#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include <cstdio>
using namespace llvm;
STATISTIC(NumGVNInstr, "Number of instructions deleted");
STATISTIC(NumGVNLoad, "Number of loads deleted");
STATISTIC(NumGVNPRE, "Number of instructions PRE'd");
+STATISTIC(NumGVNBlocks, "Number of blocks merged");
static cl::opt<bool> EnablePRE("enable-pre",
- cl::init(false), cl::Hidden);
+ cl::init(true), cl::Hidden);
//===----------------------------------------------------------------------===//
// ValueTable Class
void erase(Value* v);
unsigned size();
void setAliasAnalysis(AliasAnalysis* A) { AA = A; }
+ AliasAnalysis *getAliasAnalysis() const { return AA; }
void setMemDep(MemoryDependenceAnalysis* M) { MD = M; }
void setDomTree(DominatorTree* D) { DT = D; }
+ uint32_t getNextUnusedValueNumber() { return nextValueNumber; }
};
}
return nextValueNumber++;
}
- Instruction* local_dep = MD->getDependency(C);
+ MemDepResult local_dep = MD->getDependency(C);
- if (local_dep == MemoryDependenceAnalysis::None) {
+ if (local_dep.isNone()) {
valueNumbering.insert(std::make_pair(V, nextValueNumber));
return nextValueNumber++;
- } else if (local_dep != MemoryDependenceAnalysis::NonLocal) {
- if (!isa<CallInst>(local_dep)) {
+ }
+
+ if (Instruction *LocalDepInst = local_dep.getInst()) {
+ if (!isa<CallInst>(LocalDepInst)) {
valueNumbering.insert(std::make_pair(V, nextValueNumber));
return nextValueNumber++;
}
- CallInst* local_cdep = cast<CallInst>(local_dep);
+ CallInst* local_cdep = cast<CallInst>(LocalDepInst);
if (local_cdep->getCalledFunction() != C->getCalledFunction() ||
local_cdep->getNumOperands() != C->getNumOperands()) {
valueNumbering.insert(std::make_pair(V, nextValueNumber));
return nextValueNumber++;
- } else if (!C->getCalledFunction()) {
+ }
+
+ if (!C->getCalledFunction()) {
valueNumbering.insert(std::make_pair(V, nextValueNumber));
return nextValueNumber++;
- } else {
- for (unsigned i = 1; i < C->getNumOperands(); ++i) {
- uint32_t c_vn = lookup_or_add(C->getOperand(i));
- uint32_t cd_vn = lookup_or_add(local_cdep->getOperand(i));
- if (c_vn != cd_vn) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- }
- }
+ }
- uint32_t v = lookup_or_add(local_cdep);
- valueNumbering.insert(std::make_pair(V, v));
- return v;
+ for (unsigned i = 1; i < C->getNumOperands(); ++i) {
+ uint32_t c_vn = lookup_or_add(C->getOperand(i));
+ uint32_t cd_vn = lookup_or_add(local_cdep->getOperand(i));
+ if (c_vn != cd_vn) {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ }
}
- }
+ uint32_t v = lookup_or_add(local_cdep);
+ valueNumbering.insert(std::make_pair(V, v));
+ return v;
+ }
- DenseMap<BasicBlock*, Value*> deps;
- MD->getNonLocalDependency(C, deps);
+
+ const MemoryDependenceAnalysis::NonLocalDepInfo &deps =
+ MD->getNonLocalDependency(C);
CallInst* cdep = 0;
- for (DenseMap<BasicBlock*, Value*>::iterator I = deps.begin(),
- E = deps.end(); I != E; ++I) {
- if (I->second == MemoryDependenceAnalysis::None) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ // Check to see if we have a single dominating call instruction that is
+ // identical to C.
+ for (unsigned i = 0, e = deps.size(); i != e; ++i) {
+ const MemoryDependenceAnalysis::NonLocalDepEntry *I = &deps[i];
+ // Ignore non-local dependencies.
+ if (I->second.isNonLocal())
+ continue;
- return nextValueNumber++;
- } else if (I->second != MemoryDependenceAnalysis::NonLocal) {
- if (DT->properlyDominates(I->first, C->getParent())) {
- if (CallInst* CD = dyn_cast<CallInst>(I->second))
- cdep = CD;
- else {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- }
- } else {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- }
+ // We don't handle non-depedencies. If we already have a call, reject
+ // instruction dependencies.
+ if (I->second.isNone() || cdep != 0) {
+ cdep = 0;
+ break;
+ }
+
+ CallInst *NonLocalDepCall = dyn_cast<CallInst>(I->second.getInst());
+ // FIXME: All duplicated with non-local case.
+ if (NonLocalDepCall && DT->properlyDominates(I->first, C->getParent())){
+ cdep = NonLocalDepCall;
+ continue;
}
+
+ cdep = 0;
+ break;
}
if (!cdep) {
cdep->getNumOperands() != C->getNumOperands()) {
valueNumbering.insert(std::make_pair(V, nextValueNumber));
return nextValueNumber++;
- } else if (!C->getCalledFunction()) {
+ }
+ if (!C->getCalledFunction()) {
valueNumbering.insert(std::make_pair(V, nextValueNumber));
return nextValueNumber++;
- } else {
- for (unsigned i = 1; i < C->getNumOperands(); ++i) {
- uint32_t c_vn = lookup_or_add(C->getOperand(i));
- uint32_t cd_vn = lookup_or_add(cdep->getOperand(i));
- if (c_vn != cd_vn) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- }
+ }
+ for (unsigned i = 1; i < C->getNumOperands(); ++i) {
+ uint32_t c_vn = lookup_or_add(C->getOperand(i));
+ uint32_t cd_vn = lookup_or_add(cdep->getOperand(i));
+ if (c_vn != cd_vn) {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
}
-
- uint32_t v = lookup_or_add(cdep);
- valueNumbering.insert(std::make_pair(V, v));
- return v;
}
+ uint32_t v = lookup_or_add(cdep);
+ valueNumbering.insert(std::make_pair(V, v));
+ return v;
+
} else {
valueNumbering.insert(std::make_pair(V, nextValueNumber));
return nextValueNumber++;
// GVN Pass
//===----------------------------------------------------------------------===//
-namespace llvm {
- template<> struct DenseMapInfo<uint32_t> {
- static inline uint32_t getEmptyKey() { return ~0; }
- static inline uint32_t getTombstoneKey() { return ~0 - 1; }
- static unsigned getHashValue(const uint32_t& Val) { return Val * 37; }
- static bool isPod() { return true; }
- static bool isEqual(const uint32_t& LHS, const uint32_t& RHS) {
- return LHS == RHS;
- }
- };
-}
-
namespace {
struct VISIBILITY_HIDDEN ValueNumberScope {
ValueNumberScope* parent;
bool runOnFunction(Function &F);
public:
static char ID; // Pass identification, replacement for typeid
- GVN() : FunctionPass((intptr_t)&ID) { }
+ GVN() : FunctionPass(&ID) { }
private:
+ MemoryDependenceAnalysis *MD;
+ DominatorTree *DT;
+
ValueTable VN;
DenseMap<BasicBlock*, ValueNumberScope*> localAvail;
// This transformation requires dominator postdominator info
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesCFG();
AU.addRequired<DominatorTree>();
AU.addRequired<MemoryDependenceAnalysis>();
AU.addRequired<AliasAnalysis>();
+
+ AU.addPreserved<DominatorTree>();
AU.addPreserved<AliasAnalysis>();
- AU.addPreserved<MemoryDependenceAnalysis>();
}
// Helper fuctions
bool isSafeReplacement(PHINode* p, Instruction* inst);
bool performPRE(Function& F);
Value* lookupNumber(BasicBlock* BB, uint32_t num);
+ bool mergeBlockIntoPredecessor(BasicBlock* BB);
+ void cleanupGlobalSets();
};
char GVN::ID = 0;
}
Value* GVN::CollapsePhi(PHINode* p) {
- DominatorTree &DT = getAnalysis<DominatorTree>();
Value* constVal = p->hasConstantValue();
-
if (!constVal) return 0;
Instruction* inst = dyn_cast<Instruction>(constVal);
if (!inst)
return constVal;
- if (DT.dominates(inst, p))
+ if (DT->dominates(inst, p))
if (isSafeReplacement(p, inst))
return inst;
return 0;
DenseMap<BasicBlock*, Value*>::iterator V = Phis.find(BB);
if (V != Phis.end() && !top_level) return V->second;
+ // If the block is unreachable, just return undef, since this path
+ // can't actually occur at runtime.
+ if (!DT->isReachableFromEntry(BB))
+ return Phis[BB] = UndefValue::get(orig->getType());
+
BasicBlock* singlePred = BB->getSinglePredecessor();
if (singlePred) {
Value *ret = GetValueForBlock(singlePred, orig, Phis);
PN->addIncoming(val, *PI);
}
- AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
- AA.copyValue(orig, PN);
+ VN.getAliasAnalysis()->copyValue(orig, PN);
// Attempt to collapse PHI nodes that are trivially redundant
Value* v = CollapsePhi(PN);
return PN;
}
- MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
-
- MD.removeInstruction(PN);
PN->replaceAllUsesWith(v);
for (DenseMap<BasicBlock*, Value*>::iterator I = Phis.begin(),
if (I->second == PN)
I->second = v;
+ DEBUG(cerr << "GVN removed: " << *PN);
+ MD->removeInstruction(PN);
PN->eraseFromParent();
Phis[BB] = v;
/// non-local by performing PHI construction.
bool GVN::processNonLocalLoad(LoadInst* L,
SmallVectorImpl<Instruction*> &toErase) {
- MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
-
// Find the non-local dependencies of the load
- DenseMap<BasicBlock*, Value*> deps;
- MD.getNonLocalDependency(L, deps);
+ const MemoryDependenceAnalysis::NonLocalDepInfo &deps =
+ MD->getNonLocalDependency(L);
+ DEBUG(cerr << "INVESTIGATING NONLOCAL LOAD: " << deps.size() << *L);
+#if 0
+ DEBUG(for (unsigned i = 0, e = deps.size(); i != e; ++i) {
+ cerr << " " << deps[i].first->getName();
+ if (Instruction *I = deps[i].second.getInst())
+ cerr << *I;
+ else
+ cerr << "\n";
+ });
+#endif
+
+ // If we had to process more than one hundred blocks to find the
+ // dependencies, this load isn't worth worrying about. Optimizing
+ // it will be too expensive.
+ if (deps.size() > 100)
+ return false;
+
+ BasicBlock *EntryBlock = &L->getParent()->getParent()->getEntryBlock();
DenseMap<BasicBlock*, Value*> repl;
// Filter out useless results (non-locals, etc)
- for (DenseMap<BasicBlock*, Value*>::iterator I = deps.begin(), E = deps.end();
- I != E; ++I) {
- if (I->second == MemoryDependenceAnalysis::None)
- return false;
-
- if (I->second == MemoryDependenceAnalysis::NonLocal)
+ for (unsigned i = 0, e = deps.size(); i != e; ++i) {
+ BasicBlock *DepBB = deps[i].first;
+ MemDepResult DepInfo = deps[i].second;
+
+ if (DepInfo.isNonLocal()) {
+ // If this is a non-local dependency in the entry block, then we depend on
+ // the value live-in at the start of the function. We could insert a load
+ // in the entry block to get this, but for now we'll just bail out.
+ //
+ // FIXME: Consider emitting a load in the entry block to catch this case!
+ // Tricky part is to sink so that it doesn't execute in places where it
+ // isn't needed.
+ if (DepBB == EntryBlock)
+ return false;
continue;
+ }
+
+ if (DepInfo.isNone()) {
+ repl[DepBB] = UndefValue::get(L->getType());
+ continue;
+ }
- if (StoreInst* S = dyn_cast<StoreInst>(I->second)) {
- if (S->getPointerOperand() != L->getPointerOperand())
+ if (StoreInst* S = dyn_cast<StoreInst>(DepInfo.getInst())) {
+ // Reject loads and stores that are to the same address but are of
+ // different types.
+ // NOTE: 403.gcc does have this case (e.g. in readonly_fields_p) because
+ // of bitfield access, it would be interesting to optimize for it at some
+ // point.
+ if (S->getOperand(0)->getType() != L->getType())
return false;
- repl[I->first] = S->getOperand(0);
- } else if (LoadInst* LD = dyn_cast<LoadInst>(I->second)) {
- if (LD->getPointerOperand() != L->getPointerOperand())
+
+ if (S->getPointerOperand() != L->getPointerOperand() &&
+ VN.getAliasAnalysis()->alias(S->getPointerOperand(), 1,
+ L->getPointerOperand(), 1)
+ != AliasAnalysis::MustAlias)
+ return false;
+ repl[DepBB] = S->getOperand(0);
+ } else if (LoadInst* LD = dyn_cast<LoadInst>(DepInfo.getInst())) {
+ if (LD->getType() != L->getType())
return false;
- repl[I->first] = LD;
+
+ if (LD->getPointerOperand() != L->getPointerOperand() &&
+ VN.getAliasAnalysis()->alias(LD->getPointerOperand(), 1,
+ L->getPointerOperand(), 1)
+ != AliasAnalysis::MustAlias)
+ return false;
+ repl[DepBB] = LD;
} else {
return false;
}
for (SmallPtrSet<Instruction*, 4>::iterator I = p.begin(), E = p.end();
I != E; ++I) {
if ((*I)->getParent() == L->getParent()) {
- MD.removeInstruction(L);
L->replaceAllUsesWith(*I);
toErase.push_back(L);
NumGVNLoad++;
repl.insert(std::make_pair((*I)->getParent(), *I));
}
-
+
+ DEBUG(cerr << "GVN REMOVING NONLOCAL LOAD: " << *L);
+
// Perform PHI construction
SmallPtrSet<BasicBlock*, 4> visited;
Value* v = GetValueForBlock(L->getParent(), L, repl, true);
-
- MD.removeInstruction(L);
L->replaceAllUsesWith(v);
toErase.push_back(L);
NumGVNLoad++;
-
return true;
}
LoadInst*& last = lastLoad[pointer];
// ... to a pointer that has been loaded from before...
- MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
bool removedNonLocal = false;
- Instruction* dep = MD.getDependency(L);
- if (dep == MemoryDependenceAnalysis::NonLocal &&
+ MemDepResult dep = MD->getDependency(L);
+ if (dep.isNonLocal() &&
L->getParent() != &L->getParent()->getParent()->getEntryBlock()) {
removedNonLocal = processNonLocalLoad(L, toErase);
// Walk up the dependency chain until we either find
// a dependency we can use, or we can't walk any further
- while (dep != MemoryDependenceAnalysis::None &&
- dep != MemoryDependenceAnalysis::NonLocal &&
- (isa<LoadInst>(dep) || isa<StoreInst>(dep))) {
+ while (Instruction *DepInst = dep.getInst()) {
// ... that depends on a store ...
- if (StoreInst* S = dyn_cast<StoreInst>(dep)) {
+ if (StoreInst* S = dyn_cast<StoreInst>(DepInst)) {
if (S->getPointerOperand() == pointer) {
// Remove it!
- MD.removeInstruction(L);
-
L->replaceAllUsesWith(S->getOperand(0));
toErase.push_back(L);
deletedLoad = true;
// Whether we removed it or not, we can't
// go any further
break;
+ } else if (!isa<LoadInst>(DepInst)) {
+ // Only want to handle loads below.
+ break;
} else if (!last) {
// If we don't depend on a store, and we haven't
// been loaded before, bail.
break;
- } else if (dep == last) {
+ } else if (DepInst == last) {
// Remove it!
- MD.removeInstruction(L);
-
L->replaceAllUsesWith(last);
toErase.push_back(L);
deletedLoad = true;
NumGVNLoad++;
-
break;
} else {
- dep = MD.getDependency(L, dep);
+ dep = MD->getDependencyFrom(L, DepInst, DepInst->getParent());
}
}
- if (dep != MemoryDependenceAnalysis::None &&
- dep != MemoryDependenceAnalysis::NonLocal &&
- isa<AllocationInst>(dep)) {
- // Check that this load is actually from the
- // allocation we found
- Value* v = L->getOperand(0);
- while (true) {
- if (BitCastInst *BC = dyn_cast<BitCastInst>(v))
- v = BC->getOperand(0);
- else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(v))
- v = GEP->getOperand(0);
- else
- break;
- }
- if (v == dep) {
- // If this load depends directly on an allocation, there isn't
- // anything stored there; therefore, we can optimize this load
- // to undef.
- MD.removeInstruction(L);
-
- L->replaceAllUsesWith(UndefValue::get(L->getType()));
- toErase.push_back(L);
- deletedLoad = true;
- NumGVNLoad++;
- }
+ // If this load really doesn't depend on anything, then we must be loading an
+ // undef value. This can happen when loading for a fresh allocation with no
+ // intervening stores, for example.
+ if (dep.isNone()) {
+ // If this load depends directly on an allocation, there isn't
+ // anything stored there; therefore, we can optimize this load
+ // to undef.
+ L->replaceAllUsesWith(UndefValue::get(L->getType()));
+ toErase.push_back(L);
+ deletedLoad = true;
+ NumGVNLoad++;
}
if (!deletedLoad)
}
Value* GVN::lookupNumber(BasicBlock* BB, uint32_t num) {
- ValueNumberScope* locals = localAvail[BB];
+ DenseMap<BasicBlock*, ValueNumberScope*>::iterator I = localAvail.find(BB);
+ if (I == localAvail.end())
+ return 0;
+
+ ValueNumberScope* locals = I->second;
while (locals) {
DenseMap<uint32_t, Value*>::iterator I = locals->table.find(num);
return changed;
}
+ uint32_t nextNum = VN.getNextUnusedValueNumber();
unsigned num = VN.lookup_or_add(I);
// Allocations are always uniquely numbered, so we can save time and memory
// by fast failing them.
- if (isa<AllocationInst>(I)) {
+ if (isa<AllocationInst>(I) || isa<TerminatorInst>(I)) {
localAvail[I->getParent()]->table.insert(std::make_pair(num, I));
return false;
}
} else {
localAvail[I->getParent()]->table.insert(std::make_pair(num, I));
}
+
+ // If the number we were assigned was a brand new VN, then we don't
+ // need to do a lookup to see if the number already exists
+ // somewhere in the domtree: it can't!
+ } else if (num == nextNum) {
+ localAvail[I->getParent()]->table.insert(std::make_pair(num, I));
+
// Perform value-number based elimination
} else if (Value* repl = lookupNumber(I->getParent(), num)) {
// Remove it!
- MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
- MD.removeInstruction(I);
-
VN.erase(I);
I->replaceAllUsesWith(repl);
toErase.push_back(I);
return true;
- } else if (!I->isTerminator()) {
+ } else {
localAvail[I->getParent()]->table.insert(std::make_pair(num, I));
}
// function.
//
bool GVN::runOnFunction(Function& F) {
+ MD = &getAnalysis<MemoryDependenceAnalysis>();
+ DT = &getAnalysis<DominatorTree>();
VN.setAliasAnalysis(&getAnalysis<AliasAnalysis>());
- VN.setMemDep(&getAnalysis<MemoryDependenceAnalysis>());
- VN.setDomTree(&getAnalysis<DominatorTree>());
+ VN.setMemDep(MD);
+ VN.setDomTree(DT);
bool changed = false;
bool shouldContinue = true;
+ // Merge unconditional branches, allowing PRE to catch more
+ // optimization opportunities.
+ for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ) {
+ BasicBlock* BB = FI;
+ ++FI;
+ bool removedBlock = MergeBlockIntoPredecessor(BB, this);
+ if (removedBlock) NumGVNBlocks++;
+
+ changed |= removedBlock;
+ }
+
while (shouldContinue) {
shouldContinue = iterateOnFunction(F);
changed |= shouldContinue;
}
+ if (EnablePRE) {
+ bool PREChanged = true;
+ while (PREChanged) {
+ PREChanged = performPRE(F);
+ changed |= PREChanged;
+ }
+ }
+
+ cleanupGlobalSets();
+
return changed;
}
bool GVN::processBlock(DomTreeNode* DTN) {
BasicBlock* BB = DTN->getBlock();
-
SmallVector<Instruction*, 8> toErase;
DenseMap<Value*, LoadInst*> lastSeenLoad;
bool changed_function = false;
--BI;
for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
- E = toErase.end(); I != E; ++I)
+ E = toErase.end(); I != E; ++I) {
+ DEBUG(cerr << "GVN removed: " << **I);
+ MD->removeInstruction(*I);
(*I)->eraseFromParent();
+ }
if (AtStart)
BI = BB->begin();
/// performPRE - Perform a purely local form of PRE that looks for diamond
/// control flow patterns and attempts to perform simple PRE at the join point.
bool GVN::performPRE(Function& F) {
- bool changed = false;
+ bool Changed = false;
SmallVector<std::pair<TerminatorInst*, unsigned>, 4> toSplit;
+ DenseMap<BasicBlock*, Value*> predMap;
for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
BasicBlock* CurrentBlock = *DI;
for (BasicBlock::iterator BI = CurrentBlock->begin(),
BE = CurrentBlock->end(); BI != BE; ) {
- if (isa<AllocaInst>(BI) || isa<TerminatorInst>(BI) ||
- isa<LoadInst>(BI) || isa<StoreInst>(BI) ||
- isa<CallInst>(BI) || isa<PHINode>(BI)) {
- BI++;
+ Instruction *CurInst = BI++;
+
+ if (isa<AllocationInst>(CurInst) || isa<TerminatorInst>(CurInst) ||
+ isa<PHINode>(CurInst) || CurInst->mayReadFromMemory() ||
+ CurInst->mayWriteToMemory())
continue;
- }
- uint32_t valno = VN.lookup(BI);
+ uint32_t valno = VN.lookup(CurInst);
// Look for the predecessors for PRE opportunities. We're
// only trying to solve the basic diamond case, where
unsigned numWith = 0;
unsigned numWithout = 0;
BasicBlock* PREPred = 0;
- DenseMap<BasicBlock*, Value*> predMap;
+ predMap.clear();
+
for (pred_iterator PI = pred_begin(CurrentBlock),
PE = pred_end(CurrentBlock); PI != PE; ++PI) {
// We're not interested in PRE where the block is its
if (predV == localAvail[*PI]->table.end()) {
PREPred = *PI;
numWithout++;
- } else if (predV->second == BI) {
+ } else if (predV->second == CurInst) {
numWithout = 2;
} else {
predMap[*PI] = predV->second;
// Don't do PRE when it might increase code size, i.e. when
// we would need to insert instructions in more than one pred.
- if (numWithout != 1 || numWith == 0) {
- BI++;
+ if (numWithout != 1 || numWith == 0)
continue;
- }
// We can't do PRE safely on a critical edge, so instead we schedule
// the edge to be split and perform the PRE the next time we iterate
unsigned succNum = 0;
for (unsigned i = 0, e = PREPred->getTerminator()->getNumSuccessors();
i != e; ++i)
- if (PREPred->getTerminator()->getSuccessor(i) == PREPred) {
+ if (PREPred->getTerminator()->getSuccessor(i) == CurrentBlock) {
succNum = i;
break;
}
if (isCriticalEdge(PREPred->getTerminator(), succNum)) {
toSplit.push_back(std::make_pair(PREPred->getTerminator(), succNum));
- changed = true;
- BI++;
+ Changed = true;
continue;
}
// will be available in the predecessor by the time we need them. Any
// that weren't original present will have been instantiated earlier
// in this loop.
- Instruction* PREInstr = BI->clone();
+ Instruction* PREInstr = CurInst->clone();
bool success = true;
- for (unsigned i = 0; i < BI->getNumOperands(); ++i) {
- Value* op = BI->getOperand(i);
- if (isa<Argument>(op) || isa<Constant>(op) || isa<GlobalValue>(op))
- PREInstr->setOperand(i, op);
- else if (!lookupNumber(PREPred, VN.lookup(op))) {
+ for (unsigned i = 0, e = CurInst->getNumOperands(); i != e; ++i) {
+ Value *Op = PREInstr->getOperand(i);
+ if (isa<Argument>(Op) || isa<Constant>(Op) || isa<GlobalValue>(Op))
+ continue;
+
+ if (Value *V = lookupNumber(PREPred, VN.lookup(Op))) {
+ PREInstr->setOperand(i, V);
+ } else {
success = false;
break;
- } else
- PREInstr->setOperand(i, lookupNumber(PREPred, VN.lookup(op)));
+ }
}
// Fail out if we encounter an operand that is not available in
// are not value numbered precisely.
if (!success) {
delete PREInstr;
- BI++;
continue;
}
PREInstr->insertBefore(PREPred->getTerminator());
- PREInstr->setName(BI->getName() + ".pre");
+ PREInstr->setName(CurInst->getName() + ".pre");
predMap[PREPred] = PREInstr;
VN.add(PREInstr, valno);
NumGVNPRE++;
localAvail[PREPred]->table.insert(std::make_pair(valno, PREInstr));
// Create a PHI to make the value available in this block.
- PHINode* Phi = PHINode::Create(BI->getType(),
- BI->getName() + ".pre-phi",
+ PHINode* Phi = PHINode::Create(CurInst->getType(),
+ CurInst->getName() + ".pre-phi",
CurrentBlock->begin());
for (pred_iterator PI = pred_begin(CurrentBlock),
PE = pred_end(CurrentBlock); PI != PE; ++PI)
Phi->addIncoming(predMap[*PI], *PI);
VN.add(Phi, valno);
-
- // The newly created PHI completely replaces the old instruction,
- // so we need to update the maps to reflect this.
- DomTreeNode* DTN = getAnalysis<DominatorTree>()[CurrentBlock];
- for (DomTreeNode::iterator UI = DTN->begin(), UE = DTN->end();
- UI != UE; ++UI)
- localAvail[(*UI)->getBlock()]->table[valno] = Phi;
localAvail[CurrentBlock]->table[valno] = Phi;
- BI->replaceAllUsesWith(Phi);
- VN.erase(BI);
-
- Instruction* erase = BI;
- BI++;
- erase->eraseFromParent();
+ CurInst->replaceAllUsesWith(Phi);
+ VN.erase(CurInst);
- changed = true;
+ DEBUG(cerr << "GVN PRE removed: " << *CurInst);
+ MD->removeInstruction(CurInst);
+ CurInst->eraseFromParent();
+ Changed = true;
}
}
for (SmallVector<std::pair<TerminatorInst*, unsigned>, 4>::iterator
- I = toSplit.begin(), E = toSplit.end(); I != E; ++I)
+ I = toSplit.begin(), E = toSplit.end(); I != E; ++I) {
SplitCriticalEdge(I->first, I->second, this);
+ BasicBlock* NewBlock = I->first->getSuccessor(I->second);
+ localAvail[NewBlock] =
+ new ValueNumberScope(localAvail[I->first->getParent()]);
+ }
- return changed;
+ return Changed;
}
-// GVN::iterateOnFunction - Executes one iteration of GVN
+// iterateOnFunction - Executes one iteration of GVN
bool GVN::iterateOnFunction(Function &F) {
- // Clean out global sets from any previous functions
- VN.clear();
- phiMap.clear();
-
- for (DenseMap<BasicBlock*, ValueNumberScope*>::iterator
- I = localAvail.begin(), E = localAvail.end(); I != E; ++I)
- delete I->second;
- localAvail.clear();
-
- DominatorTree &DT = getAnalysis<DominatorTree>();
+ cleanupGlobalSets();
// Top-down walk of the dominator tree
bool changed = false;
- for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
- DE = df_end(DT.getRootNode()); DI != DE; ++DI)
+ for (df_iterator<DomTreeNode*> DI = df_begin(DT->getRootNode()),
+ DE = df_end(DT->getRootNode()); DI != DE; ++DI)
changed |= processBlock(*DI);
- if (!EnablePRE)
- changed |= performPRE(F);
-
return changed;
}
+
+void GVN::cleanupGlobalSets() {
+ VN.clear();
+ phiMap.clear();
+
+ for (DenseMap<BasicBlock*, ValueNumberScope*>::iterator
+ I = localAvail.begin(), E = localAvail.end(); I != E; ++I)
+ delete I->second;
+ localAvail.clear();
+}
projects / oota-llvm.git / blobdiff