[llvm-commits] CVS: llvm/lib/Analysis/AliasSetTracker.cpp
Chris Lattner
lattner at cs.uiuc.edu
Mon Feb 24 14:39:02 PST 2003
Changes in directory llvm/lib/Analysis:
AliasSetTracker.cpp updated: 1.1 -> 1.2
---
Log message:
This is a substantial rewrite of the AliasSetTracker class which now uses
a union-find based algorithm, is significantly faster, and is more general.
It will also scale to handle call instructions correctly, which is a nice
added bonus.
This includes a new pass -print-alias-sets which can be used to show how
alias sets are formed for a particular analysis.
---
Diffs of the changes:
Index: llvm/lib/Analysis/AliasSetTracker.cpp
diff -u llvm/lib/Analysis/AliasSetTracker.cpp:1.1 llvm/lib/Analysis/AliasSetTracker.cpp:1.2
--- llvm/lib/Analysis/AliasSetTracker.cpp:1.1 Thu Sep 26 16:49:07 2002
+++ llvm/lib/Analysis/AliasSetTracker.cpp Mon Feb 24 14:37:56 2003
@@ -9,164 +9,271 @@
#include "llvm/iMemory.h"
#include "llvm/iOther.h"
#include "llvm/iTerminators.h"
+#include "llvm/Pass.h"
+#include "llvm/Assembly/Writer.h"
+#include "llvm/Support/InstIterator.h"
-/// updateAccessTypes - Depending on what type of accesses are in this set,
-/// decide whether the set contains just references, just modifications, or a
-/// mix.
+/// mergeSetIn - Merge the specified alias set into this alias set...
///
-void AliasSet::updateAccessType() {
- if (!Calls.empty() || !Invokes.empty()) {
- AccessTy = ModRef;
- } else if (!Loads.empty()) {
- if (Stores.empty())
- AccessTy = Refs;
- else
- AccessTy = ModRef;
- } else {
- AccessTy = Mods;
+void AliasSet::mergeSetIn(AliasSet &AS) {
+ assert(!AS.Forward && "Alias set is already forwarding!");
+ assert(!Forward && "This set is a forwarding set!!");
+
+ // Update the alias and access types of this set...
+ AccessTy |= AS.AccessTy;
+ AliasTy |= AS.AliasTy;
+
+ if (CallSites.empty()) { // Merge call sites...
+ if (!AS.CallSites.empty())
+ std::swap(CallSites, AS.CallSites);
+ } else if (!AS.CallSites.empty()) {
+ CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end());
+ AS.CallSites.clear();
}
+
+ // FIXME: If AS's refcount is zero, nuke it now...
+ assert(RefCount != 0);
+
+ AS.Forward = this; // Forward across AS now...
+ RefCount++; // AS is now pointing to us...
+
+ // Merge the list of constituent pointers...
+ PtrListTail->second.setTail(AS.PtrListHead);
+ PtrListTail = AS.PtrListTail;
+ AS.PtrListHead = AS.PtrListTail = 0;
}
-/// mergeSetIn - Merge the specified alias set into this alias set...
-///
-void AliasSet::mergeSetIn(const AliasSet &AS) {
- // Merge instruction sets...
- Loads.insert( Loads.end(), AS.Loads.begin() , AS.Loads.end());
- Stores.insert( Stores.end(), AS.Stores.begin() , AS.Stores.end());
- Calls.insert( Calls.end(), AS.Calls.begin() , AS.Calls.end());
- Invokes.insert(Invokes.end(), AS.Invokes.begin(), AS.Invokes.end());
+void AliasSetTracker::removeAliasSet(AliasSet *AS) {
+ AliasSets.erase(AS);
+}
- // Update the alias and access types of this set...
- if (AS.getAliasType() == MayAlias)
- AliasTy = MayAlias;
- updateAccessType();
+void AliasSet::removeFromTracker(AliasSetTracker &AST) {
+ assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
+ AST.removeAliasSet(this);
+}
+
+void AliasSet::addPointer(AliasSetTracker &AST, HashNodePair &Entry){
+ assert(!Entry.second.hasAliasSet() && "Entry already in set!");
+
+ AliasAnalysis &AA = AST.getAliasAnalysis();
+
+ if (isMustAlias()) // Check to see if we have to downgrade to _may_ alias
+ if (Value *V = getSomePointer())
+ if (AA.alias(V, Entry.first) == AliasAnalysis::MayAlias)
+ AliasTy = MayAlias;
+
+ Entry.second.setAliasSet(this);
+
+ // Add it to the end of the list...
+ if (PtrListTail)
+ PtrListTail->second.setTail(&Entry);
+ else
+ PtrListHead = &Entry;
+ PtrListTail = &Entry;
+ RefCount++; // Entry points to alias set...
+}
+
+void AliasSet::addCallSite(CallSite CS) {
+ CallSites.push_back(CS);
+ AliasTy = MayAlias; // FIXME: Too conservative
}
-/// pointerAliasesSet - Return true if the specified pointer "may" (or must)
+/// aliasesPointer - Return true if the specified pointer "may" (or must)
/// alias one of the members in the set.
///
-bool AliasSet::pointerAliasesSet(const Value *Ptr, AliasAnalysis &AA) const {
- if (!Calls.empty() || !Invokes.empty())
- return true;
- for (unsigned i = 0, e = Loads.size(); i != e; ++i)
- if (AA.alias(Ptr, Loads[i]->getOperand(0)))
- return true;
- for (unsigned i = 0, e = Stores.size(); i != e; ++i)
- if (AA.alias(Ptr, Stores[i]->getOperand(1)))
+bool AliasSet::aliasesPointer(const Value *Ptr, AliasAnalysis &AA) const {
+ if (AliasTy == MustAlias) {
+ assert(CallSites.empty() && "Illegal must alias set!");
+
+ // If this is a set of MustAliases, only check to see if the pointer aliases
+ // SOME value in the set...
+ Value *SomePtr = getSomePointer();
+ assert(SomePtr && "Empty must-alias set??");
+ return AA.alias(SomePtr, Ptr);
+ }
+
+ // If this is a may-alias set, we have to check all of the pointers in the set
+ // to be sure it doesn't alias the set...
+ for (iterator I = begin(), E = end(); I != E; ++I)
+ if (AA.alias(Ptr, *I))
return true;
+
+ // Check the call sites list and invoke list...
+ if (!CallSites.empty())
+ // FIXME: this is pessimistic!
+ return true;
+
return false;
}
-/// getSomePointer - This method may only be called when the AliasType of the
-/// set is MustAlias. This is used to return any old pointer (which must alias
-/// all other pointers in the set) so that the caller can decide whether to turn
-/// this set into a may alias set or not.
-///
-Value *AliasSet::getSomePointer() const {
- assert(getAliasType() == MustAlias &&
- "Cannot call getSomePointer on a 'MayAlias' set!");
- assert(Calls.empty() && Invokes.empty() && "Call/invokes mean may alias!");
-
- if (!Loads.empty())
- return Loads[0]->getOperand(0);
- assert(!Stores.empty() && "There are no instructions in this set!");
- return Stores[0]->getOperand(1);
+bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
+ // FIXME: Too conservative!
+ return true;
}
-
/// findAliasSetForPointer - Given a pointer, find the one alias set to put the
/// instruction referring to the pointer into. If there are multiple alias sets
/// that may alias the pointer, merge them together and return the unified set.
///
AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr) {
AliasSet *FoundSet = 0;
- for (unsigned i = 0; i != AliasSets.size(); ++i) {
- if (AliasSets[i].pointerAliasesSet(Ptr, AA)) {
+ for (iterator I = begin(), E = end(); I != E; ++I)
+ if (I->aliasesPointer(Ptr, AA)) {
if (FoundSet == 0) { // If this is the first alias set ptr can go into...
- FoundSet = &AliasSets[i]; // Remember it.
+ FoundSet = I; // Remember it.
} else { // Otherwise, we must merge the sets...
- FoundSet->mergeSetIn(AliasSets[i]); // Merge in contents...
- AliasSets.erase(AliasSets.begin()+i); // Remove the set...
- --i; // Don't skip the next set
+ FoundSet->mergeSetIn(*I); // Merge in contents...
+ }
+ }
+
+ return FoundSet;
+}
+
+AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
+ AliasSet *FoundSet = 0;
+ for (iterator I = begin(), E = end(); I != E; ++I)
+ if (I->aliasesCallSite(CS, AA)) {
+ if (FoundSet == 0) { // If this is the first alias set ptr can go into...
+ FoundSet = I; // Remember it.
+ } else { // Otherwise, we must merge the sets...
+ FoundSet->mergeSetIn(*I); // Merge in contents...
}
}
- }
return FoundSet;
}
-void AliasSetTracker::add(LoadInst *LI) {
- Value *Pointer = LI->getOperand(0);
- // Check to see if the loaded pointer aliases any sets...
- AliasSet *AS = findAliasSetForPointer(Pointer);
- if (AS) {
- AS->Loads.push_back(LI);
- // Check to see if we need to change this into a MayAlias set now...
- if (AS->getAliasType() == AliasSet::MustAlias)
- if (AA.alias(AS->getSomePointer(), Pointer) != AliasAnalysis::MustAlias)
- AS->AliasTy = AliasSet::MayAlias;
- AS->updateAccessType();
+
+/// getAliasSetForPointer - Return the alias set that the specified pointer
+/// lives in...
+AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer) {
+ AliasSet::HashNodePair &Entry = getEntryFor(Pointer);
+
+ // Check to see if the pointer is already known...
+ if (Entry.second.hasAliasSet()) {
+ // Return the set!
+ return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this);
+ } else if (AliasSet *AS = findAliasSetForPointer(Pointer)) {
+ // Add it to the alias set it aliases...
+ AS->addPointer(*this, Entry);
+ return *AS;
} else {
- // Otherwise create a new alias set to hold the load...
+ // Otherwise create a new alias set to hold the loaded pointer...
AliasSets.push_back(AliasSet());
- AliasSets.back().Loads.push_back(LI);
- AliasSets.back().AccessTy = AliasSet::Refs;
+ AliasSets.back().addPointer(*this, Entry);
+ return AliasSets.back();
}
}
+void AliasSetTracker::add(LoadInst *LI) {
+ addPointer(LI->getOperand(0), AliasSet::Refs);
+}
+
void AliasSetTracker::add(StoreInst *SI) {
- Value *Pointer = SI->getOperand(1);
+ addPointer(SI->getOperand(1), AliasSet::Mods);
+}
- // Check to see if the loaded pointer aliases any sets...
- AliasSet *AS = findAliasSetForPointer(Pointer);
- if (AS) {
- AS->Stores.push_back(SI);
- // Check to see if we need to change this into a MayAlias set now...
- if (AS->getAliasType() == AliasSet::MustAlias)
- if (AA.alias(AS->getSomePointer(), Pointer) != AliasAnalysis::MustAlias)
- AS->AliasTy = AliasSet::MayAlias;
- AS->updateAccessType();
- } else {
- // Otherwise create a new alias set to hold the load...
+void AliasSetTracker::add(CallSite CS) {
+ AliasSet *AS = findAliasSetForCallSite(CS);
+ if (!AS) {
AliasSets.push_back(AliasSet());
- AliasSets.back().Stores.push_back(SI);
- AliasSets.back().AccessTy = AliasSet::Mods;
+ AS = &AliasSets.back();
}
+ AS->addCallSite(CS);
}
+void AliasSetTracker::add(Instruction *I) {
+ // Dispatch to one of the other add methods...
+ if (LoadInst *LI = dyn_cast<LoadInst>(I))
+ add(LI);
+ else if (StoreInst *SI = dyn_cast<StoreInst>(I))
+ add(SI);
+ else if (CallInst *CI = dyn_cast<CallInst>(I))
+ add(CI);
+ else if (InvokeInst *II = dyn_cast<InvokeInst>(I))
+ add(II);
+}
-void AliasSetTracker::mergeAllSets() {
- if (AliasSets.size() < 2) return; // Noop
+//===----------------------------------------------------------------------===//
+// AliasSet/AliasSetTracker Printing Support
+//===----------------------------------------------------------------------===//
+
+void AliasSet::print(std::ostream &OS) const {
+ OS << " AliasSet[" << (void*)this << "," << RefCount << "] ";
+ OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, ";
+ switch (AccessTy) {
+ case NoModRef: OS << "No access "; break;
+ case Refs : OS << "Ref "; break;
+ case Mods : OS << "Mod "; break;
+ case ModRef : OS << "Mod/Ref "; break;
+ default: assert(0 && "Bad value for AccessTy!");
+ }
+ if (Forward)
+ OS << " forwarding to " << (void*)Forward;
- // Merge all of the sets into set #0
- for (unsigned i = 1, e = AliasSets.size(); i != e; ++i)
- AliasSets[0].mergeSetIn(AliasSets[i]);
- // Delete extraneous sets...
- AliasSets.erase(AliasSets.begin()+1, AliasSets.end());
+ if (begin() != end()) {
+ OS << "Pointers: ";
+ for (iterator I = begin(), E = end(); I != E; ++I) {
+ if (I != begin()) OS << ", ";
+ WriteAsOperand(OS, *I);
+ }
+ }
+ if (!CallSites.empty()) {
+ OS << "\n " << CallSites.size() << " Call Sites: ";
+ for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
+ if (i) OS << ", ";
+ WriteAsOperand(OS, CallSites[i].getCalledValue());
+ }
+ }
+ OS << "\n";
}
-void AliasSetTracker::add(CallInst *CI) {
- if (!AliasSets.empty()) {
- mergeAllSets();
- } else {
- AliasSets.push_back(AliasSet());
- }
- AliasSets[0].AccessTy = AliasSet::ModRef;
- AliasSets[0].AliasTy = AliasSet::MayAlias;
- AliasSets[0].Calls.push_back(CI);
+void AliasSetTracker::print(std::ostream &OS) const {
+ OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
+ << PointerMap.size() << " pointer values.\n";
+ for (const_iterator I = begin(), E = end(); I != E; ++I)
+ I->print(OS);
+ OS << "\n";
}
-void AliasSetTracker::add(InvokeInst *II) {
- if (!AliasSets.empty()) {
- mergeAllSets();
- } else {
- AliasSets.push_back(AliasSet());
- }
- AliasSets[0].AccessTy = AliasSet::ModRef;
- AliasSets[0].AliasTy = AliasSet::MayAlias;
- AliasSets[0].Invokes.push_back(II);
+void AliasSet::dump() const { print (std::cerr); }
+void AliasSetTracker::dump() const { print(std::cerr); }
+
+
+//===----------------------------------------------------------------------===//
+// AliasSetPrinter Pass
+//===----------------------------------------------------------------------===//
+
+namespace {
+ class AliasSetPrinter : public FunctionPass {
+ AliasSetTracker *Tracker;
+ public:
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+ AU.addRequired<AliasAnalysis>();
+ }
+
+ virtual bool runOnFunction(Function &F) {
+ Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
+
+ for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
+ Tracker->add(*I);
+ return false;
+ }
+
+ /// print - Convert to human readable form
+ virtual void print(std::ostream &OS) const {
+ Tracker->print(OS);
+ }
+
+ virtual void releaseMemory() {
+ delete Tracker;
+ }
+ };
+ RegisterPass<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer",
+ PassInfo::Analysis | PassInfo::Optimization);
}
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