#include "llvm/Value.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/ScopedHashTable.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/SparseBitVector.h"
}
//===----------------------------------------------------------------------===//
-// ValueNumberedSet Class
+// GVN Pass
//===----------------------------------------------------------------------===//
-namespace {
-class VISIBILITY_HIDDEN ValueNumberedSet {
- private:
- SmallPtrSet<Value*, 8> contents;
- SparseBitVector<64> numbers;
- public:
- ValueNumberedSet() { }
- ValueNumberedSet(const ValueNumberedSet& other) {
- numbers = other.numbers;
- contents = other.contents;
- }
-
- typedef SmallPtrSet<Value*, 8>::iterator iterator;
-
- iterator begin() { return contents.begin(); }
- iterator end() { return contents.end(); }
-
- bool insert(Value* v) { return contents.insert(v); }
- void insert(iterator I, iterator E) { contents.insert(I, E); }
- void erase(Value* v) { contents.erase(v); }
- unsigned count(Value* v) { return contents.count(v); }
- size_t size() { return contents.size(); }
-
- void set(unsigned i) {
- numbers.set(i);
- }
-
- void operator=(const ValueNumberedSet& other) {
- contents = other.contents;
- numbers = other.numbers;
- }
-
- void reset(unsigned i) {
- numbers.reset(i);
- }
-
- bool test(unsigned i) {
- return numbers.test(i);
+
+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; }
+ static bool isPod() { return true; }
+ static bool isEqual(const uint32_t& LHS, const uint32_t& RHS) {
+ return LHS == RHS;
}
-};
+ };
}
-//===----------------------------------------------------------------------===//
-// GVN Pass
-//===----------------------------------------------------------------------===//
+typedef ScopedHashTable<uint32_t, Value*> ValueNumberMap;
+typedef ScopedHashTableScope<uint32_t, Value*> ValueNumberScope;
namespace {
private:
ValueTable VN;
- DenseMap<BasicBlock*, ValueNumberedSet> availableOut;
+ DenseMap<BasicBlock*, ValueNumberScope> availableOut;
+ ValueNumberMap BaseMap;
typedef DenseMap<Value*, SmallPtrSet<Instruction*, 4> > PhiMapType;
PhiMapType phiMap;
// Helper fuctions
// FIXME: eliminate or document these better
- Value* find_leader(ValueNumberedSet& vals, uint32_t v) ;
- void val_insert(ValueNumberedSet& s, Value* v);
bool processLoad(LoadInst* L,
DenseMap<Value*, LoadInst*> &lastLoad,
SmallVectorImpl<Instruction*> &toErase);
bool processInstruction(Instruction* I,
- ValueNumberedSet& currAvail,
DenseMap<Value*, LoadInst*>& lastSeenLoad,
SmallVectorImpl<Instruction*> &toErase);
bool processNonLocalLoad(LoadInst* L,
SmallVectorImpl<Instruction*> &toErase);
+ bool processBlock(DomTreeNode* DTN);
Value *GetValueForBlock(BasicBlock *BB, LoadInst* orig,
DenseMap<BasicBlock*, Value*> &Phis,
bool top_level = false);
static RegisterPass<GVN> X("gvn",
"Global Value Numbering");
-/// find_leader - Given a set and a value number, return the first
-/// element of the set with that value number, or 0 if no such element
-/// is present
-Value* GVN::find_leader(ValueNumberedSet& vals, uint32_t v) {
- if (!vals.test(v))
- return 0;
-
- for (ValueNumberedSet::iterator I = vals.begin(), E = vals.end();
- I != E; ++I)
- if (v == VN.lookup(*I))
- return *I;
-
- assert(0 && "No leader found, but present bit is set?");
- return 0;
-}
-
-/// val_insert - Insert a value into a set only if there is not a value
-/// with the same value number already in the set
-void GVN::val_insert(ValueNumberedSet& s, Value* v) {
- uint32_t num = VN.lookup(v);
- if (!s.test(num))
- s.insert(v);
-}
-
void GVN::dump(DenseMap<BasicBlock*, Value*>& d) {
printf("{\n");
for (DenseMap<BasicBlock*, Value*>::iterator I = d.begin(),
/// processInstruction - When calculating availability, handle an instruction
/// by inserting it into the appropriate sets
-bool GVN::processInstruction(Instruction *I, ValueNumberedSet &currAvail,
+bool GVN::processInstruction(Instruction *I,
DenseMap<Value*, LoadInst*> &lastSeenLoad,
SmallVectorImpl<Instruction*> &toErase) {
if (LoadInst* L = dyn_cast<LoadInst>(I))
toErase.push_back(p);
}
// Perform value-number based elimination
- } else if (currAvail.test(num)) {
- Value* repl = find_leader(currAvail, num);
+ } else if (BaseMap.begin(num) != BaseMap.end()) {
+ Value* repl = *BaseMap.begin(num);
// Remove it!
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
toErase.push_back(I);
return true;
} else if (!I->isTerminator()) {
- currAvail.set(num);
- currAvail.insert(I);
+ BaseMap.insert(num, I);
}
return false;
}
+bool GVN::processBlock(DomTreeNode* DTN) {
+ BasicBlock* BB = DTN->getBlock();
+ ValueNumberScope NewScope(BaseMap);
+
+ SmallVector<Instruction*, 8> toErase;
+ DenseMap<Value*, LoadInst*> lastSeenLoad;
+ bool changed_function = false;
+
+ for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
+ BI != BE;) {
+ changed_function |= processInstruction(BI, lastSeenLoad, toErase);
+ if (toErase.empty()) {
+ ++BI;
+ continue;
+ }
+
+ // If we need some instructions deleted, do it now.
+ NumGVNInstr += toErase.size();
+
+ // Avoid iterator invalidation.
+ bool AtStart = BI == BB->begin();
+ if (!AtStart)
+ --BI;
+
+ for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
+ E = toErase.end(); I != E; ++I)
+ (*I)->eraseFromParent();
+
+ if (AtStart)
+ BI = BB->begin();
+ else
+ ++BI;
+
+ toErase.clear();
+ }
+
+ for (DomTreeNode::iterator I = DTN->begin(), E = DTN->end(); I != E; ++I)
+ changed_function |= processBlock(*I);
+
+ return changed_function;
+}
+
// GVN::iterateOnFunction - Executes one iteration of GVN
bool GVN::iterateOnFunction(Function &F) {
// Clean out global sets from any previous functions
VN.clear();
availableOut.clear();
phiMap.clear();
-
- bool changed_function = false;
DominatorTree &DT = getAnalysis<DominatorTree>();
-
- SmallVector<Instruction*, 8> toErase;
- DenseMap<Value*, LoadInst*> lastSeenLoad;
- DenseMap<DomTreeNode*, size_t> numChildrenVisited;
// Top-down walk of the dominator tree
- for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
- E = df_end(DT.getRootNode()); DI != E; ++DI) {
-
- // Get the set to update for this block
- ValueNumberedSet& currAvail = availableOut[DI->getBlock()];
- lastSeenLoad.clear();
-
- BasicBlock* BB = DI->getBlock();
-
- // A block inherits AVAIL_OUT from its dominator
- if (DI->getIDom() != 0) {
- currAvail = availableOut[DI->getIDom()->getBlock()];
-
- numChildrenVisited[DI->getIDom()]++;
-
- if (numChildrenVisited[DI->getIDom()] == DI->getIDom()->getNumChildren()) {
- availableOut.erase(DI->getIDom()->getBlock());
- numChildrenVisited.erase(DI->getIDom());
- }
- }
-
- for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
- BI != BE;) {
- changed_function |= processInstruction(BI, currAvail,
- lastSeenLoad, toErase);
- if (toErase.empty()) {
- ++BI;
- continue;
- }
-
- // If we need some instructions deleted, do it now.
- NumGVNInstr += toErase.size();
-
- // Avoid iterator invalidation.
- bool AtStart = BI == BB->begin();
- if (!AtStart)
- --BI;
-
- for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
- E = toErase.end(); I != E; ++I)
- (*I)->eraseFromParent();
-
- if (AtStart)
- BI = BB->begin();
- else
- ++BI;
-
- toErase.clear();
- }
- }
-
- return changed_function;
+ return processBlock(DT.getRootNode());
}
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