Add new ExecutionEngine::getGlobalValueAtAddress method, which can efficiently

turn a memory address back into the LLVM global object that starts at that
address.  Note that this won't cause any additional datastructures to be built
for clients of the EE that don't need this information.

llvm-svn: 10673

1 files changed, 25 insertions, 6 deletions

diff --git a/llvm/include/llvm/ExecutionEngine/ExecutionEngine.h b/llvm/include/llvm/ExecutionEngine/ExecutionEngine.h
index cf010084b70..2e4b3deda6a 100644
--- a/llvm/include/llvm/ExecutionEngine/ExecutionEngine.h
+++ b/llvm/include/llvm/ExecutionEngine/ExecutionEngine.h
@@ -36,9 +36,15 @@ class ExecutionEngine {
   Module &CurMod;
   const TargetData *TD;
 
-  // GlobalAddress - A mapping between LLVM global values and their actualized
-  // version...
-  std::map<const GlobalValue*, void *> GlobalAddress;
+  /// GlobalAddressMap - A mapping between LLVM global values and their
+  /// actualized version...
+  std::map<const GlobalValue*, void *> GlobalAddressMap;
+
+  /// GlobalAddressReverseMap - This is the reverse mapping of GlobalAddressMap,
+  /// used to convert raw addresses into the LLVM global value that is emitted
+  /// at the address.  This map is not computed unless getGlobalValueAtAddress
+  /// is called at some point.
+  std::map<void *, const GlobalValue*> GlobalAddressReverseMap;
 protected:
   ModuleProvider *MP;
 
@@ -74,17 +80,24 @@ public:
 
 
   void addGlobalMapping(const GlobalValue *GV, void *Addr) {
-    void *&CurVal = GlobalAddress[GV];
+    void *&CurVal = GlobalAddressMap[GV];
     assert((CurVal == 0 || Addr == 0) && "GlobalMapping already established!");
     CurVal = Addr;
+
+    // If we are using the reverse mapping, add it too
+    if (!GlobalAddressReverseMap.empty()) {
+      const GlobalValue *&V = GlobalAddressReverseMap[Addr];
+      assert((V == 0 || GV == 0) && "GlobalMapping already established!");
+      V = GV;
+    }
   }
 
   /// getPointerToGlobalIfAvailable - This returns the address of the specified
   /// global value if it is available, otherwise it returns null.
   ///
   void *getPointerToGlobalIfAvailable(const GlobalValue *GV) {
-    std::map<const GlobalValue*, void*>::iterator I = GlobalAddress.find(GV);
-    return I != GlobalAddress.end() ? I->second : 0;
+    std::map<const GlobalValue*, void*>::iterator I = GlobalAddressMap.find(GV);
+    return I != GlobalAddressMap.end() ? I->second : 0;
   }
 
   /// getPointerToGlobal - This returns the address of the specified global
@@ -107,6 +120,12 @@ public:
     return getPointerToFunction(F);
   }
 
+  /// getGlobalValueAtAddress - Return the LLVM global value object that starts
+  /// at the specified address.
+  ///
+  const GlobalValue *getGlobalValueAtAddress(void *Addr);
+
+
   void StoreValueToMemory(GenericValue Val, GenericValue *Ptr, const Type *Ty);
   void InitializeMemory(const Constant *Init, void *Addr);