X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FTypeBasedAliasAnalysis.cpp;h=0faf1398ec76609775e1a05d91252f0e964d5d4b;hb=6c3541d5597033bdb2f26f5ade811b482c32a39a;hp=f2fe35db33f0ffacd8257b8a19be00da98c56450;hpb=ae92af6771f0a87b380706bc20e69d90bc0c1818;p=oota-llvm.git

diff --git a/lib/Analysis/TypeBasedAliasAnalysis.cpp b/lib/Analysis/TypeBasedAliasAnalysis.cpp
index f2fe35db33f..0faf1398ec7 100644
--- a/lib/Analysis/TypeBasedAliasAnalysis.cpp
+++ b/lib/Analysis/TypeBasedAliasAnalysis.cpp
@@ -31,7 +31,7 @@
 //
 // The second field identifies the type's parent node in the tree, or
 // is null or omitted for a root node. A type is considered to alias
-// all of its decendents and all of its ancestors in the tree. Also,
+// all of its descendants and all of its ancestors in the tree. Also,
 // a type is considered to alias all types in other trees, so that
 // bitcode produced from multiple front-ends is handled conservatively.
 //
@@ -59,14 +59,18 @@
 
 #include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/Analysis/Passes.h"
+#include "llvm/Constants.h"
+#include "llvm/LLVMContext.h"
 #include "llvm/Module.h"
 #include "llvm/Metadata.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/CommandLine.h"
 using namespace llvm;
 
-// For testing purposes, enable TBAA only via a special option.
-static cl::opt<bool> EnableTBAA("enable-tbaa");
+// A handy option for disabling TBAA functionality. The same effect can also be
+// achieved by stripping the !tbaa tags from IR, but this option is sometimes
+// more convenient.
+static cl::opt<bool> EnableTBAA("enable-tbaa", cl::init(true));
 
 namespace {
   /// TBAANode - This is a simple wrapper around an MDNode which provides a
@@ -137,7 +141,13 @@ namespace {
   private:
     virtual void getAnalysisUsage(AnalysisUsage &AU) const;
     virtual AliasResult alias(const Location &LocA, const Location &LocB);
-    virtual bool pointsToConstantMemory(const Location &Loc);
+    virtual bool pointsToConstantMemory(const Location &Loc, bool OrLocal);
+    virtual ModRefBehavior getModRefBehavior(ImmutableCallSite CS);
+    virtual ModRefBehavior getModRefBehavior(const Function *F);
+    virtual ModRefResult getModRefInfo(ImmutableCallSite CS,
+                                       const Location &Loc);
+    virtual ModRefResult getModRefInfo(ImmutableCallSite CS1,
+                                       ImmutableCallSite CS2);
   };
 }  // End of anonymous namespace
 
@@ -220,17 +230,71 @@ TypeBasedAliasAnalysis::alias(const Location &LocA,
   return NoAlias;
 }
 
-bool TypeBasedAliasAnalysis::pointsToConstantMemory(const Location &Loc) {
+bool TypeBasedAliasAnalysis::pointsToConstantMemory(const Location &Loc,
+                                                    bool OrLocal) {
   if (!EnableTBAA)
-    return AliasAnalysis::pointsToConstantMemory(Loc);
+    return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
 
   const MDNode *M = Loc.TBAATag;
-  if (!M) return false;
+  if (!M) return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
 
   // If this is an "immutable" type, we can assume the pointer is pointing
   // to constant memory.
   if (TBAANode(M).TypeIsImmutable())
     return true;
 
-  return AliasAnalysis::pointsToConstantMemory(Loc);
+  return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
+}
+
+AliasAnalysis::ModRefBehavior
+TypeBasedAliasAnalysis::getModRefBehavior(ImmutableCallSite CS) {
+  if (!EnableTBAA)
+    return AliasAnalysis::getModRefBehavior(CS);
+
+  ModRefBehavior Min = UnknownModRefBehavior;
+
+  // If this is an "immutable" type, we can assume the call doesn't write
+  // to memory.
+  if (const MDNode *M = CS.getInstruction()->getMetadata(LLVMContext::MD_tbaa))
+    if (TBAANode(M).TypeIsImmutable())
+      Min = OnlyReadsMemory;
+
+  return ModRefBehavior(AliasAnalysis::getModRefBehavior(CS) & Min);
+}
+
+AliasAnalysis::ModRefBehavior
+TypeBasedAliasAnalysis::getModRefBehavior(const Function *F) {
+  // Functions don't have metadata. Just chain to the next implementation.
+  return AliasAnalysis::getModRefBehavior(F);
+}
+
+AliasAnalysis::ModRefResult
+TypeBasedAliasAnalysis::getModRefInfo(ImmutableCallSite CS,
+                                      const Location &Loc) {
+  if (!EnableTBAA)
+    return AliasAnalysis::getModRefInfo(CS, Loc);
+
+  if (const MDNode *L = Loc.TBAATag)
+    if (const MDNode *M =
+          CS.getInstruction()->getMetadata(LLVMContext::MD_tbaa))
+      if (!Aliases(L, M))
+        return NoModRef;
+
+  return AliasAnalysis::getModRefInfo(CS, Loc);
+}
+
+AliasAnalysis::ModRefResult
+TypeBasedAliasAnalysis::getModRefInfo(ImmutableCallSite CS1,
+                                      ImmutableCallSite CS2) {
+  if (!EnableTBAA)
+    return AliasAnalysis::getModRefInfo(CS1, CS2);
+
+  if (const MDNode *M1 =
+        CS1.getInstruction()->getMetadata(LLVMContext::MD_tbaa))
+    if (const MDNode *M2 =
+          CS2.getInstruction()->getMetadata(LLVMContext::MD_tbaa))
+      if (!Aliases(M1, M2))
+        return NoModRef;
+
+  return AliasAnalysis::getModRefInfo(CS1, CS2);
 }