Merge branch 'upstream' into merge-2012_09_10

Conflicts:
	lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
	lib/Support/DynamicLibrary.cpp
	lib/Support/LockFileManager.cpp

Change-Id: I91e94c3a7a76e19c688307c5a480a640a3bd2b7e

1 files changed, 118 insertions, 27 deletions

diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index 1d028c2..a3bc06a 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -85,9 +85,10 @@ static bool isEscapeSource(const Value *V) {
 /// getObjectSize - Return the size of the object specified by V, or
 /// UnknownSize if unknown.
 static uint64_t getObjectSize(const Value *V, const TargetData &TD,
+                              const TargetLibraryInfo &TLI,
                               bool RoundToAlign = false) {
   uint64_t Size;
-  if (getObjectSize(V, Size, &TD, RoundToAlign))
+  if (getObjectSize(V, Size, &TD, &TLI, RoundToAlign))
     return Size;
   return AliasAnalysis::UnknownSize;
 }
@@ -95,10 +96,11 @@ static uint64_t getObjectSize(const Value *V, const TargetData &TD,
 /// isObjectSmallerThan - Return true if we can prove that the object specified
 /// by V is smaller than Size.
 static bool isObjectSmallerThan(const Value *V, uint64_t Size,
-                                const TargetData &TD) {
+                                const TargetData &TD,
+                                const TargetLibraryInfo &TLI) {
   // This function needs to use the aligned object size because we allow
   // reads a bit past the end given sufficient alignment.
-  uint64_t ObjectSize = getObjectSize(V, TD, /*RoundToAlign*/true);
+  uint64_t ObjectSize = getObjectSize(V, TD, TLI, /*RoundToAlign*/true);
   
   return ObjectSize != AliasAnalysis::UnknownSize && ObjectSize < Size;
 }
@@ -106,8 +108,8 @@ static bool isObjectSmallerThan(const Value *V, uint64_t Size,
 /// isObjectSize - Return true if we can prove that the object specified
 /// by V has size Size.
 static bool isObjectSize(const Value *V, uint64_t Size,
-                         const TargetData &TD) {
-  uint64_t ObjectSize = getObjectSize(V, TD);
+                         const TargetData &TD, const TargetLibraryInfo &TLI) {
+  uint64_t ObjectSize = getObjectSize(V, TD, TLI);
   return ObjectSize != AliasAnalysis::UnknownSize && ObjectSize == Size;
 }
 
@@ -126,6 +128,15 @@ namespace {
     const Value *V;
     ExtensionKind Extension;
     int64_t Scale;
+
+    bool operator==(const VariableGEPIndex &Other) const {
+      return V == Other.V && Extension == Other.Extension &&
+        Scale == Other.Scale;
+    }
+
+    bool operator!=(const VariableGEPIndex &Other) const {
+      return !operator==(Other);
+    }
   };
 }
 
@@ -417,13 +428,7 @@ namespace {
   /// BasicAliasAnalysis - This is the primary alias analysis implementation.
   struct BasicAliasAnalysis : public ImmutablePass, public AliasAnalysis {
     static char ID; // Class identification, replacement for typeinfo
-    BasicAliasAnalysis() : ImmutablePass(ID),
-                           // AliasCache rarely has more than 1 or 2 elements,
-                           // so start it off fairly small so that clear()
-                           // doesn't have to tromp through 64 (the default)
-                           // elements on each alias query. This really wants
-                           // something like a SmallDenseMap.
-                           AliasCache(8) {
+    BasicAliasAnalysis() : ImmutablePass(ID) {
       initializeBasicAliasAnalysisPass(*PassRegistry::getPassRegistry());
     }
 
@@ -443,7 +448,11 @@ namespace {
              "BasicAliasAnalysis doesn't support interprocedural queries.");
       AliasResult Alias = aliasCheck(LocA.Ptr, LocA.Size, LocA.TBAATag,
                                      LocB.Ptr, LocB.Size, LocB.TBAATag);
-      AliasCache.clear();
+      // AliasCache rarely has more than 1 or 2 elements, always use
+      // shrink_and_clear so it quickly returns to the inline capacity of the
+      // SmallDenseMap if it ever grows larger.
+      // FIXME: This should really be shrink_to_inline_capacity_and_clear().
+      AliasCache.shrink_and_clear();
       return Alias;
     }
 
@@ -481,7 +490,7 @@ namespace {
   private:
     // AliasCache - Track alias queries to guard against recursion.
     typedef std::pair<Location, Location> LocPair;
-    typedef DenseMap<LocPair, AliasResult> AliasCacheTy;
+    typedef SmallDenseMap<LocPair, AliasResult, 8> AliasCacheTy;
     AliasCacheTy AliasCache;
 
     // Visited - Track instructions visited by pointsToConstantMemory.
@@ -490,6 +499,7 @@ namespace {
     // aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP
     // instruction against another.
     AliasResult aliasGEP(const GEPOperator *V1, uint64_t V1Size,
+                         const MDNode *V1TBAAInfo,
                          const Value *V2, uint64_t V2Size,
                          const MDNode *V2TBAAInfo,
                          const Value *UnderlyingV1, const Value *UnderlyingV2);
@@ -807,6 +817,21 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS,
   return ModRefResult(AliasAnalysis::getModRefInfo(CS, Loc) & Min);
 }
 
+static bool areVarIndicesEqual(SmallVector<VariableGEPIndex, 4> &Indices1,
+                               SmallVector<VariableGEPIndex, 4> &Indices2) {
+  unsigned Size1 = Indices1.size();
+  unsigned Size2 = Indices2.size();
+
+  if (Size1 != Size2)
+    return false;
+
+  for (unsigned I = 0; I != Size1; ++I)
+    if (Indices1[I] != Indices2[I])
+      return false;
+
+  return true;
+}
+
 /// aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP instruction
 /// against another pointer.  We know that V1 is a GEP, but we don't know
 /// anything about V2.  UnderlyingV1 is GetUnderlyingObject(GEP1, TD),
@@ -814,6 +839,7 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS,
 ///
 AliasAnalysis::AliasResult
 BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size,
+                             const MDNode *V1TBAAInfo,
                              const Value *V2, uint64_t V2Size,
                              const MDNode *V2TBAAInfo,
                              const Value *UnderlyingV1,
@@ -821,9 +847,41 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size,
   int64_t GEP1BaseOffset;
   SmallVector<VariableGEPIndex, 4> GEP1VariableIndices;
 
-  // If we have two gep instructions with must-alias'ing base pointers, figure
-  // out if the indexes to the GEP tell us anything about the derived pointer.
+  // If we have two gep instructions with must-alias or not-alias'ing base
+  // pointers, figure out if the indexes to the GEP tell us anything about the
+  // derived pointer.
   if (const GEPOperator *GEP2 = dyn_cast<GEPOperator>(V2)) {
+    // Check for geps of non-aliasing underlying pointers where the offsets are
+    // identical.
+    if (V1Size == V2Size) {
+      // Do the base pointers alias assuming type and size.
+      AliasResult PreciseBaseAlias = aliasCheck(UnderlyingV1, V1Size,
+                                                V1TBAAInfo, UnderlyingV2,
+                                                V2Size, V2TBAAInfo);
+      if (PreciseBaseAlias == NoAlias) {
+        // See if the computed offset from the common pointer tells us about the
+        // relation of the resulting pointer.
+        int64_t GEP2BaseOffset;
+        SmallVector<VariableGEPIndex, 4> GEP2VariableIndices;
+        const Value *GEP2BasePtr =
+          DecomposeGEPExpression(GEP2, GEP2BaseOffset, GEP2VariableIndices, TD);
+        const Value *GEP1BasePtr =
+          DecomposeGEPExpression(GEP1, GEP1BaseOffset, GEP1VariableIndices, TD);
+        // DecomposeGEPExpression and GetUnderlyingObject should return the
+        // same result except when DecomposeGEPExpression has no TargetData.
+        if (GEP1BasePtr != UnderlyingV1 || GEP2BasePtr != UnderlyingV2) {
+          assert(TD == 0 &&
+             "DecomposeGEPExpression and GetUnderlyingObject disagree!");
+          return MayAlias;
+        }
+        // Same offsets.
+        if (GEP1BaseOffset == GEP2BaseOffset &&
+            areVarIndicesEqual(GEP1VariableIndices, GEP2VariableIndices))
+          return NoAlias;
+        GEP1VariableIndices.clear();
+      }
+    }
+
     // Do the base pointers alias?
     AliasResult BaseAlias = aliasCheck(UnderlyingV1, UnknownSize, 0,
                                        UnderlyingV2, UnknownSize, 0);
@@ -843,9 +901,8 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size,
     const Value *GEP2BasePtr =
       DecomposeGEPExpression(GEP2, GEP2BaseOffset, GEP2VariableIndices, TD);
     
-    // If DecomposeGEPExpression isn't able to look all the way through the
-    // addressing operation, we must not have TD and this is too complex for us
-    // to handle without it.
+    // DecomposeGEPExpression and GetUnderlyingObject should return the
+    // same result except when DecomposeGEPExpression has no TargetData.
     if (GEP1BasePtr != UnderlyingV1 || GEP2BasePtr != UnderlyingV2) {
       assert(TD == 0 &&
              "DecomposeGEPExpression and GetUnderlyingObject disagree!");
@@ -879,9 +936,8 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size,
     const Value *GEP1BasePtr =
       DecomposeGEPExpression(GEP1, GEP1BaseOffset, GEP1VariableIndices, TD);
     
-    // If DecomposeGEPExpression isn't able to look all the way through the
-    // addressing operation, we must not have TD and this is too complex for us
-    // to handle without it.
+    // DecomposeGEPExpression and GetUnderlyingObject should return the
+    // same result except when DecomposeGEPExpression has no TargetData.
     if (GEP1BasePtr != UnderlyingV1) {
       assert(TD == 0 &&
              "DecomposeGEPExpression and GetUnderlyingObject disagree!");
@@ -1004,12 +1060,42 @@ BasicAliasAnalysis::aliasPHI(const PHINode *PN, uint64_t PNSize,
   // on corresponding edges.
   if (const PHINode *PN2 = dyn_cast<PHINode>(V2))
     if (PN2->getParent() == PN->getParent()) {
+      LocPair Locs(Location(PN, PNSize, PNTBAAInfo),
+                   Location(V2, V2Size, V2TBAAInfo));
+      if (PN > V2)
+        std::swap(Locs.first, Locs.second);
+
       AliasResult Alias =
         aliasCheck(PN->getIncomingValue(0), PNSize, PNTBAAInfo,
                    PN2->getIncomingValueForBlock(PN->getIncomingBlock(0)),
                    V2Size, V2TBAAInfo);
       if (Alias == MayAlias)
         return MayAlias;
+
+      // If the first source of the PHI nodes NoAlias and the other inputs are
+      // the PHI node itself through some amount of recursion this does not add
+      // any new information so just return NoAlias.
+      // bb:
+      //    ptr = ptr2 + 1
+      // loop:
+      //    ptr_phi = phi [bb, ptr], [loop, ptr_plus_one]
+      //    ptr2_phi = phi [bb, ptr2], [loop, ptr2_plus_one]
+      //    ...
+      //    ptr_plus_one = gep ptr_phi, 1
+      //    ptr2_plus_one = gep ptr2_phi, 1
+      // We assume for the recursion that the the phis (ptr_phi, ptr2_phi) do
+      // not alias each other.
+      bool ArePhisAssumedNoAlias = false;
+      AliasResult OrigAliasResult;
+      if (Alias == NoAlias) {
+        // Pretend the phis do not alias.
+        assert(AliasCache.count(Locs) &&
+               "There must exist an entry for the phi node");
+        OrigAliasResult = AliasCache[Locs];
+        AliasCache[Locs] = NoAlias;
+        ArePhisAssumedNoAlias = true;
+      }
+
       for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) {
         AliasResult ThisAlias =
           aliasCheck(PN->getIncomingValue(i), PNSize, PNTBAAInfo,
@@ -1019,6 +1105,11 @@ BasicAliasAnalysis::aliasPHI(const PHINode *PN, uint64_t PNSize,
         if (Alias == MayAlias)
           break;
       }
+
+      // Reset if speculation failed.
+      if (ArePhisAssumedNoAlias && Alias != NoAlias)
+        AliasCache[Locs] = OrigAliasResult;
+
       return Alias;
     }
 
@@ -1133,8 +1224,8 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size,
   // If the size of one access is larger than the entire object on the other
   // side, then we know such behavior is undefined and can assume no alias.
   if (TD)
-    if ((V1Size != UnknownSize && isObjectSmallerThan(O2, V1Size, *TD)) ||
-        (V2Size != UnknownSize && isObjectSmallerThan(O1, V2Size, *TD)))
+    if ((V1Size != UnknownSize && isObjectSmallerThan(O2, V1Size, *TD, *TLI)) ||
+        (V2Size != UnknownSize && isObjectSmallerThan(O1, V2Size, *TD, *TLI)))
       return NoAlias;
   
   // Check the cache before climbing up use-def chains. This also terminates
@@ -1156,7 +1247,7 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size,
     std::swap(O1, O2);
   }
   if (const GEPOperator *GV1 = dyn_cast<GEPOperator>(V1)) {
-    AliasResult Result = aliasGEP(GV1, V1Size, V2, V2Size, V2TBAAInfo, O1, O2);
+    AliasResult Result = aliasGEP(GV1, V1Size, V1TBAAInfo, V2, V2Size, V2TBAAInfo, O1, O2);
     if (Result != MayAlias) return AliasCache[Locs] = Result;
   }
 
@@ -1184,8 +1275,8 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size,
   // accesses is accessing the entire object, then the accesses must
   // overlap in some way.
   if (TD && O1 == O2)
-    if ((V1Size != UnknownSize && isObjectSize(O1, V1Size, *TD)) ||
-        (V2Size != UnknownSize && isObjectSize(O2, V2Size, *TD)))
+    if ((V1Size != UnknownSize && isObjectSize(O1, V1Size, *TD, *TLI)) ||
+        (V2Size != UnknownSize && isObjectSize(O2, V2Size, *TD, *TLI)))
       return AliasCache[Locs] = PartialAlias;
 
   AliasResult Result =