores to an alloca'd value
+/// that has an associated llvm.dbg.decl intrinsic.
+bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+ LoadInst *LI, DIBuilder &Builder) {
+ DIVariable DIVar(DDI->getVariable());
+ if (!DIVar.Verify())
+ return false;
+
+ 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());
+ return true;
+}
+
+/// LowerDbgDeclare - Lowers llvm.dbg.declare intrinsics into appropriate set
+/// of llvm.dbg.value intrinsics.
+bool llvm::LowerDbgDeclare(Function &F) {
+ DIBuilder DIB(*F.getParent());
+ 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))
+ Dbgs.push_back(DDI);
+ }
+ if (Dbgs.empty())
+ return false;
+
+ for (SmallVector<DbgDeclareInst *, 4>::iterator I = Dbgs.begin(),
+ E = Dbgs.end(); I != E; ++I) {
+ DbgDeclareInst *DDI = *I;
+ if (AllocaInst *AI = dyn_cast_or_null<AllocaInst>(DDI->getAddress())) {
+ 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))
+ ConvertDebugDeclareToDebugValue(DDI, SI, DIB);
+ else if (LoadInst *LI = dyn_cast<LoadInst>(*UI))
+ ConvertDebugDeclareToDebugValue(DDI, LI, DIB);
+ else
+ RemoveDDI = false;
+ if (RemoveDDI)
+ 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;
+
+ return 0;
+}
projects / oota-llvm.git / blobdiff