//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "mem2reg"
#include "llvm/Transforms/Utils/PromoteMemToReg.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/AliasSetTracker.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/CFG.h"
-#include "llvm/Support/StableBasicBlockNumbering.h"
#include "llvm/Support/Compiler.h"
#include <algorithm>
using namespace llvm;
+STATISTIC(NumLocalPromoted, "Number of alloca's promoted within one block");
+STATISTIC(NumSingleStore, "Number of alloca's promoted with a single store");
+STATISTIC(NumDeadAlloca, "Number of dead alloca's removed");
+
+// Provide DenseMapKeyInfo for all pointers.
+namespace llvm {
+template<>
+struct DenseMapKeyInfo<std::pair<BasicBlock*, unsigned> > {
+ static inline std::pair<BasicBlock*, unsigned> getEmptyKey() {
+ return std::make_pair((BasicBlock*)-1, ~0U);
+ }
+ static inline std::pair<BasicBlock*, unsigned> getTombstoneKey() {
+ return std::make_pair((BasicBlock*)-2, 0U);
+ }
+ static unsigned getHashValue(const std::pair<BasicBlock*, unsigned> &Val) {
+ return DenseMapKeyInfo<void*>::getHashValue(Val.first) + Val.second*2;
+ }
+ static bool isPod() { return true; }
+};
+}
+
/// isAllocaPromotable - Return true if this alloca is legal for promotion.
/// This is true if there are only loads and stores to the alloca.
///
-bool llvm::isAllocaPromotable(const AllocaInst *AI, const TargetData &TD) {
+bool llvm::isAllocaPromotable(const AllocaInst *AI) {
// FIXME: If the memory unit is of pointer or integer type, we can permit
// assignments to subsections of the memory unit.
}
namespace {
+ struct AllocaInfo;
+
+ // Data package used by RenamePass()
+ class VISIBILITY_HIDDEN RenamePassData {
+ public:
+ typedef std::vector<Value *> ValVector;
+
+ RenamePassData() {}
+ RenamePassData(BasicBlock *B, BasicBlock *P,
+ const ValVector &V) : BB(B), Pred(P), Values(V) {}
+ BasicBlock *BB;
+ BasicBlock *Pred;
+ ValVector Values;
+
+ void swap(RenamePassData &RHS) {
+ std::swap(BB, RHS.BB);
+ std::swap(Pred, RHS.Pred);
+ Values.swap(RHS.Values);
+ }
+ };
+
struct VISIBILITY_HIDDEN PromoteMem2Reg {
/// Allocas - The alloca instructions being promoted.
///
SmallVector<AllocaInst*, 16> &RetryList;
DominatorTree &DT;
DominanceFrontier &DF;
- const TargetData &TD;
/// AST - An AliasSetTracker object to update. If null, don't update it.
///
/// NewPhiNodes - The PhiNodes we're adding.
///
- std::map<BasicBlock*, std::vector<PHINode*> > NewPhiNodes;
-
+ DenseMap<std::pair<BasicBlock*, unsigned>, PHINode*> NewPhiNodes;
+
+ /// PhiToAllocaMap - For each PHI node, keep track of which entry in Allocas
+ /// it corresponds to.
+ DenseMap<PHINode*, unsigned> PhiToAllocaMap;
+
/// PointerAllocaValues - If we are updating an AliasSetTracker, then for
/// each alloca that is of pointer type, we keep track of what to copyValue
/// to the inserted PHI nodes here.
/// BBNumbers - Contains a stable numbering of basic blocks to avoid
/// non-determinstic behavior.
- StableBasicBlockNumbering BBNumbers;
+ DenseMap<BasicBlock*, unsigned> BBNumbers;
public:
PromoteMem2Reg(const std::vector<AllocaInst*> &A,
SmallVector<AllocaInst*, 16> &Retry, DominatorTree &dt,
- DominanceFrontier &df, const TargetData &td,
- AliasSetTracker *ast)
- : Allocas(A), RetryList(Retry), DT(dt), DF(df), TD(td), AST(ast) {}
+ DominanceFrontier &df, AliasSetTracker *ast)
+ : Allocas(A), RetryList(Retry), DT(dt), DF(df), AST(ast) {}
void run();
bool properlyDominates(Instruction *I1, Instruction *I2) const {
if (InvokeInst *II = dyn_cast<InvokeInst>(I1))
I1 = II->getNormalDest()->begin();
- return DT[I1->getParent()]->properlyDominates(DT[I2->getParent()]);
+ return DT.properlyDominates(I1->getParent(), I2->getParent());
}
/// dominates - Return true if BB1 dominates BB2 using the DominatorTree.
///
bool dominates(BasicBlock *BB1, BasicBlock *BB2) const {
- return DT[BB1]->dominates(DT[BB2]);
+ return DT.dominates(BB1, BB2);
}
private:
+ void RemoveFromAllocasList(unsigned &AllocaIdx) {
+ Allocas[AllocaIdx] = Allocas.back();
+ Allocas.pop_back();
+ --AllocaIdx;
+ }
+
+ void RewriteSingleStoreAlloca(AllocaInst *AI, AllocaInfo &Info);
+
void MarkDominatingPHILive(BasicBlock *BB, unsigned AllocaNum,
SmallPtrSet<PHINode*, 16> &DeadPHINodes);
bool PromoteLocallyUsedAlloca(BasicBlock *BB, AllocaInst *AI);
const std::vector<AllocaInst*> &AIs);
void RenamePass(BasicBlock *BB, BasicBlock *Pred,
- std::vector<Value*> &IncVals);
+ RenamePassData::ValVector &IncVals,
+ std::vector<RenamePassData> &Worklist);
bool QueuePhiNode(BasicBlock *BB, unsigned AllocaIdx, unsigned &Version,
SmallPtrSet<PHINode*, 16> &InsertedPHINodes);
};
+
+ struct AllocaInfo {
+ std::vector<BasicBlock*> DefiningBlocks;
+ std::vector<BasicBlock*> UsingBlocks;
+
+ StoreInst *OnlyStore;
+ BasicBlock *OnlyBlock;
+ bool OnlyUsedInOneBlock;
+
+ Value *AllocaPointerVal;
+
+ void clear() {
+ DefiningBlocks.clear();
+ UsingBlocks.clear();
+ OnlyStore = 0;
+ OnlyBlock = 0;
+ OnlyUsedInOneBlock = true;
+ AllocaPointerVal = 0;
+ }
+
+ /// AnalyzeAlloca - Scan the uses of the specified alloca, filling in our
+ /// ivars.
+ void AnalyzeAlloca(AllocaInst *AI) {
+ clear();
+
+ // As we scan the uses of the alloca instruction, keep track of stores,
+ // and decide whether all of the loads and stores to the alloca are within
+ // the same basic block.
+ for (Value::use_iterator U = AI->use_begin(), E = AI->use_end();
+ U != E; ++U){
+ Instruction *User = cast<Instruction>(*U);
+ if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
+ // Remember the basic blocks which define new values for the alloca
+ DefiningBlocks.push_back(SI->getParent());
+ AllocaPointerVal = SI->getOperand(0);
+ OnlyStore = SI;
+ } else {
+ LoadInst *LI = cast<LoadInst>(User);
+ // Otherwise it must be a load instruction, keep track of variable reads
+ UsingBlocks.push_back(LI->getParent());
+ AllocaPointerVal = LI;
+ }
+
+ if (OnlyUsedInOneBlock) {
+ if (OnlyBlock == 0)
+ OnlyBlock = User->getParent();
+ else if (OnlyBlock != User->getParent())
+ OnlyUsedInOneBlock = false;
+ }
+ }
+ }
+ };
+
} // end of anonymous namespace
+
void PromoteMem2Reg::run() {
Function &F = *DF.getRoot()->getParent();
if (AST) PointerAllocaValues.resize(Allocas.size());
+ AllocaInfo Info;
+
for (unsigned AllocaNum = 0; AllocaNum != Allocas.size(); ++AllocaNum) {
AllocaInst *AI = Allocas[AllocaNum];
- assert(isAllocaPromotable(AI, TD) &&
+ assert(isAllocaPromotable(AI) &&
"Cannot promote non-promotable alloca!");
assert(AI->getParent()->getParent() == &F &&
"All allocas should be in the same function, which is same as DF!");
AI->eraseFromParent();
// Remove the alloca from the Allocas list, since it has been processed
- Allocas[AllocaNum] = Allocas.back();
- Allocas.pop_back();
- --AllocaNum;
+ RemoveFromAllocasList(AllocaNum);
+ ++NumDeadAlloca;
continue;
}
-
+
// Calculate the set of read and write-locations for each alloca. This is
// analogous to finding the 'uses' and 'definitions' of each variable.
- std::vector<BasicBlock*> DefiningBlocks;
- std::vector<BasicBlock*> UsingBlocks;
-
- StoreInst *OnlyStore = 0;
- BasicBlock *OnlyBlock = 0;
- bool OnlyUsedInOneBlock = true;
-
- // As we scan the uses of the alloca instruction, keep track of stores, and
- // decide whether all of the loads and stores to the alloca are within the
- // same basic block.
- Value *AllocaPointerVal = 0;
- for (Value::use_iterator U =AI->use_begin(), E = AI->use_end(); U != E;++U){
- Instruction *User = cast<Instruction>(*U);
- if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
- // Remember the basic blocks which define new values for the alloca
- DefiningBlocks.push_back(SI->getParent());
- AllocaPointerVal = SI->getOperand(0);
- OnlyStore = SI;
- } else {
- LoadInst *LI = cast<LoadInst>(User);
- // Otherwise it must be a load instruction, keep track of variable reads
- UsingBlocks.push_back(LI->getParent());
- AllocaPointerVal = LI;
- }
-
- if (OnlyUsedInOneBlock) {
- if (OnlyBlock == 0)
- OnlyBlock = User->getParent();
- else if (OnlyBlock != User->getParent())
- OnlyUsedInOneBlock = false;
- }
- }
+ Info.AnalyzeAlloca(AI);
// If the alloca is only read and written in one basic block, just perform a
// linear sweep over the block to eliminate it.
- if (OnlyUsedInOneBlock) {
- LocallyUsedAllocas[OnlyBlock].push_back(AI);
+ if (Info.OnlyUsedInOneBlock) {
+ LocallyUsedAllocas[Info.OnlyBlock].push_back(AI);
// Remove the alloca from the Allocas list, since it will be processed.
- Allocas[AllocaNum] = Allocas.back();
- Allocas.pop_back();
- --AllocaNum;
+ RemoveFromAllocasList(AllocaNum);
continue;
}
// If there is only a single store to this value, replace any loads of
// it that are directly dominated by the definition with the value stored.
- if (DefiningBlocks.size() == 1) {
- // Be aware of loads before the store.
- std::set<BasicBlock*> ProcessedBlocks;
- for (unsigned i = 0, e = UsingBlocks.size(); i != e; ++i)
- // If the store dominates the block and if we haven't processed it yet,
- // do so now.
- if (dominates(OnlyStore->getParent(), UsingBlocks[i]))
- if (ProcessedBlocks.insert(UsingBlocks[i]).second) {
- BasicBlock *UseBlock = UsingBlocks[i];
-
- // If the use and store are in the same block, do a quick scan to
- // verify that there are no uses before the store.
- if (UseBlock == OnlyStore->getParent()) {
- BasicBlock::iterator I = UseBlock->begin();
- for (; &*I != OnlyStore; ++I) { // scan block for store.
- if (isa<LoadInst>(I) && I->getOperand(0) == AI)
- break;
- }
- if (&*I != OnlyStore) break; // Do not handle this case.
- }
-
- // Otherwise, if this is a different block or if all uses happen
- // after the store, do a simple linear scan to replace loads with
- // the stored value.
- for (BasicBlock::iterator I = UseBlock->begin(),E = UseBlock->end();
- I != E; ) {
- if (LoadInst *LI = dyn_cast<LoadInst>(I++)) {
- if (LI->getOperand(0) == AI) {
- LI->replaceAllUsesWith(OnlyStore->getOperand(0));
- if (AST && isa<PointerType>(LI->getType()))
- AST->deleteValue(LI);
- LI->eraseFromParent();
- }
- }
- }
-
- // Finally, remove this block from the UsingBlock set.
- UsingBlocks[i] = UsingBlocks.back();
- --i; --e;
- }
+ if (Info.DefiningBlocks.size() == 1) {
+ RewriteSingleStoreAlloca(AI, Info);
// Finally, after the scan, check to see if the store is all that is left.
- if (UsingBlocks.empty()) {
+ if (Info.UsingBlocks.empty()) {
+ ++NumSingleStore;
// The alloca has been processed, move on.
- Allocas[AllocaNum] = Allocas.back();
- Allocas.pop_back();
- --AllocaNum;
+ RemoveFromAllocasList(AllocaNum);
continue;
}
}
if (AST)
- PointerAllocaValues[AllocaNum] = AllocaPointerVal;
+ PointerAllocaValues[AllocaNum] = Info.AllocaPointerVal;
// If we haven't computed a numbering for the BB's in the function, do so
// now.
- BBNumbers.compute(F);
+ if (BBNumbers.empty()) {
+ unsigned ID = 0;
+ for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
+ BBNumbers[I] = ID++;
+ }
// Compute the locations where PhiNodes need to be inserted. Look at the
// dominance frontier of EACH basic-block we have a write in.
//
unsigned CurrentVersion = 0;
SmallPtrSet<PHINode*, 16> InsertedPHINodes;
- std::vector<unsigned> DFBlocks;
- while (!DefiningBlocks.empty()) {
- BasicBlock *BB = DefiningBlocks.back();
- DefiningBlocks.pop_back();
+ std::vector<std::pair<unsigned, BasicBlock*> > DFBlocks;
+ while (!Info.DefiningBlocks.empty()) {
+ BasicBlock *BB = Info.DefiningBlocks.back();
+ Info.DefiningBlocks.pop_back();
// Look up the DF for this write, add it to PhiNodes
DominanceFrontier::const_iterator it = DF.find(BB);
// processing blocks in order of the occurance in the function.
for (DominanceFrontier::DomSetType::const_iterator P = S.begin(),
PE = S.end(); P != PE; ++P)
- DFBlocks.push_back(BBNumbers.getNumber(*P));
+ DFBlocks.push_back(std::make_pair(BBNumbers[*P], *P));
// Sort by which the block ordering in the function.
std::sort(DFBlocks.begin(), DFBlocks.end());
for (unsigned i = 0, e = DFBlocks.size(); i != e; ++i) {
- BasicBlock *BB = BBNumbers.getBlock(DFBlocks[i]);
+ BasicBlock *BB = DFBlocks[i].second;
if (QueuePhiNode(BB, AllocaNum, CurrentVersion, InsertedPHINodes))
- DefiningBlocks.push_back(BB);
+ Info.DefiningBlocks.push_back(BB);
}
DFBlocks.clear();
}
// marked alive because of loads which are dominated by stores, but there
// will be no unmarked PHI nodes which are actually used.
//
- for (unsigned i = 0, e = UsingBlocks.size(); i != e; ++i)
- MarkDominatingPHILive(UsingBlocks[i], AllocaNum, InsertedPHINodes);
- UsingBlocks.clear();
+ for (unsigned i = 0, e = Info.UsingBlocks.size(); i != e; ++i)
+ MarkDominatingPHILive(Info.UsingBlocks[i], AllocaNum, InsertedPHINodes);
+ Info.UsingBlocks.clear();
// If there are any PHI nodes which are now known to be dead, remove them!
for (SmallPtrSet<PHINode*, 16>::iterator I = InsertedPHINodes.begin(),
E = InsertedPHINodes.end(); I != E; ++I) {
PHINode *PN = *I;
- std::vector<PHINode*> &BBPNs = NewPhiNodes[PN->getParent()];
- BBPNs[AllocaNum] = 0;
-
- // Check to see if we just removed the last inserted PHI node from this
- // basic block. If so, remove the entry for the basic block.
- bool HasOtherPHIs = false;
- for (unsigned i = 0, e = BBPNs.size(); i != e; ++i)
- if (BBPNs[i]) {
- HasOtherPHIs = true;
- break;
- }
- if (!HasOtherPHIs)
- NewPhiNodes.erase(PN->getParent());
-
+ bool Erased=NewPhiNodes.erase(std::make_pair(PN->getParent(), AllocaNum));
+ Erased=Erased;
+ assert(Erased && "PHI already removed?");
+
if (AST && isa<PointerType>(PN->getType()))
AST->deleteValue(PN);
PN->eraseFromParent();
+ PhiToAllocaMap.erase(PN);
}
// Keep the reverse mapping of the 'Allocas' array.
// the alloca's. We do this in case there is a load of a value that has not
// been stored yet. In this case, it will get this null value.
//
- std::vector<Value *> Values(Allocas.size());
+ RenamePassData::ValVector Values(Allocas.size());
for (unsigned i = 0, e = Allocas.size(); i != e; ++i)
Values[i] = UndefValue::get(Allocas[i]->getAllocatedType());
// Walks all basic blocks in the function performing the SSA rename algorithm
// and inserting the phi nodes we marked as necessary
//
- RenamePass(F.begin(), 0, Values);
-
+ std::vector<RenamePassData> RenamePassWorkList;
+ RenamePassWorkList.push_back(RenamePassData(F.begin(), 0, Values));
+ while (!RenamePassWorkList.empty()) {
+ RenamePassData RPD;
+ RPD.swap(RenamePassWorkList.back());
+ RenamePassWorkList.pop_back();
+ // RenamePass may add new worklist entries.
+ RenamePass(RPD.BB, RPD.Pred, RPD.Values, RenamePassWorkList);
+ }
+
// The renamer uses the Visited set to avoid infinite loops. Clear it now.
Visited.clear();
while (EliminatedAPHI) {
EliminatedAPHI = false;
- for (std::map<BasicBlock*, std::vector<PHINode *> >::iterator I =
- NewPhiNodes.begin(), E = NewPhiNodes.end(); I != E; ++I) {
- std::vector<PHINode*> &PNs = I->second;
- for (unsigned i = 0, e = PNs.size(); i != e; ++i) {
- if (!PNs[i]) continue;
-
- // If this PHI node merges one value and/or undefs, get the value.
- if (Value *V = PNs[i]->hasConstantValue(true)) {
- if (!isa<Instruction>(V) ||
- properlyDominates(cast<Instruction>(V), PNs[i])) {
- if (AST && isa<PointerType>(PNs[i]->getType()))
- AST->deleteValue(PNs[i]);
- PNs[i]->replaceAllUsesWith(V);
- PNs[i]->eraseFromParent();
- PNs[i] = 0;
- EliminatedAPHI = true;
- continue;
- }
+ for (DenseMap<std::pair<BasicBlock*, unsigned>, PHINode*>::iterator I =
+ NewPhiNodes.begin(), E = NewPhiNodes.end(); I != E;) {
+ PHINode *PN = I->second;
+
+ // If this PHI node merges one value and/or undefs, get the value.
+ if (Value *V = PN->hasConstantValue(true)) {
+ if (!isa<Instruction>(V) ||
+ properlyDominates(cast<Instruction>(V), PN)) {
+ if (AST && isa<PointerType>(PN->getType()))
+ AST->deleteValue(PN);
+ PN->replaceAllUsesWith(V);
+ PN->eraseFromParent();
+ NewPhiNodes.erase(I++);
+ EliminatedAPHI = true;
+ continue;
}
}
+ ++I;
}
}
// have incoming values for all predecessors. Loop over all PHI nodes we have
// created, inserting undef values if they are missing any incoming values.
//
- for (std::map<BasicBlock*, std::vector<PHINode *> >::iterator I =
+ for (DenseMap<std::pair<BasicBlock*, unsigned>, PHINode*>::iterator I =
NewPhiNodes.begin(), E = NewPhiNodes.end(); I != E; ++I) {
+ // We want to do this once per basic block. As such, only process a block
+ // when we find the PHI that is the first entry in the block.
+ PHINode *SomePHI = I->second;
+ BasicBlock *BB = SomePHI->getParent();
+ if (&BB->front() != SomePHI)
+ continue;
- std::vector<BasicBlock*> Preds(pred_begin(I->first), pred_end(I->first));
- std::vector<PHINode*> &PNs = I->second;
- assert(!PNs.empty() && "Empty PHI node list??");
- PHINode *SomePHI = 0;
- for (unsigned i = 0, e = PNs.size(); i != e; ++i)
- if (PNs[i]) {
- SomePHI = PNs[i];
- break;
- }
+ // Count the number of preds for BB.
+ SmallVector<BasicBlock*, 16> Preds(pred_begin(BB), pred_end(BB));
// Only do work here if there the PHI nodes are missing incoming values. We
// know that all PHI nodes that were inserted in a block will have the same
- // number of incoming values, so we can just check any PHI node.
- if (SomePHI && Preds.size() != SomePHI->getNumIncomingValues()) {
- // Ok, now we know that all of the PHI nodes are missing entries for some
- // basic blocks. Start by sorting the incoming predecessors for efficient
- // access.
- std::sort(Preds.begin(), Preds.end());
-
- // Now we loop through all BB's which have entries in SomePHI and remove
- // them from the Preds list.
- for (unsigned i = 0, e = SomePHI->getNumIncomingValues(); i != e; ++i) {
- // Do a log(n) search of the Preds list for the entry we want.
- std::vector<BasicBlock*>::iterator EntIt =
- std::lower_bound(Preds.begin(), Preds.end(),
- SomePHI->getIncomingBlock(i));
- assert(EntIt != Preds.end() && *EntIt == SomePHI->getIncomingBlock(i)&&
- "PHI node has entry for a block which is not a predecessor!");
-
- // Remove the entry
- Preds.erase(EntIt);
- }
+ // number of incoming values, so we can just check any of them.
+ if (SomePHI->getNumIncomingValues() == Preds.size())
+ continue;
+
+ // Ok, now we know that all of the PHI nodes are missing entries for some
+ // basic blocks. Start by sorting the incoming predecessors for efficient
+ // access.
+ std::sort(Preds.begin(), Preds.end());
+
+ // Now we loop through all BB's which have entries in SomePHI and remove
+ // them from the Preds list.
+ for (unsigned i = 0, e = SomePHI->getNumIncomingValues(); i != e; ++i) {
+ // Do a log(n) search of the Preds list for the entry we want.
+ SmallVector<BasicBlock*, 16>::iterator EntIt =
+ std::lower_bound(Preds.begin(), Preds.end(),
+ SomePHI->getIncomingBlock(i));
+ assert(EntIt != Preds.end() && *EntIt == SomePHI->getIncomingBlock(i)&&
+ "PHI node has entry for a block which is not a predecessor!");
+
+ // Remove the entry
+ Preds.erase(EntIt);
+ }
- // At this point, the blocks left in the preds list must have dummy
- // entries inserted into every PHI nodes for the block.
- for (unsigned i = 0, e = PNs.size(); i != e; ++i)
- if (PHINode *PN = PNs[i]) {
- Value *UndefVal = UndefValue::get(PN->getType());
- for (unsigned pred = 0, e = Preds.size(); pred != e; ++pred)
- PN->addIncoming(UndefVal, Preds[pred]);
+ // At this point, the blocks left in the preds list must have dummy
+ // entries inserted into every PHI nodes for the block. Update all the phi
+ // nodes in this block that we are inserting (there could be phis before
+ // mem2reg runs).
+ unsigned NumBadPreds = SomePHI->getNumIncomingValues();
+ BasicBlock::iterator BBI = BB->begin();
+ while ((SomePHI = dyn_cast<PHINode>(BBI++)) &&
+ SomePHI->getNumIncomingValues() == NumBadPreds) {
+ Value *UndefVal = UndefValue::get(SomePHI->getType());
+ for (unsigned pred = 0, e = Preds.size(); pred != e; ++pred)
+ SomePHI->addIncoming(UndefVal, Preds[pred]);
+ }
+ }
+
+ NewPhiNodes.clear();
+}
+
+
+/// RewriteSingleStoreAlloca - If there is only a single store to this value,
+/// replace any loads of it that are directly dominated by the definition with
+/// the value stored.
+void PromoteMem2Reg::RewriteSingleStoreAlloca(AllocaInst *AI,
+ AllocaInfo &Info) {
+ // Be aware of loads before the store.
+ std::set<BasicBlock*> ProcessedBlocks;
+ for (unsigned i = 0, e = Info.UsingBlocks.size(); i != e; ++i) {
+ // If the store dominates the block and if we haven't processed it yet,
+ // do so now.
+ if (!dominates(Info.OnlyStore->getParent(), Info.UsingBlocks[i]))
+ continue;
+
+ if (!ProcessedBlocks.insert(Info.UsingBlocks[i]).second)
+ continue;
+
+ BasicBlock *UseBlock = Info.UsingBlocks[i];
+
+ // If the use and store are in the same block, do a quick scan to
+ // verify that there are no uses before the store.
+ if (UseBlock == Info.OnlyStore->getParent()) {
+ BasicBlock::iterator I = UseBlock->begin();
+ for (; &*I != Info.OnlyStore; ++I) { // scan block for store.
+ if (isa<LoadInst>(I) && I->getOperand(0) == AI)
+ break;
+ }
+ if (&*I != Info.OnlyStore) break; // Do not handle this case.
+ }
+
+ // Otherwise, if this is a different block or if all uses happen
+ // after the store, do a simple linear scan to replace loads with
+ // the stored value.
+ for (BasicBlock::iterator I = UseBlock->begin(),E = UseBlock->end();
+ I != E; ) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(I++)) {
+ if (LI->getOperand(0) == AI) {
+ LI->replaceAllUsesWith(Info.OnlyStore->getOperand(0));
+ if (AST && isa<PointerType>(LI->getType()))
+ AST->deleteValue(LI);
+ LI->eraseFromParent();
}
+ }
}
+
+ // Finally, remove this block from the UsingBlock set.
+ Info.UsingBlocks[i] = Info.UsingBlocks.back();
+ --i; --e;
}
}
+
// MarkDominatingPHILive - Mem2Reg wants to construct "pruned" SSA form, not
// "minimal" SSA form. To do this, it inserts all of the PHI nodes on the IDF
// as usual (inserting the PHI nodes in the DeadPHINodes set), then processes
SmallPtrSet<PHINode*, 16> &DeadPHINodes) {
// Scan the immediate dominators of this block looking for a block which has a
// PHI node for Alloca num. If we find it, mark the PHI node as being alive!
- for (DominatorTree::Node *N = DT[BB]; N; N = N->getIDom()) {
- BasicBlock *DomBB = N->getBlock();
- std::map<BasicBlock*, std::vector<PHINode*> >::iterator
- I = NewPhiNodes.find(DomBB);
- if (I != NewPhiNodes.end() && I->second[AllocaNum]) {
+ DomTreeNode *IDomNode = DT.getNode(BB);
+ for (DomTreeNode *IDom = IDomNode; IDom; IDom = IDom->getIDom()) {
+ BasicBlock *DomBB = IDom->getBlock();
+ DenseMap<std::pair<BasicBlock*, unsigned>, PHINode*>::iterator
+ I = NewPhiNodes.find(std::make_pair(DomBB, AllocaNum));
+ if (I != NewPhiNodes.end()) {
// Ok, we found an inserted PHI node which dominates this value.
- PHINode *DominatingPHI = I->second[AllocaNum];
+ PHINode *DominatingPHI = I->second;
// Find out if we previously thought it was dead. If so, mark it as being
// live by removing it from the DeadPHINodes set.
assert(AI->use_empty() && "Uses of alloca from more than one BB??");
if (AST) AST->deleteValue(AI);
AI->getParent()->getInstList().erase(AI);
+
+ ++NumLocalPromoted;
return false;
}
unsigned &Version,
SmallPtrSet<PHINode*, 16> &InsertedPHINodes) {
// Look up the basic-block in question.
- std::vector<PHINode*> &BBPNs = NewPhiNodes[BB];
- if (BBPNs.empty()) BBPNs.resize(Allocas.size());
+ PHINode *&PN = NewPhiNodes[std::make_pair(BB, AllocaNo)];
// If the BB already has a phi node added for the i'th alloca then we're done!
- if (BBPNs[AllocaNo]) return false;
+ if (PN) return false;
// Create a PhiNode using the dereferenced type... and add the phi-node to the
// BasicBlock.
- PHINode *PN = new PHINode(Allocas[AllocaNo]->getAllocatedType(),
- Allocas[AllocaNo]->getName() + "." +
- utostr(Version++), BB->begin());
- BBPNs[AllocaNo] = PN;
+ PN = new PHINode(Allocas[AllocaNo]->getAllocatedType(),
+ Allocas[AllocaNo]->getName() + "." +
+ utostr(Version++), BB->begin());
+ PhiToAllocaMap[PN] = AllocaNo;
+
InsertedPHINodes.insert(PN);
if (AST && isa<PointerType>(PN->getType()))
// value each Alloca contains on exit from the predecessor block Pred.
//
void PromoteMem2Reg::RenamePass(BasicBlock *BB, BasicBlock *Pred,
- std::vector<Value*> &IncomingVals) {
-
- // If this BB needs a PHI node, update the PHI node for each variable we need
- // PHI nodes for.
- std::map<BasicBlock*, std::vector<PHINode *> >::iterator
- BBPNI = NewPhiNodes.find(BB);
- if (BBPNI != NewPhiNodes.end()) {
- std::vector<PHINode *> &BBPNs = BBPNI->second;
- for (unsigned k = 0; k != BBPNs.size(); ++k)
- if (PHINode *PN = BBPNs[k]) {
- // Add this incoming value to the PHI node.
- PN->addIncoming(IncomingVals[k], Pred);
-
- // The currently active variable for this block is now the PHI.
- IncomingVals[k] = PN;
+ RenamePassData::ValVector &IncomingVals,
+ std::vector<RenamePassData> &Worklist) {
+ // If we are inserting any phi nodes into this BB, they will already be in the
+ // block.
+ if (PHINode *APN = dyn_cast<PHINode>(BB->begin())) {
+ // Pred may have multiple edges to BB. If so, we want to add N incoming
+ // values to each PHI we are inserting on the first time we see the edge.
+ // Check to see if APN already has incoming values from Pred. This also
+ // prevents us from modifying PHI nodes that are not currently being
+ // inserted.
+ bool HasPredEntries = false;
+ for (unsigned i = 0, e = APN->getNumIncomingValues(); i != e; ++i) {
+ if (APN->getIncomingBlock(i) == Pred) {
+ HasPredEntries = true;
+ break;
+ }
+ }
+
+ // If we have PHI nodes to update, compute the number of edges from Pred to
+ // BB.
+ if (!HasPredEntries) {
+ TerminatorInst *PredTerm = Pred->getTerminator();
+ unsigned NumEdges = 0;
+ for (unsigned i = 0, e = PredTerm->getNumSuccessors(); i != e; ++i) {
+ if (PredTerm->getSuccessor(i) == BB)
+ ++NumEdges;
}
+ assert(NumEdges && "Must be at least one edge from Pred to BB!");
+
+ // Add entries for all the phis.
+ BasicBlock::iterator PNI = BB->begin();
+ do {
+ unsigned AllocaNo = PhiToAllocaMap[APN];
+
+ // Add N incoming values to the PHI node.
+ for (unsigned i = 0; i != NumEdges; ++i)
+ APN->addIncoming(IncomingVals[AllocaNo], Pred);
+
+ // The currently active variable for this block is now the PHI.
+ IncomingVals[AllocaNo] = APN;
+
+ // Get the next phi node.
+ ++PNI;
+ APN = dyn_cast<PHINode>(PNI);
+ if (APN == 0) break;
+
+ // Verify it doesn't already have entries for Pred. If it does, it is
+ // not being inserted by this mem2reg invocation.
+ HasPredEntries = false;
+ for (unsigned i = 0, e = APN->getNumIncomingValues(); i != e; ++i) {
+ if (APN->getIncomingBlock(i) == Pred) {
+ HasPredEntries = true;
+ break;
+ }
+ }
+ } while (!HasPredEntries);
+ }
}
-
- // don't revisit nodes
- if (Visited.count(BB)) return;
-
- // mark as visited
- Visited.insert(BB);
+
+ // Don't revisit blocks.
+ if (!Visited.insert(BB)) return;
for (BasicBlock::iterator II = BB->begin(); !isa<TerminatorInst>(II); ) {
Instruction *I = II++; // get the instruction, increment iterator
// Recurse to our successors.
TerminatorInst *TI = BB->getTerminator();
- for (unsigned i = 0; i != TI->getNumSuccessors(); i++) {
- std::vector<Value*> OutgoingVals(IncomingVals);
- RenamePass(TI->getSuccessor(i), BB, OutgoingVals);
- }
+ for (unsigned i = 0; i != TI->getNumSuccessors(); i++)
+ Worklist.push_back(RenamePassData(TI->getSuccessor(i), BB, IncomingVals));
}
/// PromoteMemToReg - Promote the specified list of alloca instructions into
///
void llvm::PromoteMemToReg(const std::vector<AllocaInst*> &Allocas,
DominatorTree &DT, DominanceFrontier &DF,
- const TargetData &TD, AliasSetTracker *AST) {
+ AliasSetTracker *AST) {
// If there is nothing to do, bail out...
if (Allocas.empty()) return;
SmallVector<AllocaInst*, 16> RetryList;
- PromoteMem2Reg(Allocas, RetryList, DT, DF, TD, AST).run();
+ PromoteMem2Reg(Allocas, RetryList, DT, DF, AST).run();
// PromoteMem2Reg may not have been able to promote all of the allocas in one
// pass, run it again if needed.
NewAllocas.assign(RetryList.begin(), RetryList.end());
RetryList.clear();
- PromoteMem2Reg(NewAllocas, RetryList, DT, DF, TD, AST).run();
+ PromoteMem2Reg(NewAllocas, RetryList, DT, DF, AST).run();
NewAllocas.clear();
}
}