[AliasSetTracker] Use mod/ref information for UnknownInstr

AliasSetTracker does not need to convert the access mode to ModRefAccess if the
new visited UnknownInst has only 'REF' modrefinfo to existing pointers in the
sets.

Patch by Andrew Zhogin!

llvm-svn: 251451

1 files changed, 75 insertions, 39 deletions

diff --git a/llvm/lib/Analysis/AliasSetTracker.cpp b/llvm/lib/Analysis/AliasSetTracker.cpp
index 3094049b3cc..a1f57089492 100644
--- a/llvm/lib/Analysis/AliasSetTracker.cpp
+++ b/llvm/lib/Analysis/AliasSetTracker.cpp
@@ -95,7 +95,7 @@ void AliasSet::removeFromTracker(AliasSetTracker &AST) {
 
 void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
                           uint64_t Size, const AAMDNodes &AAInfo,
-                          bool KnownMustAlias) {
+                          ModRefInfo MR, bool KnownMustAlias) {
   assert(!Entry.hasAliasSet() && "Entry already in set!");
 
   // Check to see if we have to downgrade to _may_ alias.
@@ -112,6 +112,9 @@ void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
       assert(Result != NoAlias && "Cannot be part of must set!");
     }
 
+  // upgrading access if existing UnknownInst has ModRef with new pointer
+  Access |= MR;
+
   Entry.setAliasSet(this);
   Entry.updateSizeAndAAInfo(Size, AAInfo);
 
@@ -123,20 +126,34 @@ void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
   addRef();               // Entry points to alias set.
 }
 
-void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
+void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA,
+                              ModRefInfo MR) {
   if (UnknownInsts.empty())
     addRef();
   UnknownInsts.emplace_back(I);
 
   if (!I->mayWriteToMemory()) {
     Alias = SetMayAlias;
-    Access |= RefAccess;
+    Access |= MRI_Ref;
     return;
   }
 
-  // FIXME: This should use mod/ref information to make this not suck so bad
   Alias = SetMayAlias;
-  Access = ModRefAccess;
+  Access |= MR;
+}
+
+namespace {
+  /// returns true if there is no request of worst ModRefInfo
+  ///   (MRcommonPtr is null)
+  /// or when achieved maximum ModRefInfo (MRI_ModRef).
+  bool processMR(ModRefInfo MR, ModRefInfo* MRcommonPtr, ModRefInfo& MRcommon) {
+    MRcommon = ModRefInfo(MRcommon | MR);
+    return !MRcommonPtr || (MRcommon == MRI_ModRef);
+  }
+  bool fillExitMR(ModRefInfo* MRcommonPtr, ModRefInfo& MRcommon) {
+    if (MRcommonPtr) *MRcommonPtr = MRcommon;
+    return MRcommon != MRI_NoModRef;
+  }
 }
 
 /// aliasesPointer - Return true if the specified pointer "may" (or must)
@@ -144,7 +161,8 @@ void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
 ///
 bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
                               const AAMDNodes &AAInfo,
-                              AliasAnalysis &AA) const {
+                              AliasAnalysis &AA,
+                              ModRefInfo* MRcommonPtr) const {
   if (Alias == SetMustAlias) {
     assert(UnknownInsts.empty() && "Illegal must alias set!");
 
@@ -164,35 +182,44 @@ bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
                  MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo())))
       return true;
 
+  // to gather worst ModRefInfo
+  ModRefInfo MRcommon = MRI_NoModRef;
+
   // Check the unknown instructions...
   if (!UnknownInsts.empty()) {
     for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i)
-      if (AA.getModRefInfo(UnknownInsts[i],
-                           MemoryLocation(Ptr, Size, AAInfo)) != MRI_NoModRef)
-        return true;
+      if (processMR(AA.getModRefInfo(UnknownInsts[i],
+          MemoryLocation(Ptr, Size, AAInfo)), MRcommonPtr, MRcommon))
+        return fillExitMR(MRcommonPtr, MRcommon);
   }
 
-  return false;
+  return fillExitMR(MRcommonPtr, MRcommon);
 }
 
 bool AliasSet::aliasesUnknownInst(const Instruction *Inst,
-                                  AliasAnalysis &AA) const {
+                                  AliasAnalysis &AA,
+                                  ModRefInfo* MRcommonPtr) const {
   if (!Inst->mayReadOrWriteMemory())
     return false;
 
+  // to gather worst ModRefInfo
+  ModRefInfo MRcommon = MRI_NoModRef;
+
   for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
     ImmutableCallSite C1(getUnknownInst(i)), C2(Inst);
-    if (!C1 || !C2 || AA.getModRefInfo(C1, C2) != MRI_NoModRef ||
-        AA.getModRefInfo(C2, C1) != MRI_NoModRef)
-      return true;
+    if (!C1 || !C2 ||
+      processMR(AA.getModRefInfo(C1, C2), MRcommonPtr, MRcommon) ||
+      processMR(AA.getModRefInfo(C2, C1), MRcommonPtr, MRcommon))
+      return fillExitMR(MRcommonPtr, MRcommon);
   }
 
-  for (iterator I = begin(), E = end(); I != E; ++I)
-    if (AA.getModRefInfo(Inst, MemoryLocation(I.getPointer(), I.getSize(),
-                                              I.getAAInfo())) != MRI_NoModRef)
-      return true;
-
-  return false;
+  for (iterator I = begin(), E = end(); I != E; ++I) {
+    ModRefInfo MR = AA.getModRefInfo(
+      Inst, MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo()));
+    if (processMR(MR, MRcommonPtr, MRcommon))
+      return fillExitMR(MRcommonPtr, MRcommon);
+  }
+  return fillExitMR(MRcommonPtr, MRcommon);
 }
 
 void AliasSetTracker::clear() {
@@ -214,11 +241,15 @@ void AliasSetTracker::clear() {
 ///
 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
                                                   uint64_t Size,
-                                                  const AAMDNodes &AAInfo) {
+                                                  const AAMDNodes &AAInfo,
+                                                  ModRefInfo* MRcommonPtr) {
   AliasSet *FoundSet = nullptr;
   for (iterator I = begin(), E = end(); I != E;) {
     iterator Cur = I++;
-    if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, AAInfo, AA)) continue;
+    ModRefInfo MR = MRI_NoModRef;
+    if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, AAInfo, AA, &MR))
+      continue;
+    *MRcommonPtr = ModRefInfo(*MRcommonPtr | MR);
     
     if (!FoundSet) {      // If this is the first alias set ptr can go into.
       FoundSet = &*Cur;   // Remember it.
@@ -248,12 +279,15 @@ bool AliasSetTracker::containsUnknown(const Instruction *Inst) const {
   return false;
 }
 
-AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
+AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst,
+                                                      ModRefInfo* MRcommonPtr) {
   AliasSet *FoundSet = nullptr;
   for (iterator I = begin(), E = end(); I != E;) {
     iterator Cur = I++;
-    if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA))
+    ModRefInfo MR = MRI_NoModRef;
+    if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA, &MR))
       continue;
+    *MRcommonPtr = ModRefInfo(*MRcommonPtr | MR);
     if (!FoundSet)            // If this is the first alias set ptr can go into.
       FoundSet = &*Cur;       // Remember it.
     else if (!Cur->Forward)   // Otherwise, we must merge the sets.
@@ -279,22 +313,23 @@ AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, uint64_t Size,
     return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
   }
   
-  if (AliasSet *AS = findAliasSetForPointer(Pointer, Size, AAInfo)) {
+  ModRefInfo MR = MRI_NoModRef;
+  if (AliasSet *AS = findAliasSetForPointer(Pointer, Size, AAInfo, &MR)) {
     // Add it to the alias set it aliases.
-    AS->addPointer(*this, Entry, Size, AAInfo);
+    AS->addPointer(*this, Entry, Size, AAInfo, MR);
     return *AS;
   }
   
   if (New) *New = true;
   // Otherwise create a new alias set to hold the loaded pointer.
   AliasSets.push_back(new AliasSet());
-  AliasSets.back().addPointer(*this, Entry, Size, AAInfo);
+  AliasSets.back().addPointer(*this, Entry, Size, AAInfo, MRI_NoModRef);
   return AliasSets.back();
 }
 
 bool AliasSetTracker::add(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
   bool NewPtr;
-  addPointer(Ptr, Size, AAInfo, AliasSet::NoAccess, NewPtr);
+  addPointer(Ptr, Size, AAInfo, MRI_NoModRef, NewPtr);
   return NewPtr;
 }
 
@@ -305,7 +340,7 @@ bool AliasSetTracker::add(LoadInst *LI) {
   AAMDNodes AAInfo;
   LI->getAAMetadata(AAInfo);
 
-  AliasSet::AccessLattice Access = AliasSet::RefAccess;
+  AliasSet::AccessLattice Access = MRI_Ref;
   bool NewPtr;
   const DataLayout &DL = LI->getModule()->getDataLayout();
   AliasSet &AS = addPointer(LI->getOperand(0),
@@ -321,7 +356,7 @@ bool AliasSetTracker::add(StoreInst *SI) {
   AAMDNodes AAInfo;
   SI->getAAMetadata(AAInfo);
 
-  AliasSet::AccessLattice Access = AliasSet::ModAccess;
+  AliasSet::AccessLattice Access = MRI_Mod;
   bool NewPtr;
   const DataLayout &DL = SI->getModule()->getDataLayout();
   Value *Val = SI->getOperand(0);
@@ -338,7 +373,7 @@ bool AliasSetTracker::add(VAArgInst *VAAI) {
 
   bool NewPtr;
   addPointer(VAAI->getOperand(0), MemoryLocation::UnknownSize, AAInfo,
-             AliasSet::ModRefAccess, NewPtr);
+             MRI_ModRef, NewPtr);
   return NewPtr;
 }
 
@@ -349,14 +384,15 @@ bool AliasSetTracker::addUnknown(Instruction *Inst) {
   if (!Inst->mayReadOrWriteMemory())
     return true; // doesn't alias anything
 
-  AliasSet *AS = findAliasSetForUnknownInst(Inst);
+  ModRefInfo MR = MRI_NoModRef;
+  AliasSet *AS = findAliasSetForUnknownInst(Inst, &MR);
   if (AS) {
-    AS->addUnknownInst(Inst, AA);
+    AS->addUnknownInst(Inst, AA, MR);
     return false;
   }
   AliasSets.push_back(new AliasSet());
   AS = &AliasSets.back();
-  AS->addUnknownInst(Inst, AA);
+  AS->addUnknownInst(Inst, AA, MR);
   return true;
 }
 
@@ -556,7 +592,7 @@ void AliasSetTracker::copyValue(Value *From, Value *To) {
   I = PointerMap.find_as(From);
   AliasSet *AS = I->second->getAliasSet(*this);
   AS->addPointer(*this, Entry, I->second->getSize(),
-                 I->second->getAAInfo(),
+                 I->second->getAAInfo(), MRI_NoModRef,
                  true);
 }
 
@@ -570,10 +606,10 @@ void AliasSet::print(raw_ostream &OS) const {
   OS << "  AliasSet[" << (const void*)this << ", " << RefCount << "] ";
   OS << (Alias == SetMustAlias ? "must" : "may") << " alias, ";
   switch (Access) {
-  case NoAccess:     OS << "No access "; break;
-  case RefAccess:    OS << "Ref       "; break;
-  case ModAccess:    OS << "Mod       "; break;
-  case ModRefAccess: OS << "Mod/Ref   "; break;
+  case MRI_NoModRef:     OS << "No access "; break;
+  case MRI_Ref:          OS << "Ref       "; break;
+  case MRI_Mod:          OS << "Mod       "; break;
+  case MRI_ModRef:       OS << "Mod/Ref   "; break;
   default: llvm_unreachable("Bad value for Access!");
   }
   if (isVolatile()) OS << "[volatile] ";