[AliasSetTracker] Misc cleanup (NFCI)

Summary: Remove two redundant checks, add one in the unit test. Remove an unused method. Fix computation of TotalMayAliasSetSize.
llvm-svn: 345911

1 files changed, 6 insertions, 14 deletions

diff --git a/llvm/lib/Analysis/AliasSetTracker.cpp b/llvm/lib/Analysis/AliasSetTracker.cpp
index 22c8ae20113..c152b0ddeca 100644
--- a/llvm/lib/Analysis/AliasSetTracker.cpp
+++ b/llvm/lib/Analysis/AliasSetTracker.cpp
@@ -114,10 +114,9 @@ void AliasSetTracker::removeAliasSet(AliasSet *AS) {
   if (AliasSet *Fwd = AS->Forward) {
     Fwd->dropRef(*this);
     AS->Forward = nullptr;
-  }
-
-  if (AS->Alias == AliasSet::SetMayAlias)
-    TotalMayAliasSetSize -= AS->size();
+  } else // Update TotalMayAliasSetSize only if not forwarding.
+      if (AS->Alias == AliasSet::SetMayAlias)
+        TotalMayAliasSetSize -= AS->size();
 
   AliasSets.erase(AS);
 }
@@ -232,8 +231,8 @@ bool AliasSet::aliasesUnknownInst(const Instruction *Inst,
   if (AliasAny)
     return true;
 
-  if (!Inst->mayReadOrWriteMemory())
-    return false;
+  assert(Inst->mayReadOrWriteMemory() &&
+         "Instruction must either read or write memory.");
 
   for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
     if (auto *UnknownInst = getUnknownInst(i)) {
@@ -311,13 +310,6 @@ AliasSet *AliasSetTracker::mergeAliasSetsForPointer(const Value *Ptr,
   return FoundSet;
 }
 
-bool AliasSetTracker::containsUnknown(const Instruction *Inst) const {
-  for (const AliasSet &AS : *this)
-    if (!AS.Forward && AS.aliasesUnknownInst(Inst, AA))
-      return true;
-  return false;
-}
-
 AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
   AliasSet *FoundSet = nullptr;
   for (iterator I = begin(), E = end(); I != E;) {
@@ -326,7 +318,7 @@ AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
       continue;
     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.
+    else   // Otherwise, we must merge the sets.
       FoundSet->mergeSetIn(*Cur, *this);     // Merge in contents.
   }
   return FoundSet;