Do not delete the entry block to a function.

[oota-llvm.git] / lib / Analysis / AliasSetTracker.cpp

diff --git a/lib/Analysis/AliasSetTracker.cpp b/lib/Analysis/AliasSetTracker.cpp
index 2da144c35fe809b52b91a31cc5178e4f2fc75849..85937adb3896bf3222a03b9e918a68fcb598cf41 100644 (file)
--- a/lib/Analysis/AliasSetTracker.cpp
+++ b/lib/Analysis/AliasSetTracker.cpp
@@ -21,9 +21,9 @@
 #include <iostream>
 using namespace llvm;
 
-/// mergeSetIn - Merge the specified alias set into this alias set...
+/// mergeSetIn - Merge the specified alias set into this alias set.
 ///
-void AliasSet::mergeSetIn(AliasSet &AS) {
+void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
   assert(!AS.Forward && "Alias set is already forwarding!");
   assert(!Forward && "This set is a forwarding set!!");
 
@@ -31,6 +31,20 @@ void AliasSet::mergeSetIn(AliasSet &AS) {
   AccessTy |= AS.AccessTy;
   AliasTy  |= AS.AliasTy;
 
+  if (AliasTy == MustAlias) {
+    // Check that these two merged sets really are must aliases.  Since both
+    // used to be must-alias sets, we can just check any pointer from each set
+    // for aliasing.
+    AliasAnalysis &AA = AST.getAliasAnalysis();
+    HashNodePair *L = getSomePointer();
+    HashNodePair *R = AS.getSomePointer();
+
+    // If the pointers are not a must-alias pair, this set becomes a may alias.
+    if (AA.alias(L->first, L->second.getSize(), R->first, R->second.getSize())
+        != AliasAnalysis::MustAlias)
+      AliasTy = MayAlias;
+  }
+
   if (CallSites.empty()) {            // Merge call sites...
     if (!AS.CallSites.empty())
       std::swap(CallSites, AS.CallSites);
@@ -179,24 +193,36 @@ AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
   AliasSet *FoundSet = 0;
   for (iterator I = begin(), E = end(); I != E; ++I)
     if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) {
-      if (FoundSet == 0) {  // If this is the first alias set ptr can go into...
+      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...
+      } else {              // Otherwise, we must merge the sets.
+        FoundSet->mergeSetIn(*I, *this);     // Merge in contents.
       }
     }
 
   return FoundSet;
 }
 
+/// containsPointer - Return true if the specified location is represented by
+/// this alias set, false otherwise.  This does not modify the AST object or
+/// alias sets.
+bool AliasSetTracker::containsPointer(Value *Ptr, unsigned Size) const {
+  for (const_iterator I = begin(), E = end(); I != E; ++I)
+    if (!I->Forward && I->aliasesPointer(Ptr, Size, AA))
+      return true;
+  return false;
+}
+
+
+
 AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
   AliasSet *FoundSet = 0;
   for (iterator I = begin(), E = end(); I != E; ++I)
     if (!I->Forward && I->aliasesCallSite(CS, AA)) {
-      if (FoundSet == 0) {  // If this is the first alias set ptr can go into...
+      if (FoundSet == 0) {  // If this is the first alias set ptr can go into.
         FoundSet = I;       // Remember it.
-      } else if (!I->Forward) {     // Otherwise, we must merge the sets...
-        FoundSet->mergeSetIn(*I);     // Merge in contents...
+      } else if (!I->Forward) {     // Otherwise, we must merge the sets.
+        FoundSet->mergeSetIn(*I, *this);     // Merge in contents.
       }
     }
 
@@ -513,7 +539,7 @@ namespace {
     }
 
     /// print - Convert to human readable form
-    virtual void print(std::ostream &OS) const {
+    virtual void print(std::ostream &OS, const Module* = 0) const {
       Tracker->print(OS);
     }