X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FAnalysis%2FAliasAnalysis.h;h=ef31e1fdc45a4b90a1c5409cc61a12b0a31beafb;hb=5cb66e24d42b40d087989199297c369b3f3b2766;hp=fb848ebd570c8a9a672097a378ce364a3e2ca473;hpb=dd298c8c6eb036baf35bf5a559c59d2afd2c7944;p=oota-llvm.git

diff --git a/include/llvm/Analysis/AliasAnalysis.h b/include/llvm/Analysis/AliasAnalysis.h
index fb848ebd570..ef31e1fdc45 100644
--- a/include/llvm/Analysis/AliasAnalysis.h
+++ b/include/llvm/Analysis/AliasAnalysis.h
@@ -100,6 +100,29 @@ public:
   ///
   virtual bool pointsToConstantMemory(const Value *P) { return false; }
 
+  /// doesNotAccessMemory - If the specified function is known to never read or
+  /// write memory, return true.  If the function only reads from known-constant
+  /// memory, it is also legal to return true.
+  ///
+  /// Many optimizations (such as CSE and LICM) can be performed on calls to it,
+  /// without worrying about aliasing properties, and many functions have this
+  /// property (e.g. 'sin' and 'cos').
+  ///
+  /// This property corresponds to the GCC 'const' attribute.
+  ///
+  virtual bool doesNotAccessMemory(Function *F) { return false; }
+
+  /// onlyReadsMemory - If the specified function is known to only read from
+  /// non-volatile memory (or not access memory at all), return true.
+  ///
+  /// This property allows many common optimizations to be performed in the
+  /// absence of interfering store instructions, such as CSE of strlen calls.
+  ///
+  /// This property corresponds to the GCC 'pure' attribute.
+  ///
+  virtual bool onlyReadsMemory(Function *F) { return doesNotAccessMemory(F); }
+
+
   //===--------------------------------------------------------------------===//
   /// Simple mod/ref information...
   ///
@@ -117,11 +140,7 @@ public:
   /// a particular call site modifies or reads the memory specified by the
   /// pointer.
   ///
-  virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size) {
-    // If P points to a constant memory location, the call definitely could not
-    // modify the memory location.
-    return pointsToConstantMemory(P) ? Ref : ModRef;
-  }
+  virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
 
   /// getModRefInfo - Return information about whether two call sites may refer
   /// to the same set of memory locations.  This function returns NoModRef if
@@ -129,17 +148,15 @@ public:
   /// some of the same memory, Mod if they both write to some of the same
   /// memory, and ModRef if they read and write to the same memory.
   ///
-  virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
-    return ModRef;
-  }
+  virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2);
 
   /// Convenience functions...
   ModRefResult getModRefInfo(LoadInst *L, Value *P, unsigned Size);
-  ModRefResult getModRefInfo(StoreInst*S, Value *P, unsigned Size);
-  ModRefResult getModRefInfo(CallInst  *C, Value *P, unsigned Size) {
+  ModRefResult getModRefInfo(StoreInst *S, Value *P, unsigned Size);
+  ModRefResult getModRefInfo(CallInst *C, Value *P, unsigned Size) {
     return getModRefInfo(CallSite(C), P, Size);
   }
-  ModRefResult getModRefInfo(InvokeInst*I, Value *P, unsigned Size) {
+  ModRefResult getModRefInfo(InvokeInst *I, Value *P, unsigned Size) {
     return getModRefInfo(CallSite(I), P, Size);
   }
   ModRefResult getModRefInfo(Instruction *I, Value *P, unsigned Size) {