mirror of
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Revert all my SSAUpdater patches. The PHI placement algorithm is not correct
(what was I thinking?) and there's also a problem with LCSSA. I'll try again later with fixes. --- Reverse-merging r100263 into '.': U lib/Transforms/Utils/SSAUpdater.cpp --- Reverse-merging r100177 into '.': G lib/Transforms/Utils/SSAUpdater.cpp --- Reverse-merging r100148 into '.': G lib/Transforms/Utils/SSAUpdater.cpp --- Reverse-merging r100147 into '.': U include/llvm/Transforms/Utils/SSAUpdater.h G lib/Transforms/Utils/SSAUpdater.cpp --- Reverse-merging r100131 into '.': G include/llvm/Transforms/Utils/SSAUpdater.h G lib/Transforms/Utils/SSAUpdater.cpp --- Reverse-merging r100130 into '.': G lib/Transforms/Utils/SSAUpdater.cpp --- Reverse-merging r100126 into '.': G include/llvm/Transforms/Utils/SSAUpdater.h G lib/Transforms/Utils/SSAUpdater.cpp --- Reverse-merging r100050 into '.': D test/Transforms/GVN/2010-03-31-RedundantPHIs.ll --- Reverse-merging r100047 into '.': G include/llvm/Transforms/Utils/SSAUpdater.h G lib/Transforms/Utils/SSAUpdater.cpp llvm-svn: 100264
This commit is contained in:
Bob Wilson
parent
71b0b33e05
commit
5a3200f750
@ -27,28 +27,22 @@ namespace llvm {
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/// transformation wants to rewrite a set of uses of one value with uses of a
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/// set of values.
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class SSAUpdater {
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public:
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class BBInfo;
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private:
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/// AvailableVals - This keeps track of which value to use on a per-block
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/// basis. When we insert PHI nodes, we keep track of them here.
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//typedef DenseMap<BasicBlock*, Value*> AvailableValsTy;
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/// basis. When we insert PHI nodes, we keep track of them here. We use
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/// TrackingVH's for the value of the map because we RAUW PHI nodes when we
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/// eliminate them, and want the TrackingVH's to track this.
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//typedef DenseMap<BasicBlock*, TrackingVH<Value> > AvailableValsTy;
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void *AV;
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/// PrototypeValue is an arbitrary representative value, which we derive names
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/// and a type for PHI nodes.
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Value *PrototypeValue;
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/// BBMap - The GetValueAtEndOfBlock method maintains this mapping from
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/// basic blocks to BBInfo structures.
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/// typedef DenseMap<BasicBlock*, BBInfo*> BBMapTy;
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void *BM;
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/// Allocator - The GetValueAtEndOfBlock method uses this BumpPtrAllocator to
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/// hold its internal data. The allocator and its storage is created and
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/// discarded for each invocation of GetValueAtEndOfBlock.
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void *BPA;
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/// IncomingPredInfo - We use this as scratch space when doing our recursive
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/// walk. This should only be used in GetValueInBlockInternal, normally it
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/// should be empty.
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//std::vector<std::pair<BasicBlock*, TrackingVH<Value> > > IncomingPredInfo;
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void *IPI;
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/// InsertedPHIs - If this is non-null, the SSAUpdater adds all PHI nodes that
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/// it creates to the vector.
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@ -105,14 +99,6 @@ public:
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private:
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Value *GetValueAtEndOfBlockInternal(BasicBlock *BB);
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void FindPHIPlacement(BasicBlock *BB, BBInfo *Info, bool &Changed,
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unsigned Counter);
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void FindAvailableVal(BasicBlock *BB, BBInfo *Info, unsigned Counter);
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void FindExistingPHI(BasicBlock *BB);
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bool CheckIfPHIMatches(PHINode *PHI);
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void RecordMatchingPHI(PHINode *PHI);
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void ClearPHITags(PHINode *PHI);
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void operator=(const SSAUpdater&); // DO NOT IMPLEMENT
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SSAUpdater(const SSAUpdater&); // DO NOT IMPLEMENT
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};
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@ -11,86 +11,34 @@
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "ssaupdater"
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#include "llvm/Transforms/Utils/SSAUpdater.h"
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#include "llvm/Instructions.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/Support/AlignOf.h"
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#include "llvm/Support/Allocator.h"
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#include "llvm/Support/CFG.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ValueHandle.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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/// BBInfo - Per-basic block information used internally by SSAUpdater.
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/// The predecessors of each block are cached here since pred_iterator is
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/// slow and we need to iterate over the blocks at least a few times.
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class SSAUpdater::BBInfo {
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public:
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Value *AvailableVal; // Value to use in this block.
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BasicBlock *DefBB; // Block that defines the available value.
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unsigned NumPreds; // Number of predecessor blocks.
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BasicBlock **Preds; // Array[NumPreds] of predecessor blocks.
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unsigned Counter; // Marker to identify blocks already visited.
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PHINode *PHITag; // Marker for existing PHIs that match.
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typedef DenseMap<BasicBlock*, TrackingVH<Value> > AvailableValsTy;
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typedef std::vector<std::pair<BasicBlock*, TrackingVH<Value> > >
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IncomingPredInfoTy;
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BBInfo(BasicBlock *BB, Value *V, BumpPtrAllocator *Allocator);
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};
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typedef DenseMap<BasicBlock*, SSAUpdater::BBInfo*> BBMapTy;
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SSAUpdater::BBInfo::BBInfo(BasicBlock *BB, Value *V,
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BumpPtrAllocator *Allocator)
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: AvailableVal(V), DefBB(0), NumPreds(0), Preds(0), Counter(0), PHITag(0) {
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// If this block has a known value, don't bother finding its predecessors.
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if (V) {
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DefBB = BB;
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return;
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}
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// We can get our predecessor info by walking the pred_iterator list, but it
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// is relatively slow. If we already have PHI nodes in this block, walk one
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// of them to get the predecessor list instead.
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if (PHINode *SomePhi = dyn_cast<PHINode>(BB->begin())) {
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NumPreds = SomePhi->getNumIncomingValues();
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Preds = static_cast<BasicBlock**>
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(Allocator->Allocate(NumPreds * sizeof(BasicBlock*),
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AlignOf<BasicBlock*>::Alignment));
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for (unsigned pi = 0; pi != NumPreds; ++pi)
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Preds[pi] = SomePhi->getIncomingBlock(pi);
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return;
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}
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// Stash the predecessors in a temporary vector until we know how much space
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// to allocate for them.
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SmallVector<BasicBlock*, 10> TmpPreds;
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for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
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TmpPreds.push_back(*PI);
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++NumPreds;
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}
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Preds = static_cast<BasicBlock**>
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(Allocator->Allocate(NumPreds * sizeof(BasicBlock*),
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AlignOf<BasicBlock*>::Alignment));
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memcpy(Preds, TmpPreds.data(), NumPreds * sizeof(BasicBlock*));
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}
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typedef DenseMap<BasicBlock*, Value*> AvailableValsTy;
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static AvailableValsTy &getAvailableVals(void *AV) {
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return *static_cast<AvailableValsTy*>(AV);
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}
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static BBMapTy *getBBMap(void *BM) {
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return static_cast<BBMapTy*>(BM);
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static IncomingPredInfoTy &getIncomingPredInfo(void *IPI) {
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return *static_cast<IncomingPredInfoTy*>(IPI);
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}
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static BumpPtrAllocator *getAllocator(void *BPA) {
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return static_cast<BumpPtrAllocator*>(BPA);
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}
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SSAUpdater::SSAUpdater(SmallVectorImpl<PHINode*> *NewPHI)
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: AV(0), PrototypeValue(0), BM(0), BPA(0), InsertedPHIs(NewPHI) {}
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: AV(0), PrototypeValue(0), IPI(0), InsertedPHIs(NewPHI) {}
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SSAUpdater::~SSAUpdater() {
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delete &getAvailableVals(AV);
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delete &getIncomingPredInfo(IPI);
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}
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/// Initialize - Reset this object to get ready for a new set of SSA
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@ -100,6 +48,11 @@ void SSAUpdater::Initialize(Value *ProtoValue) {
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AV = new AvailableValsTy();
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else
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getAvailableVals(AV).clear();
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if (IPI == 0)
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IPI = new IncomingPredInfoTy();
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else
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getIncomingPredInfo(IPI).clear();
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PrototypeValue = ProtoValue;
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}
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@ -120,7 +73,7 @@ void SSAUpdater::AddAvailableValue(BasicBlock *BB, Value *V) {
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/// IsEquivalentPHI - Check if PHI has the same incoming value as specified
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/// in ValueMapping for each predecessor block.
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static bool IsEquivalentPHI(PHINode *PHI,
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static bool IsEquivalentPHI(PHINode *PHI,
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DenseMap<BasicBlock*, Value*> &ValueMapping) {
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unsigned PHINumValues = PHI->getNumIncomingValues();
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if (PHINumValues != ValueMapping.size())
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@ -136,12 +89,38 @@ static bool IsEquivalentPHI(PHINode *PHI,
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return true;
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}
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/// GetExistingPHI - Check if BB already contains a phi node that is equivalent
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/// to the specified mapping from predecessor blocks to incoming values.
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static Value *GetExistingPHI(BasicBlock *BB,
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DenseMap<BasicBlock*, Value*> &ValueMapping) {
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PHINode *SomePHI;
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for (BasicBlock::iterator It = BB->begin();
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(SomePHI = dyn_cast<PHINode>(It)); ++It) {
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if (IsEquivalentPHI(SomePHI, ValueMapping))
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return SomePHI;
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}
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return 0;
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}
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/// GetExistingPHI - Check if BB already contains an equivalent phi node.
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/// The InputIt type must be an iterator over std::pair<BasicBlock*, Value*>
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/// objects that specify the mapping from predecessor blocks to incoming values.
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template<typename InputIt>
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static Value *GetExistingPHI(BasicBlock *BB, const InputIt &I,
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const InputIt &E) {
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// Avoid create the mapping if BB has no phi nodes at all.
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if (!isa<PHINode>(BB->begin()))
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return 0;
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DenseMap<BasicBlock*, Value*> ValueMapping(I, E);
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return GetExistingPHI(BB, ValueMapping);
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}
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/// GetValueAtEndOfBlock - Construct SSA form, materializing a value that is
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/// live at the end of the specified block.
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Value *SSAUpdater::GetValueAtEndOfBlock(BasicBlock *BB) {
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assert(BM == 0 && BPA == 0 && "Unexpected Internal State");
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assert(getIncomingPredInfo(IPI).empty() && "Unexpected Internal State");
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Value *Res = GetValueAtEndOfBlockInternal(BB);
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assert(BM == 0 && BPA == 0 && "Unexpected Internal State");
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assert(getIncomingPredInfo(IPI).empty() && "Unexpected Internal State");
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return Res;
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}
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@ -167,7 +146,7 @@ Value *SSAUpdater::GetValueAtEndOfBlock(BasicBlock *BB) {
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Value *SSAUpdater::GetValueInMiddleOfBlock(BasicBlock *BB) {
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// If there is no definition of the renamed variable in this block, just use
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// GetValueAtEndOfBlock to do our work.
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if (!HasValueForBlock(BB))
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if (!getAvailableVals(AV).count(BB))
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return GetValueAtEndOfBlock(BB);
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// Otherwise, we have the hard case. Get the live-in values for each
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@ -214,18 +193,10 @@ Value *SSAUpdater::GetValueInMiddleOfBlock(BasicBlock *BB) {
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if (SingularValue != 0)
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return SingularValue;
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// Otherwise, we do need a PHI: check to see if we already have one available
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// in this block that produces the right value.
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if (isa<PHINode>(BB->begin())) {
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DenseMap<BasicBlock*, Value*> ValueMapping(PredValues.begin(),
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PredValues.end());
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PHINode *SomePHI;
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for (BasicBlock::iterator It = BB->begin();
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(SomePHI = dyn_cast<PHINode>(It)); ++It) {
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if (IsEquivalentPHI(SomePHI, ValueMapping))
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return SomePHI;
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}
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}
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// Otherwise, we do need a PHI.
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if (Value *ExistingPHI = GetExistingPHI(BB, PredValues.begin(),
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PredValues.end()))
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return ExistingPHI;
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// Ok, we have no way out, insert a new one now.
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PHINode *InsertedPHI = PHINode::Create(PrototypeValue->getType(),
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@ -255,7 +226,7 @@ Value *SSAUpdater::GetValueInMiddleOfBlock(BasicBlock *BB) {
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/// which use their value in the corresponding predecessor.
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void SSAUpdater::RewriteUse(Use &U) {
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Instruction *User = cast<Instruction>(U.getUser());
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Value *V;
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if (PHINode *UserPN = dyn_cast<PHINode>(User))
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V = GetValueAtEndOfBlock(UserPN->getIncomingBlock(U));
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@ -265,264 +236,161 @@ void SSAUpdater::RewriteUse(Use &U) {
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U.set(V);
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}
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/// GetValueAtEndOfBlockInternal - Check to see if AvailableVals has an entry
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/// for the specified BB and if so, return it. If not, construct SSA form by
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/// first calculating the required placement of PHIs and then inserting new
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/// PHIs where needed.
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/// walking predecessors inserting PHI nodes as needed until we get to a block
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/// where the value is available.
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///
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Value *SSAUpdater::GetValueAtEndOfBlockInternal(BasicBlock *BB) {
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AvailableValsTy &AvailableVals = getAvailableVals(AV);
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if (Value *V = AvailableVals[BB])
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return V;
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// Pool allocation used internally by GetValueAtEndOfBlock.
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BumpPtrAllocator AllocatorObj;
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BBMapTy BBMapObj;
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BPA = &AllocatorObj;
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BM = &BBMapObj;
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// Query AvailableVals by doing an insertion of null.
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std::pair<AvailableValsTy::iterator, bool> InsertRes =
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AvailableVals.insert(std::make_pair(BB, TrackingVH<Value>()));
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BBInfo *Info = new (AllocatorObj) BBInfo(BB, 0, &AllocatorObj);
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BBMapObj[BB] = Info;
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// Handle the case when the insertion fails because we have already seen BB.
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if (!InsertRes.second) {
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// If the insertion failed, there are two cases. The first case is that the
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// value is already available for the specified block. If we get this, just
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// return the value.
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if (InsertRes.first->second != 0)
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return InsertRes.first->second;
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bool Changed;
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unsigned Counter = 1;
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do {
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Changed = false;
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FindPHIPlacement(BB, Info, Changed, Counter);
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++Counter;
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} while (Changed);
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FindAvailableVal(BB, Info, Counter);
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BPA = 0;
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BM = 0;
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return Info->AvailableVal;
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}
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/// FindPHIPlacement - Recursively visit the predecessors of a block to find
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/// the reaching definition for each predecessor and then determine whether
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/// a PHI is needed in this block.
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void SSAUpdater::FindPHIPlacement(BasicBlock *BB, BBInfo *Info, bool &Changed,
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unsigned Counter) {
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AvailableValsTy &AvailableVals = getAvailableVals(AV);
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BBMapTy *BBMap = getBBMap(BM);
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BumpPtrAllocator *Allocator = getAllocator(BPA);
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bool BBNeedsPHI = false;
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BasicBlock *SamePredDefBB = 0;
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// If there are no predecessors, then we must have found an unreachable
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// block. Treat it as a definition with 'undef'.
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if (Info->NumPreds == 0) {
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Info->AvailableVal = UndefValue::get(PrototypeValue->getType());
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Info->DefBB = BB;
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return;
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// Otherwise, if the value we find is null, then this is the value is not
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// known but it is being computed elsewhere in our recursion. This means
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// that we have a cycle. Handle this by inserting a PHI node and returning
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// it. When we get back to the first instance of the recursion we will fill
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// in the PHI node.
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return InsertRes.first->second =
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PHINode::Create(PrototypeValue->getType(), PrototypeValue->getName(),
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&BB->front());
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}
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Info->Counter = Counter;
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for (unsigned pi = 0; pi != Info->NumPreds; ++pi) {
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BasicBlock *Pred = Info->Preds[pi];
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BBMapTy::value_type &BBMapBucket = BBMap->FindAndConstruct(Pred);
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if (!BBMapBucket.second) {
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Value *PredVal = AvailableVals.lookup(Pred);
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BBMapBucket.second = new (*Allocator) BBInfo(Pred, PredVal, Allocator);
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// Okay, the value isn't in the map and we just inserted a null in the entry
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// to indicate that we're processing the block. Since we have no idea what
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// value is in this block, we have to recurse through our predecessors.
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//
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// While we're walking our predecessors, we keep track of them in a vector,
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// then insert a PHI node in the end if we actually need one. We could use a
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// smallvector here, but that would take a lot of stack space for every level
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// of the recursion, just use IncomingPredInfo as an explicit stack.
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IncomingPredInfoTy &IncomingPredInfo = getIncomingPredInfo(IPI);
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unsigned FirstPredInfoEntry = IncomingPredInfo.size();
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// As we're walking the predecessors, keep track of whether they are all
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// producing the same value. If so, this value will capture it, if not, it
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// will get reset to null. We distinguish the no-predecessor case explicitly
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// below.
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TrackingVH<Value> ExistingValue;
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// We can get our predecessor info by walking the pred_iterator list, but it
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// is relatively slow. If we already have PHI nodes in this block, walk one
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// of them to get the predecessor list instead.
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if (PHINode *SomePhi = dyn_cast<PHINode>(BB->begin())) {
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for (unsigned i = 0, e = SomePhi->getNumIncomingValues(); i != e; ++i) {
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BasicBlock *PredBB = SomePhi->getIncomingBlock(i);
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Value *PredVal = GetValueAtEndOfBlockInternal(PredBB);
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IncomingPredInfo.push_back(std::make_pair(PredBB, PredVal));
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// Set ExistingValue to singular value from all predecessors so far.
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if (i == 0)
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ExistingValue = PredVal;
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else if (PredVal != ExistingValue)
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ExistingValue = 0;
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}
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BBInfo *PredInfo = BBMapBucket.second;
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BasicBlock *DefBB = 0;
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if (!PredInfo->AvailableVal) {
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if (PredInfo->Counter != Counter)
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FindPHIPlacement(Pred, PredInfo, Changed, Counter);
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} else {
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bool isFirstPred = true;
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for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
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BasicBlock *PredBB = *PI;
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Value *PredVal = GetValueAtEndOfBlockInternal(PredBB);
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IncomingPredInfo.push_back(std::make_pair(PredBB, PredVal));
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// Ignore back edges where the value is not yet known.
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if (!PredInfo->DefBB)
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continue;
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}
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DefBB = PredInfo->DefBB;
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if (!SamePredDefBB)
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SamePredDefBB = DefBB;
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else if (DefBB != SamePredDefBB)
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BBNeedsPHI = true;
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}
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BasicBlock *NewDefBB = (BBNeedsPHI ? BB : SamePredDefBB);
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if (Info->DefBB != NewDefBB) {
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Changed = true;
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Info->DefBB = NewDefBB;
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}
|
||||
}
|
||||
|
||||
/// FindAvailableVal - If this block requires a PHI, first check if an existing
|
||||
/// PHI matches the PHI placement and reaching definitions computed earlier,
|
||||
/// and if not, create a new PHI. Visit all the block's predecessors to
|
||||
/// calculate the available value for each one and fill in the incoming values
|
||||
/// for a new PHI.
|
||||
void SSAUpdater::FindAvailableVal(BasicBlock *BB, BBInfo *Info,
|
||||
unsigned Counter) {
|
||||
if (Info->AvailableVal || Info->Counter == Counter)
|
||||
return;
|
||||
|
||||
AvailableValsTy &AvailableVals = getAvailableVals(AV);
|
||||
BBMapTy *BBMap = getBBMap(BM);
|
||||
|
||||
// Check if there needs to be a PHI in BB.
|
||||
PHINode *NewPHI = 0;
|
||||
if (Info->DefBB == BB) {
|
||||
// Look for an existing PHI.
|
||||
FindExistingPHI(BB);
|
||||
if (!Info->AvailableVal) {
|
||||
NewPHI = PHINode::Create(PrototypeValue->getType(),
|
||||
PrototypeValue->getName(), &BB->front());
|
||||
NewPHI->reserveOperandSpace(Info->NumPreds);
|
||||
Info->AvailableVal = NewPHI;
|
||||
AvailableVals[BB] = NewPHI;
|
||||
// Set ExistingValue to singular value from all predecessors so far.
|
||||
if (isFirstPred) {
|
||||
ExistingValue = PredVal;
|
||||
isFirstPred = false;
|
||||
} else if (PredVal != ExistingValue)
|
||||
ExistingValue = 0;
|
||||
}
|
||||
}
|
||||
|
||||
// Iterate through the block's predecessors.
|
||||
Info->Counter = Counter;
|
||||
for (unsigned pi = 0; pi != Info->NumPreds; ++pi) {
|
||||
BasicBlock *Pred = Info->Preds[pi];
|
||||
BBInfo *PredInfo = (*BBMap)[Pred];
|
||||
FindAvailableVal(Pred, PredInfo, Counter);
|
||||
if (NewPHI) {
|
||||
// Skip to the nearest preceding definition.
|
||||
if (PredInfo->DefBB != Pred)
|
||||
PredInfo = (*BBMap)[PredInfo->DefBB];
|
||||
NewPHI->addIncoming(PredInfo->AvailableVal, Pred);
|
||||
} else if (!Info->AvailableVal)
|
||||
Info->AvailableVal = PredInfo->AvailableVal;
|
||||
// If there are no predecessors, then we must have found an unreachable block
|
||||
// just return 'undef'. Since there are no predecessors, InsertRes must not
|
||||
// be invalidated.
|
||||
if (IncomingPredInfo.size() == FirstPredInfoEntry)
|
||||
return InsertRes.first->second = UndefValue::get(PrototypeValue->getType());
|
||||
|
||||
/// Look up BB's entry in AvailableVals. 'InsertRes' may be invalidated. If
|
||||
/// this block is involved in a loop, a no-entry PHI node will have been
|
||||
/// inserted as InsertedVal. Otherwise, we'll still have the null we inserted
|
||||
/// above.
|
||||
TrackingVH<Value> &InsertedVal = AvailableVals[BB];
|
||||
|
||||
// If the predecessor values are not all the same, then check to see if there
|
||||
// is an existing PHI that can be used.
|
||||
if (!ExistingValue)
|
||||
ExistingValue = GetExistingPHI(BB,
|
||||
IncomingPredInfo.begin()+FirstPredInfoEntry,
|
||||
IncomingPredInfo.end());
|
||||
|
||||
// If there is an existing value we can use, then we don't need to insert a
|
||||
// PHI. This is the simple and common case.
|
||||
if (ExistingValue) {
|
||||
// If a PHI node got inserted, replace it with the existing value and delete
|
||||
// it.
|
||||
if (InsertedVal) {
|
||||
PHINode *OldVal = cast<PHINode>(InsertedVal);
|
||||
// Be careful about dead loops. These RAUW's also update InsertedVal.
|
||||
if (InsertedVal != ExistingValue)
|
||||
OldVal->replaceAllUsesWith(ExistingValue);
|
||||
else
|
||||
OldVal->replaceAllUsesWith(UndefValue::get(InsertedVal->getType()));
|
||||
OldVal->eraseFromParent();
|
||||
} else {
|
||||
InsertedVal = ExistingValue;
|
||||
}
|
||||
|
||||
// Either path through the 'if' should have set InsertedVal -> ExistingVal.
|
||||
assert((InsertedVal == ExistingValue || isa<UndefValue>(InsertedVal)) &&
|
||||
"RAUW didn't change InsertedVal to be ExistingValue");
|
||||
|
||||
// Drop the entries we added in IncomingPredInfo to restore the stack.
|
||||
IncomingPredInfo.erase(IncomingPredInfo.begin()+FirstPredInfoEntry,
|
||||
IncomingPredInfo.end());
|
||||
return ExistingValue;
|
||||
}
|
||||
|
||||
if (NewPHI) {
|
||||
DEBUG(dbgs() << " Inserted PHI: " << *NewPHI << "\n");
|
||||
// Otherwise, we do need a PHI: insert one now if we don't already have one.
|
||||
if (InsertedVal == 0)
|
||||
InsertedVal = PHINode::Create(PrototypeValue->getType(),
|
||||
PrototypeValue->getName(), &BB->front());
|
||||
|
||||
PHINode *InsertedPHI = cast<PHINode>(InsertedVal);
|
||||
InsertedPHI->reserveOperandSpace(IncomingPredInfo.size()-FirstPredInfoEntry);
|
||||
|
||||
// Fill in all the predecessors of the PHI.
|
||||
for (IncomingPredInfoTy::iterator I =
|
||||
IncomingPredInfo.begin()+FirstPredInfoEntry,
|
||||
E = IncomingPredInfo.end(); I != E; ++I)
|
||||
InsertedPHI->addIncoming(I->second, I->first);
|
||||
|
||||
// Drop the entries we added in IncomingPredInfo to restore the stack.
|
||||
IncomingPredInfo.erase(IncomingPredInfo.begin()+FirstPredInfoEntry,
|
||||
IncomingPredInfo.end());
|
||||
|
||||
// See if the PHI node can be merged to a single value. This can happen in
|
||||
// loop cases when we get a PHI of itself and one other value.
|
||||
if (Value *ConstVal = InsertedPHI->hasConstantValue()) {
|
||||
InsertedPHI->replaceAllUsesWith(ConstVal);
|
||||
InsertedPHI->eraseFromParent();
|
||||
InsertedVal = ConstVal;
|
||||
} else {
|
||||
DEBUG(dbgs() << " Inserted PHI: " << *InsertedPHI << "\n");
|
||||
|
||||
// If the client wants to know about all new instructions, tell it.
|
||||
if (InsertedPHIs) InsertedPHIs->push_back(NewPHI);
|
||||
}
|
||||
}
|
||||
|
||||
/// FindExistingPHI - Look through the PHI nodes in a block to see if any of
|
||||
/// them match what is needed.
|
||||
void SSAUpdater::FindExistingPHI(BasicBlock *BB) {
|
||||
PHINode *SomePHI;
|
||||
for (BasicBlock::iterator It = BB->begin();
|
||||
(SomePHI = dyn_cast<PHINode>(It)); ++It) {
|
||||
if (CheckIfPHIMatches(SomePHI)) {
|
||||
RecordMatchingPHI(SomePHI);
|
||||
break;
|
||||
}
|
||||
ClearPHITags(SomePHI);
|
||||
}
|
||||
}
|
||||
|
||||
/// CheckIfPHIMatches - Check if a PHI node matches the placement and values
|
||||
/// in the BBMap.
|
||||
bool SSAUpdater::CheckIfPHIMatches(PHINode *PHI) {
|
||||
BBMapTy *BBMap = getBBMap(BM);
|
||||
SmallVector<PHINode*, 20> WorkList;
|
||||
WorkList.push_back(PHI);
|
||||
|
||||
// Mark that the block containing this PHI has been visited.
|
||||
(*BBMap)[PHI->getParent()]->PHITag = PHI;
|
||||
|
||||
while (!WorkList.empty()) {
|
||||
PHI = WorkList.pop_back_val();
|
||||
|
||||
// Iterate through the PHI's incoming values.
|
||||
for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i) {
|
||||
Value *IncomingVal = PHI->getIncomingValue(i);
|
||||
BasicBlock *Pred = PHI->getIncomingBlock(i);
|
||||
BBInfo *PredInfo = (*BBMap)[Pred];
|
||||
// Skip to the nearest preceding definition.
|
||||
if (PredInfo->DefBB != Pred) {
|
||||
Pred = PredInfo->DefBB;
|
||||
PredInfo = (*BBMap)[Pred];
|
||||
}
|
||||
|
||||
// Check if it matches the expected value.
|
||||
if (PredInfo->AvailableVal) {
|
||||
if (IncomingVal == PredInfo->AvailableVal)
|
||||
continue;
|
||||
return false;
|
||||
}
|
||||
|
||||
// Check if the value is a PHI in the correct block.
|
||||
PHINode *IncomingPHIVal = dyn_cast<PHINode>(IncomingVal);
|
||||
if (!IncomingPHIVal || IncomingPHIVal->getParent() != Pred)
|
||||
return false;
|
||||
|
||||
// If this block has already been visited, check if this PHI matches.
|
||||
if (PredInfo->PHITag) {
|
||||
if (IncomingPHIVal == PredInfo->PHITag)
|
||||
continue;
|
||||
return false;
|
||||
}
|
||||
PredInfo->PHITag = IncomingPHIVal;
|
||||
|
||||
WorkList.push_back(IncomingPHIVal);
|
||||
}
|
||||
}
|
||||
return true;
|
||||
}
|
||||
|
||||
/// RecordMatchingPHI - For a PHI node that matches, record it and its input
|
||||
/// PHIs in both the BBMap and the AvailableVals mapping.
|
||||
void SSAUpdater::RecordMatchingPHI(PHINode *PHI) {
|
||||
BBMapTy *BBMap = getBBMap(BM);
|
||||
AvailableValsTy &AvailableVals = getAvailableVals(AV);
|
||||
SmallVector<PHINode*, 20> WorkList;
|
||||
WorkList.push_back(PHI);
|
||||
|
||||
// Record this PHI.
|
||||
BasicBlock *BB = PHI->getParent();
|
||||
AvailableVals[BB] = PHI;
|
||||
(*BBMap)[BB]->AvailableVal = PHI;
|
||||
|
||||
while (!WorkList.empty()) {
|
||||
PHI = WorkList.pop_back_val();
|
||||
|
||||
// Iterate through the PHI's incoming values.
|
||||
for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i) {
|
||||
PHINode *IncomingPHIVal = dyn_cast<PHINode>(PHI->getIncomingValue(i));
|
||||
if (!IncomingPHIVal) continue;
|
||||
BB = IncomingPHIVal->getParent();
|
||||
BBInfo *Info = (*BBMap)[BB];
|
||||
if (!Info || Info->AvailableVal)
|
||||
continue;
|
||||
|
||||
// Record the PHI and add it to the worklist.
|
||||
AvailableVals[BB] = IncomingPHIVal;
|
||||
Info->AvailableVal = IncomingPHIVal;
|
||||
WorkList.push_back(IncomingPHIVal);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// ClearPHITags - When one of the existing PHI nodes fails to match, clear
|
||||
/// the PHITag values that were stored in the BBMap when checking to see if
|
||||
/// it matched.
|
||||
void SSAUpdater::ClearPHITags(PHINode *PHI) {
|
||||
BBMapTy *BBMap = getBBMap(BM);
|
||||
SmallVector<PHINode*, 20> WorkList;
|
||||
WorkList.push_back(PHI);
|
||||
|
||||
// Clear the tag for this PHI.
|
||||
(*BBMap)[PHI->getParent()]->PHITag = 0;
|
||||
|
||||
while (!WorkList.empty()) {
|
||||
PHI = WorkList.pop_back_val();
|
||||
|
||||
// Iterate through the PHI's incoming values.
|
||||
for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i) {
|
||||
PHINode *IncomingPHIVal = dyn_cast<PHINode>(PHI->getIncomingValue(i));
|
||||
if (!IncomingPHIVal) continue;
|
||||
BasicBlock *BB = IncomingPHIVal->getParent();
|
||||
BBInfo *Info = (*BBMap)[BB];
|
||||
if (!Info || Info->AvailableVal || !Info->PHITag)
|
||||
continue;
|
||||
|
||||
// Clear the tag and add the PHI to the worklist.
|
||||
Info->PHITag = 0;
|
||||
WorkList.push_back(IncomingPHIVal);
|
||||
}
|
||||
if (InsertedPHIs) InsertedPHIs->push_back(InsertedPHI);
|
||||
}
|
||||
|
||||
return InsertedVal;
|
||||
}
|
||||
|
||||
@ -1,46 +0,0 @@
|
||||
; RUN: opt < %s -gvn -enable-full-load-pre -S | FileCheck %s
|
||||
|
||||
define i8* @cat(i8* %s1, ...) nounwind {
|
||||
entry:
|
||||
br i1 undef, label %bb, label %bb3
|
||||
|
||||
bb: ; preds = %entry
|
||||
unreachable
|
||||
|
||||
bb3: ; preds = %entry
|
||||
store i8* undef, i8** undef, align 4
|
||||
br i1 undef, label %bb5, label %bb6
|
||||
|
||||
bb5: ; preds = %bb3
|
||||
unreachable
|
||||
|
||||
bb6: ; preds = %bb3
|
||||
br label %bb12
|
||||
|
||||
bb8: ; preds = %bb12
|
||||
br i1 undef, label %bb9, label %bb10
|
||||
|
||||
bb9: ; preds = %bb8
|
||||
%0 = load i8** undef, align 4 ; <i8*> [#uses=0]
|
||||
%1 = load i8** undef, align 4 ; <i8*> [#uses=0]
|
||||
br label %bb11
|
||||
|
||||
bb10: ; preds = %bb8
|
||||
br label %bb11
|
||||
|
||||
bb11: ; preds = %bb10, %bb9
|
||||
; CHECK: bb11:
|
||||
; CHECK: phi
|
||||
; CHECK-NOT: phi
|
||||
br label %bb12
|
||||
|
||||
bb12: ; preds = %bb11, %bb6
|
||||
; CHECK: bb12:
|
||||
; CHECK: phi
|
||||
; CHECK-NOT: phi
|
||||
br i1 undef, label %bb8, label %bb13
|
||||
|
||||
bb13: ; preds = %bb12
|
||||
; CHECK: bb13:
|
||||
ret i8* undef
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user