stub out some LazyValueInfo interfaces, and have JumpThreading

start using them in a trivial way when -enable-jump-threading-lvi
is passed.  enable-jump-threading-lvi will be my playground for 
awhile.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86789 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 28 insertions, 7 deletions

diff --git a/include/llvm/Analysis/LazyValueInfo.h b/include/llvm/Analysis/LazyValueInfo.h
index 29f8180..0553e9e 100644
--- a/include/llvm/Analysis/LazyValueInfo.h
+++ b/include/llvm/Analysis/LazyValueInfo.h
@@ -18,23 +18,44 @@
 #include "llvm/Pass.h"
 
 namespace llvm {
-
+  class Constant;
+  class TargetData;
+  class Value;
+  
 /// LazyValueInfo - This pass computes, caches, and vends lazy value constraint
 /// information.
 class LazyValueInfo : public FunctionPass {
+  class TargetData *TD;
+  void *PImpl;
 public:
   static char ID;
-  LazyValueInfo();
+  LazyValueInfo() : FunctionPass(&ID), PImpl(0) {}
+
+  /// Tristate - This is used to return yes/no/dunno results.
+  enum Tristate {
+    Unknown = -1, No = 0, Yes = 1
+  };
+  
+  
+  // Public query interface.
+  
+  
+  /// isEqual - Determine whether the specified value is known to be equal or
+  /// not-equal to the specified constant at the end of the specified block.
+  Tristate isEqual(Value *V, Constant *C, BasicBlock *BB);
 
+  /// getConstant - Determine whether the specified value is known to be a
+  /// constant at the end of the specified block.  Return null if not.
+  Constant *getConstant(Value *V, BasicBlock *BB);
+  
+  
+  // Implementation boilerplate.
+  
   virtual void getAnalysisUsage(AnalysisUsage &AU) const {
     AU.setPreservesAll();
   }
   virtual void releaseMemory();
-  
-  virtual bool runOnFunction(Function &F) {
-    // Fully lazy.
-    return false;
-  }
+  virtual bool runOnFunction(Function &F);
 };
 
 }  // end namespace llvm