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https://github.com/c64scene-ar/llvm-6502.git
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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. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5619 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
+219
-112
@@ -9,164 +9,271 @@
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#include "llvm/iMemory.h"
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#include "llvm/iOther.h"
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#include "llvm/iTerminators.h"
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/// updateAccessTypes - Depending on what type of accesses are in this set,
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/// decide whether the set contains just references, just modifications, or a
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/// mix.
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///
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void AliasSet::updateAccessType() {
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if (!Calls.empty() || !Invokes.empty()) {
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AccessTy = ModRef;
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} else if (!Loads.empty()) {
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if (Stores.empty())
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AccessTy = Refs;
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else
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AccessTy = ModRef;
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} else {
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AccessTy = Mods;
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}
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}
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#include "llvm/Pass.h"
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#include "llvm/Assembly/Writer.h"
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#include "llvm/Support/InstIterator.h"
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/// mergeSetIn - Merge the specified alias set into this alias set...
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///
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void AliasSet::mergeSetIn(const AliasSet &AS) {
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// Merge instruction sets...
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Loads.insert( Loads.end(), AS.Loads.begin() , AS.Loads.end());
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Stores.insert( Stores.end(), AS.Stores.begin() , AS.Stores.end());
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Calls.insert( Calls.end(), AS.Calls.begin() , AS.Calls.end());
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Invokes.insert(Invokes.end(), AS.Invokes.begin(), AS.Invokes.end());
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void AliasSet::mergeSetIn(AliasSet &AS) {
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assert(!AS.Forward && "Alias set is already forwarding!");
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assert(!Forward && "This set is a forwarding set!!");
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// Update the alias and access types of this set...
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if (AS.getAliasType() == MayAlias)
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AliasTy = MayAlias;
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updateAccessType();
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AccessTy |= AS.AccessTy;
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AliasTy |= AS.AliasTy;
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if (CallSites.empty()) { // Merge call sites...
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if (!AS.CallSites.empty())
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std::swap(CallSites, AS.CallSites);
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} else if (!AS.CallSites.empty()) {
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CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end());
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AS.CallSites.clear();
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}
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// FIXME: If AS's refcount is zero, nuke it now...
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assert(RefCount != 0);
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AS.Forward = this; // Forward across AS now...
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RefCount++; // AS is now pointing to us...
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// Merge the list of constituent pointers...
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PtrListTail->second.setTail(AS.PtrListHead);
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PtrListTail = AS.PtrListTail;
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AS.PtrListHead = AS.PtrListTail = 0;
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}
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/// pointerAliasesSet - Return true if the specified pointer "may" (or must)
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void AliasSetTracker::removeAliasSet(AliasSet *AS) {
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AliasSets.erase(AS);
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}
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void AliasSet::removeFromTracker(AliasSetTracker &AST) {
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assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
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AST.removeAliasSet(this);
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}
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void AliasSet::addPointer(AliasSetTracker &AST, HashNodePair &Entry){
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assert(!Entry.second.hasAliasSet() && "Entry already in set!");
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AliasAnalysis &AA = AST.getAliasAnalysis();
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if (isMustAlias()) // Check to see if we have to downgrade to _may_ alias
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if (Value *V = getSomePointer())
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if (AA.alias(V, Entry.first) == AliasAnalysis::MayAlias)
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AliasTy = MayAlias;
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Entry.second.setAliasSet(this);
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// Add it to the end of the list...
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if (PtrListTail)
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PtrListTail->second.setTail(&Entry);
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else
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PtrListHead = &Entry;
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PtrListTail = &Entry;
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RefCount++; // Entry points to alias set...
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}
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void AliasSet::addCallSite(CallSite CS) {
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CallSites.push_back(CS);
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AliasTy = MayAlias; // FIXME: Too conservative
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}
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/// aliasesPointer - Return true if the specified pointer "may" (or must)
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/// alias one of the members in the set.
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///
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bool AliasSet::pointerAliasesSet(const Value *Ptr, AliasAnalysis &AA) const {
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if (!Calls.empty() || !Invokes.empty())
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bool AliasSet::aliasesPointer(const Value *Ptr, AliasAnalysis &AA) const {
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if (AliasTy == MustAlias) {
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assert(CallSites.empty() && "Illegal must alias set!");
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// If this is a set of MustAliases, only check to see if the pointer aliases
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// SOME value in the set...
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Value *SomePtr = getSomePointer();
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assert(SomePtr && "Empty must-alias set??");
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return AA.alias(SomePtr, Ptr);
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}
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// If this is a may-alias set, we have to check all of the pointers in the set
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// to be sure it doesn't alias the set...
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for (iterator I = begin(), E = end(); I != E; ++I)
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if (AA.alias(Ptr, *I))
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return true;
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// Check the call sites list and invoke list...
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if (!CallSites.empty())
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// FIXME: this is pessimistic!
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return true;
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for (unsigned i = 0, e = Loads.size(); i != e; ++i)
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if (AA.alias(Ptr, Loads[i]->getOperand(0)))
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return true;
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for (unsigned i = 0, e = Stores.size(); i != e; ++i)
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if (AA.alias(Ptr, Stores[i]->getOperand(1)))
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return true;
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return false;
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}
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/// getSomePointer - This method may only be called when the AliasType of the
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/// set is MustAlias. This is used to return any old pointer (which must alias
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/// all other pointers in the set) so that the caller can decide whether to turn
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/// this set into a may alias set or not.
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///
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Value *AliasSet::getSomePointer() const {
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assert(getAliasType() == MustAlias &&
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"Cannot call getSomePointer on a 'MayAlias' set!");
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assert(Calls.empty() && Invokes.empty() && "Call/invokes mean may alias!");
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if (!Loads.empty())
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return Loads[0]->getOperand(0);
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assert(!Stores.empty() && "There are no instructions in this set!");
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return Stores[0]->getOperand(1);
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bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
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// FIXME: Too conservative!
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return true;
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}
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/// findAliasSetForPointer - Given a pointer, find the one alias set to put the
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/// instruction referring to the pointer into. If there are multiple alias sets
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/// that may alias the pointer, merge them together and return the unified set.
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///
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AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr) {
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AliasSet *FoundSet = 0;
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for (unsigned i = 0; i != AliasSets.size(); ++i) {
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if (AliasSets[i].pointerAliasesSet(Ptr, AA)) {
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for (iterator I = begin(), E = end(); I != E; ++I)
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if (I->aliasesPointer(Ptr, AA)) {
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if (FoundSet == 0) { // If this is the first alias set ptr can go into...
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FoundSet = &AliasSets[i]; // Remember it.
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FoundSet = I; // Remember it.
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} else { // Otherwise, we must merge the sets...
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FoundSet->mergeSetIn(AliasSets[i]); // Merge in contents...
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AliasSets.erase(AliasSets.begin()+i); // Remove the set...
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--i; // Don't skip the next set
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FoundSet->mergeSetIn(*I); // Merge in contents...
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}
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}
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return FoundSet;
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}
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AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
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AliasSet *FoundSet = 0;
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for (iterator I = begin(), E = end(); I != E; ++I)
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if (I->aliasesCallSite(CS, AA)) {
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if (FoundSet == 0) { // If this is the first alias set ptr can go into...
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FoundSet = I; // Remember it.
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} else { // Otherwise, we must merge the sets...
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FoundSet->mergeSetIn(*I); // Merge in contents...
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}
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}
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}
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return FoundSet;
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}
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void AliasSetTracker::add(LoadInst *LI) {
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Value *Pointer = LI->getOperand(0);
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// Check to see if the loaded pointer aliases any sets...
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AliasSet *AS = findAliasSetForPointer(Pointer);
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if (AS) {
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AS->Loads.push_back(LI);
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// Check to see if we need to change this into a MayAlias set now...
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if (AS->getAliasType() == AliasSet::MustAlias)
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if (AA.alias(AS->getSomePointer(), Pointer) != AliasAnalysis::MustAlias)
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AS->AliasTy = AliasSet::MayAlias;
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AS->updateAccessType();
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/// getAliasSetForPointer - Return the alias set that the specified pointer
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/// lives in...
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AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer) {
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AliasSet::HashNodePair &Entry = getEntryFor(Pointer);
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// Check to see if the pointer is already known...
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if (Entry.second.hasAliasSet()) {
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// Return the set!
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return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this);
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} else if (AliasSet *AS = findAliasSetForPointer(Pointer)) {
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// Add it to the alias set it aliases...
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AS->addPointer(*this, Entry);
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return *AS;
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} else {
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// Otherwise create a new alias set to hold the load...
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// Otherwise create a new alias set to hold the loaded pointer...
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AliasSets.push_back(AliasSet());
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AliasSets.back().Loads.push_back(LI);
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AliasSets.back().AccessTy = AliasSet::Refs;
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AliasSets.back().addPointer(*this, Entry);
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return AliasSets.back();
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}
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}
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void AliasSetTracker::add(LoadInst *LI) {
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addPointer(LI->getOperand(0), AliasSet::Refs);
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}
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void AliasSetTracker::add(StoreInst *SI) {
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Value *Pointer = SI->getOperand(1);
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addPointer(SI->getOperand(1), AliasSet::Mods);
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}
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// Check to see if the loaded pointer aliases any sets...
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AliasSet *AS = findAliasSetForPointer(Pointer);
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if (AS) {
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AS->Stores.push_back(SI);
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// Check to see if we need to change this into a MayAlias set now...
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if (AS->getAliasType() == AliasSet::MustAlias)
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if (AA.alias(AS->getSomePointer(), Pointer) != AliasAnalysis::MustAlias)
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AS->AliasTy = AliasSet::MayAlias;
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AS->updateAccessType();
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} else {
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// Otherwise create a new alias set to hold the load...
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void AliasSetTracker::add(CallSite CS) {
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AliasSet *AS = findAliasSetForCallSite(CS);
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if (!AS) {
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AliasSets.push_back(AliasSet());
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AliasSets.back().Stores.push_back(SI);
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AliasSets.back().AccessTy = AliasSet::Mods;
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AS = &AliasSets.back();
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}
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AS->addCallSite(CS);
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}
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void AliasSetTracker::mergeAllSets() {
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if (AliasSets.size() < 2) return; // Noop
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// Merge all of the sets into set #0
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for (unsigned i = 1, e = AliasSets.size(); i != e; ++i)
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AliasSets[0].mergeSetIn(AliasSets[i]);
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// Delete extraneous sets...
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AliasSets.erase(AliasSets.begin()+1, AliasSets.end());
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void AliasSetTracker::add(Instruction *I) {
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// Dispatch to one of the other add methods...
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if (LoadInst *LI = dyn_cast<LoadInst>(I))
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add(LI);
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else if (StoreInst *SI = dyn_cast<StoreInst>(I))
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add(SI);
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else if (CallInst *CI = dyn_cast<CallInst>(I))
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add(CI);
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else if (InvokeInst *II = dyn_cast<InvokeInst>(I))
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add(II);
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}
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void AliasSetTracker::add(CallInst *CI) {
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if (!AliasSets.empty()) {
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mergeAllSets();
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} else {
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AliasSets.push_back(AliasSet());
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//===----------------------------------------------------------------------===//
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// AliasSet/AliasSetTracker Printing Support
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//===----------------------------------------------------------------------===//
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void AliasSet::print(std::ostream &OS) const {
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OS << " AliasSet[" << (void*)this << "," << RefCount << "] ";
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OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, ";
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switch (AccessTy) {
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case NoModRef: OS << "No access "; break;
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case Refs : OS << "Ref "; break;
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case Mods : OS << "Mod "; break;
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case ModRef : OS << "Mod/Ref "; break;
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default: assert(0 && "Bad value for AccessTy!");
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}
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AliasSets[0].AccessTy = AliasSet::ModRef;
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AliasSets[0].AliasTy = AliasSet::MayAlias;
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AliasSets[0].Calls.push_back(CI);
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if (Forward)
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OS << " forwarding to " << (void*)Forward;
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if (begin() != end()) {
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OS << "Pointers: ";
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for (iterator I = begin(), E = end(); I != E; ++I) {
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if (I != begin()) OS << ", ";
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WriteAsOperand(OS, *I);
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}
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}
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if (!CallSites.empty()) {
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OS << "\n " << CallSites.size() << " Call Sites: ";
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for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
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if (i) OS << ", ";
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WriteAsOperand(OS, CallSites[i].getCalledValue());
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}
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}
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OS << "\n";
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}
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void AliasSetTracker::add(InvokeInst *II) {
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if (!AliasSets.empty()) {
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mergeAllSets();
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} else {
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AliasSets.push_back(AliasSet());
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}
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AliasSets[0].AccessTy = AliasSet::ModRef;
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AliasSets[0].AliasTy = AliasSet::MayAlias;
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AliasSets[0].Invokes.push_back(II);
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void AliasSetTracker::print(std::ostream &OS) const {
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OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
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<< PointerMap.size() << " pointer values.\n";
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for (const_iterator I = begin(), E = end(); I != E; ++I)
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I->print(OS);
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OS << "\n";
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}
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void AliasSet::dump() const { print (std::cerr); }
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void AliasSetTracker::dump() const { print(std::cerr); }
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//===----------------------------------------------------------------------===//
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// AliasSetPrinter Pass
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//===----------------------------------------------------------------------===//
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namespace {
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class AliasSetPrinter : public FunctionPass {
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AliasSetTracker *Tracker;
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public:
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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AU.addRequired<AliasAnalysis>();
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}
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virtual bool runOnFunction(Function &F) {
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Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
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for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
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Tracker->add(*I);
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return false;
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}
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/// print - Convert to human readable form
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virtual void print(std::ostream &OS) const {
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Tracker->print(OS);
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}
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virtual void releaseMemory() {
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delete Tracker;
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}
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};
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RegisterPass<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer",
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PassInfo::Analysis | PassInfo::Optimization);
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}
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