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.

Also modified some code to not access the GlobalAddress map directly.

llvm-svn: 10674

1 files changed, 21 insertions, 5 deletions

diff --git a/llvm/lib/ExecutionEngine/ExecutionEngine.cpp b/llvm/lib/ExecutionEngine/ExecutionEngine.cpp
index 45643abca9d..76ba2284306 100644
--- a/llvm/lib/ExecutionEngine/ExecutionEngine.cpp
+++ b/llvm/lib/ExecutionEngine/ExecutionEngine.cpp
@@ -47,6 +47,21 @@ ExecutionEngine::~ExecutionEngine() {
   delete MP;
 }
 
+/// getGlobalValueAtAddress - Return the LLVM global value object that starts
+/// at the specified address.
+///
+const GlobalValue *ExecutionEngine::getGlobalValueAtAddress(void *Addr) {
+  // If we haven't computed the reverse mapping yet, do so first.
+  if (GlobalAddressReverseMap.empty()) {
+    for (std::map<const GlobalValue*, void *>::iterator I = 
+           GlobalAddressMap.begin(), E = GlobalAddressMap.end(); I != E; ++I)
+      GlobalAddressReverseMap.insert(std::make_pair(I->second, I->first));
+  }
+
+  std::map<void *, const GlobalValue*>::iterator I =
+    GlobalAddressReverseMap.find(Addr);
+  return I != GlobalAddressReverseMap.end() ? I->second : 0;
+}
 
 // CreateArgv - Turn a vector of strings into a nice argv style array of
 // pointers to null terminated strings.
@@ -133,8 +148,8 @@ void *ExecutionEngine::getPointerToGlobal(const GlobalValue *GV) {
   if (Function *F = const_cast<Function*>(dyn_cast<Function>(GV)))
     return getPointerToFunction(F);
 
-  assert(GlobalAddress[GV] && "Global hasn't had an address allocated yet?");
-  return GlobalAddress[GV];
+  assert(GlobalAddressMap[GV] && "Global hasn't had an address allocated yet?");
+  return GlobalAddressMap[GV];
 }
 
 /// FIXME: document
@@ -435,12 +450,12 @@ void ExecutionEngine::emitGlobals() {
       addGlobalMapping(I, new char[Size]);
 
       DEBUG(std::cerr << "Global '" << I->getName() << "' -> "
-                      << (void*)GlobalAddress[I] << "\n");
+                      << getPointerToGlobal(I) << "\n");
     } else {
       // External variable reference. Try to use the dynamic loader to
       // get a pointer to it.
       if (void *SymAddr = GetAddressOfSymbol(I->getName().c_str()))
-        GlobalAddress[I] = SymAddr;
+        addGlobalMapping(I, SymAddr);
       else {
         std::cerr << "Could not resolve external global address: "
                   << I->getName() << "\n";
@@ -460,11 +475,12 @@ void ExecutionEngine::emitGlobals() {
 // address specified in GlobalAddresses, or allocates new memory if it's not
 // already in the map.
 void ExecutionEngine::EmitGlobalVariable(const GlobalVariable *GV) {
-  void *&GA = GlobalAddress[GV];
+  void *GA = getPointerToGlobalIfAvailable(GV);
   const Type *ElTy = GV->getType()->getElementType();
   if (GA == 0) {
     // If it's not already specified, allocate memory for the global.
     GA = new char[getTargetData().getTypeSize(ElTy)];
+    addGlobalMapping(GV, GA);
   }
 
   InitializeMemory(GV->getInitializer(), GA);